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Larson & Associates surveyors. engineers and planners 9027 Pacific Avenue, Suite 4 Tacoma. WA 98444 LUND SHORT PLAT II November 11, 2015 TECHNICAL INFORMATION REPORT PROPONENT: JKMONARCH CONT ACT: ROY SIMMONS P.O. BOX 188 PUYALLUP, WA98371 253-840-5660 PREPARED BY: Larson & Associates surveyors, engineers and planners 9027 Pacific Avenue, Suite 4 Tacoma, WA 98444 (253) 474-3404 iAfilI OJF OONlJENJS PROJECT ENGINEER'S CERTIFICATION .......................................................................................................... I T.I.R. SECTION I -PROJECT OVERVIEW .. EXISTINU Srr>: CONDITIONS SUMMARY PROPOSED DEVELOPED SITE CONDITIONS SUMMARY SECTION II -CONDITIONS AND REQUIREMENTS SUMMARY .. SECTION III -OffSITE ANALYSIS SECTION IV -STORMWATER FACILITY ANALYSIS & DESIGN . SECTION V -CONVEYANCE SYSTEM AND DESIUN , SECTION VI -SPc.l"IAI REPORTS AND STUDIES . SECTION VII -OTHER PERMITS . SECTION VIII -ESC ANALYSIS AND DESIGN . SFCTION IX -BOND QUANTITIES WORKSHEET .. SECTION X-OPERATIONS AND MAINTENANCE MANIJAL.. ... ' 2 ............ 2 ............. 3 . .......... 3 ............... 3 ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,.,,,,, ... 34 ..... ' ... 4 ''' ... ''''' 4 ,,,,,,,,,,,,,, ................................. 4 . ........................ .4 . ..................... 4 ................... 4 APPENDIX "A" .......................................................................................... MISCELLANEOUS INFORMATION VICINTlTY MAP PARCEL MAP. AERIAL MAP SCS SOILS INFORMATION. FLOOD INSURANCE RATE MAP .... FLOWCHART FOR DETERMIGING APPLICATION OF FLOW CONTROL BMPS .. GEOTECH REPORT. ........ A2 ..A3 .................. A4 . ....................... A5-A8 . ....... A9 .. ............... AIO ........................ AII-A16 APPENDIX ''B'' ...................................................................................... CONSTRUCTION SWPPP AND BMP'S APPENDIX "C" ..................................................................... OPERATION AND MAINTENCANCE MANUAL PROJECT ENGINEER'S CERTIFICATION I hereby state that this Technical Information Report for Lund Short Plat II has been prepared by me or under my supervision and meets the standard of care and expertise which is usual and customary in this community for professional engineers. I understand that the City of Renton does not and will not assume liability for the sufficiency, suitability, or performance of pollution prevention facilities prepared by me. TECHNICAL INFORMATION REPORT SECTION l -PROJECT OVERVIEW This TIR will focus its attention on providing information to obtain a clearing and grading and site development permit for the proposed Lund Short Plat II project. The project is located in the NEV, of the NEY,, of Section 29, Township 23 North. Range 5 East of the Willamette Meridian in King County, Washington. Lot I of the original Lund Short Plat is to be divided into two lots (Lots A & B) to make up the Lund Short Plat II project. The site consists of approximately 0.24 acres and is located on 16203 1141h Ave. SE on parcel #0088000177. The proposed driveway for Lot "A" (approximately 756 SF) will be constructed off of SE l 62"d St. and the proposed driveway for Lot "B" (approximately 651 SF) will be constructed off of 114 1h Ave SE. A portion of the roof runoff from Lot "A" (approximately 880 SF) and Lot "B" (approximately 100 SF) will be captured via a roof downspout tightline and conveyed to a yard drain. The runoff will then be directed to an existing 4" perforated stub-out connection and thereafter to a catch basin located in SE l 62"d St. towards the northwest end of the site. A "restricted footprint credit calculation" will be utilized to direct the remainder of roof runoff to the yards for dispersion via downspouts and splash blocks. The proposed driveway area for Lot "A" will be graded to drain to the east onto a 2' wide x 0.5' deep gravel transition strip that borders the east end of the driveway. The runoff will then flow over a IO' wide vegetated flow path for dispersion into the surrounding soils. The proposed driveway area for Lot "B" will be graded to drain to the north into a 2' wide x 0.5' deep gravel transition strip that borders the north side of the driveway. The runoff will then flow over a 10' wide vegetated flow path for dispersion into the surrounding soils. See attached Drainage and Erosion Control Plan for additional information. EXISTING CONDITIONS SUMMARY The site is located in the southwest comer of the intersection between S.E. l 62"d St. and 1141h Ave SE. The site was Lot I in the original short plat and it is currently vacant. It is presently covered in grass and brush. According to King County GIS, there is a topographic high point of approximately 480.00 feet situated in the southeast end of the site. The site's topography is fairly consistent sloping from east to west in Lot "B" and sloping from north to south in Lot "A". There is an approximate topographic low point of 4 75.00 feet situated in the southwest end of the site per the GIS maps. According to the Flood Insurance Rate Map (Appendix A), the site is located in a zone X, which means that it is out of the 500-year flood plain. Per the S.C.S. Soils Map, on-site soils consist of Alderwood gravelly sandy loam (8 to 15 percent slopes). This rolling Alderwood soil is moderately well drained. It formed in glacial till on broad uplands. Permeability is very slow. Surface runoff is medium, and the erosion hazard is moderate. See the SCS soils information located in the Appendix of this report for additional information. PROPOSED DEVELOPED SITE CONDITIONS SUMMARY This proposal will include the construction of two single family residences and associated driveways. The site will be split up into two separate lots, A and B. As mentioned above, the proposed driveway for Lot "A" will be off of SE 162"d St. and the proposed driveway for Lot "B" will be off of 114 1h Ave. SE. A portion of the roof runoff from Lot "A" (approximately 880 SF) and Lot "B" (approximately 100 SF) will be captured via a roof downspout tightline and conveyed to a yard drain. The runoff will then be directed to an existing 4" perforated stub-out connection and thereafter to a catch basin located in SE l 62"d St. towards the northwest end of the site. A "restricted footprint credit calculation" will be utilized to direct the remainder of roof runoff to the yards for dispersion via downspouts and splash blocks. The proposed driveway area for Lot "A" will be graded to drain to the east onto a 2' wide x 0.5' deep gravel transition strip that borders the east end of the driveway. The runoff will then flow over a 10' wide vegetated flow path for dispersion into the surrounding soils. The proposed driveway area for Lot "B" will be graded to drain to the north into a 2' wide x 0.5' deep gravel transition strip that borders the north side of the driveway. The runoff will then flow over a 10' wide vegetated flow path for dispersion into the surrounding soils. See attached Drainage and Erosion Control Plan for additional information. SECTION II -CONDITIONS AND REQUIREMENTS SUMMARY This proposal will include the connection of storm, sanitary sewer and water to the lot. Both sanitary sewer and water will be provided by Soos Creek Water and Sewer District. This report satisfies the Technical Information Report requirement to provide a written document discussion project scope. SECTION III -OFF-SITE ANALYSIS The roof runoff that will be collected by the downspout tightline system will be conveyed into an existing 4" perforated stub-out connection located in Lot "A" and then directed to existing CB # 107 in SE 162"d St. located to the northwest end of the site. It will then continue in a southwestern direction through an existing 12" pipe to the west. This existing CB and perforated stub-out connection were originally installed to accommodate runoff from Lot# 1 of the original Lund Short Plat. Since we are only conveying approximately 980 SF of runoff to it, it will easily handle the flows from this site. Stormwater created by the driveways will be collected and dispersed onsite. The site is surrounded by single family lots, so we are not anticipating any off-site runoff entering the site. SECTION IV -FLOW CONTROL AND WATER QUALITY FACILITY ANALYSIS AND DESIGN Stormwater infiltration is not feasible on this site due to the soils as depicted in the geotech results provided by Krazan (see Appendix A). Full lot dispersion of roof runoff is also not possible because of the size and layout of these lots. Flow control and water quality will therefore be mitigated utilizing the "Basic Dispersion" and "Restricted Footprint Credit" BMP's as outlined in Figure C.1.3.A, Flowchart for Determining Application of Flow Control BMP's (See Appendix A). Each driveway will utilize Basic Dispersion by being graded so as to direct surface runoff to a 2' wide by 0.5' deep gravel transition strip. The runoff will then disperse over a 10' wide vegetated flow path. In order to utilize the "Restricted Footprint Credit", the houses will be constructed with areas of approximately 1,768 SF and 1404 SF. The maximum impervious area for this R8 zone is 3,428 SF (65% of lot size). We therefore can utilize splash blocks to release some of the roof runoff to the yards. The rest of the roof runoff will be conveyed to the downspout tightline and then directed to the existing 4" perforated stub out connection located in Lot "A" before entering the catch basin located in SE 162"d Street to the northwest of our site. The catch basin was originally installed to collect runoff from the first Lund Short Plat. Since we will only be conveying runoff from approximately 1,024 SF to it. the existing system will easily accommodate it. See attached drainage and erosion control plans for more information. SECTION V -CONVEYANCE SYSTEM ANALYSIS AND DESIGN Conveyance for the lot will consist of a 4" roof downspout tightline conveyance system. The 4" pipe will connect to a tightline system that will connect to an existing catch basin in SE l 62"d St. The proposed driveways will sheet flow to the adjacent associated vegetated flow paths for dispersion purposes. The existing storm system in SE l 62"d St. was originally sized to accommodate runoff from Lot #I of the original Lund Short Plat. Since we will only be releasing runoff from approximately 980 SF to it, we know that it is adequately sized. SECTION VI -SPECIAL REPORTS AND STUDIES This section is not applicable at this time. SECTION VII -OTHER PERMITS Permits to connect to the existing storm, sanitary sewer and water systems may be required. SECTION VIII -CSWPPP ANALYSIS AND DESIGN See Appendix "B" for a complete construction SWPPP analysis and design. SECTION IX -BOND QUANTITIES, FACILITY SUMMARIES, AND DECLARATION OF COVENANT Bond Quantities will be provided at the time of engineering approval. The Declaration of Covenant will be recorded concurrently with the final short plat. No Facility Summary Form has been provided since there are no formal facilities designed for this site. SECTION X -OPERATIONS AND MAINTENANCE MANUAL See Appendix C for the complete Operations and Maintenance Manual. APPENDIX "A" MISCELLANEOUS INFORMATION LARSON & ASSOCIATES, INC. SURVEYORS, ENGINEERS AND PLANNERS 9027 PACIFIC A VENUE, SUITE 4 TACOMA, WA 98444 (253) 474-3404 A( 11/11/2015 GroaleMaps V I(. j N \TV MAP Go::igle Maps Google Maps Go},gle Map data ©2015 Google 50 ft'------' https://www .google.com/maps/@47.4579801,-122.1889169, 19z 1/1 11111/2015 Ki~ County Parcel Viewer 2.0 PAR ( f L M A P ~~==~------~--==~~----__J by:! Address I ·1 ~~r_c_t1 __ Find Intersection I Zoom to Advan ----- ·""I J1314 ! SE 162nd St S\TE ~------------- 30 60ft http"//gismaps.k1ngcounty.gov/parcelv1ewer2/?pin=00880001n 112 1111112015 King County Parcel Viewer 2 0 AERIAL MAP -------=_::_::_::_::_ __ --_-_-_-_-_ -_-_-_-_-__,-by: I Address I-I ~arch_ ,_ Find Intersection I i Zoom to http //QI sm ar=;s. k1 r,gcmmty .yov, parcel v I ewer2np1 n= 0088000177 sc.s S 0\LS \NFD~M~TlON /\S Soil Map-·-King County Area, Washington Map Unit Legend King County Area, Washington (WA633) Map Unit Symbol Map Unit Name AcreslnAOI I AgC Alderwood gravelly sandy loam, ~ ---~··-----~-8 lo 15 percent slopes ! Totals for Area of Interest L·'if).\ Natural Resources ;... Conservation Service Web Soil Survey National Cooperative Soil Survey 0.3 ----1 0,3 Percent of AOI --100.0°1 100.0% 11/11/2015 Page3of3 Map Unit Descr1pt1on Alderwood gravelly sandy loam, 8 to 15 percent slopes---King County Arca. Washington King County Area, Washington AgC-Alderwood gravelly sandy loam, 8 to 15 percent slopes LSD.·\ Natural Resources ~ Conservation Service Map Unit Setting National map unit symbol: 21626 Elevation: 50 to 800 feet Mean annual precipitation: 20 to 60 inches Mean annual air temperature: 46 to 52 degrees F Frost-free period: 160 to 240 days Farmland classification: Prime farmland if irrigated Map Unit Composition Alderwood and similar soils: 85 percent Minor components: 15 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Alderwood Setting Landform: Ridges, hills Landform position (two-dimensional): Shoulder Landform position (three-dimensional): Nose slope, tall Down-slope shape: Linear, convex Across-slope shape: Convex Parent material: Glacial drift and/or glacial outwash over dense glaciomarine deposits Typical profile A -0 to 7 inches: gravelly sandy loam Bw1 -7 to 21 inches: very gravelly sandy loam Bw2 -21 to 30 inches: very gravelly sandy loam Bg -30 to 35 inches: very gravelly sandy loam 2Cd1 -35 to 43 inches: very gravelly sandy loam 2Cd2 -43 to 59 inches: very gravelly sandy loam Properties and qualities Slope: 8 to 15 percent Depth to restrictive feature: 20 to 39 inches to densic material Natural drainage class: Moderately well drained Capacity of the most limiting layer to transmit water (Ksat): Very low to moderately low (0.00 to 0.06 in/hr) Depth to water table: About 18 to 37 inches Frequency of flooding: None Frequency of ponding: None Available water storage in profile: Very low (about 2.7 inches) Interpretive groups Land capability classification (irrigated). None specified Land capability classification (nonirrigated): 4s Hydrologic Soil Group: B Web Soil Survey National Cooperative Soil Survey Al 11/11/2015 Page 1 of 2 Map Unit Descr1pt1on Alderwood gravelly sandy loam. 8 to 15 percent slopes--King County Area, Washington Other vegetative classification: Limited Depth Soils (G002XN302WA), Limited Depth Soils (G002XS301WA), Limited Depth Soils (G002XF303WA) Minor Components Everett Percent of map unit: 5 percent Landform: Eskers, kames, moraines Landform position (two-dimensional): Shoulder, footslope Landform position (three-dimensional): Crest, base slope Down-slope shape: Convex Across-slope shape: Convex Indianola Percent of map unit: 5 percent Landform: Eskers, kames, terraces Landform position (three-dimensional): Tread Down-slope shape: Linear Across-slope shape: Linear Shalcar Percent of map unit: 3 percent Landform: Depressions Landform position {three-dimensional): Dip Down-slope shape: Concave Across-slope shape: Concave Norma Percent of map unit: 2 percent Landform: Depressions, drainageways Landform position {three-dimensional): Dip Down-slope shape: Concave, linear Across-slope shape: Concave Data Source Information Soil Survey Area: Survey Area Data: U\lH Natural Resources ;iliiiii Conservation Service King County Area, Washington Version 11, Sep 14, 2015 Web Soil Survey National Cooperative Soil Survey 11111/2015 Page 2 of 2 D- <C ~ w ~ cc. LU 0 "2. 4: ct: .=> ...,... z. 0 0 0 -' LL )F RE::,.JTON 30088 0-,;1 ~ 4 ZONE X ' VJ t:: ::;, I:] w >- <( a: 0 Cc a: 0 u CITY OF RENTON KING COUNTY ~OUP-iEAST 1_0TH STAE:[T w .... -V') ~ ~ ADPRQX1Mf'JE SCALE 1N i=EET 500 U 501J E-3::=-~~-- NATIONAL FLOOD INSURANCE PROGRAM FLOOD INSURANCE RATE MAP KING COUNTY, WASHINGTON AND INCORPORATED AREAS 'I~~ PANEL 1~ly MAP NUMBER 53033CD979 F MAP REVISED: MAY 16, 1995 This,,, an official copy of a portion of the abo""' referenced ~ood map It was extracted using F-MIT On-Line This map does not reflect changes or amendments which may hal<C been made subsequent to the date on the title block For the latE'St product 1nfofmat1on about National Flood Insurance _!:.,:_~_raITI_ flo~_~apos check the FEMA Flood Map Store at www msc ferna gov 0--- <C I C.1.3 APPLICATION OF FLOW CONTROL BMPS FIGURE C.1.3.A FLOWCHART FOR DETERMINING APPLICATION OF FLOW CONTROL BMPS ··-·--~ Is the project on a site/lot ~ Is it feasible and smaller than 22,000 square feet? I .....___,, -applicable to Yes implement full No further BMPs Apply one or more of the following to impervious area dispersion for the ---------. required. Note: ~10% of site/lot for site/lot sizes <11,000 sf and ;a 20% of roof area as per Any proposed site/lot for site/lot sizes between 11,000 and 22,000 sf (For Section C.2.1? connection of roof projects located in critical aquifer recharge areas these ®• downspouts to impervious area amounts double): local drainage 1. limited Infiltration (Section C.2.3) Is it feasible system must be I 2. Basic Dispersion (Section C.2.4)4-via perforated 3. Rain Garden (Section C.2.5) $ and applicable pipe connection 4. Permeable Pavement (Section C.2.6) to implement Yes per Section 5. Rainwater Harvesting (Section C.2. 7) full infiltration C.2.11. No 6. Vegetated Roof (Section C.2.8) of the roof ·- 7. Reduced Impervious Service Credit (Section C.2.9,.._ runoff as per 8. Native Growth Retention Credit (Section C.2.10) Section C.2.2? I Notes: No flow control BMPs are required for new pervlous s.~rfaces. . Cameli witb l11i D21t box below. _j The project must be a site/lot greater than or equal to 22,000 square feet? One or more of the following BMPs must be implemented for target impervious surface not addressed wtth full dispersion or with full infiltration of roof runoff: 1. Full Infiltration (Section C.2.2) 2. Limited Infiltration (Section C.2.3) 3. Basic Dispersion (Section C.2.4) 4. Rain Garden (Section C.2.5) 5. Permeable Pavement (Section C.2.6) 6. Rainwater Harvesting (Section C.2.7) 7. Vegetated Roof (Section C.2.8) 8. Reduced Impervious Service Credit (Section C.2.9) 9. Native Growth Retention Credit Section C.2.10 Is it feasible and applicable to implement full Yes dispersion on all target Impervious surface as per Section C.2.1? No Is it feasible and No applicable to implement full infiltration of the roof runoff as per Section C.2.2? Yes Is there any remaining target impervious surface not addressed with full dispersion or with full infiltration of roof runoff? No further BMPs required. Note: Any proposed connection of roof downspouts to local drainage system must be via perforated pipe connection per Section C.2.11. ote: ·--·---·-·-·---------------------------------~--, Flow control BMPs are required for all new pervlous surface when it exceeds 35,000 sf. Flow control BMPs must be applied in the following order of preference: 1. The feasibility and applicability of full dispersion as detailed in Section C.2.1 must be evaluated for all new pervious surfaces. 2. For those pervious surfaces not addressed in Requirement 1 above, one or more of the following BMPs must be implemented: Basic Dispersion (Section C.2.4) Rain Garden Section C.2.5 Note: == The following extra water quality prov. isions must be implemented if the project results in 5,000 sf or more of additional .pollution generating impervious surface from which runoff is not fully dispersed in accordance with Section C.2. 1; 1. Reduce existing or proposed pollution generating impervious surface so that the 5,000 sf threshold is not triggered. 2. Provide water quality facilities designed by a licensed clvll engineer in accordance with Section 1.2.8 of the SWD~~ 2009 Surface Water Design Manual -Appendix C 11912009 C-17 A-\0 LARSON AND ASSOCIATES ~.~&~ WWW.RRLARSON.COM December 8, 2015 City of Renton Development Services Renton City Hall 1055 S. Grady Way Renton, WA 98057 RE: Lund Short Plat II On-Site Soils Infiltration Capacity REPORT In order to examine the infiltration capacity of the on-site soils for Lund Short Plat 11, Larson and Associates has conducted a site visit and extracted soil logs, which have been tested by Krazan with the results that follow. Existing Site Conditions The Lund Short Plat II property is located in the southwest corner of the intersection between SE 162'' St. and 1141h Ave. SE. The site was formerly known as "Lot 1" in the original short plat and is currently vacant. The vegetation located on-site is comprised primarily of grass and brush. According to the King County GIS, there is a topographic high point of approximately 480.00 feet situated in the southeast end of the site. The property slopes from the east to west in Lot "B" and from north to south in Lot "A". There is an approximate low point of 475.00 feet situated in the southwest end of the site per the GIS maps. Existing single family residences are located on the opposite side of the road on both sides of the property. Frontage improvements were previously completed with curb, gutter and sidewalk. The proposed grades of this two-lot short plat will therefore be very close to the existing grades on and surrounding this site. S.C.S. Soils Information Per the S.C.S. Soils Map, on-site soils consist of Alderwood gravelly sandy loam (8 to 15 percent slopes). This rolling Alderwood soil is moderately well drained. It formed in glacial till on broad uplands. Permeability is very slow. Surface runoff is medium and the erosion hazard is moderate. Test Pit Information On October 15, I visited the project site where four test pits were dug to investigate the underlying soil conditions. The test pits were excavated to a width of approximately 2 feet and a depth of approximately 6 feet. Standing water was noted at approximately 2.5 feet below finish grade. I therefore extracted representative soil samples from each test pit at a depth of approximately one foot below finish grade. These soil samples were delivered to Krazan for material testing services to determine if there was any capacity in the existing soils for infiltration. Results of Krazan's testing proved that none of the test pit soils allowed for any infiltration at all. See the following soil log results for more information. 9027 Pacific Avenue. Suite 4. Tacoma, WA 98444 Office (253) 474-3404 Fax (253) 472-7358 All Conclusion Infiltration is not feasible on this site and other methods of storm water quantity control will therefore be necessary. If you have any questions regarding this information, please contact me at (253) 474-3404. ~27#!!~ President Larson & Associ Surveyors, Engineers, & Planners, Inc. A\1 a:: w z ii: f-z w 0 a:: w Cl.. 100 -~ w I I Particle Size Distribution Report I l~:I 1 : I I :1::1 :11 901-+-+--++--++-ttt--t+-tt--t-t--'n"-l+--ttt++-t--ft-t-+-+--+itt+++-t+-H-+-t-tH--tcH-t-+-+- I 11 I:!:~ I I I I I 11 1: ! 80 --,-~-~+----++-ttt-1'H -tH--t--t''t--+-;tt+f.,._.-+--+---+---tttH-+-t-t-++-t-+--ft-++-+-+-+--+n++++--+--+---1 I 1 1 I I 1 1 I I ~;l. 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I I I I I I 11 ~ I l'i 20 1----· -t--t-tt--t++-+-t--tt---t---\ I I I 1 1 I I I I I i ;: r'~!i 1, 10 1--+--+--+-+----+,-Af--t--+-ttl :--+-+--tt--t--t+-t+-Ht--t-l--f--l-tll-l+-,Hl----\--l-+--+-"-l!H-+-+----t-c----l+H-++-+-+-+------1 0 LL-'----'---._1 1 ~~ Jr'-'-'-~1:1 ~: ~ 1 ~:'-c'!!-li 1 ... ' ~ 1-'---~~-----1_,,.::w...w. lJJ-; 1 1 -'-':-'--... / ~!',:1 1 '"~-'--'--'-L.1' -'--'-i-~LW.-'-'-...L....L.~ 100 10 1 Q_1 O_D1 0.001 GRAIN SIZE· mm. %+3" % Gravel % Sand % Fines Coarse I Fine l Coarse Medium Fine Silt Clay 0.0 8.6 15.2 10.0 25.8 33.0 7.4 Test Results (C-136 & C-117) Material Description Poorly graded sand with silt and gravel. Sampled by client. Opening Percent Size Finer 1.25 100.0 1 94.2 .75 91.4 .625 90.4 .5 ' 86.9 .375 84.6 #4 76.2 #8 68.4 #10 66-2 #16 60.9 #20 58.0 #40 40.4 #60 22.5 #80 14.7 #JOO 12.5 #200 7.4 Spec."' Pass? (Percent) (X=Fall) ! Atterberg Limits (ASTM D 4318) PL= NP LL= NV Pl=_ NP Classification uses (D 2487)= SP-SM MSHTO (M 145)= A-1-b 090= 15.3996 050= 0.5802 010= 0.1117 Coefficients De5= 10.0935 030= 0.3155 Cu= 9.36 Remarks Sample ID: I 51A73 Sample Date:10-15-15 050= 1.0460 015" 0.1829 C0 = 0.85 Date Received: 10-15-15 Date Tested: 10-23-15 Tested By: _M_.Th_o_m_a_s ----~=----- Checked By: M.Thomas ~ Title: Materials Laboratory Manager (no specification provided) location: Sl.rl V<.:... Date Sampled: 10-15-15 C::~m~l6 Nu-h6r• [51A73 1UKrazan Client: Larson & Associates Project: Lund Short Platt a:: w z U:: f-z w 0 a:: w a. Particle Size Distribution Report .5 w 1DO II j T tnx\.l 111 I II '11 I I · I II 11 I I 1 :::::~=::l=:::I ::::I ::I: 11 :i==: 1 1 :1:::,.., :;l,::=::==::1::::1 =::, ::l=:, 1 ::1 :::=:=:===:::::=:=:==~ I I I I 1 1 I I i ' I ! I I I ro r++--+-+--t+t1++-11 i-+++--tJ1:----1~+H+1-+\.,'-i-l-----t-ll-f+++++--+-+-+--+-1tt+t-+-t-+--+-+-------,H--H+++-1----1--1 I I I : 1 1 : I r: r\. 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I :: it : I I I 0 LL---'----L---'----,-!-oo=-'-'---"-.u...--"-----'--,c'!o!-'-'-.J....11--'--'---'---'-,=.J..J.-"-.w..--'---+--'~!'-.1..w..w..--'---"---'-~o.L.ou1 .u...L.J.-+-_,__o_-00-'1 GRAIN SIZE -mm. %+3'" I % Gravel I I Coarse ! Fine Coarse 0.0 I 0.0 14.3 19. I Test Results (C-136 & C-117) Opening Size 1 .75 .625 .5 .375 #4 #8 #10 #16 #20 #40 #60 #80 #100 #200 i I Percent Finer 100.0 100.0 97.5 96.8 93.8 85.7 70.9 66.6 57.4 53.1 37.8 25.6 19.4 17.0 11.0 (no spec1ficat10n provided) Spec.• (Percent) Pass? (X=Fall) %Sand I % Fines Medium I Fine Slit 28.8 I 26.8 11.0 Material Description Poorly graded sand with silt. Sampled by client. Atterberg Limits (ASTM D 4318j PL= NP LL= NV Pl= NP Classification uses (0 2487)= SP-SM AASHTO (M 145)-A-1-b D90= 6.7508 Dso= 0.7153 D10= Coefficients D55= 4.5428 D30= 0.3059 Cu= Remarks Sample ID: 151474 Sample Date: I 0-15-15 0 60= 1.4194 D15= 0.1242 Cc= Clay Date Received: 10-15-15 Date Tested: 10-23-15 Tested By: _M_.Th_o_m_a_s -~------------- Checked By: M.Thomas .,,..__ P~ Title: Materials Laboratory Manager k~!;!'~i~n~J~Lr-151474 Date Sampled: 10-15-15 ~Krazan Client: Larson & Associates Project: Lund Short Platt "ti,nlact No: n,;i;_ 1 <1>< ] Cl'. w z Li: 1-z w ~ w 11. Particle Size Distribution Report 100 1r T 1 1 1 r , 1 , 11 ' I . I I I I ! i 90 1-+--1-------W-sl+++--l.---l--<-H-!~=..J1'1U--l---1-----U.l-W.--14-l-----+--+,-J-l-hl-W--l-l--1--W-W---l-l---l---i-J_---I I I I I I I I iii\ I I I I I j aoLL-l-_l_i___LJ_JlllJ_L..JJ_L_!-Jl__J__JU_LU_._JLLJ.__J _ _J_ill.LLLJL_jW--1---j-~+t+t++-+-+-+--+++-1-H-l---+-+------1 ! I I ! I ! I 1 I I ! ! !1 I I 70 H--l----+-+--++IIH+-1+-++-1<-l-#lft+H+-+----l----\l------l-lll+++-ll-t-+-+-!-41+t+t++-+-+-+--+++-t++-+-+-+------I ! I I ! r! ! !I I \ I ! ! ! ! 60 ' ' -+_l-l+JL!+4---!L-W---JL-'--14--1++-IL+-+---+-\--Wl+++-f--+'-+_[_--4++4-1+-l-+---+----l++,4--l--/-----1----I I 11 I I I I 11 1 1 1 \. 1 1 I I 1 1 1 .1 1 ' I I I I I I I I Q I 11 11 5o1-+--1----+-il---1-WWI ---1---1---JL-I +'-I -ll-~l--1+1--1-; -1--1-e----""l.-l!U--W--'J.I --+-'-I -i--'1--";I +!!1-l---l---l---l-+--l-+-i-W-1--I--J_+------1 I I I I I I I I I I I I I 40 LL-1------'--'-1 --lJ..U++-+--l----+ l-l-'--l--W-'---l.-+-l-1------+.CU~~--i--IJ-+~1-+-~ l,H-tlcl-+H---l--+--+h-++-i--1-----!-----!-----i I I I I I I I I I 'r I I I 301-+--1---1-~-1-1--4l---+-j--1,--1--+---J.---+-~l~--1---1---1-------1-1.U-W-.l'I -.-1"--+--l-+I, -,+ii i-rti-4--l--i-----1---+-1-W+-l-+-'--'-----1 I I I I I I I I I " 20H--+--++----l+-lll-l-i--ll--++-fl----l-l-l-++-Hl-+----l-l------l-lll-+++~-+-+-OJ---+1++11++-+-+-+--+++1-H-+-+--I-------I ! JI I I I ! I I I ! ! -f" 1 O U--'---+--1-----W-ll-W~-l--l---l--,e----l-l-el+-Wl--l--l-l----l-lll--l-W--ll--LL-1--1---+f+-m---1-1---1--+-+---I--W-1-H-'-+-+------I ! I! 1! ! I ! i' I I ! I! ! I 1: 0 LL-'--'--'--.-J1o'""o!ll..J....L.J'--'--'-''--'-10!0cu_L1L-'----'-'-----'1=.w.JJ....'-'--'---'---!-o."1 ilLl....L.J-'--'--~o.'='01,u.,...1.__L...J..---+-0-.00"""1 GRAIN SIZE -mm. l %Gravel ' %+3" I Coarse Fine I Coarse I 0.0 1 2.6 8.7 Opening Size I .75 .5 .375 #4 #8 #10 #16 #20 #40 #60 #80 #100 #200 Test Results (C-136 & C-117) Percent Finer 100.0 97.4 95.1 93.0 88.7 73.3 66.6 52.9 47.1 33.2 25.0 20.4 17.9 12.5 Spec.* (Percent) * (no specification provided) Pass? (X=Fall) 22.1 •;;. Sand Medium I Fine 33.4 I 20.7 Silty sand. Sampled by client. % Fines Silt I 12.5 Atterberg Limits (ASTM D 4318) PL= NP LL= NV Pl= NP Classlflcatlon uses (D 2487)= SM AASHTO (M 145)= A-1-b Dgo= 5.5877 D50= 1.0005 D10= Coefficients Ds5= 3.6108 D30= 0.3521 Cu= Remarks Sample ID:15IA75 Sample Date:10-15-15 Dao= 1.6350 D15= 0.1107 Cc= Clay Date Received: 10-15-15 Date Tested: 10-23-15 Tested By: M.Thomas Checked By: M.Thomas ~&IIJi&~ Title: Materials Laboratory Manager ~~~a~!~'?.;.~~L. I" ,m Date Sampled: 10-15-15 Client: Larson & Associates ~lilKr-azari Project: Lund Short Platt A\S Particle Size Distribution Report " . D 'ii D .s .s ~ ~ ~ ~ ; i :t D ~ ~ ;I !I ; ;; ~ w ~ ~ 100 I 1: :n1 I I I, I I I I I '.l,i I I I I I 90 : i; I ' I I I I i I I I I I \ I I' I I I I 80 ~ ! I I I I I I I I I I I I I I I 70 o:'. I I 1: I I I I I " I I I I I I w I I I 11 I I z 60 ,I I 'i . u:: I I· I I I I I I I II I f-50 I I I I I I I I I I I I I I z I I I I I I I I I I I ! I UJ 0 I I I I I I I I I I I I I o:'. 40 I I I 1: I I :1 ' I w r.. a.. I I I I I I I I \ I I I 30 II I I 1; I', I I II I I I I I I ! II I 'a,~ I I I 20 1: I I I I 1! I I Ii I I ! ~· I 10 I lj I I I I !1 I 1:1 I I I I I 0 I I Ii I I I I ! 100 10 1 0.1 0.01 0.001 GRAIN SIZE -mm. %+3" % Gravel %Sand % Fines Coarse Fine Coarse Medium I Fine Silt I Clay 0.0 3.0 3.6 23.2 I 39.1 I 19.5 11.6 Test Results (C-136 & C-117) Mi!terii!I ~escri12tlon Opening Percent Spec.* Pass? Poorly graded sand with silt Size Finer (Percent) (X•Fail) Sampled by client. 1 100.0 .75 97.0 Atterberg Limits (ASTM D 4318) .5 96.5 PL= NP LL= NV Pl= NP .375 95.1 #4 93.4 Classification #8 77.4 uses (D 2487)= SP-SM AASHTO (M 145)= A-1-b #10 70.2 ~1!! #16 59.3 D90= 3.5838 D85= 2.8997 Dao= 1.2112 lt20 46.2 D50= 0.9327 D30= 0.3962 D15= 0.1309 #40 31.1 D10= Cu= Cc= #60 23.4 #80 19.8 I Remarks #100 16.8 Sample ID: I 5IA 7 6 #200 11.6 Sample Date:10-15-15 Date Received: I 0-15-15 Date Tested: 10-23-15 Tested By: M.Thomas Checked By: M.Thomas ,;::,:..,::!!ii?r,~~ Title: Materials Laboratol)' Manager .,.. (no specification provided) !,ocation: SL-4 476 vc.. Date Sam pied: 10-15-15 Client: Larson & Associates Q'l)Krazan Project: L=d Short Platt ' t>.;.sa~, "'~· Jlli,;..1,,76 i=i ... t.ire . A lb APPENDIX "B" CONSTRUCTION SWPPP AND BMP'S LARSON & ASSOCIATES, INC. SURVEYORS, ENGINEERS AND PLANNERS 9027 PACIFIC AVENUE, SUITE 4 TACOMA, WA 98444 (253) 474-3404 sro~ WATER POLLU;''('lON" ~ 0 B.BV,ENTI ON. PL,.AJN SECTION I -CONSTRUCTION STORMWATER POLLUTION PREVENTION ELEMENTS Stormwater pollution prevention will be maintained during the construction of this site by incorporating standard erosion control methods such as a temporary construction entrance and mirafi siltation fences. The following devices will be used to trap sediment from the cleared areas and prevent it from leaving the site. A construction entrance will be installed at the entrance to the site to keep sediment from being tracked out of the site and onto the City roads. Mirafi silt fences will be installed along the perimeter to stop any sediment runoff from exiting the project limits. The following general Washington State Elements shall be upheld at all times during the construction process. Please reference the BMP section in this report. Element #1: Preserve Vegetation/Mark Clearing Limits • Prior to beginning land disturbing activities, including clearing and grading, clearly mark all clearing limits, sensitive areas and their buffers, and trees that are to be preserved within the construction area. These shall be marked, both in the field and on the plans, to prevent damage and offsite impacts. • The duff layer, native topsoil, and natural vegetation shall be retained in an undisturbed state to the maximum degree practicable. • Plastic, metal, or stake wire fence may be used to mark the clearing limits. • Suggested BMPs: BMP Cl 03: High Visibility Plastic or Metal Fence BMP C104: Stake and Wire Fence Element #2: Establish Construction Access • Construction vehicle access and exit shall be limited to one route, if possible. • Access points shall be stabilized with a pad of quarry spalls, crushed rock or other equivalent BMP, to minimize the tracking of sediment onto public roads. • Wheel wash or tire baths should be located on site, if the stabilized construction entrance is not effective in preventing sediment from being tracked onto public roads. • If sediment is tracked off site, public roads shall be cleaned thoroughly at the end of each day, or more frequently during wet weather. Sediment shall be removed from roads by shoveling or pickup sweeping and shall be transported to a controlled sediment disposal area. • Street washing is allowed only after sediment is removed in accordance with S9.D.2.d. Street wash wastewater shall be controlled by pumping back on site or otherwise be prevented from discharging into systems tributary to waters of the state. • Construction access restoration shall be equal to or better than the pre- construction condition. • Suggested BMPs: BMP CI05: Stabilized Construction Entrance Element #3: Control Flow Rates This is not applicable to this proposal as all stormwater from the proposed residence and driveway will be controlled onsite with the use of "dispersion" methods. Element #4: Install Sediment Controls This will not be applicable to this proposal due to the large vegetated buffer that will remain onsite undisturbed around the construction area. Element #5: Stabilize Soils • Exposed and unworked soils shall be stabilized by application of effective BMPs that prevent erosion. Applicable BMPs include, but are not limited to: temporary and permanent seeding, sodding, mulching, plastic covering, erosion control fabrics and matting, soil application of polyacrylamide (PAM), the early application of gravel base on areas to be paved, and dust control. • Depending on the geographic location of the project, no soils shall remain exposed and unworked for more than the time periods set forth below to prevent erosion: West of the Cascade Mountains Crest: During the dry season (May I -Sept. 30): 7 days During the wet season (October I -April 30): 2 days The time period may be adjusted by a local jurisdiction, if the Jurisdiction can show that local precipitation data justify a different standard. • Soils shall be stabilized at the end of the shift before a holiday or weekend if needed based on the weather forecast. • Soil stockpiles must be stabilized from erosion, protected with sediment trapping measures, and where possible, be located away from storm drain inlets, waterways, and drainage channels. • Suggested BMPs: BMPC120: BMP Cl2I: BMPCI24: BMPCl25: BMPCISO: Temporary and Permanent Seeding Mulching Sodding Topsoiling Small Project Construction Stormwater Pollution Prevention Element #6: Protect Slopes • Design and construct cut and fill slopes in a manner that will minimize erosion. Applicable practices include, but are not limited to, reducing continuous length of slope with terracing and diversions, reducing slope steepness, and roughening slope surfaces ( e.g., track walking). • Off-site stormwater (run-on) or groundwater shall be diverted away from slopes and disturbed areas with interceptor dikes, pipes, and/or swales. Off-site stormwater should be managed separately from stormwater generated on the site. • At the top of slopes, collect drainage in pipe slope drains or protected channels to prevent erosion. West of the Cascade Mountains Crest: Temporary pipe slope drains shall handle the peak 10-minute velocity of flow from a Type IA, IO-year, 24-hour frequency storm for the developed condition. Alternatively, the 10-year, I-hour flow rate predicted by an approved continuous runoff model, increased by a factor of 1.6, may be used. The hydro logic analysis shall use the existing land cover condition for predicting flow rates from tributary areas outside the project limits. For tributary areas on the project site, the analysis shall use the temporary or permanent project land cover condition, whichever will produce the highest flow rates. If using the WWHM to predict flows, bare soil areas should be modeled as "landscaped area." • Excavated material shall be placed on the uphill side of trenches, consistent with safety and space considerations. • Check dams shall be placed at regnlar intervals within constructed channels that are cut down a slope. • Suggested BMPs: BMP Cl 20: Temporary and Permanent Seeding BMP Cl21: Mulching Element #7: Protect Drain Inlets • All storm drain inlets made operable during construction shall be protected so that stormwater runoff does not enter the conveyance system without first being filtered or treated to remove sediment. • Inlet protection devices shall be cleaned or removed and replaced when sediment has filled one-third of the available storage (unless a different standard is specified by the product manufacturer). • Suggested BMPs: BMP C220: Storm Drain Inlet Protection Element #8: Stabilize Channels and Outlets This is not applicable to this proposal as all stormwater from the proposed residence and driveway will be controlled onsite with the use of"dispersion" methods. Element #9: Control Pollutants • All pollutants, including waste materials and demolition debris, that occur on site during construction shall be handled and disposed of in a manner that does not cause contamination of surface water. • Cover, containment, and protection from vandalism shall be provided for all chemicals, liquid products, petroleum products, and other materials that have the potential to pose a threat to human health or the environment. On-site fueling tanks shall include secondary containment. • Maintenance, fueling, and repair of heavy equipment and vehicles shall be conducted using spill prevention and control measures. Contaminated surfaces shall be cleaned immediately following any spill incident. • Wheel wash or tire bath wastewater shall be discharged to a separate on-site treatment system or to the sanitary sewer with local sewer district approval. • Application of fertilizers and pesticides, shall be conducted in a manner and at application rates that will not result in loss of chemical to stormwater runoff. Manufacturers' label requirements for application rates and procedures shall be followed. • BMPs shall be used to prevent or treat contamination of storm water runoff by pH modifying sources. These sources include, but are not limited to: bulk cement, cement kiln dust, fly ash, new concrete washing and curing waters, waste streams generated from concrete grinding and sawing, exposed aggregate processes, dewatering concrete vaults, concrete pumping and mixer washout waters. Permittees shall adjust the pH of stonnwater if necessary to prevent violations of water quality standards. • Permittees shall obtain written approval from Ecology prior to using chemical treatment, other than CO2 or dry ice to adjust pH. • Suggested BMPs: BMP C 151: Concrete Handling Element #10: Control Dewatering This is not applicable to this proposal due to only a small portion of the total parcel area being developed and all stormwater being controlled onsite through "dispersion" methods. Element #11: Maintain BMPs • All temporary and permanent erosion and sediment control BMPs shall be maintained and repaired as needed to assure continued performance of their intended function in accordance with BMP specifications. • All temporary erosion and sediment control BMPs shall be removed within 30 days after final site stabilization is achieved or after the temporary BMPs are no longer needed. Element #12: Manage the Project • Development projects shall be phased to the maximum degree practicable and shall take into account seasonal work limitations. • Inspection and Monitoring All BMPs shall be inspected, maintained, and repaired as needed to assure continued performance of their intended function. Site inspections and monitoring shall be conducted in accordance with S4. • Maintaining an Updated Construction SWPPP The SWPPP shall be maintained, updated, and implemented in accordance with Conditions S3, S4 and S9. Monitoring Requirements The primary monitoring requirements are summarized in Table 3 (below): Table 3. Summary ofl\fonitorinl!: ReQuiremcnts' Size of Soils Disturbance, Weekly Weekly Weekly Weekly Site Sampling Samplingw/ pH Inspections w/ Transparency sampling 3 Turbidity Tube Meter Sites which disturb less Required Not Not Required Not than I acre Required Required Sites which disturb 1 acre Sampling Required-either or more, but less than 5 Required method4 Required acres Sites which disturb 5 acres Required Required Not Required or more Required5 1 Additional monitoring requirements may apply for: I) discharges to 303(d) listed waterbodies and waterbodies with applicable TMDLs for turbidity, fine sediment, high pH, or phosphorus -see Condition S8; and 2) sites required to perform additional monitoring by Ecology order -see Condition G 13. 2 Soil disturbance is calculated by adding together all areas affected by construction activity. Construction Activity means clearing, grading, excavation, and any other activity which disturbs the surface of the land, including ingress/egress from the site. 3 Beginning October I, 2006, if construction activity involves significant concrete work or the use of engineered soils, and stormwater from the affected area drains to a stormwater collection system or other surface water, the Permittee shall conduct pH sampling in accordance with Condition S4.D. 4 Beginning October I, 2008, sites with one or more acres, but Jess than 5 acres of soil disturbance, shall conduct turbidity or transparency sampling in accordance with Condition S4.C. 5 Beginning October I, 2006, sites greater than or equal to 5 acres of soil disturbance shall conduct turbidity sampling using a turbidity meter in accordance with Condition S4.C. A. Site Log Book The Permittee shall maintain a site log book that contains a record of the implementation of the SWPPP and other permit requirements including the installation and maintenance ofBMPs, site inspections, and stormwater monitoring. B. Site Inspections I. Site inspections shall include all areas disturbed by construction activities, all BMPs, and all stonnwater discharge points. Stonnwater shall be visually examined for the presence of suspended sediment, turbidity, discoloration, and oil sheen. Inspectors shall evaluate the effectiveness of BMPs and determine if it is necessary to install, maintain, or repair BMPs to improve the quality of stormwater discharges. Based on the results of the inspection, the Permittee shall correct the problems identified as follows: a. Review the SWPPP for compliance with Condition S9 and make appropriate revisions within 7 days of the inspection; and b. Fully implement and maintain appropriate source control and/or treatment BMPs as soon as possible, but no later than 10 days of the inspection; and c. Document BMP implementation and maintenance in the site log book. 2. The site inspections shall be conducted at least once every calendar week and within 24 hours of any discharge from the site. The inspection frequency for temporarily stabilized, inactive sites may be reduced to once every calendar month. 3. Site inspections shall be conducted by a person who is knowledgeable in the principles and practices of erosion and sediment control. The inspector shall have the skills to: a. Assess the site conditions and construction activities that could impact the quality of stormwater, and b. Assess the effectiveness of erosion and sediment control measures used to control the quality of stormwater discharges. 4. Beginning October I, 2006, construction sites one acre or larger that discharge storm water to surface waters of the state, shall have site inspections conducted by a Certified Erosion and Sediment Control Lead (CESCL). The CESCL shall be identified in the SWPPP and shall be present on-site or on-call at all times. Certification shall be obtained through an approved erosion and sediment control training program that meets the minimum training standards established by Ecology (see BMP C160 in the Manual). 5. The inspector shall summarize the results of each inspection in an inspection report or checklist and be entered into, or attached to, the site log book. At a minimum, each inspection report or checklist shall include: a. Inspection date and time. b. Weather information; general conditions during inspection and approximate amount of precipitation since the last inspection, and within the last 24 hours. c. A summary or list of all BMPs which have been implemented, including observations of all erosion/sediment control structures or practices. d. The following shall be noted: i. locations ofBMPs inspected, 11. locations ofBMPs that need maintenance, iii. the reason maintenance is needed, iv. locations ofBMPs that failed to operate as designed or intended, and v. locations where additional or different BMPs are needed, and the reason(s) why. e. A description of stormwater discharged from the site. The inspector shall note the presence of suspended sediment, turbid water, discoloration, and/or oil sheen, as applicable. f. Any water quality monitoring performed during inspection. g. General comments and notes, including a brief description of any BMP repairs, maintenance or installations made as a result of the inspection. h. A statement that, in the judgment of the person conducting the site inspection, the site is either in compliance or out of compliance with the terms and conditions of the SWPPP and the permit. If the site inspection indicates that the site is out of compliance, the inspection report shall include a summary of the remedial actions required to bring the site back into compliance, as well as a schedule of implementation. i. Name, title, and signature of the person conducting site inspection; and the following statement: "I certify that this report is true, accurate, and complete, to the best of my knowledge and belief'. BMP'S LARSON & ASSOCIATES, INC. SURVEYORS, ENGINEERS AND PLANNERS 9027 PACIFIC A VENUE, SUITE 4 TACOMA, WA 98444 (253) 474-3404 I? I\ BMP C103: High Visibility Plastic or Metal Fence Purpose Conditions of Use Design and I11stallatio11 Specifications Mai11te11a11ce Sta11dards 4-6 Fencing is intended to: (I) restrict clearing to approved limits; (2) prevent distnrbance of sensitive areas, their buffers, and other areas required to be left undisturbed; (3) limit construction traffic to designated construction entrances or roads; and, ( 4) protect areas where marking with survey tape may not provide adequate protection. To establish clearing limits, plastic or metal fence may be used: At the boundary of sensitive areas, their buffers, and other areas required to be left uncleared. As necessary to control vehicle access to and on the site. High visibility plastic fence shall be composed of a high-density polyethylene material and shall be at least four feet in height. Posts for the fencing shall be steel or wood and placed every 6 feet on center (maximum) or as needed to ensure rigidity. The fencing shall be fastened to the post every six inches with a polyethylene tie. On long continuous lengths of fencing, a tension wire or rope shall be used as a top stringer to prevent sagging between posts. The fence color shall be high visibility orange. The fence tensile strength shall be 360 lbs./ft. using the ASTM D4595 testing method. Metal fences shall be designed and installed according to the manufacturer's specifications. Metal fences shall be at least 3 feet high and must be highly visible. Fences shall not be wired or stapled to trees. If the fence has been damaged or visibility reduced, it shall be repaired or replaced immediately and visibility restored. Volume II -Construction Stormwater Pollution Prevention February 2005 BMP C104: Stake and Wire Fence Purpose Conditions of Use Design and Installation Specifications Maintenance Standards February 2005 Fencing is intended to: (I) restrict clearing to approved limits; (2) prevent disturbance of sensitive areas, their buffers, and other areas required to be left undisturbed; (3) limit construction traffic to designated construction entrances or roads; and, ( 4) protect any areas where marking with survey tape may not provide adequate protection. To establish clearing limits, stake or wire fence may be used: At the boundary of sensitive areas, their buffers, and other areas required to be left uncleared. As necessary, to control vehicle access to and on the site. See Figure 4.1 for details. More substantial fencing shall be used if the fence does not prevent encroachment into those areas that are not to be disturbed. If the fence has been damaged or visibility reduced, it shall be repaired or replaced immediately and visibility restored. Survey Flagging Baling Wire Do Not Nail or Staple Wire to Trees Figure 4.1 -Stake and Wire Fence Volume II -Construction Stormwater Pollution Prevention Metal Fence Post 4-7 BMP C105: Stabilized Construction Entrance Purpose Construction entrances are stabilized to reduce the amount of sediment transported onto paved roads by vehicles or equipment by constructing a stabilized pad of quarry spalls at entrances to construction sites. Conditions of Use Construction entrances shall be stabilized wherever traffic will be leaving a construction site and traveliog on paved roads or other paved areas within 1,000 feet of the site. Design and Installation Specifications 4-8 On large commercial, highway, and road, projects, the designer should include enough extra materials in the ":On.tract to allow for additional stabilized entrances not shown in tlie:initial Construction SWPPP. It is difficult to determine exactly_ where access to these projects will take place; additional materials WJll enable the contractor to install them where needed. See Figure 4.2 for details. Note: the 100' minimum length of the entrance shall be reduced to the maximum practicable size when the size or configuration of the site does not allow the full length (100'). A separation geotextile shall be placed under the spalls to prevent fine sediment from pumping up into the rock pad. The geotextile shall meet the following standards: Grab Tensile Strength (ASTM D4751) 200 psi min. Grab Tensile Elongation (ASTM D4632) 30% max. Mullen Burst Strength (ASTM D3786-80a) 400 psi min. AOS (ASTM D4751) 20-45 (U.S. standard sieve size) Consider early installation of the first lift of asphalt in areas that will paved; this can be used as a stabilized entrance. Also consider the installation of excess concrete as a stabilized entrance. During large concrete pours, excess concrete is often available for this purpose. Hog fuel (wood-based mulch) may be substituted for or combined with quarry spalls in areas that will not be used for permanent roads. Hog fuel is generally less effective at stabilizing construction entrances and should be used only at sites where the amount of traffic is very limited. Hog fuel is not recommended for entrance stabilization in urban areas. The effectiveness of hog fuel is highly variable and it generally requires more maintenance than quarry spalls. The inspector may at any time require the use of quarry spalls if the hog fuel is not preventing sediment from being tracked onto pavement or if the hog fuel is being carried onto pavement. Hog fuel is prohibited in permanent roadbeds because organics in the subgrade soils cause degradation of the subgrade support over time. Fencing (see BMPs Cl03 and C104) shall be installed as necessary to restrict traffic to the construction entrance. Volume II -Construction Stormwater Pollution Prevention February 2005 Maintenance Standards February 2005 Whenever possible, the entrance shall be constructed on a firm, compacted subgrade. This can substantially increase the effectiveness of the pad and reduce the need for maintenance. Quarry spalls ( or hog fuel) shall be added if the pad is no longer in accordance with the specifications. • If the entrance is not preventing sediment from being tracked onto pavement, then alternative measures to keep the streets free of sediment shall be used. This may include street sweeping, an increase in the dimensions of the entrance, or the installation of a wheel wash. Any sediment that is tracked onto pavement shall be removed by shoveling or street sweeping. The sediment collected by sweeping shall be removed or stabilized on site. The pavement shall not be cleaned by washing down the street, except when sweeping is ineffective and there is a threat to public safety. If it is necessary to wash the streets, the construction of a small sump shall be considered. The sediment would then be washed into the sump where it can be controlled. Any quarry spalls that are loosened from the pad, which end up on the roadway shall be removed innnediately. • If vehicles are entering or exiting the site at points other than the construction entrance(s), fencing (see BMPs Cl03 and C104) shall be installed to control traffic. Upon project completion and site stabilization, all construction accesses intended as permanent access for maintenance shall be ermanently stabilized. Driveway shall meet the requirements of the permittingllgency lllsrecammend11dthat lheenl!ancebe crowned so that runoff dralnsotlthepad Figure 4.2 -Stabilized Construction Entrance Volume II -Construction Stormwater Pollution Prevention 4-9 BMP C120: Temporary and Permanent Seeding Purpose Conditions of Use Design and Installation Specifications February 2005 Seeding is intended to reduce erosion by stabilizing exposed soils. A well-established vegetative cover is one of the most effective methods of reducing erosion. Seeding may be used throughout the project on disturbed areas that have reached final grade or that will remain unworked for more than 30 days. Channels that will be vegetated should be installed before major earthwork and hydroseeded with a Bonded Fiber Matrix. The vegetation should be well established (i.e., 75 percent cover) before water is allowed to flow in the ditch. With channels that will have high flows, erosion control blankets should be installed over the hydroseed. If vegetation cannot be established from seed before water is allowed in the ditch, sod should be installed in the bottom of the ditch over hydromulch and blankets. Retention/ detention ponds should be seeded as required. • Mulch is required at all times because it protects seeds from heat, moisture loss, and transport due to runoff. • All disturbed areas shall be reviewed in late August to early September and all seeding should be completed by the end of September. Otherwise, vegetation will not establish itself enough to provide more than average protection. • At final site stabilization, all disturbed areas not otherwise vegetated or stabilized shall be seeded and mulched. Final stabilization means the completion of all soil disturbing activities at the site and the establishment of a permanent vegetative cover, or equivalent permanent stabilization measures ( such as pavement, riprap, gabions or geotextiles) which will prevent erosion. Seeding should be done during those seasons most conducive to growth and will vary with the climate conditions of the region. Local experience should be used to determine the appropriate seeding periods. The optimum seeding windows for western Washington are April 1 through June 30 and September 1 through October 1. Seeding that occurs between July 1 and August 30 will require irrigation until 75 percent grass cover is established. Seeding that occurs between October 1 and March 30 will require a mulch or plastic cover until 7 5 percent grass cover is established. To prevent seed from being washed away, confirm that all required surface water control measures have been installed. Volume II -Construction Stormwater Pollution Prevention 4-13 B \(o 4-14 The seedbed should be firm and rough. All soil should be roughened no matter what the slope. If compaction is required for engineering purposes, slopes must be track walked before seeding. Backblading or smoothing of slopes greater than 4: 1 is not allowed if they are to be seeded. New and more effective restoration-based landscape practices rely on deeper incorporation than that provided by a simple single-pass rototilling treatment. Wherever practical the subgrade should be initially ripped to improve long-term permeability, infiltration, and water inflow qualities. At a minimum, permanent areas shall use soil amendments to achieve organic matter and permeability performance defined in engineered soil/landscape systems. For systems that are deeper than 8 inches the rototilling process should be done in multiple lifts, or the prepared soil system shall be prepared properly and then placed to achieve the specified depth. Organic matter is the most appropriate form of "fertilizer" because it provides nutrients (including nitrogen, phosphorus, and potassium) in the least water-soluble form. A natural system typically releases 2-10 percent of its nutrients annually. Chemical fertilizers have since been formulated to simulate what organic matter does naturally. In general, 10-4-6 N-P-K (nitrogen-phosphorus-potassium) fertilizer can be used at a rate of90 pounds per acre. Slow-release fertilizers should always be used because they are more efficient and have fewer environmental impacts. It is recommended that areas being seeded for final landscaping conduct soil tests to determine the exact type and quantity of fertilizer needed. This will prevent the over-application of fertilizer. Fertilizer should not be added to the hydromulch machine and agitated more than 20 minutes before it is to be used. If agitated too much, the slow-release coating is destroyed. There are numerous products available on the market that take the place of chemical fertilizers. These include several with seaweed extracts that are beneficial to soil microbes and organisms. If 100 percent cottonseed meal is used as the mulch in hydroseed, chemical fertilizer may not be necessary. Cottonseed meal is a good source of long-term, slow-release, available nitrogen. Hydroseed applications shall include a minimum of 1,500 pounds per acre of mulch with 3 percent tackifier. Mulch may be made up of 100 percent: cottonseed meal; fibers made of wood, recycled cellulose, hemp, and kenaf; compost; or blends of these. Tackifier shall be plant- based, such as guar or alpha plantago, or chemical-based such as polyacrylamide or polymers. Any mulch or tackifier product used shall be installed per manufacturer's instructions. Generally, mulches come in 40-50 pound bags. Seed and fertilizer are added at time of application. Volume II -Construction Stormwater Pollution Prevention February 2005 [517 February 2005 Mulch is always required for seeding. Mulch can be applied on top of the seed or simultaneously by hydroseeding. On steep slopes, Bonded Fiber Matrix (BFM) or Mechanically Bonded Fiber Matrix (MBFM) products should be used. BFM/MBFM products are applied at a minimum rate of 3,000 pounds per acre of mulch with approximately 10 percent tackifier. Application is made so that a minimum of95 percent soil coverage is achieved. Numerous products are available commercially and should be installed per manufacturer's instructions. Most products require 24-36 hours to cure before a rainfall and cannot be installed on wet or saturated soils. Generally, these products come in 40-50 pound bags and include all necessary ingredients except for seed and fertilizer. BFMs and MBFMs have some advantages over blankets: • No surface preparation required; Can be installed via helicopter in remote areas; • On slopes steeper than 2.5:1, blanket installers may need to be roped and harnessed for safety; They are at least $1,000 per acre cheaper installed. In most cases, the shear strength of blankets is not a factor when used on slopes, only when used in channels. BFMs and MBFMs are good alternatives to blankets in most situations where vegetation establishment is the goal. • When installing seed via hydroseeding operations, only about 1/3 of the seed actually ends up in contact with the soil surface. This reduces the ability to establish a good stand of grass quickly. One way to overcome this is to increase seed quantities by up to 50 percent. • Vegetation establishment can also be enhanced by dividing the hydromulch operation into two phases: 1. Phase 1-Install all seed and fertilizer with 25-30 percent mulch and tackifier onto soil in the first lift; 2. Phase 2-Install the rest of the mulch and tackifier over the first lift. An alternative is to install the mulch, seed, fertilizer, and tackifier in one lift. Then, spread or blow straw over the top of the hydro mulch at a rate of about 800-1000 pounds per acre. Hold straw in place with a standard tackifier. Both of these approaches will increase cost moderately but will greatly improve and enhance vegetative establishment. The increased cost may be offset by the reduced need for: 1. Irrigation 2. Reapplication of mulch 3. Repair of failed slope surfaces Volume ff -Construction Stormwater Pollution Prevention 4-15 4-16 This technique works with standard hydromulch (1,500 pounds per acre minimum) and BFM/MBFMs (3,000 pounds per acre minimum). Areas to be permanently landscaped shall provide a healthy topsoil that reduces the need for fertilizers, improves overall topsoil quality, provides for better vegetal health and vitality, improves hydrologic characteristics, and reduces the need for irrigation. This can be accomplished in a number of ways: Recent research has shown that the best method to improve till soils is to amend these soils with compost. The optimum mixture is approximately two parts soil to one part compost. This equates to 4 inches of compost mixed to a depth of 12 inches in till soils. Increasing the concentration of compost beyond this level can have negative effects on vegetal health, while decreasing the concentrations can reduce the benefits of amended soils. Please note: The compost should meet specifications for Grade A quality compost in Ecology Publication 94-038. Other soils, such as gravel or cobble outwash soils, may require different approaches. Organics and fines easily migrate through the loose structure of these soils. Therefore, the importation of at least 6 inches of quality topsoil, underlain by some type of filter fabric to prevent the migration of fines, may be more appropriate for these soils. Areas that already have good topsoil, such as undisturbed areas, do not require soil amendments. Areas that will be seeded only and not landscaped may need compost or meal-based mulch included in the hydroseed in order to establish vegetation. Native topsoil should be re-installed on the disturbed soil surface before application. Seed that is installed as a temporary measure may be installed by hand if it will be covered by straw, mulch, or topsoil. Seed that is installed as a permanent measure may be installed by hand on small areas (usually less than I acre) that will be covered with mulch, topsoil, or erosion blankets. The seed mixes listed below include recommended mixes for both temporary and permanent seeding. These mixes, with the exception of the wetland mix, shall be applied at a rate of 120 pounds per acre. This rate can be reduced if soil amendments or slow- release fertilizers are used. Local suppliers or the local conservation district should be consulted for their recommendations because the appropriate mix depends on a variety offactors, including location, exposure, soil type, slope, and expected foot traffic. Alternative seed mixes approved by the local authority may be used. Volume II -Construction Stormwater Pollution Prevention February 2005 February 2005 Table 4.1 represents the standard mix for those areas where just a temporary vegetative cover is required. Table 4.1 Temoorary Erosion Control Seed Mix %WeiE!bt %Purity % Germination Chewings or annual blue grass 40 98 90 Festuca rubra var. commutata or Poa anna Perennial rye -50 98 90 Lolium verenne Redtop or colonial bentgrass 5 92 85 Ar,rostis alba or Ar,rostis tenuis White dutch clover 5 98 90 Trifolium repens Table 4.2 provides just one recommended possibility for landscaping seed. Table 4.2 Landscaping Seed Mix o/0Wei2ht 0/o Purity % Germination Perennial rye blend 70 98 90 Lolium perenne Chewings and red fescne blend 30 98 90 Festuca rubra var. commutata or Festuca rubra This turf seed mix in Table 4.3 is for dry situations where there is no need for much water. The advantage is that this mix requires very little maintenance. Table4.3 Low-Growing Turf Seed Mix % Wei~bt 0/o Purity % Germination Dwarf tall fescue (several varieties) 45 98 Festuca anmdinacea var. Dwarf perennial rye (Barclay) 30 98 Lolium perenne var. bare/av Redfescue 20 98 Festuca rubra Colonial beotgrass 5 98 Awostis tenuis Table 4.4 presents a mix recommended for bioswales and other intermittently wet areas. Table 4.4 Bioswale Seed Mix* 90 90 90 90 %Weight % Purity o/o Germination Tall or meadow fescue 75-80 98 90 Festuca arundinacea or Festuca elatior Seaside/Creeping bentgrass 10-15 92 85 Awostis pa/ustris Redtop bentgrass 5-10 90 80 Awostis alba or Awostis fti~anlea • Modified Briargreen, Jnc. Hydroseeding Guide Wetlands Seed Mix Volume /1-Construction Stormwater Pollution Prevention 4-17 Maintenance Standards 4-18 The seed mix shown in Table 4.5 is a recommended low-growing, relatively non-invasive seed mix appropriate for very wet areas that are not regulated wetlands. Other mixes may be appropriate, depending on the soil type and hydrology of the area. Recent research suggests that bentgrass (agrostis sp.) should be emphasized in wet-area seed mixes. Apply this mixture at a rate of 60 pounds per acre. Table 4.5 Wet Area Seed Mix* %Weight % Puritv % Germination Tall or meadow fescue 6()..70 98 90 Festuca arundinacea or Festuca elatior Seaside/Creeping bentgrass 10-15 98 85 Al!rostis valustris Meadow foxtail 10-15 90 80 Alepocuros pratensis Alsike clover 1-6 98 90 Trifolium hybridwn Redtop bentgrass 1-6 92 85 Awostis alba • Modified Briargreen, Inc. Hydroseeding Guide Wetlands Seed Mix The meadow seed mix in Table 4.6 is recommended for areas that will be maintained infrequently or not at all and where colonization by native plants is desirable. Likely applications include rural road and utility right- of-way. Seeding should take place in September or very early October in order to obtain adequate establishment prior to the winter months. The appropriateness of clover in the mix may need to be considered, as this can be a fairly invasive species. If the soil is amended, the addition of clover may not be necessary. Table 4.6 Meadow Seed Mix %Weieht % Puritv % Germination Redtop or Oregon bentgrass 20 92 85 Al!rostis alba or Al!rostis oref!onensis Redfescue 70 98 90 Festuca rubra White dutch clover 10 98 90 Tri{olium revens • Any seeded areas that fail to establish at least 80 percent cover (100 percent cover for areas that receive sheet or concentrated flows) shall be reseeded. If reseeding is ineffective, an alternate method, such as sodding, mulching, or nets/blankets, shall be used. If winter weather prevents adequate grass growth, this time limit may be relaxed at the discretion of the local authority when sensitive areas would otherwise be protected. Volume II -Construction Stormwater Pollution Prevention February 2005 B2l February 2005 After adequate cover is achieved, any areas that experience erosion shall be reseeded and protected by mulch. If the erosion problem is drainage related, the problem shall be fixed and the eroded area reseeded and protected by mulch. Seeded areas shall be supplied with adequate moisture, but not watered to the extent that it causes runoff. Volume II -Construction Stormwater Pollution Prevention 4-19 BMP C121: Mulching Purpose The purpose of mulching soils is to provide immediate temporary protection from erosion. Mulch also enhances plant establishment by conserving moisture, holding fertilizer, seed, and topsoil in place, and moderating soil temperatures. There is an enormous variety of mulches that can be used. Only the most common types are discussed in this section. Conditions of Use As a temporary cover measure, mulch should be used: Design and Installation Specifications Maintenance Standards 4-20 On disturbed areas that require cover measures for less than 30 days. As a cover for seed during the wet season and during the hot summer months. During the wet season on slopes steeper than 3H: 1 V with more than I 0 feet of vertical relief. Mulch may be applied at any time of the year and must be refreshed periodically. For mulch materials, application rates, and specifications, see Table 4.7. Note: Thicknesses may be increased for disturbed areas in or near sensitive _ar~as or other areas highly susceptible to erosion. Mulch used within the ordinary high-water mark of surface waters should be selected to minimize potential flotation of organic matter. Composted organic materials have higher specific gravities (densities) than straw, wood, or chipped material. The thickness of the cover must be maintained. Any areas that experience erosion shall be remulched and/or protected with a net or blanket. If the erosion problem is drainage related, then the problem shall be fixed and the eroded area remulched. Volume II -Construction Stormwater Pollution Prevention February 2005 Table 4.7 Mulch Standards and Guidelines Mulch Application Material Qualitv Standards Rates Remarks Straw Air-dried; free from 211 -3 11 thick; 5 Cost-effective protection when applied with adequate undesirable seed and bales per 1000 sf thickness. Hand-application generally requires greater coarse material. or 2-3 tons per thickness than blown straw. The thickness of straw may be acre reduced by halfwheo used in conjunction with seeding. In windy areas straw must be held in place by crimping, using a tackifier, or covering with netting. Blown straw always has to be held in place with a tackifier as even light winds will blow it away. Straw, however, has several deficiencies that should be considered when selecting mulch materials. It often introduces and/or encourages the propagation of weed species and it has no significant long-term benefits. Straw should be used only if mulches with long-term benefits are tmavailable locally. It should also not be used within the ordinary high-water elevation of surface waters ( due to flotation). Hydromulch No growth Approx. 25-30 Shall be applied with hydromulcher. Shall not be used inhibiting factors. lbs per 1000 sf without seed and tackifier unless the application rate is at or 1500 -2000 least doubled. Fibers longer than about %-1 inch clog lbs per acre hydromulch equipment. Fibers should be kept to less than% inch. Composted No visible water or 2" thick min.; More effective control can be obtained by increasing Mulch and dust during approx. 100 tons thickness to 3". Excellent mulch for protecting final grades Compost handling. Must be per acre (approx. until landscaping because it can be directly seeded or tilled purchased from 800 lbs per yard) into soil as an amendment. Composted mulch has a coarser supplier with Solid size gradation than compost. It is more stable and practical Waste Handling to use in wet areas and during rainy weather conditions. Permit (unless exempt). Chipped Site Average size shall 2"minimum This is a cost-effective way to dispose of debris from Vegetation be several inches. thickness clearing and grubbing, and it eliminates the problems Gradations from associated with bwning. Generally, it should not be used on fines to 6 inches in slopes above approx. 10% because of its tendency to be length for texture, transported by runoff. It is not recommended within 200 variation, and feet of surface waters. If seeding is expected shortly after interlocking mulch, the decomposition of the chipped vegetation may tie properties. up nutrients important to grass establishment. Wood-based No visible water or 2" thick; approx. This material is often called "hog or hogged fuel." It is Mulch dust during 100 tons per acre usable as a material for Stabilized Construction Entrances handling. Must be (approx. 800 lbs. (BMP CIOS) and as a mulch. The nse of mulch ultimately purchased from a per cubic yard) improves the organic matter in the soil. Special caution is supplier with a Solid advised regarding the source and composition of wood- Waste Handling based mulches. Its preparation typically does not provide Permit or one any weed seed contra~ so evidence of residual vegetation in exempt from solid its composition or known inclusion of weed plants or seeds waste regulations. should be monitored and prevented ( or minimized). February 2005 Volume II -Construction Stonnwater Pollution Prevention 4-21 BMP C124: Sodding Purpose Conditions of Use Design and Installation Specifications Maintenance Standards 4-28 The purpose of sodding is to establish permanent turf for immediate erosion protection and to stabilize drainage ways where concentrated overland flow will occur. Sodding may be used in the following areas: • Disturbed areas that require short-term or long-term cover. Disturbed areas that require immediate vegetative cover. All waterways that require vegetative lining. Waterways may also be seeded rather than sodded, and protected with a net or blanket. Sod shall be free of weeds, of uniform thickness (approximately I-inch thick), and shall have a dense root mat for mechanical strength. The following steps are recommended for sod installation: Shape and smooth the surface to final grade in accordance with the approved grading plan. The swale needs to be overexcavated 4 to 6 inches below design elevation to allow room for placing soil amendment and sod. Amend 4 inches (minimum) of compost into the top 8 inches of the soil if the organic content of the soil is less than ten percent or the permeability is less than 0.6 inches per hour. Compost used should meet Ecology publication 94-038 specifications for Grade A quality compost. Fertilize according to the supplier's reconunendations. Work lime and fertilizer 1 to 2 inches into the soil, and smooth the surface. Lay strips of sod beginning at the lowest area to be sodded and perpendicular to the direction of water flow. Wedge strips securely into place. Square the ends of each strip to provide for a close, tight fit. Stagger joints at least 12 inches. Staple on slopes steeper than 3H:1V. Staple the upstream edge of each sod strip. Roll the sodded area and irrigate. When sodding is carried out in alternating strips or other patterns, seed the areas between the sod immediately after sodding. If the grass is unhealthy, the cause shall be determined and appropriate action taken to reestablish a healthy groundcover. Ifit is impossible to establish a healthy groundcover due to frequent saturation, instability, or some other cause, the sod shall be removed, the area seeded with an appropriate mix, and protected with a net or blanket. Volume If -Construction Stormwater Pollution Prevention February 2005 BMP C125: Topsoiling Purpose Conditions of Use Design and Installation Specifications February 2005 To provide a suitable growth medium for final site stabilization with vegetation. While not a permanent cover practice in itself, topsoiling is an integral component of providing permanent cover in those areas where there is an unsuitable soil surface for plant growth. Native soils and disturbed soils that have been organically amended not only retain much more stormwater, but they also serve as effective biofilters for urban pollutants and, by supporting more vigorous plant growth, reduce the water, fertilizer and pesticides needed to support installed landscapes. Topsoil does not include any subsoils but only the material from the top several inches including organic debris. Native soils should be left undisturbed to the maximum extent practicable. Native soils disturbed during clearing and grading should be restored, to the rnaximwn extent practicable, to a condition where moisture-holding capacity is equal to or better than the original site conditions. This criterion can be met by using on-site native topsoil, incorporating amendments into on-site soil, or importing blended topsoil. Topsoiling is a required procedure when establishing vegetation on shallow soils, and soils of critically low pH (high acid) levels. Stripping of existing, properly functioning soil system and vegetation for the purpose of topsoiling during construction is not acceptable. If an existing soil system is functioning properly it shall be preserved in its undisturbed and uncompacted condition. Depending on where the topsoil comes from, or what vegetation was on site before disturbance, invasive plant seeds may be included and could cause problems for establishing native plants, landscaped areas, or grasses. Topsoil from the site will contain mycorrhizal bacteria that are necessary for healthy root growth and nutrient transfer. These native mycorrhiza are acclimated to the site and will provide optimwn conditions for establishing grasses. Commercially available mycorrhiza products should be used when topsoil is brought in from off-site. If topsoiling is to be done, the following items should be considered: Maximize the depth of the topsoil wherever possible to provide the maximum possible infiltration capacity and beneficial growth medium. Topsoil depth shall be at least 8 inches with a minimwn organic content of 10 percent dry weight and pH between 6.0 and 8.0 or matching the pH of the undisturbed soil. This can be accomplished either by returning native topsoil to the site and/or incorporating organic amendments. Organic amendments should be incorporated to a minimum 8-inch depth except where tree roots or other natural Volume II -Construction Stormwater Pollution Prevention 4-29 4-30 features limit the depth of incorporation. Subsoils below the 12-inch depth should be scarified at least 2 inches to avoid stratified layers, where feasible. The decision to either layer topsoil over a subgrade or incorporate topsoil into the underlying layer may vary depending on the planting specified. If blended topsoil is imported, then fines should be limited to 25 percent passing through a 200 sieve. The final composition and construction of the soil system will result in a natural selection or favoring of certain plant species over time. For example, recent practices have shown that incorporation of topsoil may favor grasses, while layering with mildly acidic, high-carbon amendments may favor more woody vegetation. Locate the topsoil stockpile so that it meets specifications and does not interfere with work on the site. It may be possible to locate more than one pile in proximity to areas where topsoil will be used. Allow sufficient time in scheduling for topsoil to be spread prior to seeding, sodding, or planting. Care must be taken not to apply to subsoil if the two soils have contrasting textures. Sandy topsoil over clayey subsoil is a particularly poor combination, as water creeps along the junction between the soil layers and causes the topsoil to slough. If topsoil and subsoil are not properly bonded, water will not infiltrate the soil profile evenly and it will be difficult to establish vegetation. The best method to prevent a lack of bonding is to actually work the topsoil into the layer below for a depth of at least 6 inches. Ripping or re-structuring the subgrade may also provide additional benefits regarding the overall infiltration and interflow dynamics of the soil system. Field exploration of the site shall be made to determine if there is surface soil of sufficient quantity and quality to justify stripping. Topsoil shall be friable and loamy (loam, sandy loam, silt loam, sandy clay loam, clay loam). Areas of natural ground water recharge should be avoided. Stripping shall be confined to the immediate construction area. A 4-to 6-inch stripping depth is common, but depth may vary depending on the particular soil. All surface runoff control structures shall be in place prior to stripping. Stockpiling of topsoil shall occur in the following manner: Side slopes of the stockpile shall not exceed 2: 1. An interceptor dike with gravel outlet and silt fence shall surround all topsoil stockpiles between October I and April 30. Between May 1 Volume II -Construction Stormwater Pollution Prevention February 2005 Maintenance Standards February 2005 and September 30, an interceptor dike with gravel outlet and silt fence shall be installed if the stockpile will remain in place for a longer period of time than active construction grading. Erosion control seeding or covering with clear plastic or other mulching materials of stockpiles shall be completed within 2 days (October I through April 30) or 7 days (May 1 through September 30) of the formation of the stockpile. Native topsoil stockpiles shall not be covered with plastic. Topsoil shall not be placed while in a frozen or muddy condition, when the subgrade is excessively wet, or when conditions exist that may otherwise be detrimental to proper grading or proposed sodding or seeding. Previously established grades on the areas to be topsoiled shall be maintained according to the approved plan. When native topsoil is to be stockpiled and reused the following should apply to ensure that the mycorrhizal bacterial, earthworms, and other beneficial organisms will not be destroyed: I. Topsoil is to be re-installed within 4 to 6 weeks; 2. Topsoil is not to become saturated with water; 3. Plastic cover is not allowed. • Inspect stockpiles regularly, especially after large storm events. Stabilize any areas that have eroded. Volume II -Construction Stonnwater Pollution Prevention 4-31 BMP C151: Concrete Handling Purpose Concrete work can generate process water and slurry that contain fine particles and high pH, both of which can violate water quality standards in the receiving water. This BMP is intended to minimize and eliminate concrete process water and slurry from entering waters of the state. Conditions of Use Any time concrete is used, these management practices shall be utilized. Design and Installation Specifications Maintenance Standards February 2005 Concrete construction projects include, but are not limited to, the following: Curbs Sidewalks Roads Bridges Foundations Floors Runways Concrete truck chutes, pumps, and internals shall be washed out only into formed areas awaiting installation of concrete or asphalt. Unused concrete remaining in the truck and pump shall be returned to the originating batch plant for recycling. Hand tools including, but not limited to, screeds, shovels, rakes, floats, and trowels shall be washed off only into formed areas awaiting installation of concrete or asphalt. Equipment that cannot be easily moved, such as concrete pavers, shall only be washed in areas that do not directly drain to natural or constructed stormwater conveyances. Washdown from areas such as concrete aggregate driveways shall not drain directly to natural or constructed stormwater conveyances. When no formed areas are available, washwater and leftover product shall be contained in a lined container. Contained concrete shall be disposed of in a manner that does not violate groundwater or surface water quality standards. Containers shall be checked for holes in the liner daily during concrete pours and repaired the same day. Volume II -Construction Stormwater Pollution Prevention 4-43 BMP C180: Small Project Construction Stormwater Pollution Prevention Purpose Conditions of Use Design and Installation Specifications February 2005 To prevent the discharge of sediment and other pollutants to the maximum extent practicable from small construction projects. On small construction projects, those adding or replacing less than 2,000 square feet of impervious surface or clearing less than 7,000 square feet. Plan and implement proper clearing and grading of the site. It is most important only to clear the areas needed, thus keeping exposed areas to a minimum. Phase clearing so that only those areas that are actively being worked are uncovered. Note: Clearing limits should be flagged in the lot or area prior to initiating clearing. Soil shall be managed in a manner that does not permanently compact or deteriorate the final soil and landscape system. If disturbance and/or compaction occur the impact must be corrected at the end of the construction activity. This shall include restoration of soil depth, soil quality, permeability, and percent organic matter. Construction practices must not cause damage to or compromise the design of permanent landscape or infiltration areas. Locate excavated basement soil a reasonable distance behind the curb, such as in the backyard or side yard area. This will increase the distance eroded soil must travel to reach the storm sewer system. Soil piles should be covered until the soil is either used or removed. Piles should be situated so that sediment does not run into the street or adjoining yards. Backfill basement walls as soon as possible and rough grade the lot. This will eliminate large soil mounds, which are highly erodible, and prepares the lot for temporary cover, which will further reduce erosion potential. Remove excess soil from the site as soon as possible after backfilling. This will eliminate any sediment loss from surplus fill. If a lot has a soil bank higher than the curb, a trench or berm should be installed moving the bank several feet behind the curb. This will reduce the occurrence of gully and rill erosion while providing a storage and settling area for stormwater. The construction entrance should be stabilized where traffic will be leaving the construction site and traveling on paved roads or other paved areas within 1,000 feet of the site. Volume II -Construction Stormwater Pollution Prevention 4-55 4-56 Provide for periodic street cleaning to remove any sediment that may have been tracked out. Sediment should be removed by shoveling or sweeping and carefully removed to a suitable disposal area where it will not be re-eroded. Utility trenches that run up and down slopes must be backfilled within seven days. Cross-slope trenches may remain open throughout construction to provide runoff interception and sediment trapping, provided that they do not convey turbid runoff off site. Volume II -Construction Stormwater Pollution Prevention February 2005 l'5 3 /, APPENDIX "C" OPERATION AND MAINTENANCE MANUAL LARSON & ASSOCIATES, INC. SURVEYORS, ENGINEERS AND PLANNERS 9027 PACIFIC A VENUE, SUITE 4 TACOMA, WA 98444 (253) 474-3404 (_ I RESPONSIBLE PARTY FOR THE MAINTENANCE OF THE PRIVATE STORM DRAINAGE SYSTEM UNTIL THE HOMEOWNERS ASSOCIATION BECOMES IN EFFECT: JKMONARCH CONT ACT: ROY SIMMONS P.O. BOX 188 PUYALLUP, WA. 98371 (253) 840-5660 ESTIMATED ANNUAL COST OF MAINTENANCE OF THE STORM DRAINAGE SYSTEM AS IDENTIFIED IN ATTACHMENT "A" IS $100 PER YEAR. NOTE: THIS OPERATION AND MAINTENANCE MANUAL SHALL BE KEPT AT THE PROJECT SITE AT ALL TIMES AND SHALL BE MADE AVAILABLE TO THE CITY OF DES MOINES FOR INSPECTION UPON REQUEST. {_ 2 Description of Lund Short Plat II Stormwater System. Stom1water infiltration is not feasible on this site due to the soils as depicted in the geotech results provided by Krazan (see Appendix A). Full lot dispersion of roof runoff is also not possible because of the size and layout of these lots. Flow control and water quality will therefore be mitigated utilizing the "Basic Dispersion" and "Restricted Footprint Credit" BMP's as outlined in Figure C.1.3.A, Flowchart for Determining Application of Flow Control BMP's (See Appendix A). Each driveway will utilize Basic Dispersion by being graded so as to direct surface runoff to a 2' wide by 0.5' deep gravel transition strip. The runoff will then disperse over a IO' wide vegetated flow path. In order to utilize the "Restricted Footprint Credit", the houses will be constructed with areas of approximately I. 768 SF and 1404 SF. The maximum impervious area for this RS zone is 3,428 SF (65% oflot size). We therefore can utilize splash blocks to release some of the roof runoff to the yards. The rest of the roof runoff will be conveyed to the downspout tightline and then directed to the existing 4" perforated stub out connection located in Lot "A" before entering the catch basin located in SE l 62"d Street to the northwest of our site. The catch basin was originally installed to collect runoff from the first Lund Short Plat. Since we will only be conveying runoff from approximately 980 SF to it, the existing system will easily accommodate it. See attached drainage and erosion control plans for more information. ATTACHMENT "A" CY Inspection Period: Number of Sheets Attached: Date Inspected: Name of Inspector: ATTACHMENT "A" MAINTENANCE PROGRAM Inspector's Signature: ___________________ _ c_s INSTRUCTIONS FOR USE OF MAINTENANCE CHECKLISTS The following pages contain maintenance needs for most of the components that are part of your drainage system, as well as for some components that you may not have. Let the City know if there are any components that are missing from these pages. Ignore the requirements that do not apply to your system. You should plan to complete a checklist for all system components on the following schedule: (1) Monthly from November through April (2) Once in late summer (preferable September) (3) After any major storm (use 1-inch in 24 hours as a guideline), items marked "S"only. Using photocopies of these pages, check off the problems you looked for each time you did an inspection. Add comments on problems found and actions taken. Keep these "checked" sheets in your files, as they will be used to write your annual report. Some items do not need to be looked at every lime an inspection is done. Use the suggested frequency at the left of each item as a guideline for your inspection. Cb APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES NO. 6 -CONVEYANCE PIPES AND DITCHES Maintenance Component Pipes Ditches Defect or Problem Sediment & debris accumulation Conditions When Maintenance is Needed Accumulated sediment or debris that exceeds 20% of the diameter of the pipe. Results Expected When Maintenance is Performed Water flows freely through pipes. Vegetation/roots Vegetation/roots that reduce free movement of Water flows freely through pipes. water through pipes. Contaminants and Any evidence of contaminants or pollution such Materials removed and disposed of pollution as oil, gasoline, concrete slurries or paint. according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Damage to protective Protective coating is damaged; rust or corrosion Pipe repaired or replaced. coating or corrosion is weakening the structural integrity of any part of pipe. Damaged Any dent that decreases the cross section area of Pipe repaired or replaced. pipe by more than 20% or is determined to have Trash and debris Sediment accumulation Noxious weeds Contaminants and pollution Vegetation Erosion damage to slopes Rock lining out of place or missing (If Applicable) weakened structural integrity of the pipe. Trash and debris exceeds 1 cubic foot per 1,000 Trash and debris cleared from square feet of ditch and slopes. ditches. Accumulated sediment that exceeds 20% of the design depth. Any noxious or nuisance vegetation which may constitute a hazard to County personnel or the public. Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Vegetation that reduces free movement of water through ditches. Any erosion observed on a ditch slope. One layer or less of rock exists above native soil area 5 square feel or more, any exposed native sail. Ditch cleaned/flushed of all sediment and debris so that it matches design. Noxious and nuisance vegetation removed according to applicable regulations. No danger of noxious vegetation where County personnel or the public might normally be. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Water flows freely through ditches. Slopes are not eroding. Replace rocks to design standards. 2009 Surface Water Design Manual -Appendix A I/912009 A-lI C7 APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ F ACJLITIES NO. 8 -ENERGY DISSIPATERS Maintenance Defect or Problem Conditions When Maintenance Is Needed Resu Its Expected When Component Maintenance is Performed. Site Trash and debris Trash and/or debris accumulation. Dissipater clear of trash and/or debris. Contaminants and Any evidence of contaminants or pollution such Materials removed and disposed of pollution as oil, gasoline, concrete slurries or paint. according to applicable regulations. Source control BMPs Implemented if appropriate. No contaminants present other than a surface oil film. Rock Pad Missing or moved Only one layer of rock exists above native soil in Rock pad prevents erosion. Rock area five square feet or larger or any exposure of native soil. Dispersion Trench Pipe plugged with Accumulated sediment that exceeds 20% of the Pipe cleaned/flushed so that it sediment design depth. matches design. Not discharging water Visual evidence of water discharging at Water discharges from feature by properly concentrated points along trench (normal sheet flow. condition Is a "sheet flow" of water along trench). Perforations plugged. Over 1/4 of perforations in pipe are plugged with Perforations freely discharge flow. debris or sediment. Water flows out top of Water flows out of distributor catch basin during No flow discharges from distributor udistributorn catch any storm less than the design storm. catch basin. basin. Receiving area over~ Water in receiving area is causing or has No danger of landslides. saturated potential of causing landslide problems. Gabions Damaged mesh Mesh of gabion broken, twisted or deformed so Mesh is intact, no rock missing. structure is weakened or rock may fall out. Corrosion Gabion mesh shows corrosion through more than All gabion mesh capable of Y. of its gage. containing rock and retaining designed form. Collapsed or Gabion basket shape deformed due to any All gabion baskets intact, structure deformed baskets cause. stands as designed. Missing rock Any rock missing that could cause gabion to No rock missing. loose structural integrity. Manhole/Chamber Worn or damaged Structure dissipating flow deteriorates to Xi or Structure is in no danger of failing. post, baffles or side of original size or any concentrated worn spot chamber exceeding one square foot which would make structure unsound. Damage to wall, Cracks wider than %-inch or any evidence of soil Manhole/chamber is sealed and frame, bottom, and/or entering the structure through cracks, or structurally sound. top slab maintenance inspection personnel determines that the structure is not structurally sound. Damaged pipe joints Cracks wider than %-inch at the joint of the No soil or water enters and no water inleUoutlet pipes or any evidence of soil entering discharges at the joint of inlet/outlet the structure at the joint of the inlet/outlet pipes. pipes. 2009 Surface Water Design Manual -Appendix A CB 1/9/2009 APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ F ACIL!TIES NO. 9 -FENCING Maintenance Defect or Problem Conditions When Maintenance is Needed Results Expected When Maintenance Is Performed Component Site Erosion or holes under fence Erosion or holes more than 4 inches high and 12-No access under the fence. 18 inches wide permitting access through an opening under a fence. Wood Posts, Boards Missing or damaged Missing or broken boards, post out of plumb by No gaps on fence due to missing or and Cross Members parts more than 6 inches or cross members broken broken boards, post plumb to within 1 % inches, cross members sound. Metal Posts, Rails and Fabric 1/912009 Weakened by rotting Any part showing structural deterioration due to or insects rotting or insect damage Damaged or failed Concrete or metal attachments deteriorated or post foundation unable to support posts. Damaged parts Post out of plumb more than 6 inches. Top rails bent more than 6 inches. All parts of fence are structurally sound. Post foundation capable of supporting posts even in strong wind. Post plumb to within 11-4 inches. Top rail free of bends greater than 1 inch. Any part of fence (including post, top rails, and Fence is aligned and meets design fabric) more than 1 foot out of design alignment. standards. Missing or loose tension wire. Tension wire in place and holding fabric. Deteriorated paint or Part or parts that have a rusting or scaling protective coating condition that has affected structural adequacy. Openings in fabric Openings in fabric are such that an B~inch diameter ball could fit through. Structurally adequate posts or parts with a unifonn protective coating. Fabric mesh openings within 50% of grid size. 2009 Surface Water Design Manual -Appendix A A-14 APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES NO. 11 -GROUNDS (LANDSCAPING) Maintenance Defect or Problem Conditions When Maintenance is Needed Results Expected When Component Maintenance is Performed Site Trash or litter Any trash and debris which exceed 1 cubic foot Trash and debris cleared from site. per 1,000 square feet (this is about equal to the amount of trash it would take to fill up one standard size office garbage can). In general, there should be no visual evidence of dumping. Noxious weeds Any noxious or nuisance vegetation which may Noxious and nuisance vegetation constitute a hazard to County personnel or the removed according to applicable public. regulations. No danger of noxious vegetation where County personnel or the public might normally be. Contaminants and Any evidence of contaminants or pollution such Materials removed and disposed of pollution as oil, gasoline, concrete slurries or paint. according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Grass/groundcover Grass or groundcover exceeds 18 inches in Grass or groundcover mowed to a height. height no greater than 6 inches. Trees and Shrubs Hazard Any tree or limb of a tree identified as having a No hazard trees in facility. potential to fall and cause property damage or U,reaten human life. A hazard tree identified by a qualified arborist must be removed as soon as possible. Damaged Limbs or parts of trees or shrubs that are split or Trees and shrubs with less than 5% broken which affect more than 25% of the total of total foliage with split or broken foliage of the tree or shrub. limbs. Trees or shrubs that have been blown down or No blown down vegetation or knocked over. knocked over vegetation. Trees or shrubs free of injury. Trees or shrubs which are not adequately Tree or shrub in place and supported or are leaning over, causing exposure adequately supported; dead or of the roots. diseased trees removed. A-16 CID 2009 Surface Water Design Manual -Appendix A 1/9/2009 ATTACHMENT "B" Cl I INSTRUCTIONS FOR THE OWNER/SIN Lund Short Plat II POLLUTION SOURCE CONTROLS The attached material includes information on pollution source controls. Pollution source controls are actions taken by a person or person representing a business to reduce the amount of pollution reaching surface and ground waters. Pollution source controls also called "best management practices" (BMP's) include: Altering the activity (e.g., substitute not-toxic products or recycle) Enclosing or covering the activity. Segregating the activity (e.g. diverting surface water runoff away from an area that is contaminated.) Pollution source controls are needed because of the contamination found in surface water runoff from commercial areas and the effect of this contamination on aquatic Ii fe and human health. Research on urban runoff in the Puget Sound area and elsewhere has found oil and grease, nutrients, organic substances, toxic metals, bacteria, viruses, and sediments at unacceptable levels. Effects of contaminate runoff include closure of shellfish harvesting areas and swimming areas, pollution of wells, mortality of young fish and other aquatic organisms, tumors on fish, and impairment of fish reproduction. Lund Short Plat II project contains impervious surfaces that will collect contaminates from automobiles, garbage, and improperly disposed of chemicals. These materials are conveyed to the storm drainage systems and will enter into the ground water, if not treated properly. Attachment "B" contains a number of BMP's for various uses within the development site. Each o\'.11er shall give a copy of the BMP's suitable to this or her respective activity. If a certain activity is not contained in Attachment "B", please contact Larson and Associates at 253-474- 3404 for a speci lie BMP activity type. REQUIRED ACTIONS OF ALL OWNERS The following actions shall be taken by all owners to ensure that pollution generated on Lund Short Plat II project is minimized. I) Warning signs (e.g. "Dump no waste -drains to Stream") shall be stenciled or embossed adjacent to all catch basin inlets. They shall be repainted once a year or more as necessary. 2) Paved roadways shall be swept twice a year. It is recommended that newer high-velocity vacuum sweeper be used. 3) The storm drainage system shall be maintained per Attachment "A" 4) No activities shall be conducted on the property that is likely to result in a short-term high concentration discharge of pollution to the storm system. Such activities shall include, but are not limited to car washes, vehicle maintenance, and cleaning of equipment and or vehicles, unless the project has been properly permitted for such uses and the BMP' s for such uses have been received by the owner. 5) Automobile fluids, chemicals etc. shall be disposed oflegally and properly. 6) All garbage shall be contained in appropriate containers. 4.3 BMPs TO CONSIDER FOR ALL ACTIVITIES This is a summary of items that each business/homeowner should consider. As stated before, most of these are common sense, housekeeping types of solutions, but if each business/homeowner would take some action on each of these, the improvement in water quality would be substantial. 1. Avoid the activity or reduce its occurrence If you can, avoid the activity or do it less frequently. If there a substitute process or a different material you can use to get the job done? Can you do a larger run of a process at one time, thus reducing the number of times per week or month it needs to be repeated? For instance, raw materials could be delivered close to the time of use instead of being stockpiled and exposed to the weather. Perhaps you could avoid one solvent-washing step altogether. The Department of Ecology or the Tacoma-Pierce County Health Department can provide pollution prevention assistance. 2. Move the activity indoors Sometimes it is fairly easy to move an activity indoors out of the weather. The benefits of this are twofold; you prevent runoff contamination, and you provide for easier, more controlled cleanup if a spill occurs. An example would be unloading and storing barrels of chemicals inside a garage area instead of doing it outside. Please be aware that moving storage areas indoors may require installation of fire suppression equipment or other building modifications as required by the Uniform Building Code, the Uniform Fire Code, or local ordinances. 3. Use less material Don't buy or use more material than you really need. This not only helps keep potential disposal, storage and pollution problems to a minimum, but will probably save you money, too. 4. Use the least toxic materials available Investigate the use of materials that are Jess toxic than what you use now. Perhaps a caustic-type detergent or a solvent could be replaced with a more environmentally friendly product. Such a change might allow you to discharge process water to the sanitary sewer instead of paying for expensive disposal ( contact City of Tacoma to find out about allowable sanitary discharges and pretreatment permits). Remember that even if you do switch to a biodegradable product, nothing but uncontaminated water is allowed to enter the storm drain system. 5. Create and maintain vegetated areas near activity locations Vegetation of various kinds can help filter pollutants out of stormwater, so it is advisable to route stormwater through vegetated areas located near your activity. For instance, many parking Jots contain grassy islands, typically formed in a "hump". By creating those islands as depressions instead of humps, they can be used to treat runoff from the parking Jot or roof. Also, don't forget the erosion control benefits of vegetation at your site. l \L\ 6. Locate activities as far as possible from surface drainage paths Activities located as far as possible from known drainage paths, ditches, streams, and drains will be less likely to pollute, since it will take longer for material to reach the drainage feature. This gives you more time to react in the event of a spill, or if it is a "housekeeping" issue may protect the local waters long enough for you to clean up the area around the activity. Don't forget that groundwater issues are always prominent, no matter where the activity is located so the actions taken on your site on a day-to-day basis are always important, even in dry weather. 7. Keep storm drain systems clean Pollutants can concentrate over time in storm drainage structures such as catch basins, ditches and storm drains. When a large storm event occurs, it can mobilize these pollutants and carry them to receiving waters. Develop and implement maintenance practices, inspections, and schedules for treatment devices ( e.g., detention ponds, oil/water separators, vegetated swales, etc.). Requirements for cleaning catch basins will be discussed later in the specific BMP S.9. 8. Reduce, reuse and recycle as much as possible Always look for ways to recycle instead of just disposing. This can save money as well as keep both hazardous and non-hazardous materials out of the landfills. You can learn more about other businesses that have made process changes allowing recycling of chemicals by calling the DOE at 1-800-RECYCLE and requesting publication #9245 and 90-22. Another unique recycling opportunity for businesses is available through the "matchmaker", helping one company's waste become another company's asset. For instance, waste peach pits from a cannery become potpourri ingredients to another's business. Call IMEX at 206-625-623 to list your potentially usable solid or chemical waste in their publication. 9. Be an advocate for stormwater pollution prevention Help friends, partners and business associates find ways to reduce stormwater pollution in their activities. Most people want clean water, and do not pollute intentionally. Share your ideas and the BMPs in this manual to get them thinking about how their everyday activities affect water quality. 10. Report Violators Allowing anyone to pollute our waters is wrong. We all must do our part to protect water, fish, wildlife and our own health, by employing proper BMPs, and reporting those who are causing pollution. In Pierce County, call Pretreatment Inspections at 565-3013 to report dumping to sewers and Surface Water Management at 798-2725 to report incidents involving storm drains or ditches. LIS 11-5.10 STORMWATER MANAGEMENT MANUAL FOR THE PUGET SOUND BASIN BMPS FOR SMALL PARCELS A Small Parcel Stormwater Management Plan must be developed which satisfies the Small Parcel Minimum Requirements found in Volume II, Chapter II-2. These in tum may be satisfied by employing a suitable selection from the following list ofBMPs. BMP ES.10 PLANNED CLEARING AND GRADING Plan and implementation proper clearing and grading of the site. It is most important only to clear the areas needed, thus keeping exposed areas to a minimum. Phase clearing so that only those areas that are actively being worked are uncovered. Note: Clearing limits should be flagged in the lot or area prior to initiating clearing. BMP ES.20 EXCAVATING BASEMENT SOIL Located excavated basement soil a reasonable distance behind the curb, such as in the backyard or side yard area. This will increase the distance eroded soil must travel to reach the storm sewer system. Soil piles should be covered until the soil is either used or removed. Piles should be situated so that sediment does not run into the street or adjoining yards. BMP ES.30 BACKFILLING Backfill basement walls as soon as possible and rough grade the lot. This will eliminate large soil mounds which are highly erodible and prepares the lot for temporary cover which will further reduce erosion potential. BMP ES.40 REMOVAL OF EXCESS SOIL Remove excess soil from the site as soon as possible after backfilling. This will eliminate any sediment loss from surplus fill. BMP ES.50 MANAGEMENT OF SOIL BANKS If a lot has a soil bank higher than the curb, a trench or berm should be installed moving the bank several feet behind the curb. This will reduce the occurrence of gully and hill erosion while providing a storage and settling area for stormwater. BMP ES.60 CONSTRUCTION ROAD ACCESS Apply gravel or crushed rock to the driveway area and restrict truck traffic to this one route. Driveway paving can be installed directly over the gravel. This measure will eliminate soil from adhering to tires and stops soil from washing into the street. This measure requires periodic inspection and maintenance including washing, top-dressing with additional stone, reworking and compaction. (For further details see BMP E2.IO, Chapter II-5.7.1). C 117 BMP ES.70 SOIL STABILIZATION Stabilized denuded areas of the site by mulching, seeding, planting, or sodding. For further details on standards and specifications, see BMPs No. El .I 0, El.15, El .35, El .40 in Chapter II-5. BMP ES.80 STREET CLEANING Provide for periodic street cleaning to remove any sediment that may have been tracked out. Sediment should be removed by shoveling or sweeping and carefully removed to a suitable disposal area where it will not be re-eroded. 11-5.11 References (1) Goldman, Steven J., Erosion and Sediment Control Handbook, McGraw-Hill, 1986. (2) Homer, Richard R., Juno Guedry and Michael H. Kortenhof, Highway Construction Site Erosion and Pollution Control Manual, Washington State Department of Transportation with the United States Department of Transportation Federal Highway Administration, WA-RD 200.2, January, 1990. (3) Metro, Summary of Preliminary Data Analysis -BMP Survey of Single Family Residential Construction Sites, January, 1984. ( 4) Brandy, Nile C., The Nature and Properties of Soils, Eight Edition, MacMillan, 1974. C. \l BEST MANAGEMENT PRACTICES FOR SINGLE-FAMILY RESIDENCES The actions we take each day in and around cur homes have a profound effect on stormwater quality in this region. Small amounts of pollution from many different sources can significantly affect our waterways. Yard maintenance, waste storage, car washing and maintenance, and pool cleaning are some of the activities that can adversely impact water quality. The best management practices (BMPS) discussed in this section are practical ways to keep stormwater from becoming polluted in the first place. It is recommended that all residences in Pierce County use these BMPS. Please note that some of these procedures are required by various state, federal, or county laws, and are noted as required BMPS. 3.1 AUTOMOBILE WASHING Most residents wash their cars in the driveway or on the street. Washwaters typically flow to a storm drain or ditch, which discharges stormwater directly to the nearest stream, lake or to Puget Sound. Soaps and detergents, even the biodegradable ones, can have immediate and long-term effects on critters living in waterbodies. The grime washed off the car also contains a variety of pollutants that can harm fish and wildlife. Suggested BMPs • Wash your car directly over your lawn or make sure the wash water drains to a vegetated area. This allows the water and soap to soak into the ground instead of running off into a local waterbody. • Ideally. no soaps or detergents should be used, but if you do use one, select one without phosphates. • Sweep driveways-and street gutters before washing vehicle to clean up dirt, leaves, trash and other materials that may flow to the storm drain along with your wash water. This helps reduce storm drain maintenance costs as well as protect water quality. • Commercial products are available that allow you to clean a vehicle without water. These were developed for areas where water is scarce, so a water saving benefit is realized as well as reduced pollution. • Use a nozzle on your hose to save water. • Do not wash your car if rain is expected. • Consider not washing your car at home. Take it to a commercial car wash that has a recycle system and discharges wastewater to the sanitary sewer for treatment. 3.2 AUTOMOBILE MAINTENANCE Many ofus are "weekend mechanics". We enjoy the cost savings of changing our own oil and antifreeze, topping off the battery with water, and generally making our car ' perform its best. There are many potentials for stormwater pollution associated with these activities, however, the following BMPs will - help you minimize pollution while servicing your car. Required BMPs • Recycle all oils, antifreeze. solvents and batteries. Many local car parts dealers and gas stations accept used oil. The Household Hazardous Waste facility at the Tacoma Landfill accepts oil, oil filters, antifreeze and solvents from both City of Tacoma and non-city residents. Pierce County and Tacoma also hold Household Hazardous Waste Turn-In days which will accept car wastes including old batteries. Old batteries can actually be worth money. Call shops listed under Batteries in the Yell ow Pages of the phone book to find out if they are paying for used batteries. Use the numbers listed in Chapter 7 to call for more information. C. I 8 • Never dump new or used automotive fluids or solvents on the ground, in a storm drain or street gutter, or in a waterbody. Eventually, it will make its way to local surface waters or groundwater, including the water we drink. • Do not mix wastes. The chlorinated solvents in some carburetor cleaners can contaminate a huge tank of used oil, rendering it unsuitable for recycling. Always keep your wastes in separate containers which are properly labeled and store them ont of the weather. Suggested BMPs • To dispose of oil filters, punch a hole in the top and let drain for 24 hours. This is where a large funnel in the top of your oil storage container will come in handy. After draining, wrap in 2 layers of plastic and dispose of in your regular garbage or recycle by taking it to the Tacoma Landfill Household Hazardous Waste facility (for Tacoma residents and non-residents). Pending State law may make disposal in your home garbage illegal, so please call the Hazardous Waste line at 1-800- 287-6429 for up-to-date information. • Use care in draining and collecting antifreeze to prevent accidental spills. Spilled antifreeze can be deadly to cats and dogs that ingest it. • Perform your service activities on concrete or asphalt or over a plastic tarp to make spill clean-up easier. Keep a bag of kitty litter on hand to absorb spills. Sprinkle a good layer on the spill, let it absorb for a little while and ten sweep it up. Place the contaminated litter in a plastic bag,' tie it up, and dispose of it in your regular garbage. Take care not to leave kitty litter out in the rain; it will form a sticky goo that is hard to clean up. • If you are doing bodv work outside, be sure to use a tarp to catch material resulting from grinding, sanding and painting. Dispose of this waste by double bagging in plastic and placing in your garbage. 3.3 STORAGE OF SOLID WASTES AND FOOD WASTES Improper storage of food and solid waste at residences can lead not only to water pollution problems, but problems with neighborhood pets and vermin as well. Following the BMPs listed below can help keep your property a clean and healthy place to live. Suggested BMPs • All waste containers kept outside should have lids. • Leaking waste containers should be replaced. • Store waste containers under cover if possible, or on grassy areas. • Inspect the storage area regularly to pick up loose scraps of material and dispose of them properly. • Recycle as much as you can. Pierce County offers curbside recycling to a majority of residents. Also, look under "Recycling" in the phone book for firms which take other recyclables. • Purchase products which have the least amount of packaging materials. • Compost biodegradable materials such as grass clippings and vegetable scraps instead of throwing them away. Your flower beds will love the finished compost, and we won't fill up our landfills so quickly. Call Pierce County Solid Waste at (253) 798-2179 for more information on composting. See the section on Composting for BMPs relating to that activity. • A fun alternative to traditional composting is worm composting. You can let worms do all the work for you by keeping a small vermiculture box just outside your kitchen. For more information on getting started with worms, call the numbers listed above. 3.4 COMPOSTING Composting is an earth-friendly activity as long as some common sense rules outlined below are followed. If you choose to compost, the following BMPs should be utilized. (19 Suggested BMPs • Compost piles must be located on an unpaved area where runoff can soak into the ground or be filtered by grass and other vegetation. Compost piles should be located in an area of your yard not prone to water ponding during storms, and should be kept well away from wetlands, streams, lakes and other drainage paths. • Avoid gutting hazardous or non-decomposable waste in the pile. • Cover the compost pile for two reasons: I. To keep stormwater from washing nutrients 1nto waterways. 2. To keep excess water from cooling down the pile, which will slow down the rate of decomposition. • Build bins of wood, chicken wire or fencing material to contain compost so it can't be washed away. Call Pierce County Solid Waste at (253) 798-4050 to get free composter designs and materials lists. • Building a small earthen dike around your compost pile is an effective means of preventing nutrient- rich compost drainage from reaching stormwater paths. 3.5 YARD MAINTENANCE AND GARDENING This section deals with the normal yard maintenance activities we all perform at our homes. Overwatering, overfertilizing, improper herbicide application and improper disposal of trimmings and clippings can all contribute to serious water pollution problems. Following the BMPs listed below will help alleviate pollutant runoff. Required BMPs Follow the manufacturers directions exactly for mixing and applying herbicides, fungicides and insecticides, and use them sparingly. Never apply when it is windy or when rain is expected. Never apply over water, within 100 feet of a well-head, or adjacent to streams or other waterbodies. Triple- rinse empty containers, using the rinsate for mixing your next batch of spray, and then double-bag and dispose of the empty container in your regular garbage. Never dispose of grass clippings or other vegetation in or near storm drains, streams, lakes or Puget Sound. Suggested BMPs • Follow manufacturers directions when applying fertilizers. More is not better, either for your lawn or for local waterbodies. Never apply fertilizers over water or adjacent to ditches, streams or other water bodies. Remember that organic fertilizers have a slow release of nitrogen, and less potential to pollute than synthetic fertilizers. Save water and-prevent pollution problems by watering your lawn sensibly. Lawns and gardens typically need the equivalent of I" of rainfall per week. You can check on how you're doing by putting a wide mouth jar out where you're sprinkling, and measure the water with a small plastic ruler. Overwatering to the point of runoff can carry polluting nutrients to the nearest waterbody. • Consider planting a vegetated buffer zone adjacent to streams or other water bodies on your property. Call the Pierce County Conservation District for advice and assistance in developing a planting plan. The Stream Team at the Conservation District may even be able to help you plant it! • Make sure all fertilizers and pesticides are stored in a covered location. Rain can wash the labels off of bottles and convert 50 lbs. of fertilizer into either a solid lump or a river of nutrients. • Compost all yard clippings, or use them as mulch to save water and keep down weeds in your garden. See Composting section for more information. • Practice organic gardening and virtually eliminate the need to use pesticides and fertilizers. Contact Pierce County Cooperative Extension at (253) 798-7180 or the Ask-A-Master Gardener program at (253) 798-7170 for information and classes on -earth-friendly gardening. • Pull weeds instead of spraying and get some healthy exercise, too. If you must spray, use the least toxic formulations that will get the job done. The Master Gardener program listed above can help advise you on which spray to use. • Work fertilizers into the soil instead ofletting them lie on the ground surface exposed to the next rain storm. • Contact your local garbage hauler for curbside pickup and recycling of yard waste. 3.6 SWIMMING POOL AND SPA CLEANING AND MAINTENANCE Despite the fact that we immerse ourselves in it, the water from pools and spas is far from chemically clean. Nutrients, pH, and chlorine can adversely affect fish and wildlife in waterbodies. Following these BMPs will ensure the cleanliness of your pool and the environment. Required BMPs • Pool and spa water must be dechlorinated if it is to be emptied into a ditch, on the ground, or a lawn or to the storm drainage system. Contact your pool chemical supplier to obtain the neutralizing chemicals you will need. The rate of flow into the ditch or drainage system must be regulated so that it does not cause problems such as erosion, surcharging or flooding. You must obtain permission from Pierce County Surface Water Management at (253) 798-2725 prior to discharging into any county ditch or facility. Water discharged to the ground or a lawn must not cross property lines and must not produce runoff. If you live-in a sewered area, you must discharge pool water to the sanitary sewer. Contact the pre-treatment unit at (253) 798-3013 for permission prior to discharge. • If pool and spa water cannot be dechlorinated, it must be discharged to the sanitary sewer. Prior to draining, your local wastewater treatment plant must be notified to ensure they are aware of the volume of discharge and the potential effects of chlorine levels. A pool service company can help you determine the frequency of cleaning and backwash of filters. • Diatomaceous earth used in pool filters cannot be disposed of in surface waters, on the ground, into storm drainage systems or septic systems. Dry it out as much as possible, bag it in plastic, and dispose of at the landfill. Suggested BMPs • Hire a professional pool service company to collect all pool water for proper disposal. Make sure to ask them where they will dispose of it and the kind of permits they hold to do so. 3.7 HOUSEHOLD HAZARDOUS MATERIAL USE, STORAGE, AND DISPOSAL Once we really start looking around our houses, the amount of hazardous materials we have on site is a real eye-opener. Oil-based paints and stains, paint thinner, gasoline, charcoal starter fluid, cleaners, waxes, pesticides, fingernail polish remover, and wood preservatives are just a few that most ofus have around the house. When products such as these are dumped on the ground or in a storm drain, they can be washed directly to receiving waters where they can harm fish and wildlife. They can also infiltrate into the ground and contaminate drinking water supplies. The same problem can occur if they are disposed of with your regular garbage; the containers can leak at the landfill and contaminate groundwater. The same type of contamination can occur if hazardous products are poured down a sink or toilet into a septic system. Don't pour them down the drain if you're on municipal sewers, either. Many compounds will "pass [ ?,I through" the wastewater treatment plant without treatment and contaminate receiving waters, or they can hann the biological process used at the treatment plant, reducing overall treatment efficiency. With such a diversity of hazardous products present in all homes in Pierce County, a large potential for serious environmental hann-exists if improper methods of storage, usage and disposal are employed. Using the following BMPs will help keep these materials out of our soils, sediments and waters. Required BMPs Dispose of hazardous materials and their containers properly. Never dump products labeled as poisonous, corrosive, caustic, flammable, inflammable, volatile, explosive danger, warning, caution or dangerous outdoors, in a storm drain, or into sinks, toilets or drains. Call Tacoma Refuse Utility Household Hazardous Waste at (253) 798-5418 or the Hazardous Waste Line at 1-800287-6429 for information on disposal methods, collection events, and alternative products. Household hazardous wastes from City of Tacoma residents and nonresidents are accepted at the Tacoma Landfill. Suggested BMPs • Check containers containing hazardous materials frequently for signs of leakage. If a container is rusty and has the potential of leaking soon, pace it in a secondary container before the leak occurs and prevent a clean-up problem. • Store hazardous materials containers under cover and off the ground. Keep them out of the weather to avoid rusting, freezing, cracking, labels being washed off, etc. Hazardous materials should be stored out of the reach of children. Never transfer to or store these materials in food or beverage containers which could be misinterpreted by a child as something to eat or drink. • Keep appropriate spill cleanup materials on hand. Kitty litter is good for many oil-based spills. • Ground-cloths and drip pans must be used under any work outdoors which involves hazardous materials such as oil-based paints, stains, rust removers, , masonry cleaners, and others bearing label warnings as outlined above. • Latex paints are not a hazardous waste, but are not accepted in liquid form at the landfill. To dispose, leave uncovered in a protected place until dry, then place in the garbage. If you wish to dry waste paint quickly, just pour kitty litter in the can to absorb the paint. Once paint is dry, leave the lid off when you place it in the garbage so your garbage collector can see that it is no longer liquid. • Use less toxic products whenever possible. The Hazardous Waste Line at 1 (800) 287-6429, and the Washington Toxics Coalition at (206) 632-1545 have information detailing alternatives to toxic products. • If an activity involving the use of a hazardous material can be moved indoors out of the weather, then do so. Make sure you can provide proper ventilation, however. • Follow manufacturers' directions in the use of all materials. Over-application of yard chemicals, for instance, can result in the washing of these compounds into receiving waterbodies. Never apply pesticides when rain is expected. When hazardous materials are in use, place the container inside a tub or bucket to minimize spills. C2.:L