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Home My WebLink AboutStorm Water 1-5 BLD-2018-0117 1406 O Avenue LERVIK ENGINEERING CIVIL DESIGN, CONSULTING AND CONSTRUCTION MANAGEMENT DRAINAGE REPORT F O R It/ ott , 1906 , / /o, o - T►p!ex ANACORTES• a9 ti ytY LERVIK ENGINEERING PO BOX 684 ANACORTES,WA 98221 360.588.1592 • LE RVIKENGINEERING.COM TABLE OF CONTENTS Background 5 SITE DESCRIPTION 6 On-Site Soils 6 Existing Conditions&Drainage Patterns 6 On-Site Basins 6 Off-Site Basins 6 Developed Conditions&Drainage Patterns 6 STORMWATER MANAGEMENT BMPs 7 MINIMUM REQUIREMENT#1: PREPARATION OF STORWMATER S►TE PLAN 7 MINIMUM REQUIREMENT#2: STORM WATER POLLUTION PREVENTION PLAN 7 MINIMUM REQUIREMENT#3: WATER POLLUTION SOURCE CONTROL 13 MINIMUM REQUIREMENT#4: PRESERVATION OF DRAINAGE SYSTEMS 13 MINIMUM REQUIREMENT#5: ON-SITE STORM WATER MANAGEMENT 13 SUMMARY 15 VICINITY MAP . , 1 I , .• I . p'Same •., - 1 Z.-_ v - .i, V0iUnteer Park I, ,•-: ----N _ . i > t' 1`-'' -- . - , -C ran b ef cartes Lake Pa .-.3 .,-,• , ,,•• rporl _ u , . .• 0 , I : 1 • 1st - 1 - _.... -... 1 .,. .., 34:3• -3 I - 1 ••-, ,.‘ • -. ? 7.::•,.3- i .. s" •I , I ,.. , , I ,. •-• • .0 r • CHARLIE ASH 1103 14TH STREET DRAINAGE:: REPORT, SEPTEMBER 2017 . . • . _ . . . Fog I 3 SITE DESCRIPTION This Drainage Plan Report contains a summary, analysis, maps and calculations to confirm that the proposed development complies with the City's requirements. On-Site Soils The NRCS maps the on-site soils as "BOW-URBAN LAND COMPLEX" and "CLALLAM-URBAN LAND COMPLEX" which are listed as Hydrologic Group "C/D" and "C" till soils, respectively. We performed a PIT test to determine the soil's suitability for infiltration.The excavation was 48" deep with the following soil profile: 0-2": Grass/lawn 2"-4": Topsoil consisting of roots, biomass,etc. 4"-28": Gravelly sandy loam 28"-48": Sandy silt,very damp (end of excavation) This is generally consistent with the description provided in the NRCS Soil Survey. Groundwater was observed seeping into the pit near the 28" BGE layer change.The excavation was covered and left overnight to establish groundwater.The water table was measured at 26" BGE;this is considered the restrictive layer for design purposes. Existing Conditions&Drainage Pans On-Site Basins The site is generally flat, with the nearby terrain sloping uphill to the west. A localized damp spot of perhaps 10 square feet was noticed near the northwest corner of the building.This could be the result of a utility trench collecting water,an area of groundwater under semi-artesian conditions, or other. No effort was made to determine the cause at this time;since this area will be located within the footprint of the new building, excavation and evaluation of the possible causes will be made during excavation for the foundations and mitigating measures,if required, will be made at that time. The total parcel size is 0.14 acres. Off-Site Basins Uphill from the site is a single-family home.The terrain flows gently downhill onto the subject property.Stormwater runoff will continue to flow onto the subject property and captured by footing drains. Developed Conditions &Drainage Patterns The new drainage regime will continue to function similar to the pre-development conditions, CHARLIE ASH 1103 14TH STREET DRAINAGE REPORT, SEPTEMBER 2017 Page 16 STORMWATER MANAGEMENT BMPs The following Elements are provided as outlined in the DOE Manual MINIMUM REQUIREMENT#1: PREPARATION OF STORWMATER SITE PLAN Step 1: Collect and analyze information on existing conditions See attached drawing(s). Step 2: Prepare preliminary development layout See attached drawing(s). Step 3: Perform off-site (upstream and downstream) analysis There are no significant upstream (off-site) areas. The solution agreed upon by the City results in no increase offlow from the site. As such, there will be no impact to downstream conveyance systems. Step 4: Determine applicable minimum requirements Minimum Requirements 1-5 are applicable. Step 5: Prepare a permanent stormwater control plan See analysis below. Step 6: Prepare a stormwater pollution prevention plan(SWPPP) See "Minimum Requirement#2" below. Step 7: Complete the stormwater site plan(SCC 30.63A.440). See associated drawings and exhibits. MINIMUM REQUIREMENT#2: STORM WATER POLLUTION PREVENTION PLAN TESC Element#1:Demarcation of Clearing Limits Prior to beginning earth-disturbing activities, including clearing and grading, all clearing limits will be clearly marked, both in the field and on the plans, to prevent damage and offsite impacts. CHARLIE ASH 1 103 14TH STREET DRAINAGE REPORT, SEPTEMBER 2017 Page 17 TESC Element#5:Soil Stabilization All exposed and un-worked soils will be stabilized by application of effective BMPs, which will protect the soil from the erosive forces of raindrop impact, flowing water • and wind erosion. From October 1 to March 31, no soils will remain exposed and un-worked for more than 2 days.This condition applies to all soils on site,whether at final grade or not. Applicable practices include, but are not limited to, temporary and permanent seeding, sodding, mulching, plastic covering, the early application of gravel base on areas to be paved or graveled, and dust control. Soil stabilization measures selected should be appropriate for the time of year, site conditions, estimated duration of use, and potential water quality impacts that stabilization agents may have on downstream waters or ground water. Soil stockpiles must be stabilized and protected with sediment trapping measures. Recommended BMPs BMP C120:Temporary and Permanent Seeding BMP C121: Mulching BMP C123: Plastic Covering TESC Element#6:Slope Protection &Stabilization Cut and fill slopes will be designed, constructed and maintained in a manner that will minimize erosion. Recommended BMPs: No BMPs proposed. No significant cut/fill slopes are anticipated outside the foundation excavation.The following BMPs may be used if necessary. BMP C 120: Temporary and Permanent Seeding BMP C121:Mulching BMP C 123: Plastic Covering TESC Element#7: Drain Inlet Protection Drain inlets installed by this project will be protected from sediment-laden flows, and • directed to sediment trapping facilities. Recommended BMPs BMP C220: Inlet Protection CHARLIE ASH 1 103 14TH STREET DRAINAGE REPORT, SEPTEMBER 2017 Page 19 Recommended BMPs The Contractor for the project shall obtain a copy of Department of Ecology's Stormwater Management Manual for Western Washington Volume IV Source Control BMPs. TESC Element#10: Control De-Watering All turbid de-watering water,which has similar characteristics to storm water runoff at the site,will be discharged into a controlled environment. Highly turbid or otherwise contaminated dewatering water,such as from the washing of construction equipment operation will be handled separately from storm water at the site. Disposal options may include: 1) infiltration by pumping to vegetated areas for dissipation 2) transport off-site in vehicle, such as a vacuum flush truck, for legal disposal in a manner that does not pollute state waters, or 3) on-site treatment using chemical treatment or other suitable treatment technologies. Recommended BMPs No de-watering is proposed for this project. TESC Element#11:Maintain BMPs All temporary and permanent erosion and sediment control BMPS will be maintained and repaired as needed to assure continued performance of their intended function. All maintenance and repair will be conducted in accordance with BMPs. Sediment control BMPs will be inspected after a runoff-producing storm event during the dry season and daily during the wet season. All temporary erosion and sediment control BMPS will be removed within 30 days after final site stabilization is achieved or after the temporary BMPS are no longer needed. Trapped sediment will be removed or stabilized on site. Disturbed soil areas resulting from removal of BMPs or vegetation will be permanently stabilized. TESC Element#12:Manage the Project The project will be conducted to prevent, to the maximum extent practicable, the transport of sediment from the development site during construction. Revegetation of exposed areas and maintenance of vegetation will be an integral part of the clearing • activities. Based on the information provided, and/or local weather conditions, the local permitting authority may expand or restrict the seasonal limitation on site disturbance. If, during the course of any construction activity or soil disturbance during the seasonal limitation period, silt-laden runoff leaving the construction site causes a violation of the surface water quality standard or if clearing and grading limits or erosion and sediment control measures shown in the approved plan are not maintained, the local permitting CHARLIE ASH 1103 14TH STREET DRAINAGE REPORT, SEPTEMBER 2017 Page I 11 • Keep all heavy equipment off existing soils under LID facilities that have been excavated to final grade to retain the infiltration rate of the soils. Recommended BMPs No specific LID components are proposed. • MINIMUM REQUIREMENT#3: WATER POLLUTION SOURCE CONTROL No pollution-generating activities are anticipated on this project.The contractor shall employ BMPs to prevent construction-related pollution. MINIMUM REQUIREMENT#4: PRESERVATION OF DRAINAGE SYSTEMS The stormwater on the site currently infiltrates or flows to the public stormwater drains in ()- Avenue.This flow pattern will continue. MINIMUM REQUIREMENT#5: ON-SITE STORM WATER MANAGEMENT The objective of this MR is to "reduce the amount of disruption to the natural hydraulic characteristics of the site." Preservation of the "natural hydraulic condition" is achieved by directing the site's runoff to on-site infiltration systems or the storm system located in 0-Avenue. List#1: On-site Stormwater Management BMPs for Projects Triggering Minimum Requirements #1 through #5 For each surface, consider the BMPs in the order listed for that type of surface. Use the first BMP that is considered feasible. No other On-site Stormwater Management BMP is necessary for that surface. Feasibility shall be determined by evaluation against: 1. Design criteria, limitations, and infeasibility criteria identified for each BMP in this manual; and 2. Competing Needs Criteria listed in Chapter 5 of Volume V of this manual. LAWN AND LANDSCAPED AREAS ✓ Post Construction Soil Quality and Depth in accordance with BMP T5.13 in Chapter 5 of Volume V. ROOFS REQUIREMENT FEASIBILITY/INFEASIBILITY JUSTIFICATION Discharges to SALT WATER Downspout Full Infiltration-BMP 1-5.10A DOWNSPOUT FULL INFILTRATION (BMP T5.10A)is infeasible due to the depth to groundwater. Downspout Dispersion-BMP T5.10B DOWNSPOUT DISPERSION is INFEASIBLE due to lack of dispersion distance from dispersion point to property line. CHARLIE ASH 1103 14TH STREET DRAINAGE REPORT, SEPTEMBER 2017 Page 113 SUMMARY The site conditions preclude the use of BMPs for roof runoff. The shallow groundwater table that, after a very dry summer with very little rain, was located roughly 26 inches below existing grade.This does not provide adequate separation between the bottom of the various trench options and the restrictive layer. The site's flat terrain allows for the use of dispersion for the driveways.The driveway will be sloped to direct runoff onto the adjacent lawn to the greatest extent possible.The driveways along the alley and near the roadway will drain to the street where it will flow to the storm drainage system. CHARLIE ASH 1 103 14TH STREET DRAINAGE REPORT, SEPTEMBER 2017 Page 115 LEGAL DESCRIPTION: LOTS 1 AND 2,BLOCK 54,ANACORTES,RECORDED IN VOLUME 2 OF PLATS,PAGES 4 TO 7,RECORDS OF SKAGIT COUNTY, WASHINGTON. 20' 20 LERVIK ENGINEERING PO BOX 684 ANACORTES, WA 98221 360.588.1592 CHARLIE ASH 1 103 14th STREET, ANACORTES STORMWATER SITE PLAN 2 __ ---- R - . - ---- Catch Basin filter GullyWasher Filter by Aqua Treatme or appoved equc 18 ____________. iylirl ,, 1 i - 1 I . i __,....„...._ , . HI AG/ INLET PROTECTION (BMP C220) Not to Scala F • i JOINTS IN FILTER FABRIC SHALL BE SPLICED -. AT POSTS. USE STAPLES, WIRE RINGS OR ? EQUIVALENT TO ATTCH FABRIC TO POSTS • EQUIP, r; 4 4Y Ca. ,� r�' r _ i r -t ry �- -vti- TA (.�T%` i Z�cr�i�t 0i.J_9�4�>a t-r r r i�sr�� r-„r' x-� i fit ` 1 .1P±- t'- YC v��.k�c�``�ri�L��Ftv }Lj 4 h Y .Ix751. ��s� i 4. j..�£ftF-4 .c 1 psiV#A. ��y.-*�*7'1g e c..ry*Y'+C''w 6 6' MAX 1 3 i i"s NNNN POST SPACING MAY BE INCREASED 1 TO 8' IF WIRE BACKING IS USED 2 x2,� 1 P SILT FENCE DETAIL PIMP C233) 62 ) s Not to Scale l 1 i 5 f ' f t i l . VIENGINEERING PO BOX 684 ANACORTES, WA 98221 360_588.1592I ` CHARLIE ASH I 1 103 14th STREET, ANACORTES D ETA I LS yi 1 i el '11 ' z-T4* *„, most 44 43' :, 6-4 14 th STREET I 14 th STREET AS SEWER NEW 5' WIDE SIDEWALK , STORM SEWER `� h. CITY WATER \TOKM At STORM 1 �.O C ( 0.SCR-I PrI0I`•J CITY WATER 0 1 ' o WHEELCHAIR ACCESS _ ---_ ` R�1) ,2 -rowkt amES Ci AT CAc N POWER POLE I ELECTRICAL POWER �_,I pg Q� X IST/�l�c RE Slj}£r,IC£) POWE', POLE � PER 2.®IS 1 .2 .C . S€�-77on� R.3o� r \ ei \ 59.94' �� .� I \ 59.94' i 9D I, LOT IS FLAT I NO SLOPE 13' I I 5 I 7'-32" 4" FOOTING DRAIN 19'- 12' / ROOF DRAIN _III PORCCT1 /III PORCH p 33.6' �� F__�_- _-� DOWNSPOUT CITY OF AIVAt OR 1 TYP P � t i" 7 EXISTING EXISTING K Dot- ( ) �Cf r7` J6• A 1 r HOUSE HOUSE KITCHEN J PE 9 d in - r F»=3�1 DINING ING jI Q PERMIT i E �y 6" PIPE hi p ADDRESS. 20. 1 ' , . cn APPROVED$Y; v • 5 W �;� 11 111 (�w �,01;;�30 la ' O SUBJECT TO FIELD INSPECTION. ILI Powoe l APPROVED PLANS $ DE K` J` SHALL NOT BE ALTERED WITHOUT AUTHORIZATION. J 3r— =1 ; X �I z DECK DINING LIVING ' 16 / 1 I --J •: DINING LIVING L Z I 1 1 KITCHEN 11--1 CITY OF ANACORTES KITCHEN -- �� at > > B r '� PLANNING & BUILDING DEPT: a �ma�;i; o o �� o AP ROVED PLANS 0 o L �� ^��„�I L I o 8 tit VED • r�ere: w ' awd ae, I�r -'! o a O O 4�'I ,mI i BATH, — — , i sArH, _ — PERMIT#. 8 11GM I I B WANG 1, __ - NEM I d..E-AAl \ F '/�X)J 0 __y L3J �1 L,.J��II f___,F-----...1 F J II I VJi.L_. 1 — V '— 4 �� J o f"' CLOSET r=_�Ili __��_ s__ /L CLOSET —J 0 ADDRESS: I7 ®�•• 0 L/� Ir CLOSET ;I LIEN — (CLOSET "L4N A - �a�//(" ` APPROVED$Y: - , ® —k �;' » ��-- 1 SUBJECT TO FIELD INSPECTION. APPROVED PLANS Be drooNm 3 Bedroom SHALL NOT BE ALTERED WITHOUT AUTHORIZATION. Bedroom Bedroom I \ B,.Gf,�NG ,L 5' O. ' I'O [1 OPEN EXISTING CURB CUT TO 20 8.6 I a I • L 1 / INSTALL TYPE I - PAY LIMIT J • = f Ll aoNoe T -rnr-_ 1 DRIVEWAY PER STD. PLAN I ' �7I1 ,,w; w,DL1� 0 IL ! 11AA �, n F80. IO04 /^�-� --- -L-' `-' 6JL " "`3 / 4,08 Mid, o GENERAL z / CITY OF ANACORTES CAR PORT GENERAL SYSTEM I r - a,\`_ ��. �I SYSTEM20' Z Z I -z o • 0 1=a PLANNING & BUILDING DEPT: STORAGE J L , - ? 5� rlydintG LIVING Xm ROOF, FOUNDATION DRAIN, * �P\WEWAY GRAVEL ' ReFrz, r----� Q =F 1;1 W D •-R&N-Off TO BE PIPED TO CATCH BASIN APPROVED PLANS ii 0 GTE o I KITCHEN 'l1 o111] AT CORNER OF "O" $ 14th. PERMIT#: �� , -o j 1,°_,,e4itier O (3 ow7-� ,I I PER ENGINES FINDINGS ADDRESS j Q * __ ,_,,,}Li.: L `. � ,E__Oc -3 GTE r 1 i' -- — 4- 0 �ft Sl cei� Y�uIS APPROVED ' SIDEWALK O O O �p { gp GRAVEL GRAVEL \ GRAVEL ' 3�_,d/u`� ✓r o✓t- stt e eracibA SUBJECT t. } IJ 2 It;\ f-n Pr NS5 , 20.3' `� ,E1 16' 4" o �A+ask• ic] • SHALL NOT BE , ,, It, t. , �r �� I )�sl 9, nPOLE POWER POLE I)} o K J t j ' £M.P Tc (3 Po r (o nrdvvat,n LLSrn ( �d�a�` P 0% •. �� 1 8' att 4154- amt., f t"felt' 77) taA:ez.1� exc u�^'`? —� 59.93' �'� : 9.9 :..: �2 . . . :F : . 1 . . . .': . . .-.' .'. . . . . .". . . . .•:". . . . . . C.:.:.: R4 ZONING BUILDER TO VERIFY ALL DIMENSIONS . .. ... . .. •'-'•. . . . . . . . . . . . + s ` + ♦.. .• `.+ - .. .-.I .•.•. CONSTRUCTION NEEDS TO COMPLY WIiH ALLEY ` + F r. . .` 2015 WASHINGTON STATE ENERGY CODE (WSEC) . � LIB ............................................... ....... ` .. .'• - • - . . •'.'.'... . • ..-(.`.:.` BUILDING TO COMPLY WITH THE IRC 201 5 BUILDING CODES EXISTING SITE PLAN i�ii ZoUSBINFTOCOMPLY O PLYWI HTHE LOT SQ. FT. = 5995.8 NEVV ASPHALT ALLEY N FW SITE PLAN CB `TYPE I > 1 REV. # I 03/02/ 18 SCALE: I " = I 0'-0" I of I 0 HOUSE FOOT PRINT SQ. FT.= 1347 DRAWING INDEX: PERCENT OF COVERAGE= 22% LI I . EXISTING $ NEW SITE PLAN TRIPLEX FOOT PRINT T S Q. FT.= 2238.8 SITE PLAN MAR o s '"' EXISTING IMPERVIOUS AREA 2. EXISTING $ NEW EAST $ WEST ELEVATIONS PERCENT OF COVERAGE= 37.3% HOUSE, CARPORT CONCRETE PORCH 3. EXISTING $ NEW NORTH $ SOUTH ELEVATIONS CHARLIE ASH TRI FLEX , DRIVEWAY * SIDEWALK 1657 SQ. FT. 4. EXISTING $ NEW MAIN FLOOR PLAN NEW IMPERVIOUS AREA 5. NEW UPPER FLOOR PLAN TRI FLEX, PARKING , CONCRETE PORCH PERCENT OF IMPERVIOUS AREA 27.6% 6. NEW FOUNDATION PLAN DRIVEWAY SIDEWALK 3304 sQ. FT. ADDRESS : 1103 I 4th STREET 7. UPPER FLOOR FRAMING PLAN 8. NEW ROOF PLAN PERCENT OF IMPERVIOUS AREA 55% PARCEL: r 55235 9. SECTIONAL DETAILS I O. BRACE WALL LINES PLANS DRAWN BY: DRUCE RUSTAD DATE: O5/26/ 1 7