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Permit File BLD-2019-0629 1207 6th Street (4)
G1� Y O Storm Water Minimum Requiremen ENGINEERING DEPARTMENT MAY 3 2019 i� ' c f ;;! 904 6`''Street Anacortes,WA 98221 www.anacorteswa.gov `,� lTY OF ANACORTES � � SEP 2 7-2019 . Official Use Only: (Information to Inspectors) FILE COPY Required Storm Water Facility and other related requirements: �rnQ T'5.1?, ec r IS De232, Th �tZeO 1t) F rrP M b.R .—..pI . `1 f3rn p r S.141L -trn I N 6p L j . cot-2- c2-4=c —S t=in..c s`` Project Address: I TI j I tot 11 5r Submittal Date: l 1 Parcel Number: P 553'7 g Revision Number: 1 Permit Number: '1i L D 2O i q•-0 6`Lj Acceptance Date (COA): Reviewer: S1, .j _ FRONT OF REPORT i.zt,.Iq•512_k- Submittal Checklist: o TAB#1 through #6- Drainage Analysis- Minimum Requirement#1 to#� Waz wrtN �' ,el APPENDIX 1 - Survey performed by a Professional Land Surveyor N�" � 11L�`^5 �-��lv' APPENDIX 2 - Soils Analysis (Volume 1, Chapter 3.1.1) Go. 12.19 ISL ra' APPENDIX 3 - Model Soil Management Plan for BMP T5.13 de APPENDIX 4 - Determining Construction Site Sediment Damage Potential (Appendix 7) 7o APPENDIX 5 - Site Plan with all applicable information (Minimum Size 11x17-30 scale) p- APPENDIX 6 - Documented Site Photos (North, South, East and West) 70 APPENDIX 7 - Drainage BMP Facility Maintenance Covenant, if applicable. To be recorded prior to the Temporary Certificate of Occupancy, Certificate of Occupancy or Final Acceptance. Project Description: (What is it you are looking to do? Provide details regarding, but not limited to, Lot SF, Home SF, New and Replaced Hard Surface) Construct a new 1922 square foot single family home and a detached two car garage with 662 square foot Accessory Dweling Unit above garage. Lot is vacant, 10,500 square foot(0.23 acre). New hard surfaces (same as impervious surface) is 4,658 square feet. Existing Site Conditions Summary: (Additionally, provide information on previous permits, if any, like Grade and Fill, Clear and Grade, topography, vegetation, drainage, Critical Areas adjacent to the site and how it may affect this project if soils are disturbed, Soils Type (Included in Soils Analysis Report), Erosion Problem Areas, Construction PhasinglSequence) Only pervious permit was a demo permit taken out on 3/23/2016;:'renewed on 4/17/2017. Existing house was demoed 05/04/2017. There are no Critical Areas adjacent to site. Soils Type are detailed in the attached Geotechnical Report. Topography of the site is flat+/- 1.5 feet,with exception of an embankment on the north property line, adjacent to and parallel with the city sidewalk on Sixth Street. The embankment extends the full Version Date: February 20, 2019 length of the north property line and varies in height from 4 to 5 feet. Vegetation on the site is grasses and weeds. There are no Erosion Problem Areas. Developed Conditions Summary: (Additionally, to be shown on the site plan. Identify cut and fill areas, proposed slopes of all hard surfaces , proposed contours) There will be no cut and fill areas. The only hard surface slope will be the concrete steps from the city sidewalk up to grade level (approx. 5 feet high) at a slope of 7:12. At the SE corner, between the fence and the curved 18 inch high landscape wall, approximately 600 square feet will be filled above existing grade to the top of the landscape wall with a mix of excavation soils and imported top soil. This area will be landscaped. At the north property line a reinforced concrete retaining wall will be built, 4 feet high by the full width of the property. Where the retaining wall is below grade it will be sloped at a 3:1 grade to the existing grade. The wall will be faced in native stone to match existing walls in the neighborhood. Provide the Infiltration Rates found during the rainy season: At NW corner, 0.311nchs Per Hour; at SE corner, 1.77 inches per hour. What was the depth of the ground water table?No groundwater encountered at maximum depth of test pits, 5 feet BPG. Feet and Inches below existing grade (See completed Soils Analysis (Volume 1, Chapter 3.1.1) Site Sediment Transport Score: 70 Total Points (Hig \Low) See Determining Construction Site Sediment Damage Potential(Appendix 7) Drainage Basin(2007 Storm Comp Plan—City website\publicworks\engineering\comprehensive plans): What Drainage Basin are you in? le Identify any downstream drainage issues (Storm Comp Plan: If so, describe: No downstream drainage issues known. Complete the Applicability Requirements— Flow Chart(Figure 1-2.4.1 Attached, Figure 1-2.4.2 Attached and Figure 1-2.5.1 Attached) - Highlight the path and attach DOE Stormwater Management Manual Minimum Requirements: (MR#1 to MR#9 only). Refer to the 2012 Department of Ecology Manual, as amended in 2014 for further required information. Version Date: February 20, 2019 Start Here Does the site stave 35% Yes See Redevelopmert n mum or more of existing Requirements and F ow Chart impervious coverage? (Figure I-2.4.2). `� lVo Does the project convert' V acres or more of vegetation to Does the project result ir lawn or landscaped areas, or 5.0(10 square feet, or No convert 2.5 acres or more of greater. of new pus /► natve vegetation to pasture? replaced hard surface area? No Yes Yes Does the project result ir 2.000 square feet, or greater, of new phis All Minimum Requirements replaced hard surface area? apply to the new and replaced hard surfaces and converted Yes No vegetation areas_ Does t*ie project have land Minimum Requiner�r ents�#t aisturbing activities of 7,000 through #5 apply to the new 411 Yes scuare feet or greater? and replaced hard surfaces and the land disturbed_ No f Minimum Requirement#2 e_c_u_ � 11.2 5 t5 applies_ SIZE 111 Figure 1-2_4_"I Flow Chart for Determining Requirements for New Development DEPARTMENT CF Revised June 1€ ECOLOGY Ple3se see,hr:: 4r e-64.e_y.tve.gotOcopyrigen.tirml for copyright notice Including permissions, 313 to of Vii'35 n I n a o i ninny of iiaollity,and disdain•er. version uate: reoruary Lu, zu-i y TAB 1 (MINIMUM REQUIREMENT #1) • 1-2.5.1 Minimum Requirement#1 — Prepare a Stormwater Site Plan - 1.3— Preparation of a Stormwater Site Plan - 1.3.1 —Stormwater Site Plans: Step-by-Step Note: The level of detail needed for each step depends upon the project size. Provide a narrative description of each step. 1-3.1.1 Step 1 - Site Analysis: Collect and Analyze Information on Existing Conditions Site analysis shall be submitted as part of the Existing Conditions Summary above. Part of the information in this step should be used to help prepare the Construction Stormwater Pollution Prevention Plan. Purpose of the Site Analysis is to provide for a Low Impact Development site design that is intended to compliment the predeveloped conditions of the site. Survey and Geotechnical Report have been completed and analyzed. 1-3.1.2 Step 2 - Prepare Preliminary Development Layout Based upon the analysis of existing site conditions, locate the buildings, roads, parking lots, landscaping features, on-site stormwater management BMP's, and preliminary location of stormwater treatment and retention/detention facilities for the proposed development. Based upon analysis of site conditions, best stormwater retention facilities are located on NW and SE corners of property. NW corner is a low spot (swale) and the only feasible location for a rain garden without disturbing the natural grade. SE corner has much better soil infiltration rate (1.77 inches per hour) and is the logical location for dry well(s). Therefore the house is located at the NE corner of the property, and the garage/ADU is located at the SW corner within required setbacks. For both the house and the garage/ADU, impervious areas are minimized by the design of two storey structures, requiring smaller foundations than a one storey structure. 1-3.1.3 Step 3 - Perform Off-site Analysis (at Local Agency's Option): Use additional Sheets, if necessary, Ecology recommends that local governments require an off-site analysis for projects that add 5,000 SF or more of new hard surfaces, or convert'A acres of vegetation to lawn or landscape areas, or convert 2.5 acres of forested area to pasture. Off-site analysis extends to '/4 mile downstream of the project site. This project adds less than 5000 square feet of new hard surfaces. 1-3.1.4 - Determine Applicable Minimum Requirements Establish project size thresholds for the application of Minimum Requirements to new development and redevelopment projects. Figures 2.4.1 (Attached) and 2.4.2 (Attached) provide the same thresholds in a flow chart format. Based on the preliminary layout, determine whether Minimum Requirements#1 through #5 apply to the project; or, whether Minimum Requirements#1 through#9 apply. Please note, that Minimum Requirement#1 through #5 may trigger additional Minimum Requirements, such as Flow Control. Version Date: February 20, 2019 Minimum requirements #1 through #5 apply to this project. See figure 1-2.4.1 Flow Chart. 1-3.1.5 Step 5 - Prepare a Permanent Stormwater Control Plan (Refer to this section of the Ecology Manual for requirements.) See "Permanent Stormwater Control Plan" site plan. Total impervious area of the finished project will be 4,658 square feet. Soils on the site are suitable for infiltration (see Huber Residence 47 Geotechnical Report, section 5.6). Specifically, soils at the SE corner of the site have high RXv _ infiltration rate (1.77 inches per hour). r0f ^f�'r�� efl to infiltrat ronf r��n f�„ he /, so faeincroof of the house (85 Srn.are f"Pth is app nrnriata in + . n. ,.. The remainder of the impervious surface area is 3,806 square feet. Duc-to lack of sufficient fiy , ' es wou rHn- hrort jade. BMP for remaining stormwater control is a rain garden, shown on the plan. Calculations for rain garden are as follows: 3,806 square feet impervious area reduced by 350 square feet for flow control credits for newly planted trees (5 evergreen trees X 50 Sq. Ft; 5 deciduous trees X 20 Sq. Ft; total 350 Sq. Ft. credit per Table III-C.2, 2014 SWMMWW). This leaves 3,456 Sq. Ft. impervious surface area to be infiltrated. According to 2014 SWMMWW BMP T5.14A, the rain garden shall have a ponding surface area below the overflow of at least 5% of the impervious surface area draining to it, or 173 square feet in this case. Due to the marginal soil infiltration rate of 0.31 inches per hour for this area of the property, the ponding surface area of the rain garden has been increased by approximately 70% to 290 square feet. Location of rain garden: The NW corner of the site is a natural swale and is about 1 foot lower in elevation than grade at both house and garage/ADU. Locating the rain garden here requires minimal regrading or altering of the natural topography. Downspout and other drains will have enough elevation change to flow adequately. Overflow and footing drains: A natural or lawn area of moderate slope and adequate size below the rain garden does not exist on the site, so per previous consultation with City of Anacortes Public Works Engineering staff a storm drain hookup will be made for the rain garden overflow. This storm drain connection will also take the footing drain from the house and the footing drain at the base of the retaining wall at the north property line. These footing drains are too low to drain to daylight or anywhere else. The overflow/footing drain pipe will go below the retaining wall footing, under the sidewalk along 6th Street, then east in the planting strip 135' to the stormwater connection at the SW corner of 6th Street and N Avenue. The downhill slope of 6th Street towards the east allows for the required minimum '/2% slope to the storm drain connection and also the minimum 1 foot cover above the buried pipe. 1-3.1.6 Step 6 - Prepare a Construction Stormwater Pollution Prevention Plan (MR#2 — 13 Elements) Refer to Chapter 11-3—Planning for a detailed description of each element. See also attached Tables 4.1.1 (Source Control BMP's by SWPPP Element) and Table 4.2.1 (Runoff Conveyance and Treatment BMP's by SWPPP Element). See attached 13 Elements of a SWPPP, please complete and attached Version Date: February 20, 2019 1-3.1.7 Step 7 - Complete the stormwater site plan The Stormwater Site Plan encompasses the entire submittal to the Local Agency with drainage review authority. Refer to this section of the Manual for further clarification of each item and what is required. See below: • Project Overview • Existing Conditions Summary • Off-site Analysis Report • Permanent Stormwater Control Plan • Construction Stormwater Pollution Prevention Plan • Special Reports and Studies • Other Permits • Operation and Maintenance Manual • Declaration of Covenant for Privately Maintained Flow Control and Treatment Facilities. (See attached Drainage BMP Maintenance Covenant BMP Agreement) • Declaration of Covenant for Privately Maintained On-site Stormwater BMP's (See attached Drainage BMP Maintenance Covenant BMP Agreement) • Bond Quantities Worksheet, if applicable �125• 19 ALL TO\As " c14�21c_�.�ST e iT4.= Pp-be a4x GLA-10 -> S 1-3.1.8 Step 8 - Check Compliance with all Applicable Minimum Requirements A Stormwater Site Plan as designed and implemented should specifically fulfill all Minimum Requirements applicable to the project. The Stormwater Site Plan should be reviewed to check that these requirements are satisfied. All Applicable Minimum Requirements that apply to this project have been reviewed and satisfied. Version Date: February 20, 2019 TAB 2 (MINIMUM REQUIREMENT#2) • 1-2.5.2 Minimum Requirement#2—Construction Stormwater Pollution Prevention Plan (SWPP) - All projects are required to complete Minimum Requirement 2. - Refer to the 13 Elements of the SWPP (See document below, complete and attach) - See attached Table 4.1.1, Table 4.2.1 and Table - Provide Engineering Calculations as an attachment for Sediment Ponds\Traps, Diversions, Waterways and Runoff/Stormwater Detention Calculations. Version Date: February 20, 2019 Table 4.1.1 Source Control BMP's by SWPPP Element Element#1 Element#2 Element#13 Element#5 Element#6 Element#9 Element#11 Element#12 Preserve Establish Protect Low BMP or Element Name Stabilize Protect Control Maintain Manage the Vegetationtivlark Construction Soils Slopes Pollutants BPv1Ps Project Impact Clearing Limits Access Development BMP C101: Preserving Natural Vegetation BMP C102: Buffer Zones ✓ ,� BMP C103: High Visibility Plastic or Metal V Fence BMP C105: Stabilized Construction J Entrance /Exit BMP C106: Wheel Wash ✓` BMP C107: Construction Road/Parking Area Stabilization BMP C120:Temporary and Pernnnent V Seeding BMP C121: Mulching V ✓ BMP C122: Nets and Blankets ✓ .7 BMP C123: Plastic Covering ✓ BMP C124: Sodding +� BPv9P C125: Topsoiling /Composting ✓ BPv9P C126: Polyacrylamide for Soil Erosion Protection BMP C130: Surface Roughening ✓ V BMP C131: Gradient Terraces ✓ BMP C140: Dust Control BMP C150: Materials Can Hand V .� BMP C151: Concrete Handling ✓ BMP C152: Savvcutting and Surfacing Pollution Prevention BMP C153: Material Delivery, Storage and V Containment BMP C154: Concrete Washout Area BMP C160: Certified Erosion and Sediment Control Lead BMP C162: Scheduling Version Date: February 20, 2019 Table 4.2.1 Runoff Conveyance and Treatment BMP's by SWPPP Element Version Date: February 20, 2019 4 _________ • Eiernentilt4 Element#6 Element tit Element Oa Element"13 Element/3 Element eta Fir irc.nt tin nstall Stabill2a CBMP or Element Name Control I Pit:tart Rioted 1 Control ntrilDe Prattl Low Sediment Chnnnois impact , Flow gales Slopes Drain Ink% Pollutants 'Nutt.'ll'iu C .. t •Is and Outlets )orelopment , 3a1t3 G2041: Interceptoi Dike and Swale let ] BM P C201:. Grass-tined Channels 4.7 MAP C2.02:Channel Lining] V 131111P C20:71; Water Bars vi vr - 811IP C204: Pipe Slope Drains V rirmIP C206: Subsorface Drains se' 1...---....,--- __. - , 8MP C206: Level Spreader ./. taMP C207: Check Darns V ---1----"' filkIP c 20a: Triangular S'ill Dim (Gleotexille V. Locased Check Carn) EiMP C209: Outlet Protection ve BMP C220: Storm Drain inlet Protection- / BfriP C231: Brueti Barrier ite f BMP C232; Gravel Filter Senn vi —1 _ — Earrip C231: Sit Fence / v BrilP C234: Vilaetale-d altlp it' 47 _ ..... 13MP C236: Wattles V _____ .--- --, BMP C236-. Vegltutive: Filtration I BMP C24ik Sodirnont Trap V 1 BMP C-2411 Temporary Setheneni.Pond V V 1 . . _ BMP C2511: Construction Stonnarsiter Cheeks!Treatment BMP C2511:Construction Storm/filer Filtration if BMP C252 High pH Neutralization paint) I ! If CO2 • _________ BMP C2S3:pH Control for High p11 Inater I V . , 1 , 13 Ellemonts of STOPPP Version Date: February 20, 2019 (Construction Stormwater Pollution Prevention Plan) Please check off boxes to show that each element has been read and understood. Provide details where applicable and if certain aspects are unnecessary or exempt, clearly justify. Details of the 13 Elements and the correlating BMPs are listed Above from the 2014 Stormwater Management Manual for Western Washington (SWMMWW). A link is provided on the City of Anacortes website, under Planning, Community, & Economic Development Department, as well as under Stormwater on the Engineering Division of Public Work's page. Owner Name: Michael Huber Site Address:_1211 Sixth Street, Anacortes, WA 98221 Prepared By: Michael Huber ►2-bto-lck The Stormwater checklist or building permit determined that: i 1' ' 1b non �� € The 13 elements must be addressed These elements must be addressed for construction activity adding under for construction activity adding 2,000 2,000 sq. ft. of hard surface area. sq. ft. or more of hard surface area. This means that an attached narrative and site plan are required with this document. Under each element, explain the best management practices (BMPs) used or justify reasoning for those that will not be used. If needed, please attach a narrative to further explain plans or justification. ELEMENT 1: Preserve Vegetation/Mark Clearing Limits € Before beginning land disturbing activities, including clearing and grading, clearly mark all clearing limits, sensitive areas and their buffers, and trees that are to be preserved within the construction area. € Retain the duff layer, native top soil, and natural vegetation in an undisturbed state to the maximum degree practical. y,�,�¢., i iv a ► Silt fencing (BMP C233)where appropriate and high vis plastic fencing (BMP C103) to be erected on all property lines prior to any construction activity. There are no sensitive areas, buffers,trees or natural vegetation (weeds only) on the site. Any excavation will be limited to the building foundations and required trenching to the extent possible, so as to retain native top soil and duff layer(BMP C101). ✓ELEMENT 2: Establish Construction Access € Limit construction vehicle access and exit to one route, if possible. € Stabilize access points with a pad of quarry spalls, crushed rock, or other equivalent BMPs, to minimize tracking onto roads. € Locate wheel wash or tire baths on site, if the stabilized construction entrance is not effective in preventing tracking sediment onto roads. € If sediment is tracked off site, clean the affected roadway thoroughly at the end of each day, or more frequently as necessary (ex: wet weather). Remove sediment from roads by shoveling, sweeping, or pick up and transport the sediment to a controlled sediment disposal area. € Conduct street washing only after sediment is removed in accordance with the above bullet. € Control street wash wastewater by pumping back on site or otherwise preventing it from discharging into systems tributary to waters of the State. Version Date: February 20, 2019 Construction access will be from the gravel alley at the south side of the site. The access point will be stabilized with crushed rock as required (BMP C 105). The alley and nearby roadway will be monitored to ensure no sediment is tracked onto roads. Any sediment/debris tracked onto roadways will be cleaned up promptly. ELEMENT 3: Control Flow Rates € Protect properties and waterways downstream of development sites from erosion and the associated discharge of turbid waters due to increases in the velocity and peak volumetric flow rate of stormwater runoff from the project site. € Where necessary to comply with the bullet above, construct stormwater retention or detention facilities as one of the first steps in grading. Assure that detention facilities function properly before constructing site improvement (e.g. impervious surfaces). € If permanent infiltration ponds are used for flow control during construction, protect these facilities from siltation during the construction phase. Other than the 4'-5' embankment at north property line, the site is essentially flat, with no stormwater runoff or erosion having ever been observed. Therefore no sediment traps or sediment ponds are required. All major excavation (for building foundations) is expected to be completed during the summer dry season (BMP C162). During construction of the front retaining wall the slope behind it will be monitored for any runoff or erosion and straw wattles will be placed as necessary. (BMP C235; BMP C233). 'ELEMENT 4: Install Sediment Controls € Design, install, and maintain effective erosion controls and sediment controls to minimize the discharge of pollutants. € Construct sediment control BMPs (sediment ponds, traps, filters, etc.) as one of the first steps in grading. These BMPs shall be functional before other land disturbing activities take place. € Minimize sediment discharges from the site. The design, installation and maintenance of erosion and sediment controls must address factors such as the amount, frequency, intensity and duration of precipitation, the nature of resulting stormwater runoff, and soil characteristics, including the range of soil particle sizes expected to be present on the site. € Direct stormwater runoff from disturbed areas through a sediment pond or other appropriate sediment removal BMP, before the runoff leaves a construction site or before discharge to an infiltration facility. Runoff from fully stabilized areas may be discharged without a sediment removal BMP, but must meet the flow control performance standard in Element#3, bullet#1. € Locate BMPs intended to trap sediment on-site in a manner to avoid interference with the movement of juvenile salmonids attempting to enter off-channel areas or drainages. € Provide and maintain natural buffers around surface waters, direct stormwater to vegetated areas to increase sediment removal, and maximize stormwater infiltration. € Where feasible, design outlet structures that withdraw impounded stormwater from the surface to avoid discharging sediment that is still suspended lower in the water column. The site will be monitored throughout construction for any evidence of sediment or pollution discharge from the site. The NW corner of the site (where the rain garden will be), is a natural swale and should collect any on site runoff(BMP C241). If any runoff is observed straw wattles (BMP C235) and/or additional silt fencing (BMP C233) will be placed appropriately so as to direct and control any runoff. All major soil disturbing activities are expected to be completed during the summer dry season (BMP C162). The rain garden and dry well is expected to be completed and fully functional by Oct.1. All downspout drains and other hard surface drains will be connected and empty into the rain garden/dry well at that time. /ELEMENT 5: Stabilize Soils € Stabilize exposed and unworked soils by application of effective BMPs that prevent erosion. Applicable BMPs include, but are not limited to: temporary and permanent seeding, sodding, mulching, plastic Version Date: February 20, 2019 covering, erosion control fabrics and matting, soil application of polyacrylamide (PAM), the early application of gravel base early on areas to be paved, and dust control. € Control stormwater volume and velocity within the site to minimize soil erosion. € Control stormwater discharges, including both peak flow rates and total stormwater volume, to minimize erosion at outlets and to minimize downstream channel and stream bank erosion. € Soils must not remain exposed and unworked for more than the time periods set forth below to prevent erosion. o During the dry season (May 1 —Sept 30): 7 days o During the wet season (Oct 1 —Apr 30): 2 days € Stabilize soils at the end of the shift before a holiday or weekend if needed based on the weather forecast. € Stabilize soil stockpiles from erosion, protect with sediment trapping measures, and where possible, be located away from storm drain inlets, waterways, and drainage channels. € Minimize the amount of soil exposed during construction activity. € Minimize the disturbance of steep slopes. € Minimize soil compaction and, unless infeasible, preserve topsoil. Exposed soils shall be dealt with to prevent erosion and dust. BMP for this project will be temporary seeding of exposed soils (BMP C120), and minimizing the amount of soil exposed during construction activity. Any soil stockpiles will be covered with plastic sheeting according to the schedule above, or sooner if weather forecast dictates (BMP C123). Any stormwater discharges will be monitored and dealt with as detailed in Element 4 above. Q GAZ( - hnvN-GN ✓ELEMENT 6: Protect Slopes € Design and construct cut-and-fill slopes in a manner to minimize erosion. Applicable practices include, but are not limited to, reducing continuous length of slope with terracing and diversions, reducing slope steepness, and roughening slope surfaces (Ex: track walking). € Divert off-site stormwater (run-on) or ground water away from slopes and disturbed areas with interceptor dikes, pipes, and/or swales. Off-site stormwater should be managed separately from stormwater generated on the site. € At the top of slopes, collect drainage in pipe slop drains or protected channels to prevent erosion. o *Temporary pipe slope drains must handle the peak volumetric flow rate calculated using a 10- minute time step from a Type 1A, 10-year, 24-hour frequency storm for the developed condition. Alternatively, the 10-year, 1-hour flow rate predicted/indicated by an approved continuous runoff model, increased by a factor of 1.6, may be used. The hydrologic analysis must use the existing land cover condition for predicting flow rates from tributary areas outside the project limits. For tributary areas on the project site, the analysis must use the temporary or permanent project land cover condition, whichever will produce the highest flow rates. If using the Western Washington Hydrology Model (WWHM) to predict flows, bare soil areas should be modeled as "landscaped" area. o Where 15-minute time steps are available in an approved continuous runoff model, they may be used directly without a correction factor. € Place excavated material on the uphill side of trenches, consistent with safety and space considerations. € Place check dams at regular intervals within constructed channels that are cut down a slope. € Consider soil types and its potential for erosion. € Stabilize soils on slopes, as specified in Element 5. € BMP combinations are the most effective method of protecting slopes with disturbed soils. Ex: Use both mulching and straw erosion control blankets. The only slope on the site is the 4'-5' high embankment along the north property line. Currently this slope is Version Date: February 20, 2019 fully vegetated and stable. There will be minor excavation at the bottom of this slope for pouring of the concrete footing, and then the concrete wall. As soon as practicle the area immediately behind the new retaining wall (4' high) will be backfilled, eliminating most of the slope. This will be complete by Oct. 1st Until then the existing slope will be monitored for any runoff or erosion and temporarily reseeded(BMP C120) and/or straw mulched (BMP C121) as required. ✓ ELEMENT 7: Protect Drain Inlets € Protect all storm drain inlets made operable during construction so that stormwater runoff does not enter the conveyance system without first being filtered or treated to remove sediment. € Clean or remove and replace inlet protection devices when sediment has filled one-third of the available storage (unless a different standard is specified by the product manufacturer). € Where possible, protect all existing storm drain inlets so that stormwater runoff does not enter the conveyance system without first being filtered or treated to remove sediment. € Keep all approach roads clean. Do not allow sediment and street wash water to enter storm drains without prior and adequate treatment unless treatment is provided before the storm drain discharges to waters of the State. € Inlets should be inspected weekly at a minimum and daily during storm events. All storm drain inlets will be monitored for sediment intrusion regularly. As needed, storm drains will be protected with filter fabric to prevent sediment from entering the system (BMP C220). IELEMENT 8: Stabilize Channels and Outlets € Design, construct, and stabilize all on-site conveyance channels to prevent erosion from the following expected peak flows: o *Channels must handle same peak volumetric flow rate as temporary pipe slope drains listed in Element 6, above. € Provide stabilization, including armoring material, adequate to prevent erosion of outlets, adjacent streambanks, slopes, and downstream reaches at the outlets of all conveyance systems. € The best method for stabilizing channels is to completely line the channel with a blanket product first, then add check dams as necessary to function as an anchor and to slow the flow of water. There are no conveyance channels or outlets on the site. ELEMENT 9: Control Pollutants € Design, install, implement, and maintain effective pollution prevention measures to minimize the discharge of pollutants. € Handle and dispose of all pollutants, including waste materials and demolition debris that occur on-site in a manner that does not cause contamination of stormwater. € Provide cover, containment, and protection from vandalism for all chemicals, liquid products, petroleum products, and other materials that have the potential to pose a threat to human health or the environment. On-site fueling tanks must include secondary containment. Secondary containment means placing tanks or containers within an impervious structure capable of containing 110% of the volume contained in the largest tank within the containment structure. Double-walled tanks do not require additional secondary containment. € Conduct maintenance, fueling, and repair of heavy equipment and vehicles using spill prevention and control measures. Clean contaminated surfaces immediately following any spill incident. € Discharge wheel wash or tire bath wastewater to a separate on-site treatment system that prevents discharge to surface water, such as closed-loop recirculation or upland land application, or to the Version Date: February 20, 2019 sanitary sewer, with local sewer district approval. Wheel wash or tire bath wastewater should not include wastewater from concrete washout areas. € Apply fertilizers and pesticides in a manner and at application rates that will not result in loss of chemical to stormwater runoff. Follow manufacturers' label requirements for application rates and procedures. € Use BMPs to prevent contamination of stormwater runoff by pH-modifying sources. The sources for this contamination include, but are not limited to: bulk cement, cement kiln dust, fly ash, new concrete washing and curing waters, waste streams generated from concrete grinding and sawing, exposed aggregate processes, dewatering concrete vaults, concrete pumping, and mixer washout waters. Adjust the pH of stormwater if necessary to prevent violations of the water quality standards. € Assure that washout of concrete trucks is performed off-site or in designated concrete washout areas only. Do not wash out concrete trucks onto the ground, or into storm drains, open ditches, streets, or streams. Do not dump excess concrete on site, except in designated concrete washout areas. Concrete spillage or concrete discharge to surface waters of the State is prohibited. Do not use upland land applications for discharging wastewater from concrete washout areas. € Obtain written approval from Ecology and provide to the City before using chemical treatment other than CO2 or dry ice to adjust pH. € Woody debris may be chopped and spread on site. € Conduct oil changes, hydraulic system drain down, solvent and de-greasing cleaning operations, fuel tank drain down and removal, and other activities which may result in discharge or spillage of pollutants to the ground or into stormwater runoff using spill prevention measures, such as drip pans. € Clean contaminated surfaces immediately following any discharge or spill incident. Emergency repairs may be performed on-site using temporary plastic placed beneath and, if raining, over the vehicle. The only anticipated pollution on the site will be from washout of concrete trucks. A designated concrete washout area, designed to capture concrete washout, will be provided (BMP C151; BMP C154). No oil changes, vehicle maintenance, refueling, etc. will be permitted on the site. A spill prevention kit will be kept onsite. Any chemical or liquid product (i.e, paint) stored on site will be covered and securely protected (BMP C153). ELEMENT 10: Control De-Watering € Discharge foundation, vault, and trench dewatering water, which have characteristics similar to stormwater runoff at the site, into a controlled conveyance system before discharge to a sediment trap or sediment pond. € Discharge clean, non-turbid de-watering water, such as well-point ground water, to systems tributary to, or directly into surface waters of the State, as specified in Element 8, provided the de-watering flow does not cause erosion or flooding of receiving waters or interfere with the operation of the system. Do not route clean dewatering water through stormwater sediment ponds. Note that"surface waters of the State" may exist on a construction site as well as off site; for example, a creek running through a site. € Handle highly turbid or contaminated dewatering water separately from stormwater. € Other treatment or disposal options may include: 1. Infiltration 2. Transport off-site in a vehicle, such as a vacuum flush truck, for legal disposal in a manner that does not pollute state waters. 3. Ecology-approved on-site chemical treatment or other suitable treatment technologies. 4. Sanitary or combined sewer discharge with local sewer district approval, if there is no other option. 5. Use of a sedimentation bag with outfall to a ditch or swale for small volumes of localized dewatering. € Construction equipment operation, clamshell digging, concrete tremie pour, or work inside a cofferdam can create highly turbid or contaminated dewatering water. € Discharging sediment-laden (muddy) water into waters of the State likely constitutes a violation of water quality standards for turbidity. The easiest way to avoid discharging muddy water is through infiltration and preserving vegetation. Version Date: February 20, 2019 There will be no de-watering activities as part of this project. Groundwater level is below the lowest footing excavation. ELEMENT 11: Maintain BMPs € Maintain and repair all temporary and permanent erosion and sediment control BMPs as needed to assure continued performance of their intended function in accordance with BMP specifications. € Remove all temporary erosion and sediment control BMPs within 30 days after achieving final site stabilization or after the temporary BMPs are no longer needed. Some temporary erosion and sediment control BMPs are bio-degradable and designed to remain in place following construction such as compost socks. € Provide protection to all BMPs installed for the permanent control of stormwater from sediment and compaction. All BMPs that are to remain in place following completion of construction shall be examined and placed in full operating conditions. If sediment enters the BMPs during construction, it shall be removed and the facility shall be returned to the conditions specified in the construction documents. € Remove or stabilize trapped sediment on site. Permanently stabilize disturbed soil resulting from removal of BMPs or vegetation. All BMP's shall be monitored and maintained/repaired as needed for the duration of construction. Any sediment that accumulates on site or enters BMP's will be removed as needed. to E uj aRmsro•-•114-16 12, &14-3 '1D$z, w.crtcD k�t. IbM� lat-A C T `�1`- ELEMENT 12: Manage the Project— Projects subject to Minimum Requirements 1-9 must have a Certified Erosion and Sediment Control Lead (CESCL) for site inspections. Projects subject to Minimum Requirements 1-5 do not require the inspector to be certified. By the initiation of construction, the SWPPP must identify the CESCL or inspector, who shall be present on-site or on-call at all times. € Phase development projects to the maximum degree practicable and take into account seasonal work limits to prevent soil erosion and prevent transporting sediment from the site during construction. € Inspection and monitoring — Inspect, maintain, and repair all BMPs as needed to assure continued performance of their intended function. € Maintain, update, and implement the SWPPP. € Clearing and grading activities for developments shall be permitted only if conducted using an approved site development plan (e.g., subdivision approval). € From Oct 1 through Apr 30, clearing, grading, and other soil disturbing activities is permitted only if shown that the site operator will prevent silt-laden runoff from leaving the site through a combination of the following: 1. Site conditions including existing vegetative coverage, slope, soil type, and proximity to receiving waters. 2. Limit activities and the extent of disturbed areas. 3. Proposed erosion and sediment control measures. Weather conditions can influence the seasonal limitation on site disturbance. The City of Anacortes has the authority to take enforcement action per AMC 19.76 Stormwater. € The following activities are exempt from the seasonal clearing and grading limitations: 1. Routine maintenance and necessary repair of erosion and sediment control BMPs; 2. Routine maintenance of public facilities or existing utility structures that do not expose the soil or result in the removal of the vegetative cover to soil 3. Activities where there is 100% infiltration of surface water runoff within the site in approved and installed erosion and sediment control facilities. This project is subject to Minimum Requirements 1-5; no CESCL required. ELEMENT 13: Protect Low Impact Development BMPS Version Date: February 20, 2019 € If implementing any bioretention facilities or rain gardens, refer to the applicable BMP sections of the Manual for requirements. The area of the site where the rain garden will be located will not be in the way of heavy construction equipment, however care will be taken to monitor the area regardless (BMP C102). After the rain garden is finished high visibility fence (BMP C103) will be erected around it as a precaution. The rain garden will be monitored for performance and function regularly, and corrective action taken as needed. Applicant Signature Date TAB 3 (MINIMUM REQUIREMENT#3) • 1-2.5.3 Minimum Requirement#3— Source Control of Pollution All known, available and reasonable source control BMP's must be applied to all projects. Source control BMP's must be selected, designed, maintained according to the reference Ecology Manual. The intent of source control BMP's is to prevent stormwater from coming in contact with pollutants. They are a cost-effective means of reducing pollutants in stormwater, and, therefore, should be considered in all projects. There are no source points of pollution on the site. Version Date: February 20, 2019 TAB 4(MINIMUM REQUIREMENT#4) • Minimum Requirement#4— Preservation of Natural Drainage Systems and Outfalls Natural drainage patterns shall be maintained and discharges from the project shall occur at the natural location, to maximum extent practicable. The manner by which runoff is discharged from the project site must not cause a significant adverse impact to downstream receiving waters and down gradient properties. All outfalls require energy dissipation. The objective is to preserve and utilize drainage systems to the fullest extent because of the multiple stormwater benefits these systems provide; and to prevent erosion at the downstream of the discharge location. Refer to the reference manual for supplemental guidelines and additional information under this section. There are no natural drainage systems or outfalls on the site. Version Date: February 20, 2019 TAB 5 (MINIMUM REQUIREMLN'r ) • Minimum Requirement#5-OUP-sire Stormwater Management 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. Is this project Flow Control Exempt? YES (Yes\No) (See Appendix l-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). There are no streams, or erosion problems on the site or adjacent to the site. The site is in a fully developed urban area. mR -re\PDg- S9 € .,‘t-J All sites are required to utilize BMP T5.13- Post Construction Soil Quality and Depth. For each surface, consider the BMP's 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. Feasiblity shall be determined by evaluation against: 1. Design criteria, limitations and infeasiblity criteria identified for each BMP in this manual, and; 2. Competing needs criteria listed in Chapter V-5-On-site Stormwater Management. Lawn and Landscaped Area: • BMP T5.13: Post-Construction Soil Quality and Depth. (Attach Detail in Report) Refer to this site for requirements and specifications. All projects are required to utilize this BMP. http://www.soilsforsalmon.org/pdf/Soil BMP Manual.pdf See below for the"Model Soil Management Plan for BMP T5.13" to be submitted with Drainage Report and Application Material. Version Date: February 20, 2019 Date: Inspector: Approved: Revisions Required: Roofs: (Provide feasible detail and maintenance and operations specifications in the report) 1. BMP T5.30: Full Dispersion Feasible\Infeasible If infeasible, explain the criteria: - Infeasible, due to lack of loam soils on site and insufficient space for full dispersion. /Or, T5.10A: Downspout Full Infiltration Feasible\Infeasible If infeasible, explain the criteria: BMP T5.14A: Rain Gardens Feasible\Infeasible If infeasible, explain the criteria: Downspout full infiltration; Infeasible, due to soil permeability and due to lack of space for infiltration trenches. Rain garden; feasible, included on plan. Or, BMP T7.30: Bioretention Cells, Swales, and Planter Boxes Feasible\Infeasible If infeasible, explain the criteria: 2. BMP T5.10B: Downspout Dispersion Systems Feasible\Infeasible If infeasible, explain the criteria: Infeasible; due to lack of space. 3. BMP T5.10C: Perforated Stub-out Connections Feasible\Infeasible If infeasible, explain the criteria: Infeasible; lot is flat and on-site downspout dispersal would result in saturated yard. Other Hard Surfaces: (Provide feasible detail and maintenance and operations specifications in the report) 1. BMP T.5.30 Full Dispersion Feasible\Infeasible If infeasible, explain the criteria: Infeasible; due to lack of soil permeability and due to lack of space. Version Date: February 20, 2019 2. BMP T5.15: Permeable Pavements Feasible\Infeasible If infeasible, explain the criteria: Infeasible; driveway and parking space are both accessed from a gravel alley at south side of lot. Vehicle tire tracking of gravel fines and sediment onto the pavement is inevitable and would render permeable pavement useless. Or, BMP T.14.A: Rain Gardens Feasible\Infeasible If infeasible, explain the criteria: Feasible; included on plan. Or, BMP T7.30: Biorention Cells, Swales and Planter Boxes Feasible\Infeasible If infeasible, explain the criteria: 3. BMP T5.12: Sheet Flow Dispersion Feasible\Infeasible If infeasible, explain the criteria: Infeasible; due to lack of space and no slope. Or, BMP T5.11: Concentrated Flow Dispersion Feasible\Infeasiible If infeasible, explain the criteria: Infeasible; due to lack of space. If all BMP's have been declared infeasible to the project site, then the site is subject to Adjustments (Section 5) and ExceptionsNariances (Section 6) per the City's Phase II Municipal Stormwater Permit and the Anacortes Municipal Code, Section 19.76.040—Stormwater Management Manual, Item G —Adjustments and Exceptions. The review type is considered a Type 2 —Administrative Decision, requiring a 14-day comment period, per Table 19.20.030-1 — Review Classification and Process Matrix. See attached document. Applicant Signature Date City of 4,110W47 20, 2019 APPENDIX 1 —Survey performed by a Professional Land Surveyor Version Date: February 20, 2019 AUDITOR'S CERTIFICATE NM if,., 1 t`i IU IIJ . ail �O•::;z 8 L'1,.1 5 2 Skviee_irnty Auditor it,, 'y. 915I3,00 7/2Ix?01 X:•Page I.of %, 1 3:41PM AT REQUEST 0 SEMRAU E GIN:"'E#'ING ty,SU E'4WG 2:4'>.C:2�. RID CONC MON WITH l ,. �` FND CONC MON W11H PIN, DOWN 0.30'/N P/N, DOWN 0.30'/N 9 '= ? ' ", ''t*� CASE MARCH 2O17 CASE MARCH o'IN SKA IT COUN A ,T '•i l "DEPUTY 379.92' rrt 1�. i "-. 6TH STREET �`' ' ,,SIDEWALK •., F" '` _ _ — s a9'SB'33 E_299.90' ..-Z 3' _ •''NOTII S!:'`�r. "�a;. :i r'. . r- T 104.97' I. .97' �'` 7-89,9B'- %� a, 1• r , , , r�;- INUI�CA1c;S''SwJ 1/f;x18• REBAR WITH CAP - 'SEMRAU 28626" I' I I ' 1/2" IP WITH ,,. `�`•5 !ter tNDICP'1ES""SET LEAD TACK & SHINER - "SEMRAU 28626' PLUG & TACK I " �;, T�-',.. 40' T.6 .k O''�. INQICATEi:,,OoSTING REBAR OR IRON PIPE FOUND AS DESCRIBED. W I j �+ I `� I -' A W Im ,•'7,7 1,.,..r r4?.. ?q., B -9"';_IND PATES FOUND MONUMENT IN CASE AS DESCRIBED. �/ L. L 't- L. L / I ," d;. DEL, . o v 1' OVERHA G� HOUSE c�i ' "• .r'�•':t„1,`` t•� S.;,?. TI I D,l SCRIPTION FOR THIS SURVEY IS FROM STATUTORY WARRANTY DEED Ia I 7.26 ai'g °3I'� 0� �F' A �';1„ Ri:LTJ`RD UNDER AUDITOR'S FILE NO. 201412010114 DATED DECEMBER 1 2014. a_ VY fj °' l� i 3:'"`BASIS OF BEARING: EXISTING MONUMENTS FOUND IN THE CENTERLINE OF 6TH .24 Z !�. I I Z ;>, ;i STREET BETWEEN AVENUE M AND AVENUE N, BEARING = SOUTH 89'56'33" EAST. , �� v l'n 4 L t I ~_I44 :- , *, `'� j 4. ALL DISTANCES ARE SHOWN IN FEET. �= I 104.9B' ,' -_�-��i 104.95' _ �, �89.96'� _ 0' t`�, qO' i''\.�; 'I?�4' 5. INSTRUMENTATION: LEICA MSSD THEODOLITE DISTANCE METER. r` 1.0. 'S 89'57'OB' E 299.87' — m r J 6. SURVEY PROCEDURE: STANDARD FIELD TRAVERSE. g '� " 10' WOE GRAVEL ALLEY * 'ALE l' ! 7. THIS SURVEY WAS REQUESTED BY MICHAEL HUBER. $ 1k +•''� 8, THIS SURVEY MAY SHOW OCCUPATIONAL INDICATORS AS PER W.A.C. CHAPTER s �, 332.130. UNES OF OCCUPATION MAY INDICATE AREAS FOR POTENTIAL CLAIMS OF <-y " •,.. '4,4., 'j(, ��'. UNWRITTEN OWNERSHIP. THIS BOUNDARY SURVEY HAS ONLY SHOWN THE r`' I - °r' t`: RELATIONSHIP OF UNES OF OCCUPATION TO THE DEEDED UNES OF RECORD. NO w w '' ._t5 it I` �'• RESOLUTION OF OWNERSHIP BASED ON UNWRITTEN RIGHTS HAS BEEN MADE OR II.ET ,c,r l; IMPLIED BY THIS SURVEY. r:. Y ,;r` 9. EXCEPT AS SPECIFICALLY STATED OR SHOWN ON THIS SURVEY MAP. THIS •`` '�. tiy;' SURVEY DOES NOT PURPORT TO REFLECT ALL OF THE FOLLOWING WHICH MAY BE L'l',� '';,. I APPLICABLE TO THE SUBJECT REAL ESTATE: EASEMENTS, BUILDING SETBACKS UNES, RESTRICTIVE COVENANTS, SUBDIVISION RESTRICTIONS, ZONING OR OTHER x-. y; ";Y._ ?.".; LAND-USE REGULATIONS AND ANY OTHER FACTS THAT AN ACCURATE AND 'P:•{t�'+�v.r,.rtt. ^ it�t, '°:I � ;,: " ,, °' CURRENT TITLE SEARCH MAY DISCLOSE. L 'ti' .YI.. .-.• `ry=-—. _%. DESCRIPTION 7TH STREET 1, :, iStir(. ,;YF`}v„ J',f„ ` LOTS 4, 5, 6, AND THE EAST HALF OF LOT 7, BLOCK 74, MAP OF 7HE CITY of p ' j c,•? ANACORTES, ACCORDING TO THE PLAT THEREOF, RECORDED IN VOLUME 2 OF `. 'I•-' 5.11 '•1 do. PLATS, PAGE 4, RECORDS OF SKAGIT COUNTY, WASHINGTON, �,.�:,::,:�e::LE .I, :i `a' ti S 89'57' '3E 1,,oi't,.�,:o• I ,� `t, ''. �' , J 379 2'+a"— N1,..— �: ,�sT SITUATED IN SKAGIT COUNTY, WASHINGTON N-- FND CONC MON WITH "r' {; ; Ir: FND CONC MON WITH —ir • PIN, DOWN 0.30'IN .,�. ''S1':. Ors ' ';,•. I. ; j+ P/N DOWN 0.30 IN CASE MARCH 2017 ' ., ':ii, •A; +t, ,fir r¢ CASE MARCH 2017 i. iw,n 'r.. .. :f�'T 5'S, ,. oil •zt** \ "41.1, Id tf, 4 VICINITY MAP :W. ,5• 'V.. "I4,. .S. AlN.T.S. 14 i!, "Ili na ;vSU,R YQ ,'S�;:.;:CE TIF1CATE SHEET 1 OF 1 : `+ INS RAC"" RELY`LY`.5'EPRESENTS A SURVEY MADE BY ME OR UNDER MY DIRECTION IN ,i "'i'• COIVORtdANCB''"1411-,• T;E REQUIREMENTS OF THE SURVEY RECORDING ACT AT THE REQUEST _t1,.B.SE i, OF laCHAFL H E `i,' ' . of WA t a& ' SURVEY OF LOTS 4, 5, 6, Sc E 1/2 LOT 7, BLOCK 74, A. {'"''L N. "" '. SKAGIT COUNTY, SPA , ..y cI ' •.• MAP OF CITY OF ANACORTES, ':-.A.,... y1•4, "'`•I oHt1 B. SErARA P.E.. P.Ls., CERTIFICATE NO. 28626 DAME � •t� ; SE 1/4, SE 1/4, SECTION 13 T. 35 N., R. 1 E., W.M.µi• 'i aEMrtAU ENGINEERING & SURVEYING, P.LLC. '4 ANACORTES, WASHINGTON '`: . z; ;2118 RIVERSIDE DRIVE SUITE 208 .i\ '•x,,•;W MQJNT VERNON, WA 98273 po.;;:, zie:6 �o F',' AS' to� a FOR: MICHAEL HUBER ,, „PHONE 360-424-9566 �o1'AL LAltii9 r FB.275 PG. 57—X SEMRAU ENGINEERING & SURVEYING SCALE: 1"= 40' 4'•:'.•j1" ntl\1lSllyrr7fruvl� SURVEYING • ENGINEERING • PLANNING MERIDIAN: ASSUMED MOUNT VERNON, WA 98273 380-424-9566 JOB NO. . 5625 APPENDIX 2— Soils Anaylsis (Volume 1, Chapter 3.1.1) Version Date: February 20, 2019 �� f .j I s Vesting & Consulting, Inc. 111 Geotechnical Engineering•Materials Testing•Special Inspection•Environmental Consulting 111. - - • ruts Testing&Consul0 areng' January 10, 2019 Michael Huber, Owney/Developer 12814 127th Ave. SE. Snohomish, WA 98290 Mwhuber@mac.com (425)239-7333 Subject: Geotechnical Investigation and Engineering Report Proposed Residential Development 1211 61h Street, Anacortes, Washington 98221 MTC Project No.: 18B355 Dear Mr. Huber: This letter transmits our Geotechnical Engineering Investigation Report for the above-referenced project. Materials Testing & Consulting, Inc. (MTC) performed this geotechnical study in accordance with our Proposal for Geotechnical Services,dated November 7th, 2018. We would be pleased to continue our role as your geotechnical engineering consultants during the project planning and construction. We also have a keen interest in providing materials testing and special inspection during construction of this project. We will be pleased to meet with you at your convenience to discuss these services. We appreciate the opportunity to provide geotechnical services to you for this project. If you have any questions regarding this report, or if we can provide assistance with other aspects of the project, please contact us at(360) 755-1990. Respectfully Submitted, MATERIALS TESTING&CONSULTING,INC. John Gillaspy, L.E. Kevin Quillan, G.I.T. NW Region Geotechnical Division Manager Project Geologist Attachment: Geotechnical Investigation and Engineering Report Corporate • 777 Chrysler Drive • Burlington, WA 98233 • Phone 360.755.1990 • Fax 360.755.1980 SW Region • 2118 Black Lake Blvd. S.W.• Olympia, WA 98512 • Phone 360.534.9777 • Fax 360.534.9779 NW Region • 805 Dupont, Suite #5 • Bellingham, WA 98225 • Phone 360.647.6061 • Fax 360.647.8111 Kitsap Region • 5451 N.W. Newberry Hill Road, Suite 101 • Silverdale, WA 98383 • Phone/Fax 360.698.6787 Visit our website: www.mtc-inc.net GEOTECHNICAL INVESTIGATION AND ENGINEERING REPORT PROPOSED SINGLE-FAMILY RESIDENCE AND DETACHED GARAGE 1211 6TH STREET ANACORTES, WASHINGTON 98221 Michael Huber, Owner/Developer 12814 127th Ave. SE. Snohomish, WA 98290 Mwhuber@mac.com (425) 239-7333 Prepared by: oi Wash/ E;R e OpARtk>,,,, _ r PI <3\140019N •1011710y ed Ge° 1-10-19 %MA►, �. ,= 1-10-19 John R. Gillaspy John Gillaspy, L.E.G. Medhanie Tecle, P.E. NW Region Geotechnical Division Manager Engineering Manager Additional Work By: Kevin Quillan, G.LT. Project Geologist' MATERIALS TESTING & CONSULTING,INC. (MTC) 777 Chrysler Drive tl 'aka Burlington, Washington 98233 Phone: (360) 755-1990 1L Fax: (360) 755-1980 .+ L ,,Ill. 7�dte � — January 10, 2019 r�als Testing&Consulttn�1r MTC Project Number: 18B355 Copyright 2018 Materials Testing & Consulting, Inc. All Rights Reserved ii Huber Residence Geotechnical Report Materials Testing & Consulting, Inc. January 10 , 2019 Project No . : 18B355 Table of Contents 1 . 0 INTRODUCTION 1 1 . 1 GENERAL 1 1 .2 PROJECT DESCRIPTION 1 1 . 3 PURPOSE AND SCOPE OF SERVICES 2 2 . 0 SITE EXPLORATION AND LABORATORY TESTING 3 2 . 1 SITE EXPLORATION 3 2 .2 LABORATORY TESTING 3 3 . 0 EXISTING SITE CONDITIONS 4 3 . 1 SURFACE DESCRIPTION 4 3 .2 AREA GEOLOGY 4 3 . 3 SOIL CONDITIONS 5 3 .4 GROUNDWATER CONDITIONS 6 4 . 0 KEY GEOLOGIC CONSIDERATIONS 8 4 . 1 GENERAL SITE SOIL CONDITIONS 8 4 .2 SCOPE OF SITE GRADING 8 4 . 3 TEMPORARY EXCAVATION CUT SLOPES , SHORING, AND DEWATERING 9 5 . 0 DESIGN RECOMMENDATIONS 10 5 . 1 FOUNDATION FEASIBILITY 10 5 .2 FOUNDATION RECOMMENDATIONS 11 5 . 3 SLAB -ON-GRADE CONSTRUCTION 13 5 .4 RETAINING WALL DESIGN 15 5 . 5 SEISMIC DESIGN PARAMETERS AND LIQUEFACTION POTENTIAL 17 5 . 6 INFILTRATION RATE DETERMINATION 18 6 . 0 CONSTRUCTION RECOMMENDATIONS 21 6 . 1 EARTHWORK 21 6 . 1 . 1 Excavation 21 6 . 1 .2 Subgrade Evaluation and Preparation 21 6 . 1 . 3 Site Preparation, Erosion Control and Wet Weather Construction 21 6 .2 STRUCTURAL FILL MATERIALS AND COMPACTION 22 6 .2 . 1 Materials 22 6 .2 .2 Placement and Compaction 23 6 . 3 ' TEMPORARY EXCAVATIONS AND SLOPES 23 6 .4 PERMANENT SLOPES 24 6 . 5 UTILITY TRENCHES AND EXCAVATIONS 24 7 . 0 ADDITIONAL RECOMMENDED SERVICES 25 8 . 0 LIMITATIONS 26 Appendix A . SITE LOCATION AND VICINITY 27 Appendix B. EXPLORATION LOCATIONS 28 Appendix C. EXPLORATION LOGS 29 Appendix D. LABORATORY RESULTS 38 111 Huber Residence Geotechnical Report Materials Testing&Consulting,Inc. January 10,2019 Project No.: 18B355 1.0 INTRODUCTION 1.1 GENERAL This report presents the findings and recommendations of Materials Testing & Consulting, Inc.'s (MTC) geotechnical engineering study conducted for the design and construction of the proposed single-family residential development with associated detached garage. The subject site is located in the historical neighborhood of Anacortes, Washington along 6th Street. The site location, aerial photo overview, and proposed layout of the project site are presented in Figures 1 and 2 of Appendices A and B. 1.2 PROJECT DESCRIPTION The client intends to construct a large single-family residence and detached two-story garage within the previously developed residential site consisting of approximately 0.24 acres (Figure 2). The main residence will be constructed in the northeastern portion of the site and will consist of a crawl space at the southern end of the building with an underground basement level at the northern end of the structure with a retaining wall foundation. The two-story garage is proposed to be constructed at the southwestern corner of the site. The redevelopment will also require stormwater control improvements to service new impervious area, including on-site infiltration, if feasible. Currently, the client is considering the northwest and southeast corner of the site for construction of onsite infiltration facilities. The site is presently undeveloped and primarily unvegetated following demolition of the previous residence. Topography across the site is generally flat with slight undulations and a minor swale in the northwest corner of the lot. The northern end of the property consists of a 4.5 to 6.5-foot high moderately sloping hillside presumably constructed during previous roadway development and/or lot development in the early 1900's. The site is bounded by 6th Street to the north and two currently developed residential lots of similar size and character to the east and west. A moderate-sized church building is located to the southeast across an alleyway that boarders the southern edge of the site. MTC was provided with preliminary building plans and indicate that final grades will be approximately equal to present grades across the site. Construction is anticipated to consists of primarily of isolated column and perimeter footing members cut into present grades. Building design is assumed as relatively light wood-frame construction with slab-on-grade floors for the basement and detached garage. Projected loads are likely to be typical for the type and materials of construction, and no unusually large or vibratory loads are expected. MTC should be allowed to review the final plans and specifications for the project to ensure that the recommendations presented herein are appropriate. Recommendations and conclusions presented by this report will need to be re-evaluated in the event that changes to the proposed construction are made. 1 Huber Residence Geotechnical Report Materials Testing&Consulting,Inc. January 10,2019 Project No.: 18B355 1.3 PURPOSE AND SCOPE OF SERVICES The purpose of our study was to explore subsurface conditions at the site and provide geotechnical recommendations for design and construction of the proposed developments, including assessment of site infiltration feasibility and determination of design rates if applicable. Our scope of services was consistent with that presented in our Proposal for Services, dated November 7th, 2018. 2 Huber Residence Geotechnical Report Materials Testing&Consulting,Inc. January 10,2019 Project No.: 18B355 2.0 SITE EXPLORATION AND LABORATORY TESTING 2.1 SITE EXPLORATION Our site exploration activities were performed on December 14th, 2018. Activities involved observing excavation of four (4) machine-assisted test pits (TPs) in the vicinity of the proposed building site and potential stormwater facility areas. In addition, three (3) supplemental Dynamic Cone Penetrometer (DCP)tests were performed at representative locations near excavated test pits and at proposed building locations to help characterize in-situ soil strength conditions and provide foundation bearing recommendations. Subsurface exploration locations were selected by an MTC Project Geologist while on site to provide representative coverage for the proposed developments as possible at the time of the field visit. The relatively flat and unvegetated nature of the site provided for unhindered access to the test locations and provided sufficient access. All excavations were terminated upon reaching maximum equipment extent or planned termination depths at potential stormwater facility locations. All DCP tests were advanced until reaching practical refusal. Test pit TP-1 was excavated in the northwest corner of the site to the west of the proposed residence to assess soil for stormwater infiltration and was terminated at 6.0 feet below present grade (BPG). Test pit TP-2 was excavated at the NW corner of the proposed residence approximately 10 feet from the northern slope and was terminated at 7.0 feet PBG at maximum machine depth. Test pit TP-3 was excavated directly between the proposed residence and the detached garage approximately central to the site and was terminated at 7.0 feet BPG. Test pit TP-4 was excavated in the southeast corner of the site directly south of the proposed residence to assess soil for stormwater infiltration and was terminated at 5.8 feet BPG. DCP-1 and DCP-2 were advanced at the northeast and southeast corners of the proposed residence, respectively. DCP-3 was advanced at directly north of the proposed garage along the southern footing line approximately central to the structure. DCP-1, DCP-2, and DCP-3 reached practical refusal at 4.8, 6.5, and 5.0 feet BPG, respectively. All test pit and DCP locations are shown on the site map in Appendix B, Figure 2, overlain on current provided site plans for the proposed developments. Exploration locations are approximate, as based on hand-measurements and existing references noted at the time of the field work. Additional information regarding test pits and DCP exploration logs can be found in Appendix C of this report. 2.2 LABORATORY TESTING Laboratory tests were performed on selected soil samples in accordance with ASTM standards to determine index and engineering properties of the site soils. Tests included supplementary soil classification and grain-size distribution analysis predominantly for stormwater infiltration assessment. Laboratory test results are presented on the test reports included in Appendix D. 3 Huber Residence Geotechnical Report Materials Testing&Consulting,Inc. January 10,2019 Project No.: 18B355 3.0 EXISTING SITE CONDITIONS 3.1 SURFACE DESCRIPTION The proposed redevelopment is located on a single,previously developed parcel located in the historical district of Anacortes along 6th Street. Development surrounding the site is generally single-family residences of similar size and style as the proposed redevelopment. The site is bounded by 6th Street to the north and an alleyway to the south where site access is granted. Currently occupied residences are located to the west and east of the site as well as across 6th Street to the north. Across the alley to the south is another residence and two large wooden church buildings. Topography across the relatively unvegetated site is generally level with a dominant slope rising upward towards the south from 6th street below. The site generally has a very slight northwest dipping slope with a small swale located in the northwest corner of the site at test pit TP-1's location. The dominant slope at the north end of the property is moderately north-dipping and accommodates approximately 4.5 to 6 feet of elevation between 6th Street and the overall site elevation. Vegetation on the site consists of well-kept grass with small deciduous trees located sparsely along the east and west site boundaries. 3.2 AREA GEOLOGY The Washington Geologic Information Portal published by the Washington State Department of Natural Recourses (DNR) indicates the project site is located in an area that consists of Deming Sand as part of the Everson Glaciomarine Drift(Qgdm). This unit is described as having clayey silt, silty clay, clay, and clay-rich diamicton and locally contains lenses and layers of sandy or gravelly outwash. This unit is commonly subdivided into Diamicton containing mostly silty sandy clay with scattered gravel (dropstones) or clayey silty sandy gravel. The Washington Depatttiient of Natural Resources (DNR) Interactive Map indicates the unit to be extensive in the areas surrounding the site. Shallow soils are mapped by the USDA NRCS Web Soil Survey as Clallam-Urban Land Complex, with 0 to 8 percent slopes. Clallam-Urban Land Complex is mapped typically on hillslopes with the parent material being glacial drift. A typical soil profile consists of 11 inches of gravelly ashy loam overlying very gravelly loam that extends to 27 inches with very gravelly sandy loam extending to approximately 60 inches. It is a member of Hydrologic Soil Group C with a very low to moderately low capacity to transmit water. The depth to restrictive features is more than 80 inches although depth to densic material is listed as 20 to 40 inches. Soil conditions consisting of sandy silts to silty sands with generally shallow depths to dense material were broadly consistent with geologic and soil map resources, although significant variations were observed locally due to fill deposits related to previous development. 4 Huber Residence Geotechnical Report Materials Testing&Consulting,Inc. January 10,2019 Project No.: 18B355 3.3 SOIL CONDITIONS A general characterization of on-site soil units encountered during our exploration is presented below. The exploration logs in Appendix C present details of soils encountered at each exploration location. The on-site soils are generally characterized as follows in stratigraphic order to depth: • Topsoil—Organic Silty Sand with Gravel, Silty Sand (OL-SM): Topsoil was observed at the surface at all test pit locations and were typically encountered as silty sands with gravel and locally silty sand having high organic content and being dark-brown in color. Topsoil deposits ranged from 0.9 to 1.3 feet thick and were occasionally found in loose and damp conditions. Trace trash refuse and charcoal indicated some degree of mixing during previous development and landscaping. • Historic Fill—Sand, Silty Sand to Sandy Silt(SW,ML-SM) Uncontrolled fill was observed in test pits TP-2 and TP-3 to extend to 3.6 and 3.7 feet BPG, respectively. Historic fill soils were found in loose to medium dense and damp conditions and were generally medium brown. These soils were interpreted as fill due to the presence of trace trash refuse scattered within the deposit, the presence of large charcoal seams at depths unreasonable for fires, and due to the presence of large (-1' dia. Cobbles) being encountered at depth. • Fine Subsoils—Silty Sand (SM): Fine-grained sandy subsoils consisting silty sands with clay were encountered in test pit TP-1 between 0.9 and 3.5 feet BPG. These soils were found in medium dense and damp to moist conditions. The fine subsoils were light brown to orange-brown with moderate oxidation staining was present throughout the horizon. Roots were present in the upper portion of the horizon. • Coarse Subsoils—Gravel(GW-GM): Coarse-grained gravely subsoils consisting of well-graded gravels with silt and sand were encountered in test pit TP-4 from 1.3 to 3.3 feet BPG. These soils were found in loose to medium dense and damp to wet conditions. The coarse-grained subsoils were generally stained to a reddish-brown throughout the horizon. • Glacial Drift—Silty Sand, Sandy Silt, and Sand with Silt(SM,ML, SW): Present at the base of all excavations were glacial drift soils consisting of silty sands, sandy silty, and sands with silt. These native soils extended from 3.3 to 3.7 feet BPG down to termination depths ranging from 5.8 to 7.0 feet BPG at planned depths. The sandy drift soils were found to be in medium dense to dense or hard conditions and were typically dry to damp. Some small pockets and lenses of more silt-rich soils were found with depth at all locations. Trace amounts of reddish oxidation staining was encountered at all locations with moderate mottling 5 Huber Residence Geotechnical Report Materials Testing&Consulting,Inc. January 10,2019 Project No.: 18B355 encountered in the upper 1.5 feet of the soil horizon in test pit TP-3 only. Generally, the soils were medium brown. Four DCP tests were advanced in close proximity to test pit locations at proposed footing locations to determine soil consistency and correlate data with soils observed in test pits. DCP-1 was advanced at the northeast corner of the main residence and indicated very loose to loose conditions extended to 4.5 feet BPG where soils became medium dense to very dense until termination at 4.9 feet BPG. DCP-2 was advanced at the southeastern corner of the main residence and indicated very loose to loose conditions extended to 2.0 feet BPG. Consistent medium dense conditions extended below to approximately 5.1 feet BPG where soils became progressively dense to very dense until termination at 6.5 feet BPG. Lastly, DCP-3 was advanced along the southern edge of the detached garage structure and indicated variable soil consistencies ranging from very loose to medium dense in the upper 4.0 feet BPG. Underlying the upper soils at DCP were generally dense soil conditions before termination on very dense soils at approximately 5.0 feet BPG. Results from DCP tests correlate well with the conditions observed in all four test pits with slightly variable soil conditions in the upper subsoils and/or fill deposits with conditions becoming firm at depths within the native glacial drift conditions. 3.4 GROUNDWATER CONDITIONS No surface water features were observed on site at the time of MTC's field visit. The nearest body of water is the Guemes Channel located approximately 300 feet to the north of the site. No seasonal channels or runoff zones were observed on the property during our field visit which was conducted during mid-winter season. Groundwater or seepage was not observed at any of the test pits excavated during MTC's visit. Moisture conditions were generally damp to moist and were considered dry at depth in the underlying glacial drift soils. The general lack of mottling within the lower glacial drift soils excepting the upper 1.5 feet of drift soils in test pit TP-3 may suggest that little water transmission occurs through these moderately to highly consolidated soils. Reddish oxidation staining was present within the fine- and coarse-grained subsoils present in test pits TP-1 and TP-4, respectively. The presence of rust-colored oxidation alteration along these horizons suggests that temporary perched water buildup or transient water flow occurs along this surface during rain events in the winter and shoulder seasons. No other mottling patterns were observed that would suggest perched water exists in shallow upper soils for prolonged spans of time. Therefore, we interpret the depth of restrictive conditions observed to correlate with the consolidated glacial drift soils conditions encountered at depths ranging from 3.3 to 3.7 feet BPG. Given the time of this investigation, during the mid-winter season following a generally dry week, it is likely that observed conditions represent a seasonally elevated but not necessarily peak condition of 6 Huber Residence Geotechnical Report Materials Testing&Consulting,Inc. January 10,2019 Project No.: 18B355 groundwater occurrence. The above discussion shall be understood to be an interpretation of peak seasonal conditions and is based on indirect evidence of soil color patterns and our past project experience. MTC's scope of investigation did not include determination or monitoring of seasonal groundwater elevation variations, conclusive measurement of groundwater elevations at the time of exploration, or deep explorations that may have encountered the regional groundwater table at greater depths past the extent of concern for the proposed construction. 7 Huber Residence Geotechnical Report Materials Testing&Consulting,Inc. January 10,2019 Project No.: 18B355 4.0 KEY GEOLOGIC CONSIDERATIONS This section discusses significant geotechnical issues that must be addressed in project planning and design. These considerations form the basis for the geotechnical engineering design recommendations presented in Section 5.0 and construction recommendations presented in Section 6.0. 4.1 GENERAL SITE SOIL CONDITIONS The results of MTC's surface and subsurface soils investigations indicate that the site is primarily underlain by a mix of fine- and course-grained sandy subsoils and/or variable fill deposits that overlie native glacial drift soils at all locations. Variable shallow soils consisting of topsoil, fill deposits, and fine- and coarse-grained sandy soils with an unknown depositional history are generally considered unsuitable for structural use and extend down to approximately 3.3 to 3.7 feet BPG. Fill soils were notably present in test pits excavated near the center of the site and extended down to 3.6 and 3.7 feet BPG in test pits TP-2 and TP-3, respectively. The loose and variable nature as well as the unknown depositional history of the fine- and coarse-grained shallow subsoils to the nearby uncontrolled fill suggest that these soils are inadequate for structural use beneath footings and slab on grade surfaces. An additional concern to the proposed redevelopment is the extent of previous development and the depth of disturbed soils caused by construction and removal of the previous residence. The following site preparation recommendations include a combination of overexcavation of the overlying unsuitably soft native and/or fill soils down to dense to very dense glacial till conditions below footing members. The site is considered to be generally feasible for onsite stormwater infiltration within the upper subsoils present at the potential stormwater facility locations. Presently, the northeastern and southwestern corners of the site will contain the residence and garage, leaving the northwestern and southeastern corners of the site available for stormwater infiltration. Soil conditions encountered at shallow depths in test pit TP-1 near the northwest corner of the site were generally fine-grained and are generally considered less feasible for infiltration than the shallow gravelly soils encountered in test pit TP-4 near the southeast corner of the site. The native soil conditions in test pits TP-1 and TP-4 were more closely assessed for stormwater infiltration potential via laboratory gradation testing and are discussed in Section 5.6. 4.2 SCOPE OF SITE GRADING A grading plan was not available to MTC at the time of this report. Based on discussions with the client, this study assumes finished exterior site grade will be approximately equal to current grade. Therefore, depths referred to in this report are considered roughly equivalent to fmal grade. 8 Huber Residence Geotechnical Report Materials Testing&Consulting,Inc. January 10,2019 Project No.: 18B355 5.6 INFILTRATION RATE DETERMINATION Gradation Analysis Method&Results During site explorations, MTC collected representative samples of soil horizons at shallow depths among potential infiltration strata at considered infiltration facility areas. Final infiltration facility location and depths were not specified prior to field work and soils were sampled from all excavation locations at representative soils horizon depths. Laboratory gradation analyses were completed including sieve tests for stormwater design characterization and rate determination to supplement field observations of select soil horizons. Results of laboratory testing in terms of rate calculation are summarized below. Laboratory results were interpreted to recommended hydraulic conductivity (Ksat) values in accordance with methods of the Washington State Department of Ecology Stormwater Management Manual for Western Washington (SMMWW), 2012/2014. Standard correction factors were applied as noted in the reference documents. Data and Ksat values are summarized in Table 3 below. Gradation results were applied to the Massmann (2003) equation (1) to calculate Ksat representing the initial saturated hydraulic conductivity, as described in the 2012 DOE SMMWW Volume III 3.3.6.3. (1) log10(Ksat) = -1.57 + 1.90*D10 + 0.015*D60 - 0.013*D90 - 2.08*ff Table 3 reports for each sample the input laboratory values and calculated Ksat. Corrected Ksat values presented below are a product of the initial Ksat and correction factor CFT. For a generalized design situation, we have applied a site variability factor of CFv = 0.33 due to the general variability of onsite soils, with typical values of CFt = 0.4 (for the Grain Size Method) and CFm = 0.9 (assuming standard influent control). (2) CFT=CFv x CFt x CFm= 0.33 x 0.4 x 0.9=0.12 Table 3. Results of Massmann Analysis TP # Depth USCS D10 D60 D90 Ff Ksat Corrected Ksat (BPG) (%) (inches/hour) (inches/hour) 1 2.5 SM 0.013 0.066 0.305 57.0 2.62 0.31 1.8 GW-GM 0.138 24.59 66.48 8.6 14.77 1.77 18 Huber Residence Geotechnical Report Materials Testing& Consulting,Inc. January 10,2019 Project No.: 18B355 Facility Design Rates and Discussion MTC understands the project stormwater system will undergo design pending the results of this study to confirm general feasibility, design parameters, and depth to groundwater or restrictive soil features influencing design. No design information was available at the time of this report. Assumptions of usable areas are based on our experience with past residential projects, and the provided layout of the reconstruction features. The areas presently considered for onsite stormwater infiltration include the northwestern and southeastern corners of the site where open areas will remain and infiltration facilities and pervious pavement would be considered. Soil conditions at test pit TP-1 in the northwestern corner of the site include shallow topsoil overlying approximately 2.6 feet of fine-grained subsoils with moderately to highly consolidated glacial drift soils encountered below. Soil conditions at test pit TP-4 in the southeast corner of the site include shallow topsoil overlying approximately 2.0 feet of coarse- grained subsoils with similarly consolidated glacial drift conditions below. Due to the infeasibility of infiltrating within the underlying consolidated silty sand to sandy silt glacial drift soils at deeper depths, soils within the fine- and coarse-grained subsoils were sampled for MTC's infiltration analysis. Soil samples analyzed included soils taken at 2.5 feet BPG in TP-1 and at 1.8 feet BPG in TP-4. Grain Size analysis methods based on SMMWW 2012/2014 standard calculation criteria yielded Corrected Ksat values ranging from about 0.31 to 1.77 inches per hour corresponding to the fine- and coarse-grained shallow subsoils found beneath topsoils, respectively. Due to the variable nature and contrasting infiltration capacities of the fine- and coarse-grained soils encountered at similar depths in test pits TP-1 and TP-4, two relatively conservative design rates have been provided for facilities designed in the vicinity of each test pit. Therefore, for the design of shallow infiltration facilities near TP-1, we recommend a maximum design Ksat value of 0.3 inches/hour, representing the fine-grained silty sands with clays encountered at shallow depths in the northwest corner of the site near test pit TP-1. Additionally, we recommend a maximum design Ksat value of 1.7 inches/hour, representing the coarse- grained well-graded gravels with silt and sand encountered at shallow depths in the southeastern corner of the site near test pit TP-4. These upper soils are not interpreted to be consolidated or compacted by glacial processes based on in-situ strength, and are considered eligible for rate determination via grain size analysis to be used at the discretion of the civil engineer. MTC considers the underlying glacial till conditions to be restrictive conditions in regard to the design and performance of an stormwater infiltration facility located on the subject site. Restrictive glacial drift conditions were encountered between 3.3 to 3.7 feet BPG across the site leaving approximately 2.5 feet and 2.0 feet of infiltratable subsoils below the overlying topsoils available for infiltationg the onsite stormwater load. Under this scenario, a 1-foot minimum separation between facility bases and restrictive conditions are maintained and is considered suitable for small-scale bioretention or roof downspout systems. 19 Huber Residence Geotechnical Report - Materials Testing&Consulting,Inc. January 10,2019 Project No.: 18B355 The fmal feasibility of infiltration facilities for the project and site, with respect to other development aspects, should be evaluated by the designer. The facility designer should also review the assumed correction factors per reference literature to ensure applicability with the proposed development, level of anticipated controls, and long-term maintenance plan. The designer may make reasonable adjustments to correction factors and the resulting design values based on these criteria to ensure design and operational intent is met. Use of the above rate for final design should take into account the noted limiting site factors, soil variability encountered, and depth to restrictive strata from the planned facility base. The project may be eligible for an increase in design rate if Pilot Infiltration Testing (PIT) methods are conducted, which is considered generally more reliable as a confirmation of actual field conditions and therefore can be applied less conservatively. In this case, PIT methods should be used once a facility location and depth is selected. PIT methods may also be required by the local municipality for final design approval depending on the style of design utilized. 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T t—H • /� NI,II Ir I I: I I ; 7 (ji; L.r i , ,. ., .r CID /�1 0 7C APPENDIX 3— Model Soil Management Plan for BMP T5.13 Note: Document is provided under Minimum Requirement 5 in this document Version Date: February 20, 2019 PROJECT INFORMATION "Model Soil Management Plan for BMP T5.13" age# of pages Complete all information on page 1; only site address and permit number on addition j ages_ 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 this plan) 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(required 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 AMENDMENT 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/ 1,000 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 --> —*-4—>—> QUANTITY: CU.YDS. TOTAL AMENDMENT/TOPSOIL/Ili ULCH FOR ALL AREAS(complete on page 1 only, totaling 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"(yes/no) ❑ Product#2: ❑Quantity: cu.yds. ❑ Test Results: %organic matter C:N ratio<25:1(except mulch,or<35:1 for native plants) "stable"(yes/no) ❑ Product#3: ❑Quantity: cu.yds. ❑ Test Results: % organic matter C:N ratio<25:1(except mulch,or<35:1 for native plants) "stable" (yes/no) Date: Inspector: Approved: Revisions Required: Version Date: February 20, 2019 APPENDIX 4— Determining Construction Site Sediment Damage Potential (Appendix 7— NPDES Phase II Permit) Note: See attached Version Date: February 20, 2019 Western Washington Phase II Stormwater Permit 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. 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; iv. 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, 20 Potential Page 1 of.3 Version Date: February 20, 2019 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 3100 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- 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 19(4) 500 — 5 , 000 cubic yards 5 > 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 soil group A 0 Hydrologic soil group B 0 Hydrologic soil group C 0 Hydrologic soil group D 40 E . Erosion Potential of predominant soils ( Unified Classification System ) : GW, GP , SW, SP soils 0 Dual classifications (GWGMjtr.QPGMt GW-GC , GP-GC , SW-SM , SW-SC , SP-SM , SP-SC) 1 GM GC , SM , SC soils ML , CL , MH , CH soils 40 F . Surface or Groundwater entering site identified and intercepted 1 . Yes 0 No 25 G . Depth of cut or height of fill > 10 feet : Yes 25 No C ) H . Clearing and grading will occur in the wet season (October 1 — May 1 ) : Yes 50 No 0 TOTAL POINTS 7 0 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) (),.Iq-lei APPENDIX 6- Documented Site Photos (Show all directions of the site, including frontage) (Insert Photo Here) Location: Ai, 1 l (oi Description of the photo: Photo taken by: in r +' �Y � l!1 ....�.. r �I �1.1 �1 � p r i Tr • I ' 1 � 1 ilit .r tll _ I xkfi`C', ! , }, t , jog 1 , r ',r 1 , , II fr PI , . 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' _ S g�)' S rpy '� • ?`(. 1. '� I 0 •t . # killk '44:11, v.to,401. 1. , 4 I INC • • • , . Ilk, . III • ot � ` Yr4' ill1 5. •. .4 APPENDIX 7— Drainage BMP Facility Maintenance Covenant Note: To be recorded prior to: 1) Temporary Certificate of Occupancy; 2) Final Certificate of Occupancy, and or; 3) Final Acceptance of the project. The attached document is in draft form. The applicant should work with the the City of Anacortes Engineering on obtaining a final copy before recording.