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HomeMy WebLinkAboutSWP272797(1) TECHNICAL INFORMATION REPORT STAFFORD CREST DIVISION-2 CITY OF RENTON, WASHINGTON GROUP FOUR JOB.497-8008 GROUP FOUR, Inc. 16030 Juanita-Woodinville Way NE Bothell, WA 98011 (206) 362-4244 • (425) 775-4581 FAX(206) 362-3819 TECHNICAL INFORMATION REPORT STAFFORD CREST DIVISION-2 RENTON, WASHINGTON 4 u4 March 8, 1999 Prepared For: Prepared By: SSHI, LLC GROUP FOUR,Inc. Contact: Bill Diamond Contact: Steve Anderson 16016-118th Place NE 16030 Juanita-Woodinville Way NE Bothell, WA 98011 Bothell, WA 98011 Phone: (425)488-2222 (206) 362-4244 • (425) 775-4581 TABLE OF CONTENTS TABLE OF CONTENTS SECTION I - Project Overview SECTION II - Preliminary Conditions Summary SECTION III - Off-Site Analysis SECTION IV- Retention/Detention Analysis and Design SECTION V- Conveyance System Analysis and Design SECTION VI - Special Reports & Studies SECTION VII -Basin and Community Plan Areas SECTION VIII- Other Permits SECTION IX- Erosion/Sedimentation Control Design SECTION X- Bond Quantities Worksheet Retention/Detention Facility Summary Sheet& Sketch Declaration of Covenant SECTION XI -Maintenance and Operations Manual APPENDIX Existing Basin Map Developed Basin Map Stafford Crest #97-8008 H SECTION I Project Overview GROUP FOUR,Inc. 16030 Juanita-Woodinville Way NE Bothell, WA 98011 Stafford Crest #97-8008 PROJECT OVERVIEW . PROJECT: Stafford Crest, Division-2 SITE AREA: 10.28 acres (9.40 acres Developed, 0.88 acres to remain undisturbed.) SITE LOCATION: The site is located on the south side of NE 36th Street between 110`h Ave SE and 1121h PL NE in the City of Renton, Washington. EXISTING LAND USE: Site vegetation consists of maple, alder and cottonwood trees and low growth vegetation. PROPOSED LAND USE: It is proposed that the site be developed with 51 single- family residences with accompanying roads and utilities. SURROUNDING LAND USE: The property is bordered on the north by NE 36th Street, on the east by the proposed plat of Stafford Crest, and on the west and south by scattered single-family residences and undeveloped land. SOILS: The on-site soils are mapped on Sheet 5 of the King County Area, Washington, Soil Survey as Alderwood gravelly sandy loam, which belongs to hydrologic soil group "C". However, this classification is not consistent with the findings of the "Preliminary Geotechnical Report"prepared by Terra Associates, Inc. dated July 10, 1997 (Project No. T-3685). Based on this report, the on-site soils are more representative of the Ragnar soil series, which is also mapped north of the site. The Ragnar soil group belongs to hydrologic soil group `B". However, per the attached 2-2-98 Memorandum from Ted Schepper, PE of Terra Associates, Inc., the on-site soils will be modeled as hydrologic soil group "C" for the analysis and design of storm water facilities. GROUP FOUR,Inc. 16030 Juanita-Woodinville Way NE Bothell, WA 98011 Stafford Crest 497-8008 PROJECT OVERVIEW Existing Drainage The subject property is located in the May Creek drainage basin. Storm water runoff from the sub-basin is overland to the west, exiting the site as sheet flow across the west side of the property as unconcentrated flow. The flow travels 350 feet before being collected by the roadside ditch of Jones Avenue. The ditch crosses under Jones by means of a concrete culvert located below the mid-point of the site. The culvert outlets to a channel that travels 100 feet and outlets to May Creek. This culvert appears to be outlet restricted and may need to be replaced or relayed. May Creek flows to the north approximately 0.5 miles and crosses under I-405. The creek reaches Lake Washington after flowing another 0.5 miles past I-405. GROUP FOUR,Inc. 16030 Juanita-Woodinville Way NE Bothell,WA 98011 Stafford Crest 497-8008 Proposed Drainage Per Core Requirement #1 of the King County Surface Water Design Manual (KCSWDM), "All surface and storm water runoff from a proposed project that proposes to construct new, or modify existing drainage facilities must be discharged at the natural location so as not to be diverted onto, or away from, the adjacent downstream property". However, no well-defined drainage system currently exists immediately downstream of the sub- basin, and discharge is currently unconcentrated. In addition, portions of the conveyance system located downstream have limited capacity, and potential for impacts to adjacent properties exists (refer to the Downstream Analysis located in Section II of this report). Therefore, to minimize potential downstream impacts, developed storm water runoff from the subject property will be discharged as described below. It is proposed that developed storm water runoff be conveyed from a detention vault located in the northwest corner of the site to an established drainage system. The proposal is to convey the developed storm water runoff from the detention vault westerly along the unopened right-of-way of NE 36"' Street. The drainage is to be conveyed in butt fused HDPP anchored at the top of the hill and down at the bottom of the hill at Jones Ave NE as shown on the Off-Site Roadway and Drainage Plan which was included as part of this submittal. Prior to the point of discharge to the natural drainage system, the flow will be dissipated in a catch basin being released to the existing roadside ditch along Jones Road. This ditch may require regrading to remove debris and vegetation up to the existing cross culvert. This culvert will also be replaced and upsized to a larger capacity culvert. Here flows from the sub-basin will combine with the natural, downstream discharge. Therefore, the proposed project will result in what can be considered minor, localized diversion of storm water run-off. Calculations will be provided to ensure the adequacy of the downstream conveyance system to convey developed storm water flows from the whole sub-basin. The downstream conveyance system will be sized to direct 100-year developed overflows safely without adverse impacts. The only proposed non-collected, by-pass area will be the area west of the buffer line off of the +40 % slopes. This area, 0.88 acres, will remain undisturbed and will not be included in the detention calculations. Frontage Improvements The frontage improvements required along NE 36"' Street are located within the City of Renton. The drainage generated from the existing and proposed improvements along 36"' drain to the May Creek basin and cam-lot be combined with the drainage from Stafford Crest Division 1 which flows to Gypsy Creek. The drainage analysis has included this frontage area which will be detained and treated in the wet vault before being released to the west in the proposed drainage system. GROUP FOUR,Inc. 16030 Juanita-Woodinville Way NE Bothell, WA 98011 FAX TERRA ASSOCIATES Inc. MEMORANDUM •• -•. Consultants in t;cotechnical Enjineerinp,Geology and Envlronmi�nral Earth Sciences To: Rob Purser Fax Number: 4SS-0295 Stafford Homes Date: 3-2-98 From: Ted Schepper, PE Project Number: 3685 Subject: Soils Hydrologic Classification Project Name: Tharp Property Renton, NNIA Rob: As discussed in our July 11, 1997 eeotechnical report, from a geologic perspective, «ve believe the soil conditions at the site would be more representative of a Ragnar soil series as opposed to an Alderwood soil as snapped by the SCS in their"Soil Survey of Kbig County". Alderwood soils are typically glacial till which is comprised of a ,veathered to unwealhered silt' sand %-ith gravel. The soils at the site are not till and were likely deposited from glacial outwash. Although from a geologic perspective the soils would not be Aldenvood, from a hydrologic perspective their permeability characteristics would be si.m-ilar particularly when consider frig a typical upper weathered glacial till zone. As discussed in our October 1 S`h, 1997 supplemental report on infiltration,the outwash soils on this site are dense and cont,-an a suflici(-nt amount of fines, which will limit their permeability. Therefore we believe it ,vould be appropriate to znal)-ze. and design storm water facilities using a hydrologic group "C" rating. We trust the infornzation presented is suffficient to meet your cuzzent needs. Should you have any questions please call. cc: Carmen Vanier Croup Four,Inc. 362-33I9 Ted Schepper, PR 12525'WIllows Road, Suite 101,Kirk1=d,washin-ton 9S0=4 Phone No.(206)S21-7777 Fw.: 321-4334 Pago 1 of 2 King County Building and Land Development Division TECHNICAL INFORMATION REPORT (TIR) WORKSHEET PART I PROJECT OWNER'AND' PROJECT ENGINEER PART 2, PROJECT LOCATION . AND DESCRIPTION Project Ownor Project Namo 57'A L7*iqOPL1 C 2CST Z)I 2 Address /60/6 —//6 7'-4 PL "F 'BaTYK& 1r?901/ Location Phone Township 21/N Project Engineer Range Sg Company_G 1U7> F0UM- iivc Section 32 Address Phone 77S—y '-2/ Project Size (0.30 " AC Upstream Drainage Basin Size 9—AC ® Subdivision DOF/G HPA Q Shoreline Management Short Subdivision Q COE 404 Q Rockory Grading = DOE Dam Safety © Structural Vaults Q Commercial Q FEMA Floodplain Other Q Other Q COE Wetlands ® HPA Community CE Drainage Basin /V14Y C/REE ACE LuASf�iVG7`� Q River 0 Stream 0 Floodplain Q Wetlands Critical Stream Roach Q Soops/Springs Deprossions/Swalos Q High GroundwatorTablo Lake Q® Steep Slopes Groundwater Recharge� Other Lakesido/Erosion Hazard Soil Ty S s Erosion Polon ial�I CTu A L. _Ti�Etiv �" G •lo� Erosive Velocities �UIyOo,Tc�.S (] Additional Shoots Attalched FIGURE 1 1/90 - Page 2 of 2 King County Bullding and Land Development Dlvlsfon TECHNICAL INFORMATION REPORT (TIR) WORKSHEET PART 8 DEVELOPMENT LIMITATIONS REFERENCE LIMITATION/SITE CONSTRAINT ® Ch,4-Downstream Ana"iL S17C $NCE-r'fGOc�S 1Ai cs7-- Ta JMtcS A vE NF a TN E N Al. /N ,Q264 p S,pi� D i-r'G 4) TNrrnl [�, u,'J11df,Q Jotio-s 4uc iN A c�LvE� 41 A y c►��c K Cl O Additional Sheets Attatched PARTS ESC REQUIREMENTS MINIMUM ESC REQUIREMENTS MINIMUM ESC REQUIREMENTS DURING CONSTRUCTION FOLLOWING CONSTRUCTION Sedimentation Facilities ® Stabilize Exposed Surface ® Stabilized Construction Entrance ® Remove and Rostore Temporary ESC Facilities ® Perimeter Runoff Control ® Clean and Remove All Silt and Debris © Clearing and Grading Restrictions ® Ensure Operation of Permanent Facilities © Cover Practices Flag Limits of NGPES © Construction Sequence Other (] Other PART 10 SURFACE WATER SYSTEM Grass Lined Channel 0 Tank = Infiltration Method of Analysis ® Pipe System ® Vault = Depression SC 0 Open Channel Energy Dissapator = Flow Dispersal Compensation/Mitigation Dry Pond 0 Wetland = Waiver of Eliminated Site Storage Wet Pond Stream = Regional Detention - �✓�.r3 Brief Description of System Operation C'okl vEY S7n K/" A L)"n f=G' in/ c uL vC,2r- SYS fd A 7�E'r�i rim�v /wA-tC—a o�aLi7, Vl�uL r- t�r_A z, �N T! �llcl G�Mn/C� . Facility Related Site Limitations Reference Facility Limitation Additional Sheets Attatched require Lax Drainage Easement © Cast in Place Vault Other [x Access Easement = Retaining Wall (� Native Growth Protection Easement ® Rockery>4'High ® Tract l� Structural on Steep Slope [� Other L or a civil engineer under my supervision have visited the site. Actual site conditions as observed were incorporated Into this workshoot and the attatchmonts. To the best of my knowledge the information provided I is accurate. Srpn.an.a 1/90 Stafford Crest #97-8008 i 29 I 28 � � I I C �� m SE 80TH ST 9 --- m N m I T I / I C fia m m s -o SI sF O� NE sool / I I NE 33RD ST N 30TH ST NF 31ST ST I I NE 27TH ST N 2 05 z 5 Q q z 13L VD 0 Z � VICINITY MAP SCALE: 1" = 1/2 MILE Figure 2 —Vicinity Map GROUP FOUR,Inc. 16030 Juanita-Woodinville Way NE Bothell, WA 98011 Stafford Crest 497-8008 SECTION II Preliminary Conditions Summary GROUP FOUR,Inc. 16030 Juanita-Woodinville Way NE Bothell, WA 98011 CITY OF RENTON DETERMINATION OF NON-SIGNIFICANCE (MITIGATED) ADVISORY NOTES APPLICATION NO(S): LUA-98-117,PP,ECF APPLICANT: Rob Purser/Stafford Construction, Inc. PROJECT NAME: Stafford Crest Preliminary Plat--Division 2 DESCRIPTION OF PROPOSAL: Applicant proposes to subdivide a 10.3 acre site into 52 parcels, suitable for detached single family residential homes. The majority of the project site is zoned R-8. A 0.72 acre portion of the site located is zoned R-1. No development is proposed for the area zoned R-1. The proposal requires environmental review, and preliminary plat approval. Location: South of NE 36th Street and 600 feet west of 112th Place SE Advisory Notes to Applicant: The following notes are supplemental information provided in conjunction with the environmental determination. Because these notes are provided as information only, they are not subject to the appeal process for environmental determinations. Police 1. Police Department estimates that the proposal would result in 38.48 calls for service annually. This is considered to have minimal impact on Renton Police. Fire Department 1. A fire hydrant with 1,000 gallons per minute (gpm) fire flow is required within 300 feet of all new single family structures. If the building square footage exceeds 3,600 s.f. in area, the minimum fire flow increases to 1,500 GPM and requires two hydrants within 300 feet of the structure. 2. A fire mitigation fee of$488.00 is required for all new single family structures. Plan Review- General 1. All plans shall conform with the Renton Drafting Standards. 2. A construction permit is required. When plans are complete, 3 copies of the drawings, two copies of the drainage report, a construction estimate, application and appropriate fee shall be submitted to the Plan Review Counter, 6th floor, Renton City Hall. 3. Temporary erosion control shall be installed and maintained o the satisfaction of the representative of the Development Services Division for the duration of the project. 4. Weekly reports on the status and condition of the erosion control plan with any recommendations of change or revision to maintenance schedules or installation shall be submitted by the project engineer of record to the Public Works Inspector. Certification of the installation and maintenance of the erosion control facilities is required prior to the recording,of the plat. 5. Installation of standard STOP signs and stoplines per MUTCD guidelines at the access driveway to NE 36th Street to safely control traffic flow/movements from the project site. 6. Surface water detention requirements for this site shall be limited for theXyear, 10-year and 100-year storm event to the pre-developed rates for those events, with a 30% safety factor for the 100-year storm event. Plan Review-Water 1. Water is provided by Coal Creek Water and Sewer District. There is an existing 8-inch diameter water main in NE 36th Street installed with the Westmont (a.k.a.: Prellwitz) Short Plat. 2. A letter of water availability is required from Coal Creek Water and Sewer Utility. Plan Review-Sanitary Sewer 1. Sanitary Sewer is provided by Coal Creek Water and Sewer Utility. Plan Review-Surface Water 1. A preliminary storm drainage plan per King County Surface Water Design standards has been submitted with the application. Few downstream drainage facilities exist, except those installed with the previous Stafford Crest plat improvements. The proposed grading plan captures all surface water on the plat and directs it to the proposed storm water system contained in the streets of the plat. All developed water is to be tightlined to an outfall identified and approved by the City of Renton. 2. The System Development Charge shall apply at the current rate of$385 per single family site. 3. A preliminary drainage report and plan was submitted in conformance with the King County Surface Water Design Manual. 4. Surface water detention requirements for this site shall be limited for the year, 10-year and 100-year storm event to the predeveloped rates for those events, with a 30% safety factor for the 100-year event. Plan Review-Transportation 1. A traffic mitigation fee of$75.00 per average daily trip at a rate of 9.55 trips per additional single family homesite shall be assessed. The fee has been estimated as $36,528.75. This fee is payable prior to the recording of the plat. 2. All frontage improvements including, but not limited to: paving, sidewalk, curb, gutter, striping, signing and lighting shall be provided to the half street minimum with a smooth transition to Lincoln Avenue NE. 3. The minimum standard for a street right-of-way dedication in a residential area is 50 feet. A variance or modification for the proposed 44-foot right-of-way including 32 feet of paving and 5 feet of sidewalk on both sides may be considered if minimum 3 foot easements are provided along the full frontage of all lots for installation of franchise utilities and street lighting . This would match the existing plat conditions. Parks Department 1. The Parks Mitigation Fee of$530.76 per single family residence applies to this proposal. Property Services 1. Property Services comments have been forwarded to the applicant and are on file in the project file. Construction Services 1. Building permit required for any retaining structures over 4-feet high. 2. The applicant's soils report recommends a 25-foot slope setback. Planning 1. The proposal is zoned R-1 and R-8. No development is proposed for the western portion of the site that is designated R-1. 2. A public hearing is required for the plat. This hearing is tentatively scheduled for December 1, 1998. 3. Project site is located in Zone 2 of the Aquifer Protection Area. Economic Development/Neighborhoods/Strategic Planning 1. The site is designated Residential Single Family (RS) and Residential Rural (RR) in the Comprehensive Plan. IT appears that all units will be contained within the RS portion. Policy LU-35 directs a minimum lot size of 4,500 s.f. in the RS designation. Proposed Lot No. 17 does not meet the minimum size standard as shown at 4,147 s.f. Stafford Crest #97-8008 SECTION III Off-Site Analysis GROUP FOUR,Inc. 16030 Juanita-Woodinville Way NE Bothell, WA 98011 Stafford Crest 497-8008 OFF-SITE ANALYSIS Upstream Tributary Area Based on inspection of Figure 3, no significant flows from upstream, off-site areas are tributary to the subject property. Downstream Analysis The subject property is located in the May Creek drainage basin. Storm water runoff from the sub-basin is overland to the west, exiting the site as sheet flow across the west side of the property as unconcentrated flow. The flow travels 350 feet before being collected by the roadside ditch of Jones Avenue. The drainage collected along the frontage of NE 36th Street is collected in a series of catch basins and discharged to a roadside ditch on the east side of 1101h PL SE. This ditch travels to the north to Lincoln Place and then follows Lincoln Place to the southwest in its southern roadside ditch. The drainages come together in the eastern roadside ditch along Jones Avenue NE. The ditch crosses under Jones by means of a 12 inch concrete culvert located below the mid-point of the site. The culvert outlets to a channel that travels 100 feet and outlets to May Creek. This culvert currently at a 0.0 % slope, appears to be outlet restricted and will need to be replaced. May Creek flows to the north approximately 0.5 miles and crosses under I-405. The creek reaches Lake Washington after flowing another 0.5 miles past 1-405. GROUP FOUR,Inc. 16030 Juanita-Woodinville Way NE Bothell,WA 98011 1 cv � LAKE WA3H1NdTON �1 OUTFALL /----_ ( ' 7 2 n S -j rtr y- 4 N 5b i�r NE 48 M—�t. - •t I'' '!1•v •th•• f '>. a �'(•^ '.'R / 's %' .s'•: !-:4.. ., .Cy'. J'.,n.'J i.'�,.." :ti,�. 1 I ire �•Ti.�., {'. �, 4%1'.n . ` _'. .. gal:[ :i..tiF ,�. � ,,•` :O `\ may:". ', : k-:-' ";k M1i/, •—__.. ,,'.__"^•• -r••-_T ...rl CEDARJ. -' D " :4�• �. -QIIAY CIE �1����:. 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'oi r" .1!�' .t ?sl; - t r o �ae�-',`cE'r'�,,, r t . vv 1 711r 3 � 1'•�, '� J, ` ry,'r :. t f f •--___ - �_�\,�11� __.,H1 ut.�1�C) .'. : t, (_ I .M�ti ?�1,�• ., . .� W,� i�lh.lii'r� V Zcl)J T^ G31 I ��• \. t,, t•.. rn Stafford Crest #97-8008 SECTION IV RID Analysis & Design GROUP FOUR,Inc. 16030 Juanita-Woodinville Way NE Bothell,WA 98011 • Stafford Crest #97-8008 R/D ANALYSIS & DESIGN Detention / Oversized Wetvault Analysis GROUP FOUR, Inc. 16030 Juanita-Woodinville Way NE Bothell, WA 98011 Stafford Crest #97-8008 R/D ANALYSIS & DESIGN PART A: Existing Site Hydrology The subject property is located in the May Creek drainage basin. The site is one drainage sub- basin and the frontage is another sub-basin both of which combine to the west in the east roadside ditch of Jones Avenue. Due to vertical constraints, i.e. steep slopes, the drainage is proposed to be carried in a 15" diameter butt-fused welded IIDPP. This pipe is to be installed on the surface so as not to disturb the steep slopes any more than necessary. The pipe is sized to convey the developed 100- year/24-hour storm event. At the point of discharge there will be a dissipation structure which will outlet to the roadside ditch along Jones Avenue. The total site area is 10.28 acres and the off-site frontage area is 0.46 acres. Per the attached 2-2- 98 memorandum from Ted Schepper, PE of Terra Associates, Inc., the on-site soils will be modeled as hydrologic soil group C for the analysis and design of the storm water facilities. The existing land use is second growth wooded or brush. This corresponds to an existing curve number of 81. GROUP FOUR,Inc. 16030 Juanita-Woodinville Way NE Bothell, WA 98011 3/19/99 GROUP FOUR, Inc. page 1 STAFFORD CREST DIVISION 2 WETVAULT DOE R/D ANALYSIS BASIN SUMMARY BASIN ID: 100X NAME : STAFFORD CREST-2 100-YEAR EX SCS METHODOLOGY TOTAL AREA. . . . . . . : 9 . 86 Acres BASEFLOWS : 0 . 00 cfs RAINFALL TYPE . . . . : TYPElA PERVIOUS AREA PRECIPITATION. . . . : 3 . 90 inches AREA. . : 9 . 57 Acres TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 81 . 00 TIME OF CONC. . . . . : 41 . 11 min IMPERVIOUS AREA ABSTRACTION COEFF: 0 . 20 AREA. . : 0 . 29 Acres CN. . . . . 98 . 00 PEAK RATE : 3 . 63 cfs VOL: 1 . 65 Ac-ft TIME : 520 min BASIN ID: 1OX NAME : STAFFORD CREST-2 10-YEAR EXIST SCS METHODOLOGY TOTAL AREA. . . . . . . : 9 . 86 Acres BASEFLOWS : 0 . 00 cfs RAINFALL TYPE. . . . : TYPElA PERVIOUS AREA PRECIPITATION. . . . : 2 . 90 inches AREA. . : 9 . 57 Acres TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 81 . 00 TIME OF CONC. . . . . : 41 . 11 min IMPERVIOUS AREA ABSTRACTION COEFF: 0 . 20 AREA. . : 0 . 29 Acres CN. . . . . 98 . 00 PEAK RATE : 2 . 00 cfs VOL: 1 . 01 Ac-ft TIME : 520 min BASIN ID: 2X- . 5 NAME: STAFFORD CREST-2 0 . 5-2YEAR EX SCS METHODOLOGY TOTAL AREA. . . . . . . : 4 . 93 Acres BASEFLOWS : 0 . 00 cfs RAINFALL TYPE . . . . : TYPElA PERVIOUS AREA PRECIPITATION. . . . : 2 . 00 inches AREA. . : 4 . 79 Acres TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 81 . 00 TIME OF CONC. . . . . : 41 . 11 min IMPERVIOUS AREA ABSTRACTION COEFF : 0 . 20 AREA. . : 0 . 14 Acres CN. . . . . 98 . 00 PEAK RATE : 0 . 38 cfs VOL: 0 . 25 Ac-ft TIME: 530 min 3/19/99 GROUP FOUR, Inc . page 1 STAFFORD CREST DIVISION 2 WETVAULT DOE R/D ANALYSIS BASIN SUMMARY BASIN ID: 2X NAME: STAFFORD CREST-2 2-YEAR EXIST SCS METHODOLOGY TOTAL AREA. . . . . . . : 9 . 86 Acres BASEFLOWS : 0 . 00 cfs RAINFALL TYPE. . . . : TYPEIA PERVIOUS AREA PRECIPITATION. . . . : 2 . 00 inches AREA. . : 9 . 57 Acres TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 81 . 00 TIME OF CONC. . . . . : 41 . 11 min IMPERVIOUS AREA ABSTRACTION COEFF: 0 . 20 AREA. . : 0 . 29 Acres CN. . . . . 98 . 00 TcReach - Sheet L: 300 . 00 ns : 0 . 4000 p2yr: 2 . 00 s : 0 . 0750 TcReach - Shallow L: 210 . 00 ks : 5 . 00 s : 0 . 0750 PEAK RATE : 0 . 76 cfs VOL: 0 . 50 Ac-ft TIME: 530 min Stafford Crest 997-8008 R/D ANALYSIS & DESIGN PART B: Developed Site Hydrology It is proposed that the 10.28 acre site be developed with 51 single family residences. Per Table 3.5.2B of the King County Surface Water Design Manual, the percent impervious area is calculated below. Existing Site Conditions Developed Site Area ...........9.40 acres Undisturbed Area . .0.88 acres Total Site Area 10.28 acres Off-site Frontage.. .0.46 acres Total Contributing Area.......9.86 acres CN = 81 for 9.86 acres, 0.88 acres to be allowed to continue to sheet flow off in an undisturbed state. Time of Concentration =41.11 minutes Sheet flow for 300' @ 7.50 %w/ns: 0.40, = 38.55 min Shallow flow for 210' @ 7.50 %w/ks: 5.00, =2.56 min Developed Site Conditions Proposed Lots= 51 51 dwelling units/ 9.40acres= 5.43 DU/GA relates to 50 % impervious Impervious area= (0.50) x(9.40)+ 0.46 (off-site)= 5.16 acres CN = 98 Pervious area= 9.40—4.70 =4.70 acres CN= 86 Developed time of concentration=27.02 minutes Sheet flow for 160' @ 1.0% w/ns: 0.15, = 23.82 min Channel flow for 1140' @ 2.0 %w/kc: 42.00, = 3.20 min Precipitation Pz= 2.0" P,o=2.9" P100=3.9" GROUP FOUR,Inc. 16030 Juanita-Woodinville Way NE Bothell,WA 98011 3/ 8/99 GROUP FOUR, Inc . page 1 STAFFORD CREST DIVISION 2 WETVAULT R/D ANALYSIS --------------------------------------------------------------------- BASIN SUMMARY BASIN ID: 100D NAME : STAFFORD CREST-2 100-YEAR DEV SCS METHODOLOGY TOTAL AREA. . . . . . . : 9 . 86 Acres BASEFLOWS : 0 . 00 cfs RAINFALL TYPE. . . . : TYPEIA PERVIOUS AREA PRECIPITATION. . . . : 3 . 90 inches AREA. . : 4 . 70 Acres TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 86 . 00 TIME OF CONC. . . . . : 27 . 02 min IMPERVIOUS AREA ABSTRACTION COEFF : 0 . 20 AREA. . : 5 . 16 Acres CN. . . . . 98 . 00 PEAK RATE : 6 . 69 cfs VOL: 2 .43 Ac-ft TIME: 510 min BASIN ID: 10D NAME: STAFFORD CREST-2 10-YEAR DEV SCS METHODOLOGY TOTAL AREA. . . . . . . : 9 . 86 Acres BASEFLOWS : 0 . 00 cfs RAINFALL TYPE. . . . : TYPEIA PERVIOUS AREA PRECIPITATION. . . . : 2 . 90 inches AREA. . : 4 . 70 Acres TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 86 . 00 TIME OF CONC. . . . . : 27 . 02 min IMPERVIOUS AREA ABSTRACTION COEFF: 0 . 20 AREA. . : 5 . 16 Acres CN. . . . . 98 . 00 PEAK RATE: 4 . 53 cfs VOL: 1 . 66 Ac-ft TIME: 510 min BASIN ID: 2D NAME : STAFFORD CREST-2 2-YEAR DEV SCS METHODOLOGY TOTAL AREA. . . . . . . : 9 . 86 Acres BASEFLOWS : 0 . 00 cfs RAINFALL TYPE. . . . : TYPEIA PERVIOUS AREA PRECIPITATION. . . . : 2 . 00 inches AREA. . : 4 . 70 Acres TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 86 . 00 TIME OF CONC. . . . . : 27 . 02 min IMPERVIOUS AREA ABSTRACTION COEFF: 0 . 20 AREA. . : 5 . 16 Acres CN. . . . . 98 . 00 TcReach - Sheet L: 160 . 00 ns : 0 . 1500 p2yr: 2 . 00 s : 0 . 0100 TcReach - Channel L: 1140 . 00 kc :42 . 00 s : 0 . 0200 PEAK RATE: 2 . 62 cfs VOL: 1 . 00 Ac-ft TIME: 510 min Stafford Crest #97-8008 R/D ANALYSIS & DESIGN PART C: Hydrologic Analysis Proposed stormwater detention facilities will be designed in conformance with the Department of Ecology Storm Water Management Manual for the Puget Sound Basin (DOE Manual), and the City of Renton. Therefore, in conforming to both Ecology and City criteria, it has been determined that the post-developed peak rate of runoff from the subject property will be the 2-, 10- and 100-year/24-hour design storms. The requirements of the City of Renton are to release at the existing predeveloped 2, 10 and 100 year/24 hour storm rates and add a 30% factor of safety will be applied to the required design volume, as required in the KCSWDM. The applicant is applying for a HPA and therefore the detention release rates are designed at half the 2, the 10 and the 100 year/24 hour with a 20 % correction factor per the DOE manual. Therefore, by meeting DOE's requirements the proposed wet vault design is in excess of the City's requirements by approximately 30 %. Since more than 1.0 acres of impervious surfaces subject to vehicular use is proposed, and a Type 2 stream is located within one mile of the project site, the site is subject to Special Requirement #5, as outlined in Section 1.3.5 of the KCSWDM. To meet the requirements of Special Requirement #5, and to eliminate the need for a biofiltration swale, an "oversized" wetvault is proposed. The design water surface area of the wetvault will be equal to or greater than 1.50 percent of the total impervious surfaces subject to vehicular use. The design volume of the wetvault will be equal to the total volume of runoff from the tributary sub-basin proposed developed conditions using a water quality design storm event having a total precipitation, Pt-wq, where Pt-wq is one- third of the 2-year/24-hour total precipitation. The resulting design volume will be increased by a factor of 50 percent as required by the City of Renton. The required computations will be performed using the Soil Conservation Service Unit Hydrograph (SCSUH) method with Type IA rainfall distribution and 24-hour design storm durations. The computer program "WaterWorks Version 3.1" will be used to develop and manipulate hydrographs, and perform the required level pool routing. No significant upstream, off-site flows are tributary to the subject property. The release rate from the proposed detention facility was not adjusted as they are no bypass flows. The "Steep Slopes" (+40%) and buffer areas will remain undisturbed. These areas will continue to be allowed to sheet flow offsite to the west and not be accounted for as by- pass volume. GROUP roux,Inc. 16030 Juanita-Woodinville Way NE Bothell, WA 98011 Stafford Crest 497-8008 R/D ANALYSIS & DESIGN PART D: R/D System Attached are the calculations, equations, references, storage/volume tables, graphs and other information used to determine the storage facility volumes. The attached calculations are provided in the form of"Waterworks Version 3.1" computer generated output. The attached Tables and Figures are taken from the KCSWDM. GROUP FOUR,Inc. 16030 Juanita-Woodinville Way NE Bothell,WA 98011 3/19/99 GROUP FOUR, Inc . page 1 STAFFORD CREST DIVISION 2 WETVAULT DOE R/D ANALYSIS --------------------------------------------------------------------- --------------------------------------------------------------------- HYDROGRAPH SUMMARY PEAK TIME VOLUME HYD RUNOFF OF OF Contrib NUM RATE PEAK HYDRO Area cfs min. cf\AcFt Acres --------------------------------------------- --------------------------------------------- 1 0 . 756 530 21569 cf 9 . 86 z-YR Ex. 2 2 . 618 510 43601 cf 9 . 86 z -vR 4eV 3 1 . 998 520 43823 cf 9 . 86 /o-yr f-x. 4 4 . 530 510 72497 cf 9 . 86 /o-yR b4V 5 3 . 634 520 71890 cf 9 . 86 /as-yR. Ex 6 6 . 695 510 105748 cf 9 . 86 /ev-YR DE%/ 7 0 . 378 530 10785 cf 4 . 93— %z.-7- YR 6X. 11 0 . 375 1450 42333 cf 9 . 86 = -yR Rl�LEAJG 12 1 . 319 650 71019 cf 9 . 8 6 RELF-Aye 13 3 . 603 560 104196 cf 9 . 86/44-YR R64EAS(e 3/19/99 GROUP FOUR, Inc . page 5 STAFFORD CREST DIVISION 2 WETVAULT DOE R/D ANALYSIS LEVEL POOL TABLE SUMMARY MATCH INFLOW -STO- -DIS- <-PEAK-> STORAGE <--------DESCRIPTION---------> (cfs) (cfs) --id- --id- <-STAGE> id VOL (cf) 2-YEAR ...... ................. 0.38 2.62 V2 C3 205.65 11 22619.19 cf 10-YEAR ...................... 2.00 4.53 V2 C3 206.19 12 25154.47 cf - 100-YEAR ..... ................ 3.63 6.69 V2 C3 206.99 13 28832.07 cf --�ES/G N Vo LUv1'tE W/ Zo / C4RR.ECt76r1 FACT A- => A2 x 7-Q832 = 3I/J5.Q8 cl:t- RcQ�d VatuinE Votuw,.E. PtuvjDeh = '7Sk'7q x 6.25 3 %4 87 cF 3/19/99 GROUP FOUR, Inc . page 2 STAFFORD CREST DIVISION 2 WETVAULT DOE R/D ANALYSIS -------------------- STAGE STORAGE TABLE RECTANGULAR VAULT ID No . V2 Description: Length: 70 . 00 ft . Width: 66 . 00 ft . STAGE <----STORAGE----> STAGE <----STORAGE----> STAGE <----STORAGE----> STAGE <----STORAGE----> (ft) ---cf--- --Ac-Ft- (ft) ---cf--- --Ac-Ft- (ft) ---cf--- --AC-Ft- (ft) ---cf--- --Ac-Ft- 200.75 0.0000 0.0000 202.60 8547 0.1962 204.50 17325 0.3977 206.40 26103 0.5992 200.80 231.00 0.0053 202.70 9009 0.2068 204.60 17787 0.4083 206.50 26565 0.6098 200.90 693.00 0.0159 202.80 9471 0.2174 204.70 18249 0.4189 206.60 27027 0.6205 201.00 1155 0.0265 202.90 9933 0.2280 204.80 18711 0.4295 206.70 27489 0.6311 201.10 1617 0.0371 203.00 10395 0.2386 204.90 19173 0.4402 206.80 27951 0.6417 201.20 2079 0.0477 203.10 10857 0.2492 205.00 19635 0.4508 206.90 28413 0.6523 201.30 2541 0.0583 203.20 11319 0.2598 205.10 20097 0.4614 207.00/00 28875 0.6629 201.40 3003 0.0689 203.30 11781 0.2705 205.20 20559 0.4720 207.10 29337 0.6735 201.50 3465 0.0795 203.40 12243 0.2811 205.30 21021 0.4826 207.20 29799 0.6841 201.60 3927 0.0902 203.50 12705 0.2917 205.40 21483 0.4932 207.30 30261 0.6947 201.70 4389 0.1008 203.60 13167 0.3023 205.50 21945 0.5038 207.40 30723 0.7053 201.80 4851 0.1114 203.70 13629 0.3129 205.60 S 22407 0.5144 207.50 31185 0.7159 201.90 5313 0.1220 203.80 14091 0.3235 205.70 22869 0.5250 207.60 31647 0.7265 202.00 5775 0.1326 203.90 14553 0.3341 205.80 23331 0.5356 207.70 32109 0.7371 202.10 6237 0.1432 204.00 15015 0.3447 205.90 23793 0.5462 207.80 32571 0.7477 202.20 6699 0.1538 204.10 15477 0.3553 206.00 24255 0.5568 207.90 33033 0.7583 202.30 7161 0.1644 204.20 15939 0.3659 206.10 24717 0.5674 208.00 33495 0.7689 202.40 7623 0.1750 204.30 16401 0.3765 206.2010 25179 0.5780 202.50 8085 0.1856 204.40 16863 0.3871 206.30 25641 0.5886 1/&Z-7- w/o 10% CQRAQ-c i6 J rXCa2 3/19/99 GROUP FOUR, Inc . page 3 STAFFORD CREST DIVISION 2 WETVAULT DOE R/D ANALYSIS STAGE STORAGE TABLE RECTANGULAR VAULT ID No. V2-20 Description: STAFFORD CREST DIV 2 @ 120 0 Length: 75 . 00 ft . Width: 74 . 00 ft . STAGE <----STORAGE----> STAGE <----STORAGE----> STAGE <----STORAGE----> STAGE <----STORAGE----> (ft) ---cf--- --Ac-Ft- (ft) ---cf--- --Ac-Ft- (ft) ---cf--- --AC-Ft- (ft) ---cf--- --Ac-Ft- 200.75 0.0000 0.0000 202.60 10268 0.2357 204.50 20813 0.4778 206.40 31358 0.7199 200.80 277.50 0.0064 202.70 10823 0.2485 204.60 21368 0.4905 206.50 31913 0.7326 200.90 832.50 0.0191 202.80 11378 0.2612 204.70 21923 0.5033 206.60 32468 0.7454 201.00 1388 0.0319 202.90 11933 0.2739 204.80 22478 0.5160 206.70 33023 0.7581 201.10 1943 0.0446 203.00 12488 0.2867 204.90 23033 0.5288 206.80 33578 0.7708 201.20 2498 0.0573 203.10 13043 0.2994 205.00 23588 0.5415 206.90 34133 0.7836 201.30 3053 0.0701 203.20 13598 0.3122 205.10 24143 0.5542 207.00196 34688 0.7963 201.40 3608 0.0828 203.30 14153 0.3249 205.20 24698 0.5670 207.10 35243 0.8091 201.50 4163 0.0956 203.40 14708 0.3376 205.30 25253 0.5797 207.20 35798 0.8218 201.60 4718 0.1083 203.50 15263 0.3504 205.40 25808 0.5925 207.30 36353 0.8345 201.70 5273 0.1210 203.60 15818 0.3631 205.50 26363 0.6052 207.40 36908 0.8473 201.80 5828 0.1338 203.70 16373 0.3759 205.60 2 26918 0.6179 207.50 37463 0.8600 201.90 6383 0.1465 203.80 16928 0.3886 205.70 27473 0.6307 207.60 38018 0.8728 202.00 6938 0.1593 203.90 17483 0.4013 205.80 28028 0.6434- 207.70 38573 0.8855 202.10 7493 0.1720 204.00 18038 0.4141 205.90 28583 0.6562 207.80 39128 0.8982 202.20 8048 0.1847 204.10 18593 0.4268 206.00 29138 0.6689 207.90 39683 0.9110 202.30 8603 0.1975 204.20 19148 0.4396 206.10 29693 0.6816 208.00 40238 0.9237 202.40 9158 0.2102 204.30 19703 0.4523 206.2010 30248 0.6944 202.50 9713 0.2230 204.40 20258 0.4650 206.30 30803 0.7071 VA 1JUr w/ 2� % Co226c"1"��n1 �i�c7-aR 3/19/99 GROUP FOUR, Inc . page 2 STAFFORD CREST DIVISION 2 WETVAULT DOE R/D ANALYSIS STAGE DISCHARGE TABLE COMBINATION DISCHARGE ID No. C3 Description: Structure : 04 Structure : Structure : N3 Structure : Structure : STAGE <--DISCHARGE---> STAGE <--DISCHARGE---> STAGE <--DISCHARGE---> STAGE <--DISCHARGE---> (ft) ---cfs-- ------- (ft) ---cfs-- ------- (ft) ---cfs-- ------- (ft) ---cfs-- ------- 200.75 0.0000 202.60 0.2307 204.50 0.3284 206.40 1.8849 200.80 0.0379 202.70 0.2368 204.60 0.3328 206,50 2.1738 200.90 0.0657 202.80 0.2428 204.70 0.3371 206.60 2.4670 201.00 0.0848 202.90 0.2487 204.80 0.3413 206.70 2.7617 201.10 0.1003 203.00 0.2544 204.90 0.3455 206.80 3.0552 201.20 0.1138 203.10 0.2600 205.00 0.3497 206.90 3.3453 201.30 0.1258 203.20 0.2655 205.10 0.3537 207.00 3.6299 /Q a, 201.40 0.1367 203.30 0.2708 205.20 0.3578 207.10 3.9069 1 201.50 0.1469 203.40 0.2761 205.30 0.3618 207.20 4.1744 201.60 0.1564 203.50 0.2813 205.40 0.3657 207.30 4.4307 201.70 0.1653 203.60 0.2863 205.50 0.3696 207.40 4.6740 201.80 0.1738 203.70 0.2913 205.60 0.3735 _ 207.50 4.9026 201.90 0.1819 203.80 0.2962 205.70 0.3774J 'I V'e 207.60 5.1151 202.00 0.1896 203.90 0.3010 205.80 0.4724 207.70 5.3098 202.10 0.1971 204.00 0.3058 205.90 0.6377 207.80 5.4852 202.20 0.2042 204.10 0.3104 206.00 0.8434 207.90 5.6400 202.30 0.2112 204.20 0.3150 206.10 1.0776 208.00 5.7727 202.40 0.2179 204.30 0.3196 206.20 1.3328 +YR 202.50 0.2244 204.40 0.3240 206.30 1.6033 3/19/99 GROUP FOUR, Inc . page 4 STAFFORD CREST DIVISION 2 WETVAULT DOE R/D ANALYSIS STAGE DISCHARGE TABLE MULTIPLE ORIFICE ID No. 04 Description: Outlet Elev: 200 . 75 Elev: 198 . 75 ft Orifice Diameter : 2 . 5000 in. STAGE <--DISCHARGE---> STAGE <--DISCHARGE---> STAGE <--DISCHARGE---> STAGE <--DISCHARGE---> (ft) ---cfs-- ------- (ft) ---cfs-- ------- (ft) ---cfs-- ------- (ft) ---cfS-- ------- 200.75 0.0000 202.60 0.2307 204.50 0.3284 206.40 0.4031 200.80 0.0379 202.70 0.2368 204.60 0.3328 206.50 0.4067 200.90 0.0657 202.80 0.2428 204.70 0.3371 206.60 0.4102 201.00 0.0848 202.90 0.2487 204.80 0.3413 206.70 0.4137 201.10 0.1003 203.00 0.2544 204.90 0.3455 206.80 0.4172 201.20 0.1138 203.10 0.2600 205.00 0.3497 206.90 0.4206 201.30 0.1258 203.20 0.2655 205.10 0.3537 207.00 0.4240 201.40 0.1367 203.30 0.2708 205.20 0.3578 207.10 0.4274 201.50 0.1469 203.40 0.2761 205.30 0.3618 207.20 0.4307 201.60 0.1564 203.50 0.2813 205.40 0.3657 207.30 0.4341 201.70 0.1653 203.60 0.2863 205.50 0.3696 207.40 0.4374 201.80 0.1738 203.70 0.2913 205.60 0.3735 207.50 0.4407 201.90 0.1819 203.80 0.2962 205.70 0.3774 207.60 0.4439 202.00 0.1896 203.90 0.3010 205.80 0.3811 207.70 0.4471 202.10 0.1971 204.00 0.3058 205.90 0.3849 207.80 0.4503 202.20 0.2042 204.10 0.3104 206.00 0.3886 207.90 0.4535 202.30 0.2112 204.20 0.3150 206.10 0.3923 208.00 0.4567 202.40 0.2179 204.30 0.3196 206.20 0.3959 202.50 0.2244 204.40 0.3240 206.30 0.3996 3/19/99 GROUP FOUR, Inc . page 3 STAFFORD CREST DIVISION 2 WETVAULT DOE R/D ANALYSIS --------------------------------------------------------------------- --------------------------------------------------------------------- STAGE DISCHARGE TABLE NOTCH WEIR ID No. N3 Description: Weir Length: 0 . 9000 ft . Weir height (p) : 4 . 7500 ft . Elevation : 205 . 70 ft . Weir Increm: 0 . 10 STAGE <--DISCHARGE---> STAGE <--DISCHARGE---> STAGE <--DISCHARGE---> STAGE <--DISCHARGE---> (ft) ---CfS-- ------- (ft) ---CfS-- ------- (ft) ---CfS-- ------- (ft) ---CfS-- ------- 205.70 0.0000 206.30 1.2037 206.90 2.9247 207.50 4.4620 205.80 0.0912 206.40 1.4817 207.00 3.2059 207.60 4.6712 205.90 0.2528 206.50 1.7671 207.10 3.4795 207.70 4.8627 206.00 0.4548 206.60 2.0568 207.20 3.7437 207.80 5.0349 206.10 0.6853 206.70 2.3479 207.30 3.9966 207.90 5.1865 206.20 0.9368 206.80 2.6380 207.40 4.2366 208.00 5.3160 Stafford Crest #97-8008 Design Water Surface Area Impervious Surface Subject to Vehicular Use = 1.38 acres Water Surface Area Required= (1.50 %) x (1.38) = 902 square feet Water Surface Area Proposed = 75' x 74' = 5,550 square feet Water Qualily Design Volumc (Dead Storage) Design Volume Required = (150 %) x (6-month storm volume) = (1.5) x (0.1487 Ac-ft) x (43,560 ft/Ac) = 9716 cubic feet (1.75' depth proposed) x (5,550 sf) + 1.0' x 3.141 x 2.25 x 2.25 = 9,728 cubic feet GROUP FOUR,Mc. 16030 Juanita-Woodinville Way NE Bothell,WA 98011 3/ 9/99 GROUP FOUR, Inc . page 1 STAFFORD CREST DIVISION 2 WETVAULT R/D ANALYSIS --------------------------------------------------------------------- BASIN SUMMARY BASIN ID: WQ NAME : STAFFORD CREST-2 WATER QUALITY SCS METHODOLOGY TOTAL AREA. . . . . . . : 9 . 86 Acres BASEFLOWS : 0 . 00 cfs RAINFALL TYPE. . . . : TYPElA PERVIOUS AREA y3 Z YR. PRECIPITATION. . . . : 0 . 67 inches AREA. . : 4 . 70 Acres TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 86 . 00 TIME OF CONC. . . . . : 27 . 02 min IMPERVIOUS AREA ABSTRACTION COEFF: 0 . 20 AREA. . : 5 . 16 Acres CN. . . . . 98 . 00 PEAK RATE: 0 . 22 cfs VOL: 0 . 15 Ac-ft TIME : 520 min . . � . �l►i_ .��, fir/ � . all FAR n ONE wI"FIRM wirl J 1 ;mg gil I •�A� ,Y A PF MA Few MMW mot- � ,�;.•n� � �. ■ i Via• � �r� . .� a MCI i �' �� � -'� 'fir � ; ��•��� �� r Stafford Crest #97-8008 �rw.: +,F1+aK*l�;i li'••Pleasure+,e tV{�n g �� , ,••' ' t�; �, '• '/' ``yr�*•,�'1y !� IPofnt',2i i• 'a'9�,j I 5 i ■.. r:rt r •'p11t�yti.. •� �y+�,t Tlll\t{rr rt- Jl.f •'ztl r`rti v� r • /"'} 1 I t ' ,i 1 1 $ 'Yr •' Fj x•yr, I ytl, , r?�t„4:r tPC • 1'� i ( r.,r AmC� r { r•t 1` P Wt4 ��G' • rq• � Irt rti Ur •/1 % • ' \mB rr �• j y�fvrt i krt)a�, It4iy •r• ,+ I ! / tt ry az ; r+ t n�rld:' A rl' � t • • �•• ,•�• I�Y� 4f i. •�r �� , ,� / d� 1� ;y r •lrt j Al'Irr`I �!-IOC •1 •'i t,�Ri•• 'l ,r , ' '�r�y • r r ' %.T 1 i y 1 A• t' 4• • rt. , r{ f I ;+4 rl ii y `y1 I . Bhp d,,\ •t '.-1 •i r h 4 I ; »tli, 6 A B�N r 29 ';1 t g r +R rn 7;.ABC �� T IA�''�1l'3�,.,� -'• ' iw ��' Kp B'• 1 r\ - •Y.1 r Ay w t :l�.,liW�� Ke1.�Y�•+'' 1�+/ � r ,r r •1 . y. +,Il. •pin >i. '.,;;r tr(. t -J ,E Cw •f.,i:r _ t t t ., , , r , ./,, P ^�.I. r;,,' L..Hills . In »\y�.yy. .i9 'r •+��: + ,,r rly . x, • W AmC 4 � + i ty,r its tt s _ t t.,i i •KpD 7k p.iY � . s• t �' . �7ri3 •�i � ,` �}�ili;�'t,.17tr+ .^, t , �t �yt~i� y 1�i M .. � y �b ,r. •^''• M1I �.. ,arc i :',� ,. AgD,,,. 3 f'r' f•,. Bm pD AmC`;.t 1� At `}�yvJ•. ,fir .?11�� AgC fit'' ,1 ABC 11 \\ I .r KpC,li'1Ay �. Y�. y .EvC y9M .109 .+ rr ey is ),r • i�� O ov0 r.:. ,9�0•\ I j B \` Agp —_ • r r ti , ti+ T 1 ,1 i� t -(F �•t�t"L y,t R..A, ■ )• ; � O .,1 r ��• ABC •� - r No - Z 1` BMA My�. tJ ytf? ytat)aS,.1r{ tyt�r y SC a ( '' 605 •q, P.J .kf. I ti .. �• YI __ �• ..t . _:i; . •" •: rA6C y+t,+r ! F'"i i; t t ti•_ bl, '. AP,C _ �• t 'A •T •1 •yr Ago MBD ;� 3i{ 1 ^ t tt �lry 'a t Cry,Fx r'.r d rye+, F r+ IL++M r • c° 1 � ' r i�•� \ !�'s�•il' i. D A Cyr •y a •'SF st '4•ly ennydale I t, _ !' _ ,1• : +faU`I.{r^ t`ai lrtiir�ttt�Yi..� 'lOC AkF" I AkF Ev8 ,iA,' i`. A Ag m.'i:�. 7: •1 GRAVEL Coleman Poln Q •j Y PIT ,v Sr tf ,lt 4. '• • • r": AkF •r,l �� •. �•• r rr�: y 1.•tt ti� !i y. �InA• — �•.-'.t'" �_ �. •_r.• _._.j. .. y •a, 319 live ; r Y F� 1 t1 •�'+(1 .,tn 14- B / ; I •—^ _ '�,:1+ v BM 411 4 it a{r r4 C BM'ASD z 303r a u. ~ <t1Yii ol:i°'tlt ,j' } + n , y.l , , u '� t9 y �lrip1 t Y• �, t� •\� 1 z A +N Evp lr 1 r—_ � i�ia•`rti+i+,1 fN a r \�Jr7�Ij �r CQti ?' I �. 'i`•' EvC •'',�ASC ltX it. � � i1Y�i. y fit + i '•t :ti.t ;kl, �tr r. ;r• . � �'� t b- '� v i t'�T+• �i ••A,• �{�� t.; ., '.a�t1 ry tn. AkF 1 ,c ! A.i� �� t✓�r., ��;r�a�1 Q it •�• �.;� lr�Si•; .l — 0_T;, a• ,. i "� •,'� ++�.. .AmC ar •• .I �. •,�J• ..•c..it..A.:Rn"'C:y ��. �•: )' '` .�'L.• �-t •r:.r. �� T.� "1 - . >,:1Ji•.4`. r �. Figure 4—SCS Soils Map Scale 1"=2000' GROUP FOUR,Inc. 16030 Juanita-Woodinville Way NE Bothell,WA 98011 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL (2) CN alues can be area w�ighted when they'applyyto pervious ar eas of similar CN's (within 20 ., CN points). However, high CN areas should not be combined with low CN areas (unless the low CN areas are less than 15% of the subbasin). In this case, separate hydrographs should be generated and summed to form one hydrograph. FIGURE 3.5.2A HYDROLOGIC SOIL GROUP OF THE SOILS INKING COUNTY HYDROLOGIC HYDROLOGIC SOIL GROUP GROUP* SOIL GROUP GROUP* Alderwood C Orcas Peat D Arents, Aldenvood Material C Oridia D Arents, Everett Material B Ovall C Beausite C Pilchuck C Bellingham D Puget D Briscot D Puyallup B SEE Buckley D Ragnar g Coastal Beaches Variable Henlon D FATe:CM Earlmont Silt Loam D Riverwash Variable Edgewick C Salal C Everett A/B `Sammamish D Indianola A Seattle D Kitsap C Shacar D Klaus C Si Silt C Mixed Alluvial Land Variable Snohomish D Neilton A Sultan C Newberg B Tukwila D Nooksack C Urban Variable Normal Sandy Loam D Woodinville D HYDROLOGIC SOIL GROUP CLASSIFICATIONS A. (Low runoff potential). Soils having high infiltration rates, even when thoroughly wetted, and consisting chiefly of deep, welt-to-excessively drained sands or gravels. These soils have a high rate of water transmission. B. (Moderately low runoff potential). Soils having moderate infiltration rates when thoroughly wetted, and consisting chiefly of moderately fine to moderately coarse textures. These soils have a moderate rate of water transmission. OC (Moderately high runoff potentiai). Soils having slow infiltration rates when thoroughly wetted, and consisting chiefly of soils with a layer that impedes downward movement of water, or soils with moderately fine to fine textures. These soils have a slow rate of water transmission. D. (High runoff potential). Soils having very slow infiltration rates when thoroughly wetted and consisting chiefly of clay soils with a high swelling potential, soils with a permanent high water table, soils with a hardpan or clay layer at or near the surface, and shallow soils over nearly impervious materW. These soils have a very slow rate of water transmission. * From SCS, TR-55, Second Edition, June 1986, Exhibit A-1. Revisions made from SCS, Soil Interpretation Record, Form #5, September 1988. 3.5.2-2 11/92 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 SOIL 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 II1 86 Orchard: with cover crop 81 88 92 94 Open spaces, lawns, parks, golf courses, cemeteries, landscaping. Good condition: grass cover on t75% of the 68 80 II6 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 98 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. DU/GA 15 shall be selected for 2..5 DU/GA 20 pervious & impervious 2.5 DU/GA 30 DU/GA 25 portions of the site 3.0 DU/GA 34 or basin 3.5 DU/GA 38 4.0 DU/GA 42 4.5 DU/GA 46 5.0 DU/GA 48 .5 DU/GAE--S 43 `'-' 50..E-.._. 50.0YO 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(3) The remaining pervious areas (lawn) are considered to be in good system. condition for these curve numbers. III-1-12 FEBRUARY, 1992 Stafford Crest 997-8008 R/D ANALYSIS & DESIGN 100yr Overflow Analysis (Detention Vault—CB #1) GROUP FOUR,Inc. 16030 Juanita-Woodinville Way NE Bothell, WA 98011 Stafford Crest #97-8008 100yr Overflow Analysis (Detention Vault—CB #1) Flows from Stafford Crest Division 2 and the frontage road NE 36' Street will account for the full development of the tributary area to the HDPE drainage system west down the NE 36' Street ROW. The tributary area is 9.86 acres and the undetained flow for the 100-year/24-hour storm event amounts to 6.7 cfs. A 15 inch diameter pipe was analyzed for its carrying capacity and found to handle 6.97 cfs at a 1.0 % slope. The headwater depth relationship (HW/D) at the entrance to the 15 " diameter pipe at CB #2 is approximately 1.58 for the 100-year/24-hour storm event undetained developed flow of 6.7 cfs. /S- ►' b/A- #bP9 h = o. ot2 A = /. 27-77q' WP = 3.9i2? r S = (0.G 1) GROUP FOUR,Inc. 16030 Juanita-Woodinville Way NE Bothell, WA 98011 3/ 8/99 GROUP FOUR, Inc . page 1 STAFFORD CREST DIVISION 2 100-YEAR OVERFLOW R/D ANALYSIS --------------------------------------------------------------------- --------------------------------------------------------------------- BASIN SUMMARY BASIN ID: 100D NAME : STAFFORD CREST-2 100-YEAR DEV SCS METHODOLOGY TOTAL AREA. . . . . . . : 9 . 86 Acres BASEFLOWS: 0 . 00 cfs RAINFALL TYPE. . . . : TYPElA PERVIOUS AREA PRECIPITATION. . . . : 3 . 90 inches AREA. . : 4 . 70 Acres TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 86 . 00 TIME OF CONC. . . . . : 27 . 02 min IMPERVIOUS AREA ABSTRACTION COEFF: 0 . 20 AREA. . : 5 . 16 Acres CN. . . . . 98 . 00 PEAK RATE: 6 . 69 cfs VOL: 2 .43 Ac-ft TIME : 510 min Z�EVELoPE 1' FZ6W Culvert Design r 180 I0,000 168 8,000 EXAMPLE ' 6, 156 6,000 De42 Inches (3.5 fall) 6. 5,000 0-120 cfs 5. 144 6. 5. 4,000 � itHw 132 D 3,000 'feet 4_ 5 4, (t) t.s e.e 120 (2) 2.1 7.4 2,000 (3) 2.2 7.7 4• 108 3. ap In lost 3. 96 1,000 3• 800 84 600 500 2. 72 400 ; 300 E�0/ 1.5 1,5 Z N / e N 60 u 200 / / 1.5 Z Z / W 0 54 Q O p W 100 Z j 48 // 80 J / Q u / v 60 w I.0 I.0 42 N 50 0 o HW SCALE NTRANCE 1.0 j 40 D TYPE w 9 1' ►W— 36 30 (1) square*do@ wlth 9 9 W head*all Q 33 20 ( Groove and.ifh W p 30 headwall 2 •8 ,8 a (31 Groove Sad projecting 27 10 T .T 24 6.7 .7 6 To use Scale (2)or(3)Project 21 5 horizontally to Scala(I),then 4 use Straight inclinod line through D and G scale%,of reverse as 6 ,6 3 illustrated, 6 I8 2 15 .5 1.0 12 HEADWATER DEPTH FOR HEADWATER SCALES 2113 CONCRETE PIPE CULVERTS REVISED MAY 1964 WITH INLET CONTROL BUREAU OF PUBLIC ROADS JAN.1963 Figure 3-3.4.2A Concrete Pipe Inlet Control Nomograph Hydraulics Manual Page 3-11 January1997 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL FIGURE 4.4.7j RISER INFLOW CURVES Weir Flow Orifice Flow ------ 100 —- ---- -_ — - i - ^, — - 336 3 �— 30 27 0 24 c N, U 21 c a L 18 � I - E o v 15 - 12 10 — -- --- _ — ly --- i 0.1 .z. •3 .y A 1.0rZ t ti Y s c � 810.0 HEAD IN FEE (measured f Tcrest of riser) 0.160L, SOURCE: USDA-SCS QWIER = 9.739 DH3'2 QORiFICE = 3.782 D 2 H 1 �1�-- Q in cfs, D and H in feet Can 4X4( Sy'-ie L)C:/v 2G 4.4.7-10 1/90 Stafford Crest #97-8008 SECTION V Conveyance System Analysis and Design GROUP FOUR,Inc. 16030 Juanita-Woodinville Way NE Bothell, WA 98011 2/22/99 GROUP FOUR, Inc . page 1 STAFFORD CREST DIVISION 2 REACH SUMMARY Routing based on P3 . 4 family @ 25 yr freq : YrA_1R Hydraulic Gradeline for Reach HGL1 <-FROM-> <--TO--> <FLOW> floss Ent_HGL EntLoss ExtLoss OutLet Inlet AppHead BndHead JunHead HeadWtr -cb/mh- -------- -------- cfs -loss- -Elev-- --loss- --loss- --Elev- --Elev- --loss- --loss- --loss- --Elev- --Rim-- OUTLET 207.00 CB3 OUTLET 10.33 2.68 209.68 0.55 1.10 211.33 213.77 1.00 1.33 0.04 214.14 217.13 CB4 CB3 9.86 0.8S 214.99 0.50 1.00 216.50 216.36 0.52 0.00 0.14 216.12 217.57 CBS CB4 7.12 1.37 217.49 0.26 0.52 218.27 216.62 0.76 0.00 0.17 217.68 219.45 CB6 CBS 5.49 3.52 221.20 0.38 0.76 222.34 230.77 0.33 0.00 0.11 230.55 232.19 CB7 CB6 3.63 0.85 231.39 0.17 0.33 231.89 236.08 0.31 0.00 0.01 235.78 237.59 CBS CB7 3.51 1.32 237.10 0.16 0.31 237.56 242.07 0.14 0.00 0.05 241.97 243.92 039 CBS 2.36 0.34 242.31 0.03 0.14 242.48 243.32 0.04 0.05 0.02 243.35 247.35 CB10 CB9 0.97 0.06 tw & do <dc: Inlet Ctrl Assumed 246.86 0.00 0.00 0.00 246.86 250.70 CB9 244.34 CB9A CB9 1.18 0.04 tw & do <do: Inlet Ctrl Assumed 244.61 0.00 0.00 0.00 244.61 247.41 CB8 241.97 CB8A CB8 1.10 0.02 242.00 0.02 0.03 242.04 241.11 0.00 0.00 0.00 242.04 243.92 CB6 230.57 CB61 CB6 1.87 0.11 tw & do <dc: Inlet Ctrl Assumed 230.83 0.06 0.08 0.01 230.86 233.53 CB61A CB61 1.57 0.08 tw & do <dc: Inlet Ctrl Assumed 231.94 0.00 0.00 0.00 231.94 234.69 CBS 217.68 CB5A CBS 1.63 0.06 217.74 0.03 0.07 217.84 217.03 0.00 0.00 0.00 217.84 219.80 CB4 216.12 CB41 CB4 2.93 0.10 216.22 0.04 0.09 216.35 213.90 0.05 0.00 0.03 216.33 217.13 CB42 CB41 1.38 0.19 216.52 0.02 0.05 216.60 218.64 0.01 0.02 0.01 218.65 221.72 CB42A C1342 0.68 0.01 tw & do <dc: Inlet Ctrl Assumed 218.85 0.00 0.00 0.00 218.85 221.72 CB41 216.33 CB41A CB41 0.87 0.02 216.35 0.01 0.02 216.38 214.29 0.00 0.00 0.00 216.38 217.13 CB3 214.14 CB33 CB3 1.07 0.04 214.19 0.01 0.03 214.23 213.29 0.03 0.03 0.00 214.24 216.S7 CB34 C333 1.02 0.03 214.27 0.01 0.03 214.31 213.68 0.01 0.01 0.00 214.31 216.57 CB35 C334 0.65 0.01 214.30 0.01 0.01 214.32 213.98 0.00 0.00 0.00 214.32 217.80 CB36 CB35 0.38 0.01 tw & do <dc: Inlet Ctrl Assumed 217.46 0.00 0.00 -0.00 217.45 221.37 CB37 CB36 0.40 0.02 tw & do <dc: Inlet Ctrl Assumed 218.28 0.00 0.00 0.00 218.28 221.64 CB38 CB37 0.27 0.00 tw & do <dc: Inlet Ctrl Assumed 218.70 0.00 0.00 0.00 218.70 221.97 CB37 218.31 CB37A CB37 0.15 0.00 tw & do <dc: Inlet Ctrl Assumed 218.37 0.00 0.00 0.00 218.37 221.50 C335 214.32 CB35A CB35 0.32 0.00 214.30 0.00 0.00 214.31 214.1S 0.00 0.00 0.00 214.31 217.S0 2/22/99 GROUP FOUR, Inc . 1 page STAFFORD CREST DIVISION 2 -------------- REACH SUMMARY Routing based on P3 . 4 family @ 100 yr freq Hydraulic Gradeline for Reach HGLI <-FROM-> <--TO--> <FLOW> floss Ent_HGL EntLoss ExtLoss OutLet Inlet AppHead BndHead JunHeaa HeadWtr -cb/mh- -------- -------- cfs -loss- -Elev-- --loss- --loss- --Elev- --Elev- --loss- --loss- --loss- --Elev- --Rim-- OUTLET 207.00 CB3 OUTLET 10.54 2.80 209.80 0.57 1.15 211.52 213.89 1.05 1.40 0.04 214.28 217.13 CB4 C133 10.09 0.89 215.17 0.52 1.05 216.74 216.47 0.55 0.00 0.15 216.34 217.57 C135 CB4 7.29 1.44 217.78 0.27 0.55 218.60 216.69 0.80 0.00 0.17 217.98 219.45 CB6 CBS 5.62 3.69 221.67 0.40 0.80 222.87 230.86 0.35 0.00 0.12 230.63 232.19 CB7 CB6 3.72 0.89 231.52 0.17 0.35 232.04 236.12 0.33 0.00 0.01 235.80 237.59 CB8 CB7 3.60 1.39 237.19 0.16 0.33 237.68 242.11 0.15 0.00 0.05 242.01 243.92 CB9 CB8 2.42 0.36 242.37 0.03 0.15 242.54 243.33 0.04 0.05 0.02 243.36 247.35 CB10 CB9 0.99 0.06 tw & do <dc: Inlet Ctrl Assumed 246.86 0.00 0.00 0.00 246.86 250.70 CB9 0 244.34 CB9A CB9 1.22 0.04 tw & do <dc: Inlet Ctrl Assumed 244.61 0.00 0.00 0.00 244.61 247.41 CB8 242.01 CB8A CB8 1.13 0.03 242.04 0.02 0.03 242.08 241.11 0.00 0.00 0.00 242.08 243.92 CB6 230.63 CB61 CB6 1.92 0.11 tw & do <dc: Inlet Ctrl Assumed 230.84 0.07 0.09 0.01 230.87 233.53 CB61A CB61 1.61 0.08 tw & do <dc: Inlet Ctrl Assumed 231.94 0.00 0.00 0.00 231.94 234.69 CBS 217.98 CB5A CBS 1.67 0.06 218.04 0.04 0.07 218.15 217.04 0.00 0.00 0.00 218.15 219.80 CB4 216.34 CB41 CB4 3.01 0.11 216.45 0.05 0.09 216.59 213.91 0.05 0.00 0.03 216.57 217.13 CB42 CB41 1.42 0.20 216.77 0.03 0.05 216.85 218.64 0.01 0.02 0.01 218.65 221.72 CB42A CB42 0.70 0.01 tw & do <dc: Inlet Ctrl Assumed 218.86 0.00 0.00 0.00 218.86 221.72 CB41 216.57 CB41A CB41 0.90 0.02 216.59 0.01 0.02 216.62 214.29 0.00 0.00 0.00 216.62 217.13 CB3 214.28 CB33 CB3 1.10 0.05 214.33 0.02 0.03 214.37 213.29 0.03 0.04 0.00 214.38 216.57 CB34 CB33 1.04 0.03 214.41 0.01 0.03 214.45 213.68 0.01 0.01 0.00 214.46 216.57 CB35 CB34 0.66 0.01 214.46 0.01 0.01 214.48 213.98 0.00 0.00 0.00 214.48 217.80 CB36 CB35 0.39 0.01 tw & do <dc: Inlet Ctrl Assumed 217.46 0.00 0.00 -0.00 217.45 221.37 CB37 CB36 0.41 0.02 tw & do <dc: Inlet Ctrl Assumed 218.28 0.00 0.00 0.00 218.28 221.64 CB38 CB37 0.28 0.00 tw & do <dc: Inlet Ctrl Assumed 218.70 0.00 0.00 0.00 218.70 221.97 CB37 218.31 CB37A CB37 0.15 0.00 tw & do <dc: Inlet Ctrl Assumed 218.37 0.00 0.00 0.00 218.37 221.50 CB35 214.48 CB35A CB35 0.33 0.00 214.48 0.00 0.00 214.48 214.15 0.00 0.00 0.00 214.48 217.50 3/ 3/99 GROUP FOUR, Inc . page 1 PRIVATE DRAINAGE EASEMENT STAFFORD CREST DIV 2 REACH SUMMARY Routing based on P3 .4 family @ 100 yr freq /UU-J6AR_ Hydraulic Gradeline for Reach HGLI <-FROM-> <--TO--> <FLOW> floss Ent_HGL EntLoss ExtLoss Outlet Inlet AppHead BndHead SunHead HeadWtr -cb/mh- -------- -------- cfs -loss- -Elev-- --loss- --loss- --Elev- --Elev- --loss- --loss- --loss- --Elev- --Rim-- OUTLET 206.50 YD3 OUTLET 2.70 0.34 206.84 0.09 0.18 207.12 204.64 0.16 0.00 0.01 206.96 207.80 YD4 YD3 2.55 0.26 207.22 0.08 0.16 207.47 206.01 0.13 0.00 0.01 207.36 208.60 YD5 YD4 2.25 0.20 207.56 0.06 0.13 207.75 207.36 0.11 0.00 0.01 207.64 210.80 YD6 YD5 2.11 0.19 210.74 0.06 0.11 210.91 210.82 0.10 0.00 0.01 210.82 213.80 YD7 YD6 1.95 0.15 tw & do <dc: Inlet Ctrl Assumed 214.09 0.08 0.00 0.01 214.02 217.80 YD8 YD7 1.78 0.13 tw & do <dc: Inlet Ctrl Assumed 217.07 0.13 0.00 0.01 216.94 222.80 YD9 YD8 1.61 0.25 tw & do <dc: Inlet Ctrl Assumed 224.10 0.11 0.00 0.01 224.00 229.80 YD10 YD9 1.44 0.20 tw & do <dc: Inlet Ctrl Assumed 227.68 0.08 0.00 0.01 227.61 231.10 YD11 YD10 1.27 0.17 tw & do <dc: Inlet Ctrl Assumed 229.06 0.06 0.00 0.01 229.01 232.20 YD12 YD11 1.10 0.13 tw & do <dc: Inlet Ctrl Assumed 229.83 0.11 0.00 0.02 229.74 233.80 YD13 YD12 0.92 0.27 tw & do <dc: Inlet Ctrl Assumed 230.68 0.07 0.00 0.01 230.61 235.40 YD14 YD13 0.76 0.24 tw & do <dc: Inlet Ctrl Assumed 231.33 0.04 0.00 0.01 231.29 234.80 L15 YD14 0.59 0.06 tw & do <dc: Inlet Ctrl Assumed .231.67 0.02 0.00 0.01 231.66 235.80 YD16 L15 0.40 0.05 tw & do <dc: Inlet Ctrl Assumed 232.23 0.01 0.02 0.01 232.24 234.80 YD17 YD16 0.19 0.03 tw & do <dc: Inlet Ctrl Assumed 240.04 O.OQ 0.00 0.00 240.04 243.80 Network LINE1 : Pipe Reach Basin Area --c- --c*A- --Sum- ---Tc- --i-- --QAct Dia -Mann -Slope -QFull Vfull -Vact -Length --tt-- ---------- Id ac --c*A- - min in/hr cfs in --n-- ft/ft cfs fps fps ft min P17 L17 0.11 0.60 0.07 0.07 6.30 2.79 0.19 6 0.012 0.2257 2.90 14.75 8.28 35.00 0.07 P16 L16 0.16 0.49 0.08, 0.15 6.37 2.78 0.40 8 Q.012 0.0103 1.34 3.82 3.35 58.00 0.29 P15 L15 0.13 0.55 0.07 0.22 6.66 2.72 0.59 8 0.012 0.0125 1.47 4.20 3.98 32.00 0.13 P14 L14 0.11 0.60 0.07 0.28 6.79 2.69 0.76 8 0.012 0.0100 1.31 3.76 3.90 70.00 0.30 P13 L13 0.11 0.60 0.07 0.35 7.09 2.64 0.92 8 0.012 0.0145 1.58 4.54 4.71 55.00 0.19 P12 L12 0.13 0.55 0.07 0.42 7.29 2.60 1.10 10 0.012 0.0133 2.75 5.04 4.75 60.00 0.21 P11 L11 0.14 0.53 0.07 0.50 7.50 2.56 1.27 10 0.O1:2 0.0233 3.64 6.67 6.07 60.00 0.16 P10 L10 0.14 0.53 0.07 0.57 7.66 2.52 1.44 10 0.012 0.0655 6.09 11.16 9.13 55.00 0.10 P9 L9 0.13 0.55 0.07 0.64 7.76 2.51 1.61 10 0.012 0.1273 8.49 15.57 11.96 55.00 0.08 PS L8 0.14 0.53 0.07 0.71 7.84 2.49 1.78 12 0.012 0.0500 8.65 11.02 8.67 60.00 0.12 P7 L7 0.14 0.53 0.07 0.79 7.95 2.47 1.95 12 0.012 0.0550 9.08 11.56 9.20 60.00 0.11 P6 L6 0.14 0.53 0.07 0.86 8.06 2.45 2.11 12 0.012 0.0538 8.98 11.43 9.34 65.00 0.12 PS LS 0.11 0.60 0.07 0.93 8.18 2.42 2.25 12 0.012 0.0233 5.91 7.53 =7.02 60.00 0.14 P4 L4 0.15 0.90 0.14 1.06 8.32 2.40 2.55 12 0.012 0.0233 5.91 7.53 7.25 6D.00 0.14 P3 L3 0.15 0.51 0.08 1.14 8.46 2.37 2.70 12 0.012 0.0314 6.86 8.74 8.22 70.00 0.14 IFIR 1 VArTE '7��AIN,A GE C--Y^``{" Al o N 6 vvcs,-r- s/re of G ar S Stafford Crest #97-8008 CONVEYANCE SYSTEM ANALYSIS & DESIGN Private System-YD417 to Vault Catchment Area Summary Table AREA TOTAL IMPERVIOUS PERVIOUS AREA AREA AREA ID (acres) c=0.90 c=0.25 3 0.15 0.06 0.09 4 0.15 0.06 0.09 5 0.11 0.06 0.05 6 0.14 0.06 0.08 7 0.14 0.06 0.08 8 0.14 0.06 0.08 9 0.13 0.06 0.07 10 0.13 0.06 0.07 11 0.15 0.06 0.09 12 0.13 0.06 0.07 13 0.11 0.06 0.05 14 0.11 0.06 0.05 15 0.13 0.06 0.07 16 0.16 0.06 0.10 17 0.11 0.06 0.05 BYPASS 0.0 0.0 TOTAL 1.99 0.90 1.09 GROUP FOUR,Inc. 16030 Juanita-Woodinville Way NE Bothell, WA 98011 2/22/99 GROUP FOUR, Inc . page 2 STAFFORD CREST DIVISION 2 --------------------------------------------------------------------- --------------------------------------------------------------------- REACH SUMMARY Hydraulic Gradeline for Reach Continued <-FROM-> <--TO--> <FLOW> floss Ent HGL EntLoss ExtLoss OutLet Inlet AppHead BndHead JunHead HeadWtr -cb/mh- -------- -------- cfs -loss- -Elev-- --loss- --loss- --Elev- --Elev- --loss- --loss- --loss- --Elev- --Rim-- Network LINE9 : Pipe Reach Basin Area --c- --c*A- --Sum- ---Tc- --i-- --QAct Dia -Mann -Slope -QFull Vfull -Vact -Length --tt-- ---------- Id ac --c*A- - min in/hr cfs in --n-- ft/ft cfs fps fps ft min P9A A9A 0.65 0.67 0.44 0.44 6.30 2.72 1.18 12 0.012 0.0100 3.87 4.93 4.33 45.00 0.17 Network LINE8 : Pipe Reach Basin Area --c- --c*A- --Sum- ---Tc- --i-- --QAct Dia -Mann -Slope -QFull Vfull -Vact -Length --tt-- ---------- Id ac --c*A- - min in/hr cfs in --n-- ft/ft cfs fps fps ft min P8A A8A 0.63 0.64 0.40 0.40 6.30 2.72 1.10 12 0.012 0.0100 3.87 4.93 4.24 30.00 0.12 Network LINE6 : Pipe Reach Basin Area --c- --c*A- --Sum- ---Tc- --i-- --QAct Dia -Mann -Slope -QFull Vfull -Vact -Length --tt-- ---------- Id ac --c*A- - min in/hr cfs in --n-- ft/ft cfs fps fps ft min P61A A61A 0.98 0.59 0.58 0.58 6.30 2.72 1.57 12 0.012 0.0252 6.15 7.82 6.54 46.00 0.12 P61 A61 0.13 0.90 0.12 0.69 6.42 2.70 1.87 12 0.012 0.0100 3.87 4.93 4.89 45.00 0.15 Network LINE5 : Pipe Reach Basin Area --c- --c*A- --Sum- ---Tc- --i-- --QAct Dia -Mann -Slope -QFull Vfull -Vact -Length --tt-- ---------- Id ac --c*A- - min in/hr cfs in --n-- ft/ft cfs fps fps ft min P5A ASA 0.94 0.64 0.60 0.60 6.30 2.72 1.63 12 0.012 0.0100 3.87 4.93 4.72 32.00 0.11 Network LINE41 : Pipe Reach Basin Area --c- --c*A- --Sum- ---Tc- --i-- --QAct Dia -Mann -Slope -QFull Vfull -Vact -Length --tt-- ---------- Id ac --c*A- - min in/hr cfs in --n-- ft/ft cfs fps fps ft min P41A A41A 0.48 0.67 0.32 0.32 6.30 2.72 0.87 12 0.012 0.0100 3.87 4.93 3.98 32.00 0.13 Network LINE4 : Pipe Reach Basin Area --c- --c*A- --Sum- ---Tc- --i-- --QAct Dia -Mann -Slope -QFull Vfull -Vact -Length --tt-- ---------- Id ac --c*A- - min in/hr cfs in --n-- ft/ft cfs fps fps ft min P42A A42A 0.38 0.66 0.25 0.25 6.30 2.72 0.68 12 0.012 0.0100 3.87 4.93 3.71 30.00 0.13 P42 A42 0.42 0.62 0.26 0.51 6.43 2.70 1.38 12 0.012 0.0307 6.78 8.64 6.78 150.00 0.37 P41 A41 0.48 0.59 0.28 1.12 6.80 2.63 2.93 15 0.012 0.0097 6.90 5.62 5.39 59.00 0.18 2/22/99 GROUP FOUR, Inc . page 3 STAFFORD CREST DIVISION 2 REACH SUMMARY Network LINE37 : Pipe Reach Basin Area --c- --c*A- --Sum- ---To- --i-- --QAct Dia -Mann -Slope -QFull Vfull -Vact -Length --tt-- ---------- Id ac --c*A- - min in/hr cfs in --n-- ft/ft cfs fps fps ft min P37A A37A 0.06 0.90 0.05 0.05 6.30 2.72 0.15 12 0.012 0.0100 3.87 4.93 2.36 14,00 0.10 Network LINE35 : Pipe Reach Basin Area --c- --c*A- --Sum- ---To- --i-- --QAct Dia -Mann -Slope -QFull Vfull -Vact -Length --tt-- ---------- Id ac --c*A- - min in/hr cfs in --n-- ft/ft cfs fps fps ft min P35A A35A 0.13 0.90 0.12 0.12 6.30 2.72 0.32 12 0.012 0.0100 3.87 4.93 2.98 22.00 0.12 Network LINES : Pipe Reach Basin Area --c- --c*A- --Sum- ---To- --i-- --QAct Dia -Mann -Slope -QFull Vfull -Vact -Length --tt-- ---------- Id ac --c*A- - min in/hr cfs in --n-- ft/ft cfs fps fps ft min P38 A38 0.11 0.90 0.10 0.10 6.30 2.72 0.27 12 0.012 0.0071 3.26 4.15 2.51 62.00 0.41 P37 A37 0.15 6.71 2.64 0.40 12 0.012 0.0056 2.89 3.68 2.60 145.00 0.93 P36 A36 0.15 7.64 2.47 0.38 12 0.012 0.0184 5.25 6.68 3.88 100.00 0.43 P35 A35 0.27 8.07 2.39 0.65 12 0.012 0.0100 3.87 4.92 3.65 35.06 0.16 P34 A34 0.18 0.90 0.16 0.43 8.23 2.36 1.02 12 0.012 0.0106 3.98 5.06 4.24 36.01 0.14 P33 A33 0.03 0.90 0.03 0.46 8.37 2.34 1.07 12 0.012 0.0477 8.45 10.76 7.38 57.00 0.13 Network LINEl : Pipe Reach Basin Area --c- --c*A- --Sum- ---To- --i-- --QAct Dia -Mann -Slope -QFull Vfull -Vact -Length --tt-- ---------- Id ac --c*A- - min in/hr cfs in --n-- ft/ft cfs fps fps ft min P10 A10 0.67 0.53 0.36 0.36 6.30 2.72 0.97 12 0.012 0.0407 7.80 9.94 6.76 92.00 0.23 P9 A9 0.10 0.90 0.09 0.88 6.53 2.68 2.36 12 0.012 0.0257 6.21 7.90 7.36 91.00 0.21 PS A8 0.05 0.90 0.05 1.33 6.73 2.64 3.51 12 0.012 0.0377 7.51 9.57 9.41 160.00 0.28 P7 A7 0.08 0.90 0.07 1.40 7.02 2.59 3.63 12 0.012 0.0667 9.99 12.72 11.71 96.00 0.14 P6 A6 0.05 0.90 0.05 2.14 7.15 2.56 5.49 12 0.012 0.0771 10.75 13.68 13.75 175.00 0.21 P5 A5 0.09 0.90 0.08 2.82 7.36 2.52 7.12 15 0.012 0.0110 7.36 6.00 6.83 133.00 0.32 P4 A4 0.07 0.90 0.06 4.00 7.69 2.46 9.86 15 0.012 0.0660 18.03 14.69 15.02 43.00 0.05 P3 A3 4.46 8.50 2.32 10.33 15 0.012 0.0496 15.63 12.73 13.61 124.00 0.15 Network LINE37 : Pipe Reach Basin Area --c- --c*A- --Sum- ---Tc- --i-- --QAct Dia -Mann -Slope -QFull Vfull -Vact -Length --tt-- ---------- Id ac --c*A- - min in/hr cfs in --n-- ft/ft cfs fps fps ft min P37A A37A 0.06 0.90 0.05 0.05 6.30 2.72 0.15 12 0.012 0.0100 3.87 4.93 2.36 14.00 0.10 Network LINE35 : Pipe Reach Basin Area --c- --c*A- --Sum- ---To- --i-- --QAct Dia -Mann -Slope -QFull Vfull -Vact -Length --tt-- ---------- Id ac --c*A- - min in/hr cfs in --n-- ft/ft cfs fps fps ft min P35A A35A 0.13 0.90 0.12 0.12 6.30 2.72 0.32 12 0.012 0.0100 3.87 4.93 2.98 22.00 0.12 2/22/99 GROUP FOUR, Inc . page 4 • STAFFORD CREST DIVISION 2 REACH SUMMARY Network LINE3 : Pipe Reach Basin Area --c- --c*A- --Sum- ---Tc- --i-- --QAct Dia -Mann -Slope -QFull Vfull -Vact -Length --tt-- ---------- Id ac --c*A- - min in/hr cfs in --n-- ft/ft cfs fps fps ft min P38 A38 0.11 0.90 0.10 0.10 6.30 2.72 0.27 12 0.012 0.0071 3.26 4.15 2.51 62.00 0.41 P37 A37 0.15 6.71 2.64 0.40 12 0.012 0.0056 2.89 3.68 2.60 145.00 0.93 P36 A36 0.15 7.64 2.47 0.38 12 0.012 0.0184 5.25 6.68 3.88 100.00 0.43 P35 A35 0.27 8.07 2.39 0.65 12 0.012 0.0100 3.87 4.92 3.65 35.06 0.16 P34 A34 0.18 0.90 0.16 0.43 8.23 2.36 1.02 12 0.012 0.0106 3.98 5.06 4.24 36.01 0.14 P33 A33 0.03 0.90 0.03 0.46 8.37 2.34 1.07 12 0.012 0.0477 8.45 10.76 7.38 57.00 0.13 Network LINE35 : Pipe Reach Basin Area --c- --c*A- --Sum- ---Tc- --i-- --QAct Dia -Mann -Slope -QFull Vfull -Vact -Length --tt-- ---------- Id ac --c*A- - min in/hr cfs in --n-- ft/ft cfs fps fps ft min P35A A35A 0.13 0.90 0.12 0.12 6.30 2.72 0.32 12 0.012 0.0100 3.87 4.93 2.98 22.00 0.12 Network LINE37 : Pipe Reach Basin Area --c- --c*A- --Sum- ---Tc- --i-- --QAct Dia -Mann -Slope -QFull Vfull -Vact -Length --tt-- ---------- Id ac --c*A- - min in/hr cfs in --n-- ft/ft cfs fps fps ft min P37A A37A 0.06 0.90 0.05 0.05 6.30 2.72 0.15 12 0.012 0.0100 3.87 4.93 2.36 14.00 0.10 Network LINE41 : Pipe Reach Basin Area --c- --c*A- --Sum- ---Tc- --i-- --QAct Dia. -Mann -Slope -QFull Vfull -Vact -Length --tt-- ---------- Id ac --c*A- - min in/hr cfs in --n-- ft/ft cfs fps fps ft min P41A A41A 0.48 0.67 0.32 0.32 6.30 2.72 0.87 12 0.012 0.0100 3.87 4.93 3.98 32.00 0.13 Network LINE4 : Pipe Reach Basin Area --c- --c*A- --Sum- ---Tc- --i-- --QAct Dia -Mann -Slope -QFull Vfull -Vact -Length --tt-- ---------- Id ac --c*A- - min in/hr cfs in --n-- ft/ft cfs fps fps ft min P42A A42A 0.38 0.66 0.25 0.25 6.30 2.72 0.68 12 0.012 0.0100 3.87 4.93 3.71 30.00 0.13 P42 A42 0.42 0.62 0.26 0.51 6.43 2.70 1.38 12 0.012 0.0307 6.78 8.64 6.78 150.00 0.37 P41 A41 0.48 0.59 0.28 1.12 6.80 2.63 2.93 15 0.012 0.0097 6.90 5.62 5.39 59.00 0.18 Network LINE41 : Pipe Reach Basin Area --c- --c*A- --Sum- ---Tc- --i-- --QAct Dia -Mann -Slope -QFull Vfull -Vact -Length --tt-- ---------- Id ac --c*A- - min in/hr cfs in --n-- ft/ft cfs fps fps ft min P41A A41A 0.48 0.67 0.32 0.32 6.30 2.72 0.87 12 0.012 0.0100 3.87 4.93 3.98 32.00 0.13 Network LINE5 : Pipe Reach Basin Area --c- --c*A- --Sum- ---Tc- --i-- --QAct Dia -Mann -Slope -QFull Vfull -Vact -Length --tt-- ---------- Id ac --c*A- - min in/hr cfs in --n-- ft/ft cfs fps fps ft min PSA A5A 0.94 0.64 0.60 0.60 6.30 2.72 1.63 12 0.012 0.0100 3.87 4.93 4.72 32.00 0.11 2/22/99 GROUP FOUR, Inc . page 5 STAFFORD CREST DIVISION 2 REACH SUMMARY Network LINE6 : Pipe Reach Basin Area --c- --c*A- --Sum- ---Tc- --i-- --QAct Dia -Mann -Slope -QFull Vfull -Vact -Length --tt-- ---------- Id ac --c*A- - min in/hr cfs in --n-- ft/ft cfs fps fps ft min P61A A61A 0.98 0.59 0.58 0.58 6.30 2.72 1.57 12 0.012 0.0252 6.15 7.82 6.54 46.00 0.12 P61 A61 0.13 0.90 0.12 0.69 6.42 2.70 1.87 12 0.012 0.0100 3.87 4.93 4.89 45.00 0.15 Network LINE8 : Pipe Reach Basin Area --c- --c*A- --Sum- ---Tc- --i-- --QAct Dia -Mann -Slope -QFull Vfull -Vact -Length --tt-- ---------- Id ac --c*A- - min in/hr cfs in --n-- ft/ft cfs fps fps ft min P8A A8A 0.63 0.64 0.40 0.40 6.30 2.72 1.10 12 0.012 0.0100 3.87 4.93 4.24 30.00 0.12 Network LINE9 : Pipe Reach Basin Area --c- --c*A- --Sum- ---Tc- --i-- --QAct Dia -Mann -Slope -QFull Vfull -Vact -Length --tt-- ---------- Id ac --c*A- - min in/hr cfs in --n-- ft/ft cfs fps fps ft min P9A A9A 0.65 0.67 0.44 0.44 6.30 2.72 1.18 12 0.012 0.0100 3.87 4.93 4.33 45.00 0.17 PIPE REACH ID No . P10 From: CB10 To : CB9 Pipe Diameter: 1 . 00 ft n: 0 . 0120 Pipe Length 92 . 00 ft s : 0 . 0407 Up invert 246 . 70 ft down invert : 242 . 96 ft Collection Area : 0 . 67 Ac . Design Flow 0 . 97 cfs Dsgn Depth: 0 . 24 ft Pipe Capacity 7 . 80 cfs Design Vel 6 . 76 fps Travel Time : 0 . 23 min Pipe Full Vel 9 . 94 fps PIPE REACH ID No. P3 From: C33 To : OUTLET Pipe Diameter: 1 . 25 ft n: 0 . 0120 Pipe Length 124 . 00 ft s : 0 . 0496 Up invert 210 . 15 ft down invert : 204 . 00 ft Collection Area: 6 . 71 Ac . Design Flow 10 . 33 cfs Dsgn Depth: 0 . 74 ft Pipe Capacity 15 . 63 cfs Design Vel 13 . 61 fps Travel Time : 0 . 15 min Pipe Full Vel 12 . 73 fps 2/22/99 GROUP FOUR, Inc . page 6 STAFFORD CREST DIVISION 2 REACH SUMMARY PIPE REACH ID No. P33 From: CB33 To: CB3 Pipe Diameter: 1 . 00 ft n: 0 . 0120 Pipe Length 57 . 00 ft s : 0 . 0477 Up invert 213 . 12 ft down invert : 210 . 40 ft Collection Area: 0 . 51 Ac . Design Flow 1 . 07 cfs Dsgn Depth: 0 . 24 ft Pipe Capacity 8 .45 cfs Design Vel 7 . 38 fps Travel Time : 0 . 13 min Pipe Full Vel 10 . 76 fps PIPE REACH ID No. P34 From: CB34 To: CB33 Pipe Diameter: 1 . 00 ft n: 0 . 0120 Pipe Length 36 . 01 ft s : 0 . 0106 Up invert 213 . 50 ft down invert : 213 . 12 ft Collection Area: 0 . 48 Ac . Design Flow 1 . 02 cfs Dsgn Depth: 0 . 35 ft Pipe Capacity 3 . 98 cfs Design Vel 4 . 24 fps Travel Time : 0 . 14 min Pipe Full Vel 5 . 06 fps PIPE REACH ID No. P35 From: CB35 To : CB34 Pipe Diameter: 1 . 00 ft n: 0 . 0120 Pipe Length 35 . 06 ft s : 0 . 0100 Up invert 213 . 85 ft down invert : 213 . 50 ft Collection Area: 0 . 30 Ac . Design Flow 0 . 65 cfs Dsgn Depth: 0 . 28 ft Pipe Capacity 3 . 87 cfs Design Vel 3 . 65 fps Travel Time : 0 . 16 min Pipe Full Vel 4 . 92 fps PIPE REACH ID No. P35A From: CB35A To: C235 Pipe Diameter: 1 . 00 ft n: 0 . 0120 Pipe Length 22 . 00 ft s : 0 . 0100 Up invert 214 . 07 ft down invert : 213 . 85 ft Collection Area : 0 . 13 Ac . Design Flow 0 . 32 cfs Dsgn Depth: 0 . 19 ft Pipe Capacity 3 . 87 cfs Design Vel 2 . 98 fps Travel Time : 0 . 12 min Pipe Full Vel 4 . 93 fps 2/22/99 GROUP FOUR, Inc . page 7 STAFFORD CREST DIVISION 2 REACH SUMMARY PIPE REACH ID No. P36 From: CB36 To : CB35 Pipe Diameter: 1 . 00 ft n: 0 . 0120 Pipe Length 100 . 00 ft s : 0 . 0184 Up invert 217 . 37 ft down invert : 215 . 53 ft Collection Area: 0 . 17 Ac. Design Flow 0 . 38 cfs Dsgn Depth: 0 . 18 ft Pipe Capacity 5 . 25 cfs Design Vel 3 . 88 fps Travel Time : 0 . 43 min Pipe Full Vel 6 . 68 fps PIPE REACH ID No. P37 From: CB37 To : CB36 Pipe Diameter: 1 . 00 ft n: 0 . 0120 Pipe Length 145 . 00 ft s : 0 . 0056 Up invert 218 . 18 ft down invert : 217 . 37 ft Collection Area : 0 . 17 Ac . Design Flow 0 .40 cfs Dsgn Depth: 0 . 25 ft Pipe Capacity 2 . 89 cfs Design Vel 2 . 60 fps Travel Time : 0 . 93 min Pipe Full Vel 3 . 68 fps PIPE REACH ID No. P37A From: CB37A To: CB37 Pipe Diameter: 1 . 00 ft n: 0 . 0120 Pipe Length 14 . 00 ft s : 0 . 0100 Up invert 218 . 32 ft down invert : 218 . 18 ft Collection Area: 0 . 06 Ac . Design Flow 0 . 15 cfs Dsgn Depth: 0 . 13 ft Pipe Capacity 3 . 87 cfs Design Vel 2 . 36 fps Travel Time : 0 . 10 min Pipe Full Vel 4 . 93 fps PIPE REACH ID No. P38 From: CB38 To: CB37 Pipe Diameter: 1 . 00 ft n: 0 . 0120 Pipe Length 62 . 00 ft s : 0 . 0071 Up invert 218 . 62 ft down invert : 218 . 18 ft Collection Area: 0 . 11 Ac . Design Flow 0 . 27 cfs Dsgn Depth: 0 . 19 ft Pipe Capacity 3 . 26 cfs Design Vel 2 . 51 fps Travel Time : 0 .41 min Pipe Full Vel 4 . 15 fps 2/22/99 GROUP FOUR, Inc . page 8 STAFFORD CREST DIVISION 2 REACH SUMMARY PIPE REACH ID No. P4 From: CB4 To: CB3 Pipe Diameter: 1 . 25 ft n: 0 . 0120 Pipe Length 43 . 00 ft s : 0 . 0660 Up invert 212 . 99 ft down invert : 210 . 15 ft Collection Area : 6 . 20 Ac . Design Flow 9 . 86 cfs Dsgn Depth: 0 . 66 ft Pipe Capacity 18 . 03 cfs Design Vel 15 . 02 fps Travel Time : 0 . 05 min Pipe Full Vel 14 . 69 fps PIPE REACH ID No. P41 From: CB41 To : CB4 Pipe Diameter: 1 . 25 ft n: 0 . 0120 Pipe Length 59 . 00 ft s : 0 . 0097 Up invert 213 . 56 ft down invert : 212 . 99 ft Collection Area : 1 . 76 Ac. Design Flow 2 . 93 cfs Dsgn Depth: 0 . 57 ft Pipe Capacity 6 . 90 cfs Design Vel 5 . 39 fps Travel Time : 0 . 18 min Pipe Full Vel 5 . 62 fps PIPE REACH ID No. P41A From: C341A To: CB41 Pipe Diameter: 1 . 00 ft n: 0 . 0120 Pipe Length 32 . 00 ft s : 0 . 0100 Up invert 214 . 13 ft down invert : 213 . 81 ft Collection Area : 0 . 48 Ac . Design Flow 0 . 87 cfs Dsgn Depth: 0 . 32 ft Pipe Capacity 3 . 87 cfs Design Vel 3 . 98 fps Travel Time : 0 . 13 min Pipe Full Vel 4 . 93 fps PIPE REACH ID No. P42 From: CB42 To: CB41 Pipe Diameter: 1 . 00 ft n: 0 . 0120 Pipe Length 150 . 00 ft s : 0 . 0307 Up invert 218 .42 ft down invert : 213 . 81 ft Collection Area: 0 . 80 Ac . Design Flow 1 . 38 cfs Dsgn Depth: 0 . 31 ft Pipe Capacity 6 . 78 cfs Design Vel 6 . 78 fps Travel Time : 0 . 37 min Pipe Full Vel 8 . 64 fps 2/22/99 GROUP FOUR, Inc . page 9 STAFFORD CREST DIVISION 2 REACH SUMMARY PIPE REACH ID No. P42A From: CB42A To: CB42 Pipe Diameter: 1 . 00 ft n: 0 . 0120 Pipe Length 30 . 00 ft s : 0 . 0100 Up invert 218 . 72 ft down invert : 218 . 42 ft Collection Area: 0 . 38 Ac . Design Flow 0 . 68 cfs Dsgn Depth: 0 . 28 ft Pipe Capacity 3 . 87 cfs Design Vel 3 . 71 fps Travel Time : 0 . 13 min Pipe Full Vel 4 . 93 fps PIPE REACH ID No. P5 From: CBS To : CB4 Pipe Diameter: 1 . 25 ft n: 0 . 0120 Pipe Length 133 . 00 ft s : 0 . 0110 Up invert 214 .45 ft down invert : 212 . 99 ft Collection Area : 4 . 37 Ac . Design Flow 7 . 12 cfs Dsgn Depth: 0 . 99 ft Pipe Capacity 7 . 36 cfs Design Vel 6 . 83 fps Travel Time : 0 . 32 min Pipe Full Vel 6 . 00 fps PIPE REACH ID No. P5A From: CB5A To: CBS Pipe Diameter: 1 . 00 ft n: 0 . 0120 Pipe Length 32 . 00 ft s : 0 . 0100 Up invert 216 . 77 ft down invert : 216 . 45 ft Collection Area: 0 . 94 Ac . Design Flow 1 . 63 cfs Dsgn Depth: 0 . 45 ft Pipe Capacity 3 . 87 cfs Design Vel 4 . 72 fps Travel Time : 0 . 11 min Pipe Full Vel 4 . 93 fps PIPE REACH ID No. P6 From: C36 To : CBS Pipe Diameter: 1 . 00 ft n: 0 . 0120 Pipe Length 175 . 00 ft s : 0 . 0771 Up invert 228 . 19 ft down invert : 214 . 70 ft Collection Area: 3 . 34 Ac . Design Flow 5 .49 cfs Dsgn Depth: 0 . 51 ft Pipe Capacity 10 . 75 cfs Design Vel 13 . 75 fps Travel Time : 0 . 21 min Pipe Full Vel 13 . 68 fps 2/22/99 GROUP FOUR, Inc . page 10 STAFFORD CREST DIVISION 2 REACH SUMMARY PIPE REACH ID No. P61 From: CB61 To : CB6 Pipe Diameter: 1 . 00 ft n: 0 . 0120 Pipe Length 45 . 00 ft s : 0 . 0100 Up invert 230 . 53 ft down invert : 230 . 08 ft Collection Area: 1 . 11 Ac . Design Flow 1 . 87 cfs Dsgn Depth: 0 . 49 ft Pipe Capacity 3 . 87 cfs Design Vel 4 . 89 fps Travel Time : 0 . 15 min Pipe Full Vel 4 . 93 fps PIPE REACH ID No. P61A From: CB61A To: CB61 Pipe Diameter: 1 . 00 ft n: 0 . 0120 Pipe Length 46 . 00 ft s : 0 . 0252 Up invert 231 . 69 ft down invert : 230 . 53 ft Collection Area: 0 . 98 Ac . Design Flow 1 . 57 cfs Dsgn Depth: 0 . 34 ft Pipe Capacity 6 . 15 cfs Design Vel 6 . 54 fps Travel Time : 0 . 12 min Pipe Full Vel 7 . 82 fps PIPE REACH ID No . P7 From: CB7 To : CB6 Pipe Diameter: 1 . 00 ft n: 0 . 0120 Pipe Length 96 . 00 ft s : 0 . 0667 Up invert 234 . 59 ft down invert : 228 . 19 ft Collection Area : 2 . 18 Ac . Design Flow 3 . 63 cfs Dsgn Depth: 0 . 42 ft Pipe Capacity 9 . 99 cfs Design Vel 11 . 71 fps Travel Time : 0 . 14 min Pipe Full Vel 12 . 72 fps PIPE REACH ID No. P8 From: CB8 To : CB7 Pipe Diameter: 1 . 00 ft n: 0 . 0120 Pipe Length 160 . 00 ft s : 0 . 0377 Up invert 240 . 62 ft down invert : 234 . 59 ft Collection Area : 2 . 10 Ac. Design Flow 3 . 51 cfs Dsgn Depth: 0 . 48 ft Pipe Capacity 7 . 51 cfs Design Vel 9 .41 fps Travel Time : 0 . 28 min Pipe Full Vel 9 . 57 fps 2/22/99 GROUP FOUR, Inc . page 11 STAFFORD CREST DIVISION 2 REACH SUMMARY PIPE REACH ID No. P8A From: C28A To: CB8 Pipe Diameter: 1 . 00 ft n: 0 . 0120 Pipe Length 30 . 00 ft s : 0 . 0100 Up invert 240 . 92 ft down invert : 240 . 62 ft Collection Area: 0 . 63 Ac . Design Flow 1 . 10 cfs Dsgn Depth: 0 . 36 ft Pipe Capacity 3 . 87 cfs Design Vel 4 . 24 fps Travel Time : 0 . 12 min Pipe Full Vel 4 . 93 fps PIPE REACH ID No. P9 From: CB9 To: CB8 Pipe Diameter: 1 . 00 ft n: 0 . 0120 Pipe Length 91 . 00 ft s : 0 . 0257 Up invert 242 . 96 ft down invert : 240 . 62 ft Collection Area: 1 . 42 Ac . Design Flow 2 . 36 cfs Dsgn Depth: 0 . 43 ft Pipe Capacity 6 . 21 cfs Design Vel 7 . 36 fps Travel Time : 0 . 21 min Pipe Full Vel 7 . 90 fps PIPE REACH ID No. P9A From: CB9A To: CB9 Pipe Diameter: 1 . 00 ft n: 0 . 0120 Pipe Length 45 . 00 ft s : 0 . 0100 Up invert 244 .41 ft down invert : 243 . 96 ft Collection Area: 0 . 65 Ac . Design Flow 1 . 18 cfs Dsgn Depth: 0 . 38 ft Pipe Capacity 3 . 87 cfs Design Vel 4 . 33 fps Travel Time : 0 . 17 min Pipe Full Vel 4 . 93 fps 2/22/99 GROUP FOUR, Inc . page 1 STAFFORD CREST DIVISION 2 -------------- RATIONAL DRAINAGE AREA SUMMARY Drainage Area Id: A10 Description. . . . . : LOTS 18-22 CB 10 <---Description--> SubArea SubC L (ft) Slope -Kr-- (min) PERV 0 . 38 0 . 25 IMPERV 0 . 29 0 . 90 Composite "c" Value . . . . . . . . 0 . 53 Time of Conc (min) . . 6 . 30 Drainage Area Id: A3 Description. . . . . : PAVEMENT AREA <---Description--> SubArea SubC L (ft) Slope -Kr-- (min) PERV 0 . 25 IMPERV 0 . 90 Composite "c" Value . . . . . . . . Time of Conc (min) . . 6 . 30 Drainage Area Id: A33 Description. . . . . : PAVEMENT AREA <---Description--> SubArea SubC L (ft) Slope -Kr-- (min) PERV 0 . 25 IMPERV 0 . 03 0 . 90 Composite "c" Value . . . . . . . . 0 . 90 Time of Conc (min) . . 6 . 30 Drainage Area Id: A34 Description. . . . . : PAVEMENT AREA <---Description--> SubArea SubC L (ft) Slope -Kr-- (min) PERV 0 . 25 IMPERV 0 . 18 0 . 90 Composite "c" Value . . . . . . . . 0 . 90 Time of Conc (min) . . 6 . 30 Drainage Area Id: A35 Description. . . . . : PAVEMENT AREA <---Description--> SubArea SubC L (ft) Slope -Kr-- (min) PERV 0 . 25 IMPERV 0 . 90 Composite "c" Value . . . . . . . . Time of Conc (min) . . 6 . 30 Drainage Area Id: A35A Description. . . . . : PAVEMENT AREA <---Description--> SubArea SubC L (ft) Slope -Kr-- (min) PERV 0 . 25 IMPERV 0 . 13 0 . 90 Composite "c" Value . . . . . . . . 0 . 90 Time of Conc (min) . . 6 . 30 2/22/99 GROUP FOUR, Inc . page 2 STAFFORD CREST DIVISION 2 --------------------------------------------------------------------- --------------------------------------------------------------------- RATIONAL DRAINAGE AREA SUMMARY Drainage Area Id: A36 Description. . . . . : PAVEMENT AREA <---Description--> SubArea SubC L (ft) Slope -Kr- - (min) PERV 0 . 25 IMPERV 0 . 90 Composite "c" Value . . . . . . . . Time of Conc (min) . . 6 . 30 Drainage Area Id: A37 Description. . . . . : PAVEMENT AREA <---Description--> SubArea SubC L (ft) Slope -Kr- - (min) PERV 0 . 25 IMPERV 0 . 90 Composite "c" Value . . . . . . . . Time of Conc (min) . . 6 . 30 Drainage Area Id: A37A Description. . . . . : PAVEMENT AREA <---Description--> SubArea SubC L (ft) Slope -Kr-- (min) PERV 0 . 25 IMPERV 0 . 06 0 . 90 Composite "c" Value. . . . . . . . 0 . 90 Time of Conc (min) . . 6 . 30 Drainage Area Id: A38 Description. . . . . : PAVEMENT AREA <---Description--> SubArea SubC L (ft) Slope -Kr-- (min) PERV 0 . 25 IMPERV 0 . 11 0 . 90 Composite "c" Value . . . . . . . . 0 . 90 Time of Conc (min) . . 6 . 30 Drainage Area Id: A4 Description. . . . . : PAVEMENT AREA <---Description--> SubArea SubC L (ft) Slope -Kr-- (min) PERV 0 . 25 IMPERV 0 . 07 0 . 90 Composite "c" Value . . . . . . . . 0 . 90 Time of Conc (min) . . 6 . 30 Drainage Area Id: A41 Description. . . . . : LOTS 49-51 <---Description--> SubArea SubC L (ft) Slope -Kr- - (min) PERV 0 . 23 0 . 25 IMPERV 0 . 25 0 . 90 Composite "c" Value . . . . . . . . 0 . 59 Time of Conc (min) . . 6 . 30 2/22/99 GROUP FOUR, Inc . page 3 STAFFORD CREST DIVISION 2 RATIONAL DRAINAGE AREA SUMMARY Drainage Area Id: A41A Description. . . . . : LOTS 40-42 <---Description--> SubArea SubC L (ft) Slope -Kr-- (min) PERV 0 . 17 0 . 25 IMPERV 0 . 31 0 . 90 Composite "c" Value . . . . . . . . 0 . 67 Time of Conc (min) . . 6 . 30 Drainage Area Id: A42 Description. . . . . : LOTS 46-48 <---Description--> SubArea SubC L (ft) Slope -Kr-- (min) PERV 0 . 18 0 . 25 IMPERV 0 . 24 0 . 90 Composite "c" Value . . . . . . . . 0 . 62 Time of Conc (min) . . 6 . 30 Drainage Area Id: A42A Description. . . . . : LOTS 43-45 <---Description--> SubArea SubC L (ft) Slope -Kr-- (min) PERV 0 . 14 0 . 25 IMPERV 0 . 24 0 . 90 Composite "c" Value . . . . . . . . 0 . 66 Time of Conc (min) . . 6 . 30 Drainage Area Id: A5 Description. : . . . : PAVEMENT AREA <---Description--> SubArea SubC L (ft) Slope -Kr-- (min) PERV 0 . 25 IMPERV 0 . 09 0 . 90 Composite "c" Value. . . . . . . . 0 . 90 Time of Conc (min) . . 6 . 30 Drainage Area Id: A5A Description. . . . . : LOTS 35-39 <---Description--> SubArea SubC L (ft) Slope -Kr-- (min) PERV 0 . 38 0 . 25 IMPERV 0 . 56 0 . 90 Composite "c" Value . . . . . . . . 0 . 64 Time of Conc (min) . . 6 . 30 Drainage Area Id: A6 Description. . . . . : PAVEMENT AREA <---Description--> SubArea SubC L (ft) Slope -Kr-- (min) PERV 0 . 25 IMPERV 0 . 05 0 . 90 Composite "c" Value . . . . . . . . 0 . 90 Time of Conc (min) . . 6 . 30 2/22/99 GROUP FOUR, Inc . page 4 STAFFORD CREST DIVISION 2 --------------------------------------------------------------------- --------------------------------------------------------------------- RATIONAL DRAINAGE AREA SUMMARY Drainage Area Id: A61 Description. . . . . : PAVEMENT <---Description--> SubArea SubC L (ft) Slope -Kr-- (min) PERV 0 . 25 IMPERV 0 . 13 0 . 90 Composite "c" Value . . . . . . . . 0 . 90 Time of Conc (min) . . 6 . 30 Drainage Area Id: A61A Description. . . . . : LOTS 30-34 <---Description--> SubArea SubC L (ft) Slope -Kr-- (min) PERV 0 .47 0 . 25 IMPERV 0 . 51 0 . 90 Composite "c" Value. . . . . . . . 0 . 59 Time of Conc (min) . . 6 . 30 Drainage Area Id: A7 Description. . . . . : PAVEMENT AREA <---Description--> SubArea SubC L (ft) Slope -Kr-- (min) PERV 0 . 25 IMPERV 0 . 08 0 . 90 Composite "c" Value . . . . . . . . 0 . 90 Time of Conc (min) . . 6 . 30 Drainage Area Id: A8 Description. . . . . : PAVEMENT AREA <---Description--> SubArea SubC L (ft) Slope -Kr-- (min) PERV 0 . 25 IMPERV 0 . 05 0 . 90 Composite "c" Value . . . . . . . . 0 . 90 Time of Conc (min) . . 6 . 30 Drainage Area Id: A8A Description. . . . . : LOTS 26-29 <---Description--> SubArea SubC L (ft) Slope -Kr-- (min) PERV 0 . 25 0 . 25 IMPERV 0 . 38 0 . 90 Composite "c" Value . . . . . . . . 0 . 64 Time of Conc (min) . . 6 . 30 Drainage Area Id: A9 Description. . . . . : PAVEMENT AREA <---Description--> SubArea SubC L (ft) Slope -Kr-- (min) PERV 0 . 25 IMPERV 0 . 10 0 . 90 Composite "c" Value . . . . . . . . 0 . 90 Time of Conc (min) . . 6 . 30 2/22/99 GROUP FOUR, Inc . page 5 STAFFORD CREST DIVISION 2 --------------------------------------------------------------------- RATIONAL DRAINAGE AREA SUMMARY Drainage Area Id: A9A Description. . . . . : LOTS 23-25 <---Description--> SubArea SubC L (ft) Slope -Kr-- (min) PERV 0 . 23 0 . 25 IMPERV 0 . 42 0 . 90 Composite "c" Value . . . . . . . . 0 . 67 Time of Conc (min) . . 6 . 30 2/22/99 GROUP FOUR, Inc . page 1 STAFFORD CREST DIVISION 2 RATIONAL DRAINAGE AREA SUMMARY PROPOSED STRUCTURE REACH ID No. CB10 Location North 1000 . 0000 Str Type East 1000 . 0000 Str Cat Catch Basin Rim Elev 250 . 7000 Area/sump: 0 . 00 sf/1 . 50 ft Bottom El : 245 . 2000 Cont Area: A10 Hgrade El : 246 . 8564 ft Bend. . . . . : No special shape Ent type . : Conc Square edge w/headwall Ent Loss : 0 . 000 Exit : 0 . 000 App Vel : 0 . 000 Junct : 0 . 000 Bend: 0 . 000 Reach <Invert> <Diam> < n > <End> P10 246 . 700 12 . 00 0 . 012 Upper PROPOSED STRUCTURE REACH ID No. CB3 Location North 1790 . 0000 Str Type East 1000 . 0000 Str Cat Catch Basin Rim Elev 217 . 1300 Area/sump : 0 . 00 sf/1 . 50 ft Bottom El : 208 . 6500 Cont Area : A3 Hgrade El : 214 . 1447 ft Bend. . . . . : No special shape Ent type . : Conc Square edge w/headwall Ent Loss : 0 . 550 Exit : 1 . 099 App Vel : 1 . 002 Junct : 0 . 039 Bend: 1 . 334 Reach <Invert> <Diam> < n > <End> P4 210 . 152 15 . 00 0 . 012 Lower P33 210 .400 12 . 00 0 . 012 Lower P3 210 . 150 15 . 00 0 . 012 Upper PROPOSED STRUCTURE REACH ID No. CB33 Location North 1847 . 0000 Str Type East 1000 . 0000 Str Cat Catch Basin Rim Elev 216 . 5700 Area/sump : 0 . 00 sf/1 . 50 ft Bottom El : 211 . 6200 Cont Area : A33 Hgrade El : 214 . 2407 ft Bend. . . . . : No special shape Ent type . : Conc Square edge w/headwall Ent Loss : 0 . 015 Exit : 0 . 029 App Vel : 0 . 026 Junct : 0 . 001 Bend: 0 . 034 Reach <Invert> <Diam> < n > <End> P33 213 . 120 12 . 00 0 . 012 Upper P34 213 . 120 12 . 00 0 . 012 Lower a 2/22/99 GROUP FOUR, Inc . page 2 STAFFORD CREST DIVISION 2 STRUCTURE REPORT PROPOSED STRUCTURE REACH ID No . CB34 Location North 1846 . 0000 Str Type East 1036 . 0000 Str Cat Catch Basin Rim Elev 216 . 5700 Area/sump: 0 . 00 sf/1 . 50 ft Bottom El : 212 . 0000 Cont Area : A34 Hgrade El : 214 . 3127 ft Bend. . . . . : No special shape Ent type . : Conc Square edge w/headwall Ent Loss : 0 . 013 Exit : 0 . 026 App Vel : 0 . 011 Junct : 0 . 004 Bend: 0 . 014 Reach <Invert> <Diam> < n > <End> P34 213 . 500 12 . 00 0 . 012 Upper P35 213 . 500 12 . 00 0 . 012 Lower PROPOSED STRUCTURE REACH ID No. CB35 Location : North 1881 . 0000 Str Type : East 1038 . 0000 Str Cat : Catch Basin Rim Elev 217 . 8000 Area/sump : 0 . 00 sf/1 . 50 ft Bottom El : 212 . 3500 Cont Area : A35 Hgrade El : 214 . 3189 ft Bend. . . . . : No special shape Ent type. : Conc Square edge w/headwall Ent Loss : 0 . 005 Exit : 0 . 011 App Vel : 0 . 000 Junct : 0 . 000 Bend: 0 . 000 Reach <Invert> <Diam> < n > <End> P35 213 . 850 12 . 00 0 . 012 Upper P35A 213 . 850 12 . 00 0 . 012 Lower P36 215 . 530 12 . 00 0 . 012 Lower PROPOSED STRUCTURE REACH ID No. CB35A Location North 1903 . 0000 Str Type East 1038 . 0000 Str Cat Catch Basin Rim Elev 217 . 5000 Area/sump : 0 . 00 sf/1 . 50 ft Bottom El : 212 . 5700 Cont Area: A35A Hgrade El : 214 . 3082 ft Bend. . . . . : No special shape Ent type . : Conc Square edge w/headwall Ent Loss : 0 . 001 Exit : 0 . 003 App Vel : 0 . 000 Junct : 0 . 000 Bend: 0 . 000 Reach <Invert> <Diam> < n > <End> P35A 214 . 070 12 . 00 0 . 012 Upper 2/22/99 GROUP FOUR, Inc . page 3 STAFFORD CREST DIVISION 2 STRUCTURE REPORT EXISTING STRUCTURE REACH ID No. C336 Location North 1881 . 0000 Str Type East 1138 . 0000 Str Cat Catch Basin Rim Elev 221 . 3700 Area/sump : 0 . 00 sf/1 . 50 ft Bottom El : 217 . 3700 Cont Area : A36 Hgrade El : 217 . 4529 ft Bend. . . . . : No special shape Ent type . : Conc Square edge w/headwall Ent Loss : 0 . 002 Exit : 0 . 004 App Vel : 0 . 004 Junct : -0 . 000 Bend: 0 . 000 Reach <Invert> <Diam> < n > <End> P36 217 . 370 12 . 00 0 . 012 Upper P37 217 . 370 12 . 00 0 . 012 Lower EXISTING STRUCTURE REACH ID No . CB37 Location North 1881 . 0000 Str Type East 1283 . 0000 Str Cat Catch Basin Rim Elev 221 . 6400 Area/sump : 0 . 00 sf/1 . 50 ft Bottom El : 216 . 6800 Cont Area : A37 Hgrade El : 218 . 2763 ft Bend. . . . . : No special shape Ent type . : Conc Square edge w/headwall Ent Loss : 0 . 000 Exit : 0 . 000 App Vel : 0 . 002 Junct : 0 . 001 Bend: 0 . 000 Reach <Invert> <Diam> < n > <End> P37 218 . 180 12 . 00 0 . 012 Upper P37A 218 . 180 12 . 00 0 . 012 Lower P38 218 . 180 12 . 00 0 . 012 Lower PROPOSED STRUCTURE REACH ID No. CB37A Location North 1867 . 0000 Str Type East 1283 . 0000 Str Cat Catch Basin Rim Elev 221 . 5000 Area/sump: 0 . 00 sf/1 . 50 ft Bottom E1 : 216 . 8200 Cont Area : A37A Hgrade El : 218 . 3719 ft Bend. . . . . : No special shape Ent type . : Conc Square edge w/headwall Ent Loss : 0 . 000 Exit : 0 . 000 App Vel : 0 . 000 Junct : 0 . 000 Bend: 0 . 000 Reach <Invert> <Diam> < n > <End> P37A 218 . 320 12 . 00 0 . 012 Upper 2/22/99 GROUP FOUR, Inc . page 4 STAFFORD CREST DIVISION 2 -------------------- STRUCTURE REPORT EXISTING STRUCTURE REACH ID No. CB38 Location North 1881 . 0000 Str Type East 1345 . 0000 Str Cat Catch Basin Rim Elev 221 . 9700 Area/sump : 0 . 00 sf/1 . 50 ft Bottom El : 217 . 1200 Cont Area : A38 Hgrade El : 218 . 6958 ft Bend. . . . . : No special shape Ent type . : Conc Square edge w/headwall Ent Loss : 0 . 000 Exit : 0 . 000 App Vel : 0 . 000 Junct : 0 . 000 Bend: 0 . 000 Reach <Invert> <Diam> < n > <End> P38 218 . 620 12 . 00 0 . 012 Upper PROPOSED STRUCTURE REACH ID No. CB4 Location North 1747 . 0000 Str Type East 1000 . 0000 Str Cat Catch Basin Rim Elev 217 . 5700 Area/sump : 0 . 00 sf/1 . 50 ft Bottom El : 211 . 7200 Cont Area : A4 Hgrade El : 216 . 1174 ft Bend. . . . . : No special shape Ent type . : Conc Square edge w/headwall Ent Loss : 0 . 501 Exit : 1 . 002 App Vel : 0 . 523 Junct : 0 . 141 Bend: 0 . 002 Reach <Invert> <Diam> < n > <End> P5 212 . 987 15 . 00 0 . 012 Lower P4 212 . 990 15 . 00 0 . 012 Upper P41 212 . 990 15 . 00 0 . 012 Lower PROPOSED STRUCTURE REACH ID No. CB41 Location North 1747 . 0000 Str Type East 1059 . 0000 Str Cat Catch Basin Rim Elev 217 . 1300 Area/sump: 0 . 00 sf/1 . 50 ft Bottom El : 212 . 3100 Cont Area: A41 Hgrade El : 216 . 3342 ft Bend. . . . . : No special shape Ent type . : Conc Square edge w/headwall Ent Loss : 0 . 044 Exit : 0 . 089 App Vel : 0 . 048 Junct : 0 . 029 Bend: 0 . 000 Reach <Invert> <Diam> < n > <End> P41 213 . 560 15 . 00 0 . 012 Upper P41A 213 . 810 12 . 00 0 . 012 Lower P42 213 . 810 12 . 00 0 . 012 Lower 2/22/99 GROUP FOUR, Inc . page 5 STAFFORD CREST DIVISION 2 STRUCTURE REPORT PROPOSED STRUCTURE REACH ID No . CB41A Location North 1715 . 0000 Str Type East 1059 . 0000 Str Cat Catch Basin Rim Elev 217 . 1300 Area/sump: 0 . 00 sf/1 . 50 ft Bottom El : 212 . 6300 Cont Area: A41A Hgrade El : 216 . 3794 ft Bend. . . . . : No special shape Ent type . : Conc Square edge w/headwall Ent Loss : 0 . 010 Exit : 0 . 019 App Vel : 0 . 000 Junct : 0 . 000 Bend: 0 . 000 Reach <Invert> <Diam> < n > <End> P41A 214 . 130 12 . 00 0 . 012 Upper PROPOSED STRUCTURE REACH ID No. CB42 Location North 1747 . 0000 Str Type East 1209 . 0000 Str Cat Catch Basin Rim Elev 221 . 7200 Area/sump : 0 . 00 sf/1 . 50 ft Bottom El : 216 . 9200 Cont Area : A42 Hgrade El : 218 . 6479 ft Bend. . . . . : No special shape Ent type . : Conc Square edge w/headwall Ent Loss : 0 . 024 Exit : 0 . 048 App Vel : 0 . 012 Junct : 0 . 007 Bend: 0 . 016 Reach <Invert> <Diam> < n > <End> P42 218 .420 12 . 00 0 . 012 Upper P42A 218 . 420 12 . 00 0 . 012 Lower PROPOSED STRUCTURE REACH ID No . C342A Location : North 1717 . 0000 Str Type : East 1209 . 0000 Str Cat : Catch Basin Rim Elev : 221 . 7200 Area/sump: 0 . 00 sf/1 . 50 ft Bottom E1 : 217 . 2200 Cont Area: A42A Hgrade El : 218 . 8538 ft Bend. . . . . : No special shape Ent type . : Conc Square edge w/headwall Ent Loss : 0 . 006 Exit : 0 . 012 App Vel : 0 . 000 Junct : 0 . 000 Bend: 0 . 000 Reach <Invert> <Diam> < n > <End> P42A 218 . 720 12 . 00 0 . 012 Upper • 2/22/99 GROUP FOUR, Inc . page 6 STAFFORD CREST DIVISION 2 STRUCTURE REPORT PROPOSED STRUCTURE REACH ID No . CBS Location North 1614 . 0000 Str Type East 1000 . 0000 Str Cat Catch Basin Rim Elev 219 . 4500 Area/sump: 0 . 00 sf/1 . 50 ft Bottom El : 212 . 9500 Cont Area: A5 Hgrade E1 : 217 . 6812 ft Bend. . . . . : No special shape Ent type . : Conc Square edge w/headwall Ent Loss : 0 . 262 Exit : 0 . 523 App Vel : 0 . 759 Junct : 0 . 165 Bend: 0 . 003 Reach <Invert> <Diam> < n > <End> P6 214 . 700 12 . 00 0 . 012 Lower P5 214 . 450 15 . 00 0 . 012 Upper P5A 216 .450 12 . 00 0 . 012 Lower PROPOSED STRUCTURE REACH ID No . CB5A Location North 1614 . 0000 Str Type East 1032 . 0000 Str Cat Catch Basin Rim Elev 219 . 8000 Area/sump : 0 . 00 sf/1 . 50 ft Bottom El : 215 . 2700 Cont Area : A5A Hgrade El : 217 . 8382 ft Bend. . . . . : No special shape Ent type . : Conc Square edge w/headwall Ent Loss : 0 . 033 Exit : 0 . 067 App Vel : 0 . 000 Junct : 0 . 000 Bend: 0 . 000 Reach <Invert> <Diam> < n > <End> P5A 216 . 770 12 . 00 0 . 012 Upper PROPOSED STRUCTURE REACH ID No. CB6 Location North 1439 . 0000 Str Type East 1000 . 0000 Str Cat Catch Basin Rim Elev 232 . 1900 Area/sump : 0 . 00 sf/1 . 50 ft Bottom El : 226 . 6900 Cont Area: A6 Hgrade El : 230 . 5478 ft Bend. . . . . : No special shape Ent type . : Conc Square edge w/headwall Ent Loss : 0 . 379 Exit : 0 . 759 App Vel : 0 . 332 Junct : 0 . 113 Bend: 0 . 001 Reach <Invert> <Diam> < n > <End> P7 228 . 190 12 . 00 0 . 012 Lower P6 228 . 190 12 . 00 0 . 012 Upper P61 230 . 080 12 . 00 0 . 012 Lower 2/22/99 GROUP FOUR, Inc . page 7 STAFFORD CREST DIVISION 2 --------------------------------------------------------------------- STRUCTURE REPORT PROPOSED STRUCTURE REACH ID No. CB61 Location North 1439 . 0000 Str Type East 1045 . 0000 Str Cat Catch Basin Rim Elev 233 . 5300 Area/sump: 0 . 00 sf/1 . 50 ft Bottom El : 229 . 0300 Cont Area: A61 Hgrade El : 230 . 8603 ft Bend. . . . . : No special shape Ent type . : Conc Square edge w/headwall Ent Loss : 0 . 046 Exit : 0 . 093 App Vel : 0 . 062 Junct : 0 . 009 Bend: 0 . 082 Reach <Invert> <Diam> < n > <End> P61 230 . 530 12 . 00 0 . 012 Upper P61A 230 . 530 12 . 00 0 . 012 Lower PROPOSED STRUCTURE REACH ID No . CB61A Location North 1393 . 0000 Str Type East 1045 . 0000 Str Cat Catch Basin Rim Elev 234 . 6900 Area/sump: 0 . 00 sf/1 . 50 ft Bottom El : 230 . 1900 Cont Area : A61A Hgrade El : 231 . 9371 ft Bend. . . . . : No special shape Ent type . : Conc Square edge w/headwall Ent Loss : 0 . 000 Exit : 0 . 000 App Vel : 0 . 000 Junct : 0 . 000 Bend: 0 . 000 Reach <Invert> <Diam> < n > <End> P61A 231 . 690 12 . 00 0 . 012 Upper PROPOSED STRUCTURE REACH ID No . CB7 Location North 1343 . 0000 Str Type East 1000 . 0000 Str Cat Catch Basin Rim Elev 237 . 5900 Area/sump: 0 . 00 sf/1 . 50 ft Bottom El : 233 . 0900 Cont Area : A7 Hgrade El : 235 . 7763 ft Bend. . . . . : No special shape Ent type . : Conc Square edge w/headwall Ent Loss : 0 . 166 Exit : 0 . 332 App Vel : 0 . 311 Junct : 0 . 009 Bend: 0 . 001 Reach <Invert> <Diam> < n > <End> P8 234 . 590 12 . 00 0 . 012 Lower P7 234 . 590 12 . 00 0 . 012 Upper 2/22/99 GROUP FOUR, Inc . page 8 STAFFORD CREST DIVISION 2 STRUCTURE REPORT PROPOSED STRUCTURE REACH ID No. CB8 Location North 1183 . 0000 Str Type East 1000 . 0000 Str Cat Catch Basin Rim Elev 243 . 9200 Area/sump : 0 . 00 sf/1 . 50 ft Bottom El : 239 . 1200 Cont Area : A8 Hgrade El : 241 . 9743 ft Bend. . . . . : No special shape Ent type . : Conc Square edge w/headwall Ent Loss : 0 . 155 Exit : 0 . 311 App Vel : 0 . 140 Junct : 0 . 046 Bend: 0 . 000 Reach <Invert> <Diam> < n > <End> P9 240 . 620 12 . 00 0 . 012 Lower P8 240 . 620 12 . 00 0 . 012 Upper P8A 240 . 620 12 . 00 0 . 012 Lower PROPOSED STRUCTURE REACH ID No. CB8A Location North 1183 . 0000 Str Type East 1030 . 0000 Str Cat Catch Basin Rim Elev 243 . 9200 Area/sump : 0 . 00 sf/1 . 50 ft Bottom El : 239 .4200 Cont Area : A8A Hgrade El : 242 . 0443 ft Bend. . . . . : No special shape Ent type . : Conc Square edge w/headwall Ent Loss : 0 . 015 Exit : 0 . 030 App Vel : 0 . 000 Junct : 0 . 000 Bend: 0 . 000 Reach <Invert> <Diam> < n > <End> P8A 240 . 920 12 . 00 0 . 012 Upper PROPOSED STRUCTURE REACH ID No . CB9 Location : North 1092 . 0000 Str Type : East 1000 . 0000 Str Cat : Catch Basin Rim Elev 247 . 3500 Area/sump: 0 . 00 sf/1 . 50 ft Bottom El : 241 . 4600 Cont Area: A9 Hgrade El : 243 . 3475 ft Bend. . . . . : No special shape Ent type . : Conc grooved end or CMP w/HW Ent Loss : 0 . 028 Exit : 0 . 140 App Vel : 0 . 035 Junct : 0 . 019 Bend: 0 . 047 Reach <Invert> <Diam> < n > <End> P10 242 . 960 12 . 00 0 . 012 Lower P9 242 . 960 12 . 00 0 . 012 Upper P9A 243 . 960 12 . 00 0 . 012 Lower 2/22/99 GROUP FOUR, Inc . page 9 STAFFORD CREST DIVISION 2 STRUCTURE REPORT PROPOSED STRUCTURE REACH ID No. CB9A Location North 1092 . 0000 Str Type East 1045 . 0000 Str Cat Catch Basin Rim Elev 247 . 4100 Area/sump : 0 . 00 sf/1 . 50 ft Bottom El : 242 . 9100 Cont Area : A9A Hgrade El : 244 . 6108 ft Bend. . . . . : No special shape Ent type. : Conc Square edge w/headwall Ent Loss : 0 . 000 Exit : 0 . 000 App Vel : 0 . 000 Junct : 0 . 000 Bend: 0 . 000 Reach <Invert> <Diam> < n > <End> P9A 244 . 410 12 . 00 0 . 012 Upper PROPOSED STRUCTURE REACH ID No . OUTLET Location : North 1790 . 0000 Str Type : East 876 . 0000 Str Cat : Dummy Structure Rim Elev 210 . 0000 Str Diam : 0 . 00 in Bottom E1 : 0 . 0000 Cont Area: Hgrade El : 207 . 0000 ft Bend. . . . . : No special shape Ent type . : Conc Square edge w/headwall Ent Loss : 0 . 000 Exit : 0 . 000 App Vel : 0 . 000 Junct : 0 . 000 Bend: 0 . 000 Reach <Invert> <Diam> < n > <End> P3 204 . 000 15 . 00 0 . 012 Lower + Stafford Crest #97-8008 SECTION VI Special Reports and Studies GROUP FOUR,Inc. 16030 Juanita-Woodinville Way NE Bothell, WA 98011 Stafford Crest #97-8008 SPECIAL REPORTS & STUDIES "Preliminary Geotech Report" Terra Associates, Inc. Project No. T-3685-3 June 30, 1998 January 8, 1999 Add GROUP FOUR,Inc. 16030 Juanita-Woodinville Way NE Bothell,WA 98011 Stafford Crest 497-8008 SECTION VII Basin and Community Plan Areas GROUP FOUR, Inc. 16030 Juanita-Woodinville Way NE Bothell,WA 98011 Stafford Crest #97-8008 BASIN AND COMMUNITY PLAN AREAS The subject property is located in the May Creek Drainage Sub-Basin of the Cedar River Basin and in the Newcastle Community Planning Area. It does not appear as though the project is subject to any specific development limitations or restrictions associated with these Basin and Community Planning Areas. GROUP FOUR,Inc. 16030 Juanita-Woodinville Way NE Bothell, WA 98011 SITE :�•--- - - t�` -'�._ - -- - ------ --------------- .......... -- - _-- -_--- ---- --------; f _ _ o oAR �J/ _ ✓ REEK Y /^ s. a.= r- � _ ,.y /• ` . 1 — OOUALMIE EAST - ' STL. J = COUNTY A MA Figure 1 ..... '• ° "r— - KING COUNTY COMMUNITY PLANNING AREAS Kin C—Y 79B5 S e— Fi��) O 1 a a • 1 • 7 MIW ' 3,30o,8o0 1/90 SITE --- - - - - -----— --- - _---- — - - _SK ISH ✓SN SOU MIE l RIVERIle PUgET Figure 2 DRAINAGE BASINS / ---.'DRAINAG King County 41* �,— -� �.` , ` - ,; _, Major Basin Boundary �T Sub-Basin Boundary •+�' + k. •> Source: - : King County Se itiv Aree. 1 •! ~ �' ` - ou ✓ f _ Map Folio,Wetlands Supplement '• �- 3 — A .„x.env ..r.,. � l� ..-vt . ,f +`\`` ,' BAsr 4 O 1 2 3 4 6 6 7 !Mlles 1:300,000 1190 Stafford Crest #97-8008 SECTION VIII Other Permits GROUP FOUR,Inc. 16030 Juanita-Woodinville Way NE Bothell, WA 98011 Stafford Crest #97-8008 OTHER PERMITS HPA GROUP FOUR,Inc. 16030 Juanita-Woodinville Way NE Bothell, WA 98011 Stafford Crest #97-8008 SECTION IX Erosion/Sediment Control Design GROUP FOUR,Inc. 16030 Juanita-Woodinville Way NE Bothell,WA 98011 --7 C-P o�7,vj, Z��CP7-4 —�Ram Wrr)4 P-6Nb 13677*OA MIMIJEW-116)J�: SG ,57YS"--7 CO) #WL- 5 G -5-y 6 7 G:) 1-f-t-o (-, '7 X :3 ? :=> -7-eI6 0 Coi ty w 4- Stafford Crest #97-8008 SECTION X Bond Quantities Worksheet R/D Facility Summary Sheet and Sketch Declaration of Covenant GROUP FOUR,Inc. 16030 Juanita-Woodinville Way NE Bothell, WA 98011 R KING COUNTY, WASHINGTON, SURFACE WATER DESIGN RETENTION/DETENTION SUMMARY SHEET MANUAL ; Development STA gyp' C R-657'Z y V Z Date Location ENGINEER 11 DEVELOPER Name Iso� Name Firm v N Firm CONTA C: Address o (A) '�!Z (. Address A: ' � Goa 5%80/� C w Phone yZ y— Phone yz < Z } • Developed Site/O. 3 acres Number of Lots • Number of Detention Facilities On Site • Detention provided in regional facility [� Regional Facility location • No detention required Acceptable receiving waters • Downstream Drainage Basins Basin A Immediate Major Basin fit��C'R Basin B Basin C Basin D TOTAL INDIVIDUAL BASIN Drainage Basin(s) A B C p Onsite Area o Offsile Area 6 Type of Storage Facility---� U Live Storage Volume Predeveloped Runoff Rate 2 year 8 10 year 2 • Q ,a Postdeveloped Runoff Rate 100 year 6 3 t . 2 year G Z 10 year Developed Q ' 100 year C• Type of Restriction Size of Orifice/Restriction NoTC Orifice/Re �I siriction No.1 2•S CE No.2 No.3 No.4 No.5 LIVE STORAGE VOLUME REO'D- 34,598 C.F. LIVE STORAGE VOLUME PROV'D: 34,687 C.F. WATER QUALITY VOLUME REQ'D- 9,716 C.F. 15" OUT WATER QUALITY VOLUME PROV'D- 9,728 C.F. TO CB 2 FLOW RESTRICTOR 5 SEE PLAN DETAIL - (ABOVE RIGHT) r- ----- -- --� TYPE 2-54" _1 MH BASE / i J 4'f 7 a -- -- ---'INSIDE DIMENSION N 36" ACCESS RISER NOT INCLUDINGIINTERIOR WALLS) W/STD. GALV. STEPS I I 36"x36"NOTCH w OR LADDER (TYP.) INV. 200.75 F f- 5' II� w Z 2 J // r- o 0 INSPECTION PORT -i I I w A o 6" PVC 0 Z 37' INV. 206.00 0 a I ILA INV. 202.00 NSFROM CB O w 9 '00 68'27'15"\ 4'f -o L , C� IN FROM INLET 3 NOTES: 19, 1. THIS IS NOT A STRUCTURAL PLAN. IT IS INTENDED FOR DIMENSIONS AND ELEVATIONS PURPOSES ONLY. INSIDE DIMENSION TO BE INCREASED TO ACCOUNT FOR INTERIOR WALLS. SEE STRUCTURAL PLANS FOR VAULT DESIGN. STRUCTURAL PLANS MUST BE DESIGNED & STAMPED BY A REGISTERED PROFESSIONAL STRUCTURAL ENGINEER. 2. ALL METAL PARTS: CORROSION RESISTANT. STEEL PARTS GALVANIZED & ASPHALT COATED (TREATMENT 1 OR BETTER). 3. PROVIDE WATER STOP AT ALL CAST IN PLACE CONSTRUCTION JOINTS. PRECAST VAULTS SHALL HAVE APPROVED RUBBER GASKET SYSTEM. DETENTION VAULT PLAN VIEW SCALE: 1" = 20' PROPOSED __ ' GRADE � � ....... ._ 214 EXISTING - GRADE 212R - - - - - - - - - - - - - - - - - -- - - - ---- - --- --- --- ---- 212 -VARIES k i 24"0 INSPECTION PORT 210 -- 210 N / / 208 - - - -- - -- ---- ---/ INSIDE TOP OF VAULT= 208.00 208 / _... v _H.W.L. 207.0 206 _TOP BAFFLE WALL= 206.00 � � --- - -- ----------- 206 204 202 - 36"x36" -- - - NOTCH--- - - ------ -- 202 INV. 200.75 200 - - ----------�-- - - - --------- -- 200 INSIDE BOTTOM OF VAULT= 196.50 198 - ---------- 198 DETENTION VAULT SECTION SCALE: I " = 20'(H) 1 2'(V) FRAMES, GRATES & ROUND SOLID, LOCKING COVERS 10 MATCH FINAL GRADE MARKED "DRAIN" (CIRCUMFERENTIAL STD. GALV. L=0.90' H=1.30' STL. STEPS & LADDER LIFT GATE ROD O.F. 207.00 18" RISER NOTCH WEIR DETAIL Q NOTCH WEIR (SEE DETAIL) NO SCALE ,' O ELEV. 205.70 e• � V) PIPE SUPPORT(S) 3"x0.90 GA. BOLT OR -� IMBED 2" IN WALL AT to MAX. 3' SPACING, MIN. ONE SUPPORT 15" INV. 200.75 WATERTIGHT SHEAR z_ GATE ASSY. PER :2 1.75' WATER WSDOT/APWA STD. N QUALITY PLAN B-3. °' 18" RISER PIPE ELEV= 199.00 RESTRICTOR PLATE ELEV= 198.50 W/ ORIFICE=2-1/2"0 O.C. (SHARP EDGE, `y 6". SEDIMENT SHOP DRILLED) 4 STORAGE STANDARD 54"0 TYPE 2 BASE SECTION 5 FLOW RESTRICTOR DETAIL N.T.S. r, Stafford Crest #97-8008 DECLARATION OF COVENANT The Declaration of Covenant is required for privately maintained commercial retention/detention facilities only. As the proposed R/D facility will be maintained by the City of Renton, a Declaration of Covenant is not required for this project. GROUP FOUR,Inc. 16030 Juanita-Woodinville Way NE Bothell, WA 98011 Stafford Crest 497-8008 a f SECTION XI Maintenance and Operations Manual GROUP FOUR,Inc. 16030 Juanita-Woodinville Way NE Bothell, WA 98011