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Storm Drainage Report 001~ Q~~~~~~ENGINEERING, INCORPORATED Storm Drainage Report Resubmittal #1 Rainier View Parcel No. 21724420501 9910 Durant St. Yelm, Washington Prepared for: Crest Builders 5516 75`" St. W. Lakewood. WA 98499 June 19, 2007 BASELINE Job No. 04-159 Prepared by: Dean H. Zavack, E.I.T. and Paul Adgar, E.I.T. Reviewed by: A. William V. Robinson, P.E. Gj ~/7/ 6/z2~ "I hereby state that this Storm Drainage Plan for Rainier View has been prepared by me or under my supervision end meets the standard of rare and expertise which is usual and customary in this oommunity for professional engineers. I understand that City of Yelm does not and will not assume liability for the suffciency, suitability, or performance of drainage facilities prepared by me." Land planning & Use • Engineering • Surveying 1910-64'" Avcnuc West • Tacoma, W A 98466 • (253) 565-4491 • pAX (253) 565-8563 • Seaule (20~ 8241205 "Our goal is to exceed your expectations" V ~, exa~rees a zoae ~ TABLE OF CONTENTS SECTION 1 -PROJECT DESCRIPTION 3 SECTION 2 -EXISTING CONDITIONS 3 SECTION 3 -INFILTRATION RATES AND SOILS REPORTS 3 SECTION 4 -WELLS AND SEPTIC SYSTEMS 4 SECTION 5 -FUEL TANKS 4 SECTION 6 -SUB-BASIN DESCRIPTION 4 SECTION 7 - ANALY SIS OF THE 100•YEAR FLOOD 4 SECTION 8 -AESTHETIC CONSIDERATIONS FOR FACILITIES 4 SECTION 9 -FACILITY SIZING AND DOWNSTREAM ANALYSIS 4 Water Quality 5 Flow Control 6 Conveyance 7 SECTION 10 -OTHER PERMITS OR CONDITIONS PLACED ON THIS PROJECT 8 APPENDICES Appendix A- Vicinity Map, Site Map, and Excerpts of Soil Analysis For Vista Green and Tahoma Terra Appendix B -Drainage Calculations and Basin Map Appendix C -Thurston County Flood Map 2of11 SECTION 1 -PROJECT DESCRIPTION The project proposal is to subdivide one 5.3 +l- acre parcel into 22 lots for future single- family residences. There was a residential single-family home on-site, which was recently destroyed by fire. The structure has since been removed. A public street extending from an adjoining subdivision with aturn-around knuckle is proposed as access to all 22 lots. The site is zoned Low Density Residential R-4. The 5.3-acre parcel located at 9910 Durant SL SE in Yelm, WA. The subject property is located in the SE quarter of Section 24, Township 17 North, Range 1 East, and W.M. See the site map in Appendix A. The project improvements consist of subdividing the parcel into 22 lots for single-family residences, a storm tract area, and 56-foot right of way dedication for the public road improvements and access to the residences. All interior streets shall be improved to Yelm City Standards for a Local Access Residential, including a 35-foot paved roadway with two 7-foot parking lanes. Rolled curb and gutter, and a 5-foot concrete sidewalk on one side. The new public road will be extended through an adjacent development called Vista Green and will dead end at the northerly end of site where an adjacent development (Wyndstone) will presumable make a connection to SW Berry Valley Road. SECTION 2 -EXISTING CONDITIONS The site currently is a vacant feld with a few trees and under story brush. The site slopes from northeast to southwest at slopes from 1% to 8%. Vista Green borders the site to the east and Tahoma Terra is across Durant St. to the west. Table 1 - Predevelooed Conditions Basin Pervious Impervious 2-year, 10-year, 100-year Descri lion Acres acres Peak rate Peak rate Peak rate Low growing 5.25 0 0.13 cfs 0.69 cfs ~ 1.53 cfs brush and grasslands SECTION 3 -INFILTRATION RATES AND SOILS REPORTS Based on Soil Conservation Service (SCS) of Thurston County the soils have been identified as 110 Spanaway Gravelly, Sandy, Loam which is a Hydrological Soil Group A. On June 14, 2007, Baseline Engineering sent representatives to verify the soil characteristics within the storm drainage tract. A. William V. Robinson, P.E., analyzed the soil at depths approximately 10' below the existing grade at the location of the infiltration pond. A. William V. Robinson, P.E., confirms that the soils are Spanaway Gravel with infiltration rates greater than 20 inlhr (3 min/in) and no indication of a water table 3-feet below the proposed infiltration facility, see soil logs in Appendix A. Two different geotechnical reports on adjacent sites confirm this soil classification. An excerpt from the geotechnical analysis from Parnell Engineering from the adjacent 3 of 11 development Vista Green and the adjacent development Tahoma Terra is included in Appendix A. SECTION 4 -WELLS AND SEPTIC SYSTEMS There is an existing well on-site that will be abandoned in accordance with the Department of Ecology (DOE) standards. SECTION 5 -FUEL TANKS There are no known fuel tanks located on the site. SECTION 6 -SUB-BASIN DESCRIPTION The 22-lot subdivision will have a conveyance, water treatment, and infiltration system for the public roadway and driveways. The water treatment and retention facilities will be situated in the dedicated storm tract of the site. The individual homes will each have a roof downspout infiltration system on its respective lot. It is to our understanding with the developer, Crest Builders, the homes will have a roof area of 2600 sf per lot. All stormwater will be retained on-site and disposed of through infiltration. SECTION 7 -ANALYSIS OF THE 100-YEAR FLOOD The project site is not located within the 100-year flood plain. See Appendix C for the FEMA Firm Map. SECTION 8 -AESTHETIC CONSIDERATIONS FOR FACILITIES Facilities will be located at the far end of the dedicated storm tract and will not detract from site aesthetics. SECTION 9 -FACILITY SIZING AND DOWNSTREAM ANALYSIS For the proposed 22-lot subdivision water quality, as well as stream bank erosion control (SBEC), will be designed and constructed for long-term disposal of the stormwater runoff. Waterworks 6.1.3.5 and the SBUH method were used to size the water quality and infiltration facilities in accordance to the 1992 DOE stormwater Design Manual. See Appendix B for calculations. The site is graded to flow stormwater toward the road and into catch basins that will convey the stormwater to the water treatment and quantity facilities located on Tract A of the site. See Site Map in Appendix A. Each lot will also contain an individual roof downspout infiltration trench that is designed for 2600 sf of roof area and will retain the 100-year 24-hour storm event. 4 ofll Facility 1 contains a permanent pool wet pond water treatment facility. Facility 1 treats stormwater from the pollution generating surtaces of the driveways and public street. See Appendix B for site description and drainage calculations. Waterworks 6.1.3.5 and the SBUH method were used to size the water quality and infiltration facilities. See Appendix B for site description and drainage calculations. The wet pond is designed to treat and contain stormwater flows up to the 6-month 24-hour storm. The 6-month 24-hour storm is defined by 1992 DOE stormwater Manual as 64% of the 2-year 24-hour storm. stormwater flows greater than the 6-month 24-hour storm will enter an overflow and flow directly into the overflow infiltration pond. The infiltration pond is designed to contain the 100-year 24-hour storm. By inspection the peak flow rates of the 100-year, 7-day storm are lower than the peak flows generated by the 100- year, 24-hour storm, therefore the 100-year, 24-hour storm will govern the design of the overflow infiltration pond. Flows greater than the 100-year 24-hour storm will enter an emergency overflow designed to drain into the drainage course along Durant Street, which will become a paved pedestrian walkway. Rainier View Developed Site Flows Storm ID (24-hour) Impervious Area' acres Pervious Area acres SBUH Calculated Flows 6-month 1.24 2.77 0.33 cfs 2- ear 1.24 2.77 0.63 cfs 10- ear 1.24 2.77 1.20 cfs 100-year 1.24 2.77 1.85 cfs 'Roof area not included since roofs stormwater flows into individual roof downspouts. Water Quality Facility 7 -Wet Pond: Water treatment for Rainier View will be provided by a permanent pool, two-cell wet pond to remove sediments (TSS) and free oil (TPH) from stormwater runoff before entering an overflow infiltration pond. The pond will have a geotextile liner to prevent infiltration into the Spanaway Gravel native soils, which have a high infiltration rate. The pond will be built to minimum 1992 DOE Standards and shall incorporate two cells. The wet pond cells are separated by a berm with 4 to 1 slopes that is submerged 1' below the design water surface elevation of 341.0. The total wet pond volume is designed to contain the 6-month 24-hour storm as was discussed with James E. Gibson, City of Yelm Development Services Engineer, on 1/22 to comply with 1992 DOE design standards. stormwater flows above the design water surface elevation of 341.0 will flow through a 12-inch spillway pipe directly into the overflow infiltration pond. This pipe will help prevent floatables from entering the infiltration pond, which is consistent with typical spillway berms of this design. The overflow infiltration pond was sized by Waterworks 6.1.3.5 to contain the 100-year 24-hour storm event. The first cell of the permanent pool wet pond is designed with one 4 to 1 side slopes and 3 to 1 side slopes to provide maintenance access. Cell 1 of the wet pond is designed with one-foot of sediment storage, 4-feet of active storage, and 1-foot of emergency freeboard. Cell 2 has 5-feet S of II of active storage and two 4 to 1 slopes to allow maintenance access between all three pond cells. Facility 1: Pretreatment Permanent Pool Wet Pond Design Storm SBUH Calculated SBUH Calculated Actual Wet Depth of ID Flow Volume Pond Active Wet Pond Volume before @ overflow overtlow' 6-month 24- 0.33 cfs 6246 cf 14,507 cf 5 feet Hour *Not including bottom 1-foot of cell 1 of pond intended for sediment storage. Flows generated from roofs will enter individual roof downspout infiltration trenches and will not require water quality because of the non-pollution generating surfaces of the roofs. Flow Control Facility 2 -Infiltration Pond The runoff from driveways, landscaping, and the public roadway will be collected with catch basins and conveyed through CPEP pipe materials to a two cell wet pond treatment facility and then into an overtlow infiltration pond. The water quality permanent pool two-cell wet pond is sized to contain the volume of the 6-month 24-hour storm. The 6-month 24-hour storm by 1992 DOE Stormwater Management Manual for Puget Sound is defined as 64% of the 2-year 24-hour storm. Storms exceeding the 6- month, 24-hour flow rate will enter the overflow infiltration pond through a with a 12-inch pipe that runs through the spillway berm linking the wet pond with the infiltration pond. The infiltration pond contains 1-foot of freeboard above the 100-year 24-hour storm water level for stability. The infiltration pond contains 29% additional volume capacity for emergency overflow volume. Storms greater than the 100-year 24-hour storm will enter the infiltration pond emergency overtlow which is set a[ % foot below maximum free board height and enter the drainage course along Durant St. SE. The infiltration pond has a draw down time of less than 48 hours as per 1992 DOE standards see Appendix B for calculations. 6 ofll Facility 2: Overflow Infiltration Pond (Calculated Dimensions are 62' by 21.67'- bottom dimensions with 3 to 1 slo es. Active Storac a De th = 3-feet Design Infiltration SBUH SBUH Design Actual Emergency Storm ID Rate Calculated Calculated Infiltration Pond Overflow Developed Active Rate Volume Volume 100-year Volume Capacity Flows before overflow 100- 20 in / hr 1.85 cfs 5493 cf' 20 inches / 7100 cf 29% year 24- hour Hour _~ "1-foot of freeboard not included in this volume calculation. Wet Pond volume not included in this volume calculation. The infiltration rate used for the preliminary sizing of the overflow infiltration pond is assumed 3 min per inch or 20 inches per hour based from Geotechnical Reports on 8124/05 by Parnell Engineering from the adjacent site Vista Green. An excerpt from this report in Appendix A. This infiltration rate was cross-referenced by examining the Geotechnical Report from Tahoma Terra, another adjacent site across Durant Street. This report, also from Parnell Engineering, was dated 1/19105 and an excerpt of this report is included in Appendix A. The Thurston County SCS also verifies this soil classification, see Appendix A. This infiltration rate of 3 min per inch infiltration rate will be verified for Rainier View with a soil analysis by A. William V. Robinson, P.E. from Baseline Engineering at the time of construction of the infiltration pond. Roof Downspout Infiltration Trenches: Flow generated from roofs will enter individual root downspout infiltration trenches and not enter the water quality infiltration pond because the non-pollution generating surfaces of the roofs will not require treatment. Each lot will contain an individual roof down spout infiltration trench sized for 2,600 sf of roof area. The individual roof downspout infiltration trenches will be sized for the 100-year 24-hour storm. Individual Roof Downsoout Infiltration Trench Summary 12600 sf Roof Area) Design Infiltration SBUH SBUH Actual Actual Storm ID Rate Calculated Calculated Trench Size Active 100-year Active Volume Volume' Flows 100-year 24- 20 in / hr .058 cfs 50.8 cf 3' by 19' by 51.3 cf Hour 3' dee 'Trench contains washed rock with 30% Voids. Volume contained in voids in rocks. Conveyance The conveyance designed is based on the 100-year 24-hour storm using flows calculated from the Santa Barbara Unit Hyd rograph Method (SBUH) and Waterworks 6.1.3.5 as shown in Calculations in Appendix B. 7ofll The runoff from the roadway and driveways will be collected using concrete rolled curb and gutter, catch basins, and CPEP or PVC pipe materials. Storm drainage from the public roadways will be conveyed [o the water qualitylinfiltration pond to remove total suspended solids (TSS) and free oil (TPH) from the stormwater before entering the overflow infiltration pond. Trapped oil contaminates and sediments can then be removed from the bottom of wet pond cell 1 at regular service intervals. Downstream Analysis All stormwater is to be retained on-site for stormwater flows up to the 100-year 24-hour storm. A downstream analysis was deemed unnecessary since all stormwater is to be retained on-site. SECTION 10 -OTHER PERMITS OR CONDITIONS PLACED ON THIS PROJECT An NPDES permit and site development permit will be required. No other permits are anticipated for this project as it is not affecting any existing wetlands and does not discharge into a surface water body. A 10-foot setback from all property lines and easement are required for stormwater facilities. Sewer will be provided by the City of Yelm through a S.T.E.P. system and will not interfere with Storm Drainage Facilities. SofLl APPENDIX A- VICINITY MAP, SITE PLAN 8 EXCERPTS OF SOIL ANALYSIS FROM VISTA GREEN AND TAHOMA TERRA e.. \ C ~~£~~ g ,I . u ry i ~ i I _ ~ ~ J l q o b$ 1A sa j I I h ~® h I ' ... i l V v g' 4 b d_ I I _ ~~ , h R°+ i I^ i 3Zd W ° ~ a ~ ~ i T e , a 3lN ~ , aossi- i5 i i ~ o d I a'' *~3 ` ~ n Im ,m _ ID w s , 6 i ~ f mwim •px r E a ~^ 1 I I Z p' ~ 1 I I i ^ ~ U vs _p' _L _ _ ~ I~ IIt~~~]yy(}~/ -~-F J4~/-- ~ I I I i I ~ I Y ~ rvnu m ~ I N F ____ _____ ___ ________ ~ ,_y ~I __ ____ __ i ` IiL ~ ~ ~ ~ ~ ~ I ~ ~ I im Ws ~ ~ I 4 I _ -' ~ I I I s I I I 9 ' p I ' I s ~ i _ I ~,,~ I g qa ~-'- ii 0 ' °a ,I~ OOSbI- _____ __ ________L___________~_______~ I ___a______. ___ _ .. I I __ __ ~ _ - II ~ 1 I yy~ I~O^ I Y \ ~, I ° ~ \l^ wp i ~ I ~ ~ Q I~ I Q I .^a ~ m Z~~~ eu _~~ h I I ~ m I I i ~ 4 n € I I I~ ~ I ~~ ~ ~ I I I I I I ______ _~ _ _ i ~ 1 ~. -.T! I I _1 _1 ______L ___ ~ _` ~ ~ ____ ~ I ~ ~ ~ ~ ~ ~ , ~ a,. ~,g,, j.,P /s ;., L{~.- ~ ~,. i h ~ a d OOSft- ~f~M 2" ~; i ... ~~ ~R S r i I I ,' .. . l ~ ; ~ i ~ ~. ~ , m 4~= ~ ~ i _ ~ ~~ ~ t ~ • ~; I t ,, ~ ~. ;~, ~ ;,r ;, ,,.~ e. I ~, ~ ~ ~ ~ ~ F~ ~ - ~ ~ ~ T° r ---- --- -~-' -- ~ . ~-- ~ t ~ I :. i . ~ I Sf ~ ~ BI ~ ~ k I I ~ ye I I ~ ~ ~ ' I ~` J m Y .x _ i i umvmq 1 I ~ YI -... 4~~ 'a'n nunl ~~-' d t~T___________I _________OOSZIQ n D ° ~L~~LN~ ENGINEERING, INCORPORATED ~tuul GlJeuel~neizt ~>~.r~riorzaGrfrurce~ June 15, 2007 Soil Log information for Rainier View Estates Site Address: 9910 Durant Street S.E. Yelm, WA 98597 BASELINE Engineering Job No. 04-159 Soil Loa #1 Located in the Southwest corner of site 20' East of fence 27' North of fence 0' - 2' Black loamy gravely sand with humus 2' - 10' Brawn medium sandy gravel with up to 8" cobles and a 2" pea gravel lens at T and roots to 10' 10' - 11 %' Coarse gravely sand No Groundwater Soil Loa #2 Located in the Southwest corner of site 25' North of fence & 120' East of fence 0' - 2' Black loamy gravely sand with humus 2' - 10 % ' Brown sandy gravel with three - 2" pea gravel lens 10 % ' - 11 %' Dark brown coarse sandy gravel - No Groundwater Recommended Design Infiltration Rate: 2 minutes per inch v~. Land Planning 8 Use Engineering Surveying 1910-64th Avenue West • Tacoma, WA 98466 (253) 565-4491 Fax (253) 565-8563 Seaflle (206) 624-1205 "The industry starts here" EXPIRES 6-2T-O6 Soi~ s ~ a~ 89 . NASHINGTON - SHEET NUMBER 24 ~- !l0-SPA,df~uRY C~RA~tC7 SA~~07Le _aton County. Washington ~) pNp CHIHICAL ppOPERTIES OF '111£ SOILS--Continued ~.. pBYSICAL ros on ~ i~ TABLE 15.-- factors 'Organ lc Soil ~ Shrink-swell ~iT~ matter permeabil Sty Availabcit lreaction~ potential ~ E T i ~~De th'~ Clay ~'~ water cap Y pct ~ i i i S maP symholnd P ~ '' i ' ' ' i ~ ~ i -i ern __ 5 5-15 ~ i i n ' ct % i 0.12-0.14 '15.6-6.0 {LOw_______ ____'i 0.1]{ ' i i 2-0-6.0 ', 0.14-0.17 .5.6-6.0 iiLOw____________'i 0.10, ~ 0-22 7 15 { 2 0 6.0 _ _ 5 6-6 0 Low ' '9------- ,22-26 `'-15 ; 2 0 6.0 0.05 0 OB 5.6-6 0 Low -- 0 O5. ~ _ 5 ~Ipana 26-38 5 15 ~ .._ 2 5_1 60 20 _ _ -- 015 ' 2-5 " { -- 5.1-6 0 Low -" ' --~ 0.11-0 13 5 1-6 5 Low -" _._.-__-.- -~- ~ 2 0-6.0 0.09-0 12 ___ 0 02 ' 10, 111- ---"-i 0-15' -- i 2 0-6.0 6 I-] 3 Low _-._... - ~. ', --- ~ 5-15 15 20. ~ )20 0.03-0 0 2 --' 0 151 SpanawaY 20_60' 0_g ~ -"_ " 0.11-0.13 -- 5.1-6.0 Low - -- ~0.10i _ __.. _ i i i . - i---~-"~"_- - ~-' 2.0-6.0 i 0.09-0.12 'i 5.1-6.5 'iLOw____________i0.02' ~---_ 'i 0_161 ___ ~I 2.0-6.0 ~~ 0.03-0.05 16.1-7.3 iLOw_____ 112, 113----'-"-- i i ~ Spanaway ,16-22. -' )20 i 122-601 0_5 _- ',0.15% 2 5-15 i ' ~ i , 0-11-0-13 'i 5.1-6.0 ~LOw--^-'"' 0 10' ~ ____ 119: ~~ i 'i 2.0-6.0 ~~ p-09-0.12 ,5.1-6.5 1LOx________ ___'~p.02 0-15 -__ i 2.0-6.0 i 0.03-0.05 '6.1-].3 iLOw------'"- SpanawaY-'------ ~' ' 115-20% >20 ---,0.20', 5 3-10 ,20-60. 0'S 1i 5.6-6.5 ',Low---^"- __10.281 ~ ii i i 2.0-6.0 0-09-0.12 - ~ ~ i 0-5 0.08-0.12 15.6-6.5 1LOw--'-'"-"-___i0.24~ ' i 2.0-6.0 i 'i6-1-73 iLOw_________ I ' ~ 0-5 i ~ NisquallY"-"----~ 5_31, 0-5 0-09-0-07 5-10 0-5 )20 ________J~037'i 5 i ' ~ 1 L i ~ 31-60% ' 'i ' 0.18-0.20 ',6.1-7.3 ow___ 032. ' 0.6-2.0 i 0.18-0.20 %6.1-].3 {Moderate-----"'~ ~ 1 _- ' 0-7 i 15-20 ~ 0.6-2.0 i ~ 5 0-20 115--'-"------ 'i 7_601 20-30 i ' 0.25-0.35 ',3.6-5-5 1Low-^--_ --___i0.32'1~ Sultan ' i 'i ~ 5-18 ' 0-6-2.0 i 0.20-0.30 '13.6-5.5 1LOw----' _ii0-321 i 0-7 i ' 0-2-0.6 ~ ,3.6-5.0 %MOderate------ ~ ~ 116______________~ ~ 5_18 03-0.6 ' ]-501 0.19-0.21 _1i p-20'1 2 5-10 Tacoma 150-601 20-50 -------_ p.12-0.14 ',5-1-6.0 iLOw--- ___ _10.201 ~ i i i ~ i i ~ 10-15 0-6-2.0 0.12-0.14 15.1-6.0 iLOw__ _________ ____i ' 0_11'1 ' ' ~ ___ ____ 117, 118, 119 ____i, 11-361 30-15 0.6_2.0 ___ _- -_'i 0.021 Ten lno ___ 0.06-0-0] i5-1-6.0 ',Low------ ~ i ~ 136-401 2 10 >20 ___ ____-'i 0.28'1 5 3-10 140-60', '5.6-].3 I'iLOw___ _IO-28'1 ~ ~ __ ' ~' 0.25-0.35 - 'i ' ' 0.6-2.0 i 0.25-0.35 'i 5.6-].3 ii LOw____________10-001 ' 0-111 "-- i 0.2-0.6 '~ 0.30-0.40 15.6-]•3 ~LOw----- ' ~ 120_____________ ~ ~ ~ Tisch '111-50'1 -_- 0.6-2.0 __ ____--10.291 3 5-10 i ii 150-601 '5.1-6.0 I'iLOw-- _0.24{ _______ i ~ ~ 0-25-035 'i i ~i p.6-2.0 0.25-0-35 15.1-6.0 1LOw--_---_---__10-15'1 ', 0-10 i~ ___ ; 0-6-2.0 ~' 0 20-0-30 X5.1-6.0 'Low-- ___ 121, 122_________110-15, ___ 0.6_2-0 i ___ __ ____________ _ ~ ' Vallton ilg _48I ""- ___ "-- 5 5-10 '~ 48 ___ ____10.32'. i ' ' ~ ~ i 'i 0.1]-0-20 15.1-6.0 iLOw________ i i ' 1 0.6-2.0 , 0.12-0.1] 15.1-6.0 MMOderate----_-_ 0' 20'1 '0 0-111 '--- ' - 123, 124--^"-- -~'1 25-35 ~ 0.6-2.0 'i 5.1-6.0 (Moderate ~ 11-4]'1 0.15-0.20 Wilkeson '4]_601 18-35 125. -- 10.32''1 5 3-9 ', 5.6-6.5 '~LOw_________ -10321 i i i %eror thenie I 2.0-6.0 0.25-035 --__ i i ~ 0-6 1'~ ___ 0.15-0.25 15.6-6.5 1LOx_______ _ _'i0-101 126, 12], 128----% 8_46' _ _ 1 2-0-6.0 ii 0.04-0-09 '15-6-6.5 ~GOw-----" 1 ~ 1 Yelm '46-60'11 0-5 6.0-20 1 ~ ' 1 osition and behavior characteristics of the map unit. + See description of the map unit foi comp LUBBESMEYER LONGMIRE PLAT Soils Report For Drainage Purposes Site Address: 15132 Longmire Street Yelm, Wa. 98597 Tax Parcel Number: 21724420800 Prepared For: Olympic Engineering 1252 Devon Loop NE Olympia, WA 98506 (360)870-2561 Contact: Chris Memtt, P.E. Prepared By: Parnell Engineering 10623 Hunters Lane S.E. Olympia, WA 98513 (360) 491-3243 Fax (360) 49]-3243 Contact: William Parnell, P.E. PE PARNELL ENGINEERING ~~5-~~ ~t~~~ SOIL EVALUATION REPORT FORM 7: GENERAL SITE INFORMATION PROJECT TITLE Lubbesmeyer Longmire Plat SHEET: 1 OF 1 PROJECT NO. OS134 DATE: BY24/O6 PREPARED BY :William Parnell, P.E. 1. SITE ADDRESS: 15132 Longmire Street Yelm, Wa. 98597 TAX PARCEL NUMBER: 21724420800 2. PROJECT DESCRIPTION: Create a 201ot residential subdivision. 3. SITE DESCRIPTION: The 4.7 acre project site is currently occupied by a single residential tlwelling antl two cutbuiltlings. Site relief is nearly level. The southern 180' of this parcel slopes to the south at a 1%slope. The remaining projeM site slopes to the north at a 1-2 % slope. Elevations range from a high of 353 ft. to a low of 346 R. at the northeast property corner. There are no site tlistinguishing features other than an existing domestic well. Site vegetation consists of uncropped feld grasses on the majority of the site, with maintained grass lawn antl landscaping atljacent to [he existing house. The project site is bounded by residential property to the north, east antl west, and by Longmire Street SE to the south. On-site soils are swell-drained Spanaway series formed in glacial oulwash. 4. SUMMARY OF SOILS WORK PERFORMED'. Two test pits were excavated by backhoe to a depth of 152' below the existing gratle. Soils were inspectetl by entering and visually logging each test pit to a depth of four feet. Soils beyond four feet were inspected by examining backhoe tailings. One double ring infiltration test was completed in test pit #1 at 96" below the existing grade. Test pit soil log tlata sheets and a double ring infltration test result are included in this report. 5. ADDITIONAL SOILS WORK RECOMMENDED'. Additional soils work should not be necessary unless drainage infltration facilities are locatetl outside the general area encompassed by the soil test pits. 6. FINDINGS: The Natural Resource Conservation Service soil survey for Thurston County mapped the on- sita soils ass Spanaway Gravelly Sandy Loam(110). Thelwotest pits confirmed the Spanaway tlesignation generally profiling a gravelly fine sandy loam surtace soil overlying an extremely gravelly 8 cobbley coarse- metliumsand substratum. The substratum gravels and sands were slightly loose. Winter water table was not present antl intlicators were not visible. A double ring infltration test completed at 96" below the existing grade revealed an infiltration rate of 46.5 in/hr. 7. RECOMMENDATIONS: The Spanaway soil series is a somewhat excessively drained soil that formetl in gravelly glacial outwash. Infiltration rates are generally rapid in the substratum soils. The specifed substratum C-horizon soils shoultl be targeted for all tlrainage infiltration facill[ies as noted in [he attached soil log data sheets. A design infiltration rate of 20 in/hr or less would be appropriate for these targetetl soils. During construction, care must be taken to prevent the erosion of exposetl soils. Drainage facility infiltration surfaces must be properly protectetl from contamination by the fne-grained upper horizon sails antl from compaction by construction site activities. Soils not properly pratecied will cause drainage infiltration facilities to prematurely fail. I hereby certify that I prepared this report, and conducted or supervised the peRormance of related work. I certify that I am qualified to do this work. I represent my work to be complete an accurate within the bounds of uncertainty inher/en~t to th~e~practice of `its science, antl to be suitable for its intended use. SIGNED: ~c//.C/GZ~,- , ` `-~~~~~ DATE: ~ (~~ ~~'S ' ~aVl D~ma ~ ~ roe SOIL EVALUATION REPORT FORM 1: GENERAL SITE INFORMATION PROJECT TITLE: Tahoma Terra SHEET: 1 OF 1 PROJECT NO.: 05100 DATE: 1/19/05 PREPARED BY: William Parnell. P.E. 1. SITE ADDRESS OR LEGAL DESCRIPTION: 14848 Longmire Street SE Yelm. WA 98597 TPN: 21724310100 2. PROJECT DESCRIPTION: Create a residential subdivision with all associated roadway. utility and landscaping improvements. 3. SITE DESCRIPTION: The project site is currently occupied by one residentlal building and several cuthuildings cenVally located on the parcel. Site relief is relatively flat with no distinguishing features. Vegetation consists of actively used agricultural pasture grasses. The project site is bounded by Berry Valley Road to Ne north. Longmire Street SE to the south, residential to the east and undeveloped property to the west. On-site sails are well drained and formed in glacial outwash. 4. SUMMARY OF SOILS WORK PERFORMED: Thirteen test pits were excavated by backhoe to a maximum depth of 180" helow existing grade. Soils were inspected by entering and visually logging each test pit to a depth of four feet. Soils beyond four fee[ were inspected by examining hackhoe tailings. Falling head percolation tests were completed in test pits #2, 5. 7, 9, 11 and 13 a[ a depth of 60" below the existing gratle. Test pit soil log data sheets and percolation test results are included in Mis report. 5. ADDITIONAL SOILS WORK RECOMMENDED: Additional soils work should not he necessary unless drainage infltration facilities are located outside the general area encompassed by the soil test pits. 6. FINDINGS: The National Resource Conservation Service of Thurston County mapped Ne on-site soils as a Spanaway Gravelly Sandy Loam (170). All test pits confrm this designation. All test pits generally revealed gravelly fne sandy loam surtace soils, overlying an extremely gravelly and cobbley coarse sand substratum. SubsVa[um sails were moderately loose with no fnes present. Winter water table was not present in any test pits. Falling head percolation tests were completed revealing the following infltration rates: Test pit #2 - 2160 in/hr, #5 - 144 in/hr, #7 - 188 in/hr, # 9 - 617 in/hr, #11 - 360 in/hr, #13 - fi8.5 in/hr. Tests were completed utilizing a 6" diameter PVC pipe to prevent sidewall collapse. 7. RECOMMENDATIONS: The Spanaway soil series is a somewhat excessively drained soil that formed in glacial outwash. Infltraticn rates are generally rapid in the substratum sails. The substratum soils should he targeted for all drainage infltration facilities. A design infltration rate of 20 in/hr or less would be appropriate for all targeted O-horizon soils as recommended in the attached soil log information sheets. During construction, care must be taken to prevent erosion of exposed soils. Drainage facility infiltration surtaces must he properly protected from contamination by the fne-grained upper horizon soils and from compaction by site construction activities. Soils not properly protected will cause drainage infiltration facilities to prematurely fail. I hereby certi(y that I prepared this report. and conducted or supervised the pedormance of related work. I certify that I am qualifed to do this work. 1 represent my work to he complete an accurate within the hounds of uncertainty inherent to-ih practice of soils science, and to be suitable for its intended use. ~ //~ j ~* v -.. t... SIGNED: L •.C "wx ~ ~~ y t ~^~ 4 DATE: y~4~OS ~ "' I`t'' r y_.> _ a:._. .Y i; - vA ,t +~; ,.c APPENDIX B -BASIN MAP AND DRAINAGE CALCULATIONS l0 of 11 -- -- ;- ~ ~ - I ~,~ -- _ ~e °~~ r ~, ~ ``q ~ tg;~ (~4 s l '•y~ r4- yA I~ ~. _ ~ 8 '. 9't~ •~4 4 1 4~ i 4~ Po 4g ~~` \ 4 \~ 4 ~ 4 Q 4 ~'e i Z s _ ~ M ynti ~ ~ m ~ ''r 6~ i W ~ _ ~ ~ ~ r4 4'~. W 9~ `f ~ ~4~ ~z ____ ~ o ``^ ~~ "4. ~ ~~a ~y ~. `°r e,~l ,~ ~~~~ ~ // ~~ ~_ F ky~ m s 4~4 U \a i r i ~.~ " w 4 ~~-- -, ~ ; ,~_ ~' ~_ ~ t ie~az ~av ,, .,, _-laa{lIRINVfI!!O -- ___ ~~t! ~~~, ,~ ~ ~~ ^ ~ ~ WaterWOrks HMS Report Fdtlay, February 16, 200] Paoe 1 Rainier View 04-159 Yelm, WA per 1992 DOE Stormwater Management Manual Standards Predeveloped Flows For Rainier View Project Precips [2 yr] 2.00 in [5 yr] 2.50 in [10 yr] 3.00 in [25 yr] 3.50 in [100 yr] 4.00 in [6 mo] 1.28 in Drainage Area: predeveloped Hyd Method: SBUH Hyd Peak Factor: 484.00 Storm Dur 24.00 hrs Area CN Pervious 5.2800 ac 74.00 Impervious 0.0000 ac 0.00 Total 5.2800 ac Supporting Data: Pervious CN Data: low growing brush & grasslands 74.00 Pervious TC Data: Flow type: Description: Loss Method: SCS CN Number SCS Abs: 0.20 TC 0.17 hrs 0.00 hrs 5.2800 ac Leng[h: Slope: Coeff: Travel Time 440.00 ft 2.00 % 5.0000 10.37 min 6 mo Flow Time Volume Summary: 0.0390 cfs 22.00 hrs 1560.14 cf - 0.0358 acft 2 yr Flow Time Volume Summary: 0.1300 cfs 9.00 hrs fi700.66 cf - 0.1538 acft 10 yr Flow Time Volume Summary: 0.6900 cfs 8.00 hrs 17406.63 cf - 0.3996 acft 25 yr Flow Time Volume Summary: 1.0916 cfs 8.00 hrs 23762.31 cf - 0.5455 acft 100 yr Flow Time Volume Summary: 1.5336 cfs 8.00 hrs 30592.76 cf - 0.7023 acft Baseline ~ ~ I ~ - ~ e ~ ~ I ~ 11 ~ k ~ \ A I F WO ~ y ~$ ~ / U ' ~ F ~ 8 ~\ ` t c m ~. 4 ~ ~w Q ~. n 2 P ~ ~ - ~ ' . ,,_ « ~m ~ ~ ~ ~. e . m„ t' ~ ~ ~ ~ ~ . ~ ~ Q / n" m - ~ ~ ~ W ____ ~ ~ m ~ 1 1 m p J ` ~ 1 M ~ g(} ~n r„ 1 Rn , ~ . ~ / ~~ / ~i ~ o 4 N ~ ~ w ~ ~ Y: _ -_~ p ;ice ~ s ~~ i W ~ I m - - ~g ~ y ~ I r ~ _ ~ « ~/~ ~ ( `Nw ~~~ Q ~ r ~~1~ 1 u '' s L gY{8n ON ~ ~ ~ ~ id i . u .. . i l ~~ _ ~ ~ _~ ~aaFIIS . . .. , __~__-__ __ ,. _ _- _ d ~j. WaterWOrks HMS Repoli Thurstlay, January 11.2007 Developed Flows for Rainier View 04-159 Yelm, WA per 1992 DOE Stormwater Management Manual Standards Project Precips [2 yr] 2.00 in [5 yr] 2.50 in [10 yr] 3.00 in [25 yr] 3.50 in [100 yr] 4.00 in [6 mo] 1.28 in (6-month = 64 % of 2-year for 1992 DOE) Drainage Area: Dev Hyd Method: SBUH Hyd Peak Factor: 484.00 Storm Dur 24.00 hrs Area CN Pervious 2.7700 ac 78.00 Impervious 1.2400 ac 98.00 Total 4.0100 ac Supporting Data: Pervious CN Da[a: Landscaping 78.00 Impervious CN Data: Road, driveways, pond area 98.00 shared driveway for lots 8, 11 98.00 Pervious TC Data: Flow type: Description: Sheet flow down landscaping Sheet flow down road Shallow flow down road Channel conveyance through N-12 pipe Impervious TC Data: Flow type: Description: Sheet flow dawn driveway Sheet flow down road to CB Loss Method: SCS CN Number SCS Abs: 0.20 TC 0.50 hrs 0.10 hrs 2.7700 ac 1.1400 ac 0.1000 ac Length: Slope: Coeff: Travel Time 225.00 ft 1.50% 0.1500 26.60 min 75.00 ft 1.00 % 0.0110 1.61 min 130.00 ft 1.00 % 27.0000 0.80 min 250.00 ft 1.00°/ 42.0000 0.99 min Length: Slope: Coeff: Travel Time 195.00 ff 2.00 % 0.0110 2.61 min 105.00 ft 1.00 % 0.0110 2.10 min Channel conve ante with N-12 i e mat. 250.00 ft 1.00 % 42.0000 0.99 min 6 mo Flow Time Volume Summary: 0.3316 cfs 8.00 hrs 6245.92 cf - 0.1434 acft 2 yr Flow Time Volume Summary: 0.6261 cfs 8.00 hrs 12856.27 d- 0.2951 acft 10 yr Flow Time Volume Summary: 1.2012 cfs 8.00 hrs 23809.96 cf - 0.5466 acft 100 yr Flow Time Volume Summary: 1.8526 cfs 8.00 hrs 35919.42 cf - 0.8246 acft Engineering Inc. WaterWOrks HMS Report Thursday, January 11, 2007 ProjecC 041591n(I Pantl2 p 1 Rainier View 04-159 (Calculated Infiltration Pond Size 28' by 41' with 3.00 h: 1v and 3-foot deep) Project Precips m~ 103 [2 yr] z.oo m 1' [5 yr] 2.50 in ~ ] [10 yr] 3.00 in 3~~.1V 100-year 24-hour 3 4rc<byrQ [25 yr] 3.50 in storm GL' [100 yr] 4.00 in _ c~ i~a [6 mo] 1.28 in ~ fig, ~ RLPCOMPUTE [Routing] SUMMARY 100 yr Match O: 0.00 cfs Peak Out O: 0.53 cfs -Peak Stg: 102.95 ft -Active Vol: 0.13 acft Summary Report of all RLPooI Data BASLI5T2 [Dev] Using [TYPEIA] As [100 yr] LSTEND BasinlD Peak O Peak T Peak Vol Area Method Raintype Event ------- (cfs) (hrs) (ac-ft) ac (Loss Dev 1.85 8.00 O.S246 4.01 SBUHISCS TVPEIA 100 yr BASLIST [rYPE1A] AS [100 yr] DETAILED [Dev] Drainage Area: Dev Hyd Method: SBUH Hyd Peak Factor: 484.00 Storm Dur 24.00 hrs Area CN Pervious 2.7700 ac 78.00 Impervious 1.2400 ac 98.00 Total 4.0100 ac Supporting Data: Pervious CN Da[a: Landscaping 78.00 Impervious CN Data: Road, driveways, pond area 98.00 shared driveway for lots 8, 11 98.00 Pervious TC Data: Flow type: Description: Sheet flow down landscaping Sheet flow down road Shallow flow down road Channel conveyance through N-12 pipe Impervious TC Data: Flow type: Description: Sheet flow down driveway Sheet flow down road to CB Loss Method: SCS CN Number SCS Abs: 0.20 TC 0.50 hrs 0.10 hrs 2.7700 ac 1.1400 ac 0.1000 ac Length: Slope: Cceft: Travel Time 225.00 ft 1.50 % 0.1500 26.60 min 75.00 ft 1.00 % 0.0110 1.61 min 130.00 ft 1.00 % 27.0000 0.80 min 250.00 fl 1.00 % 42.0000 0.99 min Length: Slope: Coeff: Travel Time 195.00 ft 2.00°/ 0.0110 2.61 min 105.00 ft 1.00% 0.0110 7.10 min Channel conveyance with N-12 pipe mat 250 00 ft 1 00 % 42 0000 0 99 min 100 yr Flow Time Volume Summary: 1.8526 cfs 8.00 hrs 35919.42 cf - 0.8246 acft Baseline WalerWOrks HMS Repotl Ttlursday, January 11, 2007 Project: 041591nfil Pontl2 p 2 HYDLIST SUMMARY [100yr out] LSTEND HydID PeakO PeakT Peak Vol Cont Area ------- (cfs) (hrs) (ac-ft) (ac) 100yr out 0.53 ].17 0.8251 4.0100 STORLIST pnfl Pond] LSTEND Node ID: Infil Pond Desc: Infiltration Pond Start EI: 100.0000 ft Maz EI: 103.0000 ft Contrib Basin: Contrib Hyd: Lenqth ss1 ss2 Width ss3 ss4 41.0000 ft 3.OOh:1v 3.OOh:1v 28.000Oft 3.OOh:1v 3.OOhav Bottom area only with infltration DISCHLIST [Infiltration] LSTEND Control Structure ID: Infiltration -Infiltration control structure Descrip: Multiple Orifce Start EI Max EI Increment 100.0000 ft 103.0000 ft 0.10 Infil: 20.00 in/hr Multiplier: 1.00 STORTABLE TABLE [Infl Pond] LSTEND Stage-Storge Table for node Infil Pond Stage Vol Vol (ft) (cf) (ac-ft) 1ap .po p.pp o.apop 1op _1a 116sa o.ooz7 100 .20 237.98 0.0055 100 .30 363.35 0.0083 100 .40 493.p9 0.0113 100 .50 62].25 0.0144 100 .fi0 765.91 0.0176 100 .70 909.15 0.0209 100 .80 1057.02 0.0243 100 .90 1209.62 0.02]6 101 .00 136].p0 p.0314 101 .10 1529.24 0.0351 101 .20 1696 a2 0.0389 101 .30 1868.59 p.p429 101. 40 2045.85 0.0470 101. 50 2228.25 0.0512 101. 60 2415.8] 0.0555 Slage Vol Vol (ft) (cf) (ac-ft) 101 .70 zsoe .7s o.osss mT fio zso7 .os a.osa4 101. 90 3010 .78 0.0691 102. 00 3220 .00 0.0]39 102. 10 3434 .80 0.0789 102. 20 3655 .26 0.0839 102. 30 3681 .43 0.0891 102. 40 4113 di 0.0944 102. 50 4351 .25 0.0999 102. fi0 4595 .03 0.1055 102. ]0 4844 .83 0.1112 102. 80 5100 .70 0.1171 102. 90 5362 ,74 0.1231 103 .00 5631 .00 0.1293 Engineering Inc. WaterWOrks HMS Repotl Mantlay, January 22, 2007 Project: 041591nf1 Pontl2 Pape 1 Wet Pond For Rainier View 04-159 Yelm, WA per 1992 DOE Stormwater Management Manual Standards Project Precips +o~ of p;pe ~bwergr~ [z yr] z.oo in = [5 yr] 2.50 in ~jhlly Cell1 ~}~ .q h;1V- Cell2 5~ Sn~~„ [10 yr] 3.00 in ~ "~ °" [25 yr] 3.50 in ~~ 1'~tiaxi ' °iW [100 yr] 4.00 in cJyr,~ [6 mo] 1.28 in (6-month = 64°/ of 2-year for 1992 DOE) Drainage Area: Dev Hyd Method: SBUH Hyd Peak Factor: 484.00 Storm Dur 24.00 hrs Area CN Pervious 2.7700 ac 78.00 Impervious 1.2400 ac 98.00 Total 4.0100 ac Supporting Data: Pervious CN Data: Landscaping 78.00 Impervious CN Da[a: Road, driveways, pond area 98.00 shared driveway for lots 8, 11 98.00 Pervious TC Data: Flow type: Description: Sheet flow down landscaping Sheet flow down road Shallow flow down road Channel conveyance through N-12 pipe Impervious TC Data: Flow type: Description: Sheet flow down tlriveway Sheet Flaw down road to CB Channel conveyance with N-12 pipe mat. 6 mo Flaw Time Summary: 0.3316 cfs 8.00 hrs Loss Method: SCS CN Number SCS Abs: 0.20 TC 0.50 hrs 0.10 hrs 2.7700 ac 1.1400 ac 0.1000 ac Length: Slope: Coeff: Travel Time 225.00 ff 1.50 % 0.1500 26.60 min 75.00 ft 1.00% 0.0110 1.61 min 130.00 f[ 1.00% 27.0000 0.80 min 250.00 ff 1.00 % 42.0000 0.99 min Length: Slope: Coeff: Travel Time 195.00 ft 2.00 % 0.0110 2.61 min 105.OOft 1.00% 0.0110 2.10 min 250.00 ft 1.00 % 42.0000 0.99 min Volume 6245.92 cf - 0.1434 acft 1992 DOE Requires Wet pond to Contain Volume of 6-month 24-Hour Storm Pond Volume should have minimum 6245.9 cf of volume using SBUH method for 6-month 24- hourstorm. Actual Pontl size will have a minimum volume of 14,507 cf which gives a Factor of Safety (FS) of 2.3. Baseline WalerWOrks HMS Repon Wednestlay, January 10, 200] Project OA1591nfl POntl2 P 1 Individual Roof Downspouts For 2600 sf Roof Area Trench size (3' by 19' by 3' Deep) Rainier View 04-159 Yelm, WA per 1992 DOE Stormwater Management Manual Standards Project Precips [2 yr] [5 yr] 2.00 in 2.50 in 30 % Voids in [10 yr] 3.00 in ~ [25 yr] 3.50 in 3 [100 yr] 4.00 in Washed Rack p ~ [6 ma] 1.28 in rerfw.-~ ~~ RLPCOMPUTE [roof routing] SUMMARY 3r 100 yr Match O: 0.00 cis Peak Out O: 0.03 cfs -Peak Stg: 102.97 ft -Active Vol: 50.77 cf Summary Report of all RLPooI Data BASLIST2 [Single Roof] Using [rYPEtA] As [100 yr] LSTEND BasinlD Peak O Peak T Peak Vol Area Melhod Raintype Event ------ (cfs) (hrs) (ac-ft) ac /Loss single ROOF 0.06 ].83 0.0188 0.06 SBUHISCS TVPEIA 100 yr BASLIST [TYPEIA] AS [100 yr] DETAILED [Single Roof) LSTEND Drainage Area: Single Roof Hyd Method: SBUH Hyd Loss Method: SCS CN Number Peak Factor: 484.00 SCS Abs: 0.20 Storm Dur 24.00 hrs Area CN TC Pervious 0.0000 ac 0.00 0.00 hrs Impervious 0.0600 ac 98.00 0.01 hrs Total 0.0600 ac Supporting Data: Impervious CN Data: 2500 sf per home 98.00 0.0600 ac Impervious TC Data: Flaw type: Description: Length: Slope: Coeff: Travel Time Sheet flow down roof 30.00 ft 3.00 % 0.0110 0.50 min Channel N-12 pipe conveyance to trench 40.00 ft 1.00 % 42.0000 0.16 min TC of 0.66 min < 5 min, program will use a tc o f 5 min in computations. 100 yr Flow Time Volume Summary: 0.0578 cfs 7.83 hrs 820.10 cf - 0.0188 acft Inc. Wa[erWOrks HMS Report Wetlnestlay, January 10, 200] Project: 041591nfil Pontl2 P 2 STORLIST [roof trench] LSTEND Node ID: roof trench Desc: Infl[ration Pond Start EI: 100.0000 R Max EI: 103.0000 ft Contrib Basin: Contrib H d: Length Wid[h Void Ratio 19.0000 ft 3.0000 ft 30.00 Bottom area only with infiltration DISCHLIST [Infltration] LSTEND Control Structure ID: Infiltration -Infiltration control structure Descrip: Multiple Orifice Stan EI Max EI Increment 100.0000 ft 103.0000 ft 0.10 Infil: 20.00 in/hr Multiplier: 1.00 STORTABLE TABLE [roof trench] LSTEND Stage-Storge Table far node roof trench Stage Vol Vol (ft) (cf) (ac-f[) 100.00 0.00 a.oooo 100.10 1.]1 6.6006 1 oo.zo a4z 0.0001 100.36 s.13 0.0001 100.40 6.84 p.0002 100.50 8.55 0.0002 100.60 10.2fi 0.0002 100.]0 11.9] 0.0003 100.80 13.68 0.0003 100.90 15.39 p.0004 101.00 n.10 0.0004 101.10 18.61 a.ooo4 1o1.zo zos2 o.ooos 101.30 zz z3 o.0oos m1 ao zasa o.ooos 1n1so 2sss o.oa0s 1o1s6 2].3s 0.0oos Stage Vol Vol (K) (cf) lac-ft) 101.]0 zs.m 0.060] 101.80 36.]e 0.000] m1.96 az a9 o.oao] 102.00 34.20 0.0008 102.10 35.91 00008 102.20 3].62 0.0009 102.30 39.33 0.0009 102.40 41.04 O.OOO9 102.50 a2]5 0.0010 l ozso 4a.4s 0.0010 1oz.]o as.n 0.6011 102.80 4].88 0.0011 l ozso a0s9 0.0011 103.00 s1.3o o.oalz Inc. MANNING'S EQUATION FOR OPEN CHANNEL FLOV~ 12" CIRCULAR PIPE CAPACITY i I Q- 1.49AR3Sz n Input Values d =diameter of pipe 1.00 h h =height of flow 0.90 ft S = longitutlinal slope 0.005 fVft n =roughness coefficien 0.014 Calculated Variables V =Velocity 3.36 fps A -Area P =Perimeter WA =Wetted Area 0.745 WP =Wetted Perimeter 2.498 ft = y rau is a ius ercent u g = uantity o ow c s Minimum pipe slope Check for Capacity: 100-year 24-hour Storm Flow = 1.86 cfs 2.50 c£s > 1.86 cfs Has Capacity Infiltration Pond 48-hour Drawdown Time Requirement Ta~awaow~ _ (Pond Volume) /[Bottom Area x hfiltration Rate x (1 ft/12 inches)] Ta~waow~ = 5493 cf / [962 sf x 20 inches / hour x Q ft/12 inches) ] Tarewaow„ = 3.42 hours STORMWATER MANAGEMENT MANUAL FOR THE PUGET SOUND BASIN APPENDIE AIII-1.1 IBOPLWIAL MAPS FOR D63ION STORKS Included in this appendix are the 2, 10 and 100-year, 24-pour design storm and mean annual precipitet ion ieopluvial maps for the Puget Sound basin. These have been taken from NOAA Atl ae 2 "Precipitation - Prequency Atlas of the Neetern United States, Volume IX, Washington. III-1-43 FBERUARY, 1992 ~, r~ ' ~ STORHWATER MANAGEMENT MANUAL FOR THE POGET SOUND BAEIN IZI-1-44 FEBRUARY, 1992 STORMWATEA MANAGEMENT MANUAL FOR THE PUGET SOUND BAE IN fie ilIV -Y5 edHRUARY, 1992 i :.iY/ STORHWATER RANAGEMENT RANUAL FOR THE PUGET SOUND BASIN 124 123 122 121 49r-__- ~s ~ eo , ~` is_~/ ~ -- w - ~~ 1 ~ o d ~ a L. GA 1 q fPIUAY M4~~ F URi $IPNI ~ ~E r ''~se4s v 1~ ~ 90~{ ~ I s ~ ~ ~ L1 S 3 ~yy ~yII~ ~~ is'- ~~~ ~\~7~~.~J,~ 15 fM1~A~ [~~CNmr_ll ,~ _ L~ 10 ~ \~~ WASHINGTON I '° ', to o la 20 ao qo ~~ MILES 10~~, i Figure 30 I f ISOPLUVIAlS F 100-YR 24~NR PRECIPITgTION ~. IN TENTHS OF N INCH ~, 124 123 n nu•'15 \~~ 0.TLg5 2. Volume I% M Oy LL5. Mwrtmenl of C I Oceemwntl 0.11me pgnlt R11n it WntM Eemu.OXKe of M' M for U.S Oeptlmenl ol0.L verveuon Snm~e. EnRmeerln~ 72i 71 ~~ STOAMWATER MANAGEMENT MANUAL FOA THE PUGET SOUND EASIN Table III-1.3 SCS Western Washington Runoff Curve Numbers (Published by 5C8 in 1982) Runoff curve numbers Eor ee lectetl agricultural, suburban and urban LAND UEE DESCRIPTION CURVE NUMBERS 8Y H OLOGIC SOIL GROUP A B C 0 Cultivated land(1 winter condition 86 91 94 95 Movnt aln open areas: low growing brush S grasslands ]4 82 89 92 Meadow or pasture: 65 7B 85 89 Nood or £areet land: undi eturbed 42 64 ]6 81 wood or forest land: young second growth or brush 55 72 E1 86 Orchard: with cover cro B1 88 92 94 Open spaces, lawns, parka, golf courses, cemeteries, landscaping. Good condition: grass cover on L75a of the 68 80 86 90 area Fair eondit ion: grass cover on 50-]58 of 77 85 90 92 the area Gravel roads 6 parki ng lots: 76 85 89 91 Dirt roads 6 erkin lots: ]2 82 87 89 Impervious surfaces, pav¢ment, roofs etc. ~ I 98 96 98 98 O n water bodies: lakes, wetlands, onds etc. ~00 ~ 100 100 100 Single family reeidential(2 ): Dwelling Unit /Gross Acre •Imperv iove(3) Separ ate curve number 1.0 DU/GA 15' shell be select ed for 1.5 DU/GA 20 pervi ous 6 impe rvious 2.0 DU/GA 25 porti ons of the Bite 2.5 DU/GA 30 or be e in 3.0 DU/GA 34 3.5 DU/GA 38 4.0 DU/GA 42 4.5 DU/GA 46 5.0 DU/GA 98 5.5 DU/GA 50 6.0 DU/GA 52 6.5 DU/GA 54 7.0 DU/GA 56 PUD'er condos, apart ment e, •impervioue commercial businesses 6 moat be industrial erase computed (1) For a more detailed description of agricultural land use curve numbers refer to National Engineering Handbook, Sec. 4, Hydrology, Chapter 9, August 1972. (2) Ae eumee roof and driveway runoff ie directed into street/storm ey stem. (3) The remaining pervious areas (lawn) are considered to be in good condition for these eurv¢ numbers. III-1-12 FEBRUARY, 1992 APPENDIX C - THURSTON COUNTY FLOOD MAP 11 of 11 Thurston County Map Output Page Page I of 1 Thurston ~<4 ~ F~ ~ e[gpv veuev no se sw eexavvweeer ~,~s;~ ~.o.~ ~ e ~ ~>°~ 5 ~~.FE ~ tE ~ m -w4 ROSE. o [seen >'¢clnimer TM1umon Counir n,nkes even effon,o ensue iM1Ui iM1ls mnV Is a mie and mm.ev~es nmtlon nnne,~a.n ofeonmr snvemm<in. enw.YCr, ~n<-e'o,mw non all LEGEND elm<d p<rsonnel make no wamnry, vxp¢sxN or Implied reganling,M1e accuracy, mpln oleo inform on JlselosW on iMS map. Noe tloee iM1e fnun,y a /~/ h]ajor Roads .Flood Zones sed br,ne, ofinls mnp_ pll filly brany I ~SCO njury ev „ne tulles mpcn szlnl<pu ,npPGcublc lmr, TM1m'slon County tlisdnims all Roads conies, <xprcss nr impncJ, mdnJln3, nw no, Ilmi,eJ m, Implied a anfms of iTeleham lCater Bodies bilny. dum Gm ss ~ru pnr cWOrpuryos andn imiingenonso(propri<inryrlynu. Streams I I I I J.I I 1 br. -I~II17 I C vne n Zooiug II I 'd` ~ I 1~ ~I- v I 1 ~ I IamnEvs,nu vs,l I m ' ~ ~~CORteID'S nal l_ ,x, r uulOC aLL-ale. COQ, Oi ~h< taetlands a - Cities ll,on:e., [12009 ~Tnuamn Coun,y GwDwa Cenral -~ (lr^It+,+ 2404Ileritoge Cnurt5W, 3rd Flaor ~~~°~°r t~'etlavd BUffea Ba[cek OI WA 980021031 ymp~a, http://geomap l .geodata.org/servlet/com.esri.esrimap.Esrimap?ServiceName=cadastralov&... 2/ 16/2007 in` r i Est ~e Mood a/U -~ " W m z J W Z Q Q Qoo Z O w °o t= LL M Z ~~ ~X ~ W Q O ~ W W a zz U 00 X w W i q 151Nbtly~~ " ~$} x ~ ~ e j~ ~ a ~ ~~ DQ ~`o ClyyM1~ O ¢U iO Y 8 ~G °~ n 2~ iw "- Q W Z O JN X W Z O N x ~,,~ o a o a LL LL . ~~ ~O ~m ~~- ~ s ~U