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Home My WebLink About03019 - Technical Information Report � \ � m Technical Information Report for the Plat of Maureen Highlands Prepared for: Wilshire Investments LLC 1285 140`h Place NE Bellevue, WA 98007 Prepared by: Hugh G. Goldsmith & Associates, Inc. ' March 2002 , Revised June 2002 ' 3 0 /9 I �- � ,-+--' i `. i .+ ` - Technical Information CIT�r OF RENTO�'v RECEIVED Report �uh � � �uuz BUILDING DIVISION for the I Plat of Maureen Highlands Prepared for: Wilshire Investments LLC 1285 140`h Place NE Bellevue, WA 98007 Prepared by: Hugh G. Goldsmith & Associates, Inc. ��; � ��, � � i' �f µ�.� 1y ,�7 � '�C�G� W E''S1Y �'C� � � �" � Y � a ♦ � `�� a .� �'� �; �% �� b ` ` f '�� h� Z' 1 w � j � /� x`II� ■ � V� / C ■ %'1 l � �J�pC` �, �j,1�tlr � � 2a59'] � ..� 36'J'JO / 'c' AF Q��i �`'�� `4� '�F3 ¢4�9 ��rj�� p� G'S'i'E� `V � .�`i'E S �G� �S� E^�'� ��L E� March 2002 �AL Ex - E� 2,2�vs Revised June 2002 E,�P=�ES 8, =2,�,� d Hugl� G. Go1ds�11ith � & .-�s�ci�tes. Inc, Tab/e of Contents 1. Project Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1 2. Conditions and Requirements Summary . . . . . . . . . . . . . . . . . . . 2-1 3. Offsite Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1 Task 1.Study Area Definition and Maps . . . . . . . . . . . . . . . . . . . . 3-1 Task 2.Resource Review . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3 Task 3.Field Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5 Task 4.Drainage System Description and Problem Description . . . . 3-6 Task 5.Mitigation of Existing or Potential Problems . . . . . . . . . . . . 3-18 4. Flow Control and Water Quality Facility Analysis and Design . . . . . 4-1 5. Conveyance System Analysis and Design . . . . . . . . . . . . . . . . . . . 5-1 6. Special Reports and Studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1 7. Other Permits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-1 8. ECS Analysis and Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-1 9. Bond Quantities, Facility Summaries, and Declaration of Covenant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-1 10. Operations and Maintenance Manual . . . . . . . . . . . . . . . . . . . . . 10-1 Figures 1 Site Plan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i 2 Vicinity Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2 3 Developed Conditions Basin Plan . . . . . . . . . . . . . . . . . . . . . . . . 1-3 4 SCS - Soils Survey Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4 5 White Fence Ranch Storm Drain System . . . . . . . . . . . . . . . . . . . 3-12 6 Cedar River Detention Facility . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-8 I� 7 Cedar River Detention Facility - Control Structure . . . . . . . . . . . . . 4-9 I 8 Cedar River Basin Flow Duration Curve . . . . . . . . . . . . . . . . . . . 4-14 9 May Creek Detention Facility . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-17 10 May Creek Detention Facility - Control Structure . . . . . . . . . . . . . 4-18 11 May Creek Detention Flow Duration Curve . . . . . . . . . . . . . . . . . 4-23 12 Hydraulic Gradeline Calculation Summary . . . . . . . . . . . . . . . . . . 5-2 Appendices A King County Sensitive Area Folio B Proposed May Creek Basin Action Plan Basin Maps Exhibits Full size in Back Pocket City of Renton Development Services Division TECHNICAL INFORMATION REPORT (TIR) WORKSHEET Part 1 PROJECT OWNER AND Part 2 PROJECT LOCATION AND PROJECT ENGINEER DESCRIPTION Project Owner Project Name Wilshire Investments LLC Maureen Highlands Address Location 1285 140th Place NE Township 23 N Phone Bellevue.WA. 98007 Range 5E Project Engineer Keith Goldsmith Section 11 Company Hugh G. Goldsmith&Associates, Inc. Address/Phone PO Box 3565,Bellevue,WA 980091425.462.1080 Part 3 TYPE OF PERMIT APPLICATION Part 4 OTHER REVIEWS AND PERMITS � Subdivisi�n ❑ DFW HPA ❑ Shoreline Management ❑ Short Subdivision ❑ COE 404 ❑ Rockery � Grading ❑ DOE Dam Safety ❑ Structural Vaults ❑ Commercial ❑ FEMA Floodplain ❑ Other ❑ Other ❑ COE Wetlands Part 5 SITE COMMUNITY AND DRAINAGE BASIN Community Drainage Basin May Creek/Cedar River Part 6 SITE CHARACTERISTICS 0 River ❑ Floodplain � Wetlands ❑ Stream ❑ Seeps/Springs ❑ Critical Stream Reach ❑ High Groundwater Table ❑ Depressions/Swales � Groundwater Recharge ❑ Lake � Other ❑ Steep Slopes Part 7 SOILS Soil Type Slopes Erosion Potential Erosive Velocities Aqc 0-5% Low Low Bh 0-5% Low Low ❑ Additional Sheets Attached Part 8 DEVELOPMENT LIMITATIONS REFERENCE LIMITATION/SITE CONSTRAINT ❑ Ch. 4-Downstream Analysis O O ❑ ❑ ❑ ❑ ❑ Additional Sheets Attached Part 9 ESC REQUIREMENTS MINIMUM ESC REQUIREMENTS MINIMUM ESC REQUIREMENTS DURING CONSTRUCTION FOLLOWING CONSTRUCTION � Sedimentation Facilities � Stabilize Exposed Surface � Stabilized Construction Entrance � Remove and Restore 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 SAO and open space � Construction Sequence preservation areas ❑ Other ❑ Other Part 10 SURFACE WATER SYSTEM ❑ Grass Lined Channel ❑ Tank � Infiltration Method of Analysis � Pipe System ❑ Vault � Depression ❑ Open Channel ❑ Energy Dissipator ❑ Flow Dispersal Compensation/Mitigation ❑ Dry Pond � Wetland ❑ Waiver of Eliminated Site Storage � Wet Pond � Stream � Regional Detention Brief Description of System Operation Facility Related Site Limitations Reference Faciliry Limitation Part 11 STRUCTURAL ANALYSIS Part 12 EASEMENTS/TRACTS ❑ Cast in Place Vault � Drainage Easement � Retaining Wall � Access Easement ❑ Rockery> 4'High ❑ Native Growth Protection Easement ❑ Structural on Steep Slope ❑ Tract ❑ Other ❑ Other Part 13 SIGNATURE OF PROFESSIONAL ENGINEER ' I or a civil engineer under my supervision have visited the site. Actual site conditions as observed were incorporated into this worksheet and the attachments. To the best of my knowledge the information provided here is accurate. `. � _�� -o � � Signed/Date 1. Project Overview A preliminary site plan for the proposed development is shown in Figure 1. The Maureen Highlands Preliminary Plat proposes 124 single family units on a currently undeveloped parcel. The plat and adjacent Morrison ownership area is 38.52 acres of which 1.67 acres is in the project's BLA area. A vicinity map showing the location of the project site is shown on Figure 2. In general the project is located on the East Renton Plateau between the existing plats of Windwood and White Fence Ranch. The project site is located entirely within the City of Renton. The eastern plat boundary is the boundary between the City of Renton and King County. Access to the site is directly from N.E. 4th Street. N.E. 4`" Street is referred to as S.E. 128"' Street within King County to the east of the site. Portions of the project are in two drainage basins, the May Creek and Cedar River basin. A combination detention/wetpond facility is proposed to be constructed in either basin. The Cedar River facility will discharge to the Plat of Windwood conveyance system. The May Creek facility will discharge to the SE 124�' Street storm drain system ultimately draining toward May Creek. Details of the stormwater control plan for the Plat of Maureen Highlands and the downstream drainage system are given herein. 1-1 R99095-1340 Goldsmith& Associates Ted:nrc�!Ir�fannation Report fnr the Plat qjMa«ree�� Higklurids ^_l .(RNl6 COVN711 N i � I WINDWOOD I ) �� pTY OF pENTON � � ��TM n. � cKme courtrl i I i : I � 0 o ' 5 I � r � n A P � , y�; i � � I i = I= g� WHI E F NC = (_ = ANC _ � �i I I � �I�I n I (CITY OF RENTON7 i � �'. 1 I � _ � I � II11r�� _ � � ��iH�i, iaTr or rtcHroNl — _ 3 - sE as7h ai.�Kw6 cow�rr 0 ^ PLOTiED:99095�02.drg MBARBE OI/31/02 R:S JOB NO: �H/��ugh G. Goldsmith & Associates, IIIC. SCALE: I"-300' VIEW: FiGURE � � 1rU�WI� BII��DCCIS • Surveyors ' P�CIS DATE: Jan31.200i xREF: SITE PLAN � ORAWN: MBARBER LSF: ,. 1215 114th dvenne S6 � � ��. .s �� oES��NEo: F�o BK: MAUREEN HIGHLANOS � P.O. Box 9585 'fEL• (425)482-1080 � Bellevae, �A 98009 PAY: (425) 462-7719 APPROVED: PG/: � ACAD OWG.: 99095E02. ��ssF: KIN6 COUNTY WASHINGTON Y N �� o . ent $ �\ � � . . Uah R� .` e Z � ° $ . � � � � a R NT � _ � m � W Q N n st � � E12 i SL I 3 0 (� .�� g � 1 � � � ; y � �� '"' �a �e`�. � � � e Ra �-.� �'�� a Q � , :� �of�� o s � d SF �= . ' �, � �� .� m �: t�� ` :� o\ :� �' � �--`' •.•� � .._ � � �-..- � : . : : F � ��. �.. 0 1O PLOTTED:99095v02.dvg NBARBE OV31/02 10:1 JOB NO: 0 � Hugh G. WI�I.LL � �HOCiH1�G$� li1C. SCALE: P-4000' VIEW: FIGURE : Consultin� �ineers - Surveyors • Planners DATE: Yay II.2001 XREF: � 1z15 �,+�n e.�� A„N: „AB �SF: VICINITY MAP < a�u��,ie�eoo4 oES��N�: F�o BK: M A U R E E N H I C�H L A N D S 2 � P.O. Bo: 3565 T�: (425) 462-1080 : Bellerae, �A �800� i1%: (425�462-7719 APPROVED: PG�: � AGAD DrG.: 99095r02. �¢SSF: CITY OF RENTON WASHIN�TON �ii�nnut m�.'�,P�.cU��,PLOTS` \39035EOB.Erq +a�1� 33095COB Evq HwEu�i tl6/i9/O2 Ii�.aO'�or srxi o,N[rt Sr�ct� Sis�. �oe�+0�. e�,� . ��_-��o.� � CITY OF � o� -� RENTON WILSHIRE INVESTMENTS L.L.C. � F=� "° '�' MAUREEN HIGHLANDS �� Planning/Building/Public Works Dept. N0. 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AE'�Ra�✓�rsKai•, � ii � r � � Q � � 93 �-i•e% '� t ti --- ��--- - • '�--�-�-- `-�`� ' ------ --- -t` -- � -�''- - -- r - �'---+-------- 3 I '� • O. � �� . `��,, -+�,iT� % � 'jA � AgBi \ � F UR 9 ,)• . �' �„ r�� r' 4 I g � No i o r (La�,eaS. ' C USD1�^kCS-'� LS M , !NG C I �W T. _ ' .. E nga �'Foc, — -�- ,. i, . � �' , ^ ' .� :;i••• •.� ° ` .. :�. • . . . . v E.-'� . � . .i;• `;'�;Ag� •,,1 /��/`�. l..! „ \•� . � �'' •�„-�°�. 2. Conditions and Requirements Summary The City Council should approve the Preliminary Plat subject to the following conditions: 1. Compliance with ERC Mitigation Measures: The applicant is required to comply with the Mitigation Measures,which were required by the Environmental Review Committee Threshold Determination. Response is provided by the designs to be reviewed and approved by the applicable city department. 2. A "will serve" letter must be obtained from Water District 90 prior to obtaining building permits. The will serve letter must be provided to the Development Services Division prior to recording the plat. A Letter of Water Availability has been provided to the Development Services Division. 3. The applicant shall either draft and record a Homeowner's Association or a maintenance agreement for the maintenance of all common improvements, including private stormwater facilities, utility and other easements, and other common areas, including all tracts. A draft of the document shall be submitted to the City of Renton Development Services Division for review and approval by the City Attorney prior to the recording of the final plat. This document will be drafted and provided to the Development Services Division for approval. 4. Payment of impact fees to the Issaquah School District for school use. This payment will be provided as required. 5. The applicant shall provide a public street link to NE 4th Street in the vicinity of , Proposed Lots 5,6 or 7. The location can be determined by Development Services to provide the best separation between existing roads and/or driveways east and west of the subject site was well as appropriate alignment with any road or driveway coming , from the south side of NE 4th Street. I The public street link has been incorporated as required. 6. The plat shall be reduced by one or two lots if required to provide for the roadway to NE 4th Street. No reduction in lots were required. 7. The applicant shall provide certification of minimum water pressure within 30 days of this decision. A letter certifying minimum pressure has been provided to the Development � Services Division. 8. The tract proposed along the eastern boundary of the subject site where title is not clear should be provided to the homeowner's association and landscape easements should be conveyed to the properties abutting that tract so that homeowners may , maintain respective portions if they so chose. This will be responded to and submitted to the Development Services Division ', for approval. 2-� R99095-1.340 Goldsmith& Associates Technica(/nformation ReportJor the Plat oJMuureen Highlands I 3. Offsite Analysis Task 1. Study Area Definition and Maps Existinq Site Conditions and Drainaqe Patterns The project site is located in the upper reaches of two major drainage basins, the Cedar River and the May Creek Basins. The majority of the site and frontage improvement area is in the May Creek Basin (34.23 acres) with the remaining 4.86 acres in the Cedar River Basin. For a regional basin plan refer to the enclosed Exhibit 1. For a more detailed existing conditions drainage plan refer to the enclosed Exhibit 2. The project site is located approximately 1.5 miles up stream of May Creek and 1.7 miles upstream of the Cedar River. Towards the southwest property corner there is a low ridge bisecting the site. This ridge runs from the northwest to the southeast. This ridge is the major basin boundary between the Cedar and May Creek Basins. To the southwest of this ridge drainage is directed towards the Cedar River at a uniform slope of about 2.5%. To the northeast of the ridge drainage is directed towards May Creek through White Fence Ranch and Streams 0291 D and 0291A at a uniform slope of about 2.0%. There is a second ridge located at the north end of the project site within the May Creek Basin. There are drainage ditches along the north, south and eastern property boundaries. A description of the areas that drain to these ditches is given below. The majority of the site in the May Creek Basin drains by either sheet flows or by the vee drains described below above towards a ditch along the eastern property boundary. This ditch conveys drainage towards the Plat of White Fence Ranch through a ditch located in the S.E. 124�' Street right-of-way. At the intersection of S.E. 124"' Street and 155"' Avenue S.E. drainage enters a closed storm drain system. This system ultimately discharges to streams 0291 D and 0291 A before entering May Creek approximately 1.5 miles downstream of the site. Please refer to Exhibit 1 and 2 for basin plans showing the existing conditions drainage pattern. A detailed description and analysis of this downstream drainage systems is given in Task 4. As described above there is a small ridge located along the north end of the site. Drainage on the north side of this ridge does not drain to the eastern ditch but drains directly across lots 28-32 or to the ditch running along the north property boundary before entering the Plat of White Fence Ranch drainage system. Drainage from the eastern ditch and the area north of the northern ridge converge at the 24" concrete culvert located in S.E. 156`h Avenue. Currently, there is one existing residence located at the south end of the property. Nearly the entire remaining project site area is grass covered. The site was originally forested prior to being cleared in 1989. Since the site was cleared it has been used for farming activities. Subsequent to the clearing activity several feeder drains have been excavated to facilitate drainage of the site towards the eastern site boundary. These drains are vee shaped ditches approximately 1 foot deep and 2 feet wide at the top. Also on site four wetlands have been identified. For a detailed assessment of these on-site wetlands please refer to the report titled Maureen Highlands- Renton, Washington Sensitive Areas and Mitigation Report, Talasaea, May 2001. Wetland D is identified on Exhibit 2. This wetland is also referred to as Wetland 22b by the King County Wetland SAO map. Observed soil conditions on site are consistent with the Aldennrood soils series description identified by the SCS soils survey map. 3-1 Hu�yr�u;_� :11i Gold�mi[h c� .a;s��citilc• 7c�l� �,��tl l��j ;vrrafrnn R�p�n�t Ior t{rc Pl<N��j,�icauee�i H�>�r,, .. There is very little off-site area that drains across the project site. Approximately 3.3 ac. of the property adjacent to the west of the site sheet flows towards the east before crossing the site as shown on Exhibit 2. A portion of this off-site drainage area drains towards the various wetlands located on the project site before entering the ditch along the eastern property boundary. The portion of the site within the Cedar River Basin sheet flows to the southwest corner of the site where it is enters the ditch running along N.E. 4th Street. Directly downstream of where on- site drainage combines with the ditch drainage runoff enters a 12"diameter pipe that is connected to the Plat of Windwood conveyance system. This drainage system is connected to Windwood detention pond as shown on Exhibit 1. 3-2 R99095-L340 Goldsmith & Associates Technica!Informution Report for the Plat ojMaureen Hiq/du��rLr Task 2. Resource Review The following is a summary of the resources and documents reviewed for this downstream �� analysis. Relevant maps from these references have been included in the attached appendices as referred to below. • Sensitive Area Folios (Appendix A) The Sensitive Area Map Folio for King County, Washington (December 1990) indicates potential sensitive areas within, adjacent, and downstream of the proposed site. Copies of these maps are included in the attached appendix. o Wetlands: The SAO folio maps identify that Wetland 22b is located on the proposed plat site. Wetland 22b is referred to as Wetland D on the enclosed drainage exhibits and in the project wetland report (Talasaea, 2001). Wetlands 20b and 21 b are identified as being downstream of the site in the May Creek Basin. o Streams and 100-year Flood Plains: There are no streams identified on the project site. In the May Creek Basin the SAO maps indicates a stream 0.6 miles downstream of the site to the east. This stream is a tributary of May Creek. This stream is referred to as Stream 0291A in the Proposed May Creek Basin Action Plan. In the Cedar River Basin, a stream is shown approximately 1.0 miles downstream of the site to the south west. This stream is identified as Stream 0307 in the Cedar River Basin Plan. No portion of the site or the downstream drainage system is located in a flood plain as identified by the SAO folio maps. o Erosion Hazard Areas: There are no erosion hazard areas identified near the project study area. o Landslide Hazard Areas: No landslide hazard areas are identified near the project study area. o Seismic Hazard Areas: No seismic hazard areas are located near the project study area. o Coal Mine Hazard Area: No coal mine hazard areas are located near the project study area. • USDA SCS King County Soils Survey - (Figure 4) SCS soils mapping indicates that the proposed project site is underlain by Alderwood soils {gravelly sandy loam) and a small area of Bellingham (silt loam). • Floodplain / Floodway (FEMA) Maps There are no floodplains identified on-site or adjacent to the project site. The nearest I floodplain areas indicated on the FEMA maps are directly adjacent to the Cedar River and ' May Creek, approximately 1.7 miles and 1.5 miles downstream of the site respectively. 3-3 R9909i-1.340 Goldsmith&Associates Techr�ical I�ijornrntian Report for the Plat of Maureen Highlands An area of localized flooding has been identified directly downstream of the site in the Plat of White Fence Ranch. This flooding is discussed in Tasks 4 and 5 sections of this off- site analysis. • Adopted Basin Plans and Finalized Drainage Studies - (Appendix B) The project is located in the May Creek and Cedar River Basin. The Adopted May Creek Basin Action Plan (April 2001)was reviewed for this downstream analysis. Basin maps from this report showing the project site location have been included in Appendix C of this report. Other drainage studies also reviewed for this report include: o Draff Dickson Drainage Investigation, Volume l, December 1992, R.W. Beck & Associates. This report examines the drainage system in the White Fence Ranch neighborhood downstream of the proposed project site in the May Creek Basin. o Windwood Technical Informarion Report, Revised June 11, 1999, Triad Associates. The Plat of Windwood is located adjacent to the west boundary of proposed Preliminary Plat of Maureen Highlands in the Cedar River Basin. Topoqraphic Information Topographic field survey data was collected by Hugh G. Goldsmith & Associates, Inc. for the plat site and adjacent areas including the downstream drainage system (Fall 2000/Spring 2001). 3-4 R99095-1340 Goldsmith& Associates Technicn!Information Reporr for the Plat of Maureen Highlands Task 3. Fie/d lnspection An inspection of the Maureen Highlands project site and downstream systems was conducted during the project topographic and wetland surveys (Fall 2000/Spring 2001) and again on February 2, 2001 and May 11, 2001. Inspections were completed using the guidelines for a downstream analysis as given in Section 2.3.1.1 of the 1998 KCSWDM. On the inspection data the weather was partly cloudy with scattered showers on February 2, 2001 and sunny and warm (70°F) on May 11, 2001. A Level 1 inspection was completed for the Cedar River Basin. A Level 3 inspection was completed for the May Creek Basin given that problems with localized flooding have been identified for this basin. Basin boundaries as shown on Exhibit 1 and 2 were verified, along with an examination of on-site and off-site drainage conditions and systems. Ground cover, slopes, soil types, wetlands and other topographic features were also observed. At the time of inspection on February 2, 2001 standing and flowing water was observed at various points in the downstream system. A detailed description of the drainage system and problems are presented in Task 4. 3-5 R99095-1.340 Goldsmith & Associates Teclti�icu!InJornta�io�t Report.jor rlte Plat oJ A4uuree�i Highlunds Task 4. Drainage System Description and Prob/em Descriptions The following gives a description of the drainage systems downstream of the proposed preliminary plat. This includes descriptions of both the May Creek and the Cedar River Basin systems. For further information refer to the following Off-site Analysis Drainage System Tables and Exhibit 1. Cedar River Basin As described previously, that portion of the site within the Cedar River Basin drains to the southwest. At the southwest property corner, site drainage combines with the N.E. 4'"Street ditch at a low point. At this low point drainage enters 12" diameter pipe. This pipe was constructed as part of the Plat of Windwood drainage system. This pipe conveys drainage along with drainage from a portion of the Plat of Windwood to the Windwood detention pond entering the pond at the southeast pond corner. The Windwood detention pond has been designed using the KCRTS Level 2 flow control standard (Windwood Technrcal Information Report, Triad, 1999). The Windwood pond discharges to a water quality swale before entering an 18" N-12 pipe. This pipe conveys drainage along the north side of N.E. 4t" Street before discharging to a rock-lined ditch approximately 600 feet to the west of the Maureen Highlands project site. This ditch continues to the west toward 148�'Avenue S.E. where it conveys drainage across N.E. 4`" Street (1,200 ft. downstream of site). Once the drainage crosses N.E. 4'h Street the downstream system continues to the west before heading south toward Stream 0307, a tributary of the Cedar River (one mile downstream). Stream 0307 forms a confluence with the Cedar River 9,000 feet (1.7 miles) downstream of the project site. The Cedar River drainage system show no signs of potential drainage problems. No erosion I problems or evidence of lack of conveyance capacity were observed. The system shows no signs of erosion or lack of conveyance capacity. Drainage control measures, in excess of KCRTS Level 2 Flow Control Standard, are not required. Mav Creek Basin As described in Task 1, site runoff within the May Creek Basin drains to the Plat of White Fence Ranch drainage system. The majority of the site drainage enters this downstream drainage system through the ditch along the east property line. A small amount of area drains to the White Fence Ranch system through the ditch along the north property line and by draining across Lots 28 through 32. Drainage from both areas converge at the 24"culvert crossing 156"'Avenue S.E. Runoff conveyed to the eastern ditch converges at the S.E. 124`" right-of-way. Drainage is then conveyed to the east by an open channel toward the east where it enters a closed pipe system through an 18" pipe. This closed pipe system conveys drainage east along S.E. 124"' Street towards 156�h Avenue S.E. before heading north. The closed pipe system is made of 18" concrete pipe. This pipe system, in addition to drainage from the project site, also conveys drainage from most of the Plat of White Fence Ranch as shown in Exhibit 1. Drainage sub- basins convey drainage to the S.E. 124"' system through mainly open ditches along 155`"Avenue S.E. and 156th Avenue S.E. These open ditches are separated by numerous driveway culvert 3-6 R9909�-1340 Goldsmith 8c ,4ssociates Tec�hnic�tl lnjonnarinn Repori Jnr the Plnt of Muureen Hi�h7nrrds crossings. Approximately 19 acres of White Fence Ranch drains to the S.E. 124"' system in addition to the 34 acres of the proposed Preliminary Plat of Maureen Highlands. Numerous flooding events have been reported along S.E. 124"'. This flooding is the result of inadequate conveyance capacity. The White Fence drainage system has been previously examined in the Draft Dickson Drainage lnvesfigation(R.W. Beck, December 1992). Based upon field gathered survey data, this pipe has segments that range in slope from -0.73% to 0.37%. Refer to Figure 5 for detailed pipe and topographic data for this storm drain system. The inverted sloped sections and the overall shallow slope of the pipe, together with the overall shallowness of the system combine to produce a poor system conveyance capacity. A detailed conveyance analysis of this drainage system is given at the end of this report section. The closed pipe system discharges to a ditch along the west side of 156"' Avenue S.E. before crossing the road through a 24" concrete pipe (Exhibit 2). This pipe discharges to a wetland area. This wetland drains to the east through Stream 0291 D. This stream is initially braided before entering a well defined channel. This channel has signs of excavation, particularly upstream of the 48" CMP bridge crossing. This bridge is used for a trail crossing of the stream. Downstream of this bridge the channel is natural in character. The channel is flat and wider and meanders through a gradually deepening valley before descending at a 5% slope to a valley bottom 2,800 feet east of White Fence Ranch and 700 feet upstream of the confluence of Streams 0291 D and 0291 A. The section of Stream 0291 D that descends to the lower valley shows signs of slight bank erosion. Once Stream 0291 D enters the valley bottom, the channel flattens and disperses through to a heavily vegetated wetland area before entering Stream 0291 A. Upstream of the confluence there are two existing detention facilities; Cemetery Pond and Doofer's Pond as shown on Exhibit 1. From this point to a point about 400 feet downstream, Stream 0291 A is 12 feet wide with standing water 1.5 to 2 feet deep. This channel is directly to the west of Coalfield Park. At the northwest corner of Coalfield Park, Stream 0291A enters a 48" N-12 drainage pipe beneath an access road for several single family homes. Exhibit 1 shows the basin boundary for the May Creek drainage basin upstream of the point of compliance for the Preliminary Plat of Maureen Highlands. At the point of compliance, the project area comprises 15% of the drainage area. S.E. 124"' Street Convevance Svstem Analysis The performance of the system, as described above, and as shown on Figure 5, has been assessed. A backwater analysis has been completed using runoff generated using the computer program KCRTS and the backwater anafysis spreadsheet from the KCSWDM (see Table II). Drainage from the White Fence Ranch sub-basins, as shown on Exhibits 2 and 3, were combined with runoff from the preliminary plat site and routed through the pipe system. The KCRTS regional rainfall factor was assumed to be SEATAC 1.0. The land cover data is based on actual land use. The following Table I gives the White Fence Ranch land cover data for each of the downstream system's tributary areas. These areas do not include the 33.8 acres of drainage area upstream of White Fence Ranch as shown on Exhibit 2. 3-7 R99095-1.340 Goldsmith&Associates Technical Information Report for the Plat of Maureen Highlands Table I White Fence Ranch - Sub-basin Data Total Area Till Grass Till Forest Impervious Area Source (ac.) (ac.) (ac.) (ac.) CB1 8.00 2.82 3.22 1.96 CB2 8.56 6.20 --- 2.36 C63 1.05 0.69 --- 0.36 C B4 1.94 1.25 --- 0.69 The runoff files for each of these tributary areas was combined with runoff from the plat site under current and proposed developed conditions and routed through the storm drain system. There is 33.8 acres of drainage area upstream of White Fence Ranch. This includes 30.5 acres of Maureen Highlands and 3.3 acres of off-site upstream area. This area under current conditions is modeled as Till Pasture. The KCRTS peak flow rates for both developed and the current conditions are given on the following pages. As shown in the backwater analysis there is inadequate conveyance capacity for the S.E. 124"' Street storm drain under the current drainage condition. Surcharging is indicated for the 2-year event. Under the proposed development condition, the amount of surcharge is slightly reduced. By implementing the stormwater control plan given in Task 5, localized flooding along S.E. 124`n Street will be slightly reduced. The proposed control plan reduces peak flow rates for up to the 10-year storm event to less than calculated for the site, assuming a forested site condition. This reduction in flow rates slightly raises the threshold event for which flooding occurs. Therefore, by implementing a control plan that utilizes the KCRTS Level 2 Flow Standard, under forested site conditions for calculation of allowable release rates and durations, exacerbation of downstream drainage problems will be prevented. 3-8 � R99095-1.340 Goldsmith & Ass-ociate� Technicnl lnJnrntcuiu�� Report jr�r tl�e P7nt��f,1�latereen Hi,�hlands �� OFF-SITE ANALYSIS DRAINAGE SYSTEM TABLE �� Surface Water Design Manual, Core Requirement #2 '� Basin: Cedar River Subbasin Name: Cedar River Subbasin Number: ----- Symbol Drainage Drainage Component Slope Distance Existing Potential Observations of field inspector Component Type, Description from site Problems Problems resource reviewer, or resident Name, and Size discharge see map Type: sheei flow,swale, drainage basin,vegetation cover,depth, % 1/4 mi=1,320 ft constructions,under capacity,ponding, tributary area,likelihood of problem,overflow stream,channel,pipe,pond; type of sensitive area,volume overtopping,flooding,habitat or organism pathways,potential impacis. EX.1 Size:diameter,surface area destruction,scouring,bank sloughing, ! sedimentation,incision,other erosion A 12"N-12 Pipe Sheel(low irom site combines with N.E.4'" •-- 0 Limited inlet capacity --- Low point 2-4"standing water St.drainage and enters Windwood system B Windwood Pond Inlet 12"pipe enters detention pond -�- 200 Erosion of inlet area --- ••••- C Pond Outlet Outlet of pond bio-swale --- 500 None ••- ----- D 18"N-12 Pipe Conveys drainage from pond along N.E. 3% 500•600 None --- ----- 4'" E 18"N-12 Day Lights Pipe discharges to rock lined ditch •-- 600 None •-- Ditch 18"deep 2-3'wide�2:1/5:1 side slopes F Roadside Ditch Ditch N.E.4'" 900 None --- Ditch widens and deepens G 30"Concrete Pipe Drain pipe crosses N.E.4°i 1,200 None --- -•--- H Ditch 30"pipe discharges to south road ditch 1,300 None --• ----- I 24"CMP Pipe drains to west discharging ditch 1,350 None --- ----- along south side of N.E.4"' J Ditch Drainage turns south 2,200 None --- Ditch area heavily vegetated Trib.0307 5,280 Cedar River 9,000 3-9 R99095-1.340 Goldsmith&Associates Teciinical/nfnrmatinrt Report,for the Plat qjMuureen Highlartds OFF-SITE ANALYSIS Vrs�►INAGE SYSTEM TABLE Surface Water Design Manual, Core Requirement #2 Basin: May Creek Subbasin Name: May Creek Subbasin Number: --- Symbol Drainage Drainage Component Slope Distance Existing Potential Observations of field inspector Component Type, Description from site Problems Problems resource reviewer, or resident , Name, and Size discharge see map Type: sheet flow,swale, drainage basin,vegetation cover,depth, % 1/4 mi=1,320 ft constructions,under capacity,ponding, tributary area,likelihood of problem,overflow siream,channel,pipe,pond; rype of sensitive area,volume overtopping,flooding,habitat or organism pathways,potential impacts. Ex.1 Size:diameter,surface area destruction,scouring,bank sloughing, sedimentation,incision,olher erosion A Ditch 18"culvert under N.E.4'"joins south end 1.5% 0 None --- • 6'wide,2'deep ditch of ditch along east property line • heavily vegetated � B Ditch North-south running ditch along east 0.5% 0 None 3'-4'wide,2'-3'deep property line C Ditch Primary site discharge,drains plat to 0% 0 Poorly graded --- Heavy vegetation/standing water White Fence Ranch 3'-4'wide,3'-4'deep D 18"Pipe Inlet to White Fence storm drain system --- 150 Silting of pipe -•- E 18"Pipe White Fence Ranch stoRn system varies 150•600 Flooding Increased flooding Limited conveyance cap;see analysis. I F 18"Pipe Outlet Piped system day lights to ditch --- 600 Silting of pipe --• 4"silt 7"standing water G Road Ditch Ditch on west side of 156"'Avenue S.E. 0.3% 600-1,000 None --- 3-4'deep;4-5'wide at bottom;6"standing water H 24"Culvert Culvert crossing to east side 156°i 0.25% 1,000 None --- ----- Avenue S.E. I DitchlChannel Discharge to wetland 1,050 None --- 12'wide narrows to 6';dirUgravel bottom(1• 2"water) J Channel Ditch widens to flat area 1,200 None --- 20-25'wide flat area 6"deep K Wetland 1,300 None ••• Wetland vegetation;4-6"wide channel;some channel braiding L Wetland 1,400 None -•- 3-4'wide channel;6"deep water;tall grasses '� 3-10 R99095-1.340 Goldsmilh& AssoeiAtes Tecl�nica(hi�ori�uuiuri Repart.fnr die Pla1 n/�Maure�iF Hi�;hlcuu(.c OFF-SITE ANALYSIS VrsHINAGE SYSTEM TABLE Surface Water Design Manual, Core Requirement #2 Basin: May Creek Subbasin Name: May Creek Subbasin Number: --- Symbol Drainage Drainage Component Slope Distance Existing Potential Observations of field inspector Component Type, Description from site Problems Problems resource reviewer, or resident Name, and Size discharge see map Type: sheei flow,swale, drainage basin,vegetation cover,depth, % 1/4 mi=1,320 fl constructions,under capacity,ponding, tributary area,likelihood of problem,overflow stream,channel,pipe,pond; type of sensitive area,volume overtopping,flooding,habitat or organism pathways,potential impacts. Ex.1 Size:diameter,surface area destruction,scouring,bank sloughing, sedimentation,incision,other erosion N Channel Channel upstream of bridge 1,600 None -•- 8-12'high bank;3-5'wide 0 48"CMP Culvert Bridge crossing --- 1,600 None -- Bridge(culvert)headwall,good condition P Channel Stream channel valley(natural channel) •-• 1,600-2,500 None --- Broad valley(40-50'wide),well vegetated, slight meander,fallen logs,6"water Q Channel Stream channel valley(natural channel) 5% 2,500 Potential erosion Increased erosion Channel steepens;rock/cobble;1-2'high bank,incised;some sloughing R Channel Valley ends,4'wide channel in 25'•30' --- 2,800 None None Signs of overtopping plain S Channel Braided channel through wetland plain --- 3,100 None None Overgrown with blackberries;poorly defined channel T 48"CMP Trail crossing at confluence with Stream --- 3,500 Silting 6-8'wide channel upstream,1-2'deep 0291A U Stream 0291A 12'wide channel;1.5-2'deep 3,500 None Channel follows edge of Coalfield Park V 48"N-12 Road crossing --• 3,900 None --- ----- May Creek Confluence --- 7,900 3-11 R')9095-1.340 Goldsini�h& Associates 7�eduiiccil l��fo��mn�ion Reparl for the l'!at uJ'Muuree�� HighltuiA,r 1 I � I " �' i��" � ' , _-_ �. �� .� �' ;_, ''�-_ _ _. �,E � s v � �I �E51263re ' , . ;° N rts,=�s _ Z:� ,,_ ,. , _. TO STREAM � � � 0291D `,\ r` � ^ siii I �� 1 .� I 1 z+ 1 . sie• I 1 � �� i Ij s�, '� �, 6 I �' r4 ` ` 0 SO 100; � � I ..�I�� sie' j�I I I = ��O' I rl�l ` 3�•' � _ �o \ I r I s._' � f I` �n I I i 1�� —� s��' WHITE FENCE RANCH I ;;1;'_, � —�` — _. �� a� ,,,. ,.s '- � OUTLET �• s MAUR EN � i -- �. T.� HIGHLA S �• I � I �� I ,_ - / :;,' -' � ° p ,.. i � I. �.,�,,.. _ ' � E M11 1� ��. \ pC � OJ E ' m _ .— — e_ . e'.p.c' a'c�� I � �„ � , " i � �.• r�,\j'Ci� , ��1�w6^��ri �� tbIY�TER Ep' —_ I•COIIC O ' (��.�'t ��s aser- _ '�[�i��-�I .C 12"1—F�7��i��i,L _ _ _ I i2'cY i � � �� _ �—�s_�r��-r e'na ' . �Y . � . — � � e�� 'r �`�T E12C511l3r/ re� <l�R� 3] GI Sl zI,UY � 'n �� 6Y.�. a� � E b'C�SN.)3 SM.51 CB RY SM�) CB 11N1 SM.)S E tl'C E 511.61 ROr[�111.�� F 'COIK li.lO � .-I� IE C'C N SN OS I E 12�C M SKJS _�e E RY S b�C M S'1.l3 ��- 4 � E N'C E lN.O � E IY 5 SN_�0 3 F 'C SE SK 33 1� 1 ��I IE 1!'C�=w_1) � �,�t �� ' ,�j � 'f � - � � —J.�i_: �,�• I ' 3 `�� , � �;� I � . I I �e �I j I: � I ( 1 T _. _` le � I �'. t�_ T III . .:�9 �1 I � ' . �� :.a � ' � v ` � �I �- � '�� ,\ . – D '\ I ��— T e I ! I r , n r � 7ni P�OTTED:99095E06.Arg MBARBE 03/19/02 i4: 8 J.W. MORRISON. INC. �oe No:99095 i T T � Hugh G. Goldsmith & Associates, Inc. 5�^�E: �••ioo' viEw: �� " � Consulting Engineers • Surveyors • Planners DATE: Jan 3�,zooz XREF: J DRAWN: MBARBER �SF: S.E. I 2 4 T H S T . � Bellevue4 11A 98004 SE oES��Eo: F�o eK: C 0 N V E Y A N C E S Y S T E M F I G. 5 � � P.O. Boz 3565 TFJ.: (425) 462-1080 a � Bellevue, 11A 98009 FAX: (425) 462-7719 APPROVE�: PG/: a ACAD DWG.: 99095xOB. r�SSF: RENTON WASHINGTON f Current Conditions: Peak Discharge at CB1 Flow Frequency Analysis Time Series File:cblex.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- -----Flow Frequency Analysis------- Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 3 .20 2 2/09/O1 15:00 5.84 1 100.00 0.990 1.49 7 1/05/02 16:00 3 .20 2 25.00 0.960 3 .16 3 2/28/03 3 :00 3 .16 3 10.00 0. 900 0.682 8 8/26/04 2:00 2.92 4 5.00 0.800 1.74 6 1/05/05 8:00 2.75 5 3 .00 0.667 2 .92 4 1/18/06 16:00 1.74 6 2.00 0.500 2.75 5 11/24/06 4:00 1.49 7 1.30 0.231 5.84 1 1/09/08 6 :00 0.682 8 1.10 0.091 Computed Peaks 4 .96 50_00 0. 980 Current Conditions: Peak Discharge at CB2 Flow Frequer,cy Analysis Time Series File:cb2ex.tsf Project Location:Sea-Tac I�I ---Annual Peak Flow Rates--- -----Flow Frequency Analysis------- Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 4.16 3 2/09/O1 15:00 8.26 1 100.00 0.990 2.27 7 1/05/02 16:00 4.54 2 25.00 0.960 4.54 2 2/27/03 7:00 4.16 3 10. 00 0.900 1.38 8 8/26/04 2 :00 4.11 4 5.00 0 .800 2 .42 6 1/05/OS 8:00 3 .83 5 3.00 0.667 4.11 4 1/18/06 16:00 2 .42 6 2.00 0.500 3 .83 5 11/24/06 3:00 2 .27 7 1.30 0.231 8.26 1 1/09/08 6:00 1.38 8 1.10 0.091 Co:n�uted Peaks 7 . 02 50.00 0 .980 3-13 R�I91)9>-I.;.i(�Goldsmi�h c� Associates Te�'Jr��iral l+ijormatinn Repnrt(ur�he Pl�u oj�tlenueen Hi�;hlunds Current Conditions: Peak Discharge at CB3 Flow Frequency Analysis Time Series File:cb3ex.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- -----Flow Frequency Analysis------- Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 4.29 3 2/09/O1 15:00 8.59 1 100.00 0.990 2 .39 7 1/05/02 16:00 4.72 2 25.00 0.960 4.72 2 2/27/03 7 :00 4.29 3 10.00 0.900 1.49 8 8/26/04 2:00 4.26 4 5.00 0.800 2 .51 6 1/05/05 8:00 3 .98 5 3.00 0.667 4.26 4 1/18/06 16:00 2.51 6 2.00 0.500 3 .98 5 11/24/06 3 :00 2.39 7 1.30 0.231 8.59 1 1/09/08 6:00 1.49 8 1.10 0.091 Computed Peaks 7 .30 50.00 0.980 Current Conditions: Peak Discharge at CB4 Flow Frequency Analysis Time Series File:cb4ex.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- -----Flow Frequency Analysis------- I Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 4.52 4 2/09/01 15:00 9 .18 1 100.00 0.990 2.60 7 1/05/02 16:00 5.06 2 25 .00 0.960 5.06 2 2/27/03 7:00 4.56 3 10.00 0 .900 1.69 8 8/26/04 2 :00 4.52 4 5.00 0.800 i 2 .68 6 1/05/05 8:00 4.25 5 3 .00 0.667 4.56 3 1/18/06 16:00 2.68 6 2 .00 0. 500 4.25 5 11/24/06 3:00 2 .60 7 1 .30 0 .231 9.18 1 1/09/08 6:00 1.69 8 1.10 0.091 Computed Peaks 7 .81 50.00 0.980 3-14 R99(ly�-l.��10 Goldcmrth & Associates Terhntrul hil�+rmcrti�m Report jnr the Plnt oj dluureeri Hi,lhkuzd.r Developed Conditions: Peak Discharge at C61 Flow Frequency Analysis Time Series File:cbldev.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- -----Flow Frequency Analysis------- Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 2.64 2 2/09/01 18:00 4.67 1 100.00 0.990 0.947 6 1/05/02 16:00 2 .64 2 25.0� 0.960 2.16 4 3/06/03 18:00 2.21 3 10.00 0.900 0.854 8 8/26/04 2:00 2 .16 4 5.00 0.800 0.936 7 1/05/05 8:OQ 1.52 5 3. 00 0.667 1.52 5 1/18/06 21:00 0.947 6 2.00 0.500 2 .21 3 11/24/06 4:00 0.936 7 1.30 0.231 4.67 1 1/09/08 10:00 0.854 8 1.10 0.091 Computed Peaks 3 . 99 50.00 0.980 Developed Conditions: Peak Discharge at C62 Flow Frequency Analysis Time Series File:cb2dev.tsf Pro;ect Location:Sea-Tac ---rnnual Peak Flow Rates--- -----Flow Frequency Analysis------- Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 3.53 2 2/09/O1 15:00 5 .52 1 100.00 0.990 1.74 6 1/05/02 16:00 3 .53 2 25.00 0.960 3.12 4 3/06/03 18:00 3 .26 3 10.00 0.900 1.56 8 S/26/04 2 :00 3 .12 4 5.00 0.800 1.71 7 10/28/04 16:00 2 .50 5 3.00 0.667 2.50 5 1/18/06 16:00 1.74 6 2.00 0.500 3.26 3 11/24/06 4:00 1.71 7 1.30 0.231 5.52 1 1/09/08 10:00 1.56 8 1.10 0.091 Computed Peaks 4 .85 50.00 0.980 3-15 R99095-1340 Goldsmith &Associates Technicul lnfi�rmntron Repor�.(or the Plat qjMaureen Hrghlands Developed Conditions: Peak Discharge at CB3 F'�o•.v r Yequency =.nal�%s,�s Time Series File:cb3dev.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- -----Flow Frequency Analysis------- Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 3 .65 2 2/09/O1 15:00 5.76 1 100.00 0.990 1.84 6 1/05/02 16:00 3 .65 2 25.00 0.960 3.24 4 3/06/03 18:00 3 .40 3 10.00 a.900 1.66 8 8/26/04 2 :00 3 .24 4 5.00 0.800 1.84 7 10/28/04 16:00 2 .66 5 3 .00 0.667 2.66 5 1/18/06 16:00 1.84 6 2.00 0.500 3 .40 3 11/24/06 4:00 1.84 7 1.30 0.231 � 5.76 1 1/09/08 8:00 1.66 8 1.10 0.091 Computed Peaks 5. 06 50. 00 0.980 Developed Conditions: Peak Discharge at CB4 Flow Frequency Analysis Time Series File:cb4dev.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- -----Flow Frequency Analysis- Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 3.89 2 2/09/O1 15 :00 6.34 1 100. 00 0.99u 2.05 7 1/OS/02 16:00 3 . 89 2 25 .00 0.95C 3.48 4 3/06/03 18:00 3 .66 3 10.00 0.9C=; 1.86 8 8/26/04 2 :00 3 .48 4 5.00 0. 8: 2 .08 6 10/28/04 16:00 2 .96 5 3 .00 O. E 2.96 5 1/18/Q6 16:00 2.08 6 2 . 00 0. � 3 .66 3 11/24/06 4:00 2 . 05 7 1 .30 0.� 6.34 1 1/09/08 6:00 1.86 8 1.10 0. � Computed Peaks 5 .53 50. 00 0. 5� 3-16 R99095-1340 Goldsmith&Associates Technical Injnr-matlon Report.for the Plat of Maureen Highlands Table II EXISTING CONDITIONS-SE 124TH STREET STORM DRAIN SYSTEM Backwater Calculation Sheet 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Barrel Entr. Entr. Exit Outlet Inle� Appr. Bend Junc. Pipe Pipe Outlet Inlet Barrel Barrel VeL TW Friction HGL Head Head CoNrol Conrol Vel. Head Head HW Ground Segment 0 Length Size 'n' Elev. Elev. Area Velociry Head Elev. Loss Elev. Loss Loss Elav. Elev. Head Loss Loss Elev. Elev. DifL CE3 to CB (cfs) (fl) (in) Value (fl) (ft) (sq ft) (Ips) (R) (ft) (fl) (ft) (tq (ft) (ft) (ft) (it) (fq (fQ (ft) (R) (ft) Outlet CB5 2.68 95.0 18 0.013 513.98 514.13 1.77 1.52 0.04 515.48 0.06 515.63 0.02 0.04 515.68 515.23 -0.04 0.00 0.00 515.65 51823 2.58 CBS CB4 2.68 110.0 18 0.013 514.19 514.33 1.77 1.52 0.04 515.65 0.07 515.83 0.02 0.04 515.88 515.43 •0.03 0.04 -0.01 515.89 518.43 2.54 Cf34 C83 2.51 140.0 18 0.013 514.4B 514.67 1.77 1.42 0.03 515.89 0.08 516.17 0.02 0.03 51622 515.75 -0.03 0.00 •0.01 516.18 516.57 0.39 CB3 CB2 2.42 144.0 18 0.013 514.57 514.44 1.77 1.37 0.03 516.18 0.08 516.26 0.01 0.03 516.30 515.52 -0.02 0.00 0.00 516.28 514.33 -1.95 I CB2 CB1 1.74 41.0 18 0.013 514.33 514.03 1.77 0.99 0.02 51628 0.01 51629 0.01 0.02 516.32 515.08 0.00 0.00 0.00 516.32 518.35 2.03 DEVELOPED CONDITIONS-SE 124TH STREET STORM DRAIN SYSTEM Backwater Calculation Sheet 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Barrel Enir. Entr. Exit Outlet Inlet Appr. Bend Junc. Pipe Pipe Outlet Inlet Barrel Bairel Vel. TW Friction HGL Head Head Control Conrol Vel. Head Head HW Ground Segment Q Length Size 'n' Elev. Elev. Area Vetocity Head Elev. Loss Elev. Loss Loss Elev. Elev. Head Loss Loss Elev. Elev. Dift. CB to CB (cis) (it) (in) Value (ft) (it) (sq R) (ips) (ft) (A) (ft) (tt) (iQ (ft) (ft) (ft) Qt) (ft) (fQ (it) (it) (iq Outlet CBS 2.08 95.0 18 0.013 513.98 514.13 1.77 1.18 0.02 515.48 0.04 515.63 0.01 0.02 515.66 515.19 -0.02 0.00 0.00 515.64 51823 2.59 CB5 C84 2.08 110.0 18 0.013 514.19 514.33 1.77 1.18 0.02 515.64 0.04 515.83 0.01 0.02 515.86 515.39 -0.02 0.02 0.00 515.86 518.43 2.57 CB4 CB3 1.84 140.0 18 0.013 514.48 514.67 1.77 1.04 0.02 515.86 0.04 516.17 0.01 0.02 51620 515.72 -0.02 0.00 0.00 516.18 516.57 0.39 CB3 CB2 1.74 144.0 18 0.013 514.57 514.44 1.77 0.99 0.02 516.18 0.04 51622 0.01 0.02 516.24 515.48 0.00 0.00 0.00 516.23 514.33 -1.90 CB2 CB1 0.95 41.0 18 0.013 514.33 514.03 1.77 0.54 0.00 516.23 0.00 516.24 0.00 0.00 51624 515.05 0.00 0.00 0.00 516.24 518.35 2.11 3-17 R9')095-1.340 Goldsmi�h & Associules Technicnl In(nrm�Uiun Repart,(ui�die PInI a/Mcuu-een Highln�id.c Task 5. Mitigation of Existing or Potential Problems I� In the previous section the only potential drainage problem identified was the portion of the downstream drainage system in the Plat of White Fence Ranch. This system has in the past ', caused localized flooding problems along S.E. 124t'' Street. A stormwater control plan has been ' developed for the Preliminary Plat of Maureen Highlands that will prevent the exacerbation of this , downstream problem. ' Section 4 of this Technical Information Report (TIR) presents the drainage control plan including detailed hydrologic calculations for both the Cedar River and the May Creek drainage basins. The proposed control plan has been developed in accordance with the requirements of the City of Renton Development Regulations and the 1998 KCSWDM. In addition to these documents' requirements, additional control measures are proposed for the May Creek Basin. These . additional measures address the limited conveyance capacity of the downstream drainage system. Existing and developed site hydrology has been modeled using KCRTS methodology Exhibit 2 shows the existing conditions of the site. Exhibit 3 shows the developed condition: '�, basin plan including the location of the proposed flow control facilities. Please note the followinc ', assumptions were made as part of the development of the drainage control-plan. It is assumec I that for the calculation of existing runoff conditions for both the Cedar River and May CreeF !� Basins the site is 100% forested even though the site has been cleared. This assumption is ir '� accordance with the 1998 KCSWDM requirements that the condition of the site in 1979 is to bE, used for establishing existing or natural conditions. A second assumption made is that all roo� I drains are directed toward the proposed detention facilities. Assuming all drainage is directed tc the detention ponds without attenuation through the wetlands results in the conservative sizinc of the proposed detention. It should be noted that wetland hydrology will be maintained b` .J;,. ...�t.-.r. „.. , . ,.,..-,.-�..+.-. .,��,-.,h n. ,-.f .-,�(.f ,-!. . .,� rl�,n,.�+I�� +., +h!, � .,+I-,�-,�-7 3-18 R99095-].340 Goldsmith& Associates Tecla�icul L�jonrzrrtinn Report/or the Plat qf,�Taureen Highlaitds 4. F/ow Control and Water Quality Facility Analysis and Design Part A: Existing Site Hydro/ogy Existing site hydrology has been modeled using the King County hydrologic program KCRTS. Exhibits 1 and 2 shows the existing drainage conditions for Maureen Highlands and surrounding area. The developed basin boundaries and the location of the proposed flow control facilities are shown on the enclosed Exhibit 3 as described in Part B. The following is a summary of the existing state hydrologic input parameters and the basin areas used for calculating the allowable facility release rates and durations used in design of the proposed stormwater plan for Maureen Highlands. KCRTS Input Parameters: Regional Rainfall Scale Factor = SeaTac 1.0 (KCSWDM Fig. 3.2.2.A) Time Step = 1.0 Cedar River Basin: The following land surface cover information was used for calculation of the existing condition runoff for the portion of the project site within the Cedar River Basin. This is the area used for establishing allowable release rates and durations. The existing basin area includes 0.62 acres of N.E. 4`h Street and frontage area. As per the 1998 KCSWDM the land cover condition that existed in 1979 governs the calculation of allowable release rates. Since the site was cleared in 1989 the site has been assumed to be forested for establishing pond release rate flows and ' durations. ' Existing Basin Area = 4.86 Ac. ! Impervious Area = 0.47 Ac. (N.E. 4"' Street frontage) I Till Pasture = 0.19 Ac. (grassed area along N.E. 4`h Street) ' Till Forest = = 4.07 Ac. I Existing Conditions (Forested) Peak Runoff Rates: ' Flow Frequency Analysis Time Series File:exced.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- -----Flow Frequency Analysis------- Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob ; (CFS) (CFS) Period i 0.346 2 2/09/01 15:00 0.536 1 100.00 0.990 i 0.172 7 1/05/02 16:00 0.346 2 25.00 0.960 0.321 3 2/28/03 3 :00 0.321 3 10.00 0.900 0.118 8 8/26/04 2:00 0.313 4 5.00 0.800 0.193 6 1/05/OS 8:00 0.287 5 3.00 0.667 0.313 4 1/18/06 16:00 0.193 6 2.00 0.500 0.287 5 11/24/06 4:00 0.172 7 1.30 0.231 0 .536 1 1/09/08 6:00 0 .118 8 1.10 0. 091 Comp•sted ?eaks C . 4�3 �0 . 00 0 . 98Q i 4-1 � R99095-1340 Goldsmith& Associates Tecluucnl L�fnrmarrun Reprmt fnr N�e Plar uf,'Lfuureen Nighlruids Mav Creek Basin: The following land surface cover information was used for calculation of the existing condition runoff for the portion of the project site within the May Creek Basin. This is the area used for establishing allowable release rates and durations from the project site and includes 3.3 acres of off-site area as shown on Exhibit 2. As per the 1998 KCSWDM the land cover condition that existed in 1979 governs the calculation of a allowable release rates. Since the site was cleared in 1989 the site has been assumed to be forested for establishing pond release rate flows and durations. For calculating existing conditions release rates, the existing basin area does not include the tract containing Wetland B. This tract will remain undeveloped and will continue to drain to the eastern ditch following development and is, therefore, not included in the calculation of existing release rates or pond inflows. Existing Basin Area = 34.23 Ac. Wetland = 0.62 Ac. (Wetland D and buffer area) Till Forest = 33.61 Ac. Existing Conditions (Forested) Peak Runoff Rates: I Flow Frequency Analysis Time Series File:mayex2 .tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- -----Flow Frequency Analysis------- I Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) {CFS) Period , 2 .18 2 2/09/O1 18:00 2 .82 1 100.00 0.990 0.582 7 1/06/02 3 :00 2.18 2 25.00 0.960 1.64 3 2/28/03 3:00 1.64 3 10.00 0.900 0.056 8 3/24/04 20:00 1.63 4 5.00 0.800 0.940 6 1/OS/05 8:00 1.37 5 3.00 0.667 1.63 4 1/18/06 21:00 0.940 6 2 .00 0.500 1.37 5 11/24/06 4:00 0.582 7 1.30 0.231 2.82 1 1/09/08 9:00 0.056 8 1.10 0 .091 Computed Peaks 2 .61 50.00 0.980 4-2 R99095-1340 Goldsmith& Associates Technical/nformalion Report for d�e Plut ajMauree�t Highfands Part B: Deve/oped Site Hydro/ogy As with the existing conditions the developed site hydrology is modeled using KCRTS. Exhibit 3 shows the developed drainage conditions for the Maureen Highlands. This exhibit includes the developed basin boundaries, the proposed detention pond locations and the conveyance system layout. The following is a summary of the developed state basin areas used for calculating the pond inflow and bypass runoff rates and durations. Cedar River Basin: The developed conditions drainage area draining directly to the proposed detention pond and the area bypassing the facility have the following land surface cover breakdown. The developed basin area includes both site development and frontage improvements for N.E. 4"' Street Total Developed Basin Area = 4.86 Ac. (includes on and off-site areas) Area Draining to Pond Impervious Area: Roads = 1.38 Ac. (Including N.E. 4`h frontage improvements) 13 Lots x 4,000 S.F./lot = 1.19 Ac. Pond Surface = 0.33 Ac. Total Impervious Area = 2.96 Ac. Pervious Area: '�I Till Grass = 1.62 Ac. Total Pond Basin Area = 4.58 Ac. Developed Conditions Peak Detention Pond Intlow Rates: Flow Frequency Analysis Time Series File:inced.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- -----Flow Frequency Analysis------- Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 0.863 6 2/09/O1 2:00 1.74 1 100.00 0.990 0.706 8 1/05/02 16:00 1.12 2 25.00 0.960 1.04 3 2/27/03 7 :00 1.04 3 10.00 0.900 0.768 7 8/26/04 2:00 0.924 4 5.00 0.800 0.924 4 10/28/04 16:00 0.916 5 3 .00 0.667 0.916 5 1/18/06 16:00 0.863 6 2 .00 0.500 1.12 2 10/26/06 0:00 0.768 7 1.30 0.231 1.74 1 1/09/08 6:00 0.706 8 1.10 0.091 Computed Peaks 1.53 50.00 0.980 4-3 R9909S-�.340 Goldsmith& Associates Technicu!Irifnrmution Repnrt fnr the Plcit q(Maureen Higltfa�tds Pond Bypass Area: Impervious Area N.E. 4`h frontage Area = 0.14 Ac. Road C = 0.14 Ac. Total Bypass Area = 0.28 Ac. Developed Conditions Bypass Area Peak Runoff Rates: Flow Frequency Analysis Time Series File:bypced.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- -----Flow Frequency Analysis-�----- Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 0.068 7 2/09/O1 2 :00 0.132 1 100.00 0.990 0.060 8 1/05/02 16:00 0.101 2 25.00 0.960 0.083 3 12/08/02 18:00 0.083 3 10.00 0.900 0.070 6 8/26/04 2:00 0.083 4 5.00 0.800 0.083 4 10/28/04 16:00 0.072 5 3 .00 0.667 0.072 5 1/18/06 16:00 0.070 6 2.00 0.500 0.101 2 10/26/06 0:00 0.068 7 1.30 0.231 0.132 1 1/09/08 6:00 0.060 8 1.10 0.091 Computed Peaks 0.122 50.00 0.980 Mav Creek Basin: The developed conditions drainage area draining directly to the proposed detention pond has the following land use breakdown. The developed area includes 3.3 acres of off-site area modeled as till pasture and 1.4 acres of area bypassing the May Creek Detention Pond. The bypass area is comprised of the back 20 feet of the lots along the east boundary south of the May Creek detention pond and the 30 foot drainage easement. Developed Basin Area = 33.47 acres Surface Cover: Impervious Area: Roads = 6.68 Ac. 105 Lots x 4,000 S.F./lot = 9.64 Ac. Pond Surface = 2.34 Ac. Total Impervious Area = 18.66 Ac. Pervious Area: Till Pasture = 3.3 Ac. (off-site area) Till Grass = 9.71 Ac. (Includes 6 Lots discharging to wetlands) Wetland = 0.40 Ac. Total Pervious Area = 13.41 Ac. Total Basin Area = 32.07 Ac. a-a R99095-1340 Goldsmith&Associates Technica!lnformation Report for the Plat of Maureen Highlands Developed Conditions Peak Runoff Rates to Detention Pond: Flow Frequency Analysis Time Series File:maydev3.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- -----Flow Frequency Analysis------- Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 5.62 6 2/09/O1 2:00 11.26 1 100.00 0.990 4.52 8 1/05/�2 16:00 7.03 2 25.00 0.960 6.72 3 2/27/03 7:00 6.72 3 10.00 0.900 4.84 7 8/26/04 2:00 5.92 4 5.00 0.800 I 5.83 5 10/28/04 16:00 5.83 5 3.00 0.667 i 5.92 4 1/18/06 16:00 5.62 6 2.00 0.500 7.03 2 10/26/06 0:00 4.84 7 1.30 0.231 11.26 1 1/09/08 6:00 4.52 8 1.10 0.091 Computed Peaks 9.85 50.00 0.980 Pond Bypass Area: Till Grass = 1.4 Ac. Developed Conditions Bypass Area Peak Runoff Rates: Flow Frequency Analysis Time Series File:maybyp.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- -----Flow Frequency Analysis------- Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 0.364 7 2/09/O1 2:00 0.709 1 100.00 0.990 0.320 8 1/05/02 16:00 0.545 2 25.00 0.960 0.444 3 12/OB/02 18:00 0.444 3 10.00 0.900 0.374 6 8/26/04 2:00 0.444 4 5.00 0.80G 0.444 4 10/28/04 16:00 0.389 5 3.00 0.667 0.389 5 1/18/06 16:00 0.374 6 2.00 0.500 0.545 2 10/26/06 0:00 0.364 7 1.30 0.231 0.709 1 1/09/08 6:00 0.320 8 1.10 0.091 Computed Peaks 0.654 50.00 0.980 Part C: Performance Standards Flow Control Standard Both the May Creek and Cedar River basin detention ponds have been designed to follow the City of Renton Development Regulations and the requirements of the KCRTS Level 2 Flow Control standard as per the 1998 KCSWDM. Conveyance System Capacity Standard Maureen Highlands follows the requirements for new systems as per the City of Renton Development Regulations and the 1998 KCSWDM 1.2.4. Water Quality Menu The proposed detention ponds both utilize a combined detention / wetpond water quality control facility. 4-5 R99U95-1340 Goldsmith &Associates Teclinicul Ir{jorn:atinn Report Ji�r tlre Plut of,Llnureen Highlunds Part D: F/ow Contro/ System Stormwater control for Maureen Highlands is to be provided by two combination detention / wetponds located in either the Cedar River or May Creek drainage basins. The following gives detailed information related to the design of the proposed detention ponds including pond inflows and discharge rates. Cedar River Drainaqe Control Plan: Developed conditions drainage will be directed to a combined detention/water quality pond. This pond is located in the southwest corner of the property and will drain to the existing Plat of Windwood drainage system as shown on Exhibit 3. The Cedar River pond has been sized using the KCRTS Level 2 flow control standard. The Level 2 standard maintains developed pond discharges at or less than the existing peak rates for the 2-year and 10-year events. In addition, flow durations between 50% of the 2-year and the 50-year event must match existing conditions flow durations. The following gives details of the pond design and the pond peak discharge rates along with a flow duration comparison. Based on the following, the KCRTS Level 2 criteria has been met. The proposed Cedar River pond is shown on Figure 6. The pond outlet control structure is shown on Figure 7. Refer to Figure 8 for a comparison of flow durations under both existing and developed conditions. Pond Design Summary: Required Detention Volume = 1.12 ac.-ft. Cedar River Facility Detention Stage-Storage Table Elevation (ft.) Area(sf) Volume(cf) Cumulative Volume(cf) , 511.0 5781 0 0 I' 512.0 7030 6406 6,406 ; 514.0 9742 16,772 23,178 516.0 12,756 22,498 45,676 ' 517.0 14,378 13,567 59,243 Designed Detention Volume = 1.36 ac.-ft. (21% F.S) I Pond Surface Data Pond Bottom = 506.00 W.Q. W.S. = 511.00 Max. W.S. = 517.00 Berm Elev. = 518.50 4-6 R99095-1340 Goldsmith& Associa[es Technical/nforn:ation Reporr firr the Plu�of Maureen Highlands Orifice Sizing Table: Orifice Diameter Elevation 1 1.25 509.00 ft. I 2 1.90 514.90 ft. I 3 1.75 515.60 ft. I Pond Outlet Elevation = 511.00 ft. Riser Elevation = 516.80 ft. Riser Diameter = 12 inches The following KCRTS pond document file gives the pond peak discharge rates (summarized below) and a comparison of existing and developed flow durations Cedar River Detention Pond Discharge Rate Comparison Flow Rate (cfs) Event Existing (forested) Developed 2-year 0.193 0.134 10-yea r 0.321 0.309 a-� R99095-1.340 Goldsmith& Associates Terh�tia�f Infonrtatimi Repart Ji�r the Pltit o(Alaureen Higlilar�ds i , I **N �E. B PORTIO OF THE E. I/2 OF SEC. II TW . 2 . R ��E., W.M. � ;� ' � ' e ,;,INTERIOR POND SIDE SLOPES,IOENTIFIED - � � ', g 'AS'�S:I(MAX.J',ARE SHOWN AT 3.25:1 � I � , LEGEND: I '� � I T.0 ALLOW FOR SUGHT YARIABIUTY I ' � �� / � . a � i � � DURIN�i CONSTRUCTION.TOP OF SLOPE . . . I IZ3! `,p� . Sf�OULD BE HELD IN ALL CASES TO I � � � � � � . � � . . - i � � N ! � MAINTNN POND VOLUME ,:�,'�J _ � .� . . 15 GRAVEL.ACCESS R04�. ' CB,}D-I TYPE II-54' I ,� TYPE I CATCH BASIN - �c �ELEV.=510.50� `. A. W/SPIL�.CONTROL i'I� N ,r�� O TYPE II CATCH BASIN i � I , � , '� I ' � � � W/SOLID LOGKING L D {� M�+ �\ 6'PVC ROOF DRAIN OVERFLOW STRUCTURE j�l . . . . . . . _� .� I � � I� 'I RtM= 52L40 � I�' ', h �� N.5 y W/CLEANOUT V Q 48"�YP�II CB � - . , I� a � � - STORM DRAIN PIPE W/BIRDCs1GE TOP i � IE IB"-514.22 •.�I � , � I I rsEe sryr.s-za� f '�i �� fl N J Z RIM E'LEVq=517.5� - / �s:� 0, 6.y4 I . � I� �+ N � � FINISHED GRADE CONTOUR - J Q IE 12"°-51PA2 . � � - - Fta�" . ,�� p. � :-.� . SEE S�T.5,-24 A �i � e�, � . � � 1 � � - EXIST.GROUND CONTOUR �� J I il9 4�F ' ' ' � ' ' ' . ��pG�� P ] �.a CEDAR RIWER STORMW�4TER FACILITY; ' � i� �� G � i � � � �12'IN-i o - �� yEu �� , ti � I� C MBIN �DET NTI N WATER UALITY W�TPO '� � � �H Y•.- , � ROCKERY�HEIGHT IN FEET) � g Z Z " � � . i o �.0 z �' ,r 'GRP L� Q I1 � V �I i �� W . � GABION WALL W CB fF'$ Tl{PE 11'48' � i � � m , �5�� S 15 � r! POND BOT M•506. 0 ' �� ' - � � W/ SOLID LQCKING LID � 3:I(M X.)y :o � • . WATER OUAUTY W.S.•SIL � ' �� a 'i � F- � RIM=518.501 � L '�, I � �ry I� �� pj� q_ ' SANITARY SEWER SHOWN N = PONO BOTTOM 100 YR.W.S.�517.00 v� � - IE 12"_�07.p4 � � � I� � �i > FOR REFERENCE � 15 LF 12" � � i24 p z. SECTION q- 506.00 �'� I OVERFLOW W.S. •517.43 , Q �P � I N-12 e 1.70% � �N-� o�3 �1 � A �,�0�-�. � . � EMER.OYERFLOW W.S.�51T73 �- ,�� I 3y N�� . �. Z z I �UN�ER Ep � 0 �-N5�� -�. :I AX * � BERM ELEV.�518.50 I ' . y I� I ; OW q ��y - - w I ! �- v i � . O �. I l 1 I � �� E I� ��" REOUIRED DETENTION OLWME-1.12 Ac F1. r� �� '� cuWi � r w ,I C O N T R O L S T R�I C T U R 6�l I , � i � I� � J I 2`� � ' �� ' S4"7rPE N C6 < i i i I � aP . i DESIGN DETENTION V U M E=1.3 6 Ac.F i.i _ �� y _ � i � I i S •S�I.O IE 12"=509.0� ! REQUIRED W.Q.VOLUAA�=0.36 Ac.Fi. � , � Y � g I "� W/ JAILH011SE WINDOW �-� � N c J � " OPENING ELEV�= 517.00 I ' . . I . , �� DESIGN W.O.VOLUME-0.3�7 Aa Ft. 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I .. : .: ... . . ._ . .i .. . . . _ -- V x ��\,�r � � I � � � � : � s : . : .: ..�I ...: .... .... ..... :�.: :�.. �. �. :�. .� : : : �.�. . -. :�. : : . :: .:: . NAV6198B PER CiTY GP RENTON ��.o �,� A Sf.,�e � �� - � : � �� . - CONTROL POINT IB52 � +t �eg ��m ^ : ,. .. . _ .. t ... . .... p p °� :. ..:. j: .:: : .: :�. .�.: C��.EDI R�.��.RI E�.R POND: ..:�.:� :�.:.: .�.::.. .�:: �:�.. -: :�. : I� : �.: CEDAR :RI ER TiONQ :_. �.�. .� " MONUMENMAT�INTERSECTONDF . ��y �� ' �S� .. ......:.�.-:::�.:�. :�.: �_ :� ........ ..�. . . . ......... ...... . ... . .. , .:. . .. .. . . _ ..... .. ._ . . r . . . .. 4TH STREET (S.E.128TH STREETJ A� <P .. . .............. ....�.. . ..�: :�..- . �,�.. . :- : :�::�.. :::�.::.: ��.:-: ' . :�...�. . ... . . . ._ . . . ..... . .. . ._ . .. S E�+T I . B -i��.B .. . .. ... . .... - 148TH AVENUE S.E. tITY OF EN70�: sMeer '' �r '.: :': .:�. : :.�.: : :.: .�.S�CTIO . A .A. .. .. . . . .. �:�. .� �. . -. . .. .:�. ::O • ��. I .".. ... _ . . .� CONTROLPOINT1852 : ..... .. _�. : . ...._ ._ ��. .::: " :.: j :�.-.-.: .�.. . .... _. ,_�. � :. : �-: .._ .:: �::�. :�.� .: : .. . "�_ .-::�. � ..:.: ELEVATION� 454.77 N ' 19 5-2 3 - : -.�. : ._ �. :.. :�i ,:: _.. . .. i -. _ . .. .. . :.. . II�. � . :I: . _ ��. . ... .. .. . . _ . . ... .. . * A�DITIONAL SURV CO L NOTES .�oe No.: 99095-I z` � . . .� .� -. -� . . . ', . .. .ii .. .. .. .. . . . - LOCATED ON SHE �� z �. :-. : - . '�i . .:- j :�. ... I .. . ..� .... ... I :: �. .:�. �I �. : :I .�.�: ��i �.� �._� ��. -�. i : �. �.: �.. �:i �� I_ ROUND SOLID COVER WITH LOCKING BOLTS SEE C.O.R_ DWG NAME BR2� SOLID LOCKING LID ELEV. = 519.20 SEE SHT 8-14 OVERFLOW NOTCH WEIP (VERTICAL BAR GRA7E'r CONTROL TEE � H=1.0�; L=3.53� =90° PER C.O.R. DWG BR04 < SEE SHT 5-31 EMERGENCY OVERFLOVd i �� W.S. = 517.73 � 100 YR. W.S. = 517 G�� TOP RISER ELEV. = 516.80 c i ORIFICE NO. 3, INV. = 515.60 � ELBOW (TYP) ORIFICE DIA.=1.75" PER C.O.R. DwG "JAPr1E BRO� � ORIFICE PLATE WELDED TO SEE SHT 5-31 I 6° CMP ELBOW ��\ 12�� RISER ORIFICE N0. 2, INV. = 514.90 �� V` iJ ORIFICE DIA.=1.90" f � IP T ORIFICE PLATE WELDED Tfl 1'� P E SUPPOR � 6�� CMP ELBOW PER C.O.R. DWv P!�'i'v1= �NC;c SEE SHT 5-31 FRAME a LADDER OR STEPS � CATCH BASIN SEE C.O.R. SP PG. B035 � j -"P= II-5- ' SEE SHT 5-29 N� N� 12" OUT �� !2"IN - 15 L�7� % INVERTED FROM POND I E. = 511.00 I.E. = 51I.00 ORIFICE N0. I, EL=509.00 ,� CLEANOUT GATE: SH�AR GATE ORIFICE DIA.=1.25" WITH CONTROL ROD, SEE C.O.R. DWG NAME BR05 ScE SHT 5-31 RESTRICTOR PLATE PER C.O.R. DWG NAME BR04 SEE SHT 5-3I BOTTOM ELEV. = 507.00 y � :, � - PROFILE CEDAR RIVER POND OUTLET CONTROL STRUCTURE # I , TYPE II - 54 " SCALE: N.T.S (P E R C.0.R. S T D D R�;'��'a`I`��,1�� ,R��`; �-E _—'T _ -- FIGURE 7 Cedar River Basin Pond Retention/Deten��on Facility Type of Facility: Detention Pond Side Slope: 3 .00 H: 1V Pond Bottom Length: 100.00 f� Pond Bottom Width: 50.00 fc Pond Bottom Area: 5000. sa. ft Top Area at 1 ft. FB: 12785 . sq. ft 0.293 acres Effective Storage Depth: 5.80 ft Stage 0 Elevation: 0.00 ft Storage Volume: 46479. cu. ft 1.067 ac-ft Riser Head: 5.80 ft Riser Diameter: 12 .00 inches Number of orifices: 3 Full Head Pipe Orifice # Height Diameter Discharge Diameter (ft) (in) (CFS) (in) 1 0.00 1.25 0.104 2 3.90 1.90 0.142 4.0 3 4.60 1.75 0.098 4. 0 Top Notch Weir: None Outflow Rating Curve: None Stage Elevation Storage Discharge Percolation Surf Area (ft) (ft) (cu. ft) (ac-ft) (cfs) (cfs) (sq. ft) 0. 00 0.00 0. 0.000 0.000 0.00 5000 . 0. 01 0.01 50. 0.001 0 .005 0_00 5009 . 0.03 0.03 150. 0.003 0 .007 0.00 5027 . 0.04 0.04 201. 0.005 0.008 0.00 5036 . 0.05 0.05 251. 0.006 0.010 0.00 5045 . 0.07 0.07 352 . 0.008 0.011 0.00 5063 . 0.08 0.08 403 . 0.009 0. 012 0.00 5072 . 0.09 0.09 454. 0.010 0. 013 0.00 5081 . 0.10 0.10 505 . 0.012 0.�14 0.00 5090 . 0.22 0.22 1122 . 0.026 0.020 0.00 5200 . �'I 0.33 0.33 1699. 0.039 0.024 0.00 5301 . 0.45 0.45 2342 . 0.054 0.028 0.00 5412 . 0.56 0.56 2943 . 0.068 0.032 0.00 5515 . 0.67 0.67 3556. 0.082 0.035 0.00 5619 . , 0.79 0.79 4237. 0.097 0. 038 0.00 5733 . 0.90 0.90 4873 . 0.112 O.Q40 0.00 5839 . 1.01 1.01 5521. 0.127 0.043 O.QO 594E . 1.13 1.13 6242 . 0.143 0.045 0.00 6063 . 1.24 1.24 6915 . 0.159 0.047 0.00 6171 . 1.36 1.36 7663 . 0.176 0.049 0.00 629� . 1.47 1.47 8361. 0 .192 0.051 0.00 64G- . 1.58 1.58 9071. 0.208 0. 053 0.00 651: 1.70 1.70 986Q. 0.226 0. 055 0.00 663• 1.81 1.81 10595 . 0.243 0.057 0.00 674 1.92 1.92 11344 . 0.260 0.059 0.00 686 2.04 2 .04 12175. 0.279 0.060 0.00 69� 2.15 2.15 12949. 0.297 0.062 0.00 71C- 2.26 2.26 13737 . 0.315 0. 064 0.00 721 2 .38 2 .38 14611. 0.335 0.065 0.00 734� 2.49 2.49 15425. 0.354 0. 067 0.00 746 2.61 2.61 16329 . 0.375 0.068 0.00 759 4-10 R99095-1.340 Goldsmith&Associates Technical Information Report for the Plat of Maureen Hrghlands r-- 2 . 72 2 .72 �717�. 0 .394 0 . 070 0 . 00 7714 . 2 .83 2.83 18026. 0.414 0.071 0.00 7835 . 2 .95 2.95 18974. 0.436 0.073 0.00 7963 . 3 .06 3.06 19857. 0.456 0.074 0.00 809"� . 3 .17 3 .17 20754. 0.476 0. 076 0.00 8215 . 3 .29 3.29 21748. 0.499 0. 077 0.00 8351 . 3 .40 3.40 22674. 0.521 0.078 0.00 8476 . 3 .52 3.52 23699. 0. 544 0.079 0.00 8614 . 3 .63 3.63 24654. 0.566 0.081 0.00 8741 . 3 .74 3.74 25622. 0.588 0.082 0.00 887C . 3 . 86 3.86 26695. 0.613 0.083 0.00 9010 . 3 .90 3.90 27056. 0.621 0.084 0.00 9058 . 3.92 3 .92 27238. 0.625 0.085 0.00 9081 . 3 .94 3 .94 27420. 0.629 0.087 0. 00 9105_ 3 .96 3 .96 27602. 0.634 0.091 0.00 9129. 3 .98 3 .98 27785. 0.638 0.096 0.00 9152. 4 .00 4.00 27968. 0.642 0.103 �.00 9176. 4.02 4.02 28152. 0.646 0.111 0.00 9200. 4.04 4.04 28336. 0.651 0.120 0.00 9224. 4.06 4.06 28521. 0.655 0.124 0.00 9247 . 4.08 4.08 28706. 0.659 0.127 0.00 9271 . 4.19 4.19 29733. 0.683 0.140 0.00 9403 . 4.31 4.31 30870. 0.709 0.150 0.00 9548. 4.42 4.42 31928. 0.733 0.160 0. 00 9681. 4.53 4.53 33000. 0.758 0.168 0.�0 9816 . 4.60 4.60 33690. 0.773 0.173 0.00 9902 . 4.62 4.62 33888. 0.778 0.175 0.00 9926 . 4.64 4.64 34087. 0.783 0.178 0.00 9951. 4.65 4.65 34187. 0.785 0.182 0.00 9963 . 4.67 4.67 34386. 0.789 0.188 0.00 9988 . 4.69 4.69 34586. 0.794 0.195 0.00 10013 . 4.71 4.71 34787. 0.799 0.202 0.00 10038 . 4_73 4.73 34988. 0.803 0.211 0.00 10062 . 4.75 4.75 35189. 0 .808 0.214 0.00 10087 . �� 4_76 4.76 35290. 0.810 0.217 0.00 10100 . 4 .88 4.88 36511. 0 .838 0.234 0.00 10249 . 4.99 4.99 37646_ 0.864 0.249 0.00 10387 . 5.11 5.11 38902. 0.893 0.262 0.00 10539 . 5.22 5.22 40069 . 0.920 0.275 0.00 10679 . 5.33 5.33 41251. 0.947 0.286 0.00 10820 . 5.45 5.45 42559. 0.977 0.297 0.00 10974. 5.56 5.56 43774. 1. 005 0.307 0.00 11117 . 5.67 5.67 45004. 1.033 0.317 0.00 11260 . 5.79 5.79 46365. 1.064 0.327 0.00 11418 . 5 .80 5.80 46479. 1.067 0.328 0.00 11431 . 5.90 5.90 47629. 1.093 0.644 0.00 1156? . 6.00 6.00 48792. 1 .120 1.220 0.00 11690' . 6 .10 6.10 49968. 1.147 1.950 0.00 1183G . 6 .20 6.20 51158. 1.174 2.750 0.00 1196� . 6 .30 6.30 52361. 1.202 3 .040 0.00 12099 . 6 .40 6.40 53578. 1.230 3 .300 0.00 12235 . 6 .50 6.50 54808. 1.258 3 .540 0.00 12371 . 6 .60 6.60 56052. 1.287 3 .770 0.00 1250�' . 6.70 6.70 57310. 1.316 3 .980 0.00 126�: 6.80 6.80 58581. 1.345 4.180 0.00 1278= 6.90 6.90 59867. 1.374 4 .370 0.00 1292�= 7 .00 7.00 61166. 1.404 4.560 0.00 1306 7 .10 7.10 62479 . 1.434 4.730 0.00 132G' 7 .20 7.20 63807 . 1.465 4.900 0.00 1334 7.30 7 .30 65149 . 1.496 5.060 0.00 1348� . 7 .40 7 .40 66505. 1.527 5.220 0.00 13631 . 7 .50 7 .50 67875. 1 .558 5 .370 0.00 13775 . 7 .60 7 .60 69260. 1 .590 5 .520 0.00 13919. 7 .70 7 .70 70659. 1 .622 5.670 0.00 14064. 4-11 R99095-1340 Goldsmith&Associates Technical Information Report for the Plar of Maureen Highdands Hyd Inflow Outflow Peak Storage Stage E1ev (Cu-Ft) {Ac-Ft) 1 1.74 1.16 5.99 5 .99 48667. 1.117 2 0.86 0.32 5.69 5.69 45268. 1.039 3 0.87 0.28 5.27 5.27 40565. 0.931 4 1.04 0.23 4.86 4.86 36322. 0.834 5 0.92 0.22 4.78 4.78 35490. a.815 6 0.77 0.07 2 .80 2.8� 17765. 0.408 7 0.92 0.06 2.30 2 .30 14011. 0.322 8 0.71 0.08 3.34 3.34 22155. 0.509 Hyd R/D Facility Tributary Reservoir POC Outflow Outflow Inflow Inflow Target Calc 1 1.16 0.13 ******** ******* 1.21 2 0.32 0.07 ******** ******* 0.35 3 0.28 0.07 ******** 0.36 0.31 4 0.23 0.08 ******** ******* 0.25 5 0.22 0.07 ******** ******* 0.23 6 �.07 0.07 ******** ******* 0.13 7 0.06 0.08 ******** ******* 0.12 8 0.08 0.06 ******** ******* 0.12 ---------------------------------- Route Time Series through Facility Inflow Time Series File:inced.tsf Outflow Time Series File:cedoutR5 POC Time Series File:totced Inflow/Outflow Analysis Peak Inflow Discharge: 1.74 CFS at 6:00 on Jan 9 in Year 8 Peak Outflow Discharge: 1.16 CFS at 10:00 on Jan 9 in Year 8 Peak Reservoir Stage: 5.99 Ft Peak Reservoir Elev: 5.99 Ft Peak Reservoir Storage: 48667 . Cu-Ft . 1.117 Ac-Ft Add Time Series:bypced.tsf Peak Summed Discharge: 1.21 CFS at 10:00 on Jan 9 in Year 8 Point of Compliance File:totced.tsf Flow Frequency Analysis Pond Peak Discharge Rates Time Series File:cedoutr5 .;sf Project Location:Sea-Tac ---Annual Peak Flow Rates--- ----Flow Frequency Analysis------ � Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob , (CFS) (CFS) (ft) Period 0.319 2 2/09/01 20:00 1.16 5 .99 1 100. 00 0.99C 0.077 7 12/28/O1 18:00 0.319 5.69 2 25 .00 0.960 0.231 4 3/06/03 22:00 0.280 5.27 3 10.00 0.900 0.071 8 8/26/04 6:00 0.231 4.86 4 5.00 0.80C� 0.099 6 1/05/05 16:00 0.220 4.78 5 3 .00 0.6E� 0.220 5 1/18/06 23 :00 0.099 3 .99 6 2.00 0.5C�� , 0.280 3 11/24/06 7:00 0.077 3 .33 7 1.30 0.2�: I 1.16 1 1/09/08 10:00 C . 0?1 2 .?9 R 1 . 10 O , nG ' Computed Peaks 4-12 R99095-1340 Goldsmith&Associates Technical lnformation Report jor fhe Plat of Maureen Highlands Total Developed Basin Discharge Rates Time Series File:totced.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- -----rlow Frequency Analysis------- Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 0.352 2 2/09/01 18:00 1.20 1 100.00 0.990 0.116 8 1/05/02 16 :00 0.352 2 25.00 0.960 0.249 4 3/06/03 20:00 0.309 3 10.00 0 .900 0.134 6 8/26/04 2 :00 0.249 4 5.00 0 .800 0.124 7 10/28/04 17:00 0.234 5 3 .00 0 .667 0.234 5 1/18/06 22:00 0.134 6 2 .00 0.500 0.309 3 11/24/06 6:00 0.124 7 1.30 0.231 1.20 1 1/09/08 10:00 0.116 8 1.10 0.091 Computed Peaks 0.919 50.00 0.980 Flow Duration Comparison Duration Comparison Analysis Base File: exced.tsf New File: totced.tsf Cutoff Units: Discharge in CFS -----Fraction of Time----- ---------Check of Tolerance------- Cutoff Base New $Change Probability Base New �Change 0.101 0.63E-02 0.60E-02 -3. 6 0.63E-02 0.101 0 .099 -1.4 0.109 0.55E-02 0.50E-02 -8_6 0.55E-02 0.109 0.104 -4.5 0.117 0.49E-02 0.45E-02 -9.0 0.49E-02 0.117 0.110 -5.5 0.124 0.44E-02 0.40E-02 -9.3 0.44E-02 0.124 0.118 -5.5 0.132 0.38E-02 0.36E-02 -7.2 0.38E-02 0.132 0.127 -3 . 9 0.140 0.33E-02 0.32E-02 -3.4 0.33E-02 0.140 0.139 -1.1 0.148 0.30E-02 0.29E-02 -3 .3 0.30E-02 0.148 0.145 -2 .3 0.156 0.27E-02 0.25E-02 -5.5 0.27E-02 0.156 0.153 -2 .2 0.164 0.23E-02 0.22E-02 -5.0 0.23E-02 0.164 0.161 -1.9 0.172 0.19E-02 0.19E-02 0.9 0_19E-02 0.172 0.173 0.4 0.180 0.16E-02 0.16E-02 4.1 0.16E-02 0.180 0.186 3 .3 0.188 0.14E-02 0.15E-02 8.0 0_14E-02 0.188 0 .198 5.3 0.196 0.13E-02 0.15E-02 11.2 0_13E-02 0.196 0 .204 4. 3 0.204 0.11E-02 0.13E-02 14.3 0.11E-02 0.204 0.215 5. 6 0.212 O.10E-02 0.12E-02 17. 5 O.10E-02 0.212 0.221 4.4 0.220 0.93E-03 0.11E-02 17.5 0.93E-03 0.220 0.227 3 .4 0.228 0.86E-03 0.91E-03 5.7 0.86E-03 0.228 0.232 2 .0 0.236 0.73E-03 0.80E-03 8.9 0.73E-03 0.236 0.240 1.7 0.244 0.68E-03 0.70E-03 2.4 0.68E-03 0.244 0.246 0.9 0.251 0.57E-03 0.60E-03 5.7 0.57E-03 0.251 0.253 0. 8 0.259 0.49E-03 0.52E-03 6.7 0.49E-03 0.259 0.263 1.3 0.267 0.44E-03 0.44E-03 0.0 0.44E-03 0.267 0.273 2. G 0.275 0.39E-03 0.41E-03 4.2 0.39E-03 0.275 0.280 1. E 0.283 0.26E-03 0.36E-03 37 .5 0.26E-03 0.283 0.299 5. 6 0.291 0 .16E-03 0.29E-03 80.0 0.16E-03 0.291 0.311 7. 0 0.299 0.15E-03 0.26E-03 77.8 0.15E-03 0.299 0.318 6.3 0.307 0.15E-03 0.18E-03 22.2 0.15E-03 0.307 0.318 3 . 6 0.315 0.82E-04 0.15E-03 80.0 0.82E-04 0 .315 0.332 5.5 0.323 0.49E-04 0.13E-03 166.7 0.49E-04 0.323 0 .339 4. 9 0.331 0.49E-04 0.98E-04 100.0 0.49E-04 0 .331 0 .339 2 . ' 0.339 0.33E-04 0.49E-04 50.0 0_3�" Maximum positive excursion = 0.024 cfs ( 8.3 occurring at 0.294 cfs on the Base Data:excec� and at 0.318 cfs on the New Data:totced.tsf Maximum negative excursion = 0.009 cfs ( -7.1�) occurring at 0.122 cfs on the Base Data:exced.tsf and at 0.113 cfs on the New Data:totced.tsf 4-13 R9909�-1340 Goldsmi[h&Associates Technical Informatio�i�Report for�he Plat of Maureen Highlands o cedoutRS.clur :� FLOW DURATION COMPAR/SON totced.dur � exced.dur :. �... � ,�_ R �� - _� i L `�. � ...____ ��-' _"'�"_,--_0 . ,�\ � -___ ` .. � �� --__"_'_— O � \� ..-�_ �,.` �.. . DEVELOPED ��~� �_. (Pond Outf/owJ �.� r'� ' TOTAL DEVELOPED '\ �. (Pond Outflow & Bypass) ci� �;;,� � r=� U f a� �``t;`'�► N }� � O _._. --__. ___ ;.i —'. (� ��``� U �� cn 000 _ b�� Y z� �� C,�.�, I �w_ EX/STING �•,�i�,, (Forested) o'!',; ��,_; __ .^ •� o , '�` -- 00 --- O -...._ , • - _...�.. r,1_. `,'\ �.. T i..._. ' �. �. �f; :`� � � � � �7 T- --T �. i i 10-5 10-4 10�3 10-2 10-1 10° Probabilitv Exceedence F/GURE 8 Mav Creek Drainage Control Plan: The Task 4 section of this report identified a drainage problem downstream of the project site within the May Creek Basin. The problem identified is localized flooding of S.E. 124`" Street during storm events. This flooding is caused by inadequate conveyance capacity of the closed pipe portion of White Fence Ranch drainage system. Therefore, in order to prevent exacerbation of this existing problem, it is proposed that a modified KCRTS Level 2 standard be used for the May Creek detention pond. This modified standard, in addition to meeting the Level 2 flow rate and duration criteria based on the forested site condition, will control the 100 year release rate to less than the peak runoff rate under the currently cleared site conditions. The accompanying tables, printouts and graphs compare the developed discharges to the current condition and the forested (assumed existing condition). By controlling the 100 year discharge rate to less than that current (cleared) rate, exacerbation of the existing flooding problem will be prevented if not improved. Also, as shown in the flow duration curve for the May Creek detention pond, there is a significant (�20%) reduction in flow durations following development of the Preliminary Plat of Maureen Highlands when compared to the current flow durations. In addition to the flow duration curve (Figure 11), a printout of the flow duration comparison tables have also been included. By implementing the above described drainage control plan, exacerbation of the downstream flooding problem will be avoided. Additionally, implementing the KCRTS Level 2 Standard based on forested site conditions will reduce potential downstream erosion. It should be noted that the backwater conditions created by the 124�h Avenue drainage system has been accounted for in sizing of the May Creek detention pond. The King County program KCBW was used for developing the downstream tailwater curve. Pond Design Summary: Required Detention Volume = 8.89 ac.-ft. May Creek Facility Water �uality Stage-Storage Table Elevation (ft.) Area(sf) Volume(cf) Cumulative Volume(cf) 515.5 76,206 0 0 516.0 78,001 38,552 38,552 518.0 85,329 163,330 201,882 520.0 90,089 175,418 377,300 520.57 91,282 51,691 428.991 Designed Water Quality Volume = 8.61 ac.ft. - EI. 510.0 ft. to 515.5 ft. Designed Detention Volume = 9.84 ac.-ft. l�:tiJ`.�l-l.i�.;1�U1�Slluili �i .ia_��I.1iC� [c�i�iii�ci� i�,r�il��eh�!h 'e�7i,l1 jiN in� /�«u ;:llu<<lce�� lli:;ii4:riil.� Pond Surface Data Pond Bottom = 509.0 W.Q. W.S. = 515.50 100 yr. W.S. = 520.57 Berm Elev. = 522.00 Orifice Sizing Table: � Orifice Diameter Elevation 1 3.00 513.50 ft. 2 5.00 518.25 ft. 3 3.50 518.80 ft. Pond Outlet Elevation = 515.50 ft. Baffle Wall = 520.40 ft. The following KCRTS pond document file gives the total pond plus bypass area peak discharge rates (summarized below) compared to existing (forested) and the current (cleared) conditions. Also included in the pond document file is the flow duration comparison for establishing compliance with the proposed m�dified KCRTS Level 2 flow control standard. Flow Rate (cfs) Event Existing (forested) Current (cleared) Developed 2-year 0.94 1.21 0.61 10-year 1.64 2.23 1.62 100-Vear 2 82 4.1 3 68 The accompanying tables, printouts and graphs compare the developed discharges to the current condition and the forested condition assumed for design of the KCRTS Level 2 pond. 4-16 R9909�-1340 Goldsmith & Associates Tecluaicul hifornrnrion ReporlJnr dre Pla1 of Maureen Highlands - � � PORTION OF THE E. I/2 OF SEC. II TWP. 23, R 5 E.. W.M. I i I I � HOTE: SEE SHT.5-25A FOR POND � I J b _�- OUTFALL DETAILS AND �___ �-1�- - LEGEND: ' GABION WALL SECTIONS. - a � � � � ----_-_ -_ _--_--_-_-_--_--_-_-------------- --------------_-_ -- --- -_ _ � - � ■ TYPE I CATCH BASIN W -- -----------� �-------------- - - --- - - - - - - - - '--------- � W II . -- - ----- � ---------------------------------------�--a-�----_____ ROUND SOLID COVER (TYP) WITH LOCKING BOLTS SEE C.O.R. DWG NAME BR29 RIM EL=523.0 SEE SHT 8-14 0 OVERFLOW NOTCH WEIR � (VERTICAL BAR GRATE) � 100 YR W.S. AND � 8 � TOP BAFFLE WALL = 520.40 I.E. = 520.60 ORIFICE N0. 3, INV = 518.80 ELBOW (TYP) = ORIFICE D�A.=3.5" PER C.O.R. DWG NAME BR04 _ _ ORIFICE PLATE WELDED TO SEE SHT 5-31 6�� CMP ELBOW I — J - ORIFICE N0. 2, INV. = 518.25 ORIFICE DIA.=5.0" 84" CB TYPE II ° ORIFICE PLATE WELDED TO 6" CMP ELBOW �g" pIPE (INVERTED) � � 8 LF 18'� SD OUT TO DETENTION POND �; --� e ( e 0.68 � — -- f� — — — INV.EL=515.50 � c INV.EL=515.50 ' CLEANOUT GATE: SHEAR GATE — WITH CONTROL ROD. _ ORIFICE N0. I, EL=513.50 PER C.O.R DWG NAME BR05 ORIFICE DIA.=3.0" I SEE SHT 5-31 " FRAME 8� LADDER OR STEPS SEE C.O.R. SP PG. 6035 ` SEE SHT 5-29 � BOTTOM=511.50 _ ` ,J ORIFICE PLATE `' SEE C.O.R DWG NAME BR06 P R 0 F I L E MAY CREEK POND OUTLET BAFFLE WALL CONTROL STRUCTURE, TYPE II - 84" SCALE: 1��=2� (PER C.O.R. STD DRAWING BR06) FIGURE 10 May Creek Pond Retention/Detention Facilit}� Type of FaCility: Detention Pond Side Slope: 3.00 H:iV Pond Bottom Length: 367.74 ft Pond Bottom Width: 183.87 ft Pond Bottom Area: 67618. sq. ft Top Area at 1 ft. FB: 88398. sq. ft 2.029 acres Effective Storage Depth: 4.90 ft Stage 0 Elevation: 515.50 ft Storage Volume: 372473. cu. ft 8.551 ac-ft Riser Head: 4.90 ft Riser Diameter: 26.74 inches Number of orifices: 3 Full Head Pipe Orifice # Height Diameter Discharge Diameter (ft) (in) (CFS) (in) 1 0.00 3.00 0.540 2 2.75 5.00 0.994 S.0 3 3.3Q 3.50 0.420 6.0 Top Notch Weir: None Outflow Rating Curve: 124th.bwt Stage Elevation Storage Discharge Percolation Surf Area (ft) (ft) (cu. ft) (ac-ft) (cfs) (cfs) (sq. ft) 0.00 515.50 0. 0.000 0.000 0.00 67618. 0.03 515.53 2030. 0.047 0.043 0.00 67717. 0.06 515.56 4063. 0.093 0.061 0.00 67817. 0.09 515.59 6099. 0.140 0.075 0_00 67916. 0.13 515.63 8818. 0.202 0.086 0.40 68049. 0.16 515.66 10861. 0.249 0.096 0.00 68148. 0.19 515.69 12907. 0.296 0.106 0.00 68248. 0.22 515.72 14956. 0.343 0.114 0.00 68348. 0.25 515.75 17008. 0.390 0.122 0.00 68448. 0.35 515.85 23870. 0_548 0.144 0.00 68781. 0.45 515.95 30764. 0.706 0.164 0.00 69115. 0.55 516.05 37692_ 0.865 0.181 0.00 69449. 0.65 516.15 44654. 1.025 0.197 O.QO 69785. 0.75 516.25 51649. 1.186 0.211 0.40 70121_ 0.85 516.35 58678. 1.347 0.225 0.00 70457. 0.95 516.45 65741. 1.509 0.238 0.00 70795. 1.05 516.55 72837. 1.672 0.250 0.00 71133. 1.15 516.65 79967. 1.836 0.262 0.00 71472. 1.25 516.75 87132. 2.000 0.273 0.00 71811. 1.35 516.85 94330. 2.166 0.284 0.00 72152. 1.45 516.95 101562. 2.332 0.294 0.00 72493. 1.55 517.05 108828. 2.498 0.304 0.00 72835. 1.65 517.15 116129. 2.666 0.314 0.00 73177. 1.75 517.25 123464. 2.834 0.323 0.00 7352G. 1.85 517.35 130833. 3.004 0.332 0.00 73864. 1.95 517.45 138237. 3.173 0.341 0.00 74209. 2.05 517.55 145675. 3.344 0.350 0.00 74554. 2.15 517.65 153148. 3.516 0.358 0.00 7490� . 2.25 517.75 160655. 3.688 0.365 0.00 7524" . 2.35 517.85 168197. 3.861 0.372 0.00 7559� 2.45 517.95 175774. 4.035 0.379 0.00 7594� 2.55 518.05 183386. 4.210 0.385 0.00 7629� 2.65 518.15 191032. 4.385 0.392 0.00 7664= 2.75 518.25 198714. 4.562 0.398 0.00 7699. 2.80 518_30 202568. 4.650 0.407 0.00 771E 2.85 518.35 206431. 4.739 0.429 0.00 773� 2.91 518.41 211078. 4.846 a.463 0.00 775_ 2.96 518.46 214960. 4.935 0.508 0.00 777: 3.01 518.51 218851. 5.024 0.571 0.00 779�: 3.06 518.56 222750. 5.114 0.645 0.00 7808�. 3.11 518.61 226659. 5.203 0.809 0.00 78259. 4-19 R99095-1.340 Goldsmith& Associates Technical Information Reporr for rhe Plat of Maureen Highlands 3.17 518.67 231361. 5.311 0.640 O.OQ 78472. 3.22 518.72 235289. 5.401 0.87� 0.00 78648. 3.30 518.80 241592. 5_546 0.914 0.00 78932. 3.34 518.84 244752. 5.619 0.936 0.00 79074. 3.37 518.87 247126. 5.673 0.963 0.00 79181. 3.41 518.91 250296. 5.746 0.996 0.00 79323. 3.45 518.95 253472. 5.819 1.030 0.00 79465. 3.48 518.98 255857. 5.874 1.080 0.00 79572. 3.52 519.02 259043. 5.947 1.120 0.00 79714. 3.56 519.06 262234. 6_020 1.200 0.00 79857. 3.59 519.09 264632. 6.075 1.230 0.00 79964. 3.63 519.13 267833. 6.149 1.260 0.00 80107. 3_73 519.23 275862. 6.333 1.330 0.00 80464. 3.83 519.33 283926. 6.518 1.390 0.00 80822. 3.93 519.43 292026. 6.704 1.450 0.00 81181. 4.03 519.53 300162. 6.891 1.510 0.00 81541. 4.13 519.63 308334. 7.078 1.560 0.00 81901. 4.23 519.73 316542. 7.267 1.610 0.00 82262. 4.33 519.83 324787. 7.456 1.660 0.00 82624. 4.43 519.93 333067. 7.646 1.710 0.00 82986. 4.53 520.03 341384. 7.837 1.760 0.00 83350. 4.63 520.13 349737. 8.029 1.800 0.00 83714. 4.73 520.23 358127. 8.221 1.850 0.00 84078. 4.83 520.33 366553. 8.415 1.890 0.00 84444. 4.90 520.40 372473. 8.551 1.920 0_00 84700. 5.00 520.50 38�961. 8.746 2.640 0.00 85066. 5.10 520.60 389486. 8.941 3.920 0.00 85434. 5.20 520.70 398048. 9.138 5.550 0.00 85802. 5.30 520.80 406647. 9.335 7.510 0.00 86171. 5.40 520.90 415282. 9.534 9.730 0.00 86540. 5.50 521.00 423955. 9.733 12.180 0.00 86910. 5.60 521.10 432664. 9.933 14.840 0.00 87281. 5.70 521.20 441411. 10.133 17.700 0.00 87653. 5.80 521.30 450195. 10.335 20.020 0.00 88025. 5.90 521.40 459016. 10.538 21.020 0.00 88398. 6.00 521.50 467875. 10.741 21.970 0.00 88772. 6.10 521.60 476771. 10.945 22.880 0.00 89147. 6_20 521.70 485704. 11.150 23.750 0.00 89522. 6.30 521.80 494675. 11.356 24.60� 0.00 89898. 6.40 521.90 503684. 11.563 25.410 0.00 90275. 6.50 522.00 512730. 11.771 26.200 0.00 90652. 6.60 522.10 521814. 11.979 26.960 0.00 91030. 6.70 522.20 530936. 12.189 27.70� 0.00 91409. 6.80 522.30 540096. 12.399 28.420 0.00 91789. 6.90 522.40 549294. 12.610 29.130 0.00 92169. Hyd Inflow Outflow Peak Storage Stage Elev (Cu-Ft) (Ac-Ft) 1 11.28 3.59 5.07 520.57 387282. 8.891 2 5.62 1.81 4.65 520.15 351685. 8.074 3 5.62 1.54 4.10 519.60 305673. 7.017 4 6.73 1.51 4.03 519.53 299986. 6.887 5 5.93 1.05 3.46 518.96 254434. 5.841 6 3.52 0.59 3.02 518.52 219884. 5.048 7 4.52 0.41 2.80 518.30 202684. 4.653 i 8 4.84 0.34 1.93 517.43 136398. 3.131 Hyd R/D Facility Tributary Reservoir POC Outflow I Outflow Inflow Inflow Target Calc 1 3.59 0.30 ******** 4.10 3.68 I 2 1.81 0.13 ******** ******* 1.91 3 1.54 0.12 ******** ******* 1.62 4 1.51 0.16 ******** ******* 1.58 5 1.05 0.13 ******** ******* 1.13 6 0.59 0.07 ******** ******* 0.61 7 0.41 0.06 ******** ******* 0.43 8 0.34 0.03 **x***** ******* 0.35 4-20 R99095-1340 Goldsmith&Associates Technical Information Report for the Plat of Muureen Highlands ---------------------------------- Route Time Series through Facility Inflow Time Series File:maydev3.tsf Outflow Time Series File:mayout5 POC Time Series File:maytot Inflow/Outflow Analysis Peak Inflow Discharge: 11.30 CFS at 6:00 on Jan 9 in Year 8 Peak Outflow Discharge: 3_59 CFS at 11:00 on Jan 9 in Year S Peak Reservoir Stage: 5.07 Ft Peak Reservoir Elev: 520.57 Ft Peak Reservoir Storage: 387282. Cu-Ft . 8.891 Ac-Ft Add Time Series:maybyp.tsf Peak Summed Discharge: 3.68 CFS at 11:00 on Jan 9 in Year 8 Point of Compliance File:maytot.tsf Flow Frequency Analysis Pond Peak Discharge Time Series File:mayout5.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- -----Flow Frequency Analysis------- Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) (ft) Period 1.84 2 2/09/O1 20:00 3.59 5.07 1 100_00 0.990 0.424 7 1/07/02 4:00 1.84 4.72 2 25.00 a.960 1.51 4 3/06/03 22:00 1.54 4.a9 3 10.00 0.900 0.339 8 8/26/04 7:00 1.51 4.03 4 5.00 0.800 0.591 6 1/OS/05 3:00 1.05 3.46 5 3 .00 0.667 1.05 5 1/19/06 0:00 0.591 3.02 6 2.00 0.500 1.54 3 11/24/06 8:0� 0.424 2.84 7 1.30 0.231 3.59 1 1/09/08 11:00 0.339 1.92 8 1.10 0.a91 Computed Peaks 3.01 5.03 50.00 0.980 Flow Frequency Analysis Total - (Pond + Bypass) Peak Discharges �I Time Series File:maytot.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- -----Flow Frequency Analysis------- � Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob I (CFS) (CFS) Period I 1.94 2 2/09/O1 20:00 3.67 1 100.00 0.990 I 0.447 7 1/a7/02 4:00 1.94 2 25.00 0.960 i 1.57 4 3/06/03 21:00 1.62 3 10.0� 0.900 � 0.352 8 8/26/04 7:00 1.57 4 5.0� 0.800 0.611 6 1/08/05 3:00 1.13 5 3.00 0.667 ' 1.13 5 1/19/06 0:00 0.611 6 2.00 0.500 1.62 3 11/24/06 7:00 0.447 7 1.30 0.231 �, 3.67 1 1/09/08 11:00 0.352 8 1.10 0.091 I Computed Peaks 3.1� 50.00 0.980 �I i Flow Duration from Time Series File:mayout5.tsf i Cutoff Count Frequency CDF Exceedence_Probability CFS $ � $ 0.026 31698 51_693 51.693 48.307 0.483E+00 0.078 5783 9.431 61.124 38.876 0.389E+00 0.129 6114 9.971 71.094 28.906 0.289E+00 0.181 5175 8.439 79.534 20.466 0.205E+00 0.233 4507 7.350 86.884 13.116 0.131E+00 0.284 33a6 5_391 92.275 7.725 0.773E-01 0.336 1824 2.975 95.250 4.750 0.475E-01 0.388 1736 2.831 98.081 1.919 0.192E-01 4-21 R99095-1340 Goldsmith&Associates Technical Information Report for the Plar of Maureen Highlands 0.439 587 0.957 99.038 0.962 0.962E-02 0.491 142 0.232 99.269 0.731 0.731E-02 0.542 78 0.127 99.397 0.603 0.603E-02 0.594 41 0.067 99.463 0.537 0.537E-02 0.646 30 0.049 99.512 0.488 0.488E-02 0.697 15 0.024 99.537 0.463 0.463E-02 0.749 11 0.018 99.555 0.445 0.445E-02 0.801 10 0.016 99.571 0.429 0.429E-02 0.652 43 0.070 99.641 0.359 0.359E-02 0.904 35 0.057 99.698 0.302 0.302E-02 0.956 24 0.039 99.737 0.263 0.263E-02 1.01 14 0.023 99.760 0.240 0.240E-02 1.06 22 0.036 99.796 0.204 0.204E-02 1.11 11 0.018 99.814 0.186 0.186E-02 1.16 9 0.015 99.829 0.171 0.171E-02 1.21 9 0.015 99.843 0.157 0_157E-02 1.27 10 0.016 99.860 0.140 0.140E-02 1.32 7 0.011 99.871 0.129 0.129E-02 1.37 10 0.016 99.887 0.113 0.113E-02 1.42 9 0.015 99.902 0.098 0.978E-03 1.47 10 0.016 99.918 0.082 0.815E-03 1.52 12 0.020 99.938 0.062 0.620E-03 1.58 14 0.023 99.961 0.039 0.391E-03 1.63 6 0.010 99.971 0.029 0.294E-03 1.68 3 0.005 99.976 0.024 0.245E-03 1.73 4 0_007 99.982 0.018 0.179E-03 1.78 3 0.005 99.987 0.013 0.130E-03 1.83 6 0.010 99.997 0_003 0.326E-04 Flow Duration from Time Series File:maytot.tsf Cutoff Count Frequency CDF Exceedence_Probability CFS $ $ $ 0.028 31910 52.038 52.038 47_962 0.480E+00 0.082 6075 9.907 61_946 38.054 0.381E+00 0.136 6305 10.282 72.228 27.772 0.278E+00 0.191 5016 8.180 80.408 19.592 0_196E+00 0.245 4639 7.565 87.973 12.027 0.120E+00 0.299 2892 4.716 92.689 7.311 0.731E-01 0.354 1880 3.066 95.755 4.245 0.424E-01 0.408 1500 2.446 98.201 1.799 0.180E-01 � 0.462 516 0.841 99.043 0.957 0.957E-02 0.517 140 0.228 99.271 0.729 0.729E-02 0.571 81 0.132 99.403 0.597 0.597E-02 � 0.625 38 0.a62 99.465 0.535 0.535E-02 0.680 32 0.a52 99.517 0.483 0.483E-02 0.734 17 0.028 99.545 0.455 0.455E-02 0.788 7 0.011 99.556 0.444 0.444E-02 0.843 18 0.029 99.586 0.414 0.414E-02 0.897 43 0.070 99.656 0.344 0.344E-02 0.951 29 0.047 99.703 0.297 0_297E-02 1.01 20 0.033 99.736 0.264 0.264E-02 1.06 16 0.026 99.762 0.238 0.238E-02 1.11 21 0.034 99.796 0.204 0.204E-02 1.17 12 0.020 99.816 0.184 0.184E-02 1.22 S 0.013 99.829 0.171 0.171E-02 1.28 8 0.013 99.642 0.158 0.158E-02 1.33 13 0.021 99.863 0.137 0.137E-02 1.39 7 0.011 99.874 0.126 0.126E-02 1.44 9 0.015 99.889 0.111 0.111E-02 � 1.49 10 0.016 99.905 0.095 0.946E-03 I 1.55 12 0.020 99.925 0.075 0.750E-03 1.60 12 �.020 99.945 0.055 0.554E-03 1.66 13 0.021 99.966 0.034 0.342E-03 1.71 3 0.005 99.971 0.029 0.294E-03 � 1.77 3 0.405 99.976 0.024 0.245E-03 1.82 4 0.007 99.982 0_018 0.179E-03 1.87 4 0.007 99.989 0.011 0.114E-03 1.93 5 0.008 99.997 0.003 0.326E-04 4-22 ��, R99095-1340 Goldsmith&Associates Technica!Jnformarion Report for the Plat of Maureen Highlands �' Pond Peak Discharge Rates Flow Frequency Analysis Time Series File:mayout5.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- -----Flow Frequency Analysis------- Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) (ft) Period 1.84 2 2/09/01 20:00 3.59 5.07 1 100.00 0.990 0.424 7 1/07/02 4:00 1.84 4.72 2 25.00 0.960 1.51 4 3/06/03 22:00 1.54 4.09 3 10.00 0.900 0.339 8 8/26/04 7:00 1.51 4.03 4 5.00 0.800 0.591 6 1/OS/05 3:00 1.05 3.46 5 3.00 0.667 1.05 5 1/19/06 0:00 0.591 3.02 6 2.00 0.500 1.54 3 11/24/06 8:Q0 0.424 2.84 7 1.30 0.231 3.59 1 1/09/08 11:0� 0.339 1.92 8 1.10 0_091 Computed Peaks 3.01 5.03 50.00 0.980 4-23 R99095-1.340 Goldsmith &Associates fechnical Lifornaarion Report.for the Plat nf,4�aureen High(ands Flow Duration Comparison - Pond Discharges Compared to Existing (Forested) Duration Comparison Anaylsis Base File: mayex2 .tsf New File: maytot.tsf Cutoff Units: Discharge in CFS -----Fraction of Time----- ---------Check of Tolerance------- 'i Cutoff Base New $Change Probability Base New �Change 0.469 0.95E-02 0.92E-02 -2. 8 0.95E-02 0.469 0.466 -0.6 0.524 0.77E-02 0.69E-02 -10.3 0.77E-02 0.524 0.505 -3 .6 0.579 0.66E-02 0.59E-02 -10.6 0.66E-02 0.579 0.534 -7.9 0.634 0.58E-02 0.52E-02 -10.4 0.58E-02 0.634 0.586 -7.6 0.690 0.52E-02 0.48E-02 -8 .4 0.52E-02 0.690 0.634 -8.1 0.745 0.48E-02 0.45E-02 -5.1 0.48E-02 0.745 0.703 -5 .6 0.800 0.42E-02 0.44E-02 4.3 0.42E-02 0.800 0.839 4 .9 0.855 0.37E-02 0.40E-02 8.3 0.37E-02 0.855 0.876 2 .4 0.910 0.33E-02 0.34E-02 2 .5 0.33E-02 0.910 0.921 1.1 0.965 0.30E-02 0.28E-02 -4.4 0.30E-02 0.965 0.953 -1.3 1.02 0.27E-02 0.26E-02 -4.8 0.27E-02 1.02 0.996 -2.4 1.08 0.23E-02 0.22E-02 -5.6 0.23E-02 1.08 1.06 -1_1 1.13 0.21E-02 0.20E-02 -4.7 0.21E-02 1.13 1.11 -1.5 1.19 0.17E-02 0.18E-02 1.9 0.17E-02 1.19 1.20 1.2 1.24 0.15E-02 0.17E-02 12 .0 0.15E-02 1.24 1.30 4.4 1.30 0.13E-02 0.15E-02 17.9 0.13E-02 1.30 1.38 6.1 1.35 0.11E-02 0.13E-02 21.2 0.11E-02 1.35 1.45 7.1 1.41 0.90E-03 0.12E-02 34.5 0.90E-03 1.41 1.51 7.4 1.46 0.72E-03 O.10E-02 43.2 0.72E-03 1 .46 1.57 7. 5 1.52 0.59E-03 0. 86E-03 47.2 0.59E-03 1.52 1.60 5.2 1.57 0.51E-03 0.72E-03 41.9 0.51E-03 1.57 1.61 2 . 6 1.63 0.39E-03 0.44E-03 12 .5 0.39E-03 1.63 1. 64 1. 1 1.68 0.28E-03 0.33E-03 17 .6 0.28E-03 1.68 1.73 2 .7 1.74 0.26E-03 0.26E-03 0.0 0.26E-03 1.74 1.76 1 .2 1.79 0.20E-03 0.21E-03 8.3 0.20E-03 1.79 1 .82 1.3 1.85 0.16E-03 0.16E-03 0.0 0.16E-03 1.85 1.85 0.0 1.90 0.15E-03 0.65E-04 -55.6 0.15E-03 1.90 1.85 -2 . 5 1.96 0.13E-03 O.00E+00 -100.0 0.13E-03 1.96 1.87 -4 .6 2. 01 0.11E-03 O.00E+00 -100.0 0.11E-03 2 . 01 1.88 -6.7 2.07 0.82E-04 O.00E+00 -100.0 0. 82E-04 2 .07 1.90 -8.2 2.12 0.49E-04 O.00E+00 -100.0 0.49E-04 2 .12 1.92 -9 .4 2.18 0.16E-04 O.00E+00 -100.0 0.16E-04 2 .18 1.94 -11 .1 Maximum positive excursion = 0.117 cfs ( 8.2�) occurring at 1.42 cfs on the Base Data:mayex2 . tsf and at 1.54 cfs on the New Data:maytot.tsf Maximum negative excursion = 0.245 cfs (-11.2%j occurring at 2.18 cfs on the Base Data:mayex2 .tsf and at 1.94 cfs on the New Data:maytot.tsf 4-24 R99095-1.340 Goldsmith & Associates Terhnicu(biformation Report for the Plat of M�ureen Higl:(ands FLOW DURATION COMPAR/SON mayex2.dur .> maytot.dur ♦ maycu2.dur c:; � N ---- ..._�1....,,. ��.. ---___._ � __..�� ;. � . ...--- �c ---.�._.. . . . . i N ...__. _--- Q '---------_____ �� DEVELOPED --._ . '.;_, �:�_ - � CURRENT �'•� , -- �'� � \ ; (C/earedJ cn � � -�� _ _ �. — - -- U y� "�� ,, °' EX/STNVG � �'�� `u (Forested) �,�`� U �,� � N '— -------- � � __ _ �'. � � ,,��'. � .� � . . �.. .._. . ----- -` .._— -------.. _. _..—. .._.__.__._ .__�_ _ O �Q ��z y�� ,� .,. ., � v.____: _..�_�_ _ _ - --- -------- o _ ___, ._ - ._._._. .. .. o •. ��. �� 10-5 1p'4 �p-3 ip-2 ip-� 100 Probability Exceedence FIGURE 11 Current (Cleared) Conditions Peak Runoff Rates Flow Frequency Analysis, Time Series File:maycur2 .tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- -----Flow Frequency Analysis------- Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 2.44 2 2/09/O1 18:00 4.10 1 100.00 0.990 0.894 7 1/05/02 16:00 2 .44 2 25.00 0.960 2 .23 3 2/28/03 3 :00 2 .23 3 10.00 0.900 0.235 8 3/24/04 19:00 2.02 4 5.00 0.800 1.21 6 1/05/05 8:00 1.95 5 3.00 0.667 2.02 4 1/18/06 16:00 1.21 6 2.00 0.500 1.95 5 11/24/06 4:00 0.894 7 1.30 0.231 4.10 1 1/09/08 6:00 0.235 8 1.10 0.091 Computed Peaks 3 .55 50.00 0.980 Flow Duration Comparison - Pond Discharges Compared to Current (Cleared) Duration Comparison Anaylsis Base File: maycur2.tsf New File: maytot.tsf Cutoff Units: Discharge in CFS -----Fraction of Time----- ---------Check of Tolerance------- Cutoff Base New �Change Probability Base New �Change 0.468 0.16E-01 0.92E-02 -42. 5 0.16E-01 0.468 0.412 -12 .0 0.531 0.12E-01 0.66E-02 -45.6 0.12E-01 0.531 0.435 -18.2 0.595 0.95E-02 0.57E-02 -40.0 0.95E-02 0.595 0.465 -21. 8 0.658 0 .77E-02 0.50E-02 -34.3 0.77E-02 0. 658 0.507 -23 . 1 ' 0.722 0.66E-02 0.46E-02 -29.7 0.66E-02 0.722 0.533 -26 .2 0.785 0.58E-02 0.45E-02 -23.5 0.58E-02 0.785 0.587 -25. 3 0.849 0.52E-02 0.41E-02 -20.8 0.52E-02 0.849 0.640 -24. 6 0.912 0.46E-02 0.34E-02 -27.7 0.46E-02 0.912 0.717 -21.4 0.976 0.40E-02 0.28E-02 -29. 8 0.40E-02 0.976 0.858 -12.1 1.04 0.35E-02 0.25E-02 -30.0 0.35E-02 1.04 0.890 -14.3 1.10 0.31E-02 0.21E-02 -31.9 0.31E-02 1.10 0.944 -14.4 1.17 0 .28E-02 0.18E-02 -33 .5 0.28E-02 1.17 0.978 -16.2 1.23 0.24E-02 0.17E-02 -30.7 0.24E-02 1.23 1.05 -14. 8 1.29 0.22E-02 0.15E-02 -30.3 0.22E-02 1.29 1.09 -15.6 1.36 0.18E-02 0.13E-02 -29.2 0.18E-02 1.36 1.17 -13 _7 1.42 0.15E-02 0.12E-02 -24.2 0.15E-02 1.42 1.28 -9. � 1.48 0.13E-02 0.98E-03 -26. 8 0.13E-02 1.48 1.35 -9 . 1 1.55 0.11E-02 0.80E-03 -27.9 0.11E-02 1.55 1.44 -6.7 1.61 0.96E-03 0.55E-03 -42.4 0.96E-03 1 .61 1.49 -7 . E 1.67 0.85E-03 0.33E-03 -61.5 0.85E-03 1.67 1.53 -8.7 1.74 0.72E-03 0.26E-03 -63 .6 0.72E-03 1.74 1.57 -9. 6 1 .80 0.57E-03 0.21E-03 -62 .9 0.57E-03 1.80 1.60 -11.2 1.86 0.47E-03 0.13E-03 -72.4 0.47E-03 1 .86 1.62 -13 .1 1.93 0.34E-03 0.33E-04 -90.5 0.34E-03 1.93 1.65 -14.2 1.99 0.24E-03 O.00E+00 -100.0 0.24E-03 1.99 1.77 -11.0 2.05 0.18E-03 O.00E+00 -100.0 0.18E-03 2 .05 1. 82 -11.4 2 .12 0.16E-03 O.00E+00 -100.0 0.16E-03 2 .12 1.85 -12 .7 2.18 0.13E-03 O.00E+00 -100.0 0.13E-03 2 .18 1.87 -14.4 2.24 0.98E-04 O.00E+00 -100. 0 0.98E-04 2 .24 1.89 -15.7 2 .31 0.65E-04 O.00E+00 -100.0 0.65E-04 2 .31 1.91 -17.2 2.37 0.33E-04 O.00E+00 -100.0 0.33E-04 2 .37 1.93 -18 .6 2.44 0.16E-04 O.00E+00 -100.0 0.16E-04 2 .44 1 .94 -20 .5 There is no positive excursion Maximum negative excursion = 0.196 cfs (-26.5�) occurring at 0.742 cfs on the Base Data:maycur2 .tsf and at 0.545 cfs on the New Data:maytot.tsf 4-26 R9909�-1.340 Goldsmi[h& Associates Technicnl Injarmutron Repart(or d7e Plut q(�1�Iaureen Highlands SE 124t'' Street Open Ditch KCBW Model BACKWATER COMPUTER PROGRAM FOR OPEN CHANNELS Channel Data Filename:124th.bwc Tailwater from HW/TW File:124thpipe.bwt Discharge Range:0.5 to 5. Step of 0.5 [cfs] STATION 0.04: INVERT= 514.53 FT EC=1.15 Q-RATI0=0.00 CROSS-SECTION DATA: DIST/STAGE IS MEASURED FROM INVERT; N-FAC IS MEASURED BETWEEN STAGES LEFT(FT) STAGE(FT) N-FACTOR * RIGHT(FT) STAGE(FT) N-FACTOR 2.00 1.00 0.030 * 1.50 1.00 0.030 20.00 3.00 0.050 * 3.50 3.00 0.050 Q(CrS) Y1(FT) WS ELEV. * YC-IN YN-IN Q-TW TW-HT N-Y1 A-Y1 WP-Y1 V-Y1 .Ir*x*fr:k�tf�k'IrirfrYrfrir�t�t*it*�thrt�rit�trt:Fi.�tikir#itir�rxit�t�tit�cirlrf�tir�tirYrit4lrir�t�t�titir.t4trvtiritirlritzlr+tf�t�kf f irR 0.50 0.81 515.34 * 0.36 0_39 0.50 0.81 0.030 1.15 3.27 0.44 1.00 0.92 515.45 * 0.4B 0.51 1.00 0.92 0.030 1.48 3.72 0.68 1.50 1.08 515.61 * 0.56 0.59 1.50 1.08 0.034 2.06 4.88 0.73 2.00 1.22 515.75 * 0.63 0.66 2.00 1.22 0.038 2.76 6.34 0.72 2.50 1.38 515.91 * 0.64 0.72 2.50 1.38 0.041 3.80 8.02 0.66 3.00 1.56 516.09 * 0.74 0.77 3.00 1.56 0.042 5.28 9.90 0.57 3.50 1.77 516.30 * 0.78 0.81 3.50 1.77 0.044 7.41 12.10 0.47 4.00 2.00 516.53 * 0.83 0.86 4.00 2.00 0.045 10.25 14.51 0.39 4.50 2.25 516.78 * 0.87 0.89 4.50 2.25 0.046 13 .94 17.13 0.32 5.00 2.58 517.11 * 0.90 0.93 5.00 2.58 0.046 19.76 20.58 0.25 ****REACH NO. 1: L�NGTH= 37.Q0 FT AVG.GRADE= 1.54� **** STATION 37.00: INVERT= 515.10 FT EC=1.15 Q-RATI0=0.00 CROSS-SECTION DATA: DIST/STAGE IS MEASURED FROM INVERT; N-FAC IS MEASURED BETWEEN STAGES LEFT(FT) STAGE(FT) N-FACTOR * RIGHT(FT) STAGE(FT) N-FACTOR 2.00 0.90 0.030 * 1.50 0.90 0.030 6.00 2.90 0.050 * 3.00 2.90 0.050 Q(CFS) Y1(FT) WS ELEV. * YC-IN YN-IN YC-OT YN-OT N-Y1 A-Y1 WP-Y1 V-Y1 +.*.,c**x**,r+*****,r**.*.***,r****,r�.**,r**�,r**********k****+k�+:,r*****.**,.****.*,r,r � 0.50 0.40 515.50 * 0.35 0.00 0.35 0.38 0.030 0.31 1.75 1.61 � 1.00 0.52 515.62 * 0.46 0.00 0.46 0.49 0.030 0.53 2.28 1.90 1.50 0.63 515.73 * 0.54 0.00 0.54 0.57 0.030 0.77 2.76 1.94 2.00 0.74 515.84 * 0.60 0.00 0.60 0.63 0.030 1.06 3.24 1.88 � 2.50 0.87 515.97 * 0.66 0.00 0.66 0.69 0.030 1.47 3.81 1.70 � 3.00 1.03 516.13 * 0.71 0.00 0.71 0.73 0.032 2.05 4.40 1.46 3.50 1.22 516.32 * 0.75 0.00 0.75 0.78 0.035 2.84 5.06 1.23 4.00 1.44 516.54 * 0.79 0.00 0.79 0.82 0.037 3.87 5.82 1.03 4.50 1.69 516.79 * 0.83 0.0a 0.83 0.85 0.439 5.20 6.70 0.87 5.00 2.02 517.12 * 0.87 0.00 0.87 0.89 0.041 7.22 7.85 0.69 '"'*REACH NO. 2: LENGTH= 57.00 FT AVG.GRADE= -0.88$ '�*** STATION 94.00: INVERT= 514.60 FT EC=1.15 Q-RATI0=0.00 II CROSS-SECTION DATA: DIST/STAGE IS MEASURED FROM INVERT; N-FAC IS MEASURED BETWEEN STAGES i LEFT(FT) STAGE(FT) N-FACTOR * RIGHT(FT) STAGE(FT) N-FACTOR 2.00 1.40 0.030 * 2.50 1.40 0.030 5.00 3.40 0.a50 * 6.50 3.40 0.050 Q(CFS) Y1(FT) WS ELEV. * YC-IN YN-IN YC-OT YN-OT N-Y1 A-Y1 WP-Y1 V-Y1 I +****�k******rt**********�k************�k*Yrf*****1r*******�k*****k*�t***�t*YrRYr********* � 0.50 1.25 515.85 * 0.37 0.00 0.37 0.00 0.030 2.51 4.74 0.20 1.00 1.39 5=5.49 * Q.49 O.QO 0.49 0.00 0.030 3 .11 5.27 Q.32 4-27 R9909�-1340 Goldsmith&Associates Technicul Informatior�Report fiir the Plaf ojMaureen Highlands II 1.50 1.44 516.04 * 0.58 0.00 0.58 0.00 0.031 3.33 5.47 0.45 2.00 1_49 516.09 * 0.65 0.00 0.65 0.00 0.031 3.57 5.67 0.56 2.50 1.55 516.15 * 0.71 0.00 0.71 0.00 0.032 3.86 5.91 0.65 3.00 1.65 516.25 * 0.76 0.00 0.76 0.00 0.034 4.38 6.32 0.68 3.50 1.81 516.41 * 0.81 0.00 0.81 0.00 0.035 5.29 6.96 0_66 4.00 2.00 516.60 * 0.85 0.00 0.85 0.00 0.037 6.48 7.73 0.62 4.50 2.23 516.83 * 0.90 0.00 0.90 0.00 0.038 8.09 8.66 0.56 5.00 2.55 517.15 * 0.93 0.00 0.93 0.00 0.040 10.64 9.95 0.47 ROUTING DATA RESULTS: STAGE(FT) DISCHARGE(CFS) STORAGE(CU-FT) PERM-AREA(SQ-FT) 0.00 0.00 0.0 0.0 ' 0.81 0.50 96.0 277.9 0.92 1.00 129.2 326.0 1.08 1.50 158.0 375.8 1.22 2.00 191.4 431.3 1.38 2.50 238.2 495.9 1.56 3.00 307.6 569.8 1.77 3.50 409.6 660.0 2.00 4.00 544.6 762.5 2.25 4.50 721.3 878.3 2.58 5.00 996.7 1033.2 File Opened for Writing:124th.bwt Save results to HW/TW file:124th.bwt File Opened for Writing:124th.R51 Save results to Routing file:124th.RS1 4-28 R99095-1 340 Goldsmith& Associates Technicul hafonnation Report jor the Plat ojMa��reen Highlands SE 124`" Street Storm Drain System KCBW Model BACKWATER COMPUTER PROGRAM FOR PIPES Pipe data from file:124thpipe.bwp Surcharge condition at intermediate junctions Tailwater Elevation:515.25 feet Discharge Range:0.5 to 5. Step of 0.5 [cfs] Overflow Elevation:514.53 feet Weir:NONE Channel Width:6. feet PIPE NO. 1: 95 LF - 18"CP @ 0.16$ OUTLET: 513.98 INLET: 514.13 INTYP: 5 JUNC NO. 1: OVERFLOW-EL: 518.23 BEND: 0 DEG DIA/WIDTH: 4.0 Q-RATIO: 0.00 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ,r*,+,r*.:,r***:*,r**.<*,r***.*.*:+x*:.*�.***x***,r�,r******,r,r*,r**�***,r****+*****,r,r***,r 0.50 1.13 515.26 * 0_012 0.27 0.34 1.27 1.27 1.13 1.13 0.35 1.00 1.14 515.27 * 0.012 0.38 0.48 1.27 1.27 1.13 1.14 0.50 1.50 1.15 515.28 * 0.012 0.46 0.60 1.27 1.27 1.14 1.15 0.62 2.00 1.17 515.30 * 0.012 0.54 0.70 1.27 1.27 1.15 1.17 0.72 2.50 1.21 515.34 * 0.012 0.60 0.80 1.27 1.27 1.17 1.21 0.81 3.00 1.23 515.36 * 0.012 0.66 0.90 1.27 1.27 1.18 1.23 0.89 3.50 1.27 515.40 * 0.012 0.72 1.00 1.27 1.27 1.21 1.27 0.97 4.00 1.31 515.44 * 0.012 0.77 1.10 1.27 1.27 1.23 1.31 1.04 4.50 1.35 515.48 '� 0.012 0.82 1.23 1.27 1.27 1_26 1.35 1.11 5_0a 1.39 515.52 * 0.012 0.87 1.50 1.27 1.27 1_29 1.39 1.17 PIPE NO. 2: 110 LF - 18"CP @ 0.13$ OUTLET: 514.19 INLET: 514.33 INTYP: 5 JLTNC NO. 2: OVERFLOW-EL: 518.43 BEND: 90 DEG DIA/WZDTH: 4.0 Q-RATIO: O.OQ Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI **.+t.x,rk***+t*x*,t*****x�**x*�*.***,r:.**.*x.:rr.,t*r**,t**k:,rrr.*,t**«r**,tr,t*�***::,rx* 0.50 0.94 515.27 * 0.012 0.27 0.36 1_07 1.07 0.94 0.94 0.35 1.00 0.97 515.30 * 0.012 0.38 0.51 1.08 1.08 0.95 0.97 0.51 1.50 1.02 515.35 * 0.012 0.46 0.64 1.09 1.09 0.98 1.02 0.64 2.00 1.08 515.41 * 0.012 0.54 0.75 1.11 1.11 1_02 1.08 0.75 ! 2.50 1.16 515.49 * Q.012 0.60 0.86 1.15 1.15 1.07 1.16 0.85 3.00 1.24 515.57 * 0.012 0.66 0.96 1.17 1.17 1.12 1.24 0.95 3.50 1.33 515.66 ' 0.012 0.72 1.08 1.21 1.21 1.18 1.33 1.05 4.00 1.42 515.75 * 0.012 0.77 1.21 1.25 1.25 1.24 1.42 1.14 4.50 1.52 515.85 * 0.012 0.82 1.50 1.29 1.29 1.31 1.52 1.24 5.00 1.62 515.95 * 0.012 0.87 1.50 1.33 1.33 1.38 1.62 1.33 PIPE NO. 3: 140 LF - 18"CP @ 0.14� OUTLET: 514.48 INLET: 514.67 INTYP: 5 I� JUNC NO. 3: OVERFLOW-EL: 516.57 BEND: 0 DEG DIA/WIDTH: 4.0 Q-RATIO: 0.0� Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HV�I ******�*�********x,.*****.**,r*..*******+**,r.,r.************,r*.�.,r***+**.***,r*,r**.. . 0.50 0.63 515.30 x 0.012 0.27 0.35 0.79 0.79 0.62 0.63 0.35 1.00 0.71 515.38 * 0.012 0.38 0.50 0.82 0.82 0.67 0.71 0.51 1.50 0.81 515.48 * 0.012 0.46 0.63 0.87 0.87 0.75 0.81 0.63 2.00 0.93 515.60 * 0.012 0.54 0.73 0.93 0.93 0.84 �.93 0.74 2.50 1.04 515.71 * 0.012 0.60 0.84 1.01 1.01 0.93 1.04 0.84 3.00 1.15 515.82 * 0.012 0.66 0.94 1.09 1.09 1.03 1.15 0.93 3.50 1.27 515.94 * 0.012 0.72 1.05 1.18 1.18 1.14 1.27 1.02 4.00 1.39 516.06 * 0.012 0.77 1.18 1.27 1.27 1.25 1.39 1.11 4.5a 1.52 516.19 * 0.012 0.82 1.39 1.37 1.37 1.36 1.52 1.20 5.00 1.72 516.39 * 0.012 0.87 1.50 1.47 1.47 i.54 1.72 1.28 PIPE NO. 4: 144 LF - 18"CP @ -0.09$ CL'TLET: 514.57 INLET: 514.44 INTYP: 5 JUNC NO. 4: OVERFLOW-EL: 51/.57 BEND: 0 DEG DIA/WIDTH: 4.0 Q-RATIO: 0.00 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI «*,.**x**.*****.**************�.,r***:r********.*********,r*�****,r****:r*x,r***.«**** 0.50 0.89 515.33 * 0.012 0.27 0.00 0.73 0.73 0.88 0.89 0.35 4-29 R99095-1.340 Goldsmith& Associates Tednucnl/nformutioii Report f�r the Plat qf Maureen Hihhlui�ds 1.00 0.49 515_43 * 0.012 0.38 0.40 0.81 0.81 0.98 0.99 0.51 1.50 1.13 515.57 * 0.012 0.46 0.00 0.91 0.91 1.10 1.13 0.63 2.00 1.26 515.70 * 0.012 0.54 0_00 1_03 1.03 1.23 1.26 0.74 2.50 1.40 515.84 * 0.012 0.60 0.00 1.14 1.14 1.36 1.40 0_84 3.00 1.55 515.99 x 0.012 0_66 0.00 1.25 1.25 1.49 1.55 0.94 3.50 1.73 516.17 * 0.012 0.72 0.00 1.37 1.37 1.64 1.73 1.03 4.00 1.92 516.36 * 0.012 0.77 0.00 1.49 1.49 1.80 1.92 1.12 4.50 2.12 516.56 * 0.012 0.82 0.00 1.62 1.62 1.97 2.12 1.20 5.00 2.41 516.85 * 0.012 0.87 0.00 1.82 1.82 2.23 2.41 1.29 PIPE NO. 5: 41 LF - 18"CP @ -0.73$ OUTLET: 514.33 INLET: 514.03 INTYP: 5 Q(CFS) HW(FT) HW ELEV. * N-FAC DC DN TW DO DE HWO HWI ***************+************.**************:***************:**«**:************* **************** OVERFLOW ENCOUNTERED AT O.SO CFS DISCHARGE ***************** ****'********* ACTUAL OVERFLOW MAY OCCUR AT LESS THAN 0.50 CFS ************** 0.50 1.31 515.34 * 0.012 0.27 0.00 1.00 1.00 1.31 1.31 0.36 1.00 1.42 515.45 ' 0.012 0.38 0.00 1.10 1.10 1.41 1.42 0.51 1.50 1.58 515.61 * 0.012 0.46 0.00 1.24 1.24 1.56 1.58 0.64 2.00 1.72 515.75 * 0.012 0.54 0.00 1_37 1.37 1.69 1.72 0.75 2.50 1.88 515.91 * 0.012 0.60 0.00 1.51 1.51 1.83 1.88 0.85 3.00 2.06 516.09 * 0.012 0.66 0.00 1.66 1.66 1.99 2.06 0.94 3.50 2.27 516.30 * 0.012 0.72 0.00 1.84 1.84 2.18 2.27 1.03 4.00 2.50 516.53 * 0.012 0.77 0.00 2_03 2.03 2.38 2.50 1.12 4.50 2.75 516.78 * 0.012 0.82 0.00 2.23 2.23 2.60 2.75 1.21 5.00 3.08 517.11 * 0.012 0.87 0.00 2.52 2.52 2.90 3.08 1.30 4-30 R�)9py5-1.340 Goldsmith&Associates Tecfinica!LrJurruution Repor�Jnr the Plat u(,Lluureen Hi;h(unds �� Emergency Overflow Conditions Analysis In accordance with the 1998 KCSWDM the proposed detention ponds have been designed to safely convey flows under emergency overflow conditions. Secondary Inlet Hydraulic Calculations The KCSWDM requires a secondary inlet to the outlet control structure in additi�n to a separate emergency overflow structure. For both the Cedar River and May Creek Basin Ponds a "jail house" window is proposed for the secondary inlet and a "bird cage" overflow structure connected to the downstream conveyance system is proposed for conveying emergency pond overflows safely downstream. The primary overflow will be through the control structure riser pipe or by a baffle wall weir for the Cedar River and May Creek Ponds respectively. These structures have been conservatively designed to jointly convey the peak pond inflow rate with a 15 min. time step. Both the primary and emergency overflow have been designed to provide adequate conveyance capacity independently. Cedar River Pond Peak Pond Inflow Rates (15 minute time step): Flow Frequency Analysis Time Series File:ceddevl5.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- -----Flow Frequency Analysis------- Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 1.41 6 S/27/01 18:00 4.31 1 100.00 0.990 0.998 8 1/05/02 15: 00 3 .02 2 25 .00 0.960 3 .02 2 12/08/02 17:15 1.97 3 10.00 0.900 1.13 7 8/23/04 14:30 1.71 4 5.00 0.800 1.71 4 11/17/04 5:00 1.68 5 3 .00 0. 667 1.68 5 10/27/05 10:45 1.41 6 2 .00 0.500 1.97 3 10/25/06 22 :45 1.13 7 1.30 0.231 4.31 1 1/09/08 6:30 0.998 8 1.10 0.091 Computed Peaks 3 .88 50.00 0.980 A head requirement of 1.30 ft. is required to convey the 100-year flow of 4.31 cfs. The following calculations verify the overflow water surface of 518.10 ft. Primary Overflow Outlet Riser Riser Diameter = 12 in. Q,00 = 4.31 cfs HReq��ed = 1.30 ft. (orifice cond.) W.S. Elevation = 518.10 "Jail House" Window = 90° Manhole Diameter = 54 In. Length = 3.53 ft. 4-31 R9909�-13d0 Goldsmith & Associates Techrircal 6if��nnarion Report for the Plat nf:b9aureen Highlarids Rim Elev. = 517.0 ft. I E Out = 511.0 ft. P = 6.0 ft. C = 3.30 Q,oo = 4.31 cfs HRequired = 0.�2 ft. W.S. Elevation = 517.52 Secondary inlet overtlow water surface is controlled by the 12" riser Therefore, overflow W.S. = 518.10 ft. Emergency Overflow (Bird Cage) Hydraulic Calculations As per the 1998 KCSWDM an emergency overflow must be provided. A 48 in. "birdcage" is proposed for the Cedar River Basin pond to convey overflows to the downstream system. Manhole Diameter = 48 in. Q,00 = 4.31 cfs HRequired = �.2'3 ft. Rim Elev. = 517.50 ft. .. Emergency Overflow W.S. = 517.73 ft. May Creek Pond Peak Pond Inflow Rates (15 minute time step): ;I Flow Frequency Analysis Time Series File:mayd315.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- -----Flow Frequency Analysis------- Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob � (CFS) (CFS) Period 8.89 6 8/27/O1 18:00 27.63 1 100.00 0.990 6.35 8 1/05/02 15:00 19_35 2 25.00 0.960 19.35 2 12/08/02 17:15 12.39 3 10.00 0.900 ' 7.16 7 S/23/04 14:3� 10.73 4 5.0� 0.800 � 10.73 4 11/17/04 5:00 10.65 5 3.00 0.667 10.65 5 10/27/05 10:45 8.89 6 2.00 0.500 12.39 3 10/25/06 22:45 7.16 7 1.34 0.231 27.63 1 1/09/08 6:3� 6.35 8 1.10 0.091 Computed Peaks 24.87 50.00 0.980 A head requirement of 1.14 ft. is required to convey the 100-year flow of 27.63 cfs. The following calculations verify the overflow water surface of 521.54 ft. 4-32 R99095-1.340 Goldsmith & Associates Technical InJi�r�iiation Report for the Plcu aj�hlaureen Hi�;hlcirtds Primary Overflow Baffle Wali Weir Control Structure Diameter = 84 in. Weir Length = 7 ft. Weir Elevation = 520.40 I E Out = 515.50 P = 4.9 ft. C = 3.34 Q,� = 27.63 cfs HRequired = 1.14 ft. I W.S. Elevation = 521.54 ft. "Jail House" Window 0 = 160° Manhole Diameter = 84 In. Length = 9.77 ft. Rim Elev. = 520.60 ft. IE Out = 515.50 ft. P = 5.1 ft. C = 3.32 Q,� = 27.63 cfs HRequired = �.91 ft. W.S. Elevation = 521.51 Secondary inlet overflow water surface is controlled by the baffle wall weir. Therefore, overflow W.S. = 521.54 ft. Emergency Overflow (Bird Cage) Hydraulic Calculations As per the 1998 KCSWDM an emergency overflow must be provided. A 96 in. "birdcage" is proposed for the May Creek Basin pond to convey overflows to the downstream system. Manhole Diameter = 96 in. Q,� = 27.63 cfs HReq�;�ed = 0.50 ft. Rim Elev. = 521.0 ft. .. Emergency Overflow W.S. = 521.50 ft. 4-33 R99095-1340 Goldsmith& Associates Technical/nformatron Report jor the Plat ojMaureen Highlands Part E: Water Quality System Water quality control will be provided by the two proposed combination detention / wetpond facilities. Cedar River Basin Wetpond Sizing Calculations Tributary Area: Till Forest (ATF) = 0.00 Ac. Till Grass (ATG) = 1.62 Ac. Impervious (A;) = 2.96 Ac. Total Area = 4.58 Ac. Step 1: Basic Wetpond Volume Factor (f) = 3 Step 2: Mean Annual Storm (R) = 0.47 in. (KCSWDM Figure 6.4.1.A) Step 3: Mean Annual Runoff (V�) V, = 1�(0.9 A� + 0.25 AT� + O.1 ATF� V, _ �l� (0.9(2.96) + 0.25 (1.62) + 0.1 (0.0)) V� = 0.12 ac.-ft. Step 4/5: Vb = f V, = 3(0.12) = 0.36 ac.-ft. Cedar River Facility Water Quality Stage-Storage Table Elevation (ft.) Area(sf) Volume(c� Cumulative Volume(cf) 506.0 1002 0 0 507.0 1549 1,276 1,276 508.0 2679 2,114 3,390 � 510.0 4623 7,302 10,692 511.0 5781 5,202 15,894 � Designed Water Quality Volume = 0.37 ac.-ft. - EI. 506.0 ft. to 511.0 ft. Designed Vb/1/� = 3.1 First Cell Volume = 0.13 ac.-ft. (36% of total acre water volume). Flow Path Length to Width Verification: I�, The Cedar River pond has been verified to be greater than 3:1. � Distance from closest inlet to outlet 131 ft. � Average pond width = 28 ft. I, Flow length to width ratio = 4.7 4-34 R9909i-1.340 Goldsmith K Associates Technicnl In(onnurinn Report jor the Plut of Afuureen Hi,Khlmids May Creek Basin Wetpond Sizing Calculations Tributary Area: Till Forest (ATF) = 0.00 Ac. Till Grass (ATG) = 14.81 Ac. Impervious (A;) = 18.66 Ac. Total Area = 33.47 Ac. Step 1: Basic Wetpond Volume Factor (f) = 3 Step 2: Mean Annual Storm (R) = 0.47 in. (KCSWDM Figure 6.4.1.A) Step 3: Mean Annual Runoff (V�) V� = 1� (0.9 A; + 0.25 ATG + 0.1 ArF) V, _ �i 2� (0.9(18.66) + 025 (14.81) + 0.1 (0.0)) V� = 0.80 ac.-ft. Step 4/5: Vb = f V� = 3(0.80) = 2.40 ac.-ft. May Creek facility Water Gluality Stage-Storage Table Elevation (ft.) Area(sf) Volume(cf) Cumulative Volume(cf) � 510.0 60,259 0 0 512.0 65,979 126,238 126,238 514.0 71,909 137,888 264,126 515.5 76,206 111,086 375,212 Designed Water Quality Volume = 8.61 ac.-ft. - EI. 510.0 ft. to 515.5 ft. Designed Vb/V� = 10.8 Flow Path Length to Width Ratio Verification: Based on the designed pond geometry and the required water quality volume of 2.40 ac.-ft., the flow path criteria specified by the KCSWDM has been met. This flow path criteria is to prevent plug flow when inadequate travel time through the pond is not provided. The designed water quality pond volume provides excess volume by effectively increasing the pond width. This effectively reduces the length to width ratio to less than 3:1. However, the proposed pond design will provide adequate travel time, thereby marking the intent of the KCSWDM. Two baffle walls placed between the two inflow pipes and the outlet will ensure short circuiting of the pond is prevented. These two baffle walls create an average flow length of 273 feet. If the water quality pond was constructed to only be 2.40 ac.-ft. in size as required, it would have an average width of about 90 feet. Therefore, the average flow length of 273 feet would provide a flow length to width ratio of 3 for the 2.40 ac.-ft. water quality pond. 4-35 R99095-1.340 Goldsmith&Associates Technrcal lnforn:arion Report for the Plat ojMaureen Highlands 5. Conveyance System Analysis and Design All conveyance systems for Maureen Highlands have been analyzed and designed to meet the design requirements for runoff control, conveyance capacity and water quality control. Adequate capacity to con�ey peak rate runoff and adherence to all applicable system composition requirements are incorporated within the design. This section demonstrates compliance with an analysis of conveyance capacity for the retention/detention facilities and the storm sewer network. Spill control structure sizing calculations are at the end of this report section. The project site has been separated into five proposed drainage sub-basins, shown on Exhibits SD-1 and SD-2 along with individual catchment areas and runoff coefficients. The five sub-basins are analyzed and presented below. Storm sewer capacity analysis is based on the following assumptions: 1. The Modified Rational Method and the SBUH method is used to analyze and size the conveyance system. The SBUH method is used for the conveyance elements with a tributary area over 10 acres in size. The method used is in conformance with Section 4.2.12. of the 1998 King County Surface Water Design Manual. 2a. Runoff Coefficients-"C'values for the Rational Method used are: C = 0.90 for impervious surfaces, roofs and paving C = 025 for pervious surfaces, lawns C = 0.20 for off site grassed area 2b. Runoff curve numbers for SBUH method are: CN = 0.98 for impervious surfaces, roofs and paving CN = 0.85 for pervious surfaces, lawns CN = 0.76 for off site pasture areas 3. The time of concentration is based on actual catchment runoff characteristics and is equal or greater than 6.3 minutes. 4. The Mannings roughness coefficient used is for concrete or LCPE (smooth interior pipe) with n = 0.012. 5. The system analysis is performed for the 25 year-24 hour and 100 year-24 hour storm events. The rainfall intensity curves used are calculated using a Type 1A storm with precipitation = 3.5 inches for the 25 year event precipitation and = 3.9 inches for the 100 year event. 6. The conveyance system is designed to maintain the hydraulic grade line under backwater conditions to more than 0.5 ft. from the surface under the 25 year event and more than 0.0 ft under the 100 year event. 7. Cedar River Basin Pond 25 - year W.S. = 516.70 Cedar River Basin Pond 100-year W.S. =517.�0 May Creek Basin Pond 25-year W.S. = 520.� � ' May Creek Basin Pond 100-year W.S. = 520.5 " 8. Backwater calculations (attached) are performed us _ , and Analysis Program Version 6.1.018, copyright (c) 1973-2000 Pizer, Incorporated. 9. Drainage areas and the schematic storm sewer layout are shown on the attached Drainage Exhibits SD-1 and SD-2.. 5-1 R99095-1.340 Goldsmith&Associates Technical Infonnation Report for the Plat nf Maureen Highlmids HYDRAULIC GRADELINE / SURCHARGE SUMMAI�,Y The following table provides a summary of the 25-year and 100-year event frequency hydraulic gradeline (HGL) elevations. The HGL elevation at each of the proposed manhole catchbasins has been compared to the structures rim elevation to ensure the City of Renton and the 1998 KCSWDM design standards are met. These design standards specify a minimum freeboard of 0.5 feet for the 25 year event and 0.0 feet for the 100-year event. 1. For the 25-year event, the minimum freeboard is 0.24 feet. This occurs at manholes B29 and B30. However, given the location of these manholes this is considered acceptable. 2. For the 100-year event, the minimum freeboard is 0.0 feet at CB-B29 and CB-B3o.7 Note that for structures marked with an * on Table 5-1, the SBUH method was used for hydraulic calculations. 5-3 R99095-1340 Goldsmith&Associates Tec/inical/nfornwtion Report for the Plat of Maureen Nighlands Table 5-1 Hydraulic Gradeline Calculation Summary Structure Rim Elev. HGL Freeboard HGL Freeboard ID (ft) 25-yr (ft) 25-yr (ft) 100-yr (ft) 100-yr (ft) A1 522.65 520.34 2.31 520.74 1.91 A2 522.37 520.35 2.02 520.74 1.63 A3 522.02 520.36 1.66 520.76 1.26 A4 522.02 520.39 1.63 520.79 1.23 A5 521.27 520.39 0.88 520.79 0.48 A6 521.86 520.45 1.41 520.87 0.99 A7 521.86 520.45 1.41 520.88 0.98 A8 524.99 520.62 4.37 521.09 3.90 A9 523.50 520.69 2.81 521.16 2.34 A10 523.50 520.69 2.81 521.17 2.33 A11 521.89 520.72 1.17 521.21 0.68 Al2 525.25 520.91 4.34 521.46 3.79 A13 524.28 521.09 3.19 521.67 2.61 A14 524.28 521.10 3.18 521.68 2.60 A15 522.67 521.12 1.55 521.71 0.96 A16 525.25 521.31 3.94 521.96 3.29 A17 524.28 521.38 2.90 522.04 2.24 A1 S 524.28 521.39 2.89 522.05 2.23 A19 522.67 521.41 1.26 522.08 0.59 A20 526.48 521.53 4.95 522.23 4.25 A21 525.73 521.86 3.87 522.63 3.11 A22 524.39 522.63 1.76 523.58 0.81 A23 524.39 522.63 1.76 523.59 0.80 A24 526.22 523.66 2.56 523.83 2.39 61 521.38 520.32 1.06 520.71 0.67 62 521.38 520.32 1.06 520.71 0.67 63 521.71 520.46 1.25 520.88 0.83 64 521.71 520.46 1.25 520.89 0.83 i 65 522.09 520.59 1.50 521 A5 1.04 I B6 522.46 520.71 1.75 521.20 1.26 B7 522.46 520.71 1.75 521.20 1.26 B8 523.22 521.16 2.06 521.75 1.47 ' B9 523.22 521.16 2.06 521.75 1.47 ' 610 523.60 521.45 2.15 522.11 1.49 B11 523.98 521.73 2.25 522.44 1.54 I B 12 523.98 521.73 2.25 522.44 1.54 I B13 524J3 522.28 2.45 523.11 1.62 , 614 524J3 522.28 2.45 523.11 1.62 ' B 15 525.47 522.89 2.58 523.88 1.59 B 16 526.00 523.44 2.56 524.55 1.46 ' B 17 526.25 523.70 2.55 524.85 1.40 B 18 526.94 523.94 3.00 525.06 1.89 B 19 526.94 524.20 2.74 525.06 1.88 620 526.59 523.90 2.69 525.10 1.49 621 526.86 524.46 2.40 525.79 1.07 B22 526.86 524.46 2.40 525.79 1.07 623 527.48 525.51 1.98 527.11 0.37 ' B24 527.48 525.76 1.72 527.41 0.07 B25 528.30 525.77 2.53 527.43 0.87 B26 528.02 525.73 2.29 527.39 0.63 627 528.19 525.85 2.34 527.54 0.65 Hugh G. Goldsmith Associates Inc. 99095HGL.xis Table 5-1 Hydraulic Gradeline Calculation Summary Structure Rim Elev. HGL Freeboard HGL Freeboard ID (ft) 25-yr (ft) 25-yr (ft) 100-yr (ft) 100-yr (ft) B28 528.19 525.85 2.34 527.56 0.63 629 520.65 520.41 0.24 520.65 0.00 630 520.65 520.42 0.24 520.65 0.00 C1 523.75 520.23 3.52 520.60 3.15 * C2 523.05 520.33 2.72 520.72 2.33 * C3 523.05 520.33 2.72 520.72 2.33 * C4 526.10 520.53 5.58 520.97 5.13 * C5 524.31 520.69 3.62 521.16 3.15 C6 524.31 520.70 3.61 521.17 3.14 C7 523.72 520.77 2.95 521.26 2.46 C8 523.72 520.77 2.95 521.26 2.46 C9 522.93 520.84 2.09 521.35 1.58 C 10 522.93 520.85 2.08 521.36 1.57 C11 522.15 520.88 1.27 521.40 0.75 C12 522.15 520.89 1.26 521.42 0.73 C13 521.53 520.93 0.60 521.46 0.07 C14 521.53 520.94 0.59 521.47 0.06 C 15 523.93 521.04 2.89 521.60 2.33 C16 523.93 521.17 2.76 521.62 2.31 C17 524.46 521.37 3.09 522.02 2.44 C 18 524.46 521.62 2.84 522.02 2.44 C19 526.10 521.38 4.72 522.03 4.07 C20 524.78 521.62 3.16 522.33 2.45 C21 524.78 522.00 2.78 522.34 2.44 C22 52528 521.78 3.50 522.52 2.76 C23 525.28 522.41 2.87 522.53 2.75 C24 525.93 522.69 3.24 523.66 2.27 C25 525.93 523.11 2.82 523.67 2.26 C26 526.53 523.51 3.02 524.68 1.85 C27 526.53 523.75 2.78 524.69 1.84 C28 527.28 523.97 3.31 525.34 1.94 C29 527.28 524.54 2.74 525.36 1.92 C30 527.88 524.00 3.88 525.50 2.38 C31 528.48 525.57 2.91 526.65 1.83 C32 528.48 525.62 2.86 526.65 1.83 C33 529.23 526.46 2.77 527.78 1.46 C34 528.62 526.76 1.86 528.15 0.47 C35 528.62 526.78 1.84 528.17 0.45 D 1 521.40 517.25 4.15 517.30 4.10 D2 524.45 517.59 6.86 517.72 6.73 D3 524.45 521.55 2.90 521.55 2.90 D4 520.09 517.89 2.20 518.09 2.01 D5 519.83 518.08 1.75 518.32 1.51 D6 519.83 518.09 1.74 518.33 1.50 D7 520.38 518.56 1.82 518.92 1.46 D8 520.38 518.57 1.81 518.94 1.44 D9 520.95 518.69 2.26 519.08 1.87 D 10 520.95 518.69 2.26 519.08 1.87 E 1 518.50 517.30 1.20 517.73 0.77 E2 521.20 517.75 3.45 518.30 2.90 Hugh G. Goldsmith Associates Inc. 99095HGL.xIs • . SUB-BASIN A & C � (MAY CREEK BASIN) � Sub-basin A and C have discharge into the May Creek pond. The Rational Method was used for the backwater analysis for conveyance elements with a tributary area less than or equal to 10 acres. For elements with a tributary area � greater than 10 acres, the SBUH methology was used as per the 1998 KCSWDM. The following tables summarize the results of the 25-year and 100-year event backwater analysis for both the Rational and SBUH methods. Note the pipes analyzed using SBUYH are indicated on the Rational Method summary tables. 5-7 R9909i-]340 Goldsmith& Associates Technica!In,jonnarinn Repart(or the Plat af Nlaureen Hi�Jrlands Sub-Basin A and C 25 year (Rational Method) Backwater Analysis ID Rim Up Rim Dn IE Up IE Dn Len Diam Slope Qdes Vdes d/Diam Qfull Qexcess HGL Up HGL Dn ft ft ft ft ft in % cfs f s cfs cfs ft ft A1 TO POND 522.65 515.50 515.50 512.00 47 30 7.45% 17.76 14.64 0.29 121.57 103.81 52029 520.21 A10 TO A9 523.50 523.50 519.50 517.79 27 12 6.33% 0.55 5.80 0.19 9.74 9.19 520.69 520.69 A11 TO A9 521.89 523.50 517.89 517.29 102 18 0.59% 2.02 3.35 0.37 8.75 6.73 520.72 520.69 Al2 TO A8 525.25 524.99 516.86 515.93 310 30 0.30% 12.41 4.27 0.57 24.40 11.99 520.86 520.62 A13 TO Al2 524.28 525.25 518.36 517.86 60 18 0.83% 3.15 4.34 0.43 10.41 7.26 520.96 520.91 A14 TO A13 524.28 524.28 520.28 518.86 27 12 5.26% 0.56 5.44 0.20 8.87 8.31 521.10 521.09 A15 TO A13 522.67 524.28 519.17 518.36 102 18 0.79% 2.04 3.72 0.34 10.17 8.13 521.12 521.09 A16 TO Al2 525.25 525.25 518.25 517.36 295 24 0.30% 7.78 3.84 0.62 13.49 5.71 521.21 520.91 A17 TO A16 524.28 525.25 518.43 518.25 60 24 0.30°/a 3.23 2.94 0.38 13.46 10.23 521.32 521.31 A18 TO A17 524.28 524.28 520.28 519.43 27 12 3.15% 0.62 4.64 0.24 6.86 6.25 521.39 521.38 A19 TO A17 522.67 52428 519.24 518.93 102 18 0.30% 2.06 2.68 0.45 6.29 4.23 521.41 521.38 A2 TO A1 522.37 522.65 516.65 516.50 47 18 0.32% 0.63 1.98 0.25 6.44 5.81 520.35 520.34 A20 TO A16 526.48 525.25 519.14 518.75 130 18 0.30% 3.00 2.98 0.55 6.25 3.25 521.40 521.31 A21 TO A20 525.73 526.48 519.53 519.14 130 18 0.30% 3.00 2.98 0.55 6.25 3.25 521.62 521.53 A22 TO A21 524.39 525.73 521.13 520.03 81 12 1.36% 2.87 5.29 0.65 4.51 1.64 522.31 521.86 A23 TO A22 524.39 524.39 521.28 521.13 29 12 0.52% 0.48 2.19 0.32 2.78 2.30 522.63 522.63 A24 TO A22 526.22 524.39 523.22 521.13 97 12 2.15% 1.72 5.32 0.43 5.68 3.96 523.66 522.63 A3 TO A2 522.02 522.37 516.89 516.65 67 18 0.36% 0.46 1.89 0.21 6.83 6.37 520.35 520.35 A4 TO A3 522.02 522.02 517.54 517.39 29 12 0.52% 0.38 2.06 0.28 2.78 2.40 520.36 520.36 A5 TO A4 521.27 522.02 518.27 517.54 146 12 0.50% 0.20 1.75 022 2.74 2.53 520.39 520.39 A6 TO A1 521.86 522.65 515.69 515.50 62 30 0.31% 17.13 4.75 0.69 24.66 7.53 520.44 520.34 A7 TO A6 521.86 521.86 518.86 517.19 25 12 6.68% 0.48 5.70 0.18 10.00 9.52 520.45 520.45 A8 TO A6 524.99 521.86 515.93 515.69 85 30 0.28% 16.04 4.53 0.68 23.67 7.63 520.56 520.45 A9 TO A8 523.50 524.99 516.79 516.43 59 24 0.61% 2.57 3.54 0.28 19.19 16.62 520.63 520.62 C1 TO POND 523.75 515.50 515.00 511.50 47 30 7.45% 19.12 14.92 0.30 121.57 102.45 520.30 520.21 C10 TO C9 522.93 522.93 518.93 517.82 27 12 4.11% 0.76 5.41 0.25 7.84 7.09 520.85 520.84 C11 TO C9 522.15 522.93 517.19 516.82 147 24 0.25% 2.94 2.68 0.38 12.33 9.39 520.86 520.84 C12 TO C11 522.15 522.15 518.55 518.19 27 12 1.33% 0.76 3.49 0.31 4.47 3.71 520.89 520.88 C13 TO C11 521.53 522.15 517.49 517.19 117 24 0.26% 1.44 2.22 0.27 12.44 11.00 520.89 520.88 C14 TO C13 521.53 521.53 518.63 518.49 27 12 0.52% 0.72 2.50 0.39 2.79 2.07 520.94 520.93 C15 TO C4 523.93 526.10 517.89 515.94 122 24 1.60% 12.13 7.85 0.49 31.06 18.93 520.90 520.61 C16 TO C15 523.93 523.93 520.93 518.89 26 12 7.85% 0.88 7.10 0.23 10.84 9.96 521.17 521.04 C17 TO C15 524.46 523.93 518.44 517.89 110 24 0.50% 10.48 5.01 0.63 17.37 6.90 521.24 521.04 C18 TO C17 524.46 524.46 521.46 519.44 27 12 7.48% 0.37 5.59 0.16 10.58 10.21 521.62 521.37 C19 TO C17 526.10 524.46 519.66 519.44 22 12 1.00% 0.75 3.15 0.34 3.87 3.12 521.38 521.37 C2 TO C1 523.05 523.75 515.03 515.00 12 30 0.25% 19.12 4.56 0.80 22.27 3.16 520.32 520.30 C20 TO C17 524.78 524.46 518.72 518.44 57 24 0.49% 9.28 4.80 0.59 17.22 7.94 521.45 521.37 C21 TO C20 524.78 524.78 521.78 519.72 27 12 7.63% 0.75 6.75 0.22 10.69 9.93 522.00 521.62 C22 TO C20 525.28 524.78 519.19 518.72 95 24 0.49% 7.81 4.56 0.53 17.28 9.47 521.72 521.62 C23 TO C22 525.28 525.28 522.23 520.19 27 12 7.56% 0.46 5.90 0.17 10.63 10.17 522.41 521.78 C24 TO C22 525.93 52528 520.33 519.69 128 18 0.50% 7.19 4.63 0.82 8.07 0.87 522.29 521.78 C25 TO C24 525.93 525.93 522.93 520.83 27 12 7.78% 0.47 5.99 0.17 10.79 10.32 523.11 522.69 C26 TO C24 526.53 525.93 520.93 520.33 120 18 0.50% 6.21 4.45 0.74 8.07 1.85 523.05 522.69 Hugh G.Goldsmith Associates Inc. 99095HYD.xIs/C25-RATIONAL-REV Sub-Basin A and C 25 year (Rational Method) Backwater Analysis ID Rim Up Rim Dn IE Up IE Dn Len Diam Slope Qdes Vdes d/Diam Qfull Qexcess HGL Up HGL Dn ft ft ft ft ft in % cfs f s cfs cfs ft ft C27 TO C26 526.53 526.53 523.53 521.43 27 12 7.78% 0.74 6.77 0.21 10.79 10.04 523.75 523.51 C28 TO C26 527.28 526.53 522.59 520.93 147 18 1.13% 4.94 5.52 0.51 12.12 7.18 523.78 523.51 C29 TO C28 527.28 527.28 524.28 523.09 29 12 4.10% 0.77 5.42 0.25 7.84 7.06 524.54 523.97 C3 TO C2 523.05 523.05 519.05 516.53 26 12 9.69% 0.18 4.97 0.11 12.04 11.87 520.55 520.55 C30 TO C28 527.88 527.28 523.18 522.59 118 18 0.50% 3.66 3.79 0.53 8.07 4.41 524.00 523.97 C31 TO C30 528.48 527.88 524.27 523.68 118 12 0.50% 3.18 4.05 1.00 2.74 -0.45 525.48 524.68 C32 TO C31 528.48 528.48 525.48 524.27 29 12 4.17% 0.20 3.82 0.14 7.90 7.70 525.62 525.57 C33 TO C31 529.23 528.48 525.01 524.27 148 12 0.50% 2.50 3.55 0.83 2.74 0.24 526.18 525.57 C34 TO C33 528.62 529.23 525.33 525.01 63 12 0.51% 1.67 3.19 0.64 2.76 1.08 526.58 526.46 C35 TO C34 528.62 528.62 525.62 525.33 29 12 1.00°/ 0.89 3.33 0.37 3.87 2.97 526.78 526.76 C4 TO C2 526.10 523.05 515.44 515.03 161 30 0.25% 18.76 4.57 0.78 22.48 3.72 520.83 520.55 C5 TO C4 524.31 526.10 516.17 515.94 89 24 0.26% 6.63 3.47 0.58 12.49 5.86 520.67 520.61 C6 TO C5 524.31 524.31 520.31 517.17 25 12 12.56% 0.47 7.21 0.16 13.71 1324 520.70 520.69 C7 TO CS 523.72 524.31 516.45 516.17 111 24 025% 5.62 3.26 0.54 12.34 6.72 520.75 520.69 C8 TO C7 523.72 523.72 519.72 517.45 26 12 8.73% 0.45 6.20 0.16 11.43 10.98 520.77 520.77 C9 TO C7 522.93 523.72 516.82 516.45 147 24 0.25% 4.44 3.04 0.47 12.33 7.89 520.81 520.77 Hugh G.Goldsmith Associates Inc. 99095HYD.xIs/C25-RATIONAL-REV I Sub-Basin A and C 100 year (Rational Method) Backwater Analysis ID Rim Up Rim Dn IE Up IE Dn Len Diam Slope Qdes Vdes d/Diam Qfull Qexcess HGL Up HGL Dn ft ft ft ft ft in % cfs f s cfs cfs ft ft At TO POND 522.65 515.50 515.50 512.00 47 30 7.45% 20.16 15.13 0.31 121.57 101.41 520.67 520.57 A10 TO A9 523.50 523.50 519.50 517.79 27 12 6.33% 0.62 6.00 0.21 9.74 9.11 521.17 521.16 A11 TO A9 521.89 523.50 517.89 517.29 102 18 0.59% 2.30 3.51 0.40 8.75 6.45 521.21 521.16 Al2 TO A8 525.25 524.99 516.86 515.93 310 30 0.30% 14.08 4.45 0.62 24.40 10.32 521.40 521.09 A13 TO Al2 524.28 525.25 518.36 517.86 60 18 0.83% 3.58 4.50 0.46 10.41 6.83 521.51 521.46 A14 TO A13 524.28 524.28 520.28 518.86 27 12 5.26% 0.63 5.62 0.22 8.87 8.24 521.68 521.67 A15 TO A13 522.67 524.28 519.17 518.36 102 18 0.79% 2.32 3.87 0.37 10.17 7.85 521.71 521.67 A16 TO Al2 525.25 525.25 518.25 517.36 295 24 0.30% 8.84 3.99 0.67 13.49 4.66 521.84 521.46 A17 TO A16 524.28 525.25 518.43 518.25 60 24 0.30% 3.67 3.07 0.41 13.46 9.79 521.97 521.96 A18 TO A17 524.28 524.28 52028 519.43 27 12 3.15% 0.70 4.78 026 6.86 6.16 522.05 522.04 A19 TO A17 522.67 524.28 519.24 518.93 102 18 0.30% 2.34 2.78 0.48 6.29 3.95 522.08 522.04 A2 TO A1 522.37 522.65 516.65 516.50 47 18 0.32% 0.72 2.03 026 6.44 5.73 520.74 520.74 A20 TO A16 526.48 525.25 519.14 518.75 130 18 0.30% 3.40 3.11 0.59 6.25 2.85 522.07 521.96 A21 TO A20 525.73 526.48 519.53 519.14 130 18 0.30% 3.40 3.11 0.59 6.25 2.85 522.34 522.23 A22 TO A21 524.39 525.73 521.13 520.03 81 12 1.36% 3.26 5.49 0.71 4.51 1.25 523.20 522.63 A23 TO A22 524.39 524.39 521.28 521.13 29 12 0.52% 0.54 227 0.34 2.78 2.24 523.59 523.58 A24 TO A22 526.22 524.39 523.22 521.13 97 12 2.15% 1.95 5.52 0.46 5.68 3.73 523.83 523.58 A3 TO A2 522.02 522.37 516.89 516.65 67 18 0.36% 0.52 1.95 0.22 6.83 6.31 520.74 520.74 A4 TO A3 522.02 522.02 517.54 517.39 29 12 0.52% 0.43 2.12 0.30 2.78 2.35 520.76 520.76 A5 TO A4 521.27 522.02 518.27 517.54 146 12 0.50% 0.23 1.81 0.23 2.74 2.51 520.79 520.79 A6 TO A1 521.86 522.65 515.69 515.50 62 30 0.31% 19.44 4.93 0.75 24.66 522 520.85 520.74 A7 TO A6 521.86 521.86 518.86 517.19 25 12 6.68% 0.55 5.90 0.19 10.00 9.45 520.88 520.87 A8 TO A6 524.99 521.86 515.93 515.69 85 30 0.28% 18.21 4.70 0.74 23.67 5.46 521.01 520.87 A9 TO A8 523.50 524.99 516.79 516.43 59 24 0.61% 2.92 3.65 0.30 19.19 16.27 521.10 521.09 C1 TO POND 523.75 515.50 515.00 511.50 47 30 7.45% 21.78 15.46 0.32 121.57 99.79 520.68 520.57 C10 TO C9 522.93 522.93 518.93 517.82 27 12 4.11% 0.86 5.54 0.26 7.84 6.99 521.36 521.35 C11 TO C9 522.15 522.93 517.19 516.82 147 24 0.25% 3.34 2.80 0.40 12.33 8.99 521.38 521.35 C12 TO C11 522.15 522.15 518.55 518.19 27 12 1.33% 0.86 3.62 0.33 4.47 3.61 521.42 521.40 C13 TO C11 521.53 522.15 517.49 517.19 117 24 0.26% 1.64 2.28 0.28 12.44 10.80 521.41 521.40 C14 TO C13 521.53 521.53 518.63 518.49 27 12 0.52% 0.82 2.59 0.42 2.79 1.97 521.47 521.46 C75 TO C4 523.93 526.10 517.89 515.94 122 24 1.60% 13.85 8.16 0.53 31.06 17.21 521.44 521.05 C16 TO C15 523.93 523.93 520.93 518.89 26 12 7.85% 1.00 7.37 0.25 10.84 9.84 521.62 521.60 C17 TO C15 524.46 523.93 518.44 517.89 110 24 0.50% 11.97 5.22 0.69 17.37 5.40 521.86 521.60 C18 TO C17 524.46 524.46 521.46 519.44 27 12 7.48% 0.42 5.75 0.17 10.58 10.16 522.02 522.02 C19 TO C17 526.10 524.46 519.66 519.44 22 12 1.00% 0.87 3.30 0.36 3.87 3.00 522.03 522.02 C2 TO C 1 523.05 523.75 515.03 515.00 12 30 0.25% 21.78 4.70 0.89 22.27 0.50 520.71 520.68 C20 TO C17 524.78 524.46 518.72 518.44 57 24 0.49% 10.59 5.00 0.64 17.22 6.63 522.13 522.02 C21 TO C20 524.78 524.78 521.78 519.72 27 12 7.63% 0.85 6.98 0.23 10.69 9.83 522.34 522.33 C22 TO C20 525.28 524.78 519.19 518.72 95 24 0.49% 8.92 4.75 0.58 17.28 8.36 522.45 522.33 C23 TO C22 525.28 525.28 522.23 520.19 27 12 7.56% 0.52 6.09 0.18 10.63 10.11 522.53 522.52 C24 TO C22 525.93 525.28 520.33 519.69 129 18 0.50% 8.22 4.65 1.00 8.07 -0.16 523.19 522.52 C25 TO C24 525.93 525.93 522.93 520.83 27 12 7.78% 0.53 6.19 0.18 10.79 10.25 523.67 523.66 C26 TO C24 526.53 525.93 520.93 520.33 120 18 0.50% 7.10 4.62 0.81 8.07 0.96 524.13 523.66 Hugh G.Goldsmith Associates Inc. 99095HYD.xIs/C100-RATIONAL-REV I Sub-Basin A and C 100 year (Rational Method) Backwater Analysis ID Rim Up Rim Dn IE Up IE Dn Len Diam Slope Qdes Vdes d/Diam Qfull Qexcess HGL Up HGL Dn ft ft ft ft ft in % cfs f s cfs cfs ft ft C27 TO C26 526.53 526.53 523.53 521.43 27 12 7.78% 0.84 7.00 0.23 10.79 9.94 524.69 524.68 C28 TO C26 52728 526.53 522.59 520.93 147 18 1.13% 5.65 5.73 0.54 12.12 6.48 525.04 524.68 C29 TO C28 527.28 527.28 524.28 523.09 29 12 4.10% 0.88 5.56 0.26 7.84 6.96 525.36 525.34 C3 TO C2 523.05 523.05 519.05 516.53 26 12 9.69% 0.20 5.13 0.11 12.04 11.84 520.98 520.98 C30 TO C28 527.88 52728 523.1 S 522.59 118 18 0.50% 4.18 3.95 0.58 8.07 3.88 525.50 525.34 C31 TO C30 528.48 527.88 524.27 523.68 118 12 0.50% 3.64 4.63 1.00 2.74 -0.90 526.54 525.50 C32 TO C31 528.48 528.48 525.48 524.27 29 12 4.17% 0.23 3.98 0.15 7.90 7.67 526.65 526.65 C33 TO C31 529.23 528.48 525.01 524.27 148 12 0.50% 2.85 3.63 1.00 2.74 -0.11 527.45 526.65 C34 TO C33 528.62 529.23 525.33 525.01 63 12 0.51% 1.90 3.31 0.69 2.76 0.86 527.93 527.78 C35 TO C34 528.62 528.62 525.62 525.33 29 12 1.00% 1.02 3.49 0.40 3.87 2.85 528.17 528.15 C4 TO C2 526.10 523.05 515.44 515.03 161 30 0.25% 21.37 4.71 0.86 22.48 1.11 521.35 520.98 C5 TO C4 524.31 526.10 516.17 515.94 89 24 0.26% 7.53 3.60 0.63 12.49 4.96 521.14 521.05 C6 TO C5 524.31 524.31 520.31 517.17 25 12 12.56% 0.53 7.42 0.16 13.71 13.17 521.17 521.16 C7 TO CS 523.72 524.31 516.45 516.17 111 24 0.25% 6.38 3.39 0.58 12.34 5.96 521.24 521.16 C8 TO C7 523.72 523.72 519.72 517.45 26 12 8.73% 0.51 6.39 0.17 11.43 10.92 521.26 521.26 C9 TO C7 522.93 523.72 516.82 516.45 147 24 0.25% 5.04 3.16 0.51 12.33 7.29 521.32 521.26 Hugh G.Goldsmith Associates Inc. 99095HYD.xIs/C100-RATIONAL-REV Sub-Basin A and C 25 year (SBUH Method) Backwater Analysis ID Rim Up Rim Dn IE Up IE Dn Len Diam Slope Qdes Vdes d/Diam Qfull Qexcess HGL Up HGL Dn ft ft ft ft ft in % cfs f s cfs cfs ft ft A1 TO POND 522.65 515.50 515.50 512.00 47 30 7.45% 7.46 11.87 0.20 121.57 114.11 520.22 520.21 A10 TO A9 523.50 523.50 519.50 517.79 27 12 6.33% 024 4.64 0.13 9.74 9.50 520.33 520.32 At 1 TO A9 521.89 523.50 517.89 51729 102 18 0.59% 0.85 2.68 0.25 8.75 7.90 520.33 520.32 Al2 TO A8 525.25 524.99 516.86 515.93 310 30 0.30% 5.26 3.29 0.36 24.40 19.14 520.35 520.30 A13 TO Al2 524.28 525.25 518.36 517.86 60 18 0.83% 1.33 3.38 028 10.41 9.08 520.37 520.36 A14 TO A13 524.28 524.28 520.28 518.86 27 12 5.26°/ 0.24 4.35 0.14 8.87 8.63 520.42 520.42 A15 TO A13 522.67 524.28 519.17 518.36 102 18 0.79% 0.86 3.00 0.24 10.17 9.31 520.42 520.42 A16 TO Al2 525.25 525.25 518.25 517.36 295 24 0.30% 3.30 2.97 0.38 13.49 10.19 520.42 520.36 A17 TO Ai6 524.28 525.25 518.43 518.25 60 24 0.30°/ 1.36 2.34 0.26 13.46 12.09 520.45 520.45 A18 TO A17 524.28 524.28 520.28 519.43 27 12 3.15% 0.26 3.69 0.16 6.86 6.60 520.47 520.47 A19 TO A17 522.67 524.28 519.24 518.93 102 18 0.30% 0.87 2.07 029 6.29 5.42 520.48 520.47 A2 TO A1 522.37 522.65 516.65 516.50 47 18 0.32% 0.22 1.50 0.16 6.44 6.23 520.24 520.24 ' A20 TO A16 526.48 525.25 519.14 518.75 130 18 0.30% 1.28 2.30 0.35 6.25 4.97 520.47 520.45 A21 TO A20 525.73 526.48 519.53 519.14 130 18 0.30% 1.28 2.30 0.35 6.25 4.97 520.50 520.50 A22 TO A21 524.39 525J3 521.13 520.03 81 12 1.36% 1.23 4.11 0.41 4.51 3.27 521.55 520.57 I A23 TO A22 524.39 524.39 52128 521.13 29 12 0.52% 0.23 1.82 0.23 2.78 2.56 521.73 521.73 ' A24 TO A22 526.22 524.39 523.22 521.13 97 12 2.15% 0.74 4.15 0.28 5.68 4.94 523.50 521.73 A3 TO A2 522.02 522.37 516.89 516.65 67 18 0.36% 0.16 1.42 0.13 6.83 6.67 52024 520.24 A4 TO A3 522.02 522.02 517.54 517.39 29 12 0.52% 0.13 1.58 0.18 2.78 2.65 520.25 520.25 A5 TO A4 521.27 522.02 518.27 517.54 146 12 0.50% 0.07 1.32 0.14 2.74 2.67 520.25 520.25 A6 TO A1 521.86 522.65 515.69 515.50 62 30 0.31% 7.24 3.67 0.42 24.66 17.42 52026 520.24 A7 TO A6 521.86 521.86 518.86 517.19 25 12 6.68% 021 4.55 0.12 10.00 9.79 520.26 520.26 A8 TO A6 524.99 521.86 515.93 515.69 85 30 0.28% 6.80 3.50 0.42 23.67 16.87 520.28 520.26 A9 TO A8 523.50 524.99 516.79 516.43 59 24 0.61% 1.09 2.86 0.19 19.19 18.10 520.30 520.30 C1 TO POND 523.75 515.50 575.00 511.50 47 30 7.45% 9.51 12.62 0.23 121.57 112.06 520.23 520.21 C10 TO C9 522.93 522.93 518.93 517.82 27 12 4.11% 0.31 4.26 0.17 7.84 7.53 520.58 520.57 C11 TO C9 522.15 522.93 517.19 516.82 147 24 0.25% 1.21 2.13 0.25 12.33 11.12 520.58 520.57 C12 TO C11 522.15 522.15 518.55 518.19 27 12 1.33% 0.31 2.82 0.21 4.47 4.15 520.59 520.59 C13 TO C11 521.53 522.15 517.49 517.19 117 24 026% 0.59 1.77 0.18 12.44 11.85 520.59 520.59 C14 TO C13 521.53 521.53 518.63 518.49 27 12 0.52% 0.30 1.96 0.26 2.79 2.48 520.60 520.60 C15 TO C4 523.93 526.10 517.89 515.94 122 24 1.60% 6.70 6.54 0.36 31.06 24.36 520.62 520.53 C16 TO C15 523.93 523.93 520.93 518.89 26 12 7.85% 0.36 5.66 0.15 10.84 10.48 521.09 520.66 C17 TO C15 524.46 523.93 518.44 517.89 110 24 0.50% 6.02 423 0.46 17.37 11.36 520.73 520.66 C18 TO C17 524.46 524.46 521.46 519.44 27 12 7.48% 0.16 4.40 0.11 10.58 10.42 521.58 520.80 C19 TO C17 526.10 524.46 519.66 519.44 22 12 1.00% 0.80 3.22 0.35 3.87 3.06 520.81 520.80 C2 TO Ct 523.05 523.75 515.03 515.00 12 30 0.25% 9.51 3.70 0.52 22.27 12.77 520.24 520.23 I C20 TO C17 524.78 524.46 518.72 518.44 57 24 0.49% 5.03 3.99 0.42 17.22 12.19 520.82 520.80 C21 TO C20 524.78 524.78 521.78 519.72 27 12 7.63% 0.33 5.48 0.15 10.69 10.36 521.94 520.89 C22 TO C20 525.28 524.78 519.19 518.72 95 24 0.49% 4.40 3.85 0.39 17.28 12.88 520.92 520.89 C23 TO C22 525.28 525.28 522.23 520.19 27 12 7.56% 0.20 4.68 0.12 10.63 10.43 522.35 520.94 C24 TO C22 525.93 525.28 520.33 519.69 128 18 0.50% 4.15 3.94 0.57 8.07 3.92 521.21 520.94 C25 TO C24 525.93 525.93 522.93 520.83 27 12 7.78% 0.20 4.71 0.12 10.79 10.59 523.05 521.41 C26 TO C24 526.53 525.93 520.93 520.33 120 18 0.50% 3.55 3.75 0.53 8.07 4.52 521.73 521.41 Hugh G.Goldsmith Assoclates Inc. 99095HYD.xIs/C25-SBUH-REV Sub-Basin A and C 25 year (SBUH Method) Backwater Analysis ID Rim Up Rim Dn IE Up IE Dn Len Diam Slope Qdes Vdes d/Diam Qfull Qexcess HGL Up HGL Dn ft ft ft ft ft in % cfs f s cfs cfs ft ft C27 TO C26 526.53 526.53 523.53 521.43 27 12 7.78% 0.32 5.47 0.15 10.79 10.47 523.69 522.00 C28 TO C26 527.28 526.53 522.59 520.93 147 18 1.13% 2.81 4.65 0.37 12.12 9.31 523.15 522.00 C29 TO C28 527.28 527.28 524.28 523.09 29 12 4.10% 0.31 4.24 0.16 7.84 7.53 524.46 523.38 C3 TO C2 523.05 523.05 519.05 516.53 26 12 9.69% 0.06 3.27 0.06 12.04 11.98 520.33 520.33 C30 TO C28 527.88 527.28 523.18 522.59 118 18 0.50% 2.11 3.23 0.40 8.07 5.96 523.78 523.38 C31 TO C30 528.48 527.88 524.27 523.68 118 12 0.50°/ 1.77 3.23 0.66 2.74 0.96 524.95 524.36 C32 TO C31 528.48 528.48 525.48 524.27 29 12 4.17°/ 0.07 2.73 0.08 7.90 7.83 525.58 524.97 C33 TO C31 529.23 528.48 525.01 52427 148 12 0.50% 1.35 2.97 0.56 2.74 1.38 525.59 524.97 C34 TO C33 528.62 529.23 525.33 525.01 63 12 0.51% 0.67 2.42 0.38 2J6 2.09 525J3 525.71 � C35 TO C34 528.62 528.62 525.62 525.33 29 12 1.00% 0.37 2.66 0.25 3.87 3.50 525.88 525.83 ' C4 TO C2 526.10 523.05 515.44 515.03 161 30 0.25% 9.39 3.71 0.51 22.48 13.09 520.40 520.33 C5 TO C4 524.31 526.10 516.17 515.94 89 24 0.26% 2.69 2.63 0.36 12.49 9.80 520.54 520.53 C6 TO C5 524.31 524.31 520.31 517.17 25 12 12.56% 0.17 5.42 0.10 13.71 13.54 520.54 520.54 C7 TO C5 523.72 524.31 516.45 516.17 111 24 0.25°/ 2.30 2.48 0.33 12.34 10.04 520.55 520.54 C8 TO C7 523.72 523.72 519.72 517.45 26 12 8.73% 0.19 4.85 0.11 11.43 11.24 520.56 520.56 C9 TO C7 522.93 523.72 516.82 516.45 147 24 0.25% 1.82 2.33 029 12.33 10.50 520.57 520.56 Hugh G.Goldsmith Associates Inc. 99095HYD.xIs/C25•SBUH-REV Sub-Basin A and C 100 year (SBUH Method) Backwater Analysis ID Rim Up Rim Dn IE Up IE Dn Len Diam Slope Qdes Vdes d/Diam Qfull Qexcess HGL Up HGL Dn ft ft ft ft ft in % cfs f s cfs cfs ft ft A1 TO POND 522.65 515.50 515.50 512.00 47 30 7.45% 8.55 1227 022 121.57 113.01 520.59 520.57 A10 TO A9 523.50 523.50 519.50 517.79 27 12 6.33% 0.27 4.85 0.14 9.74 9.46 520.71 520.71 A11 TO A9 521.89 523.50 517.89 51729 102 18 0.59% 0.98 2.76 0.26 8.75 7.77 520.72 520.71 Al2 TO A8 525.25 524.99 516.86 515.93 310 30 0.30% 6.04 3.45 0.38 24.40 18.36 520.74 520.69 A13 TO Al2 524.28 525.25 518.36 517.86 60 18 0.83% 1.53 3.49 029 10.41 8.88 520.77 520.76 A14 TO A13 524.28 524.28 520.28 518.86 27 12 5.26% 0.27 4.57 0.15 8.87 8.60 520.83 520.83 A15 TO A13 522.67 524.28 519.17 518.36 102 18 0.79% 0.99 3.12 025 10.17 9.18 520.84 520.83 A16 TO Al2 525.25 525.25 518.25 517.36 295 24 0.30°/ 3.79 3.10 0.41 13.49 9.70 520.83 520.76 A17 TO A16 524.28 525.25 518.43 518.25 60 24 0.30% 1.57 2.40 0.27 13.46 11.89 520.88 520.87 A18 TO A17 524.28 524.28 520.28 519.43 27 12 3.15% 0.30 3.81 0.17 6.86 6.57 520.90 520.90 A19 TO A17 522.67 524.28 519.24 518.93 102 18 0.30% 0.99 2.15 0.30 629 529 520.91 520.90 A2 TO A1 522.37 522.65 516.65 516.50 47 18 0.32% 0.24 1.54 0.16 6.44 6.20 520.61 520.61 A20 TO A16 526.48 525.25 519.14 518.75 130 18 0.30°/ 1.47 2.41 0.37 6.25 4.78 520.90 520.87 A21 TO A20 525.73 526.48 519.53 519.14 130 18 0.30% 1.47 2.41 0.37 6.25 4.78 520.97 520.95 A22 TO A21 524.39 525.73 521.13 520.03 81 12 1.36% 1.42 4.27 0.44 4.51 3.09 521.57 521.03 A23 TO A22 524.39 524.39 521.28 521.13 29 12 0.52% 0.26 1.91 0.25 2.78 2.52 521.78 521.78 A24 TO A22 526.22 524.39 523.22 521.13 97 12 2.15% 0.85 4.29 0.30 5.68 4.83 523.52 521.78 A3 TO A2 522.02 522.37 516.89 516.65 67 18 0.36% 0.18 1.47 0.14 6.83 6.65 520.61 520.61 A4 TO A3 522.02 522.02 517.54 517.39 29 12 0.52% 0.15 1.62 0.19 2.78 2.64 520.61 520.61 A5 TO A4 521.27 522.02 518.27 517.54 146 12 0.50% 0.08 1.37 0.14 2.74 2.66 520.62 520.61 A6 TO A1 521.86 522.65 515.69 515.50 62 30 0.31% 8.31 3.81 0.45 24.66 16.35 520.63 520.61 A7 TO A6 521.86 521.86 518.86 517.19 25 12 6.68% 0.24 4.74 0.13 10.00 9.76 520.64 520.64 A8 TO A6 524.99 521.86 515.93 515.69 85 30 0.28% 7.80 3.63 0.45 23.67 15.87 520.66 520.64 A9 TO A8 523.50 524.99 516.79 516.43 59 24 0.61% 1.25 2.97 0.21 19.19 17.94 520.69 520.69 C1 TO POND 523.75 515.50 515.00 511.50 47 30 7.45% 10.96 13.16 024 121.57 110.61 520.60 520.57 C10 TO C9 522.93 522.93 518.93 517.82 27 12 4.11% 0.36 4.41 0.18 7.84 7.49 521.03 521.03 Ci i TO C9 522.15 522.93 517.19 516.82 147 24 0.25% 1.38 2.19 0.26 12.33 10.94 521.03 521.03 C12 TO C11 522.15 522.15 518.55 518.19 27 12 1.33% 0.36 2.92 0.23 4.47 4.11 521.04 521.04 C13 TO C11 521.53 522.15 517.49 517.19 117 24 0.26% 0.68 1.83 0.19 12.44 11.76 521.04 521.04 C14 TO C13 521.53 521.53 518.63 518.49 27 12 0.52% 0.34 2.02 027 2.79 2.44 521.06 521.06 C15 TO C4 523.93 526.10 517.89 515.94 122 24 1.60% 7.75 6.88 0.39 31.06 23.31 521.09 520.97 C16 TO C15 523.93 523.93 520.93 518.89 26 12 7.85% 0.41 5.83 0.16 10.84 10.42 521.14 521.14 C17 TO C15 524.46 523.93 518.44 517.89 110 24 0.50% 6.97 4.43 0.50 17.37 10.40 521.23 521.14 C18 TO C17 524.46 524.46 521.46 519.44 27 12 7.48% 0.18 4.56 0.11 10.58 10.40 521.58 521.32 C19 TO C17 526.10 524.46 519.66 519.44 22 12 1.00% 0.96 3.42 0.39 3.87 2.90 521.33 521.32 C2 TO C1 523.05 523.75 515.03 515.00 12 30 0.25% 10.96 3.86 0.56 2227 11.31 520.61 520.60 C20 TO C17 524.78 524.46 518.72 518.44 57 24 0.49% 5.80 4.16 0.45 17.22 11.42 521.35 521.32 C21 TO C20 524.78 524.78 521.78 519.72 27 12 7.63% 0.38 5.65 0.16 10.69 10.31 521.94 521.43 C22 TO C20 525.28 524.78 519.19 518.72 95 24 0.49% 5.07 4.01 0.42 17.28 1221 521.47 521.43 C23 TO C22 525.28 52528 522.23 520.19 27 12 7.56% 0.23 4.87 0.12 10.63 10.41 522.37 521.50 C24 TO C22 525.93 525.28 520.33 519.69 128 18 0.50% 4.79 4.12 0.63 8.07 3.28 521.72 521.50 C25 TO C24 525.93 525.93 522.93 520.83 27 12 7.78% 0.23 4.91 0.12 10.79 10.56 523.07 521.87 C26 TO C24 526.53 525.93 520.93 520.33 120 18 0.50% 4.10 3.92 0.57 8.07 3.97 522.03 521.87 Hugh G.Goldsmith Associates Inc. 99095HYD.xIs/C100-SBUH-REV I Sub-Basin A and C 100 year (SBUH Method) Backwater Analysis ID Rim Up Rim Dn IE Up IE Dn Len Diam Slope Qdes Vdes d/Diam Qfull Qexcess HGL Up HGL Dn ft ft ft ft ft in % cfs f s cfs cfs ft ft ' C27 TO C26 526.53 526.53 523.53 521.43 27 12 7.78% 0.36 5.66 0.16 10.79 10.42 523.69 522.25 C28 TO C26 527.28 526.53 522.59 520.93 147 18 1.13% 3.25 4.89 0.40 12.12 8.87 523.21 522.25 C29 TO C28 527.28 527.28 524.28 523.09 29 12 4.10% 0.35 4.38 0.17 7.84 7.49 524.46 523.45 I C3 TO C2 523.05 523.05 519.05 516.53 26 12 9.69% 0.07 3.43 0.07 12.04 11.97 520.72 520.72 I C30 TO C28 527.88 527.28 523.18 522.59 118 18 0.50% 2.44 3.36 0.43 8.07 5.63 523.84 523.45 �I C31 TO C30 528.48 527.88 524.27 523.68 118 12 0.50°/a 2.05 3.37 0.73 2.74 0.69 525.01 524.42 C32 TO C31 528.48 528.48 525.48 524.27 29 12 4.17% 0.08 2.83 0.09 7.90 7.83 525.58 525.03 C33 TO C31 529.23 528.48 525.01 524.27 148 12 0.50% 1.57 3.11 0.61 2.74 1.17 525.63 525.03 C34 TO C33 528.62 529.23 525.33 525.01 63 12 0.51% 0.77 2.53 0.41 2.76 1.99 525.76 525.76 � C35 TO C34 528.62 528.62 525.62 525.33 29 12 1.00% 0.42 2.73 0.26 3.87 3.45 525.90 525.87 C4 TO C2 526.10 523.05 515.44 515.03 161 30 0.25% 10.82 3.87 0.55 22.48 11.66 520.81 520.72 C5 TO C4 524.31 526.10 516.17 515.94 89 24 0.26% 3.07 2.75 0.38 12.49 9.41 520.98 520.97 C6 TO C5 524.31 524.31 520.31 517.17 25 12 12.56% 020 5.64 0.10 13.71 13.51 520.99 520.99 C7 TO C5 523.72 524.31 516.45 516.17 111 24 0.25% 2.63 2.59 0.35 12.34 9.71 521.00 520.99 C8 TO C7 523.72 523.72 519.72 517.45 26 12 8.73% 0.21 5.04 0.12 11.43 11.22 521.01 521.01 C9 TO C7 522.93 523.72 516.82 516.45 147 24 0.25% 2.08 2.41 0.31 12.33 10.24 521.02 521.01 Hugh G.Goldsmith Associates Inc. 99095HYD.xIs/C100-SBUH-REV SUB-BASIN B (MAY CREEK BASIN) 1 Sub-Basin B 25 year Backwater Analysis ID Rim Up Rim Dn IE Up IE Dn Len Diam Slope Qdes Vdes d/Diam Qfull Qexcess HGL Up HGL Dn ft ft ft ft ft in % cfs f s cfs cfs ft ft B1 TO POND 521.38 512.50 515.50 512.50 39.00 24 7.69% 9.51 12.68 0.29 68.14 58.63 520.27 520.21 610 TO 88 523.60 523.22 516.55 516.36 76.00 24 025% 8.09 3.64 0.67 12.28 4.19 521.24 521.16 811 TO 810 523.98 523.60 516.74 516.55 76.00 24 0.25% 7.83 3.61 0.66 12.28 4.45 521.53 521.45 B12 TO B11 523.98 523.98 520.98 517.74 27.00 12 12.00% 0.18 5.39 0.10 13.40 13.22 521.73 521.73 B13 TO 811 524.73 523.98 517.12 516.74 150.00 24 0.25% 7.33 3.55 0.63 12.37 5.04 521.86 521.73 B14 TO B13 524.73 524.73 521.73 518.12 27.00 12 13.37% 0.20 5.80 0.10 14.15 13.94 522.28 52228 B15 TO 613 525.47 524.73 519.78 517.62 120.00 18 1.80% 6.51 7.05 0.52 15.30 8.80 522.67 522.28 B16 TO B15 526.00 525.47 520.54 519.78 42.00 18 1.81°/ 6.05 6.91 0.50 15.34 9.29 523.01 522.89 B17 TO B16 526.25 526.00 521.18 520.54 35.00 18 1.83°/ 5.37 6.68 0.46 15.43 10.05 523.52 523.44 B18 TO 617 526.94 526.25 523.50 521.68 148.00 12 1.23°/ 1.26 3.98 0.42 4.29 3.03 523.94 523.70 619 TO B18 526.94 526.94 523.94 523.50 29.00 12 1.52% 0.44 3.24 0.25 4.77 4.33 524.20 523.94 j 82 TO B 1 521.38 521.38 518.38 516.50 29.00 12 6.48% 0.08 3.24 0.08 9.85 9.77 520.32 520.32 B20 TO 817 526.59 526.25 521.86 521.18 68.00 18 1.00% 3.37 4.72 0.42 11.41 8.03 523.76 523.70 B21 TO 620 526.86 526.56 522.71 522.36 35.00 12 1.00% 3.35 4.96 0.80 3.87 0.52 524.16 523.90 622 TO B21 526.86 526.86 523.86 522.71 27.00 12 4.26% 0.15 3.53 0.12 7.98 7.83 524.46 524.46 623 TO B21 527.48 526.86 523.92 522.71 121.00 12 1.00% 3.13 4.87 0.76 3.87 0.74 525.25 524.46 B24 TO 823 527.48 527.48 524.48 523.92 29.00 12 1.93°/a 1.51 4.94 0.41 5.38 3.86 525.55 525.51 B25 TO 624 528.30 527.48 525.30 524.48 41.00 12 2.00% 0.76 4.06 0.29 5.47 4.71 525.77 525.76 B26 TO B23 528.02 527.48 524.28 523.92 43.00 12 0.84% 1.49 3.66 0.51 3.54 2.05 525.57 525.51 I B27 TO B26 528.19 528.02 524.90 52428 74.00 12 0.84% 1.53 3.68 0.52 3.54 2.01 525.85 525.73 B28 TO B27 528.19 528.19 525.19 524.90 29.00 12 1.00% 0.77 3.17 0.34 3.87 3.10 525.85 525.85 B29 TO 61 520.65 521.38 517.36 516.50 147.00 12 0.59% 0.65 2.51 0.36 2.96 2.31 520.36 520.32 63 TO B1 521.71 521.38 515.65 515.50 58.00 24 0.26% 8.85 3.78 0.70 12.49 3.64 520.39 520.32 B30 TO B29 520.65 520.65 517.65 517.36 29.00 12 1.00% 0.25 2.40 0.21 3.87 3.62 520.42 520.41 B4 TO B3 521.71 521.71 518.71 516.65 29.00 12 7.10% 0.20 4.60 0.12 10.31 10.11 520.46 520.46 B5 TO B3 522.09 521.71 515.82 515.65 69.00 24 0.25% 8.66 3.70 0.70 12.20 3.53 520.55 520.46 B6 TO B5 522.46 522.09 515.99 515.82 69.00 24 0.25% 8.69 3.70 0.71 12.20 3.51 520.68 520.59 B7 TO B6 522.46 522.46 519.46 516.99 27.00 12 9.15% 0.18 4.86 0.11 11.70 11.52 520.71 520.71 B8 TO B6 523.22 522.46 516.36 515.99 147.00 24 0.25% 8.87 3.75 0.71 12.33 3.46 520.90 520.71 B9 TO B8 523.22 523.22 520.22 517.36 27.00 12 10.59% 0.18 5.14 0.10 12.59 12.41 521.16 521.16 Hugh G.Goldsmith Associates Inc. 99095HYD.xIs/825 REV Sub-Basin B 100 year Backwater Analysis ID Rim Up Rim Dn IE Up IE Dn Len Diam Slope Qdes Vdes d/Diam Qfull Qexcess HGL Up HGL Dn ft ft ft ft ft in % cfs f s cfs cfs ft ft B19 TO B18 526.94 526.94 523.94 523.50 29.00 12 1.52% 0.49 3.33 0.26 4.46 3.96 525.06 525.06 618 TO B17 526.94 526.25 523.50 521.68 148.00 12 123% 1.43 4.13 0.45 4.01 2.58 525.06 524.85 B28 TO B27 528.19 528.19 525.19 524.90 29.00 12 1.00% 0.87 3.30 0.36 3.62 2.75 527.56 527.54 B27 TO B26 528.19 528.02 524.90 524.28 74.00 12 0.84% 1.73 3.83 0.56 3.31 1.58 527.54 527.39 826 TO 823 528.02 527.48 524.28 523.92 43.00 12 0.84% 1.70 3.80 0.55 3.31 1.61 527.20 527.11 B14 TO B13 524.73 524.73 521.73 518.12 27.00 12 13.37% 0.23 5.98 0.11 13.23 13.00 523.11 523.11 612 TO B11 523.98 523.98 520.98 517.74 27.00 12 12.00% 0.20 5.56 0.11 12.53 12.33 522.44 522.44 89 TO BS 523.22 523.22 520.22 517.36 27.00 12 10.59% 020 5.30 0.11 11.77 11.57 521.75 521.75 87 TO 66 522.46 522.46 519.46 516.99 27.00 12 9.15% 0.20 5.02 0.11 10.94 10.74 52120 52120 B4 TO 63 521.71 521.71 518.71 516.65 29.00 12 7.10% 0.23 4.78 0.13 9.64 9.41 520.89 520.88 B2 TO B 1 521.38 521.38 518.38 516.50 29.00 12 6.48% 0.09 3.40 0.08 9.21 9.12 520.71 520.71 622 TO B21 526.86 526.86 523.86 522.71 27.00 12 4.26% 0.17 3.67 0.12 7.46 7.29 525.79 525.79 B25 TO B24 528.30 527.48 525.30 524.48 41.00 12 2.00% 0.86 4.19 0.30 5.12 4.26 527.43 527.41 B24 TO B23 527.48 527.48 524.48 523.92 29.00 12 1.93°/ 1.72 5.11 0.44 5.03 3.31 527.17 527.11 B23 TO B21 527.48 526.86 523.92 522.71 121.00 12 1.00% 3.56 5.03 0.84 3.62 0.06 526.81 525.79 821 TO 820 526.86 526.56 522.71 522.36 35.00 12 1.00% 3.81 5.11 0.90 3.62 -0.20 525.44 525.10 B20 TO 617 526.59 526.25 521.86 521.18 68.00 18 1.00% 3.85 4.90 0.45 10.67 6.82 524.93 524.85 B17 TO 816 526.25 526.00 521.18 520.54 35.00 18 1.83% 6.12 6.96 0.50 14.42 8.30 524.65 524.55 616 TO B15 526.00 525.47 520.54 519.78 42.00 18 1.81% 6.89 7.18 0.53 14.35 7.46 524.03 523.88 815 TO B13 525.47 524.73 519.78 517.62 120.00 18 1.80% 7.41 7.33 0.55 14.31 6.90 523.62 523.11 813 TO 811 524.73 523.98 517.12 516.74 150.00 24 0.25% 8.34 3.69 0.68 11.56 3.22 522.61 522.44 B 11 TO 810 523.98 523.60 516.74 516.55 76.00 24 0.25% 8.92 3.75 0.71 11.49 2.56 522.21 522.11 B10 TO BS 523.60 523.22 516.55 516.36 76.00 24 0.25% 9.22 3.78 0.73 11.49 2.27 521.86 521.75 B8 TO B6 523.22 522.46 516.36 515.99 147.00 24 0.25% 10.09 3.89 0.77 11.52 1.43 521.45 521.20 86 TO B5 522.46 522.09 515.99 515.82 69.00 24 0.25% 9.89 3.84 0.77 11.40 1.51 521.16 521.05 BS TO B3 522.09 521.71 515.82 515.65 69.00 24 0.25°/ 9.88 3.84 0.77 11.40 1.53 521.00 520.88 63 TO 81 521.71 521.38 515.65 515.50 58.00 24 0.26% 10.09 3.93 0.76 11.68 1.59 520.80 520.71 B30 TO B29 520.65 520.65 517.65 517.36 29.00 12 1.00% 0.29 2.48 0.22 3.62 3.33 520.65 520.65 829 TO B1 520.65 521.38 517.36 516.50 147.00 12 0.59% 0.74 2.62 0.39 2.77 2.02 520.76 520.71 61 TO POND 521.38 512.50 515.50 512.50 39.00 24 7.69% 10.83 13.10 0.30 63.71 52.88 520.65 520.57 Hugh G.Goldsmith Associates Inc. 99095HYD.xIs/B100 REV SUB-BASIN D ; (CEDAR RIVER BASIN) Sub-Basin D 25 year Backwater Analysis ID Rim Up Rim Dn IE Up IE Dn Len Diam Slope Qdes Vdes d/Diam Qfull Qexcess HGL Up HGL Dn ft ft ft ft ft in % cfs f s cfs cfs ft ft D-10 TO D-9 520.95 520.95 517.75 517.46 29.00 12 1.00% 0.42 2.73 0.26 3.62 320 518.69 518.69 D-9 TO D-7 520.95 520.38 517.46 516.92 108.00 12 0.50% 0.82 2.56 0.43 2.56 1.74 518.61 518.56 D-8 TO D-7 520.38 520.38 517.21 516.92 29.00 12 1.00% 0.73 3.12 0.33 3.62 2.89 518.57 518.56 D-7 TO D-5 520.38 519.83 516.92 516.38 108.00 12 0.50% 2.25 3.46 0.77 2.56 0.31 518.44 518.08 D-6 TO D-5 519.83 519.83 516.67 516.38 29.00 12 1.00% 0.68 3.05 0.32 3.62 2.94 518.09 518.08 D-5 TO D-4 519.83 520.09 515.88 515.49 78.00 18 0.50% 3.38 3.70 0.51 7.54 4.16 517.96 517.89 D-4 TO D-2 520.09 524.45 515.49 514.86 126.00 18 0.50% 3.38 3.70 0.51 7.54 4.16 517.70 517.59 D-3 TO D-2 524.45 524.45 521.45 515.36 27.00 12 22.56% 0.15 6.23 0.08 17.18 17.03 521.55 517.59 D-2 TO D-1 524.45 521.40 514.86 514.22 128.00 18 0.50% 3.68 3.79 0.54 7.54 3.86 517.38 517.25 D-1 TO POND 521.40 517.00 514.22 508.50 75.00 18 7.63% 4.18 10.30 028 29.45 25.27 517.10 517.00 Hugh G.Goldsmith Assoclates Inc. 99095HYD.xIs/D25 REV Sub-Basin D 100 year Backwater Analysis ID Rim Up Rim Dn IE Up IE Dn Len Diam Slope Qdes Vdes d/Diam Qfull Qexcess HGL Up HGL Dn ft ft ft ft ft in % cfs f s cfs cfs ft ft D-10 TO D-9 520.95 520.95 517.75 517.46 29.00 12 1.00% 0.48 2.80 027 3.87 3.39 519.08 519.08 D-9 TO D-7 520.95 520.38 517.46 516.92 108.00 12 0.50% 0.93 2.65 0.46 2.74 1.80 518.99 51$.92 D-8 TO D-7 520.38 520.38 51721 516.92 29.00 12 1.00% 0.83 3.25 0.35 3.87 3.04 518.94 518.92 I D-7 TO D-5 520.38 519.83 516.92 516.38 108.00 12 0.50% 2.55 3.57 0.85 2.74 0.18 518.79 518.32 � D-6 TO D-5 519.83 519.83 516.67 516.38 29.00 12 1.00% 0.77 3.17 0.34 3.87 3.10 518.33 518.32 D-5 TO D-4 519.83 520.09 515.88 515.49 78.00 18 0.50% 3.84 3.84 0.55 8.07 4.23 518.17 518.09 D-4 TO D-2 520.09 524.45 515.49 514.86 126.00 18 0.50% 3.84 3.84 0.55 8.07 4.23 517.86 517.72 D-3 TO D-2 524.45 524.45 521.45 515.36 27.00 12 22.56% 0.17 6.50 0.09 18.37 18.20 521.55 517.72 I D-2 TO D-1 524.45 521.40 514.86 514.22 128.00 18 0.50% 4.18 3.95 0.58 8.07 3.88 517.47 517.30 D-1 TO POND 521.40 517.00 514.22 508.50 75.00 18 7.63% 4.74 10.62 0.30 31.50 26.76 517.13 517.00 Hugh G.Goldsmith Associates Inc. 99095HYD.xIs/D100 REV SUB-BASIN E (CEDAR RIVER BASIN) Sub-Basin E 25 year Backwater Analysis ID Rim Up Rim Dn IE Up IE Dn Len Diam Slope �des Vdes d/Diam �full Qexcess HGL Up HGL Dn ft ft ft ft ft in % cfs f s cfs cfs ft ft E•5 TO E-4 520.46 520.46 517.00 516.47 53.00 12 1.00% 0.76 3.16 0.34 3.87 3.11 517.94 517.82 E-4 TO E-2 520.46 521.20 516.47 516.25 45.00 12 0.49% 1.49 3.04 0.60 2.71 1.21 517.82 517.75 E-3 TO E-2 524.10 521.20 518.98 516.25 182.00 12 1.50% 0,40 3.15 0.24 4.74 4.33 519.22 517.75 E-2 TO E-1 521.20 518.50 516.25 514.03 148.00 12 1.50% 1.85 4.79 0.49 4.74 2.89 517.64 517.30 F-1 TO POND 518.50 517.00 514.03 509.00 64.00 12 7.86% 2.2A 9.05 0.35 10.85 8.57 516.92 516.70 Hugh G.Goldsmith Associates Inc. 99095HYD.xIs/E25 Sub-Basin E 100 year Backwater Analysis ID Rim Up Rim Dn IE Up IE Dn Len Diam Slope Qdes Vdes d/Diam �full Qexcess HGL Up HGL Dn ft ft ft ft ft in % cfs f s cfs cfs ft ft E-5 TO E-4 520.46 � 520.46 517.00 516.47 53.00 12 1.00% 0.86 3.29 0.36 3.87 3.01 518.41 518.38 E-4 TO E-2 520.46 521.20 516.47 516.25 45.00 12 0.49% 1.70 3.16 0.65 2.71 1.01 518.38 518.30 E-3 TO E-2 524.10 521.20 518.98 516.25 182.00 12 1.50% 0.46 3.27 0.25 4.74 4.28 519.24 518.30 E-2 TO E-1 521.20 518.50 516.25 514.03 148.00 12 1.50% 2.10 4,97 0.53 4.74 2.64 518.16 517.73 F-1 TO POND 518.50 517.00 514.03 509.00 64.00 12 7.86% 2.58 9.45 0.38 10.85 8.26 517.29 517.00 Hugh G.Goldsmith Associates Inc. 99095HYD.xIs/E100 � Verification of Spill Control Catch Basins All spill control manholes are designed to use a frop tee control structure with a diameter equal to the diameter of the downstream pipe. The top of riser is set at one foot above the crown of the downstream pipe. This ensures that a balance is maintained between conveyance capacity during large events and providing spill control during normal operations. I Overflows Equations: Q = C(L - 0.2H)H3'2 C = 3.27 + 0.4 H/P � CB# B-1 Q,� = 10.40 cfs Ha,vni�. = 2.85 ft. ' P = 3.0 ft. L = 6.28 ft. (24 in. Riser) C = 3.27 + 0.4 (2.85/3.0) , C = 3.65 I Q = 3.65 (6.28 - 0.2(2.85)) (2.85)3'2 il Q = 100.33 cfs > 10.40 cfs .�. OK , � itJyUy�-1.33j (iuld�mrth & A�soaatC�. Inc. iechiuc�;l l��Jr,rmcitrmi Report Jnr rite/'tcu n),ilc.urrrri N��;ir,'�u!:. CB# C-1 Q,� = 16.29cfs Havai�. = 4.50 ft. P = 3.5ft. L = 7.85 ft. (30 in. Riser) C = 3.27 + 0.4 (4.5/3.5) C = 3.78 Q = 3.78 (7.85 - 0.2(4.5)) (4.5)3'z Q = 251.21 cfs > 16.29 cfs .-. OK CB# D-1 Q,� = 4.50cfs HAvai�. = 4.68 ft. P = 2.5 ft. L = 4.71 ft. (18 in. Riser) C = 3.27 + 0.4 (4.68/2.5) C = 4.02 Q = 4.02 (4.71 - 0.2(4.68)) (4.68)� Q = 153.65 cfs > 4.50 cfs .•. OK CB# E-1 Q,00 = 2•60 cfs H,avAi�. = 2•47 ft. P = 2ft. L = 3.14 ft. (12 in. Riser) C = 3.27 + 0.4 (2.47/2) C = 3.76 Q = 3.76 (3.14 - 0.2(2.47)) (2.47)� Q = 38.69 cfs > 2.60 cfs .•. OK �� s-2s ' r99095-1335 Goldsmith&Associates,Inc. Technical Infi�rmatrnn Reporr for the Plat of Maureen Highlands i 6. Special Reports and Studies The following reports and studies were reviewed for the Maureen Highland project. •' Level 3 Downstream Analysis and Drainage Control PIaNReport for the Preliminary Plat of Maureen Highlands. Dated: May 2001, Hugh G. Goldsmith & Associates, Inc. •' Adopted May Creek Basin Action Plan (April 2001) •' Draft Dickson Drainage Investigation, Volume 1. Dated: December 1992, R. C. Beck & Associates •' Windwood Technical Information Report Revised June 11 1999, Triad Associates •' Maureen Highlands Traffic Impact Analysis Dated: May 22, 2002 Transportation, Planning & Engineering, Inc. •' GeoTechnical Report, Proposed Maureen Highlands Subdivision Dated: May 24, 2001, GeoEngineers, Inc. •' Maureen Highlands Sensitive Areas and Mitigation Report Dated: February 20, 2002 Talasaea Consultants, Inc. = Maureen Highlands Wetland Mitigation Report Dated February 20, 2002 Talasaea Consultants, Inc. •32 Plat of Maureen Highlands Technical Information Report (T.I.R.) Dated: March 2002, Revised June 2002 Hugh G. Goldsmith 8� Associates, Inc. ' Previously Submitted 2 Submitted March 2002 3 With this submittal 5-11 R99095-1340 Goldsmith&Associates Technical Information Report for the Plat of Maureen Highlands 7. Other Permits • City of Renton Demolition Permit • Building Permits Washinqton State Department of Ecoloqv • NPDES Stormwater Permit 8. ECS Analysis and Design The erosion/sedimentation control for the site will be provided by a series of check dams, gravel filter dikes, cut-off trenches and stabilized construction entrances as shown on Sheets 3-1 to 3-7 of the plans. Additionally, the two permanent detention / retention facilities located in both Tract "A" (Cedar River Basin) and Tract "C" (May Creek Basin) will be used as part of the temporary sediment pond for the entire site. These facilities will be constructed per the Final September 1998, King County, Washington, Surface Water Design Manual criteria. The calculations for the required sediment pond sizing is in accordance with Section D.4.5.1 and D.4.5.2 of Appendix D of the Final September 1998, King County, Washington, Surface Water Design Manual. The permanent control structures for the detention facilities and the permanent overflow flow structures from the detention facilities shall be constructed as part of the TESC plan. A recommended construction sequence is located on Sheet 3-6 of the plans. To provide a more conservative design, the developed 10-year storm event release rate is held at the existing condition 2-year runoff rate. The following represents the runoff and design calculations for the proposed facilities including level pool routing and overflow design calculations. 8-1 R99095-]340 Goldsmith& Associates Technicci!InJorrriatiori Repart/i�r the Pla�nf Ma�ireen Hixhlurids Temporarv Sediment Cedar River Basin Developed Area: A = 10.20 Ac. (CN = 91) Existing Area A = 4.86 Ac. (CN = 85) Control Standard: 10-Yr./24-Hr. developed held at 2-Yr./24-Hr. existing rate 24 year Rainfall = 2.0 in. 10 year Rainfall = 2.9 in. Inflow (10-Yr./24-Hr. Developed): Q2D = 4.61 cfs (2-Yr./24-Hr. Existing): G22E = 0.57 cfs Pond Details: Orifice Diameter = 3.0 in. QouT = 0.53 cfs 10-Yr. Developed WS = 515.65 ft. Required Detention Volume = 41818 cf Emergency Overflow Bird Cage: Q,000 = 6.91 cfs Manhold Diameter = 48" HREdUIRED = O..3Z Rim Elev. = 517.50 Emergency Overflow W-S = 517.82 Pond Summary: Top Dike: Elevation: 518.5 Width: 6' Emergency Overflow Birdcage: Elevation: 517.50 Diameter: 48" Pond Bottom: Elevation: 511.0 Orifice Diameter: 3.0 in. Detention Volume Required: 41,818 C.F. Detention Volume Designed: 59,242 C.F. @ Elev. = 517.0 (42% F.S.) 10-year Water Surface = 515.65 a-2 R99095-1.340 Goldsmith& Associates Technica!Information Report for the Plat ojMauree�z Highlands EX-CED Event Summary: BasinlD Peak Q Peak T Peak Vol Area Method Raintype Event ------ (cfs) (hrs) (ac-ft) ac /Loss EX-CED 0.57 8.00 0.3220 4.86 SBUH/SCS kc24hr 2 yr Drainage Area: EX-CED Hyd Method: SBUH Hyd Loss Method: SCS CN Number Peak Factor: 484.00 SCS Abs: 0.20 Storm Dur: 24.00 hrs Intv: 10.00 min Area CN TC Pervious 4.8600 ac 85.00 0.46 hrs Impervious 0.0000 ac 0.00 0.00 hrs Total 4.8600 ac Supporting Data: Pervious CN Data: EXISTING SITE 85.00 4.8600 ac Pervious TC Data: Flow type: Description: Length: Slope: Coeff: Travel Time Sheet None Entered 300.00 ft 2.00% 0.1300 26.62 min Shallow None Entered 100.00 ft 2.00% 11.0000 1.07 min TESC-CED Event Summary: BasinlD Peak Q Peak T Peak Vol Area Method Raintype Event ------- (cfs) (hrs) (ac-ft) ac /Loss TESC-CED 4.61 8.00 1.6814 10.20 SBUH/SCS kc24hr 10 yr TESC-CED 6.91 8.00 2.4834 1020 SBUH/SCS kc24hr 100 yr Drainage Area: TESC-CED Hyd Method: SBUH Hyd Loss Method: SCS CN Number Peak Factor: 484.00 SCS Abs: 020 Storm Dur: 24.00 hrs intv: 10.00 min Area CN TC Pervious 10.2000 ac 91.00 0.28 hrs I� Impervious 0.0000 ac 0.00 0.00 hrs ' Total 10.2000 ac Supporting Data: Pervious CN Data: cleared site 91.00 10.2000 ac Pervious TC Data: Flow type: Description: Length: Slope: Coeff: Travel Time Channel Prototype tc just to have something 900.00 ft 0.50% 15.0000 14.14 min Sheet Prototype tc just to have something 100.00 ft 0.50% 0.0110 2.67 min � Control Structure ID: CED-OUT - Multiple Orifice Structure ' Descrip: TESC CONTROL ORIFICE Start EI Max EI Increment 511.0000 ft 517.0000 ft 0.10 Orif Coeff: 0.62 Bottom EI: 0.00 ft � I Lowest Diam: 3.0000 in Node ID: CED-PND Desc: CEDAR R�VER TESC POND Start EI: 506.0000 ft Max EI: 517.0000 ft Contrib Basin: Contrib Hyd: Stage Area Volume Volume , 506.00 1002.00 0.00 cf 0.0000 acft 507.00 1549.00 1275.50 cf 0.0293 acft 508.00 2679.00 3389.50 cf 0.0778 acft 510.00 4623.00 10691.50 cf 0.2454 acft I i 8-3 R99095-L340 Goldsmith&Associa[es Teclrnicul/nforn:utron Report for the Plut af Muureex HrKhlunds i I 511.00 5781.00 15893.50 cf 0.3649 acft 512.00 7030.00 22299.00 cf 0.5119 acft 514.00 9742.00 39071.00 cf 0.8969 acft 516.00 12756.00 61569.00 cf 1.4134 acft 517.00 14378.00 75136.00 cf 1.7249 acft RLPCOMPUTE[N-001]SUMMARY 10 yr Match Q:0.5700 cfs Peak Out Q:0.5269 cfs- Peak Stg: 515.65 ft-Active Vol:0.96 acft I i � I 8-4 I R99095-1340 Goldsmith&Associates Technical Information Report for the Plat qf Muureen Highlands Temporarv Sediment Mav Creek Basin Developed Area: A = 27.85 Ac. (CN = 91) Existing Area A = 34.23 Ac. (CN = 85) Control Standard: 10-Yr./24-Hr. developed held at 2-Yr./24-Hr. existing rate 24 year Rainfall = 2.0 in. 10 year Rainfall = 2.9 in. Inflow (10-Yr./24-Hr. Developed): Q2D = 14.02 cfs (2-Yr./24-Hr. Existing): Q2E = 5.06 cfs Pond Details: Orifice Diameter = 6.0 in. Qour = 5.06 cfs 10-Yr. Developed WS = 517.11 ft. Required Detention Volume = 129,373 cf Emergency Overflow Birdcage: Q,�p = 20.95 cfs Manhold Diameter = 96" HREQUIRED = O.4Z Rim Elev. = 521.0 Emergency Overflow W.S. = 521.42 Pond Summary: Top Dike: Elevation: 522.0 Width: 50' Emergency Overflow Birdcage: Elevation: 521.0 Diameter: 96" Pond Bottom: Elevation: 515.5 Orifice Diameter: 6.0 in. Detention Volume Required: 129,373 C.F. Detention Volume Designed: 380,714 C.F. 10-year Water Surface = 517.11 . I ' , ', ��..� �' �' 8-5 R99095-1.340 Goldsmith&Associates Technical Informatron Report jor the Plar of Maureen Nighlands CLEARHIS EX-MAY Event Summary: BasinlD Peak Q Peak T Peak Vol Area Method Raintype Event ------- (cfs) (hrs) (ac-ft) ac /Loss EX-MAY 5.06 8.00 2.2679 3423 SBUH/SCS kc24hr 2 yr Drainage Area: EX-MAY Hyd Method: SBUH Hyd Loss Method: SCS CN Number Peak Factor: 484.00 SCS Abs: 0.20 Storm Dur: 24.00 hrs Intv: 10.00 min Area CN TC Pervious 34.2300 ac 85.00 0.27 hrs Impervious 0.0000 ac 0.00 0.00 hrs Total 34.2300 ac Supporting Data: Pervious CN Data: EXISTING SITE 85.00 34.2300 ac Pervious TC Data: Flow type: Description: Length: Slope: Coeff: Travel Time Sheet None Entered 100.00 ft 1.30% 0.1300 13.13 min Channel None Entered 500.00 ft 2.00% 20.0000 2.95 min TESC-MAY Event Summary: BasinlD Peak Q Peak T Peak Vol Area Method Raintype Event ------- (cfs) (hrs) (ac-ft) ac lLoss TESC-MAY 14.02 8.00 4.5908 27.85 SBUH/SCS kc24hr 10 yr TESC-MAY 20.95 8.00 6.7806 27.85 SBUH/SCS kc24hr 100 yr Drainage Area: TESC-MAY Hyd Method: SBUH Hyd Loss Method: SCS CN Number Peak Factor: 484.00 SCS Abs: 0.20 Storm Dur: 24.00 hrs Intv: 10.00 min Area CN TC Pervious 27.8500 ac 91.00 0.18 hrs Impervious 0.0000 ac 0.00 0.00 hrs Total 27.8500 ac Supporting Data: Pervious CN Data: cleared site 91.00 27.8500 ac Pervious TC Data: Flow type: Description: Length: Slope: Coeff: Travel Time Channel None Entered 500.00 ft 0.50% 15.0000 7.86 min Sheet None Entered 100.00 ft 0.50°0 0.0110 2.67 min Control Structure ID: MAY-OUT - Multiple Orifice Structure Descrip: TESC CONTROL ORIFICE Start EI Max EI Increment 515.5000 ft 520.5000 ft 0.10 Orif Coeff: 0.62 Bottom EI: 0.00 ft Lowest Diam: 6.0000 in Node ID: MAY-POND Desc: MAY CREEK TESC POND Start EI: 515.5000 ft Max EI: 520.5000 ft Contrib Basin: Contrib Hyd: Stage Area Volume Volume 8-6 R9909�-1.340 Goldsmith & Associa[es Tech�:icu!/�tforntntinn Report fnr the Plar oJMuureen HiKhlunds 510.00 60259.00 0.00 cf 0.0000 acft 512.00 65979.00 126238.00 cf 2.8980 acft 514.00 71909.00 264126.00 cf 6.0635 acft 515.50 76206.00 375212.25 cf 8.6137 acft 516.00 78001.00 413764.00 cf 9.4987 acft , 518.00 85329.00 577094.00 cf 13.2483 acft 520.00 90089.00 752512.00 cf 17.2753 acft 520.50 91282.00 797854.75 cf 18.3162 acft RLPCOMPUTE [N-002] SUMMARY 10 yr Match Q:5.0600 cfs Peak Out Q: 12404 cfs- Peak Stg:517.11 ft-Active Vol:2.97 acft 9. Bond Quantities, Facility Summaries, and Declaration of Covenant Construction Cost Estimate will be provided at time of Permit Application to determine bond amount. 1tJyUy�-131U Gold>n�i[h� Asso��a[es lerit�ttw(b;/<irmuuun t�epor7Jor tlte Ylc�1 uj Mciureen Higl�(cuids KING COUNTY,WASHINGTON. SURFACE WATER DESIGN MANUAL STORMWATER FACILITY SUMMARY SHEET Development Maureen HiQhlands Date 3/15/02 Location Portion of the East half of Section I1, Township 23 North, RanQe 5 East, W.M., City of Renton. WA. ENGINEER DEVELOPER Name Mark Barber Name J. Gordon Morrison Firm Hugh G. Goldsmith & Associates, Inc. Firm Wilshire Investments, Inc. Address P. O. Box 3565 Address 1285 - 140th Place N.E. Bellevue, WA. 98009 Bellevue, WA. 98007 Phone 425-462-1080 Phone 425-401-6463 Developed Site: Acres 38.52 Number of lots 124 + 1 Pazcel Number of detention facilities on site: Number of infiltration facilities on site: 2 ponds ponds vaults vaults tanks tanks Flow control provided in regional facility (give location) No flow control required Exemption number Downstream Drainage Basins Immediate Major Basin Basin A Cedar River Basin B May Creek Basin C Basin D Number & type of water quality facilities on site: biofiltration swale (regular/wet/ or sand filter (basic or large?) continuous inflow?) sand filter, linear (basic or lazge?) 2-Basic combined detention/WQ pond sand filter vault (basic or large?) (WQ portion basic or large?) combined detention/wetvault stormwater wetland compost filter wetpond (basic or large?) � filter strip wetvault flow dispersion farm management plan landscape management plan oil/water sepazator (baffle or coalescing plate?) catch basin inserts: Manufacturer pre-settling pond pre-settling structure: Manufacturer flow-splitter catchbasin DESIGN INFORMATION INDIVIDUAL BASIN A B C D Water Quality design flow 0.37 ac.-ft. 8.61 ac.-ft. Water Quality treated volume or ��•etpond �'r 3.1 10.8 9-2 R9y09i-].i40 Goldsmi[h & Associates 7�erir�uccil ht%or�riatrnn Repurt%orlhe Plat uf,'lluureen Hi,�hl�u�ds KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL DESIGN TOTAL INDIVIDUAL BASIN INFORMATION, cont'd Drainage basin(s) A B C D Onsite area 4.58 Ac. 33.47 Ac. Offsite area 0 Ac. 3.3 Ac. Type of Storage Facility Pond Pond Live Storage Volume 1.36 ac.-ft. 8.61 ac.-ft. Predeveloped Runoff Rate 2-year 0.19 cfs 0.94 cfs 10-year 0.32 cfs 1.64 cfs 100-yeaz 0.54 cfs 2.82 cfs Developed runoff rate 2-year 0.10 cfs 0.60 cfs 10-year 0.28 cfs 1.64 cfs 100-year 1.16 cfs 3.93 cfs Type of restrictor Orifice Orifice Size of orifice/restriction No. 1 1.25 in. @ 509.0 325 in. @ 513.50 No. 2 1.90 in. @ 514.9 5.00 in. @ 51825 No. 3 1.75 in. @ 515.60 4.00 in. @ 518.90 No. 4 FLOW CONTROL & WATER QUALITY FACILITY SUMMARY SHEET SKETCH All detention, infiltration and water quality facilities must include a sketch per the following criteria: l. Heading for the drawings should be located at the top of the sketch (top nght-hand corner). The heading shouid contain: • North arrow (point up or to left) • D9# • Plat name or short plat number • Address (nearest) • Date drawn (or updated) • lfiomas Brothers page, grid number 2. Label CBs and MHs with the plan and profile designation. Label the control structure in writing or � abbreviate with C.S. Indicate which structures provide spill control. Pipes-- indicate: Pipe size Pipe length I Flow direction � Use s singie heavyweight line 4. Tanks-- use a double, heavyweight line and indicate size (diameter) , 5. Access roads �I • Outline the limits of the road � • Fill the outline with dots if the road is gravel. Label in writing if another surface. 6. Other Standard Symbols: I • Bollards: • • • • ■ ■ ■ ■ • Rip rap o00000 000000 • Fences: --x---x---x---x---x---x--- ' • Ditches -D----•D-----�D------�D I 7. Label trash racks in writing. � 8. Label all streets with the actual street sign designation. If you don't know the actual street name, consult the plat map. 9. Include easements and lot lines or tract limits when possible. , l0. Arran�e all the labeling or wnting to read from left to right or from bottom to top with reference to a properly oriented heading. 11. Indicate driveways or features that may impact access, maintenance or replacement. 9-3 R99095-1.340 Goldsmith&Associates Teci:nica!Injormation Report fi�r rhe Plat of Maureen Highlands KING COL\TY, WASH[NGTON, SURFACE WATER DESIGN MANUAL 10. Operations and Maintenance Manual 10-1 R99095-].330 Goldsmith R Associates Teclnurul InJ��ririutinn Re/�ort jor the Ylut nf Mm�reen Hi�hl�tnds KING COUNTY, «'ASHINGTON, SURFACE WATER DESIGN MANUAL MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES NO. 1 - DETENTION PONDS Maintenance Conditions When Maintenance Results Expected When Component Defect Is Needed Maintenance Is Performed General Trash&Debris Any trash and debris which exceed 1 cubic foot Trash and debris cleared from site. per 1,000 square feet(this is about equal to the amount of trash it would take to fill up one standard size office garbage can). In general, there should be no visual evidence of dumping. Poisonous Any poisonous or nuisance vegetation which may No danger of poisonous vegetation Vegetation constitute a hazard to County personnel or the where County personnel or the public. public might normally be. (Coordination with Seattle-King County Health Department) Poilution Oil,gasoline,or other contaminants of one No contaminants present other than gallon or more or any amount found that could: a surface film. (Coordination with 1)cause damage to plant, animal,or marine life; Seattle/King County Health 2)constitute a fire hazard;or 3)be flushed Department) downstream during rain storms. Unmowed Grass/ If facility is located in private residential area, When mowing is needed, Ground Cover mowing is needed when grass exceeds 18 grass/ground cover should be inches in height. In other areas,the general mowed to 2 inches in height. policy is to make the pond site match adjacent Mowing of selected higher use ground cover and terrain as long as there is no areas rather than the entire slope interference with the function of the facility. may be acceptabie for some situations. Rodent Holes Any evidence of rodent holes if facility is acting Rodents destroyed and dam or as a dam or berm, or any evidence of water berm repaired. (Coordination with piping through dam or berm via rodent holes. Seattle/King County Health Department) Insects When insects such as wasps and hornets insects destroyed or removed from interfere with maintenance activities. site. Tree Growth Tree growth does not allow maintenance access Trees do not hinder maintenance or interferes with maintenance activity(i.e., siope activities. Selectively cultivate trees mowing,silt removal,vactoring,or equipment such as alders for firewood. movements). If trees are not interfering with access,leave trees alone. Side Slopes of Pond Erosion Eroded damage over 2 inches deep where Slopes should be stabilized by cause of damage is still present or where there using appropriate erosion control is potential for continued erosion. measure(s); e.g., rock reinforcement, planting of grass, compaction. Storage Area Sediment Accumulated sediment that exceeds 10%of the Sediment cleaned out to designed designed pond depth. pond shape and depth; pond reseeded if necessary to control erosion. Pond Dikes Settlements Any part of dike which has settled 4 inches lower Dike should be built back to the than the design elevation. design elevation. Emergency Rock Missing Only one layer of rock exists above native soil in Replace rocks to design standards. Overflow/Spillway area five square feet or larger, or any exposure of native soil at the top of out flow path of spillway. Rip-rap on inside slopes need not be replaced. K4�)fjyi-].;-lU Guldtiini[h �� Associcitcti 7�F�rhitir<tl L�/arnt�rtrr+n Repur!Inr Ihr Plu1 u),Llcrurnen Hi,�ltl«rtds 1G2 APPENDIX A MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES NO. 2 - INFILTRATION Maintenance Conditions When Maintenance Results Expected When Component Defect Is Needed Maintenance Is Performed General Trash& Debris See"Ponds" Standard No. 1 See"Ponds" Standard No. 1 Poisonous Vegetation See"Ponds"Standard No. 1 See`Ponds"Standard No. 1 Pollution See"Ponds"Standard No. 1 See"Ponds"Standarcl No. 1 Unmowed Grass/ See°Ponds"Standard No. 1 See"Ponds"Standard No. 1 Ground Cover Rodent Holes See"Ponds"Standard No. 1 See"Ponds"Standard No. 1 Insects See°Ponds"Standard No. 1 See"Ponds"Standard No. 1 Storage Area Sediment A percolation test pit or test of facility indicates Sediment is removed and/or facility facility is only working at 90% of its designed is cleaned so that infiltration system capabilities. If two inches or more sediment is worics according to design. present, remove. Sheet Cover(If Sheet cover is visible and has more than three Sheet cover repaired or replaced. Applicable) 1/4-inch holes in it. Sump Filled with Any sediment and debris filling vautt to 10%of Clean out sump to design depth. Sediment and Debris depth from sump bottom to bottom of outlet pipe (If Applicable) or obstructing flow into the connector pipe. Filter Bags Filled with Sediment Sediment and debris fill bag more than 1/2 full. Replace filter bag or redesign and Debris system. Rock Fitters Sediment and Debris By visual inspection, little or no water flows Replace gravei in rock filter. through tilter during heavy rain storms. Side Slopes of Pond Erosion See"Ponds"Standard No. 1 See `Ponds" Standard No. 1 Emergency Rock Missing See`Ponds"Standard No. 1 Overflow Spillway Settling Ponds and Sediment Remove when 6"or more. Vaults Note: Sediment accumulation of more than 25 inches per year may indicate excessive erosion is occurring upstream of the facility or that conveyance systems are not being properly maintained. The contributing drainage area should be checked for erosion problems or inadequate maintenance of conveyance systems if excessive sedimentation is noted in an infiltration facility. Check twice a year during first 2 years of operation; once a year thereafter. Clean manholes/catch basins, repair damaged inlets/outlets, clean Vash racks. R99095-1340 Goldsmith & Associates Technicul h:fnrmatior�Report jnr d�e Pla�of+Ylaureen Hi,�hlund.c 10-3 APPENDIX A MAINT'ENANCE ST.aNDARDS FOR PRNATELY I�4AI�ITAINED DRAINAGE FACILITIES NO. 3 - CLOSED DETENTION SYSTEMS (PIPESlTANKS) Maintenance Defect Conditions When Maintenance Results Expected When Component Is Needed Maintenance Is Performed Storage Area Plugged Air Vents One-half of the cross section of a vent is blocked at Vents free of debris and any point with debris and sediment. sediment. Debris and Accumulated sediment depth exceeds 10%of the All sediment and debris Sediment diameter of the storage area for YZ length of storage removed from storage area. vault or any point depth exceeds 15%of diameter. Example: 72-inch storage tank would require cleaning when sediment reaches depth of 7 inches for more than��length of tank. Joints Between Any crack allowing material to be transported into All joints between tank/pipe Tank/Pipe Section facility. sections are sealed. Tank/Pipe Bent Any part of tank/pipe is bent out of shape more than Tank/pipe repaired or replaced Out of Shape 10%of its design shape. to design. Manhole Cover not in Place Cover is missing or only partially in place. Any open Manhole is closed. manhole requires maintenance. Locking Mechanism cannot be opened by one maintenance Mechanism opens with proper Mechanism Not person with proper tools. Bolts into frame have less tools. Working than'/z inch of thread (may not apply to self-locking lids). Cover Difficult to One maintenance person cannot remove lid after Cover can be removed and Remove applying 80 Ibs of lift. Intent is to keep cover from reinstalled by one maintenance sealing off access to maintenance. person. Ladder Rungs King County Safety Office and/or maintenance person Ladder meets design standards Unsafe judges that ladder is unsafe due to missing rungs, allows maintenance person I misalignment, rust,or cracks. safe access. Catch Basins See`Catch Basins"Standard No. 5 See"Catch Basins" Standard No. 5 R99095-1.340 Goldsmith & Associates Teclrnical Lijornru�ion Report for the Plat qf,bfaureen Highlands 10-4 APPENDIX A MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES NO. 4 - CONTROL STRUCTURE/FLOW RESTRICTOR Maintenance Conditions When Maintenance Results Expected When Component Defect Is Needed Maintenance Is Performed General Trash&Debris Distance between debris build-up and bottom of All trash and debris removed. (Includes Sediment) orifice plate is less than 1-1/2 feet. Structural Damage Structure is not securely attached to manhole wall Structure securely attached to and ouUet pipe structure should support at least wall and outlet pipe. 1,000 Ibs of up or down pressure. Structure is not in upright position (allow up to Structure in correct position. 10%from plumb)_ Connections to outlet pipe are not watertight and Connections to outlet pipe are show signs of rust. water tight;structure repaired or replaced and works as designed. Any holes--other than designed holes--in the Structure has no holes other structure. than designed holes. Cleanout Gate Damaged or Missing Cleanout gate is not watertight or is missing. Gate is watertight and works as designed. Gate cannot be moved up and down by one Gate moves up and down easily maintenance person. and is watertight. Chain leading to gate is missing or damaged. Chain is in place and works as designed. Gate is rusted over 50°�0 of its surface area. Gate is repaired or replaced to meet design standards. Orifice Plate Damaged or Missing Control device is not working property due to Plate is in place and works as missing, out of place,or bent orifice plate. designed. Obstructions Any trash,debris, sediment, or vegetation Plate is free of all obstructions blocking the plate. and works as designed. Overflow Pipe Obstructions Any trash or debris blocking (or having the Pipe is free of all obstructions potential of blocking)the overflow pipe. and works as designed. Manhole See"Closed Detention Systems"Standards No. See"Closed Detention Systems" 3. Standards No. 3. Catch Basin See`Catch Basins"Standards No. 5. See"Catch Basins"Standards No. 5. R99095-1.340 Goldsmith& Associotc� Tec�liiric'ul InJunnurinn Report Jor Nre Pla1 u%hfaureen Highla��ds 10-5 APPENDIX A MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES NO. 5 - CATCH BASINS Maintenance Defect Conditions When Maintenance Results Expected When Component Is Needed Maintenance Is Pertormed General Trash&Debris Trash or debris of more than 1/2 cubic foot which is No trash or debris located (Includes Sediment) located immediately in front of the catch basin immediately in front of catch opening or is blocking capacity of basin by basin opening. more than 10% Trash or debris(in the basin)that exceeds 1/3 the No trash or debris in the catch depth from the bottom of basin to invert the lowest basin. pipe into or out of the basin. Trash or debris in any inlet or outlet pipe blocking Inlet and outlet pipes free of more than 1/3 of its height. trash or debris. Dead animals or vegetation that could generate No dead animals or vegetation odors that could cause complaints or dangerous present within the catch basin. gases(e.g., methane). Deposits of garbage exceeding 1 cubic foot in No conditlon present which volume. would attract or support the breeding of insects or rodents. Structural Damage to Corner of frame extends more than 3/4 inch past Frame is even with curb. Frame and/or Top Slab curb face into the street(if applicable). Top slab has holes larger than 2 square inches or Top slab is free of holes and cracks wider than 1/4 inch(intent is to make sure cracks. all material is running into the basin). Frame not sitting flush on top slab,i.e.,separation Frame is sitting flush on top oi more than 3/4 inch of the frame from the top slab. slab. ' Cracks in Basin Walls/ Cracks wider than 1/2 inch and longer than 3 feet, Basin replaced or repaired to Bottom any evidence of soil particles entering catch basin design standards. through cracks,or maintenance person judges that structure is unsound. Cracks wider than 1/2 inch and longer than 1 foot No cracks more than 1/4 inch j at the joint of any inleU outlet pipe or any evidence wide at the joint of inleVoutlet of soil particles entering catch basin through pipe. cracks. SettlemenU Basin has settled more than 1 inch or has rotated Basin replaced or repaired to Misalignment more than 2 inches out of alignment. design standards. R99095-1.340 Goldsmith& Associates Technrcal Injormution Report jor the Plat of Muureen Highlands 10-6 APPENDIX A MAINTENAI`CE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES NO. 5 - CATCH BASINS (CONT/NUED) Maintenance Defect Conditions When Maintenance Results Expected When Component Is Needed Maintenance Is Performed Fire Hazard Presence of chemicals such as natural gas, oil and No flammable chemicals gasoline. present. Vegetation Vegetation growing across and blocking more than No vegetation blocking opening 10%of the basin opening. to basin. Vegetation growing in inleUoutlet pipe joints that is No vegetation or root growth more than six inches tall and less than six inches present. apart. Pollution NonFlammable chemicals of more than 1/2 cubic foot No pollution present other than per three feet of basin length. surface film. Catch Basin Cover Cover Not in Place Cover is missing or only partially in place. Any open Catch basin cover is closed. catch basin requires maintenance. Locking Mechanism Mechanism cannot be opened by one maintenance Mechanism opens with proper Not Working person with proper tools. Bolts into frame have less tools. than 1/2 inch of thread. Cover Difficult to One maintenance person cannot remove lid after Cover can be removed by one Remove applying 80 Ibs.of lift;intent is keep cover from maintenance person. sealing off access to maintenance. Ladder Ladder Rungs Ladder is unsafe due to missing rungs, misalignment, Ladder meets design standards Unsafe rust, cracks,or sharp edges. and allows maintenance person safe access. Metal Grates Grate with opening wider than 7/8 inch. Grate opening meets design (if applicable) standards. Trash and Debris Trash and debris that is blocking more than 20%of Grate free of trash and debris. grate surface. Damaged or Grate missing or broken member(s)of the grate. Grate is in place and meets Missing design standards. NO. 6 - DEBRIS BARRIERS (E.G., TRASH RACKS) Maintenance Defect Conditions When Maintenance Results Expected When Component Is Needed Maintenance Is Pertormed General Trash and Debris Trash or debris that is plugging more than 20%of Barrier clear to receive capacity the openings in the barrier. flow. Metal Damaged/Missing Bars are bent out of shape more than 3 inches. Bars in place with no bends more Bars than 3/4 inch. Bars are missing or entire barrier is missing. Bars in place according to design. Bars are loose and rust is causing 50%deterioration Repair or replace barrier to tn a^,,� part cf ba�rier design s?a�dar�<. k�i�Uv�-Li-lU Uuldi�iillh c� Assucialc• ,<<iuii<«r IrJ�,i�n+��n��n 1<rpuit/„r �i�� /'r�;r � ',11��nzc�� tir,ll��u��:, 10-7 APPENDIX A MAINTENANCE STANDARDS FOR PWVATELY MAINTAINED DRAINAGE FACILITIES NO. 7 - ENERGY DISSIPATORS Maintenance Defect Conditions When Maintenance Results Expected When Component Is Needed Maintenance Is Performed Extemal: Rock Pad Missing or Moved Only one layer of rock exists above native soil in Replace rocks to design Rock area five square feet or larger,or any exposure of standards. native soil. Dispersion Trench Pipe Plugged with Accumulated sediment that exceeds 20%of the Pipe cleaned/flushed so that it Sediment design depth. matches design. Not Discharging Visual evidence of water discharging at Trench must be redesigned or Water Properly concentrated points along trench(normal condition rebuilt to standards. is a`sheet flovY'of water along trench}. Intent is to prevent erosion damage. Perforations Over 1/2 of perforations in pipe are plugged with Clean or replace perforated pipe. Plugged. debris and sediment. Water Flows Out Maintenance person observes water flowing out Facility must be rebuilt or Top of"Distributo�' during any storm less than the design storm or its redesigned to standards. Catch Basin. causing or appears likely to cause damage. Receiving Area Water in receiving area is causing or has potential No danger of landslides. Over-Saturated of causing landslide problems. I nternal: Manhole/Chamber Wom or Damaged Structure dissipating flow deteriorates to 1/2 of Replace structure to design Post, Baffles, Side original size or any concentrated worn spot standards. of Chamber exceeding one square foot which would make structure unsound. Other Defects See"Catch Basins"Standard No. 5 See"Catch Basins"Standard No. 5 R99095-1.340 Goldsmith & Associates Teclti�icu!Injornration Report jnr the Plu�qf A1ai�reert HigJtfu�tds 10-8 APPENDIX A MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES NO. 8 - FENCING Maintenance Conditions When Maintenance Results Expected When i Defect Component Is Needed Maintenance Is Performed General Missing or Broken Any defect in the fence that permits easy entry Parts in place to provide adequate Parts to a facility. security. Erosion Erosion more than 4 inches high and 12-18 No opening under the fence that inches wide permitting an opening under a exceeds 4 inches in height. fence. Wire Fences Damaged Parts Posts out of plumb more than 6 inches. Posts plumb to within 1-1/2 inches. Top rails bent more than 6 inches. Top rail free of bends greater than 1 inch. Any part of fence(including post,top rails, and Fence is aligned and meets design fabric) more than 1 foot out of design alignment. standards. Missing or loose tension wire. Tension wire in place and holding fabric. Missing or loose barbed wire that is sagging Barbed wire in place with less than more than 2-1/2 inches between posts. 3/4 inch sag beriveen post. Extension arm missing, broken,or bent out of Extension arm in p1Ace with no shape more than 1 1/2 inches. bends larger than 3/4 inch. Deteriorated Paint or Part or parts that have a rusting or scaling Structurally adequate posts or Protective Coating condition that has affected structural adequacy. parts with a uniform protective coating. Openings in Fabric Openings in fabric are such that an 8-inch- No openings in fabric. diameter ball could fit through. NO. 9 - GATES Maintenance Defect Conditions When Maintenance Results Expected When Component Is Needed Maintenance Is Performed General Damaged or Missing Missing gate or locking devices. Gates and Locking devices in Members place. Broken or missing hinges such that gate cannot Hinges intact and lubed. Gate is be easily opened and closed by a maintenance working freely. person. Gate is out of plumb more than 6 inches and Gate is aligned and vertical. more than 1 foot out of design alignment. Missing stretcher bar, sVetcher bands,and ties. Stretcher bar, bands, and ties in place. Openings in Fabric See "Fencing" Standard No. 8 See "Fencing"Standard No. 8 RIyUJ�-1.3=1U Guldsmuh � .�ssoctates lech�iia�t hi�urnrutia�i/�eport,ior t/te!'!eu rg,�fuurec�i Higiilcu;�(• 10-9 APPENDIX A MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES NO. 10 - CONVEYANCE SYSTEMS (PIPES & DITCHES) Maintenance Defect Conditions When Maintenance Results Expected When Component Is Needed Maintenance Is Performed Pipes Sediment& Debris Accumulated sediment that exceeds 20%of the Pipe cleaned of all sediment diameter of the pipe. and debris. Vegetation Vegetation that reduces free movement of water All vegetation removed so water through pipes. flows freely through pipes. Damaged Protective coating is damaged; rust is causing Pipe repaired or replaced. more than 50%deteriora6on to any part of pipe. Any dent that decreases the cross section area of Pipe repaired or replaced. pipe by more than 20%. Open Ditches Trash&Debris Trash and debris exceeds 1 cubic foot per 1,000 Trash and debris cleared from square feet of ditch and slopes. ditches. ISediment Accumulated sediment that exceeds 20%of the Ditch cleaned/flushed of all design depth. sediment and debris so that it matches design. Vegetation Vegetation that reduces free movement of water Water flows freely through through ditches. ditches. Erosion Damage to See"Ponds"Standard No. 1 See`Ponds"Standard No. 1 Slopes Rock Lining Out of Maintenance person can see native soil beneath Replace rocks to design Place or Missing (If the rock lining. standards. Applicable). Catch Basins See"Catch Basins" Standard No. 5 See"Catch Basins"Standard No. 5 Debris Barriers See°Debris Barriers' Standard No. 6 See`Debris Barriers"Standard (e.g.,Trash Rack) No. 6 NO. 11 - GROUNDS (LANDSCAPING) Maintenance Defect Conditions When Maintenance Results Expected When Component Is Needed Maintenance Is Performed General Weeds Weeds growing in more than 20%of the landscaped Weeds present in less than 5%of (Nonpoisonous) area(trees and shrubs only). the landscaped area. Safety Hazard Any presence of poison ivy or other poisonous No poisonous vegetation present vegetation. in landscaped area. Trash or Litter Paper,can, bottles, totalling more than 1 cubic foot Area clear of litter. within a landscaped area(trees and shrubs only)of 1,000 square feet. Trees and Shrubs Damaged Limbs or parts of trees or shrubs that are split or Trees and shrubs with less than broken which affect more than 25%of the total 5%of the total foliage with split or foliage of the tree or shrub. broken limbs. Trees or shrubs that have been blown down or Tree or shrub in place free of knocked over. injury. Trees or shrubs which are not adequately supported Tree or shrub in place and or are leaning over,causing exposure of the roots. adequately supported; remove any dead or diseased trees. R99095-1 340 Goldsmith& Associates Teclmical/nfnnnutro�: Report for 1he Plat of Maureen Highlands 10-10 APPENDIX A MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES NO. 12 - ACCESS ROADS/EASEMENTS Maintenance Defect Conditions When Maintenance Results Expected When Component Is Needed Maintenance Is Performed General Trash and Debris Trash and debris exceeds 1 cubic foot per 1,000 Roadway free of debris which square feet, i.e.,trash and debris would fill up could damage tires. one standard size garbage can. Blocked Roadway Debris which could damage vehicle tires(glass Roadway free of debris which or metal). could damage tires. Any obstruction which reduce clearance above Roadway overhead clear to 14 feet road surface to less than 14 feet. high. Any obstruction restrictlng the access to a 10 to Obstruction removed to allow at 12 foot width for a distance of more than 12 feet least a 12 foot access. or any point restricting access to less than a 10 foot width. Road Surface Settlement, Potholes, When any surface defect exceeds 6 inches in Road surface uniformly smooth Mush Spots, Ruts depth and 6 square feet in area. In general,any with no evidence of settlement, surface defect which hinders or prevents potholes, mush spots, or ruts. maintenance access. Vegetation in Road Weeds growing in the road surface that are Road surface free of weeds taller Surface more than 6 inches tall and less than 6 inches than 2 inches. tall and less than 6 inches apart within a 400- square foot area. Modular Grid Build-up of sediment mildly contaminated with Removal of sediment and disposal Pavement petroleum hydrocarbons. in keeping with Health Department recommendations for mildly contaminated soils or catch basin sediments. Shoulders and Erosion Damage Erosion within 1 foot of the roadway more than 8 Shoulder free of erosion and Ditches inches wide and 6 inches deep. matching the surrounding road. Weeds and Brush Weeds and brush exceed 18 inches in height or Weeds and brush cut to 2 inches hinder maintenance access. in height or cleared in such a way as to allow maintenance access. R99095-1340 Goldsmith& Associates Teclinica!InJorn:atrnn Reparr for the Plut qf Maureen HiRhlands 10-11 APPENDIX A MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES NO. 13 - WATER QUALITY FACILITIES A.) Biofiltration Swale Maintenance Defect Conditions When Maintenance Results Expected When Component Is Needed Maintenance Is Pertormed Biofiltration swale Sediment Accumulation Sediment depth exceeds 2-inches No sediment deposits on grass on Grass Layer layer of the bio-swale,which would impede filtration of runoff. Vegetation When the grass becomes excessively tall Vegetation is mowed or nuisance (greater than 10-inches);when nuisance weeds vegetation is eradicated, such that and other vegetation starts to take over. flow not impeded. Grass should be mowed to a height between 4 inches and 9 inches. Inlet Outlet Pipe InIeU outiet pipe clogged with sediment and/or No clogging or blockage in the debris. inlet and outlet piping. Trash and Debris Trash and debris accumulated in the bio-swale. Trash and debris removed from Accumulation bioswale. Erosion/Scouring Wriere the bio-swale has eroded or scoured the Bioswale should be re-graded and bottom due to flow channelization,or higher re-seeded to specification,to flows. eliminate channeled flow. Overseeded when bare spots are evident. NO. 13 - WATER QUALITY FACILITIES (COfVT1NUED) B.) Grasslined Filter Strips Maintenance Defect Conditions When Maintenance Results Expected When � Component Is Needed Maintenance Is Performed li Filter Strip Sediment Accumulation Sediment depth exceeds 2 inches. No sediment deposits on grass layer on Grass Layer of the filter strip,which would impede filtration runoff. Vegetation When the grass becomes excessively tall Vegetation is mowed or nuisance (greater than 10-inches);when nuisance weeds vegetation is eradicated, such that and other vegetation starts to take over. flow not impeded. Grass should be mowed to a height beriveen 4 ; inches and 9 inches. Trash and Debris Trash and debris accumulated on the filter Trash and Debris removed from � Accumulation strip. filter. Erosion/Scouring Where the filter strip has eroded or scoured Strip should be re-graded and re- due to flow channelization, or higher flows. seeded specification,to eliminate channeled flow. Overseeded when bare spots are evident. V-Notch Pipe Weir When the V-North pipe becomes damaged or Cleaned and properly functioning clogged with sedimenU debris. weir, such that flow uniformly i spread. � R9yO9i-1.340 Goldsmith & Associates lechr�icnl b;/orrrtatiuri Repart fnr tlte Plut nJ A4aureen HiRhlurid.r 10-12 I APPENDIX A MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES C.) Wetponds Maintenance Defect Conditions When Maintenance Results Expected When Component Is Needed Maintenance Is Performed Wetpond Vegetation Vegetation such as grass and weeds need to be Vegetation should be mowed to mowed when it starts to impede aesthetics of pond. 4 to 5 inches in height. Trees Mowing is generally required when height exceeds and bushes should be removed 18-inches. Mowed vegetation should be removed where they are interfering with from areas where is could enter the pond, either pond maintenance activities. when the pond level rises,or by rainfall runoff. Trash and Debris Accumulation that exceeds 1 CF per 1000-SF of Trash and debris removed from pond area. pond. InIeU Outlet Pipe InIeU Outlet pipe clogged with sediment and/or No clogging or blockage in the debris material. inlet and outlet piping. Sediment Sediment accumulations in pond bottom that Removal of sediment from pond Accumulation in Pond exceeds the depth of sediment zone plus 6-inches, bottom. Bottom usually the first cell. Oil Sheen on Water Prevalent and visible oil sheen. Removal of sediment from pond bottom. Erosion Erosion of the pond's side slopes and/or scouring Slopes should be stabilized by of the pond bottom,that exceeds 6-inches,or where using proper erosion control continued erosion is prevalent. measures,and repair methods. Settlement of Pond Any part of these components that has settled 4- Dike/berm is repaired to Dike/Berm inches or lower than the design elevation, or specifications. inspector determines dike/berm is unsound. Rock Window Rock window is clogged with sediment. Window is free of sediment and debris. i Overflow Spillway Rock is missing and soil is exposed at top of Replace rocks to specifications. spillway or outside slope. i� I R9909i-1340 Goldsmith & Associates Techiticu!litforrnntrnn Report,fnr tlie Plar ojMu��reen Highlands 10-13 APPEI�DIX A '�1AINTENANCE STANDARDS FOR PRIVAT'ELY MAINTAINED DRAINAGE FACILITTES NO. 13 - WATER QUALITY FACILITIES (CONTINUFD) D.) Wetvaults Maintenance pefect Conditions When Maintenance Results Expected When Component Is Needed Maintenance Is Performed Wetvault Trash/Debris Trash and debris accumulated in vault, pipe or Trash and debris removed from Accumulation inleU outlet, (includes floatables and non- vault. floatables). Sediment Accumulation Sediment accumutation in vault bottom that Removal of sediment from vault. in Vault exceeds the depth of the sediment zone plus 6- inches. Damaged Pipes InIeU outlet piping damaged or broken and in Pipe repaired and/or replaced. need of repair. Access Cover Cover cannot be opened or removed, especially Pipe repaired or replaced to Damaged/Not Working by one person. proper working specifications. Vault Structure Vault: Cracks wider than 1/2-inch and any No cracks wider than 1/4-inch at Damaged evidence of soil particles entering the structure the joint of the inleU outlet pipe. through the cracks,or maintenance/inspection Vault is determined to be personnel determines that the vault is not structurally sound. structurally sound. Baffles Baffles corroding,cracking,warping and/or Repair or replace baffles to showing signs of failure as determined by specifications. maintenance/inspection staff. Access Ladder Ladder is corroded or deteriorated, not functioning Ladder replaced or repaired to Damage properly, missing rungs, has cracks and/or specifications, and is safe to use misaligned. as determined by inspection personnel. APPENDIX A MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES NO. 13 - WATER QUALITY FACILITIES (CONT/NUED) E.) Sand Filters Maintenance Conditions When Maintenance Results Expected When Component �fect Is Needed Maintenance Is Performed Above Ground Sediment Sediment depth exceeds 1/2-inch. No sediment deposit on grass Accumulation on Grass layer of sand filter which would Layer impede permeability of the filter section. Trash and Debris Trash and debris accumulated on sand filter bed. Trash and debris removed from Accumulations sand filter bed. Sediment/Debris in When the yard drain CB's and clean-out become Sediment,material from the CB's Yard Drains/Clean- full or partially plugged with sediment and/or and clean-outs removed. Outs] debris. Vegetation When the grass becomes excessively tall (greater Vegetation is mowed or nuisance than 6-inches);when nuisance weeds and other vegetation is eradicated, such vegetation starts to take over. that flow is not impeded. Sand Filter Media Drawdown of water through the sand filter media, Usually requires replacement of takes longer than 24-hours,and/or flow through top 6 to 12-inches of inedia. the overflow pipes occurs frequently. May require replacement of entire sand filter section,depending on section. Prolonged flows Sand is saturated for prolonged periods of time Limit the low,continuous flows to (several weeks) and does not dry out between a small portion of the facility by storms due to continuous base flow or prolonged using a low wooden divider or flows from detention facilities. slightly depressed sand surface. Short Circuiting When flows become concentrated over the sand Flow and percolation of water filter rather than dispersed. through the sand filter is uniform and dispersed across the filter section. Erosion Damage to Erosion over 2-inches deep where cause of Slopes should be stabilized by Slopes damage is prevalent or potential for continued using proper erosion control erosion is evident. measures. Rock Pad Missing or Soil beneath the rock is visible. Replace or rebuild the rock pad to Out of Place design specifications. V-Notch Pipe Weir When the V-Notch pipe becomes damaged or Clean and properly functioning clogged with sedimenV debris. weir, such that flows uniformly spread. Damaged Pipes Any part of the piping that is crushed or deformed Pipe repaired or replaced. more than 20%or any other failure to the piping. Below Ground Sediment Sediment depth exceeds 1/2-inch. No sediment deposits on sand Vault. Accumulation on Sand filter section,which would impede Media Section permeability of the filter section. Sediment Sediment depth exceeds 6-inches in vault bottom. No sediment deposit in the first Accumulation in Vault chamber of the vault. Trash/Debris Trash and debris accumulated in vault, or pipe Trash and debris removed trom Accumulation inleU outlet, floatables and non-floatables vault, and inleU outlet piping. Sediment in Drain When drain pipes,cleanouts, and yard drains RemovF the marP�ial from t�� Pi�es?Yard Drains� become full with sediment andr or debris. facilit��- ky`JUyJ-1_i-�U Gultlsiuuh ck Assonn[cs Iec'nnii<il l��jurmc�urm kepur;)ur liie Ptcu uf;Llw�reen N�giilcuuls 10-15 APPENDIX A MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES NO. 13 - WATER GIUALITY FACILITIES (CONTINUED) E.) Sand Filters (Continued) Maintenance Defect Conditions When Maintenance Results Expected When Component Is Needed Maintenance Is Performed Below Ground Short Circuiting When seepage!flow occurs along the vault walls Sand filter media section re-laid Vault(Continued) and corners. and compacted along perimeter of vault to form a semi-seal. Vertical Riser Pipes Plugged,failure due to cracking deformation. Flows Clean out the riser pipe; replace tend to back-up in first chamber of the vault. pipe as needed. Damaged Pipes Inlet or outlet piping damaged or broken and in need Pipe repaired and/or replaced. of repair. Access Cover Cover cannot be opened,one person cannot open Cover repaired to proper Damaged/Not the cover,corrosioN deformation of cover. working specifications or Working replaced. Vault Structure Cracks wider than 1/2-inch and any evidence of soil Vault replaced or repaired to Damaged; Includes particles entering the structure through the cracks, design specifications. Cracks in Walls, or rnaintenance/inspection personnel determines Bottom, Damage to that the vault is not structurally sound. Frame and/or Top Slab. Cracks wider than 1/2-inch at the joints of any infeU No cracks more than 1/4-inch outlet pipe or any evidence of soil particles entering wide at the joint of the inleU the vault through the walls. outlet pipe. Baffles Baffles corroding,cracking,warping and/or showing Repair or replace baffles to signs of tailure as determined by maintenance/ specifications. inspection person. Access Ladder Ladder is corroded or deteriorated, not functioning Ladder replaced or repaired to Damaged properly, missing rungs, cracks, and misaligned. specifications, and is safe to use as determined by inspection personnel. R99095-1340 Goldsmith&Associa[es Technical Information Report for the Plat of Maureen Highlands 10-16 APPENDIX A MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES NO. 13 - WATER QUALITY FACILITIES (CONTlNUED) F.) Leaf Compost Filters Maintenance pefect Conditions When Maintenance Results Expected When Component Is Needed Maintenance Is Performed Above Ground Sediment Sediment depth exceeds 0.25-inches. No sediment deposits on fabric Open Swale accumulation on Geo- layer which would impede Textile/media permeability of the fabric. Trash and debris Trash and debris accumulated on compost filter Trash and debris removed trom accumulations bed. compost filter bed. SedimenU debris in When the yard drain CB's and clean-outs become Remove the accumulated material drain/yard drains/ full of sediment and/or debris. from the facility. clean-outs. Vegetation Vegetation impending flow through section,or Vegetation is mowed or encroaching into compost media. eradicated such that flow is no longer impeded. Leaf Compost Media Drawdown ot water through the leaf compost, Replace media with new to takes longer than 12-hours,and/or How through design specifications, in addition the overtlow pipes occurs frequently. to replacing fabric. Short-Circuiting When Channeled flow occurs over the leaf inedia; Flow is uniform over the entire and where flow perks through the media at the width of the media section,and baffies. concentrated percolation does not occur at the baffle walls. Media needs to be graded and re-set at the baffles to form a seal. Weir plate may need to be adjusted in addition. Erosion Damage to Eroded damage over 2-inches deep where cause Slopes should be stabilized by Slopes of damage is prevalent or potential for continued using proper erosion control erosion is prevalent. measures. Damaged Geo-Textile When fabric is torn,deteriorated, raveled, etc. Fabric replaced as necessary. Fabric. Rock Pad Missing or Soil beneath the pad is visible. Replace or rebuild the rock pad to out of place design standards. Damaged Pipes Any part of the pipe system that is crushed, Pipe repaired or replaced. damage due to corrosion, and/or settlement. V-Notch Weir Flow is not being uniformly spread over filter Clean, repair or replace the weir Assemblies media. systems. Below Ground Sediment Sediment depth exceeds 0.25-inches. No sediment deposits on fa Vault Accumula6on on Geo- layer which would impede Textile/Media. permeabiliry of the fabric ar compost media. Sediment Sediment depth exceeds 6-inches in first No sediment deposits in vault Accumulation in Vault chamber. bottom of first chamber. Trash/Debris Trash and debris accumulated on compost filter Trash and debris removed from Accumulation bed. the compost filter bed. Sediment in Drain When drain pipes,clean-outs, yard drains Remove the accumulated material Pipes/Yard Drains/ become full with sediment and/or debris. from the facilities. Clean-Outs R99095-1340 Goldsmith&Associares Technica!Liformation Report,for the P(at of Mauree»Highlands 10-17 APPENDIX A MAINTENANCE STANDARDS FOR PRNATELY MAINTAINED DRAINAGE FACILITIES NO. 13 - WATER QUALITY FACILITIES (CONTINUED) F.) Leaf Compost Filters (Continued) Maintenance Defect Conditions When Maintenance Results Expected When Component Is Needed Maintenance Is Performed Below Ground Leaf Compost Media Drawdown of water through the leaf compost,takes Replace media with new longer than 12-hours, and/or overflow occurs compost to specifications, in frequendy. addition to replacing fabric. Short Circuiting When seepage occurs along the vauft wall and Percolation of water occurs corners occur. along the walls and comers and not through the media section. Media needs to be re-set along the vault wall and comers to form a semi-seal. Plugged/Damaged Flow tends to backup unusually high in the first Clean out the elbow fittings and/ Elbows chamber of the vault. or replace if damaged. Damaged Geo-Textile Fabric is tom,deteriorated, raveled, etc. Fabric replaced as necessary. Fabric Rock Pad Missing or Soil beneath the pad is visible. Fieplace or rebuild the rock pad Out of Place to design standards. Damaged Pipes Any part of the pipes that are crushed,damaged Pipe repaired and/or replaced. due to corrosion and/or settlement. Access Cover Cover cannot be opened,one person cannot open Cover repaired to proper Damaged/Not the cover, corrosion/deformation of cover. wo�lcing specifications or Working replaced. V-Notch Weir Flow does not spread uniformly over filter media by Clean, repair and/or replace the Assemblies weir section. weir plate section, or adjust height. � Vault Structure Cracks wider than 1/2-inch and any evidence of soil Vault replaced or repaired to Includes Cracks in particles entering the structure through the cracks, design specifications. li Wall, Bottom, or maintenance/inspection personnel determines � Damage to Frame that the vault is not structurally sound. and/or Top Slab Baffles Baffles corroding,cracking warping, and/or showing Repair or replace baffles to signs of failure as determined by maintenance/ specification. inspection person. Access Ladder Ladder is corroded or deteriorated, not functioning Ladder replaced or repaired and Damaged properly, missing rungs, cracks, and misaligned. meets specifications,and is safe to use as determined by inspection personnel. Cracks wider than 1/2-inch at the joint of any No cracks more than 1/4-inch inleVoutlet pipe or any evidence of soil particles wide at the joint of the inleV entering the vault through the walls. outlet pipe. R99095-1.340 Goldsmith&Associates Technical/nformation Report for the Plat of Maureen Highlands 10-18 APPENDIX A MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES NO. 13 - WATER QUALITY FACILITIES (CONTINUED} G.) Infiltration Ponds Maintenance Defect Conditions When Maintenance Results Expected When Component Is Needed Maintenance Is Performed Infiltradon Pond Vegetation Vegetation such as grass and weeds needs to be Vegetation should be mowed to mowed when it starts to impede infiltration function. 2-inches in height. Trees and Mowing is generally required when height exceeds bushes should be removed 12 inches. where they impact the infiltrating area of the pond. Sand Filter Layer Sand filter layer has sediment deposits that exceeds Remove sediment and top Iayer 1/2-inch or the infiltration rate of the sand layer is of sand,and replace in kind per less than 2 in./hr. specification. Sediment Sediment accumulations in pond bottom that Removal of sediment from pond Accumulation in exceeds 1/2-inch in depth or percolation test of the bottom. Pond Bottom pond indicates facility is only working at 90%of iYs design percolation rate. Trash and Debris Accumulation that exceeds 1-CF per 1,000-SF of Trash and Debris removed from pond area. pond. InIeV Outlet Pipe InIeU outlet pipe clogged with sediment and/or No clogging or blockage in the debris material. inlet and outlet piping. Erosion Erosion of the pond's side slope and/or scouring of Slopes should be stabilized by the pond bottom,that exceeds 2-inches,or where using proper erosion control potential for continued erosion is prevalent. measures and repair methods. Sediment of Pond Any part of these components that has settied 4- Slopes should be stabilized by Dike/Berm inches or lower than the design elevation,or where using proper erosion control potential for continued erosion is prevalent. measures and repair methods. Rock Window Rock window is clogged with sediment. Window is free of sediment and debris. Overflow Spillway Rock is missing and soil is exposed Replace rocks to specifications. Infiltration VaulU Sediment Tanks: Sediment depth exceeds 6-inches in depth. No sediment deposits in tank Tank Accumulation in bottom. Vault Trash and Debns Trash and debris accumulated in tank, vautt or Trash and �� Accumulation connecting pipe. Includes floatables and non- each facility. floatables. Access Cover Cover cannot be opened or removed, especially by Cover repaired or replaced to Damaged/Not one person. proper working specifications or Working replaced. Tank or Vault Tank: Joints between tank sections failing, such Tank replaced or repaired to Structure Damaged that leakage occurs and. or material being washed design specifications. through into facility;or maintenance/inspecbon person determines the tank is not structurally sound. R99095-1.340 Goldsmith&Associates Tech�ircul Infonnation Report fnr the Plcit of Mauree�t Hrghlunds 10-19 APPENDIX A MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES NO. 13 - WATER (�UALITY FACILITIES (CONT/NUED) G.} Infiltration Ponds (Continued) ' Maintenance Conditions When Maintenance Results Expected When �� Component Defect �S Needed Maintenance Is Performed Infiltration VaulU Tank or Vault Structural Vault: Cracks wider than 1/2-inch and any Tank replaced or repaired to Tank Damage evidence of soil particles entering the structure design specifications. through the cracks, or maintenance inspection personnel determines that the vault is not structurally sound. Access Ladder Damaged Ladder is corroded or deteriorated, not Ladder replaced or repaired to functioning properly, missing rungs, has cracks specifications, and is safe to use and/or misaligned. as determined by inspection personnel. R9909�-1.340 Goldsmith &Associates Teclutica!Ltforntation Report for the Plat of Maureen Hlghlands 10-20 APPENDIX A MAINTENAIv'CE STANDARDS FOR PRNATELY MAINTAINED DRAINAGE FACILITIES NO. 14 - OIL CONTROL FACILITIES A.) OiUWater Separators Maintenance Defect Conditions When Maintenance Results Expected When Component Is Needed Maintenance Is Performed API Type OWS Monitoring Inspec6on of discharge water for obvious signs Effluent discharge from vault of poor water quality. should be clear with out thick visible sheen. Sediment Accumulation Sediment depth in bottom of vault exceeds 6- No sediment deposits on vault inches in depth. bottom which would impede flow through the vault and separation efficiency. Trash and Debris Trash and debris accumulation in vault,or pipe Trash and debris removed from Accumulation inleU outlet,floatables and non-floatables. vault, and inleU outlet piping. Oil Accumulation Oil accumulations that exceed 1-inch, at the Extract oil from vault by surface of the water vactoring. Disposal in accordance with state and local rules and regulations. Damaged Pipes Inlet or outlet piping damaged or broken and in Pipe repaired or replaced. need of repair. Access Cover Damaged/ Cover cannot be opened, one person cannot Cover repaired to proper Not Working open the cover,corrosion/deformation of cover. working specifications or replaced. Vault Structure Damage- Cracks wider than 1/2-inch and any evidence of Vault replaced or repaired to Includes Cracks in Walls soil particles entering the structure through the design specifications. Bottom, Damage to cracks,or maintenance/inspection personnel Frame and/or Top Slab determines that the vault is not structuraliy sound. Baffles Baffles corroding, cracking,warping and/or Repair or replace baffles to showing signs of failure as determined by specifications. maintenance/inspection person. Access Ladder Ladder is corroded or deteriorated, not Ladder replaced or repaired and Damaged functioning properly, missing rungs,cracks,and meets specifications,and is misaligned. safe to use as determined by inspection personnel. Cracks wider than 1/2-inch at the joint of any No cracks more than 1/4-inch inleU outlet pipe or any evidence of soil particles wide at the joint of the inleU entering the vault through the walls. outlet pipe. CPS-Type OWS Monitoring Inspection of discharge water ior obvious signs Effluent discharge from vault of poor water quality. should be clear with no thick visible sheen. Sediment Accumulation Sediment depth in bottom of vault exceeds 6- No sediment deposits on vault inches in depth and/or visible signs of sediment bottom and plate media, which on plates. would impede flow through the vault and separation efficiency. Trash and Debris Trash and debris accumulated in vault, or pipe Trash and debris removed f�c� Accumulation inleU outlet,floatables and non-floatables. vault,and inleU outlet pipir; Oil Accumulation Oil accumulation that exceeds 1-inch at the Extract oil from vault by water surface. vactoring methods. Clean coalescing plates by thoro� rinsing and flushing. Should c: no visible oil depth on water. R99095-1340 Goldsmith&Associates Technical Information Report for the Plat of Maureen Highlands 10-21 APPENDIX A MAINTENANCE STANDARDS FOR PRIVATELY MAINTAINED DRAINAGE FACILITIES � � NO. 14 - OIL CONTROL FACILITIES (CONT/NUED) A.) Oil/ Water Separators (Continued) Maintenance Defect Conditions When Maintenance Results Expected When Component Is Needed Maintenance Is Performed Damaged Coalescing Plate media broken,deformed,cracked and/or Replace that portion of inedia Plates showing signs of failure. pack or entire plate pack depending on severity of failure. Damaged Pipes Inlet or outlet piping damaged or broken and in need Pipe repaired and or replaced. of repair Baffles Baffles corroding,cracking,warping and/or showing Repair or replace baffles to signs of failure as determined by maintenance/ specifications. inspection person. Vault Structure Cracks wider than 1/2-inch and any evidence of soil Vault replaced or repaired to Damage- Includes particles entering the structure through the cracks, design specifications. Cracks in Walls, or maintenance inspection personnel determines Bottom, Damage to that the vault is not structurally sound. Frame and/or Top Slab Access Ladder Ladder is corroded or deteriorated, not functioning Ladder replaced or repaired and Damaged properly, missing rungs, cracks, and misaligned. meets specifications,and is safe to use as determined by inspection personnel. Cracks wider than 1/2-inch at the joint of any inleU No cracks more than 1/4-inch outlet pipe or any evidence of soil particles entering wide at the joint of the inleU the vault through the walls. outlet pipe. B.) Catch Basin Inserts Maintenance Conditions When Maintenance Results Expected When Component Defect Is Needed Maintenance Is Performed Catch Basin Sediment When sediment forms a cap over the insert media of No sediment cap on the insert Accumulation the insert and/or unit. media and iYs unit. Trash and Debris Trash and debris accumulates on insert unit creating Trash and debris removed from Accumulation a blockage/restriction. insert unit. Runoff freely flows into catch basin. Inspection Inspection of inedia insert is required. Effluent water from media insert is free of oils and has no visible sheen. Media lnsert-Water Catch basin insert is saturated with water, which no Remove and replace media Saturated longer has the capacity to absorb. insert Media lnsert-Oil Media oil saturated due to petroleum spill that drains Remove and replace media Saturated into catch basin. insert. General Regular interval replacement due to typical average Remove and replace media at life of inedia insert product. regular intervals,depending on insert product. R990yS-].340 Goldsmith & Associates 7�e��ltiucu!h{Jnnnatiun Reporv fnr the Plut o(,ti7uureert HiKhland.r 10-22 Appendices A King County Sensitive Area Folios B Proposed May Creek Basin Action Plan Basin Maps Appendix A King County Sensitive Area Folios '�t� r ; �-_-� -1�:� ... .. �T�,/,. -'=v�\�, _ � �� l r - f� �^ ��r, .b.�`"'" - i., 'r.' 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'.,� � � ;� ,. � . -� _ ' l b � - Coe � ' �:: 'J 's_ '�\ • �� , � '�-:" - -'`�s � - �-.� , _�� ., 'I !sn y�ao�\I� !, ' K - ' � ' �\ � i � � I \ 1 - -� _ , r �_ � i f71bD1ts G� �s� -- � `, ` � kY` � , `. `Y � �1� ,� � � � �� ;- c -_� _ � 'J.l �' � i l: �..� ti . �. _ s. `�:�� *�; __ ;`�� `-, , 1 .�' `� i;r bl� - r ' , 1 " �` Y . 1� �1 1 '` " � > � i`; _ } .�� . \ f , y�.' * � � � � � � I ' _ �� '� �,��, _ �\ � }.� �a ' Y `�v _ � \�� _ _`` / �� ✓ i � �J _ \ 1 �,� \ i E -'� _ � �X � � " �� - �'' �' �i �• .� _ J' ��r �� :��_s� ,J'�r�.,�� '�'� - _ . �'��,' �Z�_� .� '.� � /� �.�� a. .: �. � � ..� _ -�c � _ ! �� `.�'�' ��" _ ,i �,:t ' ��.•� \\ -�, .I �:. ��.E _ /,.._- .�� ;y��'�'' ',��.�. ' �: �\ O`a �.\< � �`'�� /r T� . '/'� /`r � � _ 1 — 3 � �i ' � �a ��r� �'' -" � -.- r ,1 � .\� i � t . � \ • `� ' - ' - ` �'� ,�` �� I��-\ a -- � � �s 11 � .� ,� � � � � _�. � �... � , �,+ a-. -`c , . � , - � � � '\�'IA) � �� '�� :� �. - � � � `S` '� �. 2Eb9 ' '�� - '� �` � I f' Y1 _ `` l t� �• �5`I4 i - _ - '- G' - I `-� _ k �i� \` �� Z _6'.. � ` �� 'y�x% ',� . , - , � IT' � : _ �� , ,�_\ _ -� ',."� �-��, � �F� _zaa , �^; -�, 4„ - – � '��`v,. � r � b i L � ��.t-�� , '' \ � � � -- I _ � . \= - ` _ _ � 1\ FI 't 1 r^ \�: p' ,� .` ' � ��,; �\ � . ` r�" � � .�:� � +X i� � \'• � 1� ��~ r 'i �._ l'1 .E. �', `� > �.. �\ � �� ? 4 ��., t a '� --X '�\ i 'w ` , '.��'� �_ �' _ �'. _� ' +J . �r "�''� s��, I� 1 ��. � � .r �- ' �-� -� _ +;, I � _ .. � , i ` �._ '__ - _ �.;T' r._ ./ �� .O . 4F:. �� '.\ �sa ��`�'�s � + 1 �\ .'�� - �' \`.7 � � �J' .i.-,i i � 1 .\ r � - .'.r�� -1 : 1� : ' 'l0. �� _ -��_�. i F y ,.� � �.' '(^t �• c.V'�-� � . . ,.-J' � � � . � �� ' �'.: '. �.. : � . J� I _ �.. - �T. � � 1 -`` . t _ � 1 �� - ` `af• � � I) � t. \ � '� : 1 l 1 r 1 , �.•y �. - � _ �-"�' -�� h- � r t . , �. _ . ' �. ' �.*+ ,� �i i� � �(L 'r -_� �" - . t =�--�� , �{ � � I � �� _i-� � =T -�� _ . / ''tv �. . u� . �� \�'. ' - � :�� `� '��` } (? � � � .� `8_=' /��-403 � `�' s � �� \ . 1 � � �.� 37 .��]�� r y ` ;,'� ' �� _,�� T-„ `�.�: 'a I� f I � � `'�� -- `�. � �. f ' ' ' _ �^ fl �...- _ -1' � t -, a.�: __ I l.x.� 1`' i. �� , �� -_� � _ � v, r'.` 1�- ' 1 �`. �` "C��1RC�?_ `t -� �, I_ .� • ; . +' f�� .�:�. . `�� :� �� -- .� i ' Y'- ..� , .� - -- ��- !r � _' i�� '�` " �;t c - I t; �, : _.� � �� \��_ � - ' , ;`B � _ � -1 �• - _ , Z� � . ,--,. •�. 1,. ` — - , +� . ^; � � - _� _ ,r= - �o' ��:�.� .�� ..� . � L � ��2 0 � The boundaries of the sensitive a►eas dis- Numberetl wetlantls, except playetl on these maps are approximate. "a" or "b" designation are t I� i � Additional sensltive areas that have not Kinp County Wetlands /n been mappetl maY be present on a devel- �a�ations oi wetlands desig MILE � opment proposal site. Where ditferences been verified on the site f occur between what is illustrated on these sources. Wetlands desi9nate maPs antl the site conditions, the actual pre- Ped in the U.S. fish and � sence or absence on the site of the sensitive Nationa7 Weilands Inventor, area - as defined in the Sensitive Area tions have�ot been field ver WETLANDSOrdinance-is the legal control. There may be gaps in the . quence within intlividual SOURCE: SENSITIVE AREA MAP FOLIO, KING COUNTY, WA - 1990. ' � �;t.� (��--� � � •�- ��p `��, �� • ��° ��• ��et,�� f=�� :�r+� , �s �!>s ��. \ - L (� w,• � �� '!'� � ''_�a�ilEl�1��'�:. �� - ��, _ �,� e � v "� �� , ��F-_'' `.� ti 1 .�!!� - ` �t ' '�-�F � (- ;� •� �� t�� re: � :� h �,; i�;� �� 9�� ,. �>" � j ,;�y � � 4.� 0� y� � � ,1� '� \ � �� y. � � �► �i°rr �� 'T% ' '.�" �-\�, �s;•:-, � :� A� �• "`r"' �� , _t�:e_ �� _ �"'_ ' � � ��- ..� � � _� � � � a �,. 1� � �� <<7 � � p.! 1 .�-� � �� ` , �F �� t� ,� _ - _�. �,: � , .. �, � �. � _ .��. �� .. �� -�;. �� : ��-:- �� -�� - �� ;�� a� _ � ` : .�� J ,,,� �-� ' �'r� �l1�. :. � �•s � � ;, `� ti'_�... �e' "��'�E '.�� 4`�� o' � ;;�:� ;` 4.0 '�o ?� �a��yG �� ;/:� �, �;�yl:- ;�., _ �`�`'`� � ��,` i.--.��1� ',� �6''t � � - .3 _�� 6r �� :#+: /L�' ti• _ --�c '"� • ► �� a*_* f ��ry %` 'i '�. ��. - �F��s��< �� 5. �. �.� - � ��. � �y a 'a�`- �� ,�� , �^�" '`�� ' ' .� _ �•�� '�• •� %� 4` :"�i .:-�� •,}'�'` �� V� � �� rr�� E � .'s- i £�.�A �j ��v� '.�l.^S', 4 _ ��'e a �: J�� . `� �;�=�- :�,�'',' � �� '� � E �� .� �, I f'�4 .f ' �. �;• * - ��.. j�� , '� *- Iy �� !� - ,� i1�j* �., g3?�.�.j.� • �, '! � - '�' ��-�iu�'t��'" � �' �. � ' � +. { _ � 'O' < f ' . ��. .i� �Si�'�� (��! =g s+e�e� ��`� �i� `_��y �u �' ��-�'- � +�, � �`'��ss� S i� � � `a \ �'�+�rF G� E.. aa�A,,,,i Z l��. `�� .. �- : y 'T e�d ', ��9�� "•��_'. �'�' � � l�C� "� 'y yr'. 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V _ Y .� ��.� Ry �yj'� �, .,. , � ' �� 'j - - S/T� �,_` ��,^, .� �, �� ,�� , , r � ' � � :_ � _ �� , � � ! '�V �� :- �, :\ � �``� � `,� �� r1 \ I=�f� �\� �� \�1- \ �' .� �-�-��e • � r F \\ � .t� � �.1�'� y ;�� ' �:�:•� I �� j^ U ��\', \\.-.. a` . . . � ,:. + <. "1. E T� 9'{'1a y �� 11 �� - �� ' r�. r 'e ..� . i. - - .�, '`A \ �- �: � / r �:-- - �-. � , '.�r r �`�S, � \ �' `� �-��•i 1�'. �� \` �'= I I 'r"`.-� '� �' � `, � .� � ` :` �� =�r -0j "' ��' �^ � ��' � - � �''` .,� �;xy ��``�' �•' � � `� r' ��I � -w� ,3�� s. : � u 'r :� � �• � i .'�� J. . �' _" � � ' _i I �(� �II�� ,i� I _ : � . \ �. /�iJ 1° �; r� �`:.. % -\: , 1 � \ `.., �-v �.,l �-�.; J ;,. �� r _`` ••' _ ,a. _ � f � - �� ' �,' ;\.�-� -i� ��i '. � r �r ,� \ < 3 v • r, _�1,r _ . �� 1 �`�� ,, Y .� 'i�Fa � �t `yn.=� ' •.��__ __�y* i ��/ � ..� .\I ,�' �-._ �. �` �1. S �r., ' � � \ . �`�� 1. _ � r -_ - ' ' - r, � ', � � - yj��^ ~ � - - � - - � Z � I I \ v--.� `� �� _ z� -. ; _ _' \:� •` . � � , I -� � -�'t. ---, � a=t ��' 1 ;-,r � � ` ":.�`�; , r-4"� - , � ' _ � r = r �, ', � t,v- 1 � � - � 1 ' -` '=\ \` �• - - � , �� " � . ` ` : �,t. � _� 1�� ♦ � � � ��r ` j a� -� ��i j .�a `=- xi'\ . �-y �' l,; T �� - ,_`- I � _� _} : �. I t \•. C , ` �jr-_�� ;-•' I1 `,_ ��: '/r- � -�.. � .i .rl� '�,.. -�' ��, \,<-, � / '�s . 'r. . �\ . � 1- ._ ,.,, ,�la . �- -f:; L � w � �r.�m�c- .�� ..� s :�- � �� The boundarles of the sensitive areas dis- One- huntl►ed-yaa► tloOdpl played on these maps are approximate. Yond those shown on m< I � I i � Adtlitional sensltive areas that have not suranee Rate Maps do not • been mappetl may be Present on a tlevel- 1loodplaln to the headwat MILE � opment proposal sfte. Where tlifferences I occur between what is illustrated on these STREAMS & maps and the site conditions, the actual pre- sence or aDsence on the slte of the sensitive area - as defined in the Sensitive Area FLOOD HAZARD AREAS orainance-is tne legal control. � ��Y�� ISOURCE: SENSITIVE AREA MAP FOLIO, KWG COUNTY, WA - 1990; rc �7o'-w- .,. ..� . :.r. .. ��I Yo L-._'. - - . '--1' � � - �� ... i R^,,, � '_ '- ��' 7� �{{ �^ ..�.e..,� � r . 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C��r L ' .„ ' - . - '_. � _ / � �-_� ' :�•+�y��.� _ — - - - �� -_ �� _ /� � ,l -'F � � I1 / �� " ,,.�+u j,� �: - r i � O � ��✓�rf .:�� - �' !� � � x � � � °^` ~' '� .\�,��. � 7-�-��+�� y s I t. - ' �� _� - li_ �� . � �- �y',.� �.\��. � � .i% '(i�,ir..�„` � :�-•� 1 � .� \ aq,!.. �'\ !t � r� y� 4 � - f• �_ � �` lF y \��;h� {�`�'.�'� ��, '.Q5 9 `; — _ � _ �- � ` ` `�G\�� ' t .,. � � t - .\` - � `J , ,� J � .'� _ , r.J f. � � � _ _ _ , �'�� ,;_ _ ""� � � �� ,� ;. •S/T�1 � ,� � � -� � , �, ��- �-,= � ;,� _ ., � _� � �� _, ' �' ;� _ , �� 1�_ _ � � .� - . � 9 ' � � ,��r � � � � � ' � '\ � � 1 '� '��, i �` ' � �. � s�.��t � ; � � � � � _ _ � .. r.. '1G - -.11. E _ -� � h� \ - _ � r� �. .�� c._.,#it ' 1 1 I`S i ..' " 1��_'_ 1` _ _ _ '�,�� I �, ��3� � `� ' \� � � `.. � �:- :t �� i ��' � � i�'. �Jy � ��. j �= 1 + �/ � .+ .} ....: \I �' � - � .;� - .:.: �..� � . , � i � '- �'S � - ` , � u. .. A .,i..�,� ��\ i(-- l�:.� � __!a- '. .I � q� �. \ _� � ' � ''� a�� : �u 1 '� � _, ��,� � � r.. ,�� '' � , � � i � � r � `i `�� , - �'�+ ' ,. '1`�' � � . � - l -{-: - � 1 4 Y �. t:. 4:. -\. 1. +� 11 � . : r: � ��- �\ ..� _ �-^ � � .. � .�' � � � ;j � , r ;.� I 41 � � � �J� �l'• '` ` ��, � ,� t9� J� � � ' � �. u ,.� .�� - ��- �.. �q.�_�,-��:.� , _ _ � i ` -� ,;^ ,. _ ;` �`` :� Y w ti .� 4 --�:� r � '^�r - 1_� �_.� I ..a...-_ __ - _ ; i'\... ;,1� .`1 � _� 1 � 1 ` \` , �. � N{ . ] l:�� ` � 1 , 1� _ •. � ��. I � ,Y� / `.�. �. I � � - f .` ~� `F �'y � tl �� _� r/ . i -�` ` . � y\� -/ � � .� . �. . .� � .i� �- F . �� C'` ��rf . ' 1... ,r �\ �, � � \�, Y rrJ'y : '1 . I 1 �� .� � �� s * --. \�1' :.. �a�. � . / �� -,. . vi „ �` �_ . . .-. ..� - • . . . L �p ;nanr ' . ..�� y _ . -yY 1 1/2 0 � The boundaries of the sensitive areas dis- playetl on these maps are approximate. � i i ___ i Additional sensitive areas that have not been mappetl maY be present on a devel- MILE � opment proposal site. Where differences � occur between what is illustratetl on these maps and the site conditlo�s,the actual Pre- � sence o! absence on the site of the sensftive LANDSLIDE HAZARD AREAS Ortlinance-�Is the egal controlensitive A.� SOURCE: SENSITIVE AREA MAP FOLIO, KING COUNTY, WA — 1990 � . - _ _ - _ --_ .J =�' � � � ,.,� � �_ �;_, , r. . � -� '�/�.�,..-m.a..� L. •�. � Z � �.� � h;, . ''_ ` _ I - ,,i�_ '� t - .�.k � ;;� ��,, , � ' � :� r� ,��,�� ` �� - — i -- ,;+ ''�?� 1 ' , a.+...--� � '�cs `� 1 t S- -n.f � � � . �. \: 1 � � _ r� S f ��` . • ��` �'�_� �� ,,, -;. ' :l >:' �3 ��,- '"� �! \ � ,-�. �,` �� . f r � .�� ._�#. . � I 1 � � rr1 ''r' ��'1 i`- � ..�_� :�, c ' � � � � �� r � J� - 1 t\-� '\\ �_/ � _ "� �, r. _ _ ' � " � -. , '• I Y {� y �..} ' \\, a _ �� \ii ��\1.^ `i �� `,_�� '� a,;�'.��cF`z� . ` •�� \,; � �� r��R ��1 r� � �� -/� n.-..i(�; � �� `� ° � � - � � , "C' `�� y r �,\ � l„ti� - _ t �, '�;.� `�:r �''/( ��\\\ , �� : � � �a i � � � ' �>,\�� - � - r �J +, �.: � �'�. t ' �-� � '� � l - � _ � � { .��- - - - - :,�_, � , `- r.. ,,� .�. 1 Y�. � - � I: � l. \ �C". 7�l f�� I` r`� N_ I i. > _ _ r�, J• � s �� F� �i � .�., ,\ f� r' �`'f �� - `} � ' �� b� �� __�� -`J � � i__ � I �.,.. �: �:, _ �`' o��\ T': ' � '�.� ` �-`� �' �� '��rrr � �?S % - � _ � � ��' ��' r"1+�� - ' - - � — � L� `' �`�.J '`- �M�''��j,�-r� � ��=v. ,\�: �r- - � _ '�-: L- �i,�_�._,..'�G:T- . . � _ ,� _ _-_ � _ � � � l � ` ' :,�` i . -. . , -� 1 :.. �-�- \�\ \ ,` �-�� /� �� y _ ��«. .\ .- \\\� '' -i -""Y=`/..r I Jl �I,, `�. \�� 1ul �' -�,:��'r�-�� : - . {/��4t� ��. � � �';�� ;t J , �', k ,� —r-' , 3 '" � z'�". , -., ti t, �' l 1. r l r ��j ` ? ��. r ° � �� `U � ` � '.} �1� � �F :_,-�I�'/?I�7 �';�� , 4' � _ �'�� /� - '� - _ 't:�,•' .y ` _�: � ' �; :- � n � : ` \\ y. �a��` 1 �� t�. t .J ;� � -;l'� ��` G�: � � :.��f�' �.,r - � ., �: \� ��- _- '�., �� !=��r � � � ��T � _ _' � � � -. '� , �� _i,, � k � � ' ` l �" �C'-,.� ';� � �-� t, � �� t.= �� • � \ . i v�i �. �.Y ' ' �.` y- _ - - �� =� � ��, �.�i '^� L1 � .1 ;' \� � �.�� \� = �� - �� '`�' i` t.�? �.1 � �-- � ,� t I ti -" ;'. -'ti _ �:: E. � \ ; _ - _ = ��/ '�' �;�� h.. '�• ,, r � , � f � -t � r S f�' s's--t-z}� � . f , ' � _-ti '� � � .� 3 �,c G'_ :: .� � _ � � �� ^"��fr'�.�."� .d--� ' . � _ � '�'� - — \, � - :x .J'. I I f ��r "�`-*r�'�si' �s. , �� q. � d.d- \` ---� �- , ,.: .l� -�i .� n k. _/ I � )�. . � . I. � i'. � J � - . (�. i. � J �� j _ _ �. ' � ^ � ,l ��': " __ , �. I _ .T. �L-� . . - - � 1 � C � ( ' �; \ _ � Y J , �T� X"`a .�` : .\ �,��Y \ � f `` I / .f �1 1 . . ,� T � C _�/ _ ��_..1J ��..�r. ��} , . -� �--�,� .n„ p ! x , l u ' �2'_.. � I '. _ v.J(�`. �' i,��" �:� ,�=� '� o\: \\ • � , . .i ,�. � �� U�.r-`�r�� 'r3 -t�,� �^' . � _ f - +,�� ; :. - - i-. �-%�. l, - - -�: - ' - _•- I .{� , ~ � r\� �` f . i � �7 1 � _ a' - � 4 2 T ;) _� � " � " �=j , ` �i -�, �= 'l -�� . s—'� ,� I . �' -. _ ..��5 "� y _ ; � ��,� ��__ ( �'�� . � z-.':'.... '�vi � • ��.._ . . . �v v:o*r •�� ••� r .r � �� p � � The boundarfes of the sensitive areas tlis- �has� toal mines haw ha L playecl on these maps are approximate. ��g ��the most rece�K m I i i � J Additio�al sensitive areas that have not th• Washington Depa►tme� been mapped may be present on a devel- sourcas. Any devsloprr MILE � opment proposal site. Where dffferences adjatent to these arsis sh� occur between what is illustratetl on these by a thdouglf study to Co� maps antl the site conditlons,the actual pre- existente of additlonal su sence or absence on the site of the sensitive area - as def(netl In the Sensl.tive Area � Ordinance•Is the legal control. � COAL MINE HAZARD AREAS . SOURCE: SENSITIVE AREA MAP FOLIO, KM1G COUNTY, WA - 1990 �, � r �-_ - . . . x-- � . _ '� 'f S..w�.' .\ 1 ,r: _ .:r../� - :� - ��ov Prn. _ : •� �� f '� � - y _ '.;:"��, �+__ 4�M. L � _ -� � _ �� fi � _��w �� ' �� ;h :�� ' = � �� - Jk=�_ \ ,�. , � ' . I � t,� y� �}s''�� '�,\v��:� \'ll'I �.. _ � >��t• �., l' � � lh .,_C� C�l �:_ �� `� '�j �1--. l r �f� Il �.� � \ \�^�`" ��'� 4 � .� ��.. ��-S �}... � -�� .' ` { ✓:� r \ ! _ c ` � �� a _` � ��\� \ ,�:� � _ �a ' , , � � � r � � , � �� •v�� ,� � -^+ � �,� y. � , c �' -`�� ' \ ^ � � � �` ��„__. ? � � � r < ; ,; ' .�-:o �i :� ..� -,, `� � " + � '`�^ ' � -. �'''--�'�� 1�z- �i'.. �,_. ��r, hi � rwn' '�.,t-•-�, ��i�� ' i =� ; ' `4- . �i� � . �\ �. +� ,.�, �b,�- � � �„z,� ��1 �'. � y l � f�� ¢ �l�. k,.y� _ - . I �, ( � i ,�;, r�^.� _ i � �' � �'��.�.�� \\, ��'�� .=� � / i J �� \_ _I 1 � 1 ( �� 1�. �\ �� -s �4 .{ 1 \1 � � .� 4 i I\ . .. - � �' - � - l � ,; �, '' � r ' �� z '# F ' � ��,�} �i :� � `� ' r � - - �� :�J�: � �� '- - t _-...\�� - -�r � . ` _ , , ♦ Y '�,� i t '\ ` .. .c � , . - .. i ti S�. r � � . I ' . '. �. ' �� r � I 1 . , f 4- I � � \ f _� . .�� r� _r �- �1� � ` \ � � �,� � � >� , ��,�=<. _ i . � � ;`� ` ''� _ � ,� ��'� � � �.�� +�.� _ _ f \ :.�� . )�" '``� :�, ` / ; ,.(�� , � �� \1,\'KSi:,.�- - _ _ ' �I I �� . j � / . � .'� 'r ( � . 4 . � _ .� .:� � �r\yL 1 ��f �..�� T � ;„ �� _ .��`'� ��'-'�� ,. ` ''�- �� ''� j�� _'`',� -fz ,�-•, 1��T ,� .�✓�- � �. r � �, �� , I � � ' �� T� - � - J �I . � �'- � .\�_ /�'t y �� a `'� h � � S, � �� a �-�;f ��°� - ��"' � -� �- - �' � � � >. "3 7 z , i � +;� � .� �/ �; f ��' � 'i E. I t. `�� . �:. � �( -iF �i ��'��' •,y� � G �', -} i l l . I (((�� \ � ' �vr / � j'g,.1"" o - �i' 'Y ��,'� � '� '�`�6\q :'_i� /� �'.� - _ �$-`' : - ' '� 'i= �. �.- �`c�� . �� . �f r / , ,> �5'"- _ 9 = _ _ .\' ,\ � � ��.1' } �:�F.�!' �r _ ,�,a� - -� `'" •\ -.�+� `./ ��: E � Y � � � `� � � � � �' - " .�� > � � ��,,� a, ' a , � � . ` �\� .. � � ,� � - ' �-a7I!�` ' t�' , v_., ,�`�� \\ . \�� _. 'r �, - ",t� I'• -� j � � .^�' � - ��`'-� �^� -'�.� I `�., �� :� � '�� ' _ - _ ` • :: � �3 � y.. l� �' � \ ' �` \ ._ _ _� ��. 1` ir �� \'�� .� � � r \ � i � � � ` .�-�, � `_, � r - '1V Ea� � � y� r-� +� � � �, ��1i �\- �,1 � ,�r� �� -__ �� . \ �` _ t�'� \�� _ F J � �� I °� ,� _ �� \ \` .:•� \ �� ,', \ � � / \` yl} a}' 3i� � �F� �. .�"� �;` � `��''-z y. � . • � , < `` �•.' r,•� ,�'. i � r�. 4� ,s : " . ': v. i �. �' �'� ` •— __ - '� -�'^ �,� �' `.i; ' I� i •: �r.~ ` 1 ``�.�, � I - , - , � `'s^ . :'� -\�,; �' 9 _\'. iZ 7:� �` '�_\ '�:� .1. � lL' �� 1 A : ._"' ; • - .� .. Y _ ��y � � - ` �{ �Y �^, ^ �� _` � �'.� � 7 , 3 .�.� �, ��-�-a �.� � � ��. ��t .'11,y J - , 1 f � G ., fi•' 'F�-• . _. . ` _ ' ' �..1 I � y.�" . : . : ,_ _.�`✓ `TT'�J'�� _ • = C/�` i .t `s1 ��ti I� �`.s� � ��T.. ' ,� r l� '� '�.! �fn t / #i L��5 _ 1�" 1 '� � \ 1"`-t �� I i. �S . � .- .i-�.�� 1 � _ � \l � _ � ( -. _"��/^� 1 i � �` . _ J � x. � ^C / '.�' �� ^�4 �-. i�z '�_i 1 -\ - --.-� ��' � . ..� . ' . �� • i ✓'�.� ��^-� 7`1 . 1� ,'�h ' - — - ' 1 Jr. ../�.' xc,.f�,-: yF...,,+ �.-� +1e, \V I { ' '��'M" _ _ .' L�: �. I;. !� !- 1 ��,!- '_ � � _ ' "i I :A '�. ,�_. �\.� _ ' _ a � c'" � _. .. . . _ '• � L ' ... � i � d�. . , • �'• � I � C�..�lts�- . J�� _ � `_ :, . � � �` � ` •' \ `�, �,�.5 .� �i , s�-'- �� C �' _. .\ .{t _ ,.. �f �\ � , I I '�. �. � y 1 - t��t !• ._' c. t . .a_: _ (�: . � . � . ' t " ��.. �� ,_� ,. ��, `i . ., �- �'�� _ �Tr.� ` . "� :.�„ � .� \� �. ' ,.}�'� � ,"� '�!./.� �� I I �� . ' ..� { v : •yy ^ .. '.:� -..� ..� " `� ' � . . - � . : - � io V1m��e r rr � ��2 0 ` � The boundar(es of the sensitive areas dis- See wEtlands and lantlslide I played on these maps are approximate. atltlitional potential seismi i Additio�al sensitfve areas that have not Wetlands and landsllde area: 1 1 I � been mapped maY be present on a tlevel- to failure during earthquake MILE � opment proposal site. Where ditferences hazard areas not shown o I occur between what is illustrated on these shorellnes untlerlafn by lacu: maps and the site conditions,the actual pre- these are susceptible to IiquE I sence or absence on the site of the sensitive SEISMIC HAZARD AREAS dfea _ as definetl in the Sensitive Area Ordinance•is the legal control. � SOURCE: SEN5ITIVE AREA MAP FOLIO, KING COUNTY, WA - 7990 Appendix B Proposed May Creek Basin Action Plan Basin Maps � � �— �.j� � , Figure 2-1 :111,t1�G!�y�y � � I Ji'� 'V�:' L_.r_� � � ��r ; : ,________ , �______ _, Water Features/Subareas Map r�dr �;r+;� . ~ � `---� I ��:,,,►,,,,,�,,,� �� ,� ,►_,, �� -_ May Creek Basin � , NEWCASTIE �� ;� 't-_� �:� aq + 'i+ I-- , ,� , ` ��, r �o � � '� � � I �RC��)f��L �"�� 1 B •�16 � � K � � Lnkr ,� )sv `;yF.n. /` .L_ � Onrcr� t t 47 Ch� �' � � `:k� .� � -��' 07 nn a� i .. �G�� J1 ; i s �4� 8„ �� ej �<,rrrk ��1 � �, /��F '��= � � '� O� � , � ;,.�� >'I .9 z �� S� �,,evo -------.� ii a� . . 1 . J4.�:.{ 42 r� �.. � ♦ �� , r�'�.`� '� "c . � I � �� t , ; �M � � ♦ � � : �/ u, ' '.�� \_^.. . '::c �o,°r�,�^' � 0 1A �-,� ° o7eo �� . 1�� : ,�75 i C�6 12 e .. 14 ''o'. �, SS`�..1 i �n j I1 sY t�� ` ',�Fye o'C•°�f ' � 2eb v � HIC�HLANDS °N�}�j, '£ ,$ �?° � ao � � — f'�. 1 ..,,r, �02° �nrrq i�` � u � a9 � ' 45 ��, �}��_ o�y 1 `� i ;�r4 �'',, , ; � ' _- � � o ,� ---- �� ti°' , � , y�; LOW�1!" � �� '� °r . '� '�� ! {� �'s I �6 BASIN � '�r 1 , 1 �"� �1 �', �� d ' ' Q�__ Id � `t ��` .`„'� ,o *�t. �� •� o�+,� « �> —��-�--� r �♦ "i,,.�65is' 6e �`,� � � c, n� .'!�;;4. MM � -L--- , � k y ,:..v c � � v�r� i � ,� �9 ":F u� . 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PROJECT SITE �a �� o� N �e y � � �' 1 N ../� Basin Boundary 76 .��• Subarea Boundary °�`�� 10: f $fream 8�Sfream Number ��k` �K�nldi•vu `� lake p i�2 � Mue � so i__.0 Wetland&Wetland Number -_I Incorporated Areas Ocfober 1998 SOURCE.•Proposed May Creek BasM Action Plan, AprN, 2001 981U 2-1WaterFwlurcs-SubAreas WG —� � . i � � Figure E-3 � � ,,<<� � � � � '� � �° � East Renton Plateau u �ol1eY Q\� \1,� ,+�a.... �� ""~ � � \,��"� Conditions ' f�rr. / � t i �zg? � 'N i `'• ��__- May Creek Basin rr� i- \ a � � • � � r I �` �jl:�� -.__ lud/n�i A1,. 81, n . �•- � -� �R/t J �+ IIA.A i D � = ,m "� 0?9� �� . z L�f 2 , �.T �1_ � O I N � ' I �� " ry e �a ` 0 0 "' � _ _ n O ' � `� o �� ` ^ r� •�f e � ` N �14 Q `` , .\ ` I� ` � /�, o �a' �, i i 6�CCll� � ' •'y /��nn¢�, �. � ` _r 7 a a f+� � / � ' � \ p f � ^Y L� �� / _ O � m � - �f � t` � a . a � . ` M' _ _ - . � o � - _.. Y �olloy R`� _ _ __ ♦ ' �WM< a , -_- _ _ __ - _ _ - ! _'_ _ ' �: O i � .�� _ -- - -- -- - � '9� O �. ' ' ' _ ' ' � -1 a� i � -0 I� �� _ _ -= _--� � I � � � � �,� ___--,,- -: __ \ o~ 1 � x �•�- - _ , ow/ i � � i.�� p _ , �� rl: (� � ' � --_ _ —�.��,,v;% _ `I - O � ` b In _ ' � ��'�� v ' � �� c 'v�� ,.� ,. "�� Basin Boundary i � '\� �—� . � 'c' !� .,i"� Subarea Boundary j � � = o1N< o�qq ' SL I'��h ST ,� �- Stream&S►ream Number � L6 �i -�.� a• `� �ake PROJECT SI TE ""�`� o ^T o �'� Wetland . �, N .�r Concentrated Spawning Area �t �{ QO /� Problem Area . � ^ � O Locally Significant Resource Area ' '_ • , `� N � Wetland Habitat Problem - � Stream Habitot Problem � �� + � ^ � Erosion Problem t�' r 0 1l2 1 Mile L��kc � Flooding Pro6lem `KnNdet•n � $ediment Deposition Problem Oclober 1998 ' SOURCE:Proposed May Creek Basln Action Plan, Aprll� �OO� 9810E-3 Easl Reoton ConA W(