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HomeMy WebLinkAboutStorm Drainage Report - PLN General - 6/12/2008 wSRECEIVED Q� JUN 12 2008 WestSound Engineering, Inc. BELFAIR OFFICE STORM DRAINAGE REPORT FAIR HARBOR Jurges Enterprises 2020 Enetai Beach Rd. Bremerton, WA 98310 (360) 377-0274 NG B& wAso tc�y�2 y ` WESTBOUND ENGINEERING, Inc. 1050 217 SW WILKINS DRIVE o PORT ORCHARD, WA 98366 NAL Phone: (360) 876-3770/Fax: (360) 876-0439 EXPIRES 4/4/¢oO Project No: 805.4 May 23, 2008 Storm Drainage Report WestSound Engineering Fair Harbor Job #805.4 TABLE OF CONTENTS: Section Pate No. ProjectDescription: ..................................................................................................................... 3 Existing Site Drainage Conditions: ............................................................................................. 3 Developed Site Drainage Conditions: ......................................................................................... 3 Up-Stream Drainage Basin:......................................................................................................... 3 DownstreamAnalysis:.................................................................................................................4 SoilsReport: ................................................................................................................................4 GeotechnicalReport: ................................................................................................................... 4 HydrologicAnalysis: ................................................................................................................... 4 EastBasin.................................................................................................................................... 5 WestBasin................................................................................................................................... 6 WaterQuantity Mitigation:.......................................................................................................... 7 WaterQuality Mitigation:............................................................................................................ 7 ConveyanceSystem:.................................................................................................................... 8 Temporary Erosion& Sediment Control:.................................................................................... 8 Summary:..................................................................................................................................... 9 Figure Description Pate No. 1) Site Map&Vicinity Map 9 2) USGS Topo and Off Site Basin Map 10 Appendices: Appendix A "County Reference Documents" Soils Map A-1-3 Soil Groups A-4 Modified Curve Numbers A-5 Runoff Manning's Numbers A-6 Isopluvial Maps A-7-9 Appendix B "Hydrologic Analysis" Existing Basin Maps B-1-2 Developed Drainage Maps B-3-4 East Basin Modeling Reports B-5-11 West Basin Modeling Reports B-12-17 Appendix C "Conveyance Analysis" Conveyance Map C-1 Conveyance Manning's Capacity Calculations C-2-5 Sub-Basin Flow Reports C-6-11 2 Storm Drainage Report WestSound Engineering Fair Harbor Job #805.4 PROJECT DE,S(RIPTION@ This project proposes to provide the improvements necessary to construct 20 single family residences on the existing 19.27-ac of land owned by Jurges Enterprises. The features proposed will include the reconditioning existing gravel access roads and the creation of two storm water detention systems. 7.18-ac of this site will be disturbed during the construction of the infrastructure. EXISTING SIT . DRAINAGE CONDITIONS: The site is comprised of existing roads and brushy grassy lands. A significant ridge crosses through the property from the southeast to the northwest effectively separating the project into two hydraulically separate pieces. These two resulting basins will hence forth be referred to as the East and West basins. The slopes within each basin vary up to 15%with an isolated area in the northwest corner of the West basin where slopes as steep as 20%exist. Each basins developed runoff is collected by wetland areas which are present in both basins. The wetland area in the west basin also receives flows from an unnamed stream which flows on site from the south. The east basins wetland area is primarily contained on the adjacent parcel to the east but the associated wetland buffer does cover a significant portion of the lots located in the lower east corner. These features are shown on the associated Site Map,page 9. DEVELOPED SITE DRAINAGE CONDITIONS: The developed condition for the site will consist of 20 lots designated for single family residences, an additional lot which contains the wells and water supply for the development and two more lots which provide for the 20 approved individual septic fields that will be required to support the proposed building sites. Two separate storm detention ponds, one for each basin, are also proposed for this site. The developed condition will also consist of various portions of reconditioned and new gravel road which will provide access to the lots as well as access to the storm drainage features. During the design of the storm drainage system a certain maximum allowable impervious area was designated to each lot. This area included the 2000-sf building sites as well as representative areas for driveways and outbuildings. Due to varying lot sizes the amount of impervious surface assumed for each lot varies. The areas assumed for each lot can be seen on the developed basin maps on pages B-3 and B-4 of Appendix B. UP-STREAM DRAINAGE BASIN* Due to topography along the west side of the site,runoff from 8.95-ac of adjacent parcel will enter the project area. This runoff will be collected by an interceptor ditch which will run parallel to the property line and adjacent to the proposed road. This ditch will collect the offsite flows from that area and direct those flows south and west to the unnamed stream. This can be seen on the Off Site Basin map page 10 Along the south edge of the property, flow from the unnamed stream will enter the parcel however those flows will pass through the area with out affecting the project area. Some additional off-site flow is possible along the south side of the east basin however the 3 Storm Drainage Report WestSound Engineering Fair Harbor Job #805.4 reconstruction of the road along that side should be sufficient to redirect that flow east to the wetland located along the east side of the project area. No off site flows are expected from the east and north as those areas are down stream from our site. DOWNSTREAM ANALYSIS: Once the developed runoff is detained and released it will follow existing contours through native vegetation and eventually discharge into either of the two wetland areas. All intercepted flow will also be directed to the adjacent wetland areas for discharge. The flow received in either wetland will proceed northeasterly and will eventually join at a point located off the northeast corner of the project site. Once combined these flows continue to flow north easterly until they are released into Case Inlet of the Puget Sound. See Figure 3 on page 10 for a topography map showing the course of the downstream flow. All discharges rates will be less than present rates however to ensure an adequate emergency overflow path exists for the East Basin the existing 12-inch CMP culvert will be replaced with an 18-inch ADS N-12 pipe. SOILS REPORT: Soils information was obtained from the USDA NRCS Web Soil Survey which provides user access to the information contained in the Soil Survey of Mason County Area, Washington. The data obtained from this website can bee seen on pages A-1 through A-3 of Appendix A GEOTECEMCAL, RF.PORT: A geotechnical report is not required.No structures are proposed on slopes greater than 30 percent. HYDROLOGIC ANALYSIS: As stated previously, a ridge separates the site into two hydrologic basins, East and West. The 1992 Storm Water Management Manual for the Puget Sound basin,referred to hence forth as "the manual", was used to dictate the design criteria for modeling the basins and their flows as well as sizing the BMP's proposed. The modeling of the existing,bypass, and developed conditions of these basins is shown in separate sections,below. SOIL TYPE According to the Soil Conservation Service,the project site contains "Alderwood gravelly sandy loam",which is a class"C" soil,`Bellingham silty clay loam",which is a class"D"soil, and "Sinclair shotty loam",which is a class"C" soil. A soils group table can be found on page A-4 of Appendix A. For the purposes of evaluating the soil runoff rates all soils were modeled as class"C" since the Bellingham soil is present only with in the wetland buffer along the east side of the east basin and no improvements are proposed in that area.Note the proposed gravel roads were modeled as 4 Storm Drainage Report WestSound Engineering Fair Harbor Job #805.4 impervious surfaces in both the bypass and developed models. This was done to provide for future paving. Paving is not specified in this current plan. DESIGN STORM EVENT PRECIPITATION The following precipitation values were obtained from Figures HI-1-44, III-1-45, and III-1-46 of the manual for the 2-yr, 10-yr, and 100-yr 24-hr storm design events. The value for the 6-month, 24-hr storm event was calculated as 64%of the 2-yr,24-hr storm precipitation value. 6-month 1.92-in 2-yr 3.00-in 10-yr 4.20-in 100-yr 5.90-in CALCULATION METHODS Santa Barbara Urban Hydrograph(SBUH)calculations were performed for the Type IA 24-hr storm using the commercial computer software"StormSHED2G". All pervious surfaces were modeled using the appropriate class"C"curve number obtained from the manual. TIME OF CONCENTRATION(Tc) The Tc for pervious and impervious surfaces was determined by evaluating the furthest point in each basin and evaluating the Tc resulting from that route as it followed existing contours. In this evaluation the furthest route refers to the route that develops the highest Tc value which is not necessarily the furthest in distance. In some cases the developed path was not sufficient to develop a Tc greater than 6-min. In these cases the area is considered to be "Directly Connected". For these cases a fixed Tc of 6-min was used. This corresponds to the minimum Tc value of 0.10-hr used in TR-55,the method on which the SBUH is based. EAST BASINS EAST EXISTING BASIN This sub-basin modeled the 4.46-ac of the east project site as 4.05-ac of"Wood/Forest Land (Young Second Growth/Brush)"and 0.41-ac of"Gravel Roads&Parking Lots". Both areas were modeled on class"C" soils. This resulted in the use of a CN of 89 for the gravel roads and a CN of 81 for the pervious surfaces. See page B-1, of Appendix B, for the Existing Basin Map and the associated Tc path computation. See page B-5 for the StormSHED report generated from this modeling. EAST BYPASS BASIN This sub-basin modeled a portion of the access road along the east side of the project site will be re-aligned and refurbished during the development of the infrastructure. Due to topography stormwater runoff for portions of this area will not be collected and sent to the detention system. Runoff from this area is considered bypass flow. 5 Storm Drainage Report WestSound Engineering Fair Harbor Job #805.4 The resulting East Bypass Basin modeled 0.12-ac of young second growth and the 0.12-ac of re-aligned refurbished gravel road. The pervious area was modeled using the CN of 81 as previously discussed in the existing condition. The reconditioned gravel road was modeled as impervious surface which resulted in a CN of 98. Due to the relatively short distance in which to develop the Tc value,the Tc for both land types was assumed to be 6-min. See page B-3, of Appendix B, for the Developed Basin Map showing the bypass basin. See page B-7 for the StormSHED report generated from this modeling. EAST DEVELOPED BASIN The developed condition modeled the 4.22-ac of the remaining east project site as 2.82-ac of "Open Spaces,Lawns, Parks (>75%grass)"and 1.40-ac of"Impervious Surfaces (Pavements, Roofs, Etc)". Both areas were modeled on class"C"soils. This resulted in the use of a CN of 86 for the open spaces and a CN of 98 for the impervious surfaces. See page B-3, of Appendix B, for a Developed Basin Map and associated Tc path computation. See page B-8 for the StormSHED report generated from this modeling. WEST BASINS WEST EXISTING BASIN The existing condition modeled the 2.96-ac of the west project site as 2.54-ac of"Wood/Forest Land(Young Second Growth/Brush)"and 0.42-ac of"Gravel Roads&Parking Lots". Both areas were modeled on class"C"soils. This resulted in the use of a CN of 89 for the gravel roads and a CN of 81 for the pervious surfaces. See page B-2, of Appendix B, for the Existing Basin Map and the associated Tc path computation. See page B-12 for the StormSHED report generated from this modeling. WEST BYPASS BASIN Due to topography runoff from a portion of the access road passing through the wetland and wetland buffer will not be collected and sent to the detention system. Developed flow from this area is considered bypass flow. The resulting West Bypass Basin modeled the 0.18-ac of the refurbished gravel road. The reconditioned gravel road was modeled as impervious surface which resulted in a CN of 98. Due to the relatively short distance in which to develop the Tc value,the Tc for both land types was assumed to be 6-min. See page B-4, of Appendix B, for the Developed Basin Map showing the bypass basin. See page B-13 for the StormSHED report generated from this modeling. WEST DEVELOPED BASIN The developed condition modeled the 2.82-ac of the remaining west project site as 1.71-ac of "Open Spaces, Lawns, Parks(>75% grass)"and 1.11-ac of"Impervious Surfaces (Pavements, Roofs,Etc)". Both areas were modeled on class"C" soils. This resulted in the use of a CN of 86 for the open spaces and a CN of 98 for the impervious surfaces. See page B-4, of Appendix 6 Storm Drainage Report WestSound Engineering Fair Harbor Job #805.4 B, for a Developed Basin Map and associated Tc path computation. See page B-14 for the StormSHED report generated from this modeling. WATER QUANTITY MITIGATION: To mitigate water quantity the manual establishes that the developed discharge from the project site is limited to no more than 50% of the existing 2-yr, 24-hr flow, 100% of the existing 10-yr, 24-hr flow and 100% of the existing 100-yr,24-hr flow. These limits are summarized below and can also be seen on the routing reports on pages B-9 and B-15 Table 1 East Basin West Basin Frequency Existing Bypass Limit Existing Bypass Limit 2- r 0.94 0.11 0.36 0.71 0.12 0.24 10- r 1.79 0.18 1.61 1.34 0.17 1.17 100- r 3.10 0.27 2.83 2.32 0.24 2.08 By evaluating the pond sizes and the control release units concurrently through a level pool routing process we were able to determine the pond size and orifice sizes required to mitigate the discharge. The process was performed using Storm SHED and the resulting information for each pond can be seen on the reports shown on pages B-10, B11, B-16 and B17 of Appendix B. Access to the east pond for sediment removal has been provided by a road that extends to the bottom of cell one. The long narrow shape of the west pond allows a backhoe sitting adjacent to the pond sufficient access to the pond bottom without the need of an access road. WATER QUALITY MITIGATION: To mitigate water quality the manual states that the 6-month storm volume must be mitigated for through the use of BMP's designed to treat water quality. Both the East Basin and the West Basin mitigate water quality through the use of wet ponds. The wet pond is a BMP that provides for storage of the entire volume of the 6-month storm in a pond cell at a depth of 3-ft to 6-ft. This pond then creates a sufficiently long residence time to allow for settling of suspended particles. The wet pond for the east basin was integrated into the forebay of the detention pond by excavating the additional volume required to contain the 6-month storm volume. The west basin uses a separate cell which is located between the inflow ditch and the first cell of the west detention pond. 7 Storm Drainage Report WestSound Engineering Fair Harbor Job #805.4 CONVEYANCE SYSTEM: The proposed features for this project include seven ditches, labeled Ditch 1 through Ditch 7, and eight pipes, labeled Pipe 1 through Pipe 9. The location of these features is shown on the Conveyance Map shown on page C-1 of Appendix C. The proposed storm drainage conveyance systems are designed to convey the peak runoff rate from the 100-yr, 24-hr storm event. Each portion of the conveyance system was isolated and the flows through that system were calculated using StormSHED2G. Due to the arrangement of the various conveyance features the East Basin was divided into four sub-basins and an additional 5th sub-basin was derived from the West Basin. These sub-basins were developed to assist in determining the peak flows that the various features would experience. To size the features the maximum capacity of each feature was computed using a spreadsheet developed in Excel. These spreadsheets use Manning's equation to determine that capacity, and they are shown on pages C-2 through C-5, of Appendix C and the max capacity as compared to the developed 100-yr flow is shown on Table 2, below. The basins are shown on the Conveyance Map, page C-1 and the basin reports can be seen on pages C-6 through C-11, of Appendix C. Table 2 Conveyance Feature Contributing Basin Peak Flow Proposed Size Capacity Pipe 1 West Basin 2.89 -cfs 12-in ADS N-12 3.86 -cfs Pipe 2 Sub-Basin 5 0.88 -cfs 12-in ADS N-12 3.86 -cfs Pipe 3 West Basin 2.00 -cfs 12-in ADS N-12 3.86 -cfs Pipe 4 East Basin 2.56 -cfs 12-in ADS N-12 3.86 -cfs Pipe 5 East Basin 2.56 -cfs 18-in ADS N-12 3.86 -cfs Pipe 6 Sub-Basin 4 2.25 -cfs 12-in ADS N-12 3.86 -cfs Pipe 7 Sub-Basin 2 1.12 -cfs 12-in ADS N-12 3.86 -cfs Pipe 8 Sub-Basin 1 1.29 -cfs 12-in ADS N-12 3.86 -cfs Ditch 1 West Basin 2.89 -cfs 1.5' "V"-Ditch 5.80 -cfs Ditch 2 Sub-Basin 5 0.88 -cfs 1.25' "v"-Ditch 2.70 -cfs Ditch 3 Off Site Basin 5.18 -cfs 1.5' W-Ditch 5.80 -cfs Ditch 4 Sub-Basin 3 1.02 -cfs 1.25' "V-Ditch 2.70 -cfs Ditch 5 Sub-Basin 2 1.12 -cfs 1.25' "v"-Ditch 2.70 -cfs Ditch 6 Sub-Basin 1 1.29 -cfs 1.25' "V-Ditch 2.70 -cfs Ditch 7 Sub-Basin 4 2.25 -cfs I 1.25' "v"-Ditch 1 2.70 -cfs TEMPORARY EROSION & SEDIMENT CONTROL: Temporary Erosion and Sediment Control (TESC) measures were designed to comply with the current Mason County standards. Control measures will include silt fencing, interceptor ditches, rock check dams, seeding and a temporary construction entrance, as a minimum. See construction plans for details. All disturbed areas will be revegetated according to the construction plans. The revegetated areas will either be hydroseeded or planted with suitable native plants. Refer to the construction plans for additional information. 8 Storm Drainage Report WestSound Engineering Fair Harbor Job #805.4 SUMMARY: In summary, the project will meet or exceed the minimum requirements of the Stormwater Manual for the Puget Sound Basin and the Mason County development standards. 9 FAIRHARBOR TRACTS A PORTION OF SECTION 5, TOWNSHIP 21 NORTH, RANGE 1 EAST, W.M. MASON COUNTY, WASHINGTON ;/ i y.� EDGE OF - ( ----- — _ MEP EXHIBIT MAP —/�--� ��--%"� _ °a e ICE LOT 1 I � ;� .:•: ,_��._ .rca 99YN,� S�/ TREASURE ISLAND RD ATWATER RD� / / 1 ' REACH LOT 2 (110 WMAND B �:YjF� ! I 1 ' Ep ISLAND � I I � RIM � claxr rSTEAST ORA LOT 3 � I j� i sITE I ; , SLAND NJ h ///� / � LOT 7 � �r _�� - I VICINITY MAP $ / LEGEND Nor m vu llll -- -�"� - - / •= i / Lie EXISTING MAJOR CONTOUR � �� ./ __ EXISTING MINOR CONTOUR / LOT 4 LOT I7 f• _- PROPt7ii1'LINE j� :a'a= : :s<:=is :::;<.::;.:j I I I :1:`:::;; I I — — AI1ucENr PARCEL I (t r t I as x"m r 110'rEILAND BUFFER J - - - EXISTING CULVERT 18 CLEAR SPACE / r _ —_ 1 'ti _.............._ ___......................__ _____ __ ADS N-12 OR ALUM. ® `.a.....--: '-;r=,S;T"`=.;�-:::_::::.;:;; — — — — — — — EDGE OF WETLANDS ._ . I EDGE OF : � / WETLANDS BUFFER WETLANDS EV ACCESS TURNAROUND / LOT 8/ I EDGE OF GRADING �...._....,......:.:.... STREAM BUFFER EDGE OF WETLANDS I// \ i -'-"Y f� _ PROPOSED DRA1NFlaD SEFnc _ - LOT 18 I __..._.......::.;::,:.....:............__...._'pi%aj _ _ _ _ CENTER OF STREW I ( f / I ! _ =d 'i ::••• APPROXIMATE TREE LINE I I ::a . •:ra::::::a::::_:. f:i^i%'==i`=:sS::_;_aa:`.a`•sT__:::_:_:-:'t-v:_: ......::::: LOSS I WETLANDS GAIN DENOTES MAXI MUM ' I s +az' i - 1 4 CORNER / SECTION BUFFER ENCROACH / J �.;�::. ! q / .►•� CT i ( �� IJ :: �F....:.= -;7y <_' ;''' , r .. WETLAND UNTY DESIGNATION FRONDED BY �p 1 _ / I �9'_ �.` rLOS� //L`::� :`i: ;_'-_;. '€� Ai:' a MASON COUNTY PUBLIC WORKS !/ T11 / / r BUFFER AVERAGE TABLE/ I - - - -- I'i l: J — — _ 110 i— !! /// o� .r —— — _• f ... 9. "� I _1 M1�A Iffi 9SN / / / / Jl r•A I �v / �� §`! ` J ._r'''?r' �I A 3533 SF AREA•�• _ :.:::;:.. I a 12 -- C 1322 SF — / -,_';a^ if E 2959 SF CULVERT TO I ANTICIPATED HIGH POINT IF 2774 SF I �— .... — _ — — — — -- REMAIN i 1 III I IN NEW ROO GRAVEL LOT 14 - / / / .I/ - hiJ �, rl I I I �{ L G 3433 SF -- 1J// / /.J AREAS SHOWN REPRESENT THE I \ /i I l MAXIMUM ALLOWABLE IMPERVIOUS AREA I I H -- 11622 SF ALLOTED TO EACH LOT IN THE STORMDRAINAGE LYSIS AND DO NOT AVERAGGED 95'wnm ofFFFR 1 _ / §/ \ I / I REFLECT THE ACTUAL BUILDING AREAS I I I -- 8185 SF - I I I r"l /lAl (T �� _ I , 1 I ( I TOTAL 18270 SF 27292 SF J J ! 3e/ 1 I PRIMARY AND RESERVE I ( -- ' I I DRNNFlEID AREA(TYP) I I GRAPHIC SCALE NET GAIN 9022 SF /9 ea 3o eo NOTE: -=- LO 18' / �• / rr §` W I I ( t I I t .B ALL IMPROVED ROADS DEPICTED ON THIS MAP SHALL INCLUDE �,- I I � / / ' / //, � 3 I , I I TITLE I EASEMENTS FOR INGRESS,EGRESS,UTILITIES AND STORM WATER. BUFFER1 /f I T. B FAIR HARBOR TRACTS DTjN �l1� // / IDESIGNED BY AWB C q11 MEP EXHIBIT MAP (30,(ff-2 ,W e s t S o u n d " WE�S,T�,A,�4 (. /I , rtar -�� DBAMBY �f Z Engineering, I n c / 6 f _�� 110,ME�O BUFFER 2t pbz ,Mr CLIENT 217 S.W.Wilkins Drive Port Orchard,Wa.98366 r/ @'"- JURGES ENTERPRISES INC. 1320'+/-� •�/ •�J A�/'� � �� � �`"���__ ��n• � ���SSIONAL�°\ Phone(360)876-3770 Fax(360)876-0439 i .A/ 1 18W/O - �'k/.Ek JE.1 E-mail:wse@wsengineeing.com httpJhvww.wsenginee6ng.com �—'�•-- SEC 5 TWN 21N R 1W 2020 ENETA BEACH ROAD BREMERTON,WA 98310 f /� I SCALE 1w REV. DFSCRPTION DATE By DATE SEALED (360)377-W4 JOB No. 805A SHT 1 OF 1 SHTS r N N N • r i � N N r'd. .lo O CD ! p7 ■ ■ O CEO vCr ''' N ■ �jc Ul N47°2`077-5' r 1 Ot `�r• rf} .rl f arbor i. .• Id as N47 art• Ja i R� t ■ .P Ir i •ri. +a r a it ■ � r+ i w f •: r y A 1+ 07 4 i 3-D TopoQuads Copyright©1999 DeLorme Yarmouth,ME, 04096 Source Data:USGS 250 ail:14-0 Datum:WGS84+ E N L.A(R G(-.,D 8 tl 17.0`d0 SAC! Y$C7Q OFrs.irE RPL-A OCC, x �PO,Xo-s� = 95 r�h�� �s A�surre� �o be �ouNS 5ess Nc� 6ro�{t�• 'L ` 6 goo I� IZ3 �Ctsf 2A0� i� s��ee* dp z C000 ►5 Sc, t�ow . a APPENDIX A County Reference Documents Soil Map—Mason County,Washington (Fair Harbor Tracts) 512100 512200 512300 512400 512500 512600 512700 512800 g IRV Ti VI m � N aN. - o • . t.,�;. • �- - N .[1 N o �r c ♦ o c 'y i a y N 512000 512100 512200 51&0 512400 512500 512600 5t_ St2800 N Meters 0 50 100 200 300 Feet 0 350 700 1.400 2,100 USDA Natural Resources Web Soil Survey 2.0 7/24/2007 Conservation Service National Cooperative Soil Survey Page 1 of 3 R1 Soil Map—Mason County,Washington (Fair Harbor Tracts) MAP LEGEND MAP INFORMATION Area of Interest(AOI) (Z Very Stony Spot Original soil survey map sheets were prepared at publication scale. Area of Interest(AOI) Viewing scale and printing scale,however,may vary from the 0 Wet Spot original.Please rely on the bar scale on each map sheet for proper Soils A Other map measurements. Soil Map Units Special Line Features Source of Map: Natural Resources Conservation Service Special Point Features ;L Gully Web Soil Survey URL: http://websoilsurvey.nres.usda.gov (9 Blowout Coordinate System: UTM Zone 1 ON Short Steep Slope ® Borrow Pit This product is generated from the USDA-NRCS certified data as of Other the version date(s)listed below. X. Clay Spot Political Features Soil Survey Area: Mason County,Washington Closed Depression Municipalities Survey Area Data: Version 4,Dec 5,2006 Gravel Pit Cities Date(s)aerial images were photographed: 6/21/1990 ., Gravelly Spot 0 Urban Areas The orthophoto or other base map on which the soil lines were ® Landfill Water Features compiled and digitized probably differs from the background Oceans imagery displayed on these maps.As a result,some minor shifting Lava Flow p - of map unit boundaries may be evident. r,► ,� Marsh N Streams and Canals x Mine or Quarry Transportation M 0 S Rails ® Miscellaneous Water Roads Perennial Water ow Interstate Highways v Rock Outcrop US Routes + Saline Spot State Highways Sandy Spot N Local Roads = Severely Eroded Spot Other Roads Sinkhole j Slide or Slip j Sodic Spot 31 Spoil Area a Stony Spot 00A Natural Resources Web Soil Survey 2.0 7/24/2007 Conservation Service National Cooperative Soil Survey Page 2 of 3 Soil Map—Mason County,Washington Fair Harbor Tracts Map Unit Legend Mason County,Washington(WA645) Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI Ab Alderwood gravelly sandy loam, 26.2 45.2% 5 to 15 percent slopes Be Bellingham silty clay loam,0 to 7.7 13.3% 3 percent slopes So Sinclair shotty loam,5 to 15 24.0 41.4% percent slopes Totals for Area of Interest(AOI) 57.9 100.0% USDA Natural Resources Web Soil Survey 2.0 7/24/2007 aim Conservation Service National Cooperative Soil Survey Page 3 of 3 A3 N Oi O% rl N U z z Q z A A u u m m m < Q Q < m Q < U U z z z z U z z z m z U A m y U U m A z A m Q z Q A m U U Q m z A m z Q a •� o0 z U) Q C z c o � O W O m a � u m ' _ 3 S o $ o 7 rA Say8, . � Sg $, '' � go � '� @ ° Eu3es � ]7 , Rb � u �, ocXb G' r` � u� ' > , ,, ._ 8 8 , , � o p ° eaoau� �n' �nrninrX ., on e ._ ._ �7 a 2 � o 0 W W C7 C7 C� C� C7 C7 x x x S x x x x .. .. of vl of v� ul w tq N v) vl rn vl ? a Q y u H umuUmmmmummu umQAumuPzPzUmmm < mum euuu2zumzQzumcaUa mz2mCm < 0 < u p z O •,� > a T W b x O x g a H f~' O � En ? _ > 6 6 tot pp ^T yy a� pp Ic 1.0 < � � �So3dr� a� o8s$ o�or� � uu" u" u" ciuuiva52a .� 3aaz' z' zz" STORMWATER MANAGEMENT MANUAL FOR THE PUGET SOUND BASIN Table III-1.3 SCS Western Washington Runoff Curve Numbers (Published by SCS in 1982) Runoff curve numbers for selected agricultural, suburban and urban land use for Type lA rainfall distribution, 24-hour storm duration. LAND USE DESCRIPTION CURVE NUMBERS BY HYDROLOGIC GROUP A B C D Cultivated land(1) : winter condition 86 91 94 95 Mountain open areas: low growing brush & grasslands 74 82 89 92 Meadow or pasture: 65 78 85 89 Wood or forest land: undisturbed 42 64 76 81 Wood or forest land: young second growth or brush 55 72 81 86 Orchard: with cover crop 81 88 92 94 open spaces, lawns, parks, golf courses, cemeteries, landscaping. Good condition: grass cover on z75% of the 68 80 ;_86 90 area Fair condition: grass cover on 50-75% of 77 85 90 92 the area Gravel roads & parking lots: 76 85 89 91 Dirt roads & parking lots: 72 82 87 89 Impervious surfaces, pavement, roofs etc. 98 98 9 98 open water bodies: lakes, wetlands, ponds etc. 100 100 100 100 Single family residential(2) : Dwelling Unit/Gross Acre %Impervious(3) Separate curve number 1.0 DU/GA 15 shall be selected for 1.5 DU/GA 20 pervious & impervious 2.0 DU/GA 25 portions of the site 2.5 DU/GA 30 or basin 3.0 DU/GA 34 3.5 DU/GA 38 4.0 DU/GA 42 4.5 DU/GA 46 5.0 DU/GA 48 5.5 DU/GA 50 6.0 DU/GA 52 6.5 DU/GA 54 7.0 DU/GA 56 PUD's, condos, apartments, %impervious commercial businesses & must be industrial areas computed (1) For a more detailed description of agricultural land use curve numbers refer to National Engineering Handbook, Sec. 4, Hydrology, Chapter 9, August 1972. (2) Assumes roof and driveway runoff is directed into street/storm system. (3) The remaining pervious areas (lawn) are considered to be in good condition for these curve numbers. III-1-12 FEBRUARY, 1992 STORMWATER MANAGEMENT MANUAL FOR THE PUGET SOUND BASIN Table III-1.4 "n" AND "k" Values Used in Time Calculations for Hydrographs "n," Sheet Flow Equation Manning's Values (for the initial 300 ft. of travel) n, smooth surfaces (concrete, asp a t, grave , or bare -hand packed soil) 0.011 Fallow fields or loose soil surface (no residue) 0.05 Cultivated soil with residue cover (ss 0.20 ft/ft) 0.06 Cultivated soil with residue cover (s> 0.20 ft/ft) 0.17 Short prairie grass and lawns 0.15 Dense grasses 0.24 Bermuda grass 0.41 Range (natural) 0.13 Woods or forest with light underbrush 0.40 Woods or forest with dense underbrush 0.80 *Manning values for sheet flow only, from Overton and Meadows 1976 (See TR-55, 1986) "k" Values Used in Travel Time/Time of Concentration Calculations Shallow Concentrated Flow (After the initial 300 ft. of sheet flow, R = 0.1) k. 1. Forest with heavy ground litter and meadows (n = 0.10) 3 2. Brushy ground with some trees (n = 0.060) 5 3. Fallow or minimum tillage cultivation (n = 0.040) 8 4. High grass (n = 0.035) 9 5. Short grass, pasture and lawns (n = 0.030) 11 6. Nearly bare ground (n = 0.25) 13 7. Paved and gravel areas (n = 0.012) 27 Channel Flow (intermittent) (At the beginning of visible channels R = 0.2) kc 1. Forested swale with heavy ground litter (n = 0.10) 5 2. Forested drainage course/ravine with defined channel bed (n = 0.050) 10 3. Rock-lined waterway (n = 0.035) 15 4. Grassed waterway (n - 0.030) 17 5. Earth-lined waterway (n = 0.025) 20 6. CMP pipe (n = 0.024) 21 7. Concrete pipe (0.012) 42 8. Other waterways and pipe 0.508/n Channel Flow (Continuous stream, R = 0.4) k c 9. Meandering stream with some pools (n = 0.040) 20 10. Rock-lined stream (n = 0.035) 23 11. Grass-lined stream (n = 0.030) 27 12. Other streams, man-made channels and pipe 0.807/n** III-1-16 FEBRUARY, 1992 4 FRIDAY HA :.40 NE K� ' Z 1 V-z is 45 d. • .cam oil am 45 lAj fit 40 35 fool It Pr INCH 1 1 1 1 1 I � 1. � •'' • i �i • • OLGA FRIDAY HAR13OR PORT TA 20/ 4;. , . , Saw -4 o Olf it -021 P- • r • APPENDIX B Hydrologic Analysis / ! 4 4 -N- Existing Tc 3 1 - 150-LF • S - 6.7% (Sheet) 2 — 90-LF a S - 6.7% (Shallow) GRAPHIC SCALE ,a 3 - ,h8-LF • S - 2.5% (Shallow) CH FEFO 1 Ind-000 feet 4 - 215-LF • S - 0.5% (Shallow) 1 1 Existing Areas: Pervious Surface Area 4.05-ac (Young Second Growth) Impervious Surface 0.41-ac /\ — — (Gravel Roads) Total Area 4.46-ac J East Bann Existing Conditions / Ma �1 ,► p 11 � l I I I I I Ill Existing Tc_ (Sheet) I '* ) -N- XCRI 492 GRAPHIC SCALE 40 Existing Areas. ;.: Pervious Surface Area 2.54-ac (Young Second Growth) Impervious Surface 0.42-ac (Gravel Roads) Total Area 2.96-ac West Basin Existing Conditions ix Map I x x \ ` t _N 51 G� J ry � GRAPHIC SCALE n � f Bypass Tc ,3 Assumed to be 6-min I I Developed Tc Bypass Areas Pervious Surface Area 0.12-ac 1 - 150-LF a S - 1.0% (Sheet) (Young Second Growth) �000 -- 2 - 480-LF S - 1.0% (Channel) Impervious Surface 0.12-ac 50 i (Gravel Roads) Total Area 0.24-ac x Developed Areas: 1 - ~\ Pervious Surface Area 2.82-ac (Young Second Growth) / 750 Impervious Surface 1.40-ac L (Gravel Roads) Total Area 4.22-ac East Basin Bypass & Developed Yp p = Co n dition M s a p Li -Iv- - i- Yp t�( =`_ / B ass Tc — 50 �"~ x s: ` - Assumed to be 6-min / x Developed Tc l/\ GRAPHIC SCALE 1 - 160-LF S t1.3% (Sheet) +0 b 1 2 - 200-LF • S - 1.0% (Channel) 'i.h-80 fwt III - 1 l 1 1 x / Bypass Areas: i f Pervious Surface Area 0.00-ac N: 1 (Young Second Growth) Impervious Surface 0.18-ac (Gravel Roads) Total Area 0.18-ac r ! r .`� -> -�` -,.r„ t .r � F,•,rF,G r�- _� � .��"`:-.e�9"'`S 'G t , < �.,�,... .�[s ��'= �, ' `''%'stil-<.,y`C-s;'l'F+. ,;� Developed Areas: Pervious Surface Area 1.71-ac (Young Second Growth) Impervious Surface 1.t1-ac (Gravel Roads) Total Area 2.82-ac r / West Basin Bypass & Develo ped ed �. 240 Conditions Map ffiR Page 1 of 2 Appended on: 14:48:33 Tuesday, June 10,2008 East Existing Basin Event Summary Event Peak Q (c lPeak T hrs H d Vol a lRaintypel 6 month 0.2448 8.17 0.1921 4.4600 SBUH TYPEIA 2 year 0.9414 8.17 0.5082 _JF4.4600 SBUH TYPElA 10 year 1.7887 8.17 0.8760 4.4600 SBUH TYPE 1 A 100 yearj 3.0997 8.17 1 1.4385 4.4600 SBUH TYPE 1 A Record Id: East Existing Basin Design Method I UH IFRainfall type [ TYPE 1 A H d Intv 1 10.00 min lPeaking Factor 484.00 Abstraction Coeff 0.20 Pervious Area 4.05 ac DCIA 0.41 ac Pervious CN 11 81.00 IIDC CN 89.00 Pervious TC 25.46 min ILDC TC 25.46 min Pervious CN Calc Description SubArea Sub en Wood/forest land(young 2nd growthibrush) 4.05 ac 81.00 Pervious Composited CN (AMC 2) 81.00 Pervious TC Calc T e Description Len th Sloe Coeff Misc TT Sheet Woods or forest with light underbrush.: 0.40 150.00 ft 6.70% 0.4000 3.00 in 18.91 min Shallow Brushy ground with some trees (n=0.0 11.08 min Shallow Brushy ground with some trees (n=0.0 12.32 min Shallow Brushy ground with some trees (n=0.060) 215.00 ft 0.50% 0.0600 3.14 min Pervious TC IL5.46 min Directly Connected CN Calc Description I SubArea Sub cn Gravel Roads & Parking Lots 1 0.41 ac IL 89.00 DC Composited CN (AMC 2) 89.00 Directly Connected TC Calc T e Description Len th Sloe Coeff Misc TT Sheet Woods or forest with light underbrush.: 0.40 150.00 ft 6.70% 0.4000 3.00 in 18.91 min Shallow Brushy ground with some trees (n=0.060) 90.00 ft 6.70% 0.0600 1.08 min 9-5 file://X:\Projects\Active\800's\805.4 Fairharbor Tracts\Engineering\Design\Storm\805.4 - ... 6/10/2008 Page 2 of 2 Shallow (Brushy ground with some trees (n=0.0 12.32 min Shallow Brushy ground with some trees (n=0.060) 215.00 ft 0.50% 0.0600 3.14 min Directly Connected TC 25.46min Licensed to: Professional License 'b(I,- file://X:\Projects\Active\800's\805.4 Fairharbor Tracts\Engineering\Design\Storm\805.4 - ... 6/10/2008 Page 1 of 1 Appended on: 13:11:35 Tuesday, June 10, 2008 East Bypass Basin Event Summary Event Peak Q (cQ) IPeak T hrs) 1HYd Vol acft Area ac Method Rain e 6 month1 0.0552 8.00 JI 0.0206 0.2400 SBUH TYPElA 2 year1 0.1143 8.00 0.0408 0.2400 SBUH TYPElA 10 year 0.1786 8.00 0.0625 0.2400 SBUH TYPE 1 A 100 year 0.2734 8.00 0.0945 0.2400 SBUH TYPEIA Record Id: East Bypass Basin Desi n Method SBUH Rainfall type TYPE 1 A H d Intv 10.00 min IFPeaking Factor 484.00 Abstraction Coeff 0.20 Pervious Area 0.12 ac DCIA 0.12 ac Pervious CN 81.00 DC CN 98.00 Pervious TC IL 6.00 min IFDC TC 6.00 min Pervious CN Cale Description SubArea Sub cn Wood/forest land(young 2nd growth/brush) 0.12 ac 81.00 Pervious Composited CN (AMC 2) 81.00 Pervious TC Calc T e DescriptionI Length ISloe Coeff Misc TT Fixed 6.00 min Pervious TC 6.00 min Directly Connected CN Cale Description SubArea 11 Sub cn Impervious surfaces (pavements, roofs, etc) 0.12 ac 98.00 DC Composited CN (AMC 2) 98.00 Directly Connected TC Calc T e Description Length Sloe Coeff Misc TT Fixed 6.00 min Directly Connected TC 11 6.00min Licensed to: Professional License file://X:\Projects\Active\800's\805.4 Fairharbor Tracts\Engineering\Design\Storm\805.4 - ... 6/10/2008 Page 1 of 2 Appended on: 14:49:54 Tuesday,June 10, 2008 East Developed Basin Event Summary Event Peak Q c IPeak T hrs)jHyd Vol acft Area ac Method Rain e 6 month 0.8131 8.00 0.3485 4.2200 SBUH TYPEIA 2 year 1.7367 8.00 0.7136 4.2200 SBUH TYPEIA 10 year 2.7304 8.00 1.1036 4.2200 SBUH TYPEIA 100 year 4.1784 8.00 1.6744 4.2200 SBUH TYPE 1 A Record Id: East Developed Basin Desi n Method SBUH Rainfall type TYPE IA H d Intv 10.00 min -]Peaking Factor 484.00 Abstraction Coeff 0.20 Pervious Area 2.82 ac DCIA 1.40 ac Pervious CN 86.00 DC CN 98.00 Pervious TC =1 23.18 min DC TC -6.64 min Pervious CN Calc Description I SubA I Sub cn Open spaces, lawns,parks (>75% grass) 2.82 ac 86.00 Pervious Composited CN (AMC 2) 86.00 Pervious TC Calc Tye Description Len th Sloe Coeff Misc TT Sheet Short prairie grass and lawns.: 0.15 150.00 ft 1.00% 0.1500 3.00 in 18.47 min Channel (intern) Grassed (n=0.030) 480.00 ft 1.00% 0.0300 4.71 min Pervious TC 23.18 min Directly Connected CN Calc Description SubArea Sub cn Impervious surfaces (pavements, roofs, etc) 1.40 ac 98.00 DC Composited CN (AMC 2) 98.00 Directly Connected TC Calc T e Description Len th Sloe Coeff Misc TT Sheet Smooth Surfaces.: 0.011 150.00 ft 2.00% 0.0110 3.00 in 1.73 min Channel (intern) Grassed (n=0.030) 500.00 ft 1.00% 0.0300 4.91 min Directly Connected TC 6.64min 3Q file://X:\Projects\Active\800's\805.4 Fairharbor Tracts\Encineeriniz\Design\Storm\R05 4 - 6/1 ni?nnQ Page 1 of I Appended on: 08:23:42 Wednesday, June 11, 2008 West Existing Basin Event Summary Event Peak Q (cfs)IlPeak T (hrs) 1HYd Vol (a IRaintypel 6 month 0.1958 8.17 0.1322 2.9600 SBUH TYPElA 2 year 0.7144 8.00 0.3445 2.9600 SBUH TYPEIA 10 year 1.3448 8.00 0.5902 2.9600 SBUH TYPEIA 100 year 2.3180 8.00 0.9651 2.9600 SBUH TYPElA Record Id: West Existing Basin Desi n Method SBUH Rainfall type IFTYPEIA H d Intv 1 10.00 min IPeaking Factor 1484.00 Abstraction Coeff 0.20 Pervious Area 2.54 ac IDCIA I ac Pervious CN 81.00 DC CN 89.00 Pervious TC 20.22 min DC TC 6.00 min Pervious CN Calc Description SubArea Sub cn Wood/forest land(young 2nd growthlbrush) 2.54 ac 81.00 Pervious Composited CN (AMC 2) 81.00 Pervious TC Calc T e Description Len th Sloe Coeff Misc TT Sheet Woods or forest with dense underbrush.: 0.80 100.00 ft 12.00% 0.8000 3.00 in 18.86 min Shallow Brushy ground with some trees (n=0.060) 152.00 ft 12.00% 0.0600 1.37 min Pervious TC 20.22 min Directly Connected CN Cale Description SubArea Sub cn Gravel Roads & Parking Lots 0.42 ac IL 89.00 DC Composited CN (AMC 2) 89.00 Directly Connected TC Calc T e Descr E Length Sloe Coeff Misc TT Fixed 6.00 min Directly Connected TC 6.00min Licensed to: Professional License b-iZ file://X:\Projects\Active\800's\805.4 Fairharbor Tracts\Engineering\Design\Storm\805.4 - ... 6/11/2008 Page 1 of 1 Appended on: 13:33:20 Tuesday, June 10, 2008 West Bypass Basin Event Summary Event Peak Q cfs Peak T hrs H d Vol acft Area ac Method Rain e 6 month 0.0706 8.00 0.0236 0.1800 SBUH TYPEIA 2 year 0.1218 8.00 0.0415 0.1800 SBUH TYPEIA 10 year 0.1725 8.00 0.0595 0.1800 SBUH TYPElA 100 year 0.2438 8.00 0.0849 0.1800 SBUH TYPE 1 A Record Id: West Bypass Basin Design Method I BUH IFRainfall type TYPE 1 A H d Intv 10.00 min IlPeaking Factor 484.00 Abstraction Coeff 6.20 Pervious Area 0.00 ac IDCIA I0.18 ac Pervious CN 0.00 DC CN 1= 98.00 Pervious TC 0.00 min DC TC 6.00 min Directly Connected CN Calc Description SubArea Sub cn Impervious surfaces (pavements, roofs, etc) 0.18 ac 98.00 DC Composited CN (AMC 2) 98.00 Directly Connected TC Cale T e Descri7p-tion-T Length Sloe Coeff Misc TT Fixed 6.00 min Directly Connected TC 6.00min Licensed to: Professional License a- 13 file://X:\Projects\Active\800's\805.4 Fairharbor Tracts\Engineering\Design\Storm\805.4 - ... 6/10/2008 Page 1 of 2 Appended on: 14:58:17 Tuesday, June 10, 2008 West Developed Basin Event Summary Event Peak Q cfs Peak T hrs H d Vol acft Area ac Method Rain type 6 month1 0.6077 j 8.00 0.2316 2.5800 SBUH TYPE 1 A 2 year 1.2627 8.00 0.4597 2.5800 SBUH TYPElA 10 year 1.9586 8.00 0.7009 2.5800 SBUH TYPEIA 100 year 2.9659 8.00 1.0522 2.5800 SBUH TYPElA Record Id: West Developed Basin Desi n Method SBUH IrRainfall type IFTYPEIA H d Intv 10.00 min IlPeaking Factor 1 484.00 Abstraction Coeff 0.20 Pervious Area 1 1.47 ac IDCIA 1.11 ac Pervious CN 11 86.00 DC CN 98.00 Pervious TC 9.34 min DC TC 1=34 min Pervious CN Calc Description bArea IL Sub cn Open spaces, lawns,parks (>75% grass) 1.47 ac 86.00 Pervious Composited CN (AMC 2) 86.00 Pervious TC Cale Type Description ILen th Sloe Coeff Misc TT Sheet Short prairie grass and lawns.: 0.15 160.00 ft 11.30% 0.1500 3.00 in 7.37 min Channel (interm) Grassed (n=0.030) 200.00 ft 1.00% 0.0300 1.96 min Pervious TC 9.34 min Directly Connected CN Calc Description SubArea 11 Sub cn Impervious surfaces (pavements, roofs, etc) 1.11 ac 98.00 DC Composited CN (AMC 2) 98.00 Directly Connected TC Calc Type Description Len th Sloe Coeff Misc TT Sheet Short prairie grass and lawns.: 0.15 160.00 ft 11.30% 0.1500 3.00 in 7.37 min Channel (interm) Grassed (n=0.030) 200.00 ft 1.00% 0.0300 1.96 min Directly Connected TC 9.34min 6 �lU file://X:\Projects\Active\800's\805.4 Fairharbor Tracts\Engineering\Design\Storm\805.4 - ... 6/10/2008 Page 1 of 1 Appended on: 10:35:38 Wednesday, June 11, 2008 LPOOLCOMPUTE [West Routing] SUMMARY using Puls Start of live storage: 485.9000 ft Event Match Q cfs Peak Q cfs Peak St ft ITime to Emptyl 6 month1 0.0000 0.1572 487.4095 2312.73 0.0531 35.00 2 year 0.2400 0.2337 11 488.9938 6483.32 0.1488 41.83 10 year 1.1700 1.0034 j 489.2257 7239.61 0.1662 43.67 100 yearj 2.0800 2.0046 489.7324 9080.35 0.2085 43.83 Licensed to: Professional License 3-tS file://X:\Projects\Active\800's\805.4 Fairharbor Tracts\Engineering\Design\Storm\805.4 - ... 6/11/2008 Page 1 of 1 Appended on: 10:36:03 Wednesday,June 11, 2008 Record Id: West Pond Descrip: Prototype Record Increment 0.20 ft Start El. 485.9000 ft Max El. 490.0000 ft Stage Area Stage (ft) ea s 485.90 0.0000 486.00 1321.0000 487.00 1921.0000 488.00 2558.0000 489.00 3234.0000 490.00 4274.0000 Stage Storage Rating Curve 485.9000 ftIl 0.0000 cf 488.1000 ft 4185.7222 cf 486.1000 ftIl 201.1419 cf 1488.3000 ft 4724.3618 cf 486.3000 ftIl 489.3419 cf 488.5000 ft 5290.0420 cf 486.5000 ftIl 801.5419 cf 488.7000 ft 5882.7617 cf 486.7000 ftII 1137.7419 c 488.9000 ft 6502.5220 cf 486.9000 ftII1497.9419 c 489.1000 ft 7151.1421 cf 487.1000 ftII1882.3269 c 489.3000 ft 7839.5420 cf 487.3000 ft112292.0068 c 489.5000 ft 8569.5420 cf 487.5000 ftIJ2727.1670 c 489.7000 ft 9341.1416 cf 487.7000 ft113187.8069 c 489.9000 ft 10154.3418 c 487.9000 ft113673.9270 c 490.1000 ft 10998.7164 c Licensed to: Professional License 13 -16 file://X:\Projects\Active\800's\805.4 Fairharbor Tracts\Engineering\Design\Storm\805.4 - ... 6/11/2008 Page 1 of 2 Appended on: 10:36:15 Wednesday, June 11, 2008 Record Id: West Orifice Descrip: Prototype S lIncrement 0.20 ft Start El. 486.0000 ft Max El. 497.0000 ft Orif Coeff 10.62 1Lowest Orif El. 484.00 Lowest Diam 12.2500 in Dist to next 3.0000 ft D2 9.0000 in Dist to next 0.0000 ft Stage Discharge Rating Curve 486.0000 ft 0.0000 cfs 491.6000 ft 3.8694 cfs 486.2000 ft 0.0614 cfs 491.8000 ft 4.0090 cfs 486.4000 ft 0.0869 cfs 492.0000 ft 4.1437 cfs 486.6000 ft 0.1064 cfs 492.2000 ft 4.2742 cfs 486.8000 ft 0.1229 cfs 492.4000 ft 4.4006 cfs 487.0000 ft 0.1374 cfs 492.6000 ft 4.5235 cfs 487.2000 ft 0.1505 cfs 492.8000 ft 4.6431 cfs 487.4000 ft 0.1626 cfs 493.0000 ft 4.7597 cfs 487.6000 ft 0.1738 cfs 493.2000 ft 4.8734 cfs 487.8000 ft 0.1843 cfs 493.4000 ft 4.9845 cfs 488.0000 ft 0.1943 cfs 493.6000 ft 5.0931 cfs 488.2000 ft 0.2038 cfs 493.8000 ft 5.1995 cfs 488.4000 ft 0.2128 cfs 494.0000 ft 5.3037 cfs 488.6000 ft 0.2215 cfs 494.2000 ft 5.4058 cfs 488.8000 ft 0.2299 cfs 494.4000 ft 5.5061 cfs 489.0000 ft 0.2380 cfs 494.6000 ft 5.6045 cfs 489.2000 ft 1.2288 cfs 494.8000 ft 5.7013 cfs 489.4000 ft 1.6435 cfs 495.0000 ft 5.7964 cfs 489.6000 ft 1.9633 cfs 495.2000 ft 5.8899 cfs 489.8000 ft 2.2338 cfs 495.4000 ft 5.9820 cfs 490.0000 ft 2.4729 cfs 495.6000 ft 6.0727 cfs 490.2000 ft 2.6894 cfs 495.8000 ft 6.1620 cfs 490.4000 ft 2.8890 cfs 496.0000 ft 6.2501 cfs 490.6000 ft 3.0750 cfs 496.2000 ft 6.3369 cfs 490.8000 ft 3.2500 cfs 496.4000 ft 6.4225 cfs 491.0000 ft 3.4158 cfs 496.6000 ft 6.5070 cfs 491.2000 ftl 6.5904 cfs 491.4000 ftl 6. 7728 cfs 7 file://X:\Projects\Active\800's\805.4 Fairharbor Tracts\Engineering\Design\Storm\805.4 - ... 6/11/2008 APPENDIX C Conveyance Analysis I I— - I List of Conveyance Features PIPE 1 - 12" ADS N-12 PIPE 1 PIPE 2 - 12" ADS N-12 - _ PIPE 3 - 12" ADS N-12 PIPE 4 - 12" ADS N-12 PIPE 5 - 12" ADS N-12 -- _ PIPE 6 - 12" ADS N-12 - - PIPE 7 - 12" ADS N-12 DITCH 1 PIPE S - 12" ADS N-12 W PIPE 9 - EX 12" CMP _ DITCH 1 - 1.50' V-DITCH DITCH 2 - 1.25' V-DITCH DITCH 3 - 1.50' V-DITCH _ _ DITCH 4 - 1.25' V-DITCH PIPE 2 - DITCH 5 - 1.25' V-DITCH DITCH 6 - 1.25' V-DITCH DITCH 7 - 1.25' V-DITCH I DITCH 2 DITCH 3 Sub-Basin 5 I 0.25-ac Impervious 0.50-ac Pervious I 0.75-ac Total I Conveyance Map C-1 Proposed 12-inch ADS N-12 WestSound Engineering 5/27/2008 2:01 PM Fair Harbor Designed By: CJM Project No. 805.4 Checked By: CTB Input Data Manning's Coefficient n = 0.012 "n" per Manual Channel Slope So = 0.01 ft/ft Min design slope Pipe Diameter D = 12 in Design diameter Discharge Q = 3.86 cfs Q,00yr(undetained peak) Results Depth Yn = 0.74 ft Yn = 8.85-in < 12-in ok Percent Full % = 73.7 % Flow Area A = 0.62 sq ft Wetted Perimeter P = 2.07 ft Hydraulic Radius Rh = 0.30 ft Top Width Tw= 0.88 ft Velocity V= 6.22 ft/s Critical Depth Yc = 0.70 ft Froude Number Fr= 1.305 Flow is supercritical Full Flow Capacity QfU11 = 3.86 cfs QN11 > Q100yr .. ok C-2 Existing 12-inch CMP WestSound Engineering 5/27/2008 2:01 PM Fair Harbor Designed By: CJM Project No. 805.4 Checked By: CTB Input Data Manning's Coefficient n = 0.024 "n" per Manual Channel Slope So = 0.063 ft/ft Min design slope Pipe Diameter D = 12 in Design diameter Discharge Q = 4.74 cfs Q100yr(undetained peak) Results Depth Yn = 0.49 ft Yn = 5.92-in < 12-in ok Percent Full % = 49.4 % Flow Area A = 0.39 sq ft Wetted Perimeter P = 1.56 ft Hydraulic Radius Rh = 0.25 ft Top Width Tw= 1.00 ft Velocity V= 12.27 ft/s Critical Depth Yc = 0.90 ft Froude Number Fr= 3.480 Flow is supercritical Full Flow Capacity Qf,,,, = 4.84 cfs Qfull > Q oo r .. ok C-3 1.25' "V"-Ditch WestSound Engineering 5/27/2008 2:00 PM Fair Harbor Designed By: CJM Project No. 805.4 Checked By: CTB Input Data Manning's Coefficient n = 0.03 'In" per Manual Channel Slope So = 0.01 ft/ft Min Design Slope Right Side Slope mr= 2 H:1V Left Side Slope ml = 2 HIV Bottom Width B= 0 ft Discharge Q= 2.7 cfs Q100yr(combinnes undetained and upstream) Results Depth Yn = 0.75 ft .75' (Depth) + 0.5' (Freeboard) = 1.25' Flow Area A= 1.13 sq ft Wetted Perimeter P= 3.36 ft Hydraulic Radius Rh = 0.336 ft Top Width Tw= 3.00 ft Velocity V= 2.394 ft/s Critical Depth Yc= 0.65 ft Froude Number Fr= 0.689 Flow is subcritical X:\Projects\Active\800's\805.4 Fairharbor Tracts\Engineering\Design\Storm\805.4- 1.25-ft Ditch 1 C-4 1.50' "V"-Ditch WestSound Engineering 5/27/2008 2:00 PM Fair Harbor Designed By: CJM Project No. 805.4 Checked By: CTB Input Data Manning's Coefficient n = 0.03 'In" per Manual Channel Slope So= 0.01 ft/ft Min Design Slope Right Side Slope mr= 2 HIV Left Side Slope ml = 2 HIV Bottom Width B= 0 ft Discharge Q = 5.8 cfs Qlooyr(combinnes undetained and upstream) Results Depth Yn = 1.00 ft 1.0' (Depth) + 0.5' (Freeboard) = 1.5' Flow Area A= 2.00 sq ft Wetted Perimeter P = 4.47 ft Hydraulic Radius Rh = 0.447 ft Top Width Tw= 4.00 ft Velocity V= 2.898 ft/s Critical Depth Yc= 0.88 ft Froude Number Fr= 0.722 Flow is subcritical X:\Projects\Active\800's\805.4 Fairharbor Tracts\Engineering\Design\Storm\805.4- 1.5-ft Ditch 1 C-5 Page 1 of 1 Appended on: 09:57:37 Tuesday, May 27, 2008 Sub-Basin 1 Event Summary Event Peak Q (e 1HYd Vol (acft Area (ac Method Rain e 6 month 0.1654 8.00 0.0701 1.2000 SBUH TYPElA 2 year 0.4644 8.00 0.1662 1.2000 SBUH TYPEIA 10 year 0.7997 8.00 0.2728 1.2000 SBUH TYPElA 100 year 1.2937 8.00 0.4314 1.2000 SBUH TYPE 1 A Record Id: Sub-Basin 1 Desi n Method SBUH IFRainfall type TYPElA Hyd Intv 10.00 min [Peaking Factor 484.00 Abstraction Coeff 0.20 Pervious Area 1.20 ac DCIA 0.00 ac Pervious CN 86.00 DC CN 0.00 Pervious TC 6.00 min 7EDC TC 0.00 min Pervious CN Calc Description SubArea Sub cn Open spaces, lawns,parks (>75% grass) 1.20 ac 86.00 Pervious Composited CN (AMC 2) 86.00 Pervious TC Cale T e Description Length Sloe Coeff Misc TT Fixed 6.00 min Pervious TC 6.00 min Licensed to: Professional License file://X:\Projects\Active\800's\805.4 Fairharbor Tracts\Engineering\Design\Storm\805.4 - ... 5/27/2008 Page 1 of 1 Appended on: 09:57:52 Tuesday, May 27, 2008 Sub-Basin 2 Event Summary Event Peak Q (cfs) Peak T (hrs)IlHyd Vol (acft) IRaintypel 6 month 0.2577 8.00 0.0911 0.9100 SBUH TYPE 1 A 2 year 0.5029 8.00 0.1740 0.9100 SBUH TYPElA 10 year 0.7582 8.00 0.2605 0.9100 SBUH TYPE 1 A 100 year 1.1248 8.00 0.3856 0.9100 SBUH TYPElA Record Id: Sub-Basin 2 Desi n Method I BUH IFRainfall type IF TYPElA jyd Inty 10.00 min Peaking Factor 484.00 Abstraction Coeff 0.20 Pervious Area 0.39 ac JLDCIA 0.52 ac Pervious CN 86.00 DC CN 98.00 Pervious TC 6.00 min DC TC IL 6.00 min Pervious CN Calc Description SubArea Sub cn Open spaces, lawns,parks (>75% grass) 0.39 ac 86.00 Pervious Composited CN (AMC 2) 86.00 Pervious TC Calc Tye Descri tion Length Sloe Coeff Misc TT Fixed 6.00 min Pervious TC 6.00 min Directly Connected CN Cale Description SubArea 11 Sub en Impervious surfaces (pavements, roofs, etc) 0.52 ac 98.00 DC Composited CN (AMC 2) 98.00 Directly Connected TC Calc T e Descri tion Length Sloe Coeff Misc TT Fixed 6.00 min Directly Connected TC 6.00min Licensed to: Professional License e-i file://X:\Projects\Active\800's\805.4 Fairharbor Tracts\Engineering\Design\Storm\805.4 - ... 5/27/2008 Page 1 of 1 Appended on: 09:58:06 Tuesday, May 27, 2008 Sub-Basin 3 Event Summary Event Peak Q (c IPeak T hrs) H d Vol (acft)]Area (ac) Method Rain e 6 month 0.1962 8.00 0.0727 0.8700 SBUH TYPEIA 2 year 0.4237 8.00 0.1482 0.8700 SBUH TYPElA 10 year 0.6673 8.00 0.2287 0.8700 SBUH TYPEIA 100 year 1.0209 8.00 0.3465 0.8700 SBUH TYPEIA Record Id: Sub-Basin 3 Desi n Method I BUH IFRainfall type TYPEIA H d Intv 11 10.00 min IPeaking Factor 484.00 Abstraction Coeff F 0.20 Pervious Area 0.57 ac DCIA 0.30 ac Pervious CN 86.00 JDC CN 98.00 Pervious TC =1 6.00 min DC TC IL 6.00 min Pervious CN Calc Description bArea IL Sub cn Open spaces, lawns,parks (>75% grass) 0.57 ac 86.00 Pervious Composited CN (AMC 2) 86.00 Pervious TC Calc T e Description Length Sloe Coeff Misc TT Fixed 6.00 min Pervious TC 6.00 min Directly Connected CN Calc Description SubArea 11 Sub cn Impervious surfaces (pavements, roofs, etc) 0.30 ac 98.00 DC Composited CN (AMC 2) 98.00 Directly Connected TC Calc T e Description Len th Sloe Coeff Misc TT Fixed 6.00 min Directly Connected TC 6.00min Licensed to: Professional License C -8 file://X:\Projects\Active\800's\805.4 Fairharbor Tracts\Engineering\Design\Storm\805.4 - ... 5/27/2008 Page I of 1 Appended on: 09:58:21 Tuesday, May 27, 2008 Sub-Basin 4 Event Summary Event Peak Q IPeak T (hrs) jHyd Vol (acft) Area (ac Method Rain e 6 month 0.4087 8.00 0.1540 1.9500 SBUH TYPEIA 2 year 0.9141 8.00 0.3208 1.9500 SBUH TYPElA 10 year 1.4600 8.00 0.5000 1.9500 SBUH TYPElA 100 year 2.2543 8.00 0.7628 1.9500 SBUH TYPEIA Record Id: Sub-Basin 4 Design Method SBUH 1Rainfall type TYPEIA H d Intv 10.00 min Peaking Factor F 484.00 Abstraction Coeff 0.20 Pervious Area 1.40 ac DCIA F 0.55 ac Pervious CN 86.00 DC CN 98.00 Pervious TC 6.00 min DC TC 6.00 min Pervious CN Calc Description I SubArea Sub cn Open spaces, lawns,parks (>75% grass) =11.40 ac 86.00 Pervious Composited CN (AMC 2) 86.00 Pervious TC Cale T eI Descri Lion Length Sloe Coeff Misc TT Fixed 6.00 min Pervious TC 6.00 min Directly Connected CN Calc Description SubArea Sub cn Impervious surfaces (pavements, roofs, etc) 0.55 ac 98.00 DC Composited CN (AMC 2) 98.00 Directly Connected TC Calc T e Description IF Length Sloe Coeff Misc17 TT Fixed 6.00 min Directly Connected TC JE 6.00min Licensed to: Professional License C 9 file://X:\Projects\Active\800's\805.4 Fairharbor Tracts\Engineering\Design\Storm\805.4 - ... 5/27/2008 Page 1 of 1 Appended on: 14:45:26 Tuesday, May 27, 2008 Sub-Basin 5 Event Summary Event Peak Q (cfs Peak T (h jHyd Vol (acft) Area (ac) Method Rain e 6 month 0.1670 8.00 0.0620 0.7500 SBUH TYPElA 2 year 0.3627 8.00 0.1269 0.7500 SBUH TYPElA 10 year 0.5728 8.00 0.1963 0.7500 SBUH TYPE 1 A 100 year 0.8777 8.00 0.2977 0.7500 SBUH TYPEIA Record Id: Sub-Basin 5 Desi n Method I BUH Rainfall e TYPElA H d Intv 10.00 min Peaking Factor 484.00 Abstraction Coeff F0.20 Pervious Area 0.50 ac ILDCIA 0.25 ac Pervious CN 86.00 DC CN 98.00 Pervious TC 6.00 min DC TC 6.00 min Pervious CN Calc Description I SubArea Sub cn Open spaces, lawns,parks (>75% grass) 0.50 ac 86.00 Pervious Composited CN (AMC 2) 86.00 Pervious TC Calc T e Descri FLength JSloe Coeff Misc TT Fixed 6.00 min Pervious TC 6.00 min Directly Connected CN Calc Description SubArea 11 Sub cn Impervious surfaces (pavements, roofs, etc) 0.25 ac 98.00 DC Composited CN (AMC 2) 98.00 Directly Connected TC Calc Die Descr ELength Sloe Coeff Misc TT Fixed 6.00 min Directly Connected TC 6.00min Licensed to: Professional License bo file://X:\Proj ects\Active\8 00's\8 05.4 Fairharbor Tracts\Engineering\Design\Storm\805.4 - ... 5/27/2008 Page 1 of 1 Appended on: 13:52:50 Tuesday, May 27, 2008 Off Site Event Summary Event Peak Q (c IPeak T (hrs) H d Vol (acft)]Area ac Method Rain e 6 month 0.3753 8.67 0.3592 8.9500 SBUH TYPElA 2 year 1.4691 8.17 0.9796 8.9500 SBUH TYPEIA 10 year 2.9101 8.17 1.7084 8.9500 SBUH TYPEIA 100 year 5.1766 8.17 2.8287 8.9500 SBUH TYPElA Record Id: Off Site Desi n Method SBUH IFRainfall type TYPElA H d Into 1 10.00 min IPeakin Factor 484.00 Abstraction Coeff 0.20 Pervious Area 8.95 ac IIDCIA 0.00 ac Pervious CN 1 81.00 DC CN 0.00 Pervious TC 40.27 min DC TC 0.00 min Pervious CN Calc Description SubArea 11 Sub cn Wood/forest land (young 2nd growth/brush) 8.95 ac 81.00 Pervious Composited CN (AMC 2) 81.00 Pervious TC Cale T e Description ILen th Sloe Coeff Misc TT Sheet Woods or forest with dense underbrush.: 0.80 2 0.00 13.13% 0.8000 n00 3r67 Shallow ft Forest n re0s10j heavy ground litter& meadows 600.00 13.13% 0.1000 8.60 min Pervious TC 40.27 min Licensed to: Professional License C-1I file://X:\Projects\Active\800's\805.4 Fairharbor Tracts\Engineering\Design\Storm\805.4 - ... 5/27/2008