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HomeMy WebLinkAbout03368 - Technical Information Report BAIMA & HOLMBERG INC. � P�- �3��. s m M TECHNICAL INFORMATION REPORT for Wills Short Plat March 31,2006 I��viS�D � � /z� O(� 12�v�5�fl �'�� � �' _�I�i PE � � w��.�.,�,' � � ~riY I `� G " � �,�. _ � � � � � '� 'S �r�� (� � :� 1 ,, ��I(j�lall_�r`I`lti. E?;PIP.ES 11 .'�0:'Og Baima & Holmberg, Inc. Job No. 2135-006 Prepared For Greg Wills 11250 S.E. 293rd Street Auburn,WA 98092 100 FRONT STREET SOUTH • ISSAQUAH • WASHINGTON • 98027-3817 • (425) 392-0250 • (425)391-3055 33�8 TABLE OF CONTENTS SECTION TITLE 1 PROJECT OVERV�W 2 CONDITIONS AND REQUIIZEMENTS SUNIlVIARY 3 OFFSTTE ANALYSIS 4 FLOW CONTROL AND WATER QUALITY FACILITY ANALYSIS AND DESIGN 5 CONVEYANCE SYSTEM ANALYSIS AND DESIGN 6 SPECIAL REPORTS AND STUDIES 7 OTHER PERNIITS 8 ESC ANALYSIS AND DESIGN 9 BOND QUANT`ITIES,FACILITY SUMMARIES,AND DECLARATION OF COVENANT 10 OPERATIONS AND MAIlVTENANCE MANUAL , SECTION 1 PROJECT OVERVIEW j ,- Project Overview This project involves the development of a 1.20-acre parcel into 7 single-family lots. The site is located at 2009 Talbot Road South. A house, garage, lawn and an assortment of outbuilding currently occupy the site. The site slopes down to the west at about 5%to 10%. Per the SCS soil maps, the site is underlain with Beausite soil—a thin layer of sandy loam over sandstone. I Proposed Drainage Control Included calculations show that the site is exempt from detention requirements. A water quality tank will provide the required runoff treatment. A storm system will be constructed in the adjacent private road, routing runoff from the site beyond the adjacent lot and its water problems. I ���: , . � ; : . �. _ �,� . : �� „ . . � �, ;'� �_� ,: . , F_ ��� : �' � _� �-� . ; , � y � `� ; t__: ;� i ..., , t� i.�� � �: _, I _- • .� � ,dRr P �r ,�� ,..,, � � ,� �� �� "�...." �-"" � � " . � �' ,� ..�- ,�^^"' '"w- ..� '"""' � I O 1 � �. ...-� ''"` �.,.�- � il � �,,. � ""~ \ �-° , � , � ,.,... ,.- \ o � � � � �,' ` '" � ; �� � �� o e o �. ` �, � �, ���2' +�„ �. Q�" � � �r r `` � � 5 `O , , Y 1� B /�/� � � GE EP A. 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Mt \ ' �� J .I �...� n+ ��"N \ ,.:w� � ....., �. �, ,�,,� � � � ,... - . _ � King County Department of Development and.Environmental Services TECHNICAL INFORMATION REPORT (TIR) WORKSHEET Part 1 °PRO:lECT=OWNER;AND,- Part 2 .<PROJECT;LOCATION'AND - PROJECTENGINEER � : DESCR1PTfON Project vrner � ` Project Name �j2�.`4 Wt C.�-S _ W 1 �t,S Sl-�9n-7 �Li+j- Address Location 1_ � 7_S� �� Z�j,�f�_D 5r Township Phone Range _ �_ Project Eng' eer ••�••Section 731riL4 Company /4� � J� Address/Phone ��D �d�T S ( s , `Part 3�.=-TYPE::�F P,ERMIT = Rart 4 :OTHER=REUIEWS�AND_PERMiT.S;;= ... . .:� : -APP.LICATION - > _ Subdivison � DFW HPA Shoreline Management )( Short Subdivision COE 404 Rockery Grading � � � DOE Dam Safety Structural Vaults Commercial FEMA Floodplain Other = Othzr COE Wetlands _ _ , ;Part 5'�SITE`COIVtM�JNfTY.AND.�RAiI�tAGE BASIN -" Community �� ti X� . Drainage Basin �/ �<���� � /� (i V : . _ ,�. - _ - Part 6;`SITE`CHARACTERISTICS _ - River Floodpfain Wetlands Stream Seeps/Springs � Critical Stream Reach High GroundwaierTable Depressions/Swales Groundwater Recharge Lake Other Steep Slopes . ..: ,. .. _ - - Part7':SO1LS � �,. : ; _ � . .::' . . _ Soil Type Slopes Erosion Potential Erosive Velcoties -�b���.-- � �d llno�JfT-TT� Additional Sheets Attached Pait 8:,DEVELOP..IVIENT L1MlTATIONS` __ - REFERENCE LIMITATION/SITE CONSTRAINT Ch. 4-Downstream Ana(vsis � Additional Sheets Attached P._art 9,.:'ESC.REQUIREMENTS.��„. - .:,��_:; - _ � -. ,.; - , - :.. . .., - ;� __. - : _ �_: - - Y . � MINIMUM ESC REQUIREMENTS MINIMUM ESC REQUIREMENTS DURING CONSTRUCTION AFTER CONSTRUCTION ✓Sedimentation Facifities . ✓Stabilize Exposed Surface . �Stabilized Construction Entrance - .. �Remove and Restore Temporary ESC Facilities �Perimeter Runoff Control -- ✓Clean and Remove All Silt and Debris �Clearing and Graing Restrictions �Ensure Operation of Permanent Facilities ✓Cover Practices .�Flag Limits of SAO and open space �Construction Sequence preservation areas Other Other � =Part'f0 :SURFAGE WATER SYSTEM ,:;� : - Method of Analysis Grass tined Tank Infiltration � Channel Vault Depression s�v Pipe System Energy Dissapator Flow Dispersai Compensation/Mitigati Open Channel on of S oraaeed Site Wetland Waiver 9 � Dry Pond � Stream Regional Wet Pond Detention Brief Description of System Operation �DLL�G� �I��F I � �i�5 t . Facifiiy Related Site Limitation Reference Facility Limitation , � ._. :: , .. . �:: _ _ ry _ � -, =;part�11 STRUCTURAL AIJALYS[S Patt`]2 FASEMEl�1TS�1'RACTS,T _ - - Cast in Place Vault Drainage Easement Retaining Wall Access Easement Rockery>4'High Native Growth Protection Easement : Structural on Sieep Slope Tract � Other � Other �. _ . ..- � ._ -.:.,: .._ . �Part;13, SIGNATURE�F=PROFESSIONAL€NGINEER �:; _ ` : � . i or a civil engineer under my supervision my supervision have visited the site. Actual site conditions as observed were incorporated into this worksheet and the attachments. To the best of my knowledge the information provided here is accurate. 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', _ _ _ _ � � � �� i , ��--- . !_ — __ SECTION 2 CONDITIONS AND REQUIRMENTS S Y i- SECTION 3 OFFSITE ANALYSIS � Project Overview This project involves the development of a 1.20-acre parcel into 7 single-family lots. The site is located at 2009 Talbot Road South. A house, garage, lawn and an assortment of outbuilding currently occupy the site. The site slopes down to the west at about 5%to 10%. Per the SCS soil maps,the site is underlain with Beausite soil—a thin layer of sandy loam over sandstone. Level 1 Downstream Drainage The site drains west to an adjacent lot and to the adjacent private street cul-de-sac. Drains along the east side of the adjacent lot direct flows though perforated and tightlines to the drainage system in Shattuck Avenue South, about 250' to the west. Runoff onto the cul- de-sac flows west along the private street, collecting in two catch basins at the intersection of the private street and Shattuck (A). Flows drain west from the CB's though a 12"pipe to a 18" storm system at the west side of Shattuck. The 18" flows north to South 19�' Street (B), turns west and continues to the intersection of 19�' and Lake Avenue South (C), continues west over the hill and discharges west(D), draining into a swampy area adjacent to the east side of SR-167, well over '/4 mile downstream from the site. Other than nuisance water problems on the adjacent lot,there were no obvious downstream drainage problems. Proposed Drainage Control Included calculations show that the site is exempt from detention requirements. A water quality tank will provide the required runoff treatment. 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Three sheds and a garage also are located on the site. The topography on the site slopes at an average gradient of 6 to 8 percent from east to west. The site ranges in elevation from 220 feet on the east boundary to 200 feet on the west boundary. The predominant cover type on the 1.2-acre site is lawn with clumps of mature trees (Table 4.1). The site generally slopes from the northeast to the southwest. Based on the King County Soil Survey(U.S. Department of Agriculture, 1973) the site consists of Beausite soils (Section 1). This soils series is categorized as Hydrologic Soils Group C. The site is surrounded by existing single-family development. Drainage from 0.11 acre of existing impervious along Talbot Road South sheet flows to the project site. Drainage sheets from the project site sheet flows to the west and is ultimately collected in the storm system along Shattuck Avenue South. Part B: Developed Site Hydrology The proposal for development includes building 6 single-family dwellings in addition to the existing dwelling, which will remain. Existing outbuildings on the site will be removed. Access to Lot 1 will be from a private cul-de-sac off of Shattuck Avenue South. Access to Lots 2—6 will be from a proposed private road off Talbot Road South. Improvements along Talbot Road South are also planned. Under developed conditions,the plat, including the existing residence and offsite improvements will consist of 0.44 acre of lawn/landscape and 0.80 acres of impervious area. In addition, runoff from 0.11 acre of existing impervious will be collected from Talbot Road South. Cover type areas for developed onsite conditions are summarized in Table 4.1. Stormwater from the site (subbasin "dev") will be collected and treated onsite in a wet tank. Discharge from wet tank pond will be tightlined to an existing storm system located on the west side of Shattuck Avenue South. A perforated drainage pipe will be installed along the west boundary of Lot 1 and connected to the proposed conveyance system to improve drainage conditions for the adjacent neighbor. Based on an SBUH analysis of the 100-year peak flow rates for existing and proposed developed conditions, the predicted increase in flow rates is less than 0.5 cubic foot per second, and flow control is therefore not required(Part D of this section). The impervious area for the project was calculated as follows: Lots: 4,000 sf/lot x 71ots = 28,000 sf= 0.64 ac Roads/sidewalks: 6,970 sf= 0.16 ac Existing impervious from Talbot Road= 4,792sf= 0.11 ac I 0.91 ac Table 4.1. Existing and Developed Site Basin Conditions Ezistin Conditions CN=81 CN=86 CN=98 Till- Till- Till- Subbasins Site forest pasture Wetland grass Imperv Total Basin AC (AC (AC AC AC (AC Site exis 0.60 0.50 0.10 1.20 Offsite Road Improvements ezis 0.04 0.11 0.15 Total 0.60 - - 0.54 0.21 1.35 Develo ed CondiNons CN�81 CN=86 CN=98 Till- Till- Till- Subbasins Site forest pasture Wetland grass Imperv Total Basin (AC) (AC) (AC) (AC) (AC) (AC) Onsite Lots/Road* dev 0.44 0.91 1.35 * Road and sidewalk areas were measured from the site plan. ** An area of 0.11 acre of existing impervious contributes to the site under existing and proposed developed conditions. Part C: Performance Standards A summary of flow control, conveyance, and water quality treatment performance standards for the project is presented in Table 4.2, below. Table 4.2. Summary of Performance Standards Cate o Performance Standard Source Flow Control • Exempt(flow rate increase less ■ 1990 Surface Water than 0.5 cfs) Design Manual i Plat Conveyance System ■ Provide conveyance for ■ 1990 Surface Water Capacity developed 25-year storm Design Manual Water Quality Treatment ■ Wet tank ■ 1990 Surface Water Menu Design Manual Section 4.4.5 Part D: Flow Control System The predicted increase in the 100-year/24-hour storm for developed versus existing basin conditions is less than 0.5 cubic foot per second. Based on provisions in the 1990 Surface Water Design Manual, The proposed development plan is exempt from flow control requirements. The SBUH model was used to predict the 100-year/24-hour peak flow rates for both existing and proposed developed conditions. The predicted peak flow rate for existing conditions was 0.60 cubic foot per second versus 1.07 cubic feet per second proposed developed conditions. Documentation of the SBUH modeling results is provided in Appendix A of this report. Part E: Water Quality System ' A water quality tank will provide treatment for the site. The tank size was determined using i procedures provided in the 1990 Surface Water Design Manual. The required dead storage volume �_ in the tank is equivalent to the predicted runoff volume of the water quality storm for the developed site. The water quality storm was assumed to have a precipitation amount equal to be 1/3 of the 2- year stor/24-hour storm (Section 1.3.5 of the 1990 Surface Water Design Manua�. The SBUH model predicted a required water quality storage volume of 1,665 cubic feet. This volume includes that required to treat runoff from the portion of Talbot Road South that will be collected in the onsite storm system. Documentation of the SBUH modeling results is provided in Appendix A of this report. The water quality tank is also required to provide a surface area at the top of the permanent pool equal to or greater than 1 percent of the impervious area draining to the tank. The required surface area is therefore 396 square feet. A 6-foot diameter tank will be used in the design. The water quality storage depth in the tank will extend from a depth of 0.5 foot to 4.5 feet. The volume provided in the tank is 1,685 cubic feet with a surface area of 406 square feet at a storage depth of 4.5 feet. Calculations for the wet tank quantities provided in the proposed design are shown Appendix B. SECTION 5 CONVEYANCE SYSTEM ANALYSIS AND DESIGN Proposed Stormwater Conveyance System A conservative modeling approach was used to check the conveyance capacity of the proposed 12- I, inch diameter storm system. This system conveys collected stormwater from the site to the water ' quality tank and from the water quality tank to the connecting catch basin in Shattuck Avenue South (CB#1). The Rational method was used to calculate the 100-year peak flow rate for the entire developed site (Table A.1). The 100-year peak flow rate was calculated to be 2.97 cubic feet per second. A backwater analysis was then conducted for the proposed conveyance system(Table A.2). The 100-year peak flow rate for the entire site was assumed to flow through the pipe system. Hydraulic results show that the 100-year peak flow rate is conveyed through the system with adequate freeboard. ExisNng Stormwater Conveyance System—Shattuck Avenue South Stormwater from the site will discharge to the conveyance system along Shattuck Avenue South. The hydraulic capacity of this system was evaluated as described below. Contributin Bg asins In effort to develop a hydrologic model of the basins contributing to the conveyance system along Shattuck Avenue South,basin boundaries were delineated using the following resources: ■ City of Renton aerial topography (1-meter contours) ■ Field verification of key locations in the watershed The study area under consideration is shown in Figure 5.1. Cover types within the study area include those associated with relatively dense single-family residences, forest, and pasture. Soils in the watershed are of the Beausite series. This series is considered to be Hydrologic Soils Group C. In total, an area of 25.44 acres was calculated to drain to the downstream end of the conveyance system evaluated(Table 5.1). Assuming full build-out conditions, the basin would conservatively have about 60 percent of the contributing area in effective impervious surfaces. A total of 4 subbasins were delineated(Figure 5.2). The size and boundaries of the delineated subbasins draining to the conveyance system were driven by the locations of catch points and the watershed's topography. �Qth � O � of m � v �L r , o = �`Qas _ i ' i --- �� � � � � � ��oy _ ` _—_ �stn \` �stn � + T� I __w... -'1 �-, _ ��� 1 I ; ,_ . � �� � V .f 4. , ' �, � E ; � . _ .. _ � , � � � 16th �� -- 1 ; 1 ---�- ; � , i i V I � O � W u1 �l�i 17tf1 I ` �� ��; ,'�� � � ;' „[� , , m . � - �,---- �,'� - ' ,a�n �� �� � ' � ��, � �; � _ f � 1 �f-- - . � ����,_ _ , I cn 1 `�_ , (�i � m 19th ' _ _ _ � ''BeC 19th _ i ' c _ _ _ � I � _19th 3 w � - ^-r--r--�--,--, -- - 00 rn qy ' Ur i , i `� t_ ___ _ � � + ,: ,__ ' ' 2otn Project i i Site � ','� Pu N f _,___ 2an ___ ___. ; - - , ; B`'("i o __ ��...,�..,�.__ ' . � 21 � � i ' - ___.___, � Conveyance ; ; ' _ � 1 System o � � Basins � 22n '� N 2 Si� SU11 � _. ___— ?2 �— —,---�I �L � ' ' j I � J; ' � �+� � � + 23rd I _ .� ` 23rd �� I � � � � _ �3 ''a __�/� � � � � . 1 � S , � _ r�;f � � I i , I.. 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J���,, •• .�! � ��wt , �7• �� �- `. v�s � ��' �( �,.� �� s� '�� 'y, $� Y � ` _ l� :;��' �'�y ,�,:,. �a��� �l �-� Il �,, �1- �- + , ���, � ._.; �'. � �{{{{���� 15 }� vt� _ ��` 1 �t �� ��� _`\ ,�.�1' \\F�. ��N A� � �,Jt, "�f�#.t vj�� ��� _ .�.. f� �r �� '��� �� ��;�F�-�.� 1 .. . - 4 �'_ � .... � w��..�1�V � �1t�� �_�_.. . _ - �.. __ . . - . ._.>. . . � - .�, � ��'i . i �i 4 y » �s' }� , �r - ' ��:� , - - € �tf 4 ��'�ta�` "� � . � ��� � \ �`a � ,3�••. �� ,� �'. �.�� — ��R ��� : ��� f � , �� �`F ;� ,�, �� � {,� v � � �`;��. � � $ � �"►•► `�s�,�. ����r} �. ',tt }- J �R'" .�y A R � ,_ .. � ir.-� �� , �-1� �kl�'.. ��� .. .. \�i ���� .� � u �> �-i�` t �,. �� Pv�No Basin Map � Wills Short Plat Drainage Analysis 9957171stAvenueSE �s�2��o� 250 Fternon,washington 98059 King County, Washington Feet F�0"e: (425)271-5734 Figure 5.3 (425)271-3432 '' Table 5.1. Contributing Basins to Shattuck Avenue Basin ID Grass Impervious Total AC AC AC A 1.98 2.98 4.96 B 1.37 2.05 3.42 C 4.29 6.43 10.72 D 2.54 3.80 6.34 ' Total 10.18 15.26 25.44 Hvdrology Assessment of Contributin� Basins The hydrologic model Stormshed was used to estimate peak flow rates for each of the basins contributing to the conveyance system(Appendix B.l). The SBUH model was used in estimating peak runoff rates for the 25-year and 100-year storms. Peak flow rates for the 25-year and 100-year return periods at key locations along the conveyance system are shown in Figure 5.3. The peak rates associated with the 25-year and 100- year return periods for each of the contributing basins are listed in Appendix C. The flow rates from contributing basins are likely conservative for the following reasons: ■ The cover types are based on full-build out conditions, assuming 60 percent impervious. ■ No attenuation of hydrographs is included in the model for existing or future stormwater detention facilities. One detention tank is located in Subbasin C. ■ No attenuation of flow is included in the model for storage in the pipe system. Hvdraulic Analvsis of Conve, a�vstem The conveyance system along Shariuck Avenue South consists primarily of an 18-inch diameter pipe located along the west side of the road. The conveyance system flows south along Shattuck Avenue South. At CB#Sl, located at the intersection of 19`�' Street South, the pipe system turns to the west. Downstream from CB#S 1, the diameter apparently reduces to 12 inches. The slope of the pipe increase as the system turns to the west. In addition, the pipe inverts at this location are relatively deep (9 to 10 feet). The system capacity was evaluated from CB#S 1 located at the intersection of 19`t' Street, to upstream CB#S5. Pipe diameters and lengths were measured in the field. Pipe inverts were measured down from the catch basin rims. 'The rim elevations of the pipes were estimated using City of Renton GIS topography. The input data for the hydraulic analysis therefore meet the standards of a King County Leve12 downstream drainage analysis. A backwater analysis was conducted for the existing conveyance system(Table C.l). The downstream boundary condition at CB#S 1 assumed a hydraulic depth of 6 feet to account for the likely inlet control conditions for water exiring CB#S1. Modeling results show that the 25-year peak flow rate is conveyed entirely within the pipe system with at least 0.5 foot of freeboard. The 100-year peak flow rate is predicted to be contained within all catch basins except CB#S5. Being lower than the road surface, overflow from CB#SS would likely sheet flow to the northwest in a natural drainage swale. I t��� i%� ' �� � y� , � � ��' � �� f� � � � � � � � � / ` 1 ��1 `i. ' 1 � �� '����} � � ��`, ,, , , � � � ,�,�i �. -� � -� , ! I �`` � � Q25 = 14.96CFS � J !�. � �. 'I � � ) ` �, � `, Q100= 17.69 CFS �� " � � � \ ' ' �r _ __ ' �� ) -�- , r I ,� � \ CB#S 1 � ��� � �i �.�����°. „ �� _ _ � � � � �; � � 12 12 19th Street ---�i � L_'_ ��� �s„ , 7 , , i; 'I ��' � � ! I ;�� Q25= 11.32 CFS , CB#S2 1/ `,' �%� �� �i� Q100= 13.41 CFS ' i �� � � � � j� � �� , � � i' ;� ,� _� � '';. X �,� � , _F/r � , � � I i, / '��;�� ��� - ' � % �j � v� ��� � , � , � , , �� ,� ;�- ���- _ , ,��� � . � X )�� '��� ' `�, ' � �' y, � > l � ' '� j , � ' % � � � � � , ,, ,�� Q ; � � �� � /, ��i X ' � � �, '`, A, � L Y � �I � � � ) �' �� i - � � � � 18 � ' -,� '' ( � � - , , _ : --�_---� � ��_ � � � � � � � ;� � �� �- �� ,.. ' � � ��. :� ---- � �� �� � ? -r ) ���� _ >>�-� I , �_ Q25—8.29 CFS � l ; , 1 I � � : Q100= 9.84 CFS���-� CB#S3 ��` �i ' ��1 �� � �' � \ _s,-� __ ; i; �,� : .� , �, � �� .\� �` _ R_ _ � s . ,, / � �g � � � ,- , , ��.� _ ,��,,,� , CB#S4 - ,. - �__�____ _-- _ 12° �`� -, (�5 =6.16 CFS � C a � � �� L Q100= 7.23 CFS i �-\ CB#S5 Project �-- � �� � , Site � J ; ,; ; � > ) . r ( �- � / � � r�� � , j j � ; � � � � �� � �� � , ;� �� , ;; _ ; : � � � \. ;\�, .� ii,J , � ' ' \ � 1 �' j�.f,' ; � ���� � �' � � 1 �, , \ ' � \ � l � � + ' 1 � � \ � ! _. � l lj r \\\\ ������: �c t �._ � __ _-- � _ 1 ! / � � � � , ) ; � - ���-�- _�j' � � ''��,��' , / t +F ! rl 1 \ ���x\��� '', `'�' �T �j � � � ! � � � ��. , �,���t����� . � � r� � i < <� � � �� � � �,��� �, ������ ��\�.�,�, — — � / � ' i � � i ���\�\` \\�\\ ' ���.+�k- �� —i_— - ---���--- ( ' _.i � - ��;\�� � \,`� \�, � \1'`��\�_- > � � � � � � � � � � J �� � � / � � ��,\�,�� \ i � �ti��� , ,\ \� �, `� � , � i , � / / � �. � r ���' '��`\ ' �, \�\ \-\� - t � , = ��.��.� �\ �\\ �����. , } t� � % , , \\ �� ,.�; -� \ ��1 \� � , . �\�i ���, j i� \���`..\,���, X �� Shattuck Ave. S. Conveyance System � - ' �,b Wills Short Plat Drainage Analysis 9957171stAvenueSE 7�2�°� 100 Renron,washington 98059 King County, Washington Feet �one: (425)271-5734 Figure 5.2 Fax: (425)271•3432 I SECTION 6 SPECIAL REPORTS AND STUDIES c/1 F-� . � � � Z O a C.�,) � - W �� H O SECTION 8 ESC ANALYSIS AND DESIGN SECTION 9 BOND QUANTITIES, FACILITY SUMMARIES, AND DECLARATION OF COVENANT SECTION 10 OPERATIONS AND MAINTENANCE I��IANUAL � I ; i � �� � . , Appendix A. Onsite Stormwater Design Hydrologic Modeling Results Precipitation [2 yr] = 2.00 in [100 yr] = 3.90 in [1NQ] _ (1/3)` [2 yr] = 0.67 in Contributing Drainage Areas Drainage Area: Dev Hyd Method: SBUH Hyd Loss Method: SCS CN Number Peak Factor: 484.00 SCS Abs: 0.20 Storm Dur: 24.00 hrs Intv: 10.00 min Area CN TC Pervious 0.4400 ac 86.00 0.11 hrs Impervious 0.9100 ac 98.00 0.11 hrs Total 1.3500 ac Supporting Data: Pervious CN Data: Prototype subarea 86.00 0.4400 ac Impervious CN Data: lmp 98.00 0.8000 ac Road 98.00 0.1100 ac Pervious TC Data: Flow type: Description: Length: Slope: Coeff: Travel Time Fixed None Entered 0.00 ft 0.00% 6.3000 6.30 min Impervious TC Data: ' Flow type: Description: Length: Slope: Coeff: Travel Time Fixed None Entered 0.00 ft 0.00% 6.3000 6.30 min Drainage Area: Exis Hyd Method: SBUH Hyd Loss Method: SCS CN Number Peak Factor: 484.00 SCS Abs: 0.20 Storm Dur: 24.00 hrs Intv: 10.00 min Area CN TC Pervious 1.1400 ac 83.00 0.34 hrs Impervious 0.2100 ac 98.00 0.34 hrs , Total 1.3500 ac Supporting Data: Pervious CN Data: Prototype subarea 83.00 1.1400 ac ' Impervious CN Data: ' Imp 98.00 0.1000 ac Exis Imp Talbot 98.00 0.1100 ac Pervious TC Data: � Flow type: Description: Length: Slope: Coeff: Travel Time Fixed None Entered 0.00 ft 0.00% 20.5000 20.50 min ' Impervious TC Data: Flow type: Description: Length: Slope: Coeff: Travel Time Fixed None Entered 0.00 ft 0.00°/a 20.5000 20.50 min Hydrograph Routing MOVEHYD [Exis] TO [Exis - 100 yr]AS[100 yr] Peak Flow: 0.5991 cfs Peak Time: 8.00 hrs Hyd Vol: 11896.24 cf-0.2731 acft MOVEHYD [Dev]TO [Dev- 100 yr]AS [100 yr] Peak Flow: 1.0676 cfs Peak Time: 8.00 hrs Hyd Vol: 16029.64 cf-0.3680 acft MOVEHYD [Exis] TO [Exis -WQ]AS [WQ] Peak Flow: 0.0195 cfs Peak Time: 8.00 hrs Hyd Vol: 482.34 cf- 0.0111 acft MOVEHYD [Dev]TO [Dev-WQ] AS [WQ] Peak Flow: 0.1072 cfs Peak Time: 8.00 hrs Hyd Vol: 1664.91 cf-0.0382 acft � II � Table A.1. Flow Rate Calculations Using the Rational Method - 100-year Flow Design Storm = 100 yr 24 Hr Precip = 3.9 in Sub SubArea Pasture Lawn Impervious Total Tc ir I Q Basin Subtotat C=020 C=0.25 C=0.90 Area C C*A Unit Peak (SF) (AC) (AC) (AC) (AC) (MIN) (IN/HR) (CFS) Develop 58,806 - 0.43 0.91 1.35 0.69 0.93 6.30 0.82 3.19 2.96 Site Total 58,806 - 0.43 0.91 1.35 2.96 v1.1 Project: Will's Short Plat Table A.2. Backwater Analysis for Proposed Conveyance System Date: 07/02/07 Offsite Conveyance Improvements: CB1 to Water Quality Tank 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 20 Pipe BaRel Barrel Barrel Friction Entrance Entrance Entrance Exit Exit Outlet Inlet Inlet Approach Bend Bend Bend HW Top Pi e Se ment Q Length Size "n" Outlet Elev Inlet Elev Area Velocity Vel Head TW Elev Loss HGL Elev HL HL HL HL Cntrl. Elev Control Cntrl. Elev Vel. Head Defl. HL HL Elev. Upstream CB to CB (cfs ft (in) Value ft ft (sfl (fps ft) ft) ft ft Ccef (ft) Coef (ft (ft HW/D ft ft de Ccef ft ) (ft) Structure C61 CB2 2.96 244 12 0.012 196.25 196.00 0.785 3.77 0.22 197.25 1.42 198.67 0.50 0.11 1.00 0.22 199.00 1.23 197.23 0.22 0 0.02 0.00 198.79 199.20 ..................... ..... ...... .......................... ....................... ..................................... ................................................ .......... . ............................... ............... . .............................................. ..........................................--�- -.............................................--�--........................... ......................... ........................................................... .............. ............................................. C62 Tank 2.96 21 12 0.012 196.00 166.25 0.785 3.77 0.22 198.79 0.12 198.91 0.50 0.11 1.00 0.22 199.24 0.53 166.78 0.06 0 0.02 0.00 199.18 202.00 ..................... ...................................... ............................... ............... ........................... ....................... . ................................. ............................................ ................ .................... .................. .................. ......... ....... ..................... ..................... ..................... ..................... ............. ......... ......... ................ .................... ...... ..... .. .. ...... .. .. .. ... ..... ..... 0.000 2.00 0.06 .. .. .. .. ...... .. .. ... .. ... .. ..... .. NOTES: 1. All pipe material is assumed to be LCPE. 2. Flow rates (Q) are based on 100-Year Rational peak rates for a contributing area of 1.35 acres. 3. Entrance loss coefficients are from Table 4.3.1.B for LCPE pipe, headwall with square edge ' 4. Exit loss coefficients are based on Figure 4.2.1.1, Column (14) and ASCE Manual "Design ar Construction of Sanitary and Storm Sewers". 1970, page 107. Offsite Conveyance Improvements:Water Quality Tank to C68 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 20 Pipe Barrel Barrel Barrel Friction Entrance Entrance Entrance Exit Exit Outlet Inlet Inlet Approach Bend Bend Bend HW Top Pipe Se ment Q Length Size "n" Outlet Elev Inlet Elev Area Velocity Vel Head TW Elev Loss HGL Elev HL HL HL HL Cntrl. Elev Control Cntrl. Elev Vel. Head Defl. HL HL Elev. Upstream CB to CB (cfs ft (in) Value ft ft (s� f s (ft) ft (ft (ft Coef (ft) Coef (ft (ft HW/D (ft ft (de Coef ft) (ft) Structure Tank C65 2.96 20 12 0.012 195.25 204.00 0.785 3.77 0.22 197.00 0.12 197.12 0.50 0.11 1.00 0.22 197.45 1.02 205.02 0.22 20 0.12 0.03 204.82 208.17 ... ........................... .. .......... ...... ................... ................. ......................... . ..................... ..................................... ...................................................................... ............ .... ..... ................ . . .... ... .. ..... . ............. . .......... .............................................................................. ......................... ........................................................... .............. .................... ........................ CB5 C66 2.96 105 12 0.012 204.00 210.00 0.785 3.77 0.22 204.82 0.61 205.43 0.50 0.11 1.00 0.22 205.76 1.21 211.21 0.22 0 0.02 0.00 210.99 213.68 .. ................ ............................. ........................... ....................... ..................................... ........................ ............................. ..................... .................... . ............... ........................ .............................................. ............. ................................................................ ......................... ........................................................... .............. .................... ........................ CB6 C67 2.96 110 12 0.012 210.00 216.00 0.785 3.77 0.22 210.99 0.64 211.63 0.50 0.11 1.00 0.22 211.96 1.21 217.21 0.22 0 0.02 0.00 216.99 219.56 ..................... ...................... ................. ....1...... ............... .........1................ ....................... ......7....................7..... ............22...... ....21................................... ........................ .............................................. .................................................... ......................... ......................... ........................................................... .............. .................... ........................ C67 CB8 2.96 29 2 0.012 2 6.00 217.00 0. 85 3.7 0. 6.99 0.17 217.16 0.50 0.11 1.00 0.22 217.49 1.22 218.22 0.06 20 0.12 0.01 218.16 220.50 ..................... ...................... ............... ................. ............. ............... ........................... ....................... ..................................... ........................ . .................. ............... .................... .................. .................. ......... ...... ..................... ..................... ..................... ..................... ............ ......... .......... ................ .................... .. .. .. ... .. .. .. ...... .. .. .. ... ...... .. .. .. .. .. .. ...... ...... ... .. .. .. .. .. .. 0.000 2.00 0.06 7/2/2007 Wills SP HGL v1.xls Page 1 3:49 PM Appendix B. Geometry of Stormwater Tank Water Quality Tank Requirements , ��� '_ Depth=4.5' Area= 21.6 SF �_—. Depth=0.5' Tank Desi�n Tank Diameter= 6.0 FT Dead Storage Depth: 0.5 —4.5' Tank Length= 78 FT Tank Volume Provided(between depth 0.5 —4.5) = 1,685 CF Surface Area at Top of Permanent Poo1= 5.2 x 77 =406 SF Tank Requirements Volume Required=Water Quality Design Storm Volume = 1,665 CF Surface Area= 1% of Site Impervious Surfaces = 0.01 x 39,640= 396 SF ' Appendix C. Offsite Stormwater Conveyance Analysis CLEARHIS Layout Report: Layout 1 Project Precips [25 yr] 3.40 in [100 yr] 3.90 in Contributing Drainage Areas Drainage Area: A , Hyd Method: SBUH Hyd Loss Method: SCS CN Number Peak Factor: 484.00 SCS Abs: 0.20 Storm Dur: 24.00 hrs Intv: 10.00 min Area CN TC Pervious 1.9800 ac 86.00 0.33 hrs Impervious 2.9800 ac 98.00 0.10 hrs Total 4.9600 ac Supporting Data: Pervious CN Data: Pervious 86.00 1.9800 ac Impervious CN Data: Imperv. 98.00 2.9800 ac Pervious TC Data: Flow type: Description: Length: Slope: Coeff: Travel Time Sheet Sheet 150.00 ft 3.00% 0.1500 14.22 min Shallow Shallow 550.00 ft 3.60% 9.0000 5.37 min Impervious TC Data: Flow type: Description: Length: Slope: Coeff: Travel Time Sheet Sheet 150.00 ft 3.00°/a 0.0110 1.76 min Shallow Shallow 550.00 ft 3.60% 11.0000 4.39 min Drainage Area: B Hyd Method: SBUH Hyd Loss Method: SCS CN Number Peak Factor: 484.00 SCS Abs: 0.20 Storm Dur: 24.00 hrs Intv: 10.00 min Area CN TC Pervious 1.3700 ac 86.00 0.26 hrs Impervious 2.0500 ac 98.00 0.08 hrs Total 3.4200 ac Supporting Data: Pervious CN Data: Pervious 86.00 1.3700 ac Impervious CN Data: Imperv. 98.00 2.0500 ac Pervious TC Data: Flow type: Description: Length: Slope: Coeff: Travel Time Sheet Sheet 150.00 ft 5.00% 0.1500 11.88 min Shallow Shallow 420.00 ft 4.00% 9.0000 3.89 min Impervious TC Data: Flow type: Description: Length: Slope: Coeff: Travel Time Sheet Sheet 150.00 ft 5.00% 0.0110 1.47 min Shallow Shallow 420.00 ft 4.00% 11.0000 3.18 min l Drainage Area: C Hyd Method: SBUH Hyd Loss Method: SCS CN Number Peak Factor: 484.00 SCS Abs: 0.20 Storm Dur: 24.00 hrs Intv: 10.00 min Area CN TC Pervious 4.2900 ac 86.00 0.53 hrs Impervious 6.4300 ac 98.00 0.14 hrs Total 10.7200 ac Supporting Data: Pervious CN Data: Pervious 86.00 4.2900 ac Impervious CN Data: Imperv. 98.00 6.4300 ac Pervious TC Data: Flow type: Description: Length: Slope: Coeff: Travel Time Sheet Sheet 200.00 ft 1.60% 0.1500 23.59 min ' Shallow Shallow 650.00 ft 2.30% 9.0000 7.94 min � Impervious TC Data: Flow type: Description: Length: Slope: Coeff: Travel Time Sheet Sheet 50.00 ft 1.60% 0.0110 0.96 min Shallow Shallow 800.00 ft 2.60% 11.0000 7.52 min Drainage Area: D Hyd Method: SBUH Hyd Loss Method: SCS CN Number Peak Factor: 484.00 SCS Abs: 0.20 Storm Dur: 24.00 hrs Intv: 10.00 min Area CN TC Pervious 2.5400 ac 86.00 0.53 hrs Impervious 3.8000 ac 98.00 0.14 hrs Total 6.3400 ac Supporting Data: Pervious CN Data: Pervious 86.00 2.5400 ac Impervious CN Data: Imperv. 98.00 3.8000 ac Pervious TC Data: Flow type: Description: Length: Slope: Coeff: Travel Time Sheet Sheet 200.00 ft 1.60% 0.1500 23.59 min Shallow Shallow 650.00 ft 2.30% 9.0000 7.94 min Impervious TC Data: Flow type: Description: Length: Slope: Coeff: Travel Time Sheet Sheet 50.00 ft 1.60% 0.0110 0.96 min Shallow Shallow 800.00 ft 2.60% 11.0000 7.52 min Hydrograph Routing MOVEHYD [A]TO [A-25 yr]AS [25 yr] Peak Flow: 3.0341 cfs Peak Time: 8.00 hrs Hyd Vol: 48702.52 cf- 1.1181 acft MOVEHYD [B] TO [B -25 yr]AS [25 yr] Peak Flow: 2.1340 cfs Peak Time: 8.00 hrs Hyd Vol: 33562.64 cf-0.7705 acft MOVEHYD [C]TO [C -25 yr]AS [25 yr] Peak Flow: 6.1569 cfs Peak Time: 8.00 hrs Hyd Vol: 105215.77 cf-2.4154 acft MOVEHYD [D] TO [D -25 yr] AS [25 yr] Peak Flow: 3.6401 cfs Peak Time: 8.00 hrs Hyd Vol: 62214.56 cf- 1.4282 acft MOVEHYD [A] TO [A- 100 yr]AS (100 yr] Peak Flow: 3.5701 cfs Peak Time: 8.00 hrs Hyd Vol: 57298.99 cf- 1.3154 acft MOVEHYD [B] TO [B -100 yr]AS [100 yr] Peak Flow: 2.5127 cfs Peak Time: 8.00 hrs Hyd Vol: 39489.25 cf- 0.9065 acft MOVEHYD [C]TO [C -100 yr]AS [100 yr] Peak Flow: 7.2342 cfs Peak Time: 8.00 hrs Hyd Vol: 123793.84 cf-2.8419 acft MOVEHYD [D] TO [D -100 yr]AS [100 yr] Peak Flow: 4.2771 cfs Peak Time: 8.00 hrs Hyd Vol: 73201.44 cf- 1.6805 acft � v1.1 Project: Will's Short Plat Table C.1. Backwater Analysis for Shattuck Avenue S. Conveyance System Date: 07/02/07 , Shattuck Avenue -19th Street to Project Site -25-Year 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 20 Pipe Barrel Barrel Barrel Friction Entrance Entrance Entrance Exit Exit Outlet Inlet Inlet Approach Bend Bend Bend HW Top Pipe Segment Q Length Size "n" Outlet Elev Inlet Elev Area Velocity Vel Head TW Elev Loss HGL Elev HL HL HL HL Cntrl. Elev Control Cntrl. Elev Vel. Head Defl. HL HL Elev. Upstream CB to CB (cfs (ft (in) Value ft ft (s� (fps (ft ft (ft) (ft Coef (ft Coef (ft) (ft) HW/D (ft ft) (de Ccef (ft) (ft Structure CB#S1 CB#S2 11;32 49 18 0.012 140.70 141.60 1.767 6.41 0.64 146.70 0.48 147.18 0.50 0.32 1.00 0.64 148.14 1.75 144.22 0.34 0 0.02 0.01 147.80 150.50 ........... ... . .. ........................ ............... ........................... ....................... ..................................... .............................................................................................. .............................................. ............---..................................... ......................... ......................... ............................................ .....................----......................... ........................ CB#S2 CB#S3 ,8.29 .211 18 0.012 144.00 144.15 1.767 4.69 0.34 147.80 1.11 148.91 0.50 0.17 1.00 0.34 149.42 1.25 146.03 0.19 0 0.02 0.00 149.24 151.00 ...CB#........ . ...................... ............... ........................... ....................... ..................................... ..................................................................... ........................ .............................................. ............. ...................................... ......................... ......................... ............................................ ............................. .................... ........................ .S3 CB#S4 .6:16 55 18 _0:012 144:15 145;00 .1:767 3:49 0:19 149.24 0.16 149.40 0.50 0.09 1.00 0.19 149.68 0.77 146.15 0.00 0 0.02 0.00 149.68 151.50 CB#S4 .. . .. . . ... .... . ... ... . ......... . ............. ................. ................................................... .. .............. .. ........................ .. ............... .................................................. .................... ........................ . ........... .................... ........................ .. ....... . CB#S5 0.3 24 12 0.012 148.50 148.60 0.785 0.38 0.00 149.68 0.00 149.68 0.50 0.00 1.00 0.00 149.68 0.31 148.91 0.06 20 0.12 0.01 149.63 150.30 ...... ...................................... ..... . . .............. ....................... . ................................. ................. .. .................. ................ .................... .................. .................. ......... ...... .... ... ...... ..... .. .. .. .. ...... .. .. ...... ...... ................... ......................... .... .... 0.000 2.00 0.06 ............... .. .......................................................................... .................... ........................ NOTES: 1. All pipe material is assumed to be LCPE. 2. Flow rates (Q) are based on SBUH peak rates for full-buildout assumed conditions. 3. Entrance loss coefficients are from Table 4.3.1.B for LCPE pipe, headwall with square edge entrance. 4. Exit loss coefficients are based on Figure 4.2.1.1, Column (14) and ASCE Manual "Design and Construction of Sanitary and Storm Sewers". 1970, page 107. 5. Pipe rims, inverts and lengths are based on non-surveyed field and map estimates. Shattuck Avenue -19th Street to Project Site - 100-Year 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 20 Pipe Barrel Barrel Barrel Friction Entrance Entrance Entrance Exit Exit Outlet Inlet Inlet Approach Bend Bend Bend HW Top Pipe Segment Q Length Size "n" Outlet Elev Inlet Elev Area Velocity Vel Head TW Elev Loss HGL Elev HL HL HL HL Cntrl. Elev Control Cntrl. Elev Vel. Head Defl. HL HL Elev. Upstream CB to CB (cfs (ft (in) Value (ft) (ft) s (fps) (ft (ft) (ft) ft) Coef (ft) Coef (ft) (ft) HW/D (ft ft) (deg) Coef ft ( ) (ft) Structure .CB#S1 CB#S2 13.41 49 18 0.012 140.70 141.60 1.767 7.59 0.89 146.70 0.67 147.37 0.50 0.45 1.00 0.89 148.72 2.19 144.88 0.48 0 0.02 0.01 148.24 150.50 .......... ............................... ............... ........................... ....................... ..................................... ........................................................................................._... .............................................. .................................................... ......................... .......................,. .......................................................................... .................... ........................ CB#S2 CB#S3 9.84 211 18 0.012 144.00 144.15 1.767 5.57 0.48 148.24 1.56 149.81 0.50 0.24 1.00 0.48 150.53 1.49 146.39 0.26 0 0.02 0.01 15028 151.00 ..................... ...................................... ............................... ............... ........................... ....................... ..................................... ........................................................................................._... .............................................. .................................................... ......................... ......................... .......................................................................... .................... ........................ CB#S3 CB#S4 7.23 55 18 0.012 144.15 145.00 1.767 4.09 0.26 150.28 0.22 150.50 0.50 0.13 1.00 0.26 150.89 0.84 146.27 0.01 0 0.02 0.00 150.88 151.50 ........... ......................... .................... ............... ........................... ....................... ..................................... ........................ ..................................................................... .............................................. .................................................... ......................... ......................... .......................................................................... .................... ........................ CB#S4 CB#S5 ..0:5. 24 12 0.012 148.50 148.60 0.785 0.64 0.01 150.88 0.00 150.88 0.50 0.00 1.00 0.01 150.89 0.38 148.98 0.06 20 0.12 0.01 1.5C� �?4 150.30 ........ .... ................. ........................... ....................... ..................................... .............................................................................................. .............................................. .............................................................................. ......................... ........................................................................................................................ 0.000 2.00 0.06 7/2/2007 Wills SP Shattuck HGL v1.xls Page 1 5:02 PM