HomeMy WebLinkAboutPermit File BLD-2023-0162 2313 R Avenue (2) FIGURES
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MODEL RESULTS
*Bold row=surcharged pipe
Basin F3/F4 Modeled Stormwater Results
Ex. Pipe New Pipe Surcharge Capacity Modeled Percent
Pipe ID Upstream Node Diam (in.) Diam(in.) Depth(ft) (cfs) Flow(cfs) Full
1299P 1299 24 0.0 118.8 34.5 29%
1306P 1306 30 0.0 74.8 48.6 65%
1 22.1 33.2 150%
1427P 1427 10 0.0 3.1 2.2 71%
1445P 1445 12 0.0 6.5 0.7 11%
1447P 1447 15 0.0 38.4 0.7 2%
1450P 1450 15 0.0 2.9 0.4 13%
1451P 1451 12 0.0 6.0 0.4 6%
1452P 1452 12 0.0 6.9 0.4 5%
1453P 1453 12 0.0 8.9 0.7 7%
1480P 1480 12 0.0 3.4 2.2 63%
1556P 1556 8 0.0 3.5 1.0 28%
1566P 1566 12 1.6 13.9 2.3 16%
1591P 1591 15 0.0 17.2 10.1 58%
1597P 1597 24 0.0 130.0 10.1 8%
1603P 1603 24 0.0 44.1 13.9 32%
1628P 1628 12 0.0 8.5 3.8 45%
1645P 1645 12 0.0 26.9 1.0 4%
1646P 1646 12 0.0 2.5 -1.0 -38%
1710P 1710 8 0.0 2.7 0.5 19%
1778P 1778 12 1.9 5.7 3.4 60%
1819P 1819 15 0.0 2.9 -0.8 -28%
1820P 1820 8 1.1 2.3 2.3 99%
1827P 1827 8 0.0 3.1 2.3 73%
1828P 1828 8 0.0 3.0 2.3 76%
1986P 1986 18 0.0 19.1 7.9 41%
2006P 2006 10 0.0 3.6 3.0 82%
2009P 2009 12 0.0 8.9 3.0 34%
2021P 2021 18 0.0 26.2 5.2 20%
2436P 2436 8 0.0 3.1 2.2 69%
2571P 2571 36 0.0 105.5 1.5 1%
2573P 2573 12 0.0 4.6 1.5 33%
2665P 2665 15 0.0 13.9 0.8 6%
2760P 2760 12 0.0 5.1 3.3 65%
.0. 2790 0%
3020P 3020 30 0.0 98.7 48.6 49%
3102P 3102 18 0.7 20.6 7.9 38%
3103P 3103 18 0.0 16.3 7.9 48%
3105P 3105 18 0.0 21.9 7.9 36%
3110P 3110 12 0.0 7.5 3.2 43%
3111P 3111 12 0.0 7.3 3.2 44%
3116P 3116 12 0.0 8.6 1.7 20%
3117P 3117 12 0.0 2.1 1.7 79%
3118P 3118 12 0.0 8.6 1.7 20%
P. 1
*Bold row=surcharged pipe
Basin F3/F4 Modeled Stormwater Results
Ex. Pipe New Pipe Surcharge Capacity Modeled Percent
Pipe ID Upstream Node Diam (in.) Diam(in.) Depth(ft) (cfs) Flow(cfs) Full
3119P 3119 12 0.0 8.8 1.7 19%
3121P 3121 12 0.0 10.6 1.7 16%
3123P 3123 12 0.0 5.7 1.7 30%
3124P 3124 12 0.0 5.0 1.7 34%
3126P 3126 12 0.0 2.6 1.7 65%
3127P 3127 12 0.0 2.6 1.7 66%
3130P 3130 12 0.0 8.1 1.5 19%
3131P 3131 12 0.0 8.2 1.5 19%
3134P 3134 12 0.0 8.3 1.5 18%
3135P 3135 12 0.0 8.0 1.5 19%
3136P 3136 12 0.0 3.1 1.5 49%
3137P 3137 12 0.0 9.1 1.5 17%
3140P 3140 12 0.0 0.4 -0.8 -180%
3141P 3141 8 0.0 1.4 0.8 54%
3156P 3156 18 0.0 1.8 1.0 54%
18 0.0 1.0
3247P 3247 1 18 0.0 10.8 4.3 40%
3303P 3303 18 0.0 6.7 -4.3 -64%
3308P 3308 18 0.0 24.7 4.3 18%
358P 358 8 0.0 2.4 0.5 22%
4067P 4067 8 0.0 1.1 0.5 46%
4068P 4068 8 0.0 0.6 -0.5 -83%
4069P 4069 12 0.0 3.3 -0.5 -16%
4148P 4148 12 0.0 3.4 1.7 50%
486P 486 18 0.0 21.2 6.8 32%
518P 518 8 0.7 3.8 2.2 58%
519P 519 8 0.0 3.0 2.2 73%
520P 520 8 0.0 3.2 2.2 67%
0%
0 ' 2.1 2.2 106%
569P 569 12 0.0 5.6 0.7 12%
594P 594 12 0.0 4.3 0.7 15%
595P 595 12 0.0 3.9 0.7 17%
596P 596 12 0.0 3.0 0.7 22%
597P 597 15 0.0 6.4 0.7 10%
605P 605 12 0.0 11.8 0.8 6%
607P 607 8 0.0 1.2 0.8 61%
608P 608 10 0.0 5.7 1.6 28%
609P 609 10 0.0 2.5 1.6 63%
610P 610 10 0.0 1.6 1.6 96%
611P 611 10 0.0 1.8 1.6 86%
612P 612 12 0.0 3.1 1.6 51%
622P 622 21 0.0 17.6 5.5 31%
P. 2
*Bold row=surcharged pipe
Basin F3/F4 Modeled Stormwater Results
Ex. Pipe New Pipe Surcharge Capacity Modeled Percent
Pipe ID Upstream Node Diam (in.) Diam(in.) Depth(ft) (cfs) Flow(cfs) Full
624P 624 21 0.0 30.1 5.5 18%
640P 640 12 0.0 5.8 3.8 66%
641P 641 12 0.0 3.3 3.8 116%
651P 851 18 0.0 14.0 7.9 56%
792P 792 18 0.0 42.8 4.3 10%
793P 793 12 0.0 7.7 4.3 56%
794P 794 12 0.0 5.2 4.3 83%
961P 961 15 0.0 12.7 0.7 6%
F03-1001P F03-1001 21 0.0 59.2 0.5 1%
1 112P F03-1002 21 30 1
F03-1003P F03-1003 21 0.0 11.2 5.4 49%
F03-1004P F03-1004 21 0.0 28.0 15.0 54%
F03-1005P F03-1005 21 0.0 34.1 15.8 46%
F03-1006P F03-1006 36 0.0 51.2 25.6 50%
F03-1007P F03-1007 21 0.0 25.5 4.5 18%
F03-1008P F03-1008 10 0.0 4.1 2.2 53%
F03-1009P F03-1009 10 0.0 4.5 2.2 48%
F03-1010P F03-1010 12 0.0 10.6 2.2 20%
F03-1011P F03-1011 15 0.0 8.3 3.9 47%
F03-1012P F03-1012 12 0.0 6.6 1.8 27%
F03-1013P F03-1013 8 1.3 1.9 1.8 96%
F03-1014P F03-1014 18 2.7 2.7 -9.6 -353%
F03-1015P F03-1015 10 0.0 3.7 3.0 81%
F03-1016P F03-1016 21 0.0 29.9 18.8 63%
F03-1018P F03-1018 18 0.0 11.0 7.3 66%
F03-1019P F03-1019 18 0.0 10.3 5.2 50%
1 1 1• 1 1 / 8 18 2.6 1 1 4%
F03-1022P F03-1022 15 0.0 9.4 6.8 73%
F03-1023P F03-1023 15 0.0 8.7 6.8 78%
F03-1024P F03-1024 15 0.0 9.8 6.8 70%
F03-1025P F03-1025 18 0.0 16.8 6.8 41%
F03-1026P F03-1026 18 1.6 4.8 -6.8 -143%
f03-1027P f03-1027 27 0.0 34.7 33.4 96%
F03-1028P F03-1028 27 0.0 31.6 33.4 106%
F03-1029P F03-1029 27 0.0 40.0 33.4 84%
F03-1030P F03-1030 27 0.0 32.9 34.4 105%
F03-1031P F03-1031 30 0.0 48.7 34.4 71%
F03-1032P F03-1032 18 0.0 11.5 1.0 9%
F03-1033P F03-1033 18 0.0 9.0 2.2 24%
1 1 4 • 1 1
F03-1036P F03-1036 18 0.0 12.6 3.8 30%
F03-1037P F03-1037 36 0.0 84.1 -5.2 -6%
1 138P F03-1038 10 18 44 1 : 3.0
F03-1039P F03-1039 30 0.0 53.5 2.3 47
77
P.3
*Bold row=surcharged pipe
Basin F3/F4 Modeled Stormwater Results
Ex. Pipe New Pipe Surcharge Capacity Modeled Percent
Pipe ID Upstream Node Diam (in.) Diam (in.) Depth(ft) (cfs) Flow(cfs) Full
F03-1040P F03-1040 15 0.0 4.8 1.5 31%
F03-1041P F03-1041 30 0.0 22.3 -4.5 -20%
F03-1042P F03-1042 12 0.0 16.9 1.6 9%
F03-1043P F03-1043 30 0.0 75.6 1 -2.9 -4%
F03-1044P F03-1044 30 0.0 90.8 2.9 3%
F03-1045P F03-1045 18 0.0 10.5 9.6 91%
F03-1046P F03-1046 30 0.0 148.8 4.5 3%
F03-1047P F03-1047 18 0.0 16.9 7.3 43%
F03-1048P F03-1048 15 0.0 15.1 1.1 7%
F03-1051P F03-1051 24 0.0 14.4 3.7 26%
F03-1052P F03-1052 36 0.0 120.0 26.2 22%
F03-1054P F03-1054 15 0.0 12.8 0.4 3%
F03-1055P F03-1055 24 0.0 60.3 1.4 2%
F03-1056P F03-1056 8 0.0 1.8 1.4 77%
F03-1057P F03-1057 21 0.0 32.3 26.7 83%
F03-1065P F03-1065 15 3.9 9.6 9.6 100%
1 1. 1 06 1
F03-1067P F03-1067 15 0.0 22.3 9.6 43%
/ 1.•• 1 1.• 80%
F03-1070P F03-1070 14 1 2.0 15.0 9.6 64%
F03-1072P F03-1072 12 0.0 6.0 3.2 53%
/ 173P F03-1073 12 18 1 1 3.2 160%
F03-1074P F03-1074 12 1.4 1.0 -3.2 -320%
F03-1075P F03-1075 18 0.0 7.6 1.7 22%
F03-1076P F03-1076 18 0.0 18.3 7.9 43%
F03-1078P F03-1078 24 0.0 14.9 2.0 13%
F03-1079P F03-1079 36 0.0 77.7 35.9 46%
F03-1080P F03-1080 30 0.6 81.0 -34.4 -43%
F03-1081P F03-1081 24 0.0 24.9 2.0 8%
F03-1082P F03-1082 18 0.0 10.8 2.0 19%
F03-1083P F03-1083 18 0.0 11.9 2.0 17%
F03-1084P F03-1084 36 0.0 130.7 37.0 28%
F03-1087P F03-1087 15 0.0 2.9 0.7 26%
F03-1094P F03-1094 21 0.0 37.9 18.8 50%
F03-1095P F03-1095 18 0.0 17.5 3.8 21%
F03-1096P F03-1096 12 0.0 7.6 1.6 21%
1 1• 1 1•
F03-1099P F03-1099 36 0.0 82.5 26.2 32%'
F03-1341P F03-1341 24 0.0 7.3 -5.2 -70%
F03-1342P F03-1342 36 0.0 63.5 5.2 8%
F04-1001P F04-1001 24 0.0 60.7 19.2 32%
F04-1002P F04-1002 24 0.0 18.5 19.2 103%
F04-1003P F04-1003 24 0.0 42.0 19.2 46%
P.4
*Bold row=surcharged pipe
Basin F3/F4 Modeled Stormwater Results �
EX. Pipe New Pipe Surcharge Capacity Modeled Percent
Pipe ID Upstream Node Diam(in.) Diam(in.) Depth(ft) (cfs) Flow(cfs) Full
F04-1004P F04-1004 24 0.0 46.0 19.2 42%
F04-1006P F04-1006 24 0.0 38.7 19.2 50%
F04-1007P F04-1007 24 0.0 44.8 19.2 43%
F04-1008P F04-1008 24 0.0 52.8 19.2 36%
F04-1009P F04-1009 12 0.0 5.9 2.2 37%
F04-1010P F04-1010 18 0.0 6.6 4.3 66%
F04-1011P F04-1011 18 0.0 8.1 4.3 53%
F04-1012P F04-1012 18 0.0 20.6 4.3 21%
F04-1013P F04-1013 18 0.0 4.2 4.3 104°%
F04-1014P F04-1014 18 0.0 17.1 4.3 25%
F04-1016P F04-1016 18 0.0 15.8 4.3 27°%
F04-1017P F04-1017 18 0.0 14.0 4.3 31%
F04-1018P F04-1018 30 0.0 98.1 48.6 50%
F04-1020P F04-1020 24 0.0 55.7 15.6 28%
F04-1021P F04-1021 24 0.0 48.1 15.6 32%
F04-1022P F04-1022 24 0.0 29.2 14.3 49%
F04-1023P F04-1023 24 0.0 30.0 14.3 48%
F04-1024P F04-1024 24 0.0 28.3 14.3 51%
F04-1025P F04-1025 24 0.0 26.7 14.3 54%
F04-1026P F04-1026 24 0.0 38.6 14.3 37%
F04-1027P F04-1027 18 0.0 15.4 14.3 93%
F04-1028P F04-1028 18 0.0 18.0 14.3 79%
F04-1057P F04-1057 15 1.8 10.5 10.1 96%
F04-1058P F04-1058 24 0.0 38.3 10.1 26%
F04-1059P F04-1059 15 0.0 10.3 10.1 98%
F04-1062P F04-1062 48 0.0 113.3 98.3 87%
F04-1063P F04-1063 42 0.0 151.9 88.8 58%
F04-1064P F04-1064 42 0.0 133.1 88.8 67%
F04-1065P F04-1065 42 0.0 133.1 85.6 64%
F04-1066P F04-1066 24 0.0 30.5 3.5 11%
F04-1068P F04-1069 24 0.0 36.6 7.6 21%
F04-1069P F04-1069 24 0.0 41.1 7.6 18%
F04-1070P F04-1070 24 0.0 20.0 3.3 17%
F04-1071P F04-1071 24 0.0 27.3 4.2 15%
F04-1072P F04-1072 18 0.0 11.3 4.2 38%
F04-1073P F04-1073 12 0.0 4.5 4.2 93%
F04-1074P F04-1074 36 0.0 119.0 83.0 70%
F04-1075P F04-1075 27 6.7 34.4 33.2 96%
1 1 1 . 27 30
F04-1078P F04-1078 18 0.0 15.6 3.3 21%
F04-1079P F04-1079 12 0.0 3.9 3.3 85%
F04-1081P F04-1081 24 0.0 34.2 10.1 29%
F04-1082P F04-1082 24 0.0 36.6 13.9 38%
1 0 1 1
P.5
*Bold row=surcharged pipe
Basin F3/F4 Modeled Stormwater Results
Ex. Pipe New Pipe Surcharge Capacity Modeled Percent
Pipe ID Upstream Node Diam (in.) Diam (in.) Depth(ft) (cfs) Flow(cfs) Full
F04-1084P F04-1084 30 0.0 101.1 48.6 48%
F04-1085P F04-1085 30 0.0 94.5 48.6 51%
F04-1086P F04-1086 30 0.0 76.5 52.0 68%
F04-1087P F04-1087 36 0.0 113.6 52.0 46%
F04-1088P F04-1088 30 0.0 78.7 52.0 66%
F04-1089P F04-1089 36 0.0 131.9 52.0 39%
F04-1090P F04-1090 36 0.0 138.8 52.0 37%
F04-1107P F04-1107 15 0.0 11.3 3.5 31%
F04-1108P F04-1108 12 0.0 4.0 2.2 55%
F04-1110P F04-1110 24 0.0 38.8 3.3 9%
F04-1114P F04-1114 12 0.0 4.7 3.3 72%
F04-1116P F04-1116 24 0.0 46.0 7.6 16%
F04-1117P F04-1117 48 0.0 113.1 98.3 87%
F04-1122P F04-1122 36 0.0 116.7 83.0 71%
F04-1126P F04-1126 24 0.0 82.3 15.6 19%
F04-1127P F04-1127 24 0.0 57.7 19.2 33%
F04-1128P F04-1128 24 0.0 41.1 15.6 38%
F04-1129P F04-1129 30 0.0 76.9 48.6 63%
F04-1134P F04-1134 15 0.0 13.2 10.1 76%
F04-1143P F04-1143 15 0.0 7.1 1.3 19%
F04-1144P F04-1144 12 0.0 4.3 1.3 31%
F04-1145P F04-1145 18 0.0 7.1 1.3 19%
F04-1146P F04-1146 24 0.1 11.7 4.5 38%
F04-1147P F04-1147 24 1.2 7.2 -4.6 -63%
F04-1148P F04-1148 12 0.0 3.9 2.0 52%
F04-1151P F04-1151 12 0.0 9.4
F04-1156P F04-1156 15 0.0 9.2 5.0 54%
F04-1157P F04-1157 15 0.0 14.6 4.5 31%
F04-1158P F04-1158 12 0.8 4.6 3.8 84%
F04-1167P F04-1167 18 0.0 16.8 3.5 21%
F04-1591P F04-1591 42 0.0 96.5 88.8 92%
11 1
Link282 Dt 12 13.0 1 16.7 3.2 1 19%
Node18P Node18 24 0.0 43.0 19.2 45%
P. 6
I
TAB 5 (MINIMUM REQUIREMENT#5)
• 1-3.4.5 Minimum Requirement#5—On-site Stormwater Management
Projects shall employ Stormwater Management BMPs in accordance with the following thresholds,
standards, and lists to infiltrate, disperse, and retain stormwater runoff on site to the extent feasible
without causing flooding or erosion impacts.
Project thresholds that trigger Minimum Requirements#1 through#5, shall utilize the On-site
Stormwater Management BMP's from List#1 for all surfaces within each type of surface in List#1; or,
Demonstrate compliance with the LID Performance Standard. Projects selecting this option cannot use
Rain Gardens. They may choose to use Bioretention BMP's as described in Chapter V-7—Infiltration
and Bioretention Treatment Facilities to achieve the LID Performance Standard.
Refer to this section of the reference Manual for all Feasibility or Infeasibility Criteria for List#1
and List#2.
Is this project Flow Control Exempt? YES (Yes\No) (See Appendix I-E:Flow Control-Exempt
Surface Water). If yes, provide reasoning from the applicability section of 1-2.5.7 Minimum
Requirement#7: Flow Control). If No, then the project triggers Minimum Requirement#7 (1-2.5.7) and
possibly Minimum Requirement#8 (1-2.5.8).
Site stormwater is collected and conveyed to Fidalgo Bay, a saltwater body and designated as flow
control exempt. Post Construction Soils Quality and Depth (BMP T5.13)will be applied. There are no
roofs or roofdrains in the proposed development.
If the project is Flow Control Exempt, select from the List 3 below: (Skip List 1 and List 2)
o BMP T5.13 Post Construction Soils Quality and Depth
o BMP T5.10A: Downspout Full Infiltration, or;
o BMP T5.10B Downspout Dispersion Systems, or;
o BMP T5.1 OC: Performated Stub-out Connections, or;
LID Performance Standard
The LID Performance Standard compliance method for Minimum Requirement#5 requires modeling the
proposed Flow Control BMPs to demonstrate the flow reduction as described below. Note that in order
to meet the LID Performance Standard, the chosen Flow Control BMPs will most likely need to include
infiltration.
Stormwater discharges shall match developed discharge durations to pre-developed durations for the
range of pre-developed discharge rates from 8% of the 2-year peak flow to 50% of the 2-year peak flow.
Refer to the Flow Control Performance Standard section in 1-3.4.7 MR7: Flow Control for information
about the assignment of the pre-developed condition. Project sites that must also meet 1-3.4.7 MR7:
Flow Control must match flow durations between 8% of the 2-year flow through the full 50-year flow.
Designers selecting this option cannot use BMP T5.14: Rain Gardens to achieve the LID Performance
Standard. They may choose to use BMP T7.30: Bioretention to achieve the LID Performance Standard.
Version Date: August 30, 2022
TAB 6 — (MINUMUM REQUIREMENT 6 - RUNOFF TREATMENT)
See attached Stormwater Site Plan
Version Date: August 30, 2022
TAB 9 —(MINUMUM REQUIREMENT 9 —OPERATION AND MAINTENANCE)
Refer to 1.2.5.9 and provide the required information for this Minimum Requirement.
Version Date: August 30, 2022
Operations &
Maintenance
Ben Root Skate Park
Anacortes, WA
November 18, 2022
PREPARED FOR:
City of Anacortes
Contact: Jonn Lunsford
Phone: (360) 299-1953
CLIENT:
G � P C Grindline Skateparks, Inc.
Of WASI" F� 4619 14th Ave SW
Seattle, WA 98106
MacKay Sposito Prepared by:
43952
RFGISTF?, Project Number: 17811 Eric Pilcher, PE
s/ONAL
Ig/2�ZZ
Federal Way Office
MacKay+ SPoSlto 33810 Weyerhaeuser Way South,Suite 130• Federal Way,WA 98001
253.205.8700 • info@mackaysposito.com
Ben Root Skate Park
MacKay+sposito 0&M Plan
November 18,2022
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I
2 Page
Ben Root Skate Park
MacKay+sposito O&M Plan
November 18,2022
Table of Contents
1.0 Site Overview..................... ......... ... ........ ......... .............5
2.0 Pollutant Source Control.................:................................................................................................7
1
3.0 Water Quality BMPS........................................................................................................................7
4.0 References.......................................................................................................................................8
List of Figures
Figure 1. Site Plan........ . ...........6
List of Attachments
Attachment A: Pollutant Source-Specific BMPs
Attachment B: Water Quality BMP Maintenance Program
3iPage
I
Ben Root Skate Park
MacKay+Sposito 0&M Plan
November 18, 2022
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4 Page
Ben Root Skate Park
MacKay+Sposito 0&M Plan
November 18,2022
r SITE OVERVIEW
A new skate park and pump track facility,with associated parking lot, are planned on a 1.1-acre parcel
(P77984) located at 2313 R Avenue,Anacortes,WA 98221. Project improvements include a new asphalt
parking area with curb,gutter, and drainage structures, a concrete pedestrian path, 10,184 square foot
concrete skate park and a 3,548 square foot pump track.
Downstream conveyance from the site discharges directly to Fidalgo Bay.As a result,flow control at the
facility is not required. However,water quality pre-treatment is necessary from pollution generating
areas.Therefore,a filter strip has been sized at the eastern end of the parking lot to provide pollutant
removal from stormwater prior to discharge.
III
5 Page
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Ben Root Skate Park
MacKay Sposito 0&M Plan
November 18,2022
2.0 POLLUTANT SOURCE CONTROL
Volume IV of the 2019 Stormwater Management Manual for Western Washington (SWMMWW;Ecology
2019)provides guidance for pollutant source-specific best management practices (BMPs). Based on the
proposed land use for the Ben Root Skate Park the following site-specific BMPs may apply.
• S417 Maintenance of Stormwater Drainage and Treatment Facilities
• 5421 Parking and Storage for Vehicles and Equipment
• S411 Landscaping and Lawn/Vegetation Management
• S435 Pesticides and an Integrated Pest Management Program
• S450 Irrigation
• S436 Color Events
• S442 Labeling Storm Drain Inlets on Your Property
• S443 Fertilizer Application
Excerpts from the SWMMWW covering these BMPs are provided in Attachment A.
/ QUALITY BKPS
A filter strip will provide water quality treatment for runoff from pollution generating surfaces(i.e.,the
parking lot). Volume V-A of the SWMMWW provides guidance for a variety of stormwater BMPs.
Specific BMPs that are relevant to this project area:
A.10 Filter Strips
Maintenance standards from the SWMMWW covering these BMPs are provided in Attachment B.
7 �
Ben Root Skate Park
MacKay— `,posd O&M Plan
November 18,2022
Ecology 2019. Stormwater Management Manual for Western Washington, Publication Number 19-10-
21. Washington State Department of Ecology,Water Quality Program, Lacey,WA.July.
8 1 P a g e
Ben Root Skate Park
MacKay sposito O&M Plan
November 18,2022
Attachment A: Pollutant Source-Specific BMPs
S417 BMPs for Maintenance of Stormwater
Drainage and Treatment Systems
Description of Pollutant Sources: Facilities include roadside catch basins on arterials and within
residential areas,conveyance systems, detention facilities such as ponds and vaults,oil/water sep-
arators, biofilters,settling basins, infiltration systems,and all other types of stormwater treatment sys-
tems presented in Volume V. Oil and grease, hydrocarbons,debris, heavy metals, sediments and
contaminated water are found in catch basins, oil and water separators, settling basins, etc.
Pollutant Control Approach: Provide maintenance and cleaning of debris, sediments, and other
pollutants from stormwater collection,conveyance, and treatment systems to maintain proper oper-
ation.
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Applicable Operational BMPs:
Maintain stormwater treatment facilities per the operations and maintenance(O&M) procedures
presented in Appendix V-A: BMP Maintenance Tables in addition to the following BMPs:
. Inspect and clean treatment BMPs,conveyance systems,and catch basins as needed, and
determine necessary O&M improvements.
• Promptly repair any deterioration threatening the structural integrity of stormwater facilities.
These include replacement of clean-out gates,catch basin lids,and rock in emergency spill-
ways.
. Ensure adequacy of storm sewer capacities and prevent heavy sediment discharges to the
sewer system.
• Regularly remove debris and sludge from BMPs used for peak-rate control,treatment,etc.
and discharge to a sanitary sewer if approved by the sewer authority,or truck to an appro-
priate local or state government approved disposal site.
• Clean catch basins when the depth of deposits reaches 60 percent of the sump depth as
measured from the bottom of basin to the invert of the lowest pipe into or out of the basin.
However, in no case should there be less than six inches clearance from the debris surface to
the invert of the lowest pipe.Some catch basins(for example,WSDOT's Catch Basin Type IL
(WSDOT,2011))may have as little as 12 inches sediment storage below the invert.These
catch basins need frequent inspection and cleaning to prevent scouring.Where these catch
basins are part of a stormwater collection and treatment system,the system owner/operator
may choose to concentrate maintenance efforts on downstream control devices as part of a
systems approach.
. Properly dispose of all solids, polluted material,and stagnant water collected through system
cleaning. Do not decant water back into the drainage system from eductor trucks or vacuum
equipment since there may be residual contaminants in the cleaning equipment. Do notjet
material downstream into the public drainage system.
• Clean woody debris in a catch basin as frequently as needed to ensure proper operation of
the catch basin.
• Post warning signs;"Dump No Waste-Drains to Ground Water,""Streams,""Lakes,"or
emboss on or adjacent to all storm drain inlets where possible.
• Disposal of sediments and liquids from the catch basins must comply with Appendix IV-B:
Management of Street Waste Solids and Liquids.
S421 BMPs for Parking and Storage of Vehicles
and Equipment
Description of Pollutant Sources: Public and commercial parking lots such as retail store,fleet
vehicle(including rent-a-car lots and car dealerships),equipment sale and rental parking lots, and
2019 Stormwa ter Management Manual for Western Washington
Volume IV-Chapter 3-Page 517
parking lot driveways,can be sources of toxic hydrocarbons and other organic compounds,including
oils and greases,metals,and suspended solids.
Pollutant Control Approach: If the parking lot meets the site use thresholdsto determine if the
site is expected to generate high concentrations of oil, as defined in Step 2: Determine if an Oil Con-
trol BMP is Required in III-1.2 Choosing Your Runoff Treatment BMPs, provide oil removal equip-
ment forthe contaminated stormwater runoff.
Applicable Operational BMPs:
• If a parking lot must be washed,discharge the washwaterto a sanitary sewer, if allowed by
the local sewer authority,or other approved wastewater treatment system,or collect wash-
water for off-site disposal.
• Do not hose down the area to a storm sewer or receiving water.Vacuum sweep parking lots,
storage areas,and driveways regularly to collect dirt,waste,and debris. Mechanical or hand
sweeping may be necessary for areas where a vacuum sweeper cannot reach.
• Clean up vehicle and equipment fluid drips and spills immediately.
• Place drip pans below leaking vehicles(including inoperative vehicles and equipment)in a
mannerthat catches leaks or spills, including employee vehicles. Drip pans must be managed
to prevent overfilling and the contents disposed of properly.
Recommended Operational BMPs:
• Encourage employees to repair leaking personal vehicles.
. Encourage employees to carpool or use public transit through incentives.
. Encourage customers to use public transit by rewarding valid transit pass holders with dis-
counts.
. Install catch basin inserts to collect excess sediment and oil if necessary. Inspect and maintain
catch basin inserts to ensure they are working correctly.
Applicable Treatment BMPs:
Establishments subject to high-use intensity are significant sources of oil contamination of storm-
water. Examples of potential high use areas include customer parking lots at fast food stores,gro-
cery stores,taverns, restaurants,large shopping malls,discount warehouse stores,quick-lube
shops,and banks.
Refer to Step 2:Determine if an Oil Control BMP is Required in III-1.2 Choosing Your Runoff Treat-
ment BMPsfor the site use thresholdsthat determine if an oil control BMP is required,and for a list of
oil control BMPs.
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i
�I
S411 BMPs for Landscaping and Lawn / Vegetation
Management
Description of Pollutant Sources: Landscaping can include grading, soil transfer,vegetation
planting, and vegetation removal. Examples include weed control on golf course lawns,access
roads, and utility corridors and during landscaping;and residential lawn/plant care. Proper man-
agement of vegetation can minimize excess nutrients and pesticides.
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Pollutant Control Approach: Maintain appropriate vegetation to control erosion and the dis-
charge of stormwater pollutants.Prevent debris contamination of stormwater.Where practicable,
grow plant species appropriate forthe site, or adjustthe soil properties of the site to grow desired
plantspecies.
Applicable BMPs:
. Install engineered soil/landscape systems to improve the infiltration and regulation of storm-
water in landscaped areas.
. Select the right plants for the planting location based on proposed use, available main-
tenance,soil conditions,sun exposure,water availability, height,sight factors, and space avail-
able.
. Ensure that plants selected for planting are not on the noxious weed list. For example,but-
terfly bush often gets planted as an ornamental but is actually on the noxious weed list.
The Washington State Noxious Weed List can be found at the following webpage:
hftps://www.nwcb.wa.gov/printable-noxious-weed-list
. Do not dispose of collected vegetation into waterways or storm sewer systems.
• Do not blow vegetation or other debris into the drainage system.
. Dispose of collected vegetation such as grass clippings, leaves,sticks by composting or recyc-
ling.
. Remove, bag, and dispose of class A&B noxious weeds in the garbage immediately.
. Do not compost noxious weeds as it may lead to spreading through seed or fragment if the
composting process is not hot enough.
. Use manual and/or mechanical methods of vegetation removal(pincer-type weeding tools,
flame weeders,or hot water weeders as appropriate)ratherthan applying herbicides,where
practical.
. Use at least an eight-inch"topsoil'layer with at least 8 percent organic matter to provide a suf-
ficient vegetation-growing medium.
Organic matter is the least water-soluble form of nutrients that can be added to the soil.
Composted organic matter generally releases only between 2 and 10 percent of its total
nitrogen annually,and this release corresponds closely to the plant growth cycle.
Return natural plant debris and mulch to the soil,to continue recycling nutrients indef-
initely.
. Select the appropriate turfgrass mixture for the climate and soil type.
o Certain tall fescues and rye grasses resist insect attack because the symbiotic endo-
phytic fungi found naturally in their tissues repel or kill common leaf and stem-eating
lawn insects.
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■ The fungus causes no known adverse effects to the host plant or to humans.
■ Tall fescues and rye grasses do not repel root-feeding lawn pests such as Crane
Fly larvae.
■ Tall fescues and rye grasses are toxic to ruminants such as cattle and sheep
• Endophytic grasses are commercially available;use them in areas such as parks or golf
courses where grazing does not occur.
• Local agricultural or gardening resources such as Washington State University Exten-
sion office can offer advice on which types of grass are best suited to the area and soil
type.
• Use the following seeding and planting BMPs,or equivalent BMPs,to obtain information on
grass mixtures,temporary and permanent seeding procedures, maintenance of a recently
planted area,and fertilizer application rates: BMP C120:Temporary and Permanent Seeding,
BMP C121:Mulching, BMP C123:Plastic Covering,and BMP C124:Sodding.
. Adjusting the soil properties of the subject site can assist in selection of desired plant species.
Consult a soil restoration specialist for site-specific conditions.
Recommended Additional BMPs:
. Conduct mulch-mowing whenever practicable.
• Use native plants in landscaping. Native plants do not require extensive fertilizer or pesticide
applications. Native plants may also require less watering.
• Use mulch or other erosion control measures on soils exposed for more than one week during
the dry season(May 1 to September 30)or two days during the rainy season (October 1 to
April 30).
. Till a topsoil mix or composted organic material into the soil to create a well-mixed transition
layer that encourages deeper root systems and drought-resistant plants.
. Apply an annual topdressing application of 3/8"compost.Amending existing landscapes and
turf systems by increasing the percent organic matter and depth of topsoil can:
Substantially improve the permeability of the soil.
o Increase the disease and drought resistance of the vegetation.
o Reduces the demand for fertilizers and pesticides.
• Disinfect gardening tools after pruning diseased plants to prevent the spread of disease.
. Prune trees and shrubs in a manner appropriate for each species.
. If specific plants have a high mortality rate, assess the cause and replace with another more
appropriate species.
• When working around and below mature trees,follow the most current American National
Standards Institute(ANSI)ANSI A300 standards(see
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http://www.tcia.orgrrCIA/BUSINESS/ANSI_A300_Standards_rrCIA/BUSIN ESS/A300_
Standards/A300_Standards.aspx?hkey=202ff566-4364-4686-b7cl-2a365af59669)and
International Society of Arboriculture BMPs to the extent practicable(e.g.,take care to min-
imize any damage to tree roots and avoid compaction of soil).
• Monitor tree support systems(stakes,guys,etc.).
• Repair and adjust as needed to provide support and prevent tree damage.
• Remove tree supports after one growing season or maximum of 1 year.
• Back-fill stake holes after removal.
• When continued, regular pruning(more than onetime during the growing season)is required
to maintain visual sight lines for safety or clearance along a walk or drive,consider relocating
the plant to a more appropriate location.
• Make reasonable attempts to remove and dispose of class C noxious weeds.
. Re-seed bare turf areas until the vegetation fully covers the ground surface.
• Watch for and respond to new occurrences of especially aggressive weeds such as Him-
alayan blackberry,Japanese knotweed, morning glory, English ivy,and reed canary grass to
avoid invasions.
. Plant and protecttrees per BMP T5.16:Tree Retention and Tree Planting.
. Aerate lawns regularly in areas of heavy use where the soil tends to become compacted. Con-
duct aeration while the grasses in the lawn are growing most vigorously. Remove layers of
thatch greater than 1/4-inch deep.
. Set the mowing height at the highest acceptable level and mow at times and intervals
designed to minimize stress on the turf. Generally mowing only 1/3 of the grass blade height
will prevent stressing the turf.
• Mowing is a stress-creating activity for turfgrass.
• Grass decreases its productivity when mowed too short and there is less growth of
roots and rhizomes.The turf becomes less tolerant of environmental stresses, more dis-
ease prone and more reliant on outside means such as pesticides,fertilizers,and irrig-
ation to remain healthy.
Additional BMP Information:
• King County's Best Management Practices for Golf Course Development and Operation
(King County, 1993)has additional BMPs for Turfgrass Maintenance and Operation.
• King County, Seattle Public Utilities, and the Saving Water Partnership have created the fol-
lowing natural lawn and garden care resources that include guidance on building healthy soil
with compost and mulch,selecting appropriate plants,watering, using alternatives to pesti-
cides,and implementing natural lawn care techniques.
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■ Natural Yard Care-Five steps to make your piece of the planet a healthier place to live
(King County and SPU,2008)
■ The Natural Lawn&Garden Series:Smart Watering(Saving Water Partnership,2006)
■ Natural Lawn Care for Western Washington(Saving Water Partnership,2007)
■ The Natural Lawn& Garden Series:Growing Healthy Soil;Choosing the Right Plants;
and Natural Pest Weed and Disease Control(Saving Water Partnership,2012)
. The International Society of Arboriculture(ISA) is a group that promotes the professional prac-
tice of arboriculture and fosters a greater worldwide awareness of the benefits of trees
through research,technology,and education. ISA standards used for managing trees,
shrubs,and other woody plants are the American National Standards Institute(ANSI)A300
standards.The ANSI A300 standards are voluntary industry consensus standards developed
by the Tree Care Industry Association(TCIA)and written by the Accredited Standards Com-
mittee(ASC).The ANSI standards can be found on the ISA website:www.isa-arbor.-
com/education/publications/index.aspx
. Washington State University's Gardening in Washington State website at http://garden-
ing.wsu.edu contains Washington State specific information about vegetation management
based on the type of landscape.
. See the Pacific Northwest Plant Disease Management Handbook(Pscheidt and Ocamb,
2016)for information on disease recognition and for additional resources.
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S435 BMPs for Pesticides and an Integrated Pest
Management Program
Description of Pollutant Sources: Pesticides include herbicides, rodenticides,insecticides,fun-
gicides, etc. Examples of pesticide uses include:
• Weed control on golf course lawns,access roads, utility corridors and landscaping.
• Sap stain and insect control on lumber and logs.
• Rooftop moss removal.
• Killing nuisance rodents.
• Fungicide application to patio decks.
It is possible to release toxic pesticides such as pentachlorophenol,carbamates,and organo-
metallics to the environment by leaching and dripping from treated parts, container leaks, product
misuse,and outside storage of pesticide contaminated materials and equipment. Poor management
of pesticides can cause appreciable stormwater contamination and unintended impacts to non-tar-
geted organisms.
Pollutant Control Approach: Control of pesticide applications to prevent contamination of storm-
water. Develop and implement an Integrated Pest Management(IPM) Plan.Carefully apply pesti-
cides, in accordance with label requirements.
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Applicable Operational BMPs:
. Train employees on proper application of pesticides and disposal practices.
• Follow manufacturers'application guidelines and label requirements.
. Do not apply pesticides in quantities that exceed the limits on the product the Federal
Insecticide, Fungicide,and Rodenticide Act(FIFRA)label.Avoid excessive application of
chemical.
. Conduct spray applications during weather conditions as specified in the label requirements
and applicable local and state regulations. Do not apply during rain or immediately before
expected rain(unless the label directs such timing).
. Clean up any spilled pesticides immediately. Do not hose down to a storm drain, conveyance
ditch,or water body.
. Remove weeds/vegetation in stormwater ditches,stormwater facilities,and drainage systems
by hand or other mechanical means and only use pesticides as a last resort.
. Flag all sensitive areas including wells,creeks, and wetlands prior to spraying.
• Post notices and delineate the spray area prior to the application,as required by the local jur-
isdiction,or by Ecology.
• Referto S411 BMPsfor Landscaping and Lawn/Vegetation Management and use pesticides
only as a last resort.
. Conduct any pest control activity at the life stage when the pest is most vulnerable. For
example, if it is necessary to use a Bacillus thuringiens application to control tent caterpillars,
apply it to the material before the caterpillars cocoon or it will be ineffective.Any method used
should be site-specific and not used wholesale over a wide area.
. Mix pesticides and clean the application equipment under cover in an area where accidental
spills will not enter surface or ground waters,and will not contaminate the soil.
. The pesticide application equipment must be capable of immediate shutoff in the event of an
emergency.
. Implement a pesticide-use plan and include at a minimum:
• A list of selected pesticides and their specific uses.
• Brands and formulations of the pesticides.
• Application methods and quantities to be used.
• Equipment use and maintenance procedures.
• Safety, storage, and disposal methods.
• Monitoring, record keeping, and public notice procedures.All procedures shall conform
to the requirements of Chapter 17.21 RCW and Chapter 16-228 WAC.
• Develop and implement an Integrated Pest Management(IPM)program if pests are present.
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The following steps are adapted from(Daar, 1992).
• Step One: Correctly identify problem pests and understand their life cycle.
■ Learn more about the pest.
■ Observe it and pay attention to any damage that maybe occurring.
■ Learn about the life cycle.
■ Many pests are only a problem during certain seasons,or can only be treated
effectively in certain phases of the life cycle.
• Step Two: Establish tolerance thresholds for pests.
■ Decide on the level of infestation that must be exceeded before treatment needs
to be considered. Pest populations under this threshold should be monitored but
don't need treatment.
• Step Three: Monitor to detect and prevent pest problems.
■ Monitor regularly to anticipate and prevent major pest outbreaks.
■ Conduct a visual evaluation of the lawn or landscape's condition.Take a few
minutes before mowing to walk around and look for problems.
■ Keep a notebook, record when and where a problem occurs,then monitor for it
at about the same time in future years.
■ Specific monitoring techniques can be used in the appropriate season for some
potential problem pests,such as European crane fly.
• Step Four: Modify the maintenance program to promote healthy plants and dis-
courage pests.
■ Review your landscape maintenance practicesto see if they can be modified to
prevent or reduce the problem.
■ A healthy landscape is resistant to most pest problems. Lawn aeration and over-
seeding along with proper mowing height,fertilization, and irrigation will help the
grass out-compete weeds.
■ Correcting drainage problems and letting soil dry out between waterings in the
summer may reduce the number of crane-fly larvae that survive.
• Step Five: If pests exceed the tolerance thresholds:
■ Consider the most effective management options concurrent with reducing
impacts to the environment.This may mean chemical pesticides are the best
option in some circumstances.
■ Consider the use of physical, mechanical,or biological controls.
■ Study to determine what products are available and choose a product that is the
least toxic and has the least non-target impact.
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Step Six: Evaluate and record the effectiveness of the control, and modify main-
tenance practices to support lawn or landscape recovery and prevent recurrence.
■ Keep records!
■ Note when,where,and what symptoms occurred,or when monitoring revealed
a potential pest problem.
■ Note what controls were applied and when,and the effectiveness of the control.
■ Monitor next year for the same problems.
Recommended Additional Operational BMPs:
. Choose the least toxic pesticide available that is capable of reducing the infestation to accept-
able levels.The pesticide should readily degrade in the environment and/or have properties
that strongly bind it to the soil.
. Choose pesticides categorized by EPA as reduced risk. For example,the herbicide
imazamox.
. When possible,apply pesticides during the dry season so that the pesticide residue is
degraded prior to the next rain event.
. If possible,do not spray pesticides within 100 feet of water bodies.Spraying pesticides within
100 feet of water bodies including any drainage ditch or channel that leads to open water may
have additional regulatory requirements beyond just following the pesticide product label.
Additional requirements may include:
Obtaining a discharge permit from Ecology.
Obtaining a permit from the local jurisdiction.
Using an aquatic labeled pesticide and adjuvant.
• Use manual pest control strategies such as physically scraping moss from rooftops, high-pres-
sure sprayers to remove moss,and rodent traps.
• Consider alternatives to the use of pesticides such as covering or harvesting weeds,sub-
stitute vegetative growth,and manual weed control/moss removal.
. Consider the use of soil amendments, such as compost,that are known to control some com-
mon diseases in plants,such as Pythium root rot,ashy stem blight,and parasitic nematodes.
. Once a pesticide is applied,evaluate its effectiveness for possible improvement. Records
should be kept showing the effectiveness of the pesticides applied.
• Follow the FIFRA label requirements for disposal. If the FIFRA label does not have disposal
requirements the rinseate from equipment cleaning and/or triple-rinsing of pesticide con-
tainers should be used as product or recycled into product.
• Develop an and adaptive management plan and annual evaluation procedure including:
(adapted from(Daar, 1992))
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• A review of the effectiveness of pesticide applications.
• Impact on buffers and sensitive areas,including potable wells. If individual or public pot-
able wells are located in the proximity of commercial pesticide applications,contact the
regional Ecology hydrogeologistto determine if additional pesticide application control
measures are necessary.
• Public concerns.
• Recent toxicological information on pesticides used/proposed for use.
Additional Information
For more information,refer to the Pesticide Information Center Online(PICOL) Databases at
http://cru66.cahe.wsu.edu/LabelTolerance.htmi.
Washington pesticide law requires most businesses that commercially apply pesticides to the prop-
erty of another to be licensed as a Commercial Applicator from the Washington State Department of
Agriculture.
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S450 BMPs for Irrigation
Description of Pollutant Sources: Irrigation consists of discharges from irrigation water lines,
landscape irrigation,and lawn or garden watering. Excessive watering can lead to discharges of
chlorinated potable water runoff into drainage systems;it can also cause erosion;and negatively
affect plant health. Improper irrigation can encourage pest problems,leach nutrients,and make a
lawn completely dependent on artificial watering. Mosquito breeding habitats mayform through
excessive watering.
Pollutant Control Approach: Limit the amount and location of watering to prevent runoff and dis-
charges to drainage systems.
Applicable Operational BMPs:
. Irrigate with the minimum amount of water needed. Never water at rates that exceed the infilt-
ration rate of the soil.
. Maintain all irrigation systems so that irrigation water is applied evenly and where it is needed.
• Ensure sprinkler systems do not overspray vegetated areas resulting in excess water dis-
charging into the drainage system.
• Inspect irrigated areas for excess watering.Adjust watering times and schedules to ensure
that the appropriate amount of water is being used to minimize runoff.Consider factors such
as soil structure,grade,time of year, and type of plant material in determining the proper
amounts of water for a specific area.
. Inspect irrigated areas regularly for signs of erosion and I or discharge.
• Place sprinkler systems appropriately so that water is not being sprayed on impervious sur-
faces instead of vegetation.
. Repair broken or leaking sprinkler nozzles as soon as possible.
. Appropriately irrigate lawns based on the species planted,the available water holding capa-
city of the soil, and the efficiency of the irrigation system.
The depth from which a plant normally extracts water depends on the rooting depth of
the plant.Appropriately irrigated lawn grasses normally root in the top 6 to 12 inches of
soil;lawns irrigated on a daily basis often root only in the top 1 inch of soil.
• Do not irrigate plants during or immediately after fertilizer application.The longer the period
between fertilizer application and irrigation,the less fertilizer runoff occurs.
. Do not irrigate plants during or immediately after pesticide application (unless the pesticide
label directs such timing).
. Reduce frequency and/or intensity of watering as appropriate for the wet season (October 1
to April 30).
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Place irrigation systems to ensure that plants receive water where they need it. For example,
do not place irrigation systems downgradient of plant's root zones on hillsides.
Recommended Operational BMPs:
. Add a tree bag or slow-release watering device(e.g., bucket with a perforated bottom)for
watering newly installed trees when irrigation system is not present.
. Water deeply, but infrequently, so that the top 6 to 12 inches of the root zone is moist.
• Use soaker hoses or spot water with a shower type wand when an irrigation system is not
present.
• Pulse water to enhance soil absorption,when feasible.
• Pre-moisten soil to break surface tension of dry or hydrophobic soils/mulch,followed by
several more passes.With this method,each pass increases soil absorption and allows
more water to infiltrate prior to runoff.
. Identify trigger mechanisms for drought-stress(e.g., leaf wilt, leaf senescence,etc.)of dif-
ferent species and water immediately after initial signs of stress appear.
. Water during drought conditions or more often if necessary to maintain plant cover.
. Adjust irrigation frequency/intensity as appropriate after plant establishment.
. Annually inspect irrigation systems to ensure:
That there are no blockages of sprayer nozzles.
Sprayer nozzles are rotating as appropriate.
Sprayer systems are still aligned with the plant locations and root zones.
. Consult with the local water utility,Conservation District,or Cooperative Extension office to
help determine optimum irrigation practices.
• Do not use chemigation and fertigation in irrigation systems.This will help avoid over applic-
ation of pesticides and fertilizers.
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S436 BMPs for Color Events
Description of Pollutant Sources: Color events are charity,religious, or commercial events that
involve the use of powdered(typically cornstarch based)and/or liquid dyes. Because they typically
occur outside,there is a high likelihood of the color material entering drainage systems and surface
water unless measures are taken to prevent these illicit discharges from occurring.
"Biodegradable"and"non—toxic"do NOT mean that a substance can go into storm drains or water
bodies.The dye material can harm aquatic organisms by altering water quality and chemistry.State
and Federal environmental laws require local jurisdictions to prohibit non-stormwater discharges to
storm drains. Dye material and any wash water are prohibited discharges.
Pollutant Control Approach: Plan for the event.Control the application areas for the powder or
liquid dyes. Block off storm drain inlets prior to the event. Clean up the areas immediately after the
event.
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Figure IV-7.4: Powdered Dyes at Color Events
-y ,7-
. .
�I I
I
yy)\ 1
I `
Color events typically involve the use of powdered dyes such as those pictured.
Powdered Dyes at Color Events
Revised June 2017
DEPARTMENT OF
ECOLOGY Please see http:/{www.ecy.wa.gov/copyright.html for copyright notice including permissions,
State of Washington limitation of liability,and disclaimer.
2019 Stormwater Management Manual for Western Washington
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_ I
Applicable Operational BMPs:
Pre-Event
. Create a map of your event that includes the following:
• Event route.
• Nearby streams, lakes, and ponds.
• Start and finish areas.
• Color application stations/areas.
• Storm drain inlets and open stormwater system features(e.g.,ditches,swales, biore-
tention, rain gardens)at the color application, start and finish areas.
. Create a Pollution Plan that details:
• Measures taken to ensure that NO dye material, either during or after the event,will
enter the drainage system.
• How all dye material will be removed and disposed of.
• What will happen in the event of rain(including addressing localized flooding, runoff,
and collection of the stormwater).
• Emergency numbers for the local city or county in case dye material does enter the
storm drain or water body.
• Use handheld brooms to complete the initial cleanup of paved surfaces. Follow with use of a
vacuum sweeper truck on roads.
. Contract with a commercial street sweeping firm to clean paved surfaces. Have a storm drain
cleaning contractor on—call for discharges to storm drains or emergency clean—up if neces-
sary.
• Ensure that the commercial street sweeping firm has a plan in place for the proper disposal of
sweepings from the event and associated air filters.
• Ensure that all clean-up will be completed prior to the next forecasted rainfall,or no later than
24-hours after the race event, and that the contractor will have enough equipment and staff on
hand for the clean-up.
. Request a copy of the dye product's S IDS (Safety Data Sheet)from the manufacturer or sup-
plier. Review the SIDS for potential safety and environmental hazards.
. Comply with local jurisdiction event permit requirements that contain stormwater pollution pre-
vention BMPs. If no local event permit is required, provide to the local jurisdiction in charge of
stormwater drainage and/or surface water management, in plenty of time(two weeks or
more)prior to the event:
Copies ofthe map
Pollution prevention plan
2019 Stormwater Management Manual for Western Washington
Volume IV-Chapter7-Page 598
• Commercial cleaning contract
• Dye SDSs
• Names and contact information of the event officials for both during and after the event.
Preventing Runoff from Entering Drainage Systems and Water Bodies
. Protect storm drains by using berms,covering the drains,and using catch basin covers.
• Use care when removing berms,covers,and tarps to ensure no dye enters the storm drains.
• Prohibit participants from throwing dye within 100 feet of any stream or other surface water-
body.
. Prohibit participants from throwing dye within 100 feet of any open stormwater feature(e.g,.
ditch,swale, bioretention, rain garden,detention pond)
• Set up color stations at least 100 feet away from any surface water or open stormwater fea-
ture.
. The route,start,finish,and color application stations must be at least 1 00'away from any per-
meable pavement or the permeable pavement must be completely covered.
• If the event will be held on a small,contained area,cordon off the area and place enough cov-
ers on the ground to cover the entire site. If possible, contain the color application to grassy
areas where ground covers are unnecessary.
Event Clean-Up
• Dry off tarps and stained wet pavement with towels or absorbent pads.
• Use brooms or street sweepers to clean up paved areas.The fineness of the material may
require sweepers with dust control systems.
• Do not use blowers to move dye material.
• Do not use hoses or pressure washers to rinse excess dye off of tarps,sidewalks or paved
areas. If it becomes necessary to use water to clean surfaces,all the water must be collected
and disposed of to the sanitary sewer system,with approval from the local sewer agency.
. Call the local spill response hotline immediately(24/7) if any colored water enters a storm
drain or water body.
• Dispose of the collected sweeping materials,cleaning materials,and airfilters appropriately-
. All litter and debris must be picked up and properly disposed of.
. All clean-up must be done within 24-hours of the race event.
2019 Stormwater Management Manual for Western Washington
Volume IV-Chapter 7-Page 599
S442 BMPs for Labeling Storm Drain Inlets On Your
Property
Description of Pollutant Sources:Waste materials dumped into storm drain inlets can have
severe impacts on receiving waters. Posting notices regarding discharge prohibitions at storm drain
inlets can prevent waste dumping. Storm drain signs and stencils are highly visible source controls
that are typically placed directly adjacent to storm drain inlets.
Pollutant Control Approach:The stencil, affixed sign,or metal grate contains a brief statement
that prohibits dumping of improper materials into the urban runoff conveyance system. Storm drain
messages have become a popular method of alerting the public about the effects of and the pro-
hibitions against waste disposal.
Applicable Operational BMPs:
• Label storm drain inlets in residential, commercial, industrial areas, and any other areas
where contributions or dumping to storm drains is likely.
. Stencil or apply storm drain markers adjacent to storm drain inlets to help prevent the
improper disposal of pollutants.Or, use a storm drain grate stamped with warnings against pol-
luting.
. Place the marker in clear sight facing toward anyone approaching the inlet from either side.
• Use a brief statement and/or graphical icons to discourage illegal dumping. Examples
include:
• "No Dumping—Drains to Stream"
• "No Pollutants—Drains to Puget Sound"
• "Dump No Waste—Drains to Lake"
• "No Dumping—Puget Sound Starts Here'
• Check with your local government agency to find out if they have approved specific signage
and/or storm drain message placards for use. Consult the local agency stormwater staff to
determine specific requirements for placard types and methods of application.
• Maintain the legibility of markers and signs. Signage on top of curbs tends to weather and
fade. Signage on face of curbs tends to be worn by contact with vehicle tires and sweeper
brooms.
. When painting stencils or installing markers,temporarily block the storm drain inlet so that no
pollutants are discharged from the labeling activities.
Optional Operational BMPs:
Use a stencil in addition to a storm drain marker or grate to increase visibility of the message.
Reference for thisBMP:(CASQA, 2003)
2019 Stormwater Management Manual for Western Washington
Volume IV-Chapter 7-Page 604
Figure IV-7.6: Storm Drain Inlet Labels
// J 1
' a
1,
Storm Drain Inlet Labels
Revised October 2017
DEPARTMENT OF
ECOLOGY Please see http.Ylwww.ecy.wa.govlcopydght html for copyright notice including permissions,
State of Washingtonj limitation of liability,and disclaimer
2019 Storm we ter Management Manual for Western Washington
Volume IV-Chapter 7-Page 605
S443 BMPs for Fertilizer Application
Description of Pollutant Sources: Poor application of fertilizers can cause appreciable storm-
water contamination. Fertilizers can leach phosphorous,nitrogen,and coliform bacteria. Fertilizers
can contribute to algae blooms, increase nutrient concentrations, and deplete oxygen in receiving
waters.
Pollutant Control Approach: Minimize the amount of fertilizer necessary to maintain vegetation.
Control the application of fertilizer to prevent the discharge of stormwater pollution.
Applicable Operational BMPs:
. Apply the minimum amount of slow-release fertilizer necessary to achieve successful plant
establishment.
• Do not fertilize when the soil is dry or during a drought.
• Never apply fertilizers if it is raining or about to rain.
• Do not apply fertilizers within three days prior to predicted rainfall.The longer the period
between fertilizer application and either rainfall or irrigation,the less fertilizer runoff occurs.
• Determine the proper fertilizer application for the types of soil and vegetation involved.
• Follow manufacturers'recommendations and label directions.
. Train employees on the proper use and application of fertilizers.
• Keep fertilizer granules off impervious surfaces.Clean up any spills immediately. Do not hose
down to a storm drain, conveyance ditch,orwater body.
. If possible,do not fertilize areas within 100 feet of water bodies including wetlands, ponds,
and streams.
. Avoid fertilizer applications in stormwater ditches,stormwater facilities,and drainage sys-
tems.
. In areas that drain to sensitive water bodies, apply no fertilizer at commercial and industrial
facilities,to grass swales,filter strips,or buffer areas unless approved by the local jurisdiction.
. Use slow release fertilizers such as methylene urea, isobutylidene,or resin coated fertilizers
when appropriate,generally in the spring. Use of slow release fertilizers is especially import-
ant in areas with sandy or gravelly soils.
. Apply fertilizers in amounts appropriate for the target vegetation and at the time of year that
minimizes losses to surface and ground waters.
. Time the fertilizer application to periods of maximum plant uptake. Ecology generally recom-
mends application in the fall and spring,although Washington State University turf specialists
recommend four fertilizer applications per year.
• Do not use turf fertilizers containing phosphorous unless a soil sample analysis taken within
2019 Stormwater Management Manual for Western Washington
Volume I V- Chapter 7-Page 606
the past 36 months indicates the soil of the established lawn is deficient in phosphorus. For
more information about restrictions on turffertilizers containing phosphorus,see the following
website:
https://agr.wa.gov/departments/pesticides-and-fertilizers/fertilizerstfertilizers-containing-phos-
hp orus
Recommended Operational BMPs:
Test soils to determine the correct fertilizer application rates.
. Evaluation of soil nutrient levels through regular testing ensures the best possible efficiency
and economy of fertilization.
. Fertilization needs vary by site depending on plant,soil,and climatic conditions.
. Choose organic fertilizers when possible.
. For details on soils testing, contact the local Conservation District, a soils testing professional,
or a Washington State University Extension office.
2019 Stormwater Management Manual for Western Washington
Volume iV-Chapter?-Page 607
i
Ben Root Skate Park
MacKay+sposito 0&M Plan
November 18,2022
Attachment B: Water quality BMP Maintenance Program
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APPENDIX 1 — Survey performed by a Professional Land Surveyor
The object of this appendix is to ensure that the property has a minimum of 3 out of 5 property corners
visible to ensure that the structures are placed within the required setbacks.
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APPENDIX 2 — Soils Anaylsis (Volume 3, Chapter 3.3.2)
Provide the soils report in this appendix
Version Date: August 30, 2022
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USDA Natural Resources Web Soil Survey 10/13/2022
Conservation Service National Cooperative Soil Survey Page 1 of 3
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Map Unit Legend
Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI
I
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8 percent slopes
165 Xerorthents,0 to 5 percent 43.8 50.1%
slopes
Totals for Area of Interest 87.3 100.0%
I
USDA Natural Resources Web Soil Survey 10/13/2022
Conservation Service National Cooperative Soil Survey Page 3 of 3
Geotechnical Engineering Report
Anacortes Skate Park
R Avenue — Parcel No. P77984
Anacortes, Washington 98221
Prepared For:
Grindline Skateparks, Inc.
4619 14th Avenue SW
Seattle, Washington 98106
Gol FT
I8W 251.5276
80,n,ham I Adhnymn I Oak Harbor
www.year<nrinccom
i
GMVT 1.888.251.5276
Bellingham I Arlington I Oak Harbor
Www.geotest-inc.com
March 30, 2022
Project No. 22-0278
Grindline Skateparks, Inc.
4619 14th Avenue SW
Seattle, Washington 98106
Regarding: Geotechnical Engineering Report
Anacortes Skate Park
R Avenue—Parcel No. P77984
Anacortes,Washington 98221
Dear Project Team:
As requested,GeoTest Services, Inc. (GeoTest) is pleased to submit the following report summarizing the
results of our geotechnical engineering evaluation for the proposed Anacortes Skate Park
redevelopment located at the above referenced location in Anacortes,Washington (Vicinity Map, Figure
1). This report has been prepared in general accordance with the terms and conditions established in
our services agreement (Revision 1 Proposal 21-575G) dated December 201h, 2021, and authorized by
Grindline Skateparks.
We appreciate the opportunity to provide geotechnical services on this project and look forward to
assisting you during the construction phases. Should you have any further questions regarding the
information contained within the report, or if we may be of service in other regards, please contact the
undersigned.
Respectfully,
GeoTest Services, Inc. tie of Washi
,tea �r
Englneming aim
"�` `^'�� (T//��^- '� tic 1911 •�h
else Geo\o 3-30-22
HARRISON G. SIMONS
Devin Murphy, G.I.T. Harrison Simons, L.E.G.
Staff Geologist Geotechnical Project Manager
Enclosure: Geotechnical Engineering Report
I
1.888.251.5276
GMWT Bellingham I Arlington I Oak Harbor
v~geotest-inc.com
TABLE OF CONTENTS
PURPOSE AND SCOPE OF SERVICES.....................................................................................................1
PROJECT DESCRIPTION.......................................................................................................................2
SITECONDITIONS...............................................................................................................................2
SurfaceConditions................................................................... ............................................................... 2
SubsurfaceSoil Conditions....................................................................................................................... 3
General Geologic Conditions....................................................................................................................4
Groundwater............................................................................................................................................4
WebSoil Survey........................................................................................................................................ 5
GEOLOGICHAZARDS..........................................................................................................................6
Seismic Hazard Areas—AMC 19.70.415(A)(3) ......................................................................................... 6
Volcanic Hazard Areas—AMC 19.70.415(A)(5).........................................................................................7
CONCLUSIONS AND RECOMMENDATIONS..........................................................................................8
Site Preparation and Earthwork............................................................................................................... 9
Filland Compaction................................................................................................................................... 9
Reuseof On-Site Soil.......................................................................................................................... 10
StructuralFill....................................................................................................................................... 10
Backfilland Compaction .................................................................................................................... 10
WetWeather Earthwork........................................................................................................................ 11
Seismic Design Considerations............................................................................................................... 11
FoundationSupport............................................................................................................................... 12
AllowableBearing Capacity............................................................................................................... 12
FoundationSettlement...................................................................................................................... 12
SlabSupport........................................................................................................................................... 13
Foundationand Site Drainage................................................................................................................ 13
Resistance to Lateral Loads.................................................................................................................... 14
Temporaryand Permanent Slopes ........................................................................................................ 15
Utilities................................................................................................................................................... 15
Pavement Subgrade Preparation........................................................................................................... 16
Flexible Pavement Sections—Light Duty........................................................................................... 16
Flexible Pavement Sections—Heavy Duty......................................................................................... 16
ConcretePavement Sections............................................................................................................. 17
Stormwater Infiltration Potential...........................................................................................................17
Geotechnical Consultation and Construction Monitoring..................................................................... 18
USEOF THIS REPORT........................................................................................................................18
REFERENCES ....................................................................................................................................20
GeoTest Services, Inc. March 30, 2022
Anacortes Skate Park—Anacortes,Washington Project Number:22-0278
PURPOSE AND SCOPE OF SERVICES
The purpose of this evaluation is to establish general surface and subsurface conditions at the
site from which conclusions and recommendations pertaining to project design can be
formulated. Our scope of services includes the following tasks:
• Exploration of the soil and groundwater conditions underlying the project site by
advancing 5 geotechnical soil borings with a drilling contractor subcontracted through
GeoTest.
• Laboratory testing on representative samples to classify and evaluate the engineering
characteristics of the soils encountered.
• Provide a written report containing a description of surface and subsurface conditions,
exploration logs, with findings and recommendations pertaining to site preparation and
grading activities, including stripping depths, subgrade preparation below planned
structural elements, reuse of onsite soils, and criteria for selection, placement, and
compaction of structural fill.
• Provide a preliminary assessment of the on-site infiltration feasibility in general
accordance with the 2014 Stormwater Management Manual for Western Washington.
• Provide recommendations for foundation support of planned concrete structures and
slabs including subgrade preparation, allowable soil bearing pressures, bearing
elevations, frost penetration and depth, estimates of settlement, subsurface drainage,
parameters for lateral load resistance, subgrade modulus values and friction coefficients
to be used between concrete structures and subgrades soils and pavement sections for
both light and heavy-duty traffic.
• A discussion of the Seismic Site Class considerations based on the 2018 International
Building Code (IBC).
• Discussion of geologic hazards and potential mitigation, if applicable, in compliance with
City of Anacortes Municipal Code (AMC). Chapter 19.70.410 — 19.70.435, Geologically
Hazardous Areas.
• Discussion of excavation considerations including recommendations for allowable
excavation slope inclinations for temporary and permanent slopes, classification of soil
types per OSHA regulations,geotechnical consulting, and construction monitoring.
1
GeoTest Services, Inc. March 30, 2022
Anacortes Skate Park—Anacortes,Washington Project Number:22-0278
PROJECT DESCRIPTION
Based on conversations with our client, we understand that there are preliminary plans to
demolish the existing Anacortes skate park and parking facilities to allow for the construction of
new,enlarged parking lot and a new, roughly 10,000 to 15,000 square foot skate park within the
same general area.The new parking lot is likely to be cited to the south of the existing skate park
location, which was constructed in the early 2000's. New skate park surfaces would be
constructed of reinforced concrete. As such, we anticipate that loading conditions will be
relatively light in scale.
SITE CONDITIONS
This section includes a description of the general surface and subsurface conditions observed at
the project site during the time of our field investigation. Interpretations of site conditions are
based on the results and review of available information, site reconnaissance, subsurface
explorations, laboratory testing, and previous experience in the project vicinity. Site conditions
were observed and documented by a GeoTest Staff Geologist on March 7th, 2022.
Surface Conditions
The subject area exists within Alice Parchman Newland Park, to the southeast of the 22nd Street
and R Avenue roundabout in Anacortes, Washington. The project site is bound to the west by R
Avenue, to the east by a pedestrian path, sparse commercial development, and the Anacortes
Marina. Generally undeveloped land which is surfaced by asphalt, concrete and what appears to
be landscaped vegetation borders the project site to the south. The site is currently occupied by
the Ben Root skate park and associated parking areas. Topography slopes down gently towards
the northeast,with only a few feet of vertical relief across the lateral extent of the site. No surface
water was observed on-site at the time of our site visit.
I
I i
Image 1(left).General
site overview with the
Ben Root Skate Parkin the
foreground.Perspective is.
�7� 1iy,F facing south from the
edge of existing parking
IF facilities.
2
GeoTest Services, Inc. March 30, 2022
Anacortes Skate Park—Anacortes,Washington Project Number:22-0278
Subsurface Soil Conditions
Subsurface conditions were explored by advancing five hollow-stem auger borings (B-1 through
B-5) on March 7th, 2022.. The explorations were advanced to depths of 14 feet below ground
surface (BGS) with a subcontracted drill rig under the direction of a GeoTest Staff Geologist. Soil
classification followed the guidelines of the American Society for Testing and Materials (ASTM)
D2487 and D2488. Exploration locations were limited to the perimeter of the existing skate park,
as such,the conditions below existing hardscapes is unknown at this time,Approximate locations
of these explorations have been plotted on the Site and Exploration Plan (Figure 2). A Soil
Classification System and Key is presented as Figure 4. Detailed exploration logs can be found in
Figures 5 through 9—Boring Logs, with laboratory results as Figure 10.
x�
Image 2(above).Subsurface soil sample of a sandy clay obtained from boring 0-1 at 7.5 feet BGS.
Disturbed but representative samples were obtained by using the Standard Penetration Test
(SPT) procedure in accordance with ASTM D1586 during drilling operations. This test and
sampling method consists of driving a standard 2-inch outside diameter, split-barrel sampler a
distance of 18 inches into the soil with a 140-pound hammer free-falling a distance of 30 inches.
The number of blows for each 6-inch interval is recorded and the number of blows required to
drive the sampler the final 12 inches is known as the Standard Penetration Resistance ("N") or
blow count. If a total of 50 blows is recorded within one 6-inch interval, the blow count is
recorded as the number of blows for the corresponding penetration, measured in inches. The
resistance or N-value provides a measure of the relative density of granular soils (sands and
gravels) or the relative consistency of cohesive soils (silts and clays); these values are reported
on the attached boring logs.
3
GeoTest Services,Inc. March 30, 2022
Anacortes Skate Park—Anacortes,Washington Project Number: 22-0278
Subsurface soil conditions were observed to be generally consistent throughoutthe explorations.
Near surface soil conditions consisted of approximately 1 to 2 feet of loose, dark brown, slightly
gravelly, damp to moist, silty sand (import fill and topsoil mix) topped with a thin layer of sod.
Underlying the topsoil/fill was medium stiff to stiff, damp to moist, gray to brown, slightly
gravelly,sandy claythat was interpreted as native glaciomarine drift and extended to the planned
termination depths of the explorations.
Although regional artificial fill materials are mapped within the immediate vicinity of the project
site, no evidence of these soils were observed within our subsurface explorations.
General Geologic Conditions
General geologic conditions were obtained from the Geologic map of the Bellingham 1:100,000
quadrangle, Washington (Lapen, T.J., 2000). Based on this map, the project site falls along a
mapped contact between Artificial Fill materials (Of) and Glaciomarine Drift (Qgdme). The fill
materials are generally mapped to the east of the project site, while Glaciomarine Drift deposits
are mapped to the west.
Artificial Fill is composed of earth debris, demolition debris, and locally, refuse disposed of as
solid waste.Thickness is generally more than 2 meters. (Lapen, 2000)
Glaciomarine Drift deposits are composed of moderately to poorly indurated, moderately to
unsorted diamicton with lenses and discontinuous beds of moderately to well-sorted gravel,
sand, silt, and clay. Dropstone content is variable, and they are commonly polished, striated,and
(or) faceted. Bedding is generally massive to poorly stratified in marine sediments and locally
cross-bedded in sandy interbeds.Glaciomarine Drift was deposited during the Everson Interstade
of the Fraser Glaciation, approximately 12,600 to 13,000 years ago. Sediments of clay, silt, and
sand were released by the melting of floating ice and deposited along the seafloor(Lapen,2000).
The native soils encountered across the project site in our subsurface explorations appear to be
consistent with the mapped unit description of Glaciomarine Drift deposits, as described above.
The site is approximately 9.25 miles north of the Devil's Mountain Fault Zone (DMFZ), a left-
lateral oblique slip fault system which is considered active bythe DNR.Accordingto the published
literature, the DMFZ has been active as recent as 100 to 500 years ago and has the potential for
a magnitude 7.5 earthquake or greater (Barrie, 2017). No landslides are mapped within the
vicinity of the project site.
Groundwater
Groundwater was not encountered during our explorations. A review of the Washington State
Department of Ecology(DOE) Well Report Viewer indicates that groundwater wells in the vicinity
4
GeoTest Services, Inc. March 30, 2022
Anacortes Skate Park—Anacortes,Washington Project Number: 22-0278
of the project site encountered groundwater levels ranging from 30 to 48 feet BGS at time of
installation.
However, perched groundwater conditions are expected to develop at the project site during the
wet season and/or following periods of extended precipitation. Perched groundwater conditions
occur above the regional groundwater table in the unsaturated zone and typically occur when
loose, more permeable soil is underlain by denser, less permeable soil.The vertical movement of
water through loose soils is restricted once a dense or less permeable soil is encountered at
depth. Perched groundwater conditions typically develop in the wet season (November through
April) or after extended periods of rainfall.
The groundwater conditions reported on the exploration logs are for the specific locations and
dates indicated and therefore may not be indicative of other locations and/or times.
Groundwater levels are variable and groundwater conditions will fluctuate depending on local
subsurface conditions, precipitation, and changes in on-site and offsite use.
Web Soil Survey
According to the United States Department of Agriculture(USDA) Natural Resource Conservation
Service (NRCS) Web Soil Survey website, one relevant soil unit is present on the subject property.
Please reference Table 1 below for general characteristics. Based on their erosion "K" factor
assigned by the NRCS, the soils present on-site are considered to be "highly" to "severely"
susceptible to erosion. Values of the erosion factor "K" range from 0.02 to 0.69; the higher the
value, the more susceptible the soil is to sheet and rill erosion by water.
Table 1
USDA NRCS Soil Classifications
Map Unit Symbol 165
Map Unit Name Xerorthents,0 to 5 percent slopes
General Location Site entirety
Soil Description Variable over stratified extremely gravelly sandy loam
Landform Flood plains, hillslopes
Parent Material Human transported and disturbed material
Land Capability Classification 7e
Erosion K Factor,Whole Soil 0.10I,
5
GeoTest Services, Inc. March 30,2022
Anacortes Skate Park—Anacortes,Washington Project Number:22-0278
The soils found within the project vicinity are considered as having "very low" susceptibility to
erosion based on their K Factor ratings and lack of sloping terrain in the project vicinity.
GEOLOGIC HAZARDS
According to Anacortes Municipal Code (AMC) section 19.70.410(a), Geologically hazardous
areas include "areas susceptible to the effects of erosion, landslides, earthquakes or other
geologic events. They pose a threat to health and safety of citizens when incompatible
development is sited in areas of significant hazard." Anacortes code goes on to define erosion,
landslide, seismic, mine, volcanic, tsunami and other hazards (including mass wasting, debris
flows, rockfalls,and differential settlement). Hazards which are considered to be relevant and/or
present at the project site are discussed within the following sections. Based on our review,
landslide hazards, erosion hazards, mine hazards, tsunami hazards, and "other hazards", as
defined by AMC are not present at the project site.
Seismic Hazard Areas—AMC 19.70.415(A)(3)
Anacortes Municipal Code section 19.70.415(A)(3) defines seismic hazards as "lands that, due to
a combination of soil and groundwater conditions, are subject to risk of damage as a result of
earthquake-induced ground shaking,slope failure, settlement or subsidence, soil liquefaction,or
surface faulting."
According to the DNR Geologic Information Portal, the eastern most portion of the project site
contains a mapped contact between Low to Moderate (western portion of project site) and High
liquefaction susceptibility(eastern portion of project site).This map only provides an estimate of
the likelihood that soil will liquify as a result of an earthquake and is meant as a general guide to
delineate areas prone to liquefaction.
The discussion section within the Liquefaction Susceptibility and Site Class Maps of Washington
State by County (Palmer et al., 2004) clarifies that the mapped liquefaction hazards are based
solely on the 1:100,000 scale surficial geologic maps published by the DNR. In this case, the
liquefaction susceptibility map identifies the site as containing Artificial Fill, which is subject to
liquefaction resulting from earthquake shaking. As addressed in the General Geologic Conditions
section of this report, our field observations lead us to believe that the 1:100,000 scale geologic
map published by Lapen, et al., is not entirely representative of the conditions at the project site.
Based on our boring explorations, we interpret the site to be underlain by Glaciomarine Drift.As
such, we will be referring to the seismic hazard conditions for the appropriate soil unit —
Glaciomarine Drift--for use in this hazard assessment.
Liquefaction is defined as a significant rise in pore water pressure within a soil mass caused by
earthquake-induced cyclic shaking. The shear strength of liquefiable soil is reduced during large
and/or long duration earthquakes as the soil consistency approaches that of semi-solid slurry.
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Liquefaction can result in significant and widespread structural damage if not properly mitigated.
Deposits of loose,granularsoil belowthe groundwater table are most susceptible to liquefaction.
Damage due to foundation rotation, lateral spreading, and other ground movements can result
from soil liquefaction.
The project site appears to be entirely underlain by fine grained Glaciomarine Drift deposits.
Moreover, no evidence of artificial fill soils, associated with the regional fill to the east of the
project site (aside from the near surface topsoil and fill soils, reflective of historic, near surface
site development) was encountered within any of our subsurface explorations. Furthermore,
groundwater representative of the regional groundwater table or potentiometric surface was not
observed within any of our subsurface explorations. As such, the subsurface conditions across
the collective project site appear to support the Low to Moderate liquefaction susceptibility
rating as mapped to the west of the site. Based on the results of our investigation,the potential
for liquefaction susceptibility across the entire subject area appears to be low to moderate. In
our professional opinion, the high liquefaction susceptibility area, as generally mapped by the
Department of Natural Resources to the east of the subject area, is not applicable to the geologic
materials observed below the project site.
Thus,the subject property is not considered to be a seismic hazard area. As such, no additional
mitigations other than IBC requirements for seismic design category D1 will be required for the
proposed development. No active faults are mapped in the immediate vicinity of the planned
improvements.
Volcanic Hazard Areas—AMC 19.70.415(A)(5)
Anacortes Municipal Code section 19.70.415(A)(5)defines volcanic hazard areas as"areas subject
to pyroclastic flows, lava flows, debris avalanche, and inundation by debris flows, lahars,
muciflows, or related flooding resulting from volcanic activity. Though there are no significant
risks identified for the city and immediate surrounding area, other than airborne particulate
impacts from an eruption."
The DNR does not consider the subject property to be at risk from lahars, pyroclastic flows, lava
flows, ballistic projectiles or volcanic landslides. However,the locations of ash/tephra fall hazards
from Mount Baker and Glacier Peak are predominantly controlled by the prevailing westerly
winds observed on the west coast of North America. Easterly winds do occur in the region and
direct ash/tephra fall impacts to the City of Anacortes are certainly a possibility. Health hazards,
power outages, negative impacts to machinery and aircraft, structural damage (e.g., roof
collapse)and extensive disruption of daily activities are all potential hazards.Due to the potential
ash and tephra fall hazards that are present, the subject area is considered to fall within a
volcanic hazard area.
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Depending on the amount of ash fall generated from a potential eruption, ash fall may amount
to little more than an inconvenience. It is our opinion, however,that the property owners should
be aware of this potential hazard.
If a volcanic eruption were to occur at Mount Baker or Glacier Peak for example, the DNR
recommends the immediate implementation of the following protocol:
• Listen carefully to official reports via emergency broadcasts.
• If officials warn of an approaching lahar, seek high ground off the valley floor as quickly
as possible, such as moving up a hillside.Then, seek shelter.
• Stay out of valleys and low-lying areas that lead away from the mountain.
• Evacuate if necessary.
CONCLUSIONS AND RECOMMENDATIONS
Based on the evaluation of the data collected during this investigation, it is our opinion that the
subsurface conditions at the site are suitable for the proposed recreational development,
provided the recommendations contained herein are incorporated into the project design.
GeoTest generally anticipates about 1 to 2.5 feet of stripping will be needed to remove topsoil
and near surface fill soils in order to expose the native upper glaciomarine drift soil below the
planned development areas. It should be noted, however,that boring explorations accomplished
as part of this study were advanced around the perimeter of the existing skatepark surfaces. We
assume that the encountered soil conditions in these locations are generally representative of
the conditions below the existing skatepark, however, some variation should generally be
anticipated. Once competent native soils have been exposed, GeoTest recommends that the
subgrade surface be compacted to a firm and unyielding condition with an appropriate piece of
construction equipment.The proposed skate park and associated access roads and parking areas
can then bear directly on compacted structural fill placed atop approved native soils. Further
recommendations regarding the placement and compaction of structural fill can be found in the
Fill and Compaction section of this report.
GeoTest generally encountered stiff to very stiff sandy clay within the shallow subsurface across
the project site. Due to the impermeable nature of this soil, conventional stormwater infiltration
does not appear to be feasible at the project site. It is our opinion that Pilot Infiltration Testing,
as detailed within the Optional Services section of our original service agreement, should not be
performed at the project site.We expect that stormwater management will be accomplished via
engineered design or be directed towards a municipally approved discharge location.
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Site Preparation and Earthwork
The portions of the site proposed for slabs, pavements and foundations should be prepared by
removing existing topsoil,fill soil,deleterious material,and significant accumulations of organics.
We anticipate stripping depths of approximately 1 to 2.5 feet below existing site grades will be
required to expose inorganic, native glaciomarine drift materials. Increased thicknesses of
previously placed fill materials could be encountered below existing skate park hardscapes. Prior
to placement of any foundation elements or structural fill, the exposed subgrade under all areas
to be occupied by soil-supported slabs, spread, or continuous foundations should be
recompacted to a firm and unyielding condition.Verification of compaction should be performed
by qualified geotechnical personnel, as discussed below. The purpose of this effort is to identify
loose or soft soil deposits so that, if feasible, the soil disturbed during site work can be
recompacted.
Proof rolling should be carefully observed by qualified geotechnical personnel. Areas exhibiting
significant deflection, pumping, or over-saturation that cannot be readily compacted should be
overexcavated to firm soil. Overexcavated areas should be backfilled with compacted granular
material placed in accordance with subsequent recommendations for structural fill. During
periods of wet weather, proof rolling could damage the exposed subgrade. Under these
conditions,qualified geotechnical personnel should observe subgrade conditions to determine if
proof rolling is feasible.
Proof rolling may not be feasible for certain locations within excavations, trench areas, or other
difficult access zones when using a full-size dump truck or other large machinery. In this situation,
we recommend alternate means of verification such as Dynamic Cone Penetrometer (DCP)
testing or soil probe methods be employed to verify suitability of field conditions.
Fill and Compaction
Structural fill used to obtain final elevations for footings and soil-supported slabs must be
properly placed and compacted. In most cases,any non-organic, predominantly granular soil may
be used for structural fill material provided the material is properly moisture conditioned prior
to placement and compaction, and the specified degree of compaction is obtained. Material
containing topsoil, wood, trash, organics, or construction debris is not suitable for reuse as
structural fill and should be properly disposed offsite or placed in nonstructural areas.
Soils containing more than approximately 5 percent fines are considered moisture sensitive and
are difficult to compact to a firm and unyielding condition when over the optimum moisture
content by more than approximately 2 percent. The optimum moisture content is that which
allows the greatest dry density to be achieved at a given level of compactive effort.
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Reuse of On-Site Soil
Due to variable fines content and organic content of the on-site soils, this material is not
recommended for use as structural fill due to the difficulties associated with moisture
conditioning. GeoTest recommends any reuse of the native soils be limited to landscape and
other non-structural areas. If practical quantities of previously placed fill materials are
encountered below existing skate park surfaces, GeoTest would be please to evaluate this
material for use as structural fill, upon request.
Structural Fill
GeoTest recommends that imported structural fill consist of clean, well-graded sandy gravel,
gravelly sand, or other approved inorganic, naturally occurring granular material (pit run) or a
well-graded crushed rock. We recommend structural fill for dry weather construction be similar
to Washington State Department of Transportation (WSDOT) Standard Specification 9-03.14(2)
for "Select Borrow"with the added requirement than 100 percent pass a 4-inch-square sieve.
Soil containing more than about 5 percent fines (that portion passing the U.S. No. 200 sieve)
cannot consistently be compacted to a dense, non-yielding condition when the water content is
greater than optimum. Accordingly, GeoTest recommends that imported structural fill for wet
weather construction be similar to WSDOT Standard Specification 9-03.14(1)for"Gravel Borrow"
with the added requirement that no more than 5 percent pass the U.S. No.200 sieve. Due to wet
weather or wet site conditions, soil moisture contents could be high enough that it may be very
difficult to compact even 'clean' imported select granular fill to a firm and unyielding condition.
Soils with over-optimum moisture contents should be scarified and dried back to more suitable
moisture contents during periods of dry weather or removed and replaced with fill soils at a more
suitable range of moisture contents.
Based on local availability,the designer may electto utilize Crushed Surfacing Base Course(CSBC)
or Crushed Surfacing Top Course(CSTC)as structural fill. In our opinion,clear crush rock products
are preferred for the support of the planned skate park structures, we recommend gradations
similar to WSDOT Standard Specification 9-03.9(3), with the added requirement that little to no
material passing the No. 200 sieve, be incorporated into the project plans.
Backfill and Compaction
Structural fill should be placed in horizontal lifts.The structural fill should measure 8 to 10 inches
in loose thickness and be thoroughly compacted.All structural fill placed under load bearing areas
should be compacted to at least 95 percent of the maximum dry density, as determined using
test method ASTM D1557. The top of the compacted structural fill should extend outside all
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foundations and other structural improvements a minimum distance equal to the thickness of
the fill. We recommend that compaction be tested after placement of each lift in the fill pad.
Wet Weather Earthwork
The near surface glaciomarine drift soils can be susceptible to degradation during wet weather.
As a result, it may be difficult to control the moisture content of site soils during the wet season.
If construction takes place during wet weather, GeoTest recommends that structural fill consist
of imported, clean, well-graded gravelly sand or sandy gravel as described above. If fill is to be
placed or earthwork is to be performed in wet conditions, the contractor may reduce soil
disturbance by:
• Limiting the size of areas that are stripped of topsoil and left exposed
• Accomplishing earthwork in small sections
• Limiting construction traffic over unprotected soil
• Sloping excavated surfaces to promote runoff
• Limiting the size and type of construction equipment used
• Providing gravel 'working mats' over areas of prepared subgrade
• Removing wet surficial soil prior to commencing fill placement each day
• Sealing the exposed ground surface by rolling with a smooth drum compactor or rubber-
tired roller at the end of each working day
• Providing up-gradient perimeter ditches or low earthen berms and using temporary
sumps to collect runoff and prevent water from ponding and damaging exposed
subgrades
Seismic Design Considerations
The Pacific Northwest is seismically active, and the site could be subject to movement from a
moderate or major earthquake. Consequently, moderate levels of seismic shaking should be
accounted for during the design life of the project, and the proposed structure should be
designed to resist earthquake loading using appropriate design methodology.
For structures designed using the seismic provisions of the 2018 International Building Code, the
glaciomarine drift material underlying the site within the upper approximately 100 feet is
classified as Site Class D, according to ASCE 7-16. The structural engineer should select the
appropriate design response spectrum based on Site Class D soil and the geographical location
of the proposed development.
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Foundation Support
We recommend that concrete flat work and continuous or spread footings for any potentially
planned, lightly loaded structures be founded on 12 inches of properly compacted structural fill
placed directly over approved native soil to provide uniform support for the proposed
improvements. We also recommend that qualified geotechnical personnel from our firm verify
that suitable bearing conditions have been reached prior to placement of structural fill or
foundation formwork. When placed below any potential foundations or concrete flat work
construction, structural fill materials should extend laterally beyond the edge of each side of the
footing (or structure) a distance equal to the depth of the excavation below the base of the
footing.
To provide proper support, GeoTest recommends that existing topsoil, existing fill (if present),
and/or loose upper portions of the native soil be removed from beneath improved area(s) or be
replaced with properly compacted structural fill as described in the Fill and Compaction section
of this report. Localized overexcavation, if necessary, can be backfilled to the design footing
elevation with structural fill. In areas requiring overexcavation to competent native soil,the limits
of the overexcavation should extend laterally beyond the edge of each side of the footing a
distance equal to the depth of the excavation below the base of the footing if using structural fill.
In addition, GeoTest recommends that foundation elements for the proposed structure(s) bear
entirely on similar soil conditions to help prevent differential settlement from occurring.
Continuous and isolated spread footings should be founded 18 inches, minimum, below the
lowest adjacent final grade for freeze/thaw protection. The footings should be sized in
accordance with the structural engineer's prescribed design criteria and seismic considerations.
Allowable Bearing Capacity
Assuming the above foundation support criteria are satisfied, continuous or isolated spread
footings founded on one foot of structural fill atop recompacted native soil may be proportioned
using a net allowable soil bearing pressure of 2,000 pounds per square foot (psf).
The "net allowable bearing pressure" refers to the pressure that can be imposed on the soil at
foundation level. This pressure includes all dead loads, live loads,the weight of the footing, and
any backfill placed above the footing. The net allowable bearing pressure may be increased by
one-third for transient wind or seismic loads.
Foundation Settlement
Settlement of shallow foundations depends on foundation size and bearing pressure, as well as
the strength and compressibility characteristics of the underlying soil. If construction is
accomplished as recommended and at the maximum allowable soil bearing pressure, GeoTest
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estimates the total static settlement of Skatepark foundations to be less than one inch.
Differential settlement between two adjacent load-bearing components supported on
competent soil is estimated to be less than one half the total settlement.
Slab Support
Conventional slab-on-grade construction is considered feasible for the planned site
improvements. Concrete flatwork may be supported on a minimum of 12 inches of properly
placed and compacted structural fill placed overproperly prepared native soil. Priorto placement
of the structural fill, the native soil should be verified as suitable as recommended in the Site
Preparation and Earthwork section of this report.
For exterior concrete slabs-on-grade used as skate park features,parking or sidewalk areas, long-
term performance will be enhanced if concrete is placed on at least a 6 inch layer of clean,
durable, well-draining granular material as recommended herein.
A Subgrade Modulus (k) of 200 pounds per cubic inch (pci) is recommended for use in design of
concrete slab elements. This value is assuming site preparations prior to slab installation follow
the minimum soil preparation measures recommendation above, including the recompaction of
existing native soil, as discussed.
Foundation and Site Drainage
Positive surface gradients should be provided adjacent to the proposed concrete flat work
construction and any structures to direct surface water away from the proposed improvements
and toward suitable drainage facilities. Pavement and sidewalk areas, if present,should be sloped
and drainage gradients should be maintained to carry surface water away from the proposed
improvements towards an approved stormwater collection system. We generally assume that
drainage will be managed through conveyance to a municipally approved outlet and may consist
of a central drain within the skate park interior to collect the majority of surface waters created
by the proposed improvements. Surface water should not be allowed to pond and soak into the
ground surface near buildings or paved areas during or after construction. Construction
excavations should be sloped to drain to sumps where water from seepage, rainfall, and runoff
can be collected and pumped to a suitable discharge facility.
Although new buildings are not currently planned as part of the proposed site improvements,
GeoTest expects that bathrooms or other relatively small and lightly loaded structures could be
incorporated into the plan for development at the project site. If that is the case, roof drainage
should not be introduced into the perimeter footing drains but should be separately discharged
directly to the stormwater collection system or similar municipality-approved outlet. Further, to
reduce the potential for groundwater and surface water to seep into interior spaces, GeoTest
recommends that an exterior footing drain system be constructed around the perimeter of any
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new lightly loaded building foundations as shown in the Conceptual Footing and Wall Drain
Section (Figure 3)of this report.The drain should consist of a perforated pipe measuring 4 inches
in diameter at minimum, surrounded by at least 12 inches of filtering media. The pipe should be
sloped to carry water to an approved collection system.
The filtering media may consist of open-graded drain rock wrapped in a nonwoven geotextile
fabric such as Mirafi 140N (or industry equivalent). For foundations supporting retaining walls,
drainage backfill should be carried up the back of the wall and be at least 12 inches wide. The
drainage backfill should extend from the foundation drain to within approximately 1 foot of the
finished grade and consist of open-graded drain rock containing less than 3 percent fines by
weight passing the U.S. Standard No. 200 sieve (based on a wet sieve analysis of that portion
passing the U.S. Standard No. 4 sieve). The invert of the footing drain pipe should be placed at
approximately the same elevation as the bottom of the footing or 12 inches below the adjacent
floor slab grade, whichever is deeper, so that water will be contained. This process prevents
water from seeping through walls or floor slabs. The drain system should include cleanouts to
allow for periodic maintenance and inspection.
Please understand that the above recommendations are intended to assist the design engineer
and/or architect in development of foundation and site drainage parameters and are based on
our experience with similar projects in the area. The final foundation and site drainage plan that
will be incorporated into the project plans is to be determined by the design team.
Resistance to Lateral Loads
Passive earth pressures developed against the sides of foundations, in conjunction with friction
developed between the base of the footings and the supporting subgrade,will resist lateral loads
transmitted from the structure to its foundation. For design purposes, the passive resistance of
well-compacted fill placed against the sides of foundations is equivalent to a fluid with a density
of 225 pcf, which is representative of saturated conditions. The recommended value includes a
safety factor of about 1.5 and assumes that the ground surface adjacent to the structure is level
in the direction of movement for a distance equal to orgreaterthan twice the embedment depth.
The recommended value also assumes drained conditions that will prevent the buildup of
hydrostatic pressure in the compacted fill. If future plans call for the removal of the soil providing
resistance, the passive resistance should not be considered.
An allowable coefficient of base friction of 0.35, applied to vertical dead loads only, may be used
between the underlying imported granular structural fill and the base of the footing.
If passive and frictional resistance are considered together, one half the recommended passive
soil resistance value should be used since larger strains are required to mobilize the passive soil
resistance as compared to frictional resistance.A safetyfactor of about 1.5 is included in the base
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friction design value. GeoTest does not recommend increasing the coefficient of friction to resist
seismic or wind loads.
Temporary and Permanent Slopes
The contractor is responsible for construction slope configurations and maintaining safe working
conditions, including temporary excavation stability.All applicable local,state,and federal safety
codes should be followed. All open cuts should be monitored during and after excavation for any
evidence of instability. If instability is detected, the contractor should flatten the side slopes or
install temporary shoring.
Temporary excavations in excess of 4 feet should be shored or sloped in accordance with Safety
Standards for Construction Work Part N, WAC 296-155-66403. Temporary unsupported
excavations in the loose sandy soils encountered within the upper roughly 1 to 2 feet at the
project site are classified as a Type C soil according to WAC 296-155-66401 and may be sloped as
steep as 1.5:1(Horizontal:Vertical). However,excavations advanced into medium stiff orgreater,
fine grained Glaciomarine Drift soils will be classified as Type B soils and may be sloped as steep
as as 1:1 (Horizontal: Vertical) according to the same WAC standards. All soils encountered are
classified as Type C soil in the presence of groundwater seepage. Flatter slopes or temporary
shoring may be required in areas where groundwater flow is present and unstable conditions
develop.
Temporary slopes and excavations should be protected as soon as possible using appropriate
methods to prevent erosion from occurring during periods of wet weather.
GeoTest recommends that permanent cut or fill slopes be designed for inclinations of 2H:1V or
flatter. Permanent cuts or fills used in detention ponds,retention ponds,or earth slopes intended
to hold water should be 3H:1V or flatter.All permanent slopes should be vegetated or otherwise
protected to limit the potential for erosion as soon as practical after construction.
Utilities
Utility trenches must be properly backfilled and compacted to reduce cracking or localized loss
of foundation, concrete flat work or pavement support. Excavations for new shallow
underground utilities are expected to be placed within native drift soils. Trench backfill in
improved areas (beneath structures, concrete flat work, pavements, sidewalks, etc.) should
consist of structural fill as defined in the Fill and Compaction section of this report. Outside of
improved areas, trench backfill may consist of reused native material provided the backfill can
be compacted to the project specifications. Trench backfill should be placed and compacted in
general accordance with the recommendations presented in the Fill and Compaction section of
this report.
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Surcharge loads on trench support systems due to construction equipment, stockpiled material,
and vehicle traffic should be included in the design of any anticipated shoring system. The
contractor should implement measures to prevent surface water runoff from entering trenches
and excavations. In addition, vibration resulting from construction activity adjacent to
excavations may cause caving of the trench walls.
The contractor is responsible for trench configurations. All applicable local, state, and federal
safety codes should be followed. All open cuts should be monitored by the contractor during
excavation for any evidence of instability.
If instability is detected,the contractor should flatten the side slopes or install temporary shoring.
If groundwater or groundwater seepage is present, and the trench is not properly dewatered,
the soil within the trench zone may be prone to caving, channeling, and running.Trench widths
may become substantially wider than under dewatered conditions.
Pavement Subgrade Preparation
The following recommendations are intended as typical pavement recommendations that may
be incorporated into roadways or access lanes expected to encompass the new development.
The final design will be performed by the civil engineer / skate park designer. We recommend
stripping of all organic soil and removal of any existing fill or construction debris down to
competent native soil prior to the placement of the new roadway fill. The following
recommendations are meant as a guideline for the design engineer to develop final pavement
sections in accordance with current codes and standards. For pavement design purposes we
recommend using a CBR value of 10 for the near surface, stiff native glaciomarine drift soils.
Flexible Pavement Sections—Light Duty
If utilized within light vehicle parking areas,we recommend a standard, or"light duty", pavement
section consist of 2.5 inches of Class %-inch HMA asphalt above 2 inches of Crushed Surfacing
Top Course (CSTC) meeting criteria set forth in the Washington State Department of
Transportation (WSDOT)Standard Specification 9-03.9(3).The base material for the road section
should consist of"gravel base" which may include 8 inches of gravel borrow (with 100% passing
the 2-inch sieve) or 6 inches of Crushed Surfacing Base Course (CSBC) as classified by WSDOT 9-
03.9(3)Standards and Specifications.
Flexible Pavement Sections—Heavy Duty
New driveways, parking or and any other areas that will be accessed by heavy traffic or higher
volumes,such as fire truck or delivery lanes,will require a thicker section and should be designed
using a paving section consisting of 4 inches of Class ''/:-inch HMA asphalt above 2 inches of
Crushed Surfacing Top Course (CSTC) meeting criteria set forth in the WSDOT Standard
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Specification 9-03.9(3), overlying gravel base. The base material for the road section should
consist of"gravel base"which may include 10 inches of gravel borrow (with 100% passing the 2-
inch sieve) or 8 inches of Crushed Surfacing Base Course (CSBC) as classified by WSDOT 9-03.9(3)
Standards and Specifications.
Concrete Pavement Sections
Concrete pavements could be used for skate park surface, access drives and parking areas at the
project site. Design of concrete pavements is a function of concrete strength, reinforcement
steel, and the anticipated loading conditions for the roads. GeoTest expects that concrete
pavement sections, if utilized, will be at least 4 inches thick and be founded on a minimum of 8
inches of compacted gravel base. For design purposes, a vertical modulus of subgrade reaction
of 200 pounds per cubic inch (pci) should be expected for concrete elements constructed over
properly placed and compacted Import Structural Fill.The design of concrete access and parking
areas will need to be performed by a structural engineer. GeoTest recommends that subgrade
soils supporting concrete pavement sections include minor grade changes to allow for passive
drainage away from the pavement.
GeoTest is available to further consult, review and/or modify our pavement section
recommendations based on further discussion and/or analysis with the project team/owner.The
above pavement sections are initial recommendations and may be accepted and/or modified by
the site civil engineer based on the actual finished site grading elevations and/or the owner's
preferences.
Stormwater Infiltration Potential
The undisturbed native soils underlying the subject site generally consist of clay and have a high
fines content (typically 77 to 93 percent passing the#200 sieve). The native soils will restrict the
conventional infiltration of stormwater into the soil and, in or opinion, supports the presence of
a "hydraulic restriction layer" as defined by the Stormwater Management Manual of Western
Washington (2014).This is the stormwater document currently enacted by the City of Anacortes.
Zones of perched groundwater seepage may be encountered depending on the time of year or
following an extended period of heavy precipitation.
It is our opinion that Pilot Infiltration Testing, as detailed within the Optional Services section of
our original service agreement, should not be performed at the project site. We expect that
stormwater management will be accomplished via engineered design or directed towards a
municipally approved discharge location.
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Geotechnical Consultation and Construction Monitoring
GeoTest recommends that we be involved in the project design review process. The purpose of
the review is to verify that the recommendations presented in this report are understood and
incorporated in the design and specifications.
We also recommend that geotechnical construction monitoring services be provided. These
services should include observation by GeoTest personnel during structural fill placement,
compaction activities and subgrade preparation operations to confirm that design subgrade
conditions are obtained beneath the areas of improvement.
Periodic field density testing should be performed to verify that the appropriate degree of
compaction is obtained. The purpose of these services is to observe compliance with the design
concepts, specifications, and recommendations of this report. In the event that subsurface
conditions differ from those anticipated before the start of construction, GeoTest Services would
be pleased to provide revised recommendations appropriate to the conditions revealed during
construction.
GeoTest is available to provide a full range of materials testing and special inspection during
construction as required by the local building department and the International Building Code.
This may include specific construction inspections on materials such as reinforced concrete,
reinforced masonry,wood framing and structural steel.These services are supported by our fully
accredited materials testing laboratory.
USE OF THIS REPORT
GeoTest Services has prepared this report for the exclusive use of Grindline Skateparks and their
design consultants for specific application of the proposed Anacortes Skate Park redevelopment
to be located in Anacortes,Washington. Use of this report by others is at the user's sole risk.This
report is not applicable to other site locations. Our services are conducted in accordance with
accepted practices of the geotechnical engineering profession; no other warranty, express or
implied, is made as to the professional advice included in this report.
Our site explorations indicate subsurface conditions at the dates and locations indicated. It is not
warranted that these conditions are representative of conditions at other locations and times.
The analyses, conclusions, and recommendations contained in this report are based on site
conditions to the limited depth and time of our explorations, a geological reconnaissance of the
area, and a review of previously published geological information for the site. If variations in
subsurface conditions are encountered during construction that differ from those contained
within this report, GeoTest should be allowed to review the recommendations and, if necessary,
make revisions. If there is a substantial lapse of time between submission of this report and the
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start of construction,or if conditions change due to construction operations at or adjacent to the
project site, we recommend that we review this report to determine the applicability of the
conclusions and recommendations contained herein.
The earthwork contractor is responsible to perform all work in conformance with all applicable
WISHA/OSHA regulations. GeoTest Services, Inc, is not responsible for job site safety on this
project, and this responsibility is specifically disclaimed.
Attachments: Figure 1 Vicinity Map
Figure 2 Site and Exploration Plan
Figure 3 Conceptual Footing &Wall Drain Section
Figure 4 Soil Classification System and Key
Figures 5-9 Boring Logs
Figures 10 Laboratory Testing Results
Attached Report Limitations and Guidelines (4 Pages)
19
GeoTest Services, Inc. March 30, 2022
Anacortes Skate Park—Anacortes,Washington Project Number: 22-0278
REFERENCES
American Society of Civil Engineers (ASCE). 2017. Minimum Design Loads and Associated Criteria for Buildings and Other
Structures.ASCE/SEI 7-16.
American Society for Testing and Materials (ASTM). (2012). ASTM D1557-12e1, Standard Test Methods for Laboratory
Compaction Characteristics of Soil Using Modified Effort,
American Society for Testing and Materials(ASTM).Standard Practice for Classification of Soils for Engineering Purposes
(Unified Soil Classification System).ASTM D2487—17e1.
American Society for Testing and Materials(ASTM).Standard Practice for Description and Identification of Soils(Visual-Manual
Procedures).ASTM D2488—17e1.
American Society for Testing and Materials (ASTM). (2017). ASTM D6938, Standard Methods for In-Place Density and Water
Content of Soil and Soil-Aggregate by Nuclear Methods.
Atwater,B.F.and Haley,E.H.,(1997)Recurrence Intervals for Great Earthquakes of the Post3,500 Years at Northeastern Willapa
Bay, Washington.USGS Survey Professional Paper 1576.
Barrie,J.V.,Greene,H.G.,(2017).The Devil Mountain Fault Zone:An active Cascadia upper plate zone of deformation,Pacific
Northwest of North America(pp.228-241)(Sedimentary Geology,Volume 364).
City of Anacortes Municipal Code—Geologically Hazardous Areas§§19.70(2021).
Gariepy,D.,Graul,C.Heye,A.,Howie,D,Labib,F.&Song,K.(n.d.)2019.Stormwater Management Manual for Western
Washington(2019 SMMWW)(pp.1-1108)(United States,Washington Department of Ecology).
Google Earth ProT"(n.d.)Retrieved March 2022 from https://www.google.com/earth/.
International Building Code(IBC),2018,International Code Council.
Palmer et al.,2004.Liquefaction Susceptibility and Site Class Maps of Washington State by County.1:24,000.Washington
Division of Geology and Earth Resources,Open File Report 2004-20.
USDA Web Soil Survey.Retrieved March 2022 from https://websoilsurvey.sc.egov.usda.gov/App/WebSoilSu"ey.aspx.
Washington Administrative Code(WAC).(2020). WAC296-155-6640,Retrieved March 2022,from
https://app.leg,wa.gov/wac/default.aspx?cite=296-155-66403.
Washington Geologic Information Portal,Washington State Department of Natural Resources—Online Web Services,Retrieved
March 2022 from https://geologyportal.dnr.wa.gov.
Washington State Department of Ecology. Well Log Viewer. Retrieved March 2022 from
https:Happswr.ecology.wa.gov/weliconstruction/map/WCLSWebMap/.
Washington State Department of Transportation/America)Public Works Association Washington State Chapter.2020.Standard
Specifications for Road,Bridge,and Municipal Construction M 41-10.
Washington Lidar Portal. (n.d.).Retrieved March 2022 from http://Iidarportal.dnr.wa.gov/.
20
A/ Map Referenced from DNR LIDAR Portal
N PROJECT LOCATION
1 Mile
Anacortes
Crpnhprry
!nke Park
AM
Andeovo,
Anacar[es
11 � ' Refinery
10 S
and t
RYA 20 SPUR =
r la s • Ano�ortes _—_ sound
community-1 _-- y Refiner,.
Forest Lands
• — 1
•
I
f
Fidolgo
Island
Date:3-1-22 By: HS Scale: As Shown Project
VICINITY MAP 22-0278
�T ANACORTES SKATE PARK REVISION Figure
R AVENUE—PARCEL NO. PJ7984
ANACORTES,WASHINGTON 98221
r
} ` t51
• E r .
T`
f f
B-5
B-4
t
� l
B-3
B-2
'r
eB-# =Approximate Boring Location Image Referenced from Google Earth
Date:3-17-22 By: DM Scale:As Shown Project
T SITE AND EXPLORATION PLAN 22-0278
(ec R AVENUE
TES SKATE PARK REVISION Figure
AVENUE—PARCEL NO. P77984
ANACORTESr WASHINGTON 98221
CONCEPTUAL FOOTINGS WITH INTERIOR SLAB-ON-GRADE
+ + F Typical Framing
Compacted Low-Permeability Soil
(12 inch minimum) ` `
Floor Slab
or Pavement , , , _
(2 inch minimum) , ; ; .'.'.'.'.,.'.,.,.;.;.; ; '.
Vapor Burner
Slope to drain away
from structure. _ — - �� ',',', 1J1J:f~J4J1J1J1J1J:f:l1J1J1J11!J:J:J:JLJ1J1J:J:J1J~J~JLJ1J1�
1J:J:2:JyJ~�'1JLr1ryl:l:1~f1f1f'JiJ�JiJiJ~J:J1JiJiJ�J~J~J:J1�
r
/ + +•+ '%'�"'."!:i�`� - Coarse Gravel Capillary Break
Pinch minimum,typically clear crushed)
Suitable Sail
• R•, , Free Draining Sand
`t , and Gravel Fill
Approved Non-woven , , ,
Geotextile Filter Fabric -------
(18 inch minimum fabric lap)
Suitable Sail
Drainage Material
(Drain Rock or Clear
Crushed Rock w/no fines) Appropriate Waterproofing
Applied to Exterior of Wall
Four Inch Diameter,Perforated,Rigid PVC Pipe
(Perforations oriented down,wrapped in non woven
geotextile filter fabric,directed to suitable discharge)
Notes:
Footings should be properly buried for frost protection in accordance with International Building
Code or local building codes (Typically 18 inches below exterior finished grades).
This figure is not intended to be representative of a design.This figure is intended to present
concepts that can be incorporated into a functional foundation drain designed by a Civil Engineer.
In all cases, refer to the Civil plan sheet for drain details and elevations.
Date:3-1-22 By: DM Scale: None Project
CONCEPTUAL FOOTING &WALL DRAIN SECTION 22-0278
�T TES SKATE PARK REVISION Figure
R AVENUE PARCEL NO.P77984
ANACORTES,WASHINGTON 98221
Soil Classification System
uscs
MAJOR GRAPHIC LETTER TYPICAL
DIVISIONS SYMBOL SYMBOL DESCRIPTIONS"'(()
GRAVEL AND CLEAN GRAVEL °o 0 o° GW Well-graded gravel;gravel/sand mixlure(s);little or no fines
GRAVELLY SOIL (Little or no fines) o 0000
—O.�N o -o GP Poorly graded gravel;graveVsand mixture(s);little or no foes
Nsm (More than 50%of
m'm coarse fraction retained GRAVEL WITH FINES GM Silty gravel;gravel/sand/silt mixtures)
ZF. on No.4 sieve) (Appreciable amount of
Q o N foes) GC Clayey gravel;gravel/sand/day mixture(s)
Q n CLEAN SAND Sw Well-graded sand;gravelly sand;little or no fines
S= SANDY SOIL SANDAND
(Little or no fines)
Qo - SP Poorly graded sand;gravelly sand;little or no fines
O (More than 50%ofTW U v— coarsefraction passed SAND WITH FINES SM Silty sand;sand/silt mlMure(s)
through No.4 sieve) (Appreciable amount of
fines) wv SC Clayey sand;sand/day mixture(s)
Inorganic silt and very fine sand;rock Flour;silty or clayey fine
Jew SILT AND CLAY ML sand or dayey silt with slight plasticity
O m o Inorganic day of low to medium plasticity;gravelly day;sandy
NO E N (Liquid limit less than 50) C'L day;silty day;lean Gay
W o d_
3OL Organic sill;organic,silty day of low plasticity
ZoZ
-ram MH Inorganic silt;micaceous or diatomaceous fine sand
O . SILT AND CLAY
W @ m CH Inorganic day of high plasticity;fat day
LL E (Liquid limit greater than 50)
- OH Organic day of medium to high plasticity;organic silt
HIGHLY ORGANIC SOIL PT Peak humus;swamp soil with high organic content
GRAPHIC LETTER
OTHER MATERIALS SYMBOL SYMBOL TYPICAL DESCRIPTIONS
PAVEMENT AC or PC Asphalt concrete pavement or Portland cement pavement
ROCK RK Rock(See Rock Classification)
WOOD WD Wood,lumber,wood chips
DEBRIS O DB Construction debris,garbage
Notes: 1. Sol descriptions are hosed on the general approach presented in the Standard Practice for Description and IdentiHcallon o/Soils(Visual-Manual Procedure),
as outlined in ASTM D 2488,Where laboratory index testing has been conducted,sail classifications are based an the Standard Test Method for Classification
of Soils for Engineering Purposes,as outlined in ASTM D 2487.
2. Sol description terminology is based on visual estimates(in the absence of laboratory test data)of the percentages of each soil type and is defined as follows:
Primary Constituent: >50%-"GRAVEL,""SAND,""SILT,""CLAY,"etc
Secondary Constituents: >30%and<50%-"very gravelly,"'Very sandy,""very silty,"etc.
>12%and 7 30%-"gravelly,""sandy,""silty,"etc.
Additional Constituents: > 5%and 712%-"slightly gravelly,"'slightly sandy,""slightly silty,"etc.
< 5%-"trace gravel,""trace sand,""trace silt,"etc,or not noted.
Drilling and Sampling Key Field and Lab Test Data
SAMPLE NUMBER&INTERVAL SAMPLER TYPE
Cade Description Code Description
Sample Identification Number a 3.25-inch O.D.,242-inch I.D.Split Spoon PP=1.0 Packet Penetrometer,tsf
b 2.00-Inch O.D.,1.50-inch I.D.Split Spoon TV=0.6 Towers,tsf
Recovery Depth Interval c Shelby Tube PID=100 Photdonization Detector VOC screening,ppm
1� J~ Sample Depth Interval d Grab Sample W=10 Moisture Content,%
e Other-See text if applicable D=120 Dry Density,pd
Portion of Sample Retained 1 3004b Hammer,30-inch Drop -200=60 Material smaller than No.200 sieve,%
for Archive or Analysis 2 140-Ib Hammer,30-inch Drop GS Grain Size-See separate figure for data
3 Pushed AL Atterherg Limits-See separate figure for data
4 Other-See text if applicable GT Other Geatechnical Testing
Groundwater CA Chemical Analysis
4 Approximate water elevation at time of drilling(ATD)or an dale noted. Groundwater
A7D levels can fluctuate due to precipitation,seasonal conditions,and other factors.
7T An -Ps Skate Park Figure
R Avenueue-Parcel No. P77984 Soil Classification System and Key A
Anacortes, WA 4
B-1
SAMPLE DATA SOIL PROFILE GROUNDWATER
w M Drilling Method'Hollow-stem Auer
z o :9 �^' E Ground Elevation(ft).undetermined
a E E 3 �+ Drilled By Bortecl Inc /DM
o w
❑ N CZS N ai F V
0 SM Loose,dark brown,wet,very silty SAND
(Topsoll/FlII)
Groundwater not encountered.
CL Very suff,gray to brown,moist,gravelly
CLAY(Glaclomarine Drift)-moderate
mottling observed
2
1 b2 17
4
-Grading to gray with no mottling and
an increase in density
21 b2 24 W-21
6 GS
-Trace wood debris observed
8
31 b2 20
10
4 b2 16
2
Grading to medium stiff and light gray
51 b2 12W=28 -Pocket Penetrometer=1.75 tsf
5 62 12 CIS
AL
14
Boring Completed 03/07/22
Total Depth of Boring=14D It.
Notes: 1. Stratigraphic contacts are based on field interpretations and are approximate,
2. Reference to the text of this report is necessary for a proper understanding of subsurfaceconditions.
3. Refer to"Soil Classification System and Key"figure for explanation of graphics and symbols.
409T An -Ps Skate Park Figure
R Avenueue-Parcel No. P77984 Log of Boring B-1
Anacortes,WA
iI
till
B-2
SAMPLE DATA SOIL PROFILE GROUNDWATER
.p10 v M Drilling Method,Hollow-stem Auger
E E n°
,. z' > LL°o ;? Ground Elevation(ft)•Undetermined
w `v N H
n E c E a u Drilled By Bortecl Inc /DM
vial vi m F 0
0 SM Loose,dark brown,wet,gravelly,very
silty SAN0(Topsoil/Fill)
Groundwater not encountered.
2
CL Very stiff,Ilghtgray,damp,slightlysandy
CLAY(Glaciomanne Drift)-scattered
6 b2 IS W=24 mottling observed
GS
4
Grading to medium gray with decrease
In mottling
71 b2 26
6
-Grading to moist with decrease in sand
8 -Pocket Penetrometer=3.0 tsf
81 b2 18
10 -Trace gravel observed
91 b2 18
2
101 b2 12Grading to grayish brown and stiff
10 62 12
14
Boring Completed 03/07/22
Total Depth of Boring=14.0 ft.
Notes: 1. Stratigraphic contacts are based on field interpretations and are approximate.
2. Reference to the text of this report is necessary for a proper understanding of subsurface conditions.
3. Referto'Soil Classification System and Key"figure for explanation of graphics and symbols.
007 An -Ps Skate Park Figure
T RAvenue Avenue-Parcel No. P77984 Log of Boring B-2 G+
Anacortes, WA V
B-3
SAMPLE DATA SOIL PROFILE GROUNDWATER
Drilling Method Hollow-stem Auger
E > E a
LL T Ground Elevation(ftUndetermined
L d y Q v�i (J E N
a E c E 3 ,a U Drilled By' Borteci Inc /DM
o moil � m Iv l7 7 j
0 SM Loose,dark brown,wet,slightly gravelly,
very silty SAND(Topsoil/Fill)
Groundwater not encountered.
2 CL very stiff,gray to rown,damp,sandy
CLAY with trace gravel(Glaciomarine
Drift)-moderate mottling observed
ill b2 20
4 -Auger shuttering at 4 feet BGS
-Grades to gray,slightly gravelly,slightly
sandy with strong mottling
12 62 21
6
-Grading to sandy at 7.5 feet BGS
B W=20
13 b2 20 GS
10
14 b2 19
12
151 62 14
14
Boring Completed 03/07/22
Total Depth of Boring=14.0 ft.
Notes: 1. Stratigraphic contacts are based on field Interpretations and are approximate.
2. Reference to the text of this report is necessary for a proper understanding of subsurface conditions.
3. Refer to"Soil Classification System and Key'figure for explanation of graphics and symbols.
C �T An - Ps Skate Park Figure
RAvenue uearcel No. P77984 Log of Boring B-3 7
Anacortes, WA /
I
B-4
SAMPLE DATA SOIL PROFILE GROUNDWATER
o. a o Drilling Method Hollow-stem Auger
E a
0 `u E Ground Elevation(ft)•Undetermined
$
n E E a E E o N Drilled By Bortecl Inc./DM
yr o7S vi ai la
0 SM Loose,dark brown,wet,slightly
g y gravelly,
very silty SAND(Topsail)
Groundwater not encountered.
CL Medium stiff,gray to brown,moist,
slightly sandy,gravelly CLAY
(Glaciomarine Drift)-minor organic
debris observed
2
16 b2 8
4
Grades to very stiff,gray and damp at S
feet BGS
171 b2 25
6
-Decease in mottling
8
181 62 15
10 -Grading to stiff at 10 feet BGS
191 b2 13
12
20 62 9
14
Boring Completed 03/07/22
Total Depth of Boring'-14.0 ft.
Notes: 1. Stratigraphid contacts are based on field Interpretations and are approximate.
2. Reference to the text of this report is necessary for a proper understanding of subsurface conditions.
3. Refer to"Sol]Classification System and Key"figure for explanation of graphics and symbols.
�T n - Rs Skate Park Figure
RAvenue uearcel No. P77984 Log of Boring B-4
Anacortes, WA
B-5
SAMPLE DATA SOIL PROFILE GROUNDWATER
n E o Drilling Method,Hallow-stem Auger
z' °o E Ground Elevation(ft) Undetermined
w v N m u N
n c E at4u. Drilled By Bortecl Inc./DM
v
v�o7J vt0i m F l7
0 SM loose,dark brown,wet,gravelly,very
Silty SAND(Topsoil/Fill)
Groundwater not encountered.
2 CL Very stiff,gray to brown,slightly gravelly,
slightly sandy CLAY(Giaciomarine Drift)
21 b2 16
4
-Grades to gray at 5 feet BGS
221 b2 19
6
8
23 b2 18
10 -Grading to stiff
241 b2 13 W=28
GS
12
251 62 it
14
Boring Completed 03/07/22
Total Depth of Boring=14.0 ft.
Notes: 1. Stratigraphic contacts are based on field interpretations and are approximate.
2. Reference to the text of this report is necessary for a proper understanding of subsurface conditions.
3. Referto"Sall Classification System and Key"figure for explanation of graphics and symbols.
T Anacortes Skate Park Figure
R Avenue- Parcel No. P77984 Log of Boring B-5 (�
Anacortes, WA 9
U.S.SIEVE OPENING IN INCHES E U.S.SIEVE NUMBERS HYDROMETER
6 4 3 2 1.5 1 3/4 1/2 3A. 6 610 1416 20 30 40 50 60 100 140 200
100
90
80
70R 4-
L
3 60
T
a
50
LL
C
N
U
a 40
30
20
10
D
100 10 1 0.1 0.01 0.001
Grain Size in Millimeters
Cobbles Gravel Sand Silt or Clay
coarse fine coarse I medium fine
Point Depth Classification LL PL PI C� Cu
• B-1 5.0 Sandy CLAY With trace gravel (CL)
* B-1 12.5 Slightly sandy CLAY (CL) 49 21 28
B-2 2.5 Slightly sandy CLAY (CL)
* B-3 7.5 Sandy CLAY vdth trace gravel (CL)
O B-5 10.0 Slightly sandy CLAY (CL)
Point Depth D D D D D %Coarse %Fine Coarse %Medium %Fine %Floes
p 50 so 50 30 0 Gravel Gavel Sand Sand Sand
0 B-1 5:0 0.289 0.0 3.2 1.4 3.5 11.5 80.3
m B-1 12.5 0.0 0.0 0.3 1.2 5.0 93.5
♦ B-2 2.5 0.098 0.0 0.5 0.4 3.1 7.3 88.8
* B-3 7.5 0.32 0.0 1.7 1.5 4.9 14.7 77.1
O B-5 10.0 0.0 0.2 0.2 0.7 5.5 93.4
C�= D3o2/(D6n" Diu) To be well graded: 1 < C,<3 and
Cu= D6dD1c C,>4 for GW or C > 6 for SW
10 7T An -Ps Skate Park Figure
R Avenueue Parcel No. P77984 Grain Size Test Data 10
Anacortes, WA
REPORT LIMITATIONS AND GUIDELINES FOR ITS USE'
Subsurface issues may cause construction delays, cost overruns, claims, and disputes. While you
cannot eliminate all such risks, you can manage them. The following information is provided to
help:
Geotechnical Services are Performed for Specific Purposes, Persons,and Projects
At GeoTest our geotechnical engineers and geologists structure their services to meet specific
needs of our clients. A geotechnical engineering study conducted for a civil engineer may not
fulfill the needs of an owner, a construction contractor or even another civil engineer. Because
each geotechnical engineering study is unique, each geotechnical engineering report is unique,
prepared solely for the client. No one except you should rely on your geotechnical engineer who
prepared it. And no one — not even you — should apply the report for any purpose or project
except the one originally contemplated.
Read the Full Report
Serious problems have occurred because those relying on a geotechnical engineering report did
not read it all. Do not rely on an executive summary. Do not read selected elements only.
A Geotechnical Engineering Report is Based on a Unique Set of Project-Specific Factors
GeoTest's geotechnical engineers consider a number of unique, project-specific factors when
establishing the scope of a study. Typical factors include: the clients goals, objectives, and risk
management preferences; the general nature of the structure involved its size, and
configuration; the location of the structure on the site; and other planned or existing site
improvements, such as access roads, parking lots, and underground utilities. Unless GeoTest,
who conducted the study specifically states otherwise, do not rely on a geotechnical engineering
report that was:
• not prepared for you,
• not prepared for your project,
• not prepared for the specific site explored, or
• completed before important project changes were made.
1
Sinformation in this document is based upon material developed by ASFE,Professional Firms Practicing in the Geosciences(asfe.org)
Typical changes that can erode the reliability of an existing geotechnical engineering report
include those that affect:
• the function of the proposed structure, as when it's changed,for example,from a parking
garage to an office building, or from a light industrial plant to a refrigerated warehouse,
• elevation, configuration, location, orientation, or weight of the proposed construction,
• alterations in drainage designs; or
• composition of the design team; the passage of time; man-made alterations and
construction whether on or adjacent to the site;or by natural alterations and events,such
as floods, earthquakes or groundwater fluctuations; or project ownership.
Always inform GeoTest's geotechnical engineer of project changes — even minor ones — and
request an assessment of their impact. Geotechnical engineers cannot accept responsibility or
liability for problems that occur because their reports do not consider developments of which
they were not informed.
Subsurface Conditions Can Change
This geotechnical or geologic report is based on conditions that existed at the time the study was
performed. Do not rely on the findings and conclusions of this report,whose adequacy may have
been affected by:the passage of time; by man-made events,such as construction on or adjacent
to the site;or by natural events,such as floods,earthquakes,or groundwater fluctuations.Always
contact GeoTest before applying the report to determine if it is still relevant. A minor amount of
additional testing or analysis will help determine if the report remains applicable.
Most Geotechnical and Geologic Findings are Professional Opinions
Our site exploration identifies subsurface conditions only at those points where subsurface tests
are conducted or samples are taken. GeoTest's engineers and geologists review field and
laboratory data and then apply their professional judgment to render an opinion about
subsurface conditions throughout the site. Actual subsurface conditions may differ—sometimes
significantly—from those indicated in your report. Retaining GeoTest who developed this report
to provide construction observation is the most effective method of managing the risks
associated with anticipated or unanticipated conditions.
2
1lnformation in this document is based upon material developed by ASFE,Professional Firms Practicing in the Geosciences(asfe.org)
A Report's Recommendations are Not Final
Do not over-rely on the construction recommendations included in this report. Those
recommendations are not final, because geotechnical engineers or geologists develop them
principally from judgment and opinion. GeoTest's geotechnical engineers or geologists can
finalize their recommendations only by observing actual subsurface conditions revealed during
construction. GeoTest cannot assume responsibility or liabilityforthe report's recommendations
if our firm does not perform the construction observation.
A Geotechnical Engineering or Geologic Report may be Subject to Misinterpretation
Misinterpretation of this report by other design team members can result in costly problems.
Lower that risk by having GeoTest confer with appropriate members of the design team after
submitting the report. Also, we suggest retaining GeoTest to review pertinent elements of the
design teams plans and specifications. Contractors can also misinterpret a geotechnical
engineering report. Reduce that risk by having GeoTest participate in pre-bid and
preconstruction conferences, and by providing construction observation.
Do not Redraw the Exploration Logs
Our geotechnical engineers and geologists prepare final boring and testing logs based upon their
interpretation of field logs and laboratory data. To prevent errors of omissions,the logs included
in this report should never be redrawn for inclusion in architectural or other design drawings.
Only photographic or electronic reproduction is acceptable; but recognizes that separating logs
from the report can elevate risk.
Give Contractors a Complete Report and Guidance
Some owners and design professionals mistakenly believe they can make contractors liable for
unanticipated subsurface conditions by limiting what they provide for bid preparation. To help
prevent costly problems, give contractors the complete geotechnical engineering report, but
preface it with a clearly written letter of transmittal. In that letter, consider advising the
contractors that the report was not prepared for purposes of bid development and that the
report's accuracy is limited; encourage them to confer with GeoTest and/or to conduct additional
study to obtain the specific types of information they need or prefer. A pre-bid conference can
also be valuable. Be sure contractors have sufficient time to perform additional study. Only then
might you be in a position to give contractors the best information available,while requiring them
to at least share some of the financial responsibilities stemming from unanticipated conditions.
3
Slnformation in this document Is based upon material developed by ASFE,Professional Firms Practicing in the Geosclences(asfe.org)
l�II1�R
In addition, it is recommended that a contingency for unanticipated conditions be included in
your project budget and schedule.
Read Responsibility Provisions Closely
Some clients, design professionals, and contractors do not recognize that geotechnical
engineering or geology is far less exact than other engineering disciplines. This lack of
understanding can create unrealistic expectations that can lead to disappointments, claims, and
disputes. To help reduce risk, GeoTest includes an explanatory limitations section in our reports.
Read these provisions closely. Ask questions and we encourage our clients or their
representative to contact our office if you are unclear as to how these provisions apply to your
project.
Environmental Concerns Are Not Covered in this Geotechnical or Geologic Report
The equipment, techniques, and personnel used to perform an environmental study differ
significantly from those used to perform a geotechnical or geologic study. For that reason, a
geotechnical engineering or geologic report does not usually relate any environmental findings,
conclusions, or recommendations; e.g., about the likelihood of encountering underground
storage tanks or regulated containments, etc. If you have not yet obtained your own
environmental information,ask your geotechnical consultant for risk management guidance. Do
not rely on environmental report prepared for some one else.
Obtain Professional Assistance to Deal with Biological Pollutants
Diverse strategies can be applied during building design, construction, operation, and
maintenance to prevent significant amounts biological pollutants from growing on indoor
surfaces. Biological pollutants includes but is not limited to molds, fungi, spores, bacteria and
viruses. To be effective, all such strategies should be devised for the express purpose of
prevention, integrated into a comprehensive plan, and executed with diligent oversight by a
professional biological pollutant prevention consultant. Because just a small amount of water or
moisture can lead to the development of severe biological infestations, a number of prevention
strategies focus on keeping building surfaces dry. While groundwater, water infiltration, and
similar issues may have been addressed as part of this study, the geotechnical engineer or
geologist in charge of this project is not a biological pollutant prevention consultant; none of the
services preformed in connection with this geotechnical engineering or geological study were
designed or conducted for the purpose of preventing biological infestations.
4
Slnformation in this document Is based upon material developed by ASFE,Professional Firms Practicing in the Geosciences(asfe.org)
APPENDIX 3— Model Soil Management Plan for BMP T5.13
An alternate document acceptable to the City of Anacortes is a Test Report provided by the Soils Supplier that
identifies the soils to be used meet the specifications outlined under Minimum Requirement 5. The
specifications are in both WSDOT and CSI Formats. For specifications, refer to the above referenced PDF.
This submittal can be a deferred submittal since most projects are not sure who the supplier will be at the time
of building permit application. For projects that trigger Minimum Requirements 1 through 5, the Test Report will
be provided to the Building Department. Projects triggering Minimum Requirements 1 through 9, the Test
Report will be provided to the Engineering Department.
Version Date: August 30, 2022
DEFERRED SUBMITTAL: PROVIDE A TEST REPORT FROM SOILS SUPPLIER TO THE BUILDING DEPT.
PROJECT INFORMATION "Model Soil Management Plan for BMP T5.13" age#_ofpages
Com lete all information on page 1;only site address and permit number on additional pa es.
Site Address/Lot No.:
Permit Type: Permit Number:
Permit Holder: Phone:
Mailing Address:
Contact Person: Phone:
Plan Prepared By:
ATTACHMENTS REQUIRED Check off required items that are attached to thisplan)
_Site Plan showing,to scale: _Areas of undisturbed native vegetation(no amendment required)
_New planting beds and turf areas(amendment required)
Type of soil improvement proposed for each area
Soil test results re uired if proposing custom amendment rates
Product test results for proposed amendments
AREA# (should match Area#on Site Plan)
PLANTING TYPE —Turf —Undisturbed native vegetation
_Planting Beds _Other:
SQUARE FOOTAGE OF THIS AREA: square feet
SCARIFICATION _inches(depth)of scarification needed to achieve finished total 12"loosened depth.
_Subsoil will be scarified
PRE-APPROVED _inches of compost or imported topsoil applied
A MENDMENT METHOD: X 3 1(conversion factor, inches to cubic yards) PRODUCT:
_Topsoil import =cu.yards per 1,000 sq.ft.
—Amend with compost X _,000s sq.ft.in this area
_Stockpile and amend _ =cubic yards of amendment QUANTITY: CU.YDS,
cu.yds.stockpiled) (needed to cover this area to designated depth)
CUSTOM AMENDMENT Attach test results and calculations.
—Topsoil import inches organic matter or topsoil import PRODUCT:
—Topsoil&compost lift X 3_1
_Amend =cu.yards 11,000 sq.ft.
_Stockpile and amend X _,000s sq.ft.in this area
cu.yds.stockpiled) _ =cubic yards of amendment .... QUANTITY: CU.YDS.
MULCH _,000 sq.ft. PRODUCT:
X 6_2 (conversion, to give 2 inch mulch depth)
=cubic yards of mulch QUANTITY: CU.YDS.
TOTAL AMENDMENT/TOPSOTUMULCH FOR ALL AREAS(complete on page I only, totalin all areas/pages in this Plan)
❑ Product#1: ❑Quantity: cu.yds.
❑ Test Results: %organic matter C:N ratio<25:1 (except mulch,or<35:1 for native plants) "stable" es/no)
❑ Product#2: ❑ Quantity: cu.yds.
❑ Test Results: %organic matter C:N ratio<25:1 (except mulch,or<35:1 for nativeplants) "stable"(yes/no)
❑ Product#3: ❑ Quantity: cu.yds.
❑ Test Results: %organic matter C:N ratio<25:1 (except mulch,or<35:1 for nativeplants) "stable" es/no
Date: Inspector: Approved: Revisions Required:
Date: Inspector: Approved: Revisions Required:
Version Date: August 30, 2022
APPENDIX 4— Determining Construction Site Sediment Damage Potential (Appendix 7— NPDES Phase
II Permit)
Note: See attached. All projects within the City of Anacortes are required to complete that document under
Appendix 4.
Version Date: August 30, 2022
Western Washington Phase Il5tormwater Permit
i. APPENDIX 7 — Determining Construction Site
Sediment Damage Potential
The following rating system allows objective evaluation of a particular development site's potential to
discharge sediment. Permittees may use the rating system below or develop alternative process
designed to identify site-specific features which indicate that the site must be inspected prior to clearing
and construction. Any alternative evaluation process must be documented and provide for equivalent
environmental review.
Step one is to determine if there is a sediment/erosion sensitive feature downstream of the development
site. If there is such a site downstream complete step two, assessment of hydraulic nearness. If there is
a sediment/erosion sensitive feature and it is hydraulically near the site then go to step three to
determine the construction site sediment transport potential.
ii. STEP 1 —Sediment/Erosion Sensitive Feature Identification
Sediment/erosion sensitive features are areas subject to significant degradation due to the effect of
sediment deposition or erosion. Special protection must be provided to protect them.
Sediment/erosion sensitive features include but are not limited to:
i. Salmonid bearing fresh water streams and their tributaries or freshwater streams that
would be Salmonid bearing if not for anthropogenic barriers;
ii. Lakes;
iii. Category I, II, and III wetlands;
v® marine near-shore habitat;
V. Sites containing contaminated soils where erosion could cause dispersal of
contaminants; and
vi. Steep slopes (25% or greater) associated with one of the above features.
Identify any sediment/erosion sensitive features, and proceed to step two. If there are none the assessment
is complete.
STEP 2—Hydraulic Nearness Assessment
Sites are hydraulically near a feature if the pollutant load and peak quantity of runoff from the site will not
be naturally attenuated before entering the feature. The conditions that render a site hydraulically near
to a feature include, but are not limited to, the following:
i. The feature or a buffer to protect the feature is within 200 feet downstream of the site.
ii. Runoff from the site is tight-lined to the feature or flows to the feature through a channel
or ditch.
August 1, 2013, Modified January 16, 2015 Appendix 7- Determining Sediment Damage
Potential Page 1 of 3
Version Date: August 30, 2022
A site is not hydraulically near a feature if one of the following takes place to provide attenuation
before runoff from the site enters the feature:
iv. Sheet flow through a vegetated area with dense ground cover
V. Flow through a wetland not included as a sensitive feature
vi. Flow through a significant shallow or adverse slope, not in a conveyance
channel, between the site and the sensitive feature.
Identify any of the sediment/erosion sensitive features from step one that are hydraulically near
the site, and proceed to step three. If none of the sediment/erosion sensitive features are
hydraulically near the site, the assessment is complete.
vii. STEP 3—Construction Site Sediment Transport Potential
Using the worksheet below, determine the total points for each development site. Assign points
based on the most critical condition that affects 10% or more of the site.
If soil testing has been performed on site, the results should be used to determine the
predominant soil type on the site. Otherwise, soil information should be obtained from the
county soil survey to determine Hydrologic Soil Group(Table of Engineering Index Properties
for step 1.D) and Erosion Potential (Table of Water Features for step 1.E)
When using the county soil survey, the dominant soil type may be in question, particularly when
the site falls on a boundary between two soil types or when one of two soil types may be present
on a site. In this case, the soil type resulting in the most points on the rating system will be
assumed unless site soil tests indicate that another soil type dominates the site.
Use the point score from Step 3 to determine whether the development site has a high potential
for sediment transport off of the site.
Total Score Transport Rating
<100 Low
11100 High
A high transport rating indicates a higher risk that the site will generate sediment contaminated
runoff.
Construction Site Sediment Transport Potential Worksheet
A. Existing slope of site (average weighted by aerial extent): Points
2% or less 0
>2-5% ..............................................................................................5
>5-10% ..........................................................................................15
>10-15% ........................................................................................30
>15% .............................................................................................50
B. Site Area to be cleared and/or graded:
<5,000 sq. ft ...................................................................................0
5,000 sq. ft.— 1 acre.................................................................... 30
>1 acres.......................................................................................50
C. Quantity of cut and/or fill on site:
<500 cubic yards............................................................................0
500—5,000 cubic yards .................................................................3
>5,000— 10,000 cubic yards.........................................................10
>10,000—20,000 cubic yards.......................................................25
>20,000 cubic yards.....................................................................40
D. Runoff potential of predominant soils (Natural Resources Conservation Service): Hydrologic
soilgroup A....................................................................................0
Hydrologic soil group B.................................................................®
Hydrologic soil group C.................................................................20
Hydrologicsoil group D.................................................................40
E. Erosion Potential of predominant soils (Unified Classification System): GW, GP,SW,
SPsoils..........................................................................................0
Dual classifications (GW-GM, GP-GM, GW-GC,
GP-GC, SW-SM, SW-SC, SP-SM, SP-SC)..........................10
GM, GC, SM, SC soils.................................................................J 0
ML, CL, MH, CH soils...................................................................40
F. Surface or Groundwater entering site identified and intercepted):
Yes........................................................
........................................
®
No................................................................................................25
G. Depth of cut or height of fill >10 feet:
Yes...............................................................................................25
No..............................................................................—.........................0
H. Clearing and grading will occur in the wet season (October 1 — May 1): Yes 50
No..........................................................................................................0
TOTALPOINTS............................................................................................. 65
1 If no surface or groundwater enters site, give 0 points.
APPENDIX 5—Site Plan with all applicable information (Minimum Size 11x17 at a legible scale)
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