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HomeMy WebLinkAboutPermit File 2202 15th Street (3) Ravnik & Associates, Inc ,.,. /1, CIVII, ENGINEERING 8�T LAND-USE PLANNI �, �w �t4o STORM DRAINAGE MEMO 2,011 for �, \ • apt , NOV 0 220215 Street (BLD-2017 0349) jbtiAL LANDED GENTRY HOMES RESIDENTIAL DEVELOPM} Revised: October 26, 2017 September 29, 2017 The residential development proposed herein located at 2202 15th Street in Anacortes, Washington is generally proposed to include construction of a new house and driveway which will create an increase in the stormwater runoff from the site. The new roof area (3,376 sf), driveway (1,190 sf), and new sidewalk (470 sf) for a total of 5,036 sf of new impervious surfaces on a 10,475 square foot lot where an existing building, gravel and lawn areas currently exist. Stormwater runoff from the proposed 3,376 sf house roof area will be collected by downspouts and conveyed via a tight-lined system to a proposed infiltration trench to be installed within the northerly area of the lot. The driveway will be cross-sloped downhill to the west to promote dispersion and infiltration of runoff waters onto adjoining lawn areas which area large enough to infiltrate up to the 100-year storm as noted further on within this report. The sidewalk with collect runoff via a new gutter and convey it east, then north along the west side of"D" Avenue where it will enter an existing catch basin, as generally occurs today. Additional small areas of impervious surfaces, such as walkways, etc will be graded to disperse runoff via sheet flow onto adjoining areas of lawn/landscaping. Initially the DOE Flow Chart 1-2.4.1 Flow Chart for Determining Requirements for New Development has been used to determine that all minimum requirements apply to the new and replaced hard surfaces and converted vegetation areas. Most notably are Minimum Requirements #5-Onsite Stormwater Control, #6-Runoff Treatment, &#7-Flow Control. This project proposes to infiltrate runoff generated from a majority of the new and replaced hard surfaces as noted within the following sections of this report. Since the design within this report notes impervious surfaces (with the exception of the sidewalk) will be infiltrated as confirmed by use of a continuous model software (WWHM)they are considered "ineffective impervious surfaces", and thereby is Flow Control exempt per DOE Volume I Section I-2.5.7. As required by the 2014 Department of Ecology Stormwater Manual, the Western Washington Hydrology Model(WWII),a continuous model software, has been used to calculate pre-developed runoff conditions, post-developed runoff conditions, and the combined performance of storage volume and infiltration discharge. As further described herein, a underground detention/infiltration facility will be used to infiltrate the runoff from the new house. When sizing infiltration trenches using WWHM software, a theoretical riser outlet structure is purposely included within the analysis. If water is P:4Projects1170204DOCSDrainage Memo 10.26.17.doc 1 1633 LINDAMOOD LANE / P.O. BOX 361 • BURLINGTON, WA 98233 PH: (360) 707-2048 • FAx: (360) 707-2,216 found to be released through the riser structure,the volume of rainfall upon the developed site will be considered to have exceeded the system's infiltration and detention capacities, thereby identifying a failure in design. A properly designed and most efficient drainage system will use the infiltration and detention facilities to their maximum capacities without noting any water released through the theoretical riser used in the model. WWHM also be used to estimate 100-year runoff rates generated from the new driveway area in order to determine how much area will be needed to infiltrate 100% of these waters. Using WWHM three models were created to demonstrate the performance of the (1) Infiltration trench to infiltrate roof runoff, (2) Determine the necessary area required to infiltrate runoff from the proposed driveway area, and (3) Determine the runoff rates generated from the 470 sf of new sidewalk proposed along the project frontage. House Basin: Using an infiltration rate of 6.33 inches per hour as allowed within the attached geotechnical report prepared by Geotest for this project, it has been determined that it will take 46 if of 2-foot wide x 2-feet deep infiltration trench having a bottom elevation set at 3-feet below surface is necessary to infiltrate 100% of the post-developed runoff waters generated from the new 3,376 sf(0.77-ac) house roof area. As noted within the WWHM view information provided with this memo for the House it is noted that 0 cfs is released via the riser used in the modeling, indicating 100%infiltration has been achieved using the proposed trench. Refer to WWM I view and Report for the House attached with this memo for more detailed analysis information. Proposed Infiltration Trench(tight-lined to downspouts): 46'long x 2' deep x 2' deep Drainrock filled trench(bottom @ 3-feet below ex. grade) Void Ratio: 0.33 Infiltration: 6.33 in/hr(per the geotechnical report prepared by Geotest dated 08/30/17) Since the approved runoff model methods note that the entire runoff file is infiltrated up though the 100-year storm, the house is considered to be "ineffective" per (per the definition of"Effective Impervious Surface"(DOE Manual Volume I-Appendix G). The attached Memo prepared by Geotest Engineers notes that the proposed infiltration trench is extremely unlikely to negatively impact any surrounding foundations at its proposed location 11-feet from the north property line. Driveway Basin: As an alternative way to look at the driveway dispersion/infiltration provided, the use of WWHM allows us to calculate the 100-year flow frequency runoff that will be generated from the 1,190 sf(0.028 acre) of driveway area to be dispersed. Based on this analysis the 100-year storm event runoff values increase from 0.0016 cfs during the predeveloped (forest) condition up to 0.0171 cfs for the post developed (concrete) condition. This 0.0155 cfs increase in runoff that is anticipated from the conversion of 0.028 acres from forested condition to concrete driveway can easily be infiltrated onto the undeveloped P:lProjectsl170201DOCStDrainage Memo 10.26.17.doe 2 landscape area located to the west of the proposed driveway. Using a 1.50 in/hr infiltration rate from the attached geotechnical report prepared by Geotest, it only will take approximately 493 sf of area to infiltrate the 100-year storm even in an area where there is over 1,200 sf of area available. Refer to the following equations: Infiltration Rate Use 1.50 inch/hour =0.0250 inch/min =0.0000347 fps Required Infiltration Area for 0.028 ac driveway for 100-year storm 0.0171 cfs/0.0000347 fps = 493 square feet of area required to infiltrate the runoff from the developed 100-year storm event for the entire driveway area. Since the length of driveway is approximately 40 feet, it is estimated that it will take approximately 12.31 feet of width of vegetation and/or undisturbed soil along the west side of the driveway to infiltrate runoff from the 100-year storm. Based on the driveway length of 40 feet, full infiltration will be achieved in 12.31 feet. As with the roof runoff, since WWHM analysis (an approved continuous runoff modeling method) indicates that entire runoff file is infiltrated up though the 100-year storm, the house is considered to be "ineffective" per (per the definition of "Effective Impervious Surface". Sidewalk Basin: To estimate the 100-year flow frequency runoff that will be generated from the 470 sf (0.011 acre) of new sidewalk area WWHM will be used. Based on this analysis the 100- year storm event runoff values increase from 0.0006 cfs during the predeveloped (forest) condition up to 0.0067 cfs for the post developed (concrete) condition. Therefore there is only a 0.0061 cfs increase in runoff anticipated from the conversion of 0.011 acres from forested condition to concrete sidewalk. This area is considered Non-Pollution Generating Impervious surface (NPGIS). This surface is classified as "effective impervious surface" per the DOE manual. This new sidewalk area will be sloped to direct flows to the adjoining gutter which will convey waters easterly, then northerly to the existing catch basin structure located near the subject properties northeast corner. This small increase in "effective impervious surface" generated with this project will not have a significant impact on the existing drainage system and is noted as exempt from Runoff Control as noted within the summery section of this report. Summary For the proposed roof area, based on the areas previously noted, tight-lining roof downspouts to a 46-foot long x 2-foot-wide x 2-feet-deep drainrock filled infiltration trench and dispersing driveway runoff onto areas with vegetated flow path length greater than 12.31-feet is sufficient to mitigate the increase in stormwater runoff that will be P:1Projects1170201DOCSlDrainage Memo 10,26.17.doc 3 created by the construction of this new house. Both of these new impervious surfaces are considered ineffective per DOE definition of"Effective Impervious Surface" within the DOE Manual(Volume I-Appendix G). The new sidewalk along the existing roadway comprised of 470 sf of new concrete will be the only"effective" impervious surface proposed with this project. As previously determined using the WWHM analysis, the new roof area will be infiltrated and the new driveway area that will be dispersed and infiltrated makes these two impervious surfaces classified as "ineffective" per the DOE manual, leaving only the new roadside sidewalk. Accounting for the new roof area, driveway, and new roadside sidewalk, only increases the 100-year flow frequency runoff flows from 0.0065 cfs (0.0043 cfs + 0.0016 cfs + 0.0006 cfs) for the pre-developed to 0.0709 cfs (0.0471 cfs + 0.0171 cfs + 0.0067 cfs) during the post-developed condition. This shows there is only a 0.0644 cfs net increase in runoff during the 100-year flow frequency as estimated using the WWHM model, which is less than 0.10 cfs threshold, making this project exempt from DOE Requirement #7-Flow Control as noted in the following paragraph even when conservatively accounting for the ineffective impervious surfaces. Per DOE section 2.5.7-Minimum requirement #7-Flow Control a project is exempt from providing flow control is the project if: 1)The project has less than 10,000 square feet of effective impervious surfaces, 2) The project converts less than 3/4 acre of vegetation to lawn for landscape (or converts less than 2.5 acres of native vegetation to pasture), and 3) Through a combination of effective hard surface and converted vegetation areas cause less than. a 0.10 cubic feet per second increase in the 100-year flow frequency as estimated using the WWHM model. The analysis determining the difference in flow was conservatively performed using the forested land cover for the predeveloped condition as per the footnote in DOE Manual Volume I-Chapter 2 (page 65) states that the 0.10 cfs increase should be a comparison of the post project runoff to the existing conditions runoff based on the pre-project land cover, or the land cover that existing at the site as of a date when the local jurisdiction first adopted flow control requirements into code. Since this project has shown that proposed roof area is infiltrated and the driveway area has sufficient area to the west to infiltrate driveway runoff, based on the WWI-IM flow frequency values, means that these areas are technically not an "effective impervious area" (per the definition of "Effective Impervious Surface" (DOE Manual Volume I- Appendix G). Therefore this results in the project only having 470 sf of "effective impervious surface" which is less than a total of 10,000 square foot threshold of the "effective impervious surfaces". In addition the runoff increases less than 0.10 cfs during the 100-year flow frequency based on the WWHM model, therefore this project is exempt from providing Runoff Control as noted. Furthermore, since this is determined to P:FProjects1170201DOCSWDrarnage Memo 10.25.17.doc 4 be Flow Control exempt in accordance with DOE Manual section 2.5.7 as noted above, this project is not required to meet LID performance or standards as noted in section 2.5.5-Minimum Requirement #5-On-site Stormwater Management other than what is noted below. DOE MINIMUM REQUIREMENTS Based on the thresholds noted within the 2014 Department of Ecology Manual's Flow Chart for Determining Requirements (Figure 2.2) attached, the proposed single-family residential development requires the project to meet Minimum Requirements #1-9, however since the engineering analysis using an approved continuous model software shows that use of the infiltration trench will infiltrate the roof runoff, and it has calculated that there is sufficient area to the west of the new driveway to disperse and infiltrate runoff onto adjoining vegetated areas to remain, this project is not required to provide runoff controls, and subsequently only minimal Onsite Stormwater Management requirements as noted below. The following are the DOE Minimum Requirements #1-9 and how they are addressed: Minimum Requirement#1-Preparation of a Stormwater Site Plan The owner will provide a stormwater site plan which addresses development principles noted within this report. Minimum Requirement#2-Construction Stormwater Pollution Prevention (SWPP) Prior to commencing any construction the project's contractor must prepare a Construction Stormwater Pollution Prevention Control Plan that identifies the measures they will address each of the 13 Construction SWPPP Elements as necessary to prevent the erosion and discharge of sediment and other pollutants from the site. Minimum Requirement#3-Source Control of Pollution No source control BMP's are anticipated with this residential project. Minimum Requirement#4-Preservation of Natural Drainage Systems and Outfalls This project proposes to infiltrate runoff waters other than the small amount of runoff from the new sidewalk which will be conveyed to the existing drainage systems that currently receive runoff from the area. Minimum Requirement#5-On-Site Stormwater Management This item requires the employment of On-site stormwater management BMP's to encourage infiltration and dispersion of developed stormwater runoff. This project is not required to provide Runoff Control as denoted within this report,therefore it is also not required to provide LID Performance requirements, or follow List#1 or#2, however the project is required to implement BMP T5.13; BMP's T5.10 A, B, or C; and BMP's T5.11 and T5.12 as feasible. Infiltration has also been incorporated into the design for the both the roof and driveway runoff. P:lProjects1170201DOCS1DrainageMemo 10.26.17.doc 5 Minimum Requirement#6-Runoff Treatment Runoff treatment is required for all Pollution Generating Pervious and Impervious surfaces (PGPS and PGIS). The only pollution generating surface proposed it the driveway areas for this project,as roof runoff is considered non-pollution generating. The proposed driveway surface is to be constructed with a cross slope to direct runoff waters to disperse onto adjoining vegetated areas where there is sufficient width of vegetation to provide the 91'percentile storm runoff sufficient contact time to provide water quality before being discharged from the site. #7—Flow Control As previously noted per DOE section 2.5.7-Minimum requirement #7-Flow Control, a project is exempt from providing flow control if the project is: 1) The project has less than 10,000 square feet of effective impervious surfaces, 2) The project converts less than 3/4 acre of vegetation to lawn for landscape (or converts less than 2.5 acres of native vegetation to pasture), and 3) Through a combination of effective hard surface and converted vegetation areas cause less than a 0.10 cubic feet per second increase in the 100-year flow frequency as estimated using the WWHM model. Since this project has shown that both the roof and driveway have sufficient area infiltrate, based on the WWHM software analysis which makes these areas classified as "ineffective impervious area" (per the definition of"Effective Impervious Surface" (DOE Manual Volume I-Appendix G). Therefore this results in the project having less than a total of 10,000 square feet of "effective impervious surfaces". In addition the runoff increases less than 0.10 cfs during the 100-year flow frequency based on the WWHM model therefore this project is exempt from providing runoff control as noted. #8 -Wetlands Protection There is no discharge proposed from this site to any wetland. #9—Operations and Maintenance Not applicable to this project. P:1Projects1170201DOCStDrainage Memo 10.26.17.doc 6 STORMWATER EXHIBIT FIGURE I-2.4.1-FLOW CHART FOR DETEMINING RQMNTS FOR NEW DEVELOPMENT DOE DEFINITION OF EFFECTIVE IMPERVIOUS SURFACE INFILTRATION TRENCH DETAIL P:IProjectsl170201DOCSIDrainage Memo 10.26.17.doc 8 AP OXIMATE LOCA770IN OF I — — r 46° LONG x 2' WWDP X 2' DEEP DRIANROCK T LLW (KLN(;H fit' NUM I-UK KUUI UKA1115; - N PER INFILTRATION TRENCH DETAIL -- SS —SS 55 • SS SS ifSO C.S$ SS F—1. 5S S S— SS :AY o1 4 � I I " 46.00' Li 10.00' I-- U ►n { 70.00 1,-, 1 I 1 el CPA t I 111 I. I I I I ROOF LINE 1 1 4 b Da F' I PROPOSED in a`�'i WI HOUSE I t " ROOF AREA m 3,376 SF) I LU or I 1(�.67° 16.00' a SLOPE 1 MIN a, 20.00'• I da'Q P0 1 e d Li13 e 1 (� f a n _ _, J I-.. °$LOPF:ix Apt! _ IO4.92' - .� ` e lg o e d e a 6 Fl \ PROPOSED NEW SIDEWALK (47 SF) -- --�� _f/ s M M M 11 A M 15TH STREET vt - rt< ;pr-v [,• - ry IA- M M M M I IA M M 1 i Ravnik & Associates, Inc, ' »°: KT.& CIVIL ENGINEERING dt LAND-USE PLANNING STORM WATE R DRAWN BY: I*N 1633 LINDAMOOD LANER.O.BOX 361 BURLINOTON,WA 92233EXHIBIT PH:(360)mlzwa FAX:p m6o)� axw JOB NO, 17020 DAYS: 09.28.97 Figure 1-2.4.1 Flow Chart for Determining Requirements for New Development Start Here Does the site have 35% Yes See Redevelopment Minimum or more of existing Requirements and 'Flow Chart impervious coverage? (Figure 1-2.4.2). o Does the project convert 3/n ' acres or more of vegetation to Does the project result in lawn or landscaped areas, or 5,000 square feet, or KO) convert 2.5 acres or more of greater, of new plus native vegetation to pasture? replaced hard surface area? \NO Vag Does the project result in 2,000 square feet, or greater, of new plus • All Minimum Requirements replaced hard surface area? apply to the new and 'replaced halal surfaces and convened vegetation areas. " o Does the project have land 3ti>nirriom Requirements#1 h" disturbing activities of 7,000 through #5 apply to the new tua square feet or greater? Ties and replaced hard surfaces and the lend disturbed. N Minimum Requirement# applies. Hi ure Flow Chart for Determining Requirements for 'l'1!! 1 New Development DEPARTMENT OF Revised June 2015 ECOLOGY - Please see http:lhvww.ecy.wa.gov/copyrfght.htmi for copyright notice including permissions, State of Washington limitation of liability,and disclaimer. 2014 Starmwater Management Manual for Western Washington Volume 1 - Chapter 2 - Page 37 Drop structure A structure for dropping water to a lower level and dissipating its surplus energy; a fall. A drop may be vertical or inclined. Dry weather flow The combination of ground water seepage and allowed non-stormwater flows found in storm sewers during dry weather. Also that flow in streams during the dry season. - E - EIS See Environmental Impact Statement. ESC Erosion and Sediment Control (Plan). Earth material Any rock, natural soil or fill and/or any combination thereof. Earth material shall not be considered topsoil used for landscape purposes.Topsoil used for landscaped purposes shall comply with ASTM D5268 specifications. Engineered soil/landscape systems are also defined independently. Easement The legal right to use a parcel of land for a particular purpose. It does not include fee ownership, but may restrict the owners use of the land. Effective Impervious Surface Those impervious surfaces that are connected via sheet flow or discrete con- veyance to a drainage system. Impervious surfaces are considered ineffective it 1) the runoff is dispersed through at least one hundred feet of native vegetation in accordance with BMP T5.30: Full Dispersion (p.939); 2) residential roof runoff is infilt- rated in accordance with BMP T5.10A: Downspout Full Infiltration (p.905); or 3) approved continuous runoff modeling methods indicate that the entire runoff file is infiltrated. Embankment A structure of earth, gravel, or similar material raised to form a pond bank or found- ation for a road. Emergent plants Aquatic plants that are rooted in the sediment but whose leaves are at or above the water surface. These wetland plants often have high habitat value for wildlife and waterfowl, and can aid in pollutant uptake. 2014 Stormwater Management Manual for Western Washington Volume I-Appendix G- Page 157 4"DIA.RIGID PERFORATED PIPE FILTER FABRIC 2' 1' / FINISHED GRADE =l1� F—`-.a , ::.: a TOP 111� _I— SOIL I 1 Pi if iI 11 I=11 N WASHED ROCK "I "'l TRENCH DEPTH - II ; if lil-I BOTTOM �II�IISLT-IIIL_LLT- 11 1/2"TO 3/4" INFILTRATION TRENCH SECTION A—A WASHED DRAINROCK Ravnik & Associates, Inc. "E`D SCAM Kt/ CIVIL ENGINEERING 1 LAND•1JSE PLANNING INFILTRATION — 1.010411E0D enema BOX MI �D TRENCH EXHIBIT "BN°. "°'° DATE 110.7117 SOILS INFORMATION STORMWATER INFILTRATION EVALUATION MEMO P:IProjects1170201DOCSDDrainage Memo 10.26.17.doe 7 741 Mee Odve 'm BeWnphem.WA 98225 380 733_7318 �I oeccresT Ar ln9Mn.WA 982 3Avenue E 888 251 5270 360 733 7418 August 30,2017 Job No. 17-0425 Landed Gentry Homes and Communities 504 East Fairhaven Avenue Burlington,WA 98233 Attn.: Steven Baughn Re: Stormwater Infiltration Evaluation Padilla Adu Development 2202 15th Street Anacortes,Washington Dear Mr. Baugn, As requested, GeoTest Services, Inc. (GTS) is pleased to submit this report summarizing the results of our stormwater infiltration evaluation associated with the proposed single family residence at the subject property in Anacortes, Washington, as shown on the Vicinity Map(Figure 1). The purpose of this evaluation was to assess the existing subsurface conditions for use in designing stormwater infiltration system(s) associated with proposed development. This report summarizes our conclusions and recommendations regarding the potential for onsite stormwater infiltration. Specifically, our services included the following: 1, Evaluation of 3 test pits equally distributed across the subject property. Test pits explorations were advanced to7.5 feet below the ground surface(BGS). 2. Geological review of the information collected during this phase of the investigation in order to provide recommendations for the project. Our findings and recommendations are summarized in this site-specific report and contain the following information: • A site plan showing pertinent existing site features and the approximate location of the explorations accomplished for this project. • Logs of our explorations and results of our laboratory testing including a chart illustrating the soil classification criteria and the terminology and symbols used on the exploration logs. • Laboratory determinations of soil classification, including the long- term infiltration rates of soil encountered. Infiltration rates are based on USDA soil gradation analysis, in general accordance with the 2012 Stormwater Management Manual for Western Washington (SMMWW) amended December 2014. Laboratory evaluation on collected soils included USDA sieve analyses and moisture contents. Page 1 of 7 GeoTest Services, Inc. August 30,2017 2202 1e Street,Anacortes,WA Job No. 17-0425 A summary of surface and subsurface soil and groundwater conditions observed at the site during our field exploration. The summary includes descriptions of subsurface profiles and the potential seasonal effects of groundwater. The scope of services for this report included stormwater infiltration only, it does not include geotechnical recommendations with regards to the planned building foundation support, settlement, potential seismic considerations such as liquefaction and/or other geologic hazards that may exist within this property. PROJECT DESCRIPTION We understand that there are plans to develop the subject property with a single-family residence with associated stormwater facilities and utilities. As part of the development, the stormwater facilities will be constructed to accommodate onsite stormwater runoff from proposed impervious surfaces. The attached site and exploration map should be considered preliminary. SITE CONDITIONS This section discusses the general surface and subsurface conditions observed at the project site at the time of our field investigation. Interpretations of the site conditions are based on the results of our review of available information, site reconnaissance, subsurface explorations, laboratory testing, and our experience in the project vicinity. Surface Conditions At the time of our visit, the subject property was bordered by single family residences along its western and northern extent and D Avenue and 15th Street to its east and south, respectively. The property contained a 2 bay out building near its southwest corner and was covered in a grass lawn. In general, the property sloped slightly downwards towards the north, with elevation changes being less than about 5 vertical feet. Site Geology Geologic information for the project site was obtained from the 'Washington Interactive Geologic Map," published by the Washington State Department of Natural Resouces (DNR). According to this map, deposits at the project consist of Fraser-Age continental glacial till (Qgt). The till is a non-sorted and unstratified mixture of clay, sand pebbles, cobbles, and boulders (diamicton), deposited by glacial ice. The soils encountered in our subsurface explorations are generally consistent with the published geological information and our experience with projects in the nearby vicinity. Page 2 of 7 GeoTest Services,Inc. August 30,2017 2202 15Th Street,Anacortes,WA Job No. 17-0425 Subsurface Soil Conditions Subsurface conditions were explored by excavating 3 test pits (TP-1 through TP-3) on June 27, 2017. Approximate locations of these explorations have been plotted on the Site and Exploration Plan, Figure 2. The test pits were advanced with a tracked excavator to depths of 7.5 feet BGS. After test pit explorations were completed, the pits were backfilled with the excavated soils and compacted with the bucket of the excavator. In general, subsurface soils encountered within the area of proposed development consisted of approximately 0.5 to 1 foot of topsoil (soft, brown, moist, organic silt) that overlays 2 to 4 feet of weathered glacial till loose to medium dense, brown, moist, silty sand to slightly silty sand) with very stiff to hard, sandy silt with pebbles and cobbles (glacial till)extending to full depth within all 3 test pit locations. some minor fill soils were located above the weathered till in TP-2 and TP-3. Please refer to the attached exploration logs for more detail (Figures 4 through 5). Groundwater Seepage and Seasonal Groundwater For the purposes of this report, observed groundwater seepage represents either the existing surface of a groundwater table or the surface of perched seepage. The groundwater table is referred to as the atmospheric pressure surface that coincides with the top of the zone of saturation and is the surface that dictates the development design recommendations in this report. Perched scopage is referred to as a saturated zone that develops where a restrictive surface (i,e. dense, fine grained soils or bedrock) limits the vertical, downward migration of near-surface water. The groundwater table or perched seepage surface should be considered when determining methods of earthwork construction but is not used to dictate development design. Groundwater Observations At the time of our visit on June 27, 2017, minor, perched groundwater seepage was observed within the test pits between 4.5 and 6.0 feet BGS. As the region has not, at the time of our site visit, recently experienced precipitation, we interpret the groundwater to be interflow running along the very dense till soils with elevated fines content, generally encountered onsite at approximately 4.5 to 6.0 feet BGS_ During periods of extended and/or heavy rainfall we would anticipate that groundwater would be found perched on the very dense till soils with elevated fines content. Seasonal Groundwater Fluctuation Observations A distinct mottled horizon or "rust line," was not encountered within the test pit explorations. Mottling (reddish-brown, orange, or yellow splotches or mottles) is typically indicative of soils that experience fluctuating moisture conditions, generally due to seasonal wetting and drying. Gleyed soils, indicative of poorly drained and potentially restrictive soils, were encountered within the unweathered, very stiff to hard till. Gleyed soils are typically gray or bluish-gray in color and the result of a reduced (non-oxidative) soil state caused by Page 3 of 7 GeoTest Services,Inc. August 30,2017 2202 15th Street,Anacortes,WA Job No. 17-0425 significant periods of saturation. Gleyed soils are often associated with soils that are restrictive of groundwater flow. Please note that changes to soil color and morphology may take significant periods of time to develop and may not be reliable indicators of groundwater conditions in areas that have experienced significant recent changes in hydrology. Additionally, in areas of fill, sufficient time may not have passed since fill placement for these indicators to develop. Not all hydric soils exhibit mottled and/or gleyed horizons. Their presence or absence alone should not dictate the interpretation of site groundwater conditions. Sources of groundwater table fluctuations As groundwater table levels and/or seepage rates are typically not static, it is anticipated that groundwater conditions will vary depending on local subsurface conditions, season, precipitation, changes in land use both on and off site and other factors. Markedly, we anticipate that groundwater conditions on site are largely influenced by seasonal variations of precipitation. Considerations GTS considers the depth at which groundwater seepage stabilizes and ponds to be the groundwater table. Groundwater seepage will influence stormwater management facilities and should be considered when designing those facilities. The groundwater conditions reported on the test pit logs are for the specific locations and dates indicated, and therefore may not necessarily be indicative of other locations and/or times. Please consider that groundwater table levels are generally higher (at shallower depths)during the wetter months(October through May). Our construction recommendations consider the groundwater conditions encountered at the time of our field investigation, in association with the project design provided at the time of this report. It is the clients and their (his/her) representative's responsibility to inform GTS of variations in groundwater conditions and/or any modifications to project designs so that a review of and revision to report recommendations can be made, if necessary. Unless specifically requested, GTS is not responsible to provide monitoring of groundwater conditions beyond the time of our site investigations. Please keep in mind that groundwater conditions may be different if there is a substantial lapse of time between submission of this report and the start of construction. If this is the situation, GTS recommends we be contacted to evaluate groundwater conditions in order to determine whether our report conclusions and recommendations remain applicable. RESULTS Stormwater Infiltration Potential Test Pit Gradation Results From the explorations excavated in the areas of interest, 13 representative soil samples were selected and mechanically tested for grain size distribution and calculation according to the 2012 Stormwater Management Manual for Western Washington Page 4 of 7 GeoTest Services,Inc, August 30,2017 2202 1511'Street,Anacortes,WA Job No.17-0425 (SMMVVVV) amended December 2014, soil grain size analysis method, Section 3.3.6. A summary of these results are reproduced in Table 1 below. TABLE 1 Test Pit Sod Sample Infiltration Rate 012 SMMWW amended Decemb r Test Pit Sample DesignGeologic K.i Uncorrected Rate Dealgn Infiltration fiats ID Depth USGS Unit Per AVM D422 Simplified Approach(inches/Hour) TP-1 1.0 SM Weathered Till 9.30 1.51 TP-1 2,0 SP-SM Weathered Till 38.09 6.17 TP-1 4.5 SP-SM Weathered Till 48.08 7.79 TP-2 2.5 SM Weathered Till 9.26 1.50 TP-2 5.0 ML Glacial Till 2.24 0.38 TP-3 2.0 SM Weathered Till 11.71 1.90 TP-3 3.5 SP-SM Weathered Till 39.08 6.33 Notes; -Ksat=Initial Saturated Hydraulic Conductivity -Listed Infiltration rates are estimated long-term(design)rates based on the soil grain size analysis method. -Correction Factors Used:CFI=0.70 In the simplified approach (Section 3.3.4) the infiltration rate is derived by applying appropriate correction factors to the measured saturated hydraulic conductivity (K,at) from the ASTM 422 grain size analysis. Saturated hydraulic conductivity is a quantitative measure of a saturated soil's ability to transmit water when subjected to a hydraulic gradient. It can be thought of as the ease with which pores of a saturated soil permit water movement. Saturated Hydraulic Conductivity is expressed as follows: Lo910(Ksat)=-1.57+ 1.90Di0+0.015D6o--0.013D90-2.08fnnos Where D10, Dot, and D90 are the grain sizes in mm for which 10 percent, 60 percent, and 90 percent is more fine and ffin„is the fraction of the soil(by weight)that passes the U.S. No. 200 sieve. Ksat is measured in cm/sec. With this equation, we can determine the saturated hydraulic conductivity for our representative samples. See example below: Test Pit TP-1 at 1.0 foot BGS: K = 0.006562964 cm/sec or approximately 9.30 inches/hour. Applying correction factors for site variability (0.45), test method (0.4) and degree of influent control to prevent siltation and bio-buildup (0.9) gives a corrected long term design rate of 1.51 inches/hour for the example above. Based on the 2012 SMMWW(amended December 2014)soil grain size analysis method and our applied correction factors, the weathered glacial till soils located below the topsoil contains estimated long term design infiltration rates ranging between 7.79 and 1.50 in/hr Accordingly, we recommend using the lowest result value of 1.50 in/hr for use in design for the weathered glacial till. Page 5 of 7 GeoTest Services,Inc. August 30,2017 2202 15th Street,Anacortes,WA Job No. 17-0425 Stormwater Pollutant Treatment The stormwater facilities on-site may require some form of pollutant pre-treatment or treatment with an amended soil prior to onsite infiltration or offsite discharge. It is our opinion, based on past experience, that the re-use of onsite topsoil and weathered Outwash Soils is often the most sustainable and cost effective method for pollutant treatment purposes. Cation exchange capacities, organic contents, and pH of site subsurface soils were determined to establish their pollutant treatment suitability. Cation Exchange Capacity, Organic Content and pH Testing Three composite samples were collected during our subsurface explorations for pollutant treatment purposes. Cation exchange capacity (CEC), organic content (LOI), and pH tests were performed by Northwest Agricultural Consultants. Laboratory test results are presented in Table 2. r--- Test Pit Sample Cation Exchange Capacity Organic Content pH ID Depth(1t) (megll0a grams) (%) TP-1 1.5 11.8 6.34 5.6 TP-2 8.0 21.5 7.78 5.5 TP-3 3.5 6.1 3.65 6.6 Criteria SSC-6 states that cation exchange capacity must be greater than or equal to 5.0 meg1100 grams and organic content must be a minimum of 1.0 percent for treatment purposes. Based on the results listed in Table 2, the Topsoil and weathered glacial till appear to be suitable for onsite pollutant treatment purposes based on the SSC-6 of the 2012 Washington State Department of Ecology Stormwater Management Manual for Western Washington. Additional considerations to using infiltration as a treatment option include the soil infiltration rate! drawdown time as described in SSC-4 of the 2012 Washington State Department of Ecology Stormwater Management Manual for Western Washington. A maximum drawdown time is applied to some types of infiltration based water quality design facilities. LIMITATIONS The scope of services for this report included stormwater infiltration only, this report is not intended to address other geotechnical concerns with regards to the planned building foundation support, settlement, potential seismic considerations such as liquefaction and/or other geologic hazards that may exist within this property. GeoTest can perform additional geotechnical evaluation and/or analysis, with regards to the above mentioned geotechnical items, upon request. The analyses, conclusions, and recommendations provided in this report are based on conditions encountered at the time of the subsurface exploration performed by GeoTest Services, Inc., information from previous studies and our experience and judgment. Our work has been performed in a manner consistent with that level of care and skill ordinarily exercised by members of the profession currently practicing under similar Page 6 of 7 Georest Services,Inc. August 30,2017 2202151n Street,Anacortes,WA Job No, 17-0425 conditions in this area. GeoTest Services has prepared this report for the exclusive use of Landed Gentry Homes and Communities and their design representatives for specific application to the proposed new development located 2202 15th Street in Anacortes, Washington. No warranty, expressed or implied, is made. We must presume the subsurface conditions encountered are representative for the proposed site for the purposes of formulating our recommendations. However, you should be aware that subsurface conditions may vary with time and between exploratory locations, and unanticipated conditions may be encountered. If construction reveals differing conditions or the design is modified, we should be retained to reevaluate our recommendations and provide written confirmation or modification, as needed. We appreciate the opportunity to be of service to you on this project. If any questions should arise regarding this report, please contact the undersigned. Respectfully Submitted, GeoTest Services, Inc. V7r Ars- '\c-p',\ ed Tim Chylla] Tim Chylla, L.E.G. Engineering Geologist Attachments Figure 1 Vicinity Map Figure 2 Site and Exploration Plan Figure 3 Soil Classification System and Key Figures 4-5 Logs of Test Pits Figures 6-7 Grain Size Distribution Northwest Agricultural Results(1 page) ASFE-Report Limitations and Guidelines For Its Use(3 pages) References Interactive Geologic Map of Washington State. Online interactive services provided by the Washington State Department of Natural Resources. Washington State Department of Ecology, 2012 (amended December 2014). Stormwater Management Manual for Western Washington. Page 7 of 7 PROJECT LOCATION IJ )t ^S' \\\ . . Ilya ' y 6ih St > 1.. ,1 R 1 t, 1.' .1 +' Ciip S IIJt(?i,,. nk. •11.I%I P. , ..- I7.C'1 ?HIS ,f1 1 rc1 31h:t ' t 1- 1 V. 1 •1 rm Volunteer Park r • .1i4.0's v. •V 01 s y'n'X n' ` Anacortes'Martna • 4 v1. K D ;..e a I. 1Cranberry In A,n.lc.cxle!..: Lake Park w tamer• e• r.` " Atrpor1 01•$. _ - ' 'lorh 1 A. \ ' t4' it a151 1 ' ti A let 11 l 'rttl`.• yI1! 1 Isl.s ,.al g _ r r! ,`k, ..-. r 5�1 �h t,v N. X ` 1. �' . I K n L. [n, I tii1:t i �y,,,•k Y. MAP REFERENCED FROM GOOGLE MAPS I tr'''''N,,,, ^-- — Date: 8-30-17 By: JS Scale: As Shown Project GEOTEST SERVICES INC. VICINITY' MAR � �25 741 Marine Drive Bellingham, WA 98225 PADILLA ADU Figure Phone: (360) 733-7318 2202 15TH STREE"f fax (369) 733-7418 ANACORTES, WASHING TON 11 PROJECT LOCATION �� I rl • Mt l r ■ . 0 M .. C c • CD i , - T' .rriii 1 4 lir 1 Y ill 15th Street F ,C(th MAP REFERENCED FROM GOOGLE MAPS Si TP4=Approximate Test Pit Location A 1 N Date: 8-30-17 By: JS Scale: As Shown Project CIFOTEST SERVICES, INC. SITE AND EXPLORATION PLAN '17-0425 741 Marine Drive Bellingham, WA 98225 PADILLA ADU Figure phone: (360)733-7318 2202 15TH STREET fax: (300)733-7418 ANACORTES,WASHINGTON i Soil Classification System usCs MAJOR GRAPHIC LETTER TYPICAL DIVISIONS SYMBOL SYMBOL DESCRIPTIONSt11(2) - 0 ....0. Er GRAVEL AND CLEAN GRAVEL D •a. o ° GW Well-graded gravel;gravel/sand trrxture(s);little or no fines GRAVELLY SOIL (Little or no fines) o a a.0- 0 :idc o 1D . o o Gp Poorly graded gravel;gravel/sand mixture(s);1it91e or no fines 0 •m g+ More than 50%of " * '• " ui ( GRAVEL WITH FINES " ' GM Sly gravel;gravel/sand/silt mixture(s) m � coarse fradion retairtect � " ' " E Si on No,4 sieve) (Appreciable amount of a ' a c� fines) Clayey gravel;gravel/sand/day mixture(s) NI wo e W Well-graded sand;gravely sand;little or no fines s SAND AND CLEAN SAND • SANDY SOIL (Little or no fines) • do® SP Poorly graded send;gravelly sand;finis or no fines 0 -m 2 (More than 60%of u SM Silty sand;sandlsitt mixture(s) coarse fraction passed SAND WITH FINES through No.4 sieve) (Appreciable amount of ) • : fines) • SC Clayey sand; sand/day mixture(s) Inorganic silt and very fine sand; rock flour;silty or dayey fine g SILT AND CLAY ML sand or clayey sift with slight plasticity (Jm Inorganic day of low to medium plasticity; gravelly day;sandy © E N (Liquid limit less than 50) day;silty day;lean clay W Qci e -CD- ()L Organic silt;organic,silty day of low plasticity O C N - 2, w MH Inorganic silt; micaceous or diatomaceous fine sand 921 6, SILT AND CLAY Z O (Liquid limit greater than 50) Inorganic day of high plasticity;fat clay Li . , OH Organic clay of mcriurn to high plasticity; organic sift HIGHLY ORGANIC SOIL PT Peat; humus;swamp soil with high organic content GRAPHIC LETTER OTHER MATERIALS SYMBOL SYMBOL TYPICAL DESCRIPTIONS PAVEMENT AC or pc Asphalt concrete pavement or Portland cement pavement ROCK ���'` RK Rock(See Rock Classification) WOOD y✓ ; WDWood,lumber,wood chips A AA A. DEBRIS 0 0 l D Construction debris,garbage n n n/ Notes: 1. Soil descriptions are based on the general approach presented in the Standard Practice for Description and Identification of Soils(Visual-Manuel Procedure), as outlined in ASTM D 2488.Where laboratory index testing has been conducted, soil classifications are based on the Standard Test Method for Classification of Soils for Engineering Purposes, es outlined in ASTM D 2487. 2. Soil description terminology is based on visual estimates(in the absence of laboratory test data)of the percentages of each soil type and is defined as follows: Primary Constituent: >50%-"GRAVEL,'"SAND,""SILT,""CLAY,"etc. Secondary Constituents: >30%and<50%-"very gravely,""very sandy,""very silty,"etc. > 12%acid<30%-"gravely,""sandy,'"silty,"etc. Additional Constituents: > 6%and t 12%-"slightly gravely,""slightly sandy,""slightly silty,"etc, < 5%-"trace gravel,""trace sand,""trace silt,"etc., or not noted. Drilling and Sampling Key Field and Lab Test Data SAMPLE NUMBER&INTERVAL SAMPLER TYPE Code Description Code Description Sample Identification Number a 3.2a ink O.D.,242-inch I.D.Split Spoon PP=1.t) Packet Penetrometer,tsf b 2.00-inch O.D., 1.50-Inch I.D.Split Spoon TV=0,5 Torvane,tsf s- Recovery Depth Interval c Shelby Tube P1D= 100 Photoionization Detector VOC screening, ppm 1 114— Sample Depth Interval Recovery Grab Sample W-10 Moisture Content, % a Other-See text if applicable 0= 120 Dry Density,pcf Portion of Sample Retained 1 30G-tb Hammer,30-inch Drop -200=60 Material smaller the No, 200 sieve,% for Archive or Analysis 2 140-tb Hammer,30-inch Drop GS Grain Size-See separate figure for data 3 Pushed AL Atterberg Limits-See separate figure for data 4 Other-See text if applicable GT Other Geolechniml Testing Groundwater CA Chemical Analysis Q Approximate water elevation at time of dril¢ing(ATD)or oh date noted. Groundwater ATD levels can fluctuate due to precipitation,seasonal conditions, and other factors. --"- '1 Padilla Mu Figure Geare5 :_ 2202 15th Street Soil Classification System and Key 3 Anacortes, Washington . _ . _..._.a—.._.. - TP-1 1 SAMPLE DATA SOIL H`'ii 4, t1LE GROUNCDIN fi -i; -6 — 0, Tracked Excavator a E �_a`�' Excavation Method: ham- ro E., cra Ground Elevation (ft): Unknown co m c fa ) l U n CO 0 u7 a- CD D __ � s OL T Son,brown, moist,organic SILT(Topsoil) i-1� d SM Loose to medium dense,brown,moist, very silty _� 1-2111: d GS to silty,fine SAND(Weathered Till) -2 --` 1-3 AL d GS , slit content decreases,becomes coarse to fine 1, SAND -i O .. o I-- —.tl 11 ILI( 1�lIE d GS 1i_ _ A% Slight1-5 d [�4L stiff tohard,moist,bluish gray, sandy SILT i 2. 6 I pebblesand cobbles( adal Till) lI o f ¢ 1.6 1 - - ' �fl� d � I--��--- • f3 Test Pit Completed 0e/27117 - Total Depth of Test Pit=7.5 ft. j o. a .- 0 a a. SAMPLE DATA SOIL PROFILE GROlJ[liMA 'Eti cu , 1 r, aE c ,°o Excavation Method: Tracked Excavator i.1 (a u' �' Unknown rJ 't m m m 0 co Ground Elevation (ft): if>, To.' N Q. d ro 'n. E c E 08 r (03 i ' u) OD - U D i— p li ,' t]LLoose,brown,dry,sli ( fine sand withT I- slightly silty, z 2.-1 - ci Organics(Topsoil) 1. �" SM Loose to rneclum dense,brown,moist,very silty .�j i —2 to silty,fine SAND with organics(Fin) ' d C;:3 $M Loose to medium dense,brown,moist,very silty J to silty,fine SAND(Weathered TM) ,- 1 o _ w ,-4 NIL Verystiff to hard,moist,bluish spght N. . gray,sandy SILT with pebbles and cobblers(r Gadail Tiff) N I- 2-3_I d ( a - U i--- h - a' - a._ 24 I; d k 0 8 —aIL Test Pit Completed 06127117 Taal Depth of Test Pit=7,5 ft. N. w —10 at a.1 k i Notes: 1. Stratigraphic contacts are based on field interpretations and ere approximate. 1 rr 2. Reference to the text of this report is necessary for a proper understanding of subsurface conditions. a) 3. Refer to"Soil Classification System and Key'figure for explanation of graphics and symbols. m, Padilla Adu -- - --�- -- .�-�Ic tt,itE, ceoTe5r 2202 15th Street Log of Test Pits l Anacortes, Washington - -- - - _ =f_1 of 2) i . , . TP-3 SAMPt.E. DATA 8(41, PROFILE GROUNIDINATER _ io- Excavation Tracked Excavator a ci icc'J Method'_ = ,>-• --_," , E Ground Elevation (ft): Unknown 0 a) 83 .._. rn 05 CO— CO 0 -- </3 C.) U)04 rio I- (9 1 : SM stilt brown,moist,silty,medium to fine SAND 3-1 irc d Os 1 WM gravel and cobbles(All) 1 • , OL Scfl,black to brown,moist,organic SILT(Relic 9 ' SM Topsoil) ,/-- l, ''- , Loose to medium dense,brown,moist,very silty o i , i / to silty,fine SAND(Weathered Till) 9 I 3-31E- ti sill content decreased — IL- - sill 119 1- sill content increased I- -- 3--4 E d .2 Sti ht ML Very stiff to hard,moist,bluish gray,sandy SILT - 9 < i with pebbles and cobbles(Glad Till) - 5 13 Test Pit Completed 06/27117 0_ Total Depth of Test Pit=7.5 ft. n o < ' ri LO " ! I,- >--1 IX I- Z W 1 0 10, 0 Z , 5 ...., iS I F:r i m i ID Z I 71 0 P. < I:1 LI) L? I-- g 01 U3 I- 0 1. It"1 8 1 c. 1 q i -21 (1) i CO I--- tti °I• 9 No : 1. Stratigraphic contacts are based on field interpretations and we appro)dmate. t-- 2. Reference to the text of this report is necessary for a proper understanding of subsurface conditions. :-.. "("1 3. Refer to"Solt Classification System and Key"figure for explanation of graphics and symbols. . . 1 Padilla Adu Figure IoeoTe5T 2202 15th Street Log of Test Pits Anacortes, Washington ___ ,) (2 of 2) U.S.SIEVE OPENING IN INCHES I U.S.SIEVE NUMBERS I HYDROMETER 6 4 3 2 16 3f 1 1I2.s. 3 6 10 16 30 50 100 200 �4 � a 14 20 40 60 140 , 90 - 'N. Ihtsi lki . bk Mil ---.-L---_....__ II,: . .. - iillti k 0 T Q. ;= cg •�60 N g50 , • • Q 0_40 . a 5' 30 --, -- . •-_- -_., ' a - , `- -3 I I a I 20 - 1- _ .. - -------- N - _ . 10 _ . .. . 1-- II • . C'1 • 0 0 `v 100 10 1 0.1 0.01 0.001 • Grain Size in Millimeters z F I Gravel Sand a 1 Cobbles - Silt or Clay r; coarse fine coarse medium fine v, .. - w g Point Depth Classification LL PL PI Ce Cu g t TP-1 1.0 Silty, tine SAND (SM) E ® TP-1 2.0 Slightly silty,fine SAND (SP-SM) 1.43 2.42 A TP-1 4,5 Slightly silty, coarse to fine SAND with trace gravel (SP-SM) _ 1.52 5.35 o * TP-2 2.0 Silty, medium to fine SAND with trace gravel (SM)Pi __I 2 O TP-2 5.0 1 Very sandy SILT (ML) -y iu °%Coarse °T ine %Coarse %Medium %F nT - %`ices Point Depth Dino Aso D50 d3a D�a Gravel Gravel Sand Sand _, Send o • TP-1 1.0 4.75 0.168 0.137 0.076 0.0 0.0 0.6 4.5 65.5 29.4 8 MI TP-1 2.0 9.5 0.197 0.181 0,152 0.081 0.0 0.1 0.2 0.7 91.6 7.4 ES 6. TP-1 4.5 19 0.776 0.632 0414 0,145 0.0 5.3 9.1 54.8 23.7 7.1 21�'° TP-2 2.0 37.5 0.258 0.191 0.054 5.8 2.9 A 3,8 16.1 43.5 27.8E U TP-2 6,0 9.5 0.079 0.0 0.7 1.4 8.1 30.8 59.0 6 k C�= D302I(D60* Dio) To be well graded: 1 < C, < 3 and Cu = DeroiDia Cu > 4 for GW or Cu > 6 for SW f Padilla Adu Fico ire ioec7eoTeT2202 15th Street Grain Size Test Data i Anacortes, Washington 6 f' U.S. SIEVE OPENING IN INCHES I U.S.SIEVE NUMBERS I HYDROMETER 4 2 1 - 1/2,16- 3 4 6 10 16 30 50 100 200 ii 6 3 1.6 8, 14 20 40 60 140 : 90 , ----.— , 1 80 - I .. ,. . F- -I-. F- to Q z 60 t cl .53 O ii- ..-- 0 ,0 113 6 E.) 40 - ' — , , --\vii. .5 1 -an , a \ill < 20 a. tr) 9 '• . . . . . • - w - , 1.- . . (.9 •. •. -• O 0 i • • .• , , - _ . . w, - a 1.00 10 1 0.1 0.01 0.001 Grain Size in Millimeters ilf) Gravel Sand 61 Cobbles Silt or Clay come line coarse medium fine 6 Point Depth Classification LL PL PI C, Cu P _ p. e 1 TP-3 2..0 Silty,the SAND (SM) 5- Ill TP-3 3.5 Slightly silty, coarse to fine SAND with trace gravel (SP-SM) 1,05 4.58 2 - 0 0 1-. ill %Coarse %Fine %Ccrarse %Medium %Fine e., Point Depth Dun Doo D50 D30 DiD Gravel Gravel Sand Sand Sand %Fine5 TP-3 2.0 9.5 0.182 0.158 0.089 0.0 0.0 02 2.6 72.6 24.6 8 kJ TP-3 3.5 19 0.499 0.367 0.239 0.109 0.0 9.5 9.4 _ 24.1 50.0 7.0 w I- (..> w _ . 3 a 5i. Cc = D302/(Doo* D10) To be well graded: -I < C,< 3 and S Cu = Duo/D i 0 Cu > 4 for GW or Cu > 6 for SW _. Padilla Adu Figure clleoTe5T 2202 15th Street Grain Size Test Data Anacortes, Washington - _ 1 ) 'I iJorthvi ct Aprickkuraf GeoTest Services Inc. ..: . , ._ n _n `` 741 Marine Drive Bellingham,WA 98225 2545 W Falls Avenue PAP-Accredited Kennewick,WA 99336 1 509.783.7450 i , Report:41439-1 www.nwag.com lab@nwag.com NAP-7 Date:June 30,2017 Project No:17-0425 Project Name: Padilla Adu Sample ID pH Organic Matter Cation Exchange Capacity TP-1 @ 1.5' 5.6 6.34% 11.8 meq/100g TP-2 @ 5.0' 5.5 7.78% 21.5 meq/10og TP-3 @ 3.5' 6.8 3.65% 6.1 meq/100g Method SM 4500-Hi B ASTM D2974 EPA 9081 1 REPORT LIMITATIONS AND GUIDELINES FOR ITS USE' Subsurface issues may cause construction delays, cost overruns, claims, and disputes. While you cannot eliminate all such risks, you can manage them. The following information is provided to help: Geotechnical Services are Performed for Specific Purposes, Persons, and Projects At GeoTest our geotechnical engineers and geologists structure their services to meet specific needs of our clients. A geotechnical engineering study conducted for a civil engineer may not fulfill the needs of an owner, a construction contractor or even another civil engineer. Because each geotechnical engineering study is unique, each geotechnical engineering report is unique, prepared solely for the client. No one except you should rely on your geotechnical engineer who prepared it. And no one—not even you—should apply the report for any purpose or project except the one originally contemplated. Read the Full Report Serious problems have occurred because those relying on a geotechnical engineering report did not read it all. Do not rely on an executive summary. Do not read selected elements only. A Geotechnical Engineering Report is Based on a Unique Set of Project-Specific Factors GeoTest's geotechnical engineers consider a number of unique, project-specific factors when establishing the scope of a study. Typical factors include: the clients goals, objectives, and risk management preferences; the general nature of the structure involved its size, and configuration; the location of the structure on the site; and other planned or existing site improvements, such as access roads, parking lots, and underground utilities. Unless GeoTest, who conducted the study specifically states otheiwise, do not rely on a geotechnical engineering report that was: • not prepared for you, • not prepared for your project, • not prepared for the specific site explored, or • completed before important project changes were made. Typical changes that can erode the reliability of an existing geotechnical engineering report include those that affect: • the function of the proposed structure, as when it's changed, for example, from a parking garage to an office building, or from a light industrial plant to a refrigerated warehouse, • elevation, configuration, location, orientation, or weight of the proposed construction, • alterations in drainage designs; or • composition of the design team; the passage of time; man-made alterations and construction whether on or adjacent to the site; or by natural alterations and events, such as floods, earthquakes or groundwater fluctuations; or project ownership. Always inform Geolest's geotechnical engineer of project changes — even minor ones — and request an assessment of their impact. Geotechnical engineers cannot accept responsibility or liability for problems that occur because their reports do not consider developments of which they were not informed. 'Information in this document is based upon material developed by ASFE,Professional Firms Practicing in the Geosciences(esfe.org) oeoTesT Subsurface Conditions Can Change This geotechnical or geologic report is based on conditions that existed at the time the study was performed. Do not rely on the findings and conclusions of this report, whose adequacy may have been affected by: the passage of time; by man-made events, such as construction on or adjacent to the site; or by natural events, such as floods, earthquakes, or groundwater fluctuations. Always contact GeoTest before applying the report to determine if it is still relevant. A minor amount of additional testing or analysis will help determine if the report remains applicable. Most Geotechnical and Geologic Findings are Professional Opinions Our site exploration identifies subsurface conditions only at those points where subsurface tests are conducted or samples are taken. GeoTest's engineers and geologists review field and laboratory data and then apply their professional judgment to render an opinion about subsurface conditions throughout the site_ Actual subsurface conditions may differ—sometimes significantly—from those indicated in your report. Retaining GeoTest who developed this report to provide construction observation is the most effective method of managing the risks associated with anticipated or unanticipated conditions. A Report's Recommendations are Not Final Do not over-rely on the construction recommendations included in this report. Those recommendations are not final, because geotechnical engineers or geologists develop them principally from judgment and opinion. GeoTest's geotechnical engineers or geologists can finalize their recommendations only by observing actual subsurface conditions revealed during construction. GeoTest cannot assume responsibility or liability for the report's recommendations if our firm does not perform the construction observation. A Geotechnical Engineering or Geologic Report may be Subject to Misinterpretation Misinterpretation of this report by other design team members can result in costly problems. Lower that risk by having GeoTest confer with appropriate members of the design team after submitting the report. Also, we suggest retaining GeoTest to review pertinent elements of the design teams plans and specifications. Contractors can also misinterpret a geotechnical engineering report. Reduce that risk by having GeoTest participate in pre-bid and preconstruction conferences, and by providing construction observation. Do not Redraw the Exploration Logs Our geotechnical engineers and geologists prepare final boring and testing logs based upon their interpretation of field logs and laboratory data. To prevent errors of omissions, the logs included in this report should never be redrawn for inclusion in architectural or other design drawings. Only photographic or electronic reproduction is acceptable; but recognizes that separating logs from the report can elevate risk. Give Contractors a Complete Report and Guidance Some owners and design professionals mistakenly believe they can make contractors liable for unanticipated subsurface conditions by limiting what they provide for bid preparation. To help prevent costly problems, give contractors the complete geotechnical engineering report, but preface it with a clearly written letter of transmittal. In that letter, consider advising the contractors that the report was not prepared for purposes of bid development and that the report's accuracy is limited; encourage them to confer with the GeoTest and/or to conduct 'Information in this document is based upon material developed by ASFE,Professional Firms Practicing in the Geosciences(aete.org) oeoiesT additional study to obtain the specific types of information they need or prefer. A pre-bid conference can also be valuable. Be sure contractors have sufficient time to perform additional study. Only then might you be in a position to give contractors the best information available, while requiring them to at least share some of the financial responsibilities stemming from unanticipated conditions. In addition, it is recommended that a contingency for unanticipated conditions be included in your project budget and schedule. Read Responsibility Provisions Closely Some clients, design professionals, and contractors do not recognize that geotechnical engineering or geology is far less exact than other engineering disciplines. This lack of understanding can create unrealistic expectations that can lead to disappointments, claims, and disputes. To help reduce risk, GeoTest includes an explanatory limitations section in our reports. Read these provisions closely. Ask questions and we encourage our clients or their representative to contact our office if you are unclear as to how these provisions apply to your project. Environmental Concerns Are Not Covered in this Geotechnical or Geologic Report The equipment, techniques, and personnel used to perform an environmental study differ significantly from those used to perform a geotechnical or geologic study. For that reason, a geotechnical engineering or geologic report does not usually relate any environmental findings, conclusions, or recommendations; e.g., about the likelihood of encountering underground storage tanks or regulated containments, etc. If you have not yet obtained your own environmental information, ask your geotechnical consultant for risk management guidance. Do not rely on environmental report prepared for some one else. Obtain Professional Assistance to Deal with Biological Pollutants Diverse strategies can be applied during building design, construction, operation, and maintenance to prevent significant amounts biological pollutants from growing on indoor surfaces. Biological pollutants includes but is not limited to molds, fungi, spores, bacteria and viruses. To be effective, all such strategies should be devised for the express purpose of prevention, integrated into a comprehensive plan, and executed with diligent oversight by a professional biological pollutant prevention consultant. Because just a small amount of water or moisture can lead to the development of severe biological infestations, a number of prevention strategies focus on keeping building surfaces dry. While groundwater, water infiltration, and similar issues may have been addressed as part of this study, the geotechnical engineer or geologist in charge of this project is not a biological pollutant prevention consultant; none of the services preformed in connection with this geotechnical engineering or geological study were designed or conducted for the purpose of preventing biological infestations. 'Information in this document is based upon material developed by ASFE,Professional Firms Practicing in the Geosciences(aste.org) ito are',i 741 Marine pave Bellingham,WA 98225 360 733_7318 2 .Avenue CMG TG'ST AM�ng10n7 WA 98223E 888 251_5276 360 733_7418 October 24, 2017 Job No. 17-0425 Landed Gentry Homes and Communities 504 East Fairhaven Avenue Burlington, WA 98233 Attn.: Steven Baughn Re: Stormwater Infiltration Evaluation Memo Padilla ADU Development 2202 15th Street Anacortes, Washington Dear Mr. Baughn, As requested, GeoTest Services, Inc. (GTS) is pleased to submit this memorandum disusing the effects of stormwater from the proposed infiltration trench on the adjacent residential foundations. It is our understanding that the City of Anacortes Planning Department has concerns that the foundation setback distances from the trench might not meet the suggested guidelines put forth in the 2014 DOE Stormwater Manual for Western Washington and may have 'a significant negative impact on the surrounding foundations'. The manual suggests that infiltration trenches be placed at least 20 feet from uphill foundations and 100 feet away from downhill foundations. The proposed infiltration trench is to be situated 20 feet north of the proposed residence on the subject property and runs east to west for 46 feet. The existing residence on the neighboring property to the north is 48 feet away from the proposed infiltration trench. Topography on the property slopes gently downward to the north, dropping approximately 1 foot in elevation from the trench to the neighboring residence, giving a gradient of 1 degree or 2 percent. Based upon the relatively flat topography and the fact that the upper 4 feet of the existing site soils contain weathered till that can be infiltrated into at a rate of 1.5 inches per hour, in our opinion, it is extremely unlikely that the location of the proposed trench would negatively impact the surrounding foundations. Page 1 of 2 GeoTest Services,Inc. October 24,2017 2202 15th Street,Anacortes,WA Job No. 17-0425 We appreciate the opportunity to be of service to you on this project. If any questions should arise regarding this report, please contact the undersigned. Respectfully Submitted, GeoTest Services, Inc. 9' 424 $ed Gs('‘ ? Tim Chylla Tim Chylla, L.E.G. Engineering Geologist Attachments Figure 1 Vicinity Map Figure 2 Site Plan References Washington State Department of Ecology, 2012 (amended December 2014). Stormwater Management Manual for Western Washington. Page 2 of 2 PROJECT LOCATION III 110111111-- t. + ilio , ,.1' , y C ai 1J1 1 0il Ail 140 L.,t. � 'hfi St `` a . 1 '1,4 J 1 ,1 1 e I h r + illt; . ' I \ li : 1 ;. Z. ' MAP REFERENCED FROM GOOGLE MAPS Date: 8-30-17 By: JS 1 Scale: As Shown Project GEOTEST SERVICES, INC. VICINITY MAP 17-0425 741 Marine Drive Bellingham, WA 98225 PADILLA ADU Figure phone: (360)733-7318 2202 15TH STREET fax: (360)733-7418 ANACORTES,WASHINGTON 1 — — - - - srr A RR:Rr_✓I 4T ED L ECM. DE SCRIP ION: - ?d' ',AS' PALP or Lo' 17. ALONG MATH ALL Cr LOTS 18. a :9, AND 20. 0= 8_CCP: 20S. AS PER SURVEY RECORDED ah E •v✓.7CR'5 Psi !'NUMBER 20030_7170-' b, RCCORDS ;:c:.: —. _ .. or i+AE!r COW.7r. STA : — 2:- WASTLINGTV.V . I . .a N D I . U „ . . . 'd' RV BM FENCE PERIMETER SAT NCR GENERAL NOTES PROTECT DOWNSTREAM PROPERTIES nw,,,ER. LAI:GEO GENTLY • SOL E. FAIANAY(J. BULINGTON. WA • v'Yes1 r43EOI-2S5-11021 ALLEY 2 OAER LEWI. 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E• EROSION CONTROL PLAN & LID IMPROVEMENT PLAN P56250 220215TH STREET - RS4T ANACORTES, WA _ -uric, PLAT OFMSNORTH' • ¢vs I.G 'AZ Totaz2CT7 .� _ . . .__ — - — - - -- - ---- - _ .. _..._. 1 of 2 • .1;s fi i'r1& D=E:.GAL DESCRIPTION: ?'% :•APT ifi.L' of for '7. .4LONG PATH Au OF LOTS 18, I Az Q AVD 20, C% &eve 206, AS Par SIR FY RECORDED .- •- • •. J. i,&? .:.IJ:':r4'S F'LE it'.11JBER 200303170356, RECORDS _ _ I A \ ll I . U 6 Ii \ T RV • or S'-'.45!' COUNTY, 574:t OF NASHINGiCN. v.L.• '- .-r, . , 31,1PC233'SILT FENCE ,- . ;.1 PERNETER SILT FENCING GENERAL NOTES TO PROTECT DOWNSTREAM PROPERTIES CPR' . __ _—_ I.yA�ADW�O GENTRY -c;se • • E•I¢ EI ORREJhGTOV, WA • MVJJ . - 1-CSIM-75S-•se:i ALLEY �. 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S•CLxAI:1 -,am•• tan a, 11 n,a wt.<I.< 7.D'� / 1a473 . _7.55 1. - I._ •--1 T.•:' VAC.01.h1 t 41,t1 m.vw own l vs a PC". lT4G /-'�� • Pf et ? Arnow B!AP C233 tfi1LCH sa 11.,a - / - " w:w1 ?POPERY BOURVV ARY yp SILT FENCE I BTAP G72T R i r A1G rrN1D r , 1`7JJ Si Ia:Ai) 1 - I I ,3,n°�cl.0 •SOILS'TGCIWP rat s - . CMRtY,M LOCATON OIOAS ` A -' ' (COVER YAW1 :N, S,. .-.... - , ......,•..I.....>.n,rr.S....T.,,. , I • OLAS=MIRING •`.,, •�.:�... .,.•,.. _,- ... s•=....1 I• STORM EVENTS. -- = BMP C1OS:STABILIZED- - . ....• ..••....-I.,� •'. •• -,.y,. �...,,•.. ! :.AN'1RUCRON •• I 8MPCV3:PLACI - ( FLIP „• •_. t . ...,n. - Iert n- ENTRANCE 1 >•r r COVE91NC1 3 ID TO l�'1" • \ .'1inY N.W' • . . -•.r..•• #-I a-.....,.- .- - n , .G • -f •• .. 4 Ti G-21:MU1•C . Y— rt c • ,[, • �.t t! a S-rb H.•II f..T1•s�.-h.l M'J.rr• --" I ',Zvi I s•Y+.i�..•i.-. ..f.•'IY..fi%^M1J'•V'NvYR•hY �' . _' _�.�•..—. GRAPHIC SCALE 1 , �~' anew. ...^.. _ - It,^ •ry:, YO 0 5 f0 80 - > h••: BAP CIG3:HIGHVISSBLITY ' _ - — -- - - -• ( /N &Le J PIAS.TiCPg1:C- . - j •` • _ Nona Semis: I J+rl. 10 Feet t REDUCE RISK OFPUBUC CONLttt.t DRIVEWAY / sra-avi7' ENTRY INTO CONSTRUCTION SURFACE TO BE CROSS SUP C107• HwF •slewry PADILLA ADLI r]:F Do- P"..J,BTIC PENCE .r!'L 119.-VAS.',11 Sire SLOPED I%AMNMUM TO TO REDUCE FISA •OF PUBLIC ' _ pRpA(pTe NOFFTOBEI - .:R%ciNTO.CON5,RUOTION — —• -- ---- - - - 3-CAR GARAGE CENTER - 15TH STREET I PERBED ONT3d63�hrlf F•- sir ate EARfi. - L4wNILANOSCAPEAREA- OSfO CONTROL _ & UD IMPROVEMENT PLAN .T.7.E, - P56250 2202 15TH STREET • • -' .. . _ ANACORTESI WA`a DLAT OF'4 NORTH' C7nAG - LG r •_ ; -. ._ . w:'L.- .rwtV xt aa7rur ._� "r 1 of 2 HOUSE-WWHM VIEWS AND REPORT 1.1/W1-3!;1 3 wv. r St4ose2 fJe E : in ew -ie;p r, r----- , I' , • , Ali - - 1 1--ge,03:'-'- 'i 1 1, , . _,.- ', ' I tim 1....1.7.7.. L .„:71 ....1517 !_•tiiiiiii.41110 ,, ,..._., , ,, :1 .% •-i. q-if; Basal I Precleveloped SCENARIOS l' .a.. , . ......„ ; Subbasin ame.M lemsin I , , : , --J Surface Intel-flow Groundwater —II ' Flovr To : E 1 I ,... -I L_ ivirtgated Area in Basin 54 ;Show Or!ly Seledad Run scenario : i Available Pervious Available Impervious .... .FrJFMFwTc.....li 8,70;ie-it.Kiii I l377 ....- ,71 ROOFTOPS/FLAT I :0 a ISM,i--Aiii . I , I Tr I. Num 1 wm i I I] Move Elements PerviclusTotet TC177-7 Acres impervious Totei p . Actes I: Basin Total 513'17- - •---—3 Acres ,. ... . Save xyi Loa:1)w t 4 Il• sr' 12 — --] . 1 Deselec Zero Select BY" GO — -..... ____. i27/2017 3:17 PM _ _ 4-46 : - At , 0 w i P 31 ..1i1P ,-,.. ' - 1 b' W .13 v1 07 n'-3i ,:„se2 i e Ezt Ve=•. e::� 1 `-" ale.. �. I D is r $' � '1ug SCENARIOS ,.. : '' —�--! r Subbasin Name. :Beam 1Qas>gnr�teas Bypass firPQC i Predevelo}�ed I Surface Intertiow Groundwater • Flows To : 'GravelTrencttBed7 _ . 1Giavei Trench Bed 1 .r.•.'_-r.Ii_.__.—__.._ Elty -, - I i. - s Area in Basin Fr. Show Only Selected Run Scenario - Available Pervious Available ImEetvious _.- I id C,Farettt Flat - rQ -v ROaFTOPS FLAT -— - , „cif F! FMFNTfi - - - - - — - -- - aion maw 1 ....re, i 2:1111:73 j ., ,ffligRIZ i i., , , I flit i 1 1 1 I 1 Move Elements 1 4Ji PervinusTota ! Acres Impervious Total IT ^T' Ams *?:.� .. I Basin Tote1 !0.077_-__ --1 Acres L. f 3eve xy i Lotto xy:' 1 41 iv f k :I _ i `_,76 Deselect Zero Select Bv- GO . .— -- 1 Wi, t3 trw),,��13' ute2 . . .'p EC?: 1.eic, Z cr :4e3c dN7-iiill iff..1.r .r�F...olirlibill— ID 1s/7'anPn.lti.:S ..ter9'S.:+it+/{Y+.C-....Al+�.�,e+ .�.T^Z�.,ti-....- ....�.�.v �.....•�...,. .. • _t_ _themati i ty 1t i ' 1 .. . SCE NAIL IOS ( --� — ' i! Facility Name Grnvel Trettclt Bed 1 p i _..' Outlet t Outlet 2 --.1 Outlet 3 �Prsde++efo sd Downstream Connection o l° _ . ��._,_.___.—.___ SP . _ _ _ f Facility?Type 'GravelTrench/Bed •• PreaprtenoitAppitedto Faoidy _..._Quick Trench �l 1 Rut,Scenario r s Evep©rtitm Ap1lled to FScIITY Et FMFNTS Facility Bottom Elevation(ft) t" imi.... E Facility Dimensions Outlet Structure Trench Length 46 alliiii11114 Width Trench Bottom g Riser Height((t) 1 --_ 1-z— - s Effective Total Depth .g' RiserDiametsr(in) 112 -� ENE4112;1 ____ Bottom slope of Trench ;O,00D0G1 RiserType ;Flat w-_-1 Ty a,1 Left Side Slope 0 Notch T e { � Right Side Slope ° Material Layers for TrenchlBed Layer 1 Thickness(ft) .2 Orifice Diameter Height QNlax Layer 1 porosity i033 Number (In) (Ft) (cfs) Layer 2 Thickness(ft) :° 1 IF.---•:j l0 =.1 0 _ 0 '-f Layer 2 porosity 2 in � � a ' j0.p Layer 3 Thickness g ;0 3 ,�—-:-1 IF—. 0 Layer 3 porosity ',Q I r Trench Volume at Riser Heed(acre-ft) .001 Move Ek meritslnfilb dtlon YES e-- . Pond increment 0.10�--:--1 Measured Infiltration Rate Gn/hr) )6.33 " ----- ---- `I Show Pond Table OpenTobie •-f �i Infrttration Reduction>=ector(infinactat) 'LT—'� e s i' Use Wetted Surface Area(sidewalls) IyES :-1 ®., Total Volume lnfilirated(acre-tf) 6.807 Tote!Volume Through Facility(s e-1 i 6.807 i Save xy t sled xv j ; .,.....t Total Volume Through Riser(acre-ft) 0.001 Percent Infiltrated 100 Ri3 'it S lir ) o yprirr W 3 p 31 ell _ Western Washington Hydrology Model PROJECT REPORT Project Name: wwhm3House2 Site Address: City : Report Date : 9/27/2017 Gage Burlington Data Start 1948/10/01 Data End : 1999/09/30 Precip Scale: 0 . 83 WWHM3 Version: PREDEVELOPED LAND USE Name Basin 1 Bypass : No Groundwater: No Pervious Land Use Acres C, Forest, Flat . 077 Impervious band Use Acres Element Flows To: Surface Interflow Groundwater Name Basin 1 Bypass : No Groundwater: No Pervious Land Use Acres Impervious Land Use Acres ROOF TOPS FLAT 0 . 077 Element Flows To; Surface Interflow Groundwater Gravel Trench Bed 1, Gravel Trench Bed 1, Name Gravel Trench Bed 1 Bottom Length: 4 6f t . Bottom Width : 2ft . Trench bottom slope 1: 0.000001 To 1 Trench Left side slope 0: 0 To 1 Trench right side slope 2: 0 To 1 Material thickness of first layer : 2 Pour Space of material for first layer : 0.33 Material thickness of second layer : 0 Pour Space of material for second layer : 0 Material thickness of third layer : 0 Pour Space of material for third layer : 0 Infiltration On Infiltration rate : 6.33 Infiltration saftey factor : 1 Wetted surface area On Discharge Structure Riser Height: 2 ft. Riser Diameter: 12 in. Element Flows To: Outlet 1 Outlet 2 Gravel Trench Bed Hydraulic Table Stage(ft) Area(acr) Volume(acr-ft) Dechvg(cfs) Infilt(ofe) 0.000 0.002 0,000 0.000 0.000 0.033 0.002 0.000 0.000 0.014 0.067 0.002 0.000 0.000 0. 014 0.100 0.002 0.000 0.000 0.015 0.133 0.002 0.000 0.000 0.015 0.167 0. 002 0.000 0.000 0.016 0.200 0.002 0.000 0.000 0.016 0.233 0.002 0.000 0.000 0.017 0.267 0.002 0.000 0.000 0.017 0.300 0.002 0.000 0.000 0.018 0.333 0.002 0.000 0.000 0.018 0.367 0.002 0.000 0.000 0.019 0.400 0.002 0.000 0.000 0.019 0.433 0.002 0.000 0.000 0.020 0.467 0.002 0.000 0.000 0.020 0.500 0.002 0.000 0.000 0.021 0.533 0.002 0.000 0.000 0.021 0.567 0.002 0.000 0.000 0.021 0. 600 0.002 0.000 0.000 0.022 0. 633 0.002 0.000 0.000 0.022 0.667 0.002 0.000 0.000 0.023 0.700 0.002 0. 000 0.000 0.023 0.733 0.002 0.001 0.000 0.024 0.767 0.002 0.001 0.000 0.024 0.800 0.002 0.001 0.000 0.025 0.833 0.002 0.001 0.000 0.025 0.867 0.002 0.001 0.000 0.026 0.900 0.002 0.001 0.000 0.026 0.933 0.002 0.001 0.000 0.027 0.967 0.002 0.001 0.000 0.027 1.000 0.002 0.001 0.000 0.028 1.033 0.002 0.001 0.000 0.028 CO 01 01 O O ri c-i N N 01 01 cr LC] C0 lD VP I-` r- OD CO CT 01 CD C7 rl c-3 N N co 01 0) cr car Ln ul i0 U0 r r co O CN 01 O O r-1 r1 r i N N C1 M 41 cr Ln N N N 01 ( ) 01 Cr) C) ('? t'') 01 C') C) 01 () C) CM 01 m (') 01 C') C) 01 cr sr yr cn err Sr cr cr v' 'fir cr . er cr 'C' .44 KI+ cr Lf) U) Ln Lfl L11 L() u) Ln Ln U) L11 U1 O 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 CD 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 CD CD CD 0 0 0 0 CD CD CD CD CD 0 0 CD Ca CD0 0 0 CD Ca CD CD CD CD 0 0 0 0 0 CD 0 0 0 0 0 0 0 0 0 O O O O O O Q o 0 0 O O o O O O O O O O 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 CD 0 0 0 0 0 0 0 CO CD cr 01 rs CO rH O N OD LC) (') M cr k.LD rn r-I 41 LID CO CZ\ 01 O U1 N O O O CD 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 L) VP O r cD r- 01 'V O r- CD lD N co cr C31 Lf) N O o O rH r) c0 O Ul .--+ CD O 0 000000000000000C? 0O0000C) 0000Orl01nrlD ODom kfD aD ,4 .rrrH crrriuo0101r- ,4U) crO0/ r • • • • • • • • • • . • • • • • • • • • . • > • • • • • • • • • • . • 0 • • a • . • a ■ e • . O 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 ri r H ri rH N N N 01 ^) ('") do c' v' LC) LC) l0 up lD N r CO CO rl rH r i r1 r-1 r-♦ H H H r♦ r) rl rI r1 r-I rl r1 rl H ri rH H rf ri H r1 r-1 N N N N N N N N N N N N N N N m C') 01 C/ C'') 01 M 01 C'') C') 07 (') C'') 0 0 00 O 0 0 0 0 0 0 0 0 0 0 0 0000000 000 0 0 0 0 0 000 00000 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 000 O O O O O O O O O 0 0 00 0 0 0 0 O O O 0 O O 0 0 0 0 0 0 0 00000 0 O 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 O O 0 O O C• 0 0• 0 0• 0 0 0 0 0 0 0 0 0• CD O O• O• 0 CD 0 0 Ca 0 CD 0 0• CD 0 0• O• 0 o• O• O• O• O O 0 0 0 0• 0 0• 0 0 CD 0 0 0 0 0 N N N N N N N N N N N N N N N N N N N (NI N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N O 0 0 0 O O O O 0 O O O o 0 0 0 0 0 0 0 0 0 0 CD Ca 0 0 0 0 0 0 CD 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 O O O O O O O O o 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 CD • a e • • a • • e • > e • • e • a r • • a a • O CD 0 0 0 0 O O O O CD 0 O CD O O O O CD Ca 0 0 0 0 0 0 0 0 0 0 0 0 0 0 o Q O O O O 0 C1 0 0 0 0 0 O C3 0 0 0 0 0 0 O O N O C') r O 01 N Ca CY) N co co r 0 (') N O CY) r O C') r O (') rN O 01 N co C') N co C ) r O 07 r O (') N O 01 N O Cr) N O Cr) r O (') r O (1) N C) C ) V) O01VPOMlQOm VaOCi) tiDOCi) wOC1UDOC') t) 0C') 5.0 CD 01 Oc'1toOC1upO01CQO01u0OCi) .PO01lDOmtiDO0/ VC) O01tDOC') O t-I r{ r-I N N N C') 01 (i) cr cr cm u1 LC) U7 l0 LD lD N N N co CA co 01 01 01 O O CD H r•-I H N N N C') C') 0) 'cs' .cri sr 1-() L() L() L0 LD UP N N N CO CO CO 01 01 ri c--1 c-•I ri r-i r♦ r! rl H r-I r4 r-I r-I r-s H H H ri r-I rH ri H rt rl r♦ rl ri r1 01 04 04 04 04 04 N N N 04 04 01 04 01 N 04 04 01 01 N N N 04 01 04 04 N N N 2.967 0.002 0 003 9.256 0.055 3.000 0.002 0. 004 9.739 0.056 MITIGATED LAND USE ANALYSIS RESULTS Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(ofs) 2 year 0.0007 68 5 year 0.001605 10 year 0.002242 25 year 0.003085 50 year 0.00372 100 year 0.004346 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0 5 year 0 10 year 0 25 year 0 50 year 0 100 year 0 Yearly Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped _Mitigated 1950 0.003 0.000 1951 0.002 0.000 1952 0.001 0.000 1953 0.001 0.000 1954 0.000 0.000 1955 0.001 0.000 1956 0.001 0.000 1957 0.001 0. 000 1958 0.001 0.000 1959 0.001 0. 000 1960 0.002 0.000 1961 0.001 0.000 1962 0.000 0.000 1963 0.000 - 0.000 1964 0.000 0.000 1965 0.001 0.000 1966 0.001 0.003 1967 0.000 0.000 1968 0.001 0.000 1969 0.002 0.000 1970 0.000 0.000 1971 0.000 0.000 1972 0.002 0.000 1973 0.001 0.000 1974 0.000 0.000 1975 0.002 0.000 1976 0. 007 0.000 1977 0.000 0.000 1978 0.000 0.000 1979 0.001 0.000 1980 0.000 0.000 1981 0.001 0.000 1982 0.001 0. 000 1983 0.002 0.000 1984 0.001 0. 000 1985 0.002 0. 000 1986 0.000 0. 000 1987 0.001 0. 000 1988 0.001 0.000 1989 0.002 0.000 1990 0.001 0.000 1991 0.001 0.000 1992 0.002 0.000 1993 0.001 0.000 1994 0.001 0.000 1995 0.000 0.000 1996 0.000 0.000 1997 0.001 0.000 1998 0.003 0.000 1999 0.001 0.000 2000 0.000 0.000 Ranked Yearly Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.0067 0.0034 2 0.0029 0.0000 3 0.0029 0.0000 4 0.0024 0.0000 5 0.0020 0.0000 6 0.0020 0.0000 7 0.0019 0.0000 8 0.0017 0.0000 9 0.0017 0.0000 10 0.0016 0.0000 11 0.0016 0.0000 12 0.0015 0.0000 13 0.0013 0.0000 14 0.0012 0.0000 15 0.0012 0.0000 16 0.0012 0.0000 17 0.0012 0.0000 18 0.0009 0.0000 19 0.0009 0.0000 20 0.0009 0.0000 21 0. 0009 0.0000 22 0. 0008 0. 0000 23 0. 0008 0. 0000 24 0. 0008 0. 0000 25 0.0008 0.0000 26 0.0007 0.0000 27 0.0007 0.0000 28 0.0007 0.0000 •tt a� 00000ao00000aCao0000000 cd Cl) m rn (i) Cl) Cl) Ca Cl) 01 Ca Ca cn U) cn Cl) Ca CI) U) Cl) 01 Ca Cl) U) cn o ® •c> o 0 0 C) o 0 0 o CD 0 0 C3 0 o 0 o CD 0 0 a laa (0 CZ ( (0 (0 ro (0 (0 c0 cG r0 c0 c0 (0 cti (0 CU ca r0 cO (U ro a0 (ct (0 al CDC000OoaooOCJooC30000nCD ® oo a, ga., w wQ+ waaa 0.4 c.: w wa, w wog wa, wc4a ta4 O4 Oa C7 0 ® C7 (D C) 0 CD o CD 0 CD o CD CD a © O C,) o C7 CD a b_ . . . . . . . . . . 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Cr) CO CO CO Cn Cr) U} fl (1) CO CA (4 of CO CA U) {!) cr) CO 0) CD CO CO CA tr gCS ca ro cti (CS rCS stl ct its (a al (o rC (11 b :U ro cZ (ti ra (0 MS Cd ci) ai cJ CO ct5 cC r[3 ctS rq cO CO cti r3 ro Cti c (0 CO al ro ti a, at as ai at al a, at a at a a a, a{ ai a t as a: al at al a C14 a LL; o4G, a+ al Oi dui Q2 a, ai a 0. aI w ca, a, a, a, w at Oi a O4 al a1 L 0, a O O O O O C3 O O O rr rl ri r-i ri ri rl r i r--1 rt ri rl N N N N N N N N N N N (N N CO CO CO CO CO CO c') (Yl .St :7t 'G' qv 10 to u1 u0 U) ul N N N N N N CV N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N N CV N N N N N N N N N N N N N N N N r^i CD CO r- r1 CO 1~ O O c.0 N CA r-I ri qv CO M lfl N t1 O O N N O al C- dt N O co N u i ul q' CO {V N r-1 O O -7' O dl C9 Q0 N OD 10 d+ N 01 N a' O O co co (0 rH O CO N lfl CO CO r t C31 C31 co co co C- C- N fn CO 01 CO N N N N N r I r-i r-i r1 ri r-1 ,-I C CO CO GO OD PN Q0 lP l0 to lfl 10 10 10 u1 Cs) 1f) V* ,r at qv 01 CO CO CO CO CO CO 01 Cn Can P 1 u) ul u 1 l4 Q0 QD r- C— r- m 03 CO 0) CT 01 O O O ri r~ r1 N N N 01 01 01 Q+ v+ a+ ].f) L11 U1 lrJ Up lfl r- r` r- O CO CO C N Ol Q1 O O O r A r-i r-1 c^i ri t-! rl r-4 r-i c-1 r 4 r-t cH r-I r-f r-1 r-I r-1 rt r-1 r-i ri ri N N N N N N N N N N N N N N N N N N CV N N N N CV N N N N N N on on CO CO CO CO O O O O O O O O O O O O O O O O O O O O O O O O O O O C3 0 0 0 0 0 0 0 0 0 0 O O O O O O O C3 0 0 0 0 0 0 0 0 0 0 0 O O O O O O O O O O O O O O O O O O O O O O O O O O O 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 O O O O O O O O O O O 0 0 0 o O O O O O c o O O O O O O o O c O O O O O O O O O O O O o O O O CD O O O O O O o O O O O O O O O O o O c O O O O 0 . 0032 36 2 5 Pass 0 . 0032 36 2 5 Pass 0 . 0032 35 2 5 Pass 0. 0033 35 2 5 Pass 0 . 0033 34 2 5 Pass 0 . 0033 33 2 6 Pass 0 . 0034 33 2 6 Pass 0. 0034 32 0 0 Pass 0. 0035 31 0 0 Pass 0. 0035 31 0 0 Pass 0. 0035 31 0 0 Pass 0. 0036 30 0 0 Pass 0 . 0036 30 0 0 Pass 0 . 0036 29 0 0 Pass 0 . 0037 27 0 0 Pass 0 . 0037 27 0 0 Pass 0 . 0037 26 0 0 Pass water Quality MP Flow and Volume for POC 1. On-line facility volume: 0 acre-feet On-line facility target flow:: 0 cfs. Adjusted for 15 min: 0 cfs. Off-line facility target flow; 0 cfs. Adjusted for 15 min: 0 cfs. Perind and Impind Changes No changes have been made . This program and accompanying documentation is provided 'as-is ' without warranty of any kind. The entire risk regarding the performance and results of this program is assumed by the user. Clear Creek Solutions and the Washington State Department of Ecology disclaims all warranties, either expressed or implied, including but not limited to implied warranties of program and accompanying documentation. In no event shall Clear Creek Solutions and/or the Washington State Department of Ecology be liable for any damages whatsoever (including without limitation to damages for loss of business profits, loss of business information, business interruption, and the like) arising out of the use of, or inability to use this program even if Clear Creek Solutions or the Washington State Department of Ecology has been advised of the possibility of such damages. DRJVEWAYtaWWHMVIEWS AND REPORT 1 . j r40CDCS0CSC4 (400f400 0 0 CD 0 CY 0 C4 C4 0 0 Kr 0 4) es 0 0000ft: OOOOOUQ 0c) co 00C40 0000C4CSC4C40MO00CD 00CSC4C: 1 in0to0OOO CDOC? Ca4O0CS 004SC4C400CIC4C4CY00 A0C404.2 . ' • 1 0O0CyrC40C4 C7OOOC> OO <4OC) C9OC4C4OC) OC) C} CaC] 0C;) C) O C: . . i C? 0 0 0 C) 0O C? 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L, sa N w N Nd Q,i rinia E04,3 ^r >a +d • • M >i •-r m% cS . i fal r1 st` rn w 1 PO m CD rr N C 1 +i' rn a po rrr a ri <V a 0 • • a. al DO - 41 IP un 10 10 10 U4 ►n 10 PO ► i et1 4Q un <w 4A MO w .c+ �+ .4i 0n t- r, t- r- ram. mii ') 1J q >0 >0 0 Nm4rt mmmmmmrslmono>, rnmmaDmolmmm a4sim4+ 4maa- 0 lei 04 C) !$I G) O • re .•1 rl ri r1 rt 1 rl IA al rl 64 rl r 1 rl r1 rl al r 1 ■ I rr ■ 1 r I r$ r1 i [•r rn o M rt N M .•4 a. r :� _:: : .:.��..?:.��..� :�:�L:Tci_r�T�'iT[C:l�sYS44CJ 1T�- -'lLi�l^!rJt�4.C`•-L. -.� : •.i_:� �r 7 g 1 Fr 4a. 9 m jei • / , • m / lO no. o CP 4• 1 1 x 4 C 0 eitii i x , 0 CP VIP x sci 2 ' iSs g II x d • C° _ y' 0- 13 C 1 I' x a I -° 3 3433t E- rrim ►; x a4 c) LL NI/ i . 4- a x c) 4 pc1 Q 1 - " 40 o ■ i a IC rr: 1 1 .G _ � 1 I c Co !o I i ' • p "' • x °� • m v I MI I ' X eI ismp l� '� R I 0 I x c dY. cn eg I x a d CP a, a x �° � I 1 leik 'Ns ei ti � ✓ X i" 4 ;�, r� cm � � , tri-7: , i. i x <, cvI is •aI It ail n 0 I� 1 Cil_ 0 0 m w CA 4) rlJr t . W C I- di ° t Ca taP btc 'S •Isr 1 Ill 4 i csi.co "Ac.)-1.=.1 03 0 4 G. 0 a I Wrt?M3 drnvevayz - ite Erit Vey:: -lei; illtilmil i FIOTI 11 ' .. .711111M11111- ' 11 II L1101111 . ...._.. ..,.,,_may..,_.. .•,...,.�.��-:*_,:::-:.z......_F,,,..,.....,r.�..._.--...._�..y..._a_.-_�.._.,._..._.,-. , a.._....,.a-_.._.... ...._.r...._.. � ___ ..,.-_, _ , il ~�+rs;. - -.-___ l P001 PradeIII +►�faped f �iT`._ ..__ . . acy .._._.._._ --° 12,=WItMTS.) 0 0801 10E 1 801 PQC 1 Mitrgteted flea : d.,- 08"_ 2 Year s 0.0003 0.0064 _� ..s ?tar ® 3.000E 0.0088 n_0 Yea: ® 0,0008 0.0106 ,23 :ea; O .wOi "v.0_3i tk 10E 0 i'SO Year a 0.0014 0.0150 s. [120, 'Tied s 0.001.S 0.0171 0 ' 1949 0.0010 0.0060 j 101`1 . 11}a0 0.0006 0.0060 ,; 1331 0.0004 0.0072 F; 1192 0.0003 0.005s µ 1993 0.0001 0,0061 I 2354 0.0002 0.005 illE-2 = i 136. 0.0202 0_0039 1 10 20 c30 4a ., ,...u^£ 3'=` Cfr•` 90 09 ;913aa 0.0003 0 .0039 ' H d ive rronability 1957 0.0:004 0.0084 1998 0.0002 u.Ce38 Durations mow prequert j�rVr skew( UQ nl' HYilro9raph !'�NetlandFluch�ation 111 3369 0.0006 0.3041 11990 0 0303 0.0084 Analyze detwetFs ii 1991 0 0002 0.2030 __ � ,W,._ - � !I 13 G 0.s0000 0.0075 �1 PUYAl1.UPCIAILYEVAPI+�IJEf�1SEIV-}�JSE ;; 1343 0_"t0002•:2 0.0033 2BURUNGTOI�IPREOP ii _363 v 0 0 .0016 ii :365 0.0005 0.0174 1000 Gravel Trench Bed 1 AU.OUTLETS Mitigated :.3 5 6 0-pool v.0049 '1001 Gravel Trench Bed OUTLET 1lt+ldrgated . .35; +3,00v3 0.0 11002 Gravearench Bed 1 OUTLET 2 Mitigated -1968 7 0.00 3 0.0098 122 i Ion Gravel Trench Bed 1 STAGE Mitigated fit es rr 1989 0.0c03= 0.0039 l.___ _ _��..,.! ., 19�+v 0.0001 0.0125 An D nsBts F 1, Stage PrsSi� EVla41 EaOr`r 1 t ..9�'"'. t' .0007 G.0081 Flood Frequency Method 11 .912 0.0003 0.0047 • Log PeaISEWIT :181017B it �g?3 0.0002 4.00'-s ,r f Wetbull • ;74 n ?;{'.'3R ^ '!^?�Ai it 1 t. Otrttl$Ir@ _ -- -- - t WWHM3 dr!v'2way2 ;le Edi: Vie' '-'e r .,„.7i 1 ri. ..,. ..e.„ Ills 11: 1,____-----: :15%° r11141110:1 1111411.1; - _ `' • .':=asr, I r tfrcetea. SCENARIOS - -- -- - Subbasir Mame: Eesin '! -1 '- Designees as 6ypnes far FGC ,...=:acev*!ce_ -- : Surface InterBow Groundwater Flows To ' , �..-... :` - --- - - • 0. Mitigated Area in Basin W thaw Only Selected Run ScenMo — i Available Pervious Available Impervious Fl F3ut FNTS111 si >~orest Rc� E Roof FLAT - ; ig- - Fo oR/EciAYs r fliia II it ..101.1. j1.0.1,,,,4 inn , MEW 0 E Mcry El ineritt: , 4: _____ J_ _ Perv9ouaTote 0 ' Acres IrnpaiviousTatai 10.02B 7 Acres 411 _lir L-. Basin-total lQ b2B ........ __ ....1 acres t eve x.v LO®d)W 4 ®` d •1 rf Deselect Zero Select BY- GO t o � 1 littN:-1;M3 h•:re►.ayz -4. -4w* •.0.4 44; „w !e Ea <ie- .,eir 1 fGT ® tip . - 71 110' • Eg .1.I L.il I ,, , 1017-11i°11pi:! 4111t,r0.1 : :. 1 -Ist _ f�' I r- • _�I— i e" '�96II I Mitigated SCENARIOS I. I: i Subbasi?i Name: Basin 1 [ r Destc3nale as Bypass far POC- 1; `-I1 =redeveloped i ' .G Surface Intarticrw Grtundwetar • Area in Basin P. Show OnlySelected i Run Scenario i. Available Pervious Available Impervious - Fi FMFNTS '` FvresL Flat ; 3D_ pr R40FTOPS FIAT : r tom► l DRIVEV/AYSF1.AT r028 wt,. ffl ii Elm i' ..4:. li I :,„ : 1 dRii....7i5 !VI il ; ., I .),,.:7 ,I i 1 t 1 DLiii.-4 'i ; .: II i; ., i 1. I1l i 1 '# SI { 3 1 Move Elements 4li ^ PerviousTota Acres Impervious Total 0.828 Ames 411 � 301 r. • - Basin Tole! b 028_ ____�Acres save x.y Load xy} ► o! +I :40 r•"I. .__.I Deselect Zero Select BY: GO Western Washington Hydrology Model PROJECT REPORT Project Name: driveway2 Site Address : City Report Date : 9/28/2017 Gage Burlington Data Start 1948/10/01 Data End : 1999/09/30 Precip Scale : 0. 83 MOM Version. PREDEVELOPED LAND USE Name Driveway Bypass: No GroundWi ter: No Pervious Land Use Acres C, Forest, Flat . 028 Impervious Land Use Acres 1 Element Flows To: Surface Interflow Groundwater Name Basin 1 Bypass: No Groundwater: No Pervious Land Use Acres Impervious Land Use Acres DRIVEWAYS FLAT 0 . 028 Element Flows To: Surface Interf low Groundwater MITIGATED LAND Unr ANALYSTS RESULTS Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0. 000279 5 year 0. 000584 10 year 0.000815 • 25 year 0.001122 50 year 0.001353 100 year 0.00158 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfa) 2 year 0. 006393 5 year 0. 000842 10 year 0. 010627 25 year 0.013072 50 year 0.015036 100 year 0. 017125 Yearly Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1950 0.001 0. 008 1951 0.001 0.006 1952 0,000 0.007 1953 0,000 0.007 1954 0.000 0.008 1955 0.000 0.006 1956 0,000 0.004 1957 0.000 0.004 1958 0.000 0.008 1959 0.000 0.006 1960 0.001 0.004 1961 0.000 0.008 1962 0.000 0.005 1963 0.000 0.008 1964 0.000 0.004 1965 0.000 0.008 1966 0.000 0,017 1967 0.000 0.005 1968 0.000 0.012 1969 0.001 0.010 1970 0.000 0.004 1971. 0.000 0.012 1972 0.001 0. 007 1973 0.000 0.005 1974 0.000 0.006 1975 0.001 0.006 1976 0.002 0. 012 1977 0,000 0. 009 1970 0. 000 0,005 1979 0.000 0. 010 1980 0.000 0.005 1981 0.000 0.007 1982 0.000 0.005 1983 0..001 0.006 1984 0.000 0.005 1985 0.001 0.007 1986 0.000 0.007 1987 0.000 0.005 1988 0.000 0.004 1989 0.001 0.011 1990 0.000 0. 006 1991 0.000 0.007 1992 0.001 0.010 1993 0.000 0.006 1994 0.000 0.004 1995 0. 000 0.005 1996 0.000 0.005 1997 0.000 0.008 1998 0.001 0.014 1999 0.000 0.007 2000 0.000 0.004 Ranked Yearly Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.0024 0.0174 2 0.0011 0.0144 3 0.0010 0.0125 4 0.0009 0.0122 5 0.0007 0.0116 6 0.0007 0.0108 7 0, 0007 0.0103 8 0.0006 0.0102 9 0.0006 0.0098 10 0.0006 0.0088 11 0.0006 0.0084 12 0.0006 0.0684 13 0.0005 0.0081 14 0.0005 0.0080 15 0.0004 0.0077 16 0.0004 0.0076 17 0.0004 0.0075 18 0.0003 0.0072 19 0.0003 0.0072 20 0.0003 0.0072 21 0.0003 0.0070 22 0.0003 0.0069 23 0.0003 0.0067 24 0.0003 0.0067 25 0.0003 0.0066 26 0.0003 0.0064 27 0.0003 0.0062 28 0.0003 0.0061 29 0.0003 0.0060 30 0.0002 0. 0058 31 0.0002 0.0056 32 0.0002 0.0055 33 0.0002 0.0055 34 0.0002 0.0055 35 0.0002 0.0054 36 0.0002 0.0053 I 37 0.0002 0.0052 38 0.0002 0.0052 39 0.0002 0.0050 40 0.0002 0.0049 41 0.0001 0.0047 42 0.0001 0.0047 43 0.0001 0.0046 44 0.0001 0.0044 45 0.0001 0.0041 46 0.0001 0.0040 47 0.0001 0.0039 48 0.0001 0.0039 49 0.0000 0.0039 50 0.0000 0.0039 51 0.0000 0.0038 POC #1 Facility FAILFP duration standard for 1+ flows. Flow(CF3) Predev Dev Percentage Pass/Fail 0.0001 4538 36765 810 0.0002 3991 35393 886 , , 0.0002 3462 34154 986 J. 0.0002 3061 33225 1085 Fain 0.0002 2733 32281 1181 Fail 0.0002 2468 31334 1269 iI 0.0002 2212 30350 1372 II 0. 0002 2005 29487 1470 0.0002 1821 28647 1573 :ail 0.0002 1654 27838 1683 vdil 0.0003 1490 27078 1817 ail 0.0003 1365 26465 1938 ! ail 0.0003 1243 25884 2082 Dail 0.0003 1118 25379 2270 Wail 0.0003 1025 24780 2417 Vail 0.0003 930 24234 2605 1 0.0003 857 23702 2765 0.0003 798 23211 2908 0.0004 744 22710 3052 . 1 0.0004 696 22223 3192 ail 0.0004 646 21780 3371 Fail 0.0004 602 21311 3540 "all 0.0004 554 20788 3752 Hail 0.0004 510 20332 3986 tail 0.0004 475 19925 4194 Fail 0. 0004 439 19473 4435 Gail 0. 0005 401 18959 4727 Fail 0.0005 371 18584 5009 Pail 0.0005 346 18280 5283 Vail 0.0005 325 17918 5513 Fail 0.0005 307 17569 5722 Fail 0.0005 291 17265 5932 c,aii 0.0005 273 16903 6191 lail 0.0005 247 16568 6707 F'iH 0.0006 220 16255 7388 F'ai ': 0 .0006 200 15955 7977 F. , . 0.0006 187 15678 8383 0.0006 172 15392 8948 Fail 0.0006 158 15106 9560 Pail 0.0006 152 14829 9755 Fail 1 0.0006 142 14578 10266 Fail 0.0006 134 14270 10649 Flil 0.0007 128 14037 10966 it 0.0007 123 13791 11212 1:'a11 0.0007 116 13546 11677 Fail 0.0007 112 13291 11866 Fall 0.0007 105 13036 12415 Fall 0.0007 100 12795 12795 Faa.]. 0.0007 94 12540 13340 Fail 0.0007 90 12258 13620 Fail 0.0008 89 12084 13577 Fail 1 0.0008 86 11883 13817 Fail 0.0008 86 11641 13536 FaiI 0.0008 82 11386 13885 Fall 0.0008 78 11149 14293 Fail 0.0008 75 10957 14609 rail 0.0008 74 10756 14535 Fail 0.0008 72 10577 14690 Vail 0.0009 69 10407 15082 Fail 0.0009 67 10246 15292 Fail 0.0009 64 10085 15757 Fail 0.0009 60 9893 16488 Fail 0.0009 60 9710 16183 Pail 0.0009 58 9500 16379 Fail 0.0009 56 9330 16660 Fail 0.0009 54 9133 16912 Fail 0.0009 53 8941 16869 Fai.' 0.0010 51 8816 17286 Fai ' 0.0010 50 8686 17372 Fa i " 0.0010 48 8588 17891 Fail 0.0010 47 8472 18025 Fail 0.0010 46 8351 18154 Fail 0.0010 43 8221 19118 Fail 0.0010 43 8114 18869 Fail 0.0010 41 8002 19517 Fail 0.0011 39 7908 20276 V-i1 0.0011 39 7792 19979 0.0011 38 7667 20176 it 0.0011 38 7586 19963 0.0011 38 7488 19705 Pail 0.0011 37 7403 20008 Fail 0.0011 37 7327 19802 Fail • 0.0011 37 7233 19548 Fail 0.0012 36 7157 19880 Fall 0.0012 36 7023 19508 Fail 0.0012 35 6938 19822 � ! ' l 0.0012 35 6840 19542 r :ai1 0.0012 34 6750 19852 Fa i I 0.0012 33 6665 20196 Fal 0.0012 33 6576 19927 Fail 0.0012 32 6509 20340 Fail 0.0013 31 6420 20709 Fail 0 0013 31 6317 20377 0 . 0013 31 6227 20087 0 . 0013 30 6156 20520 0 . 0013 30 6084 20280 0 . 0013 29 6013 20734 0 . 0013 27 5937 21988 0 . 0013 27 5874 21755 0 . 0014 26 5816 22369 The development has an increase in flow durations from 1/2 predeveloped 2 year flow to the 2 year flow or more than a 10% increase from the 2 year to the 50 year flow. is Water Quality PMP Plow and volume for POC 1. On-line facility volume: 0 acre-feet On-lie facility target flow: 0 ofs. Adjusted for 15 min: 0 eft. Off-line facility target flow: 0 of's. Adjusted for 15 min: 0 cgs. Perind and Imp1nd Changes No changes have been made. This program and accompanying documentation is provided 'as-is' without warranty of any kind. The entire risk regarding the performance and results of this program is assumed by the user. Clear Creek Solutions and the Washington State Department of Ecology disclaims all warranties, either expressed or implied, including but not limited to implied warranties of program and accompanying documentation. In no event shall Clear Creek Solutions and./or the Washington State Department of Ecology be liable for any damages whatsoever (including without limitation to damages for loss of business profits, loss of business information, business interruption, and the like) arising out of the use of, or inability to use this program even if Clear Creek Solutions or the Washington State Department of Ecology has been advised of the possibility of such damages SIDEWALK-WWI-IM VIEWS AND REPORT P:.Projects1170201DOCSIDrainage Memo 10.1917.doc 9 1 WWHM3 Sidewalk 'Be Edit %slew Help 179 . 111&4.47 imp . ii 4-7-e...* 1 -hh. Milli ... • 1-8- DFive:f.tk,P!'edeve:cpeo 11E111 SCENARIOS 11 . Subbasin Name* Driveway i 1 1 P 7,redeveioped 1: ; 4 Surface lnterflow Groundwater •i 1 1 ''' _ Flows To . I [1r Mgated Area in Basin 1' Show Only Selected • ,.; Run Scenri ao • , f:: Available Pervious Available Impervious i i.; d,FOreist: tt l'in F. iiobfor:. k:Af-. --' -6--- --- —F1 FMFMT.S ,., — . _..._. . .. . . .. .' 0111111111 F.; DRIVEWAYS FLAT I gr._ ,....._ I. ... , , , DE 1 i i, ,1 Move Elements 41 I 1 PetviousTote 0 011 4 Acres Impervious Tota _ l b ; Acres • —1,..4_ 4' ._ ____< __ __ _. ___., 1 Basin Total 1E011 Acres .... I Save xy! Load xxi 1 I 14 I Deselect Zero Select BY: GO _ lt—ip flo 02 1 pfi , IV _ _I - -- 1 WWHM3 Sidewalk - 'iie it View Heip ) 0 fil di '-' _ .............. . ,_, iim...-.4 rnii i ' i=Li .4.c.„:41.17. _____ ,. , ID . .. ......._..,..__._._ Bastn 1 Mated SCENARIOS I Subbasin Name: Basin 1 _ 1 I- Designate es Bypass for POD ,_- ,- r--- 1 lki; Predeveloped Surface Interflaw Groundwater I t Flows To : iL___. . • i r--- p .t.t.ec . --..----_-- Area in Basin 1 Show Only Selected • Run Scenario , i*i Available Pervious Available Impervious Fl FMFNTR ! .I 1- A/S,ForestFlet --- G .-...3• . .. -rEfoi-6 /FMf - - -- --1 :ti- -------i -- 11 VIM ----NB.Forest Mad - : D ROADS/MOD --1 10.... ._... .....__________. ...._.. . ! , , 1 r.N13,ForestSteep_ i 0 - ROADS/STEEP it:1 R III 0 _.. ..__.. ..._____. -- - --- - - - - 1-A/S,Pasture,Mod 0 fri k-ki FLAT n:OPS 14- DRIVEWAYS FLAT ,0 _. ____ _... . ._ ._.... ... . iii Willi Wilk , As:/fikiXtiitu-re,Siiii..)--.- 0 -- liFiii7fwAii,,46o :6 •• . . Ailk Lew- I,Flat : 0 liRIVEWAYSISTEEP in ................ . .... • ------ - . 1.awn,M ad -----* : 0 jV SIDEWALKS/FLAT '• . .. _ .. .._.__ . .... I r---- iiiv-n.Ste ep ,0 SIDEWALKS/MOD !O ----------- --------.- _ Forest Flat 1 10 SIDEWALKS/STEEP i0 ... ._.....__ •- i - 6,Forest Mod to r- -i-5-Aili1J NG/FLAT i 0 .. _ -- dFclre. st-' Stiee-p-- - 0 -- -15ATRKit;laimOD : !0 -- diDasturn,Rai 0 PARKING/STEEP ! 10 .._ _ . .... __ . C,Pa-aure-,Mod- _ : '0 - POND • xi , ........_______ _.... .. .. 6,-Fstu-re,S:teea 0 . ....._ . . - . . i _ __ . ......._, - C,Lawn Fled 0 --- C,[-Wirt Mod io - -- -- Move Elements .1 i 1 __...1 PerviousTota ',:?, ; Acres Impervious Total TOT-1-------1: Acres 46 ' 40.! .--i - ------- --4.•-_. V Basin Total 10.011 !Acres ..., . I Save xy f Load x.y ' 4 1 . I I, __..z)‹ "iiii• * I i Deselect Zero Select By GO ._ .. . . -- •./M Sidewalk Te Edf ievi r-e p 407 41:1V 1"+f01531 ® k di iii Analyst:, - J 11 501 FOCI Predeveloped1 i::lo:; F requein.,y 21 10E1 •• 801 POG1 mitigated flow i ?lo. (CPS) Pre-eveioped 14:tiyated 6.=___ - •• I,2 Yeas 0 .0001 0.0025 15 fear i = 0 .0002 0.0035 - ,100 -ear = 0.0003 0.0042 - r. 125 Year = 0.0 004 0.0051 0 10E0 50 Year = 0 .0005 v.0039 - -_-_ 3 i10.0 Yaa- = 0.0006 0.0367 �'early Peaks __._.- 0 II :949 0.0004 0.0331 - - j 10E-1 I 1950 0.0002 0. 023 L 11951 0.0002 0•. 0028 1952 0.0001 0.0026 1953 0.0001 0.0032 - `--I 10E-2 '! 1954 0.000t 0.0022 _.. .•--1 10 20 30 40 50 60 70 80 90 99 195a 0 . 0001 0.0015 Cumulative Probability A° 19�6 z 0.0015 �nna�o6oa�ap°°` ! 1957 0.0002 0.0033 ..s :1 1958 0.0001 0.0323 - - - Durations Flow Frequency __Water Quality 1 Hydrograph j WetlandFluctuationJ it 1933 0.0002 0.0016 1 1980 0.0001 0.0033 Analyze datasets '1 1961 0 .0001 0.0 019 to- 1 1, !i 1962 0.0000 0.0030 } .,N -.A-. I MO!' ' ii 1963 0.0001 0.0015 - 1964 0.0001 0.0030 it 1955 0.0002 0.0068 1966 0.0000 0.0019 1967 0.0001 0.0048 1968 0.0002 0.0039 1969 0.0001 0.0015 Acres a All Datasets Flow ta ge Predp tEvap -P0C1 J !' i9'?0 0.000a 0.Lev026 19?b 0 .0003 0.026 Flood Frequency Method I' 1972 0 .0001 0.0018 . Log PearsonTypelll178 19?3 0.0001 0 .0022 • Weibull ,1 1 o?d niZn, n n^99 " Cunnene ;l ! ,----.,. . Western Washington Hydrology Model PROJECT REPORT Project Name: Sidewalk Site Address : City Report Date : 10/19/2017 Gage Burlington Data Start : 1948/10/01 Data End : 1999/09/30 Precip Scale: 0 . 83 WWHMB Version: PREDHVELOPED LAND USE Name Driveway Bypass: No GroundWater: No Pervious Land Use Acres C, Forest, Flat .011 Impervious Land Use Acres Element Flows To: Surface Interflow Groundwater Name Basin 1 Bypass: No GroundWater: No Pervious Land Use Acres Impervious Land Use Acres SIDEWALKS FLAT 0 .011 Element Flows To: Surface Interflow Groundwater MITIGATED LAND USE ANALYSIS RESULTS Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.00011 5 year 0.000229 10 year 0.00032 25 year 0.000441 50 year 0.000531 100 year 0.000621 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0.002512 5 year 0.003474 10 year 0.004175 25 year 0.005135 50 year 0.005907 100 year 0,006728 Yearly Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1950 0.000 0.003 1951 0.000 0.002 1952 0.000 0.003 1953 0.000 0.003 1954 0.000 0.003 1955 0.000 0.002 1956 0.000 0.002 1957 0.000 0.002 1958 0.000 0.003 1959 0.000 0.002 1960 0.000 0.002 1961 0.000 0.003 1962 0.000 0,002 1963 0.000 0.003 1964 0.000 0.002 1965 0.000 0.003 1966 0.000 0.007 1967 0.000 0.002 1968 0.000 0.005 1969 0.000 0.004 1970 0.000 0.002 1971 0.000 0.005 1972 0.000 0.003 1973 0.000 0.002 1974 0.000 0.002 1975 0.000 0.002 1976 0.001 0.005 1977 0.000 0.003 1978 0.000 0.002 1979 0.000 0.004 1980 0.000 0.002 1981 0.000 0.003 1982 0.000 0.002 1983 0.000 0.002 1984 0.000 0. 002 1985 0.000 0.003 1986 0.000 0.003 1987 0.000 0.002 1988 0.000 0.002 1989 0.000 0.004 1990 0.000 0.002 1991 0. 000 0.003 1992 0.000 0.004 1993 0.000 0.002 1994 0.000 0.002 1995 0. 000 0.002 1996 0.000 0.002 1997 0. 000 0.003 1998 0.000 0.006 1999 0.000 0.003 2000 0.000 0.001 Ranked Yearly Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.0010 0.0068 2 0.0004 0.0056 3 0,0004 0.0049 4 0.0003 0.0048 5 0.0003 0.0045 6 0.0003 0.0043 7 0.0003 0.0040 8 0.0002 0.0040 9 0.0002 0.0039 10 0.0002 0.0035 11 0.0002 0.0033 12 0.0002 0.0033 13 0.0002 0.0032 14 0.0002 0.0031 15 0.0002 0.0030 16 0.0002 0.0030 17 0.0002 0.0030 18 0.0001 0.0028 19 0.0001 0.0028 20 0.0001 0.0028 21 0.0001 0.0027 22 0.0001 0.0027 23 0.0001 0.0026 24 0.0001 0.0026 25 0.0001 0.0026 26 0.0001 0.0025 27 0.0001 0.0024 28 0.0001 0.0024 29 0.0001 0.0023 30 0.0001 0.0023 31 0.0001 0.0022 32 0.0001 0.0022 33 0.0001 0.0022 34 0.0001 0.0022 35 0.0001 0.0021 36 0.0001 0.0021 37 0.0001 0.0020 38 0.0001 0.0020 39 0.0001 0.0019 40 0.0001. 0.0019 41 0.0001 0.0018 42 0.0001 0.0018 43 0.0001 0.0018 44 0.0001 0.0017 45 0.0000 0.0016 46 0.0000 0.0016 47 0.0000 0.0015 48 0.0000 0.0015 49 0.0000 0.0015 50 0.0000 0.0015 51 0.0000 0.0015 POC #1 Facility duration standard for 1+ flows. Flow(CFS) Predev Dev Percentage Pass/Fail 0.0001 4488 36649 816 Fail 0.0001 4018 35496 883 Vail_ 0. 0001 3498 34253 979 Fail 0. 0001 3071 33247 1082 Fail. 0.0001 2725 32259 1183 Fail 0.0001 2442 31262 1280 Nail 0.0001 2242 30480 1359 Fail 0.0001 2020 29568 1463 Gail 0.0001 1827 28665 1568 Nail 0.0001 1648 27797 1686 Fail 0.0001 1487 27069 1820 Fail 0.0001 1383 26532 1918 fail 0.0001 1252 25929 2071 Fail 0.0001 1120 25392 2267 Fail 0. 0001 1030 24798 2407 Fail 0. 0001 926 24221 2615 Fail 0.0001 864 23774 2751 Fail 0.0001 798 23242 2912 Fail 0.0001 748 22750 3041 Fail 0.0001 697 22236 3190 Fail 0.0002 643 21771 3385 Fail 0.0002 610 21369 3503 Fail 0.0002 560 20886 3729 Fail 0.0002 513 20368 3970 Fail 0.0002 476 19938 4188 Fail 0.0002 438 19460 4442 Gail 0.0002 401 18950 4725 Fail 0.0002 375 18628 4967 Fail 0.0002 346 18311 5292 Fail 0.0002 326 17922 5497 Fail 0.0002 308 17578 5707 Fail 0.0002 291 17261 5931 Fail 0.0002 274 16943 6183 Fail 0.0002 251 16612 6618 Fail 0.0002 227 16286 7174 Fail 0.0002 200 15964 7982 Fail 0. 0002 186 15665 8422 Fail 0.0002 174 15459 8884 Fail 0.0002 159 15137 9520 Fail 0.0002 152 14851 9770 Fail 0.0002 142 14587 10272 Fail 0.0003 134 14279 10655 Fail 0.0003 130 14086 10835 Fail 0.0003 123 13827 11241 Fail 0.0003 117 13568 11596 Fail 0.0003 113 13313 11781 Fail 0.0003 105 13045 12423 Fail 0.0003 101 12839 12711 Fail 0.0003 95 12567 13228 Fail 0.0003 91 12303 13519 Fail 0.0003 89 12097 13592 Fail 0.0003 87 11891 13667 Fail 0.0003 86 11637 13531 Fail 0.0003 82 11440 13951 Fail 0.0003 80 11185 13981 Fail 0.0003 75 10979 14638 Fail 0.0003 74 10760 14540 Fail 0.0003 72 10582 14697 Fail 0.0003 71 10443 14708 Fail 0.0003 67 10264 15319 Fail 0.0003 64 10099 15779 Fail 0.0003 60 9911 16518 Fail 0.0004 60 9714 16189 Fail 0.0004 58 9536 16441 Fail 0.0004 57 9343 16391 Fail 0.0004 55 9160 16654 Fail 0.0004 53 8959 16903 Fail 0.0004 51 8820 17294 Fail 0.0004 50 8717 17434 Fail 0.0004 49 8606 17563 Fail 0.0004 47 8485 18053 Fail 0.0004 46 8369 18193 Fail 0.0004 43 8235 19151 Fail 0.0004 43 8145 18941 Fail 0.0004 41 8029 19582 Fail 0.0004 39 7926 20323 Fail 0.0004 39 7810 20025 Fail 0.0004 38 7676 20200 Fail 0.0004 38 7586 19963 Fail 0.0004 38 7501 19739 Fail 0.0004 37 7421 20056 Fail 0.0004 37 7336 19827 Fail 0.0004 37 7238 19562 Fail 0.0005 36 7162 19894 Fail 0.0005 36 7050 19583 Fail 0.0005 35 6956 19874 Fail 0.0005 35 6853 19580 Fail 0.0005 34 6759 19879 Fail 0.0005 33 6670 20212 Fail 0.0005 33 6607 20021 F'ai.l 0.0005 32 6522 20381 Fail 0.0005 32 6429 20090 Fail 0 . 0005 31 6339 20448 Fail. 0 . 0005 31 6236 20116 Fail 0 . 0005 31 6178 19929 Fail 0 . 0005 30 6098 20326 Fail 0 . 0005 30 6022 20073 Fail 0 . 0005 27 5946 22022 Fail 0 . 0005 27 5883 21788 Fail 0 . 0005 26 5816 22369 Fail The development has an increase in flow durations from 1/2 predeveloped 2 year flow to the 2 year flow or more than a 10% increase from the 2 year to the 50 year flow. Water Quality BMP Flow and Volume for PLC 1 . On-line facility volume: 0 acre-feet On-line facility target flow: 0 eft. Adjusted for 15 min: 0 cfs. Off-line facility target flow: 0 cfs. Adjusted for 15 min: 0 cfs. J erind and Empind Changes No changes have been made. This program and accompanying documentation is provided 'as-is' without warranty of any kind. The entire risk regarding the performance and results of this program is assumed by the user. Clear Creek Solutions and the Washington State Department of Ecology disclaims all warranties, either expressed or implied, including but not limited to implied warranties of program and accompanying documentation. In no event shall Clear Creek Solutions and/or the Washington State Department of Ecology be liable for any damages whatsoever (including without limitation to damages for loss of business profits, loss of business information, business interruption, and the like) arising out of the use of, or inability to use this program even if Clear Creek Solutions or the Washington State Department of Ecology has been advised of the possibility of such damages.