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HomeMy WebLinkAboutSWP272730(2) r r PRELIMINARY PLAT OF WHISPERING PINES 1 ' PRELIMINARY ENGINEERING DESIGN REPORT AND ' PRELIMINARY - STORM DRAINAGE T.I.R. 1 . ' Prepared for: Nancy Bennett 1 lumber: BNNT-01-WSPN 1 1 ' Prepared by: The O.L.D.S. Group 4620 200' Street Southwest, Suite F Lynnwood, WA 98036 ' (206) 712-9688 ov O 0 "P 18093 ry` `A ��•IS701 EY,PI ES /6/ t JULY, 1997 SEP 1 °1 1997 DEVELOPMENT PLANNING ' CITY OF RENTON ' TABLE OF CONTENTS ' ITEM PAGE ' I. Project Overview TIR Worksheet 1 Location 2 ' Existing Site Conditions 2 Proposed Development 2 Site Development 3 ' Utilities 4 Vicinity Map 5 II. Preliminary Conditions Summary Basin Analysis Existing Basin 6 Developed Sub-basins 6 Soils 6 King County SCS Map 7 1 III. Offsite Analysis ' East Basin Offsite Analysis (Exhibit II) 8 West Basin 8 West Basin Offsite Route Map 9 IV. Retention/Detention Analysis Special Requirements Analysis 10-11 ' Existing Site Hydrology 11 East Basin 11 West Basin 12 Developed Site Hydrology East Basin 12 West Basin 12 ' Hydrologic Analysis 12 Retention/Detention System Analysis 13 ' Existing Basin Analysis East Basin 13 West Basin 14 ' Detention System Design 14 Developed Sub-basin Analysis West Basin 14 ' East Basin 15 V. Conveyance System Analysis 15 t t TABLE OF CONTENTS ' ITEM PAGE ' VI. Special Reports and Studies 15 VII. Basin and Community Plan Areas 15 ' Not Applicable for Preliminary Plat ' VIII. Other Permits 16 IX. Temporary Erosion and Sedimentation Control Analysis 16 X. Bond Quantity Worksheet 16 ' Retention/Detention Facility Summary Sheet and Declaration of Covenant XI. Maintenance and Operations Manual 16 ' APPENDIX: ' Storm Drainage Calculations Natural Basin Discharges Developed Sub-basin Discharges ' East Basin Detention Model Program Storage and Discharge Structures East Basin Detention Model Results ' East Basin.Detention Model Results w/Residence Infiltration. Exhibit I-A - Natural Basin Map For Area ' I-B - Site Existing Basin Map Exhibit II- Downstream Analysis by Lance Y.K. Gyotoku,P.E. Exhibit III-Developed Sub-Basin Map 1 1 1 1 1 1 1 1 1 1 1 1 King County Building and Land Development Division Page 2 of 2 TECHNICAL INFORMATION REPORT (TIR) WORKSHEET DEVELOPMENTPARTS • is ' REFERENCE LIMITATION/SITE CONSTRAINT G' Ch.4-Downstream Analysis oNE 0 0 0 Additional Sheets Attatched tPART 9 ESC REQUIREMENTS MINIMUM ESC REQUIREMENTS MINIMUM ESC REQUIREMENTS ' DURING CONSTRUCTION FOLLOWING CONSTRUCTION ® Sedimentation Facilities 0 Stabilize Exposed Surface [ Stabilized Construction Entrance E::] Remove and Restore Temporary ESC Facilities ' Perimeter Runoff Control F__j Clean and Remove All Silt and Debris C] Clearing and Grading Restrictions 0 Ensure Operation of Permanent Facilities E:] Cover Practices EJ Flag Limits of NGPES ' t-?K Construction Sequence 0 Other Other PART 10 SURFACE WATER SYSTEM Grass Lined Channel Tank Infiltration Method of Analysis ' ® Pipe System ®. Vault(v,/E—r) Depression S C.S T—A Open Channel Energy Dissapator Flow Dispersal Compensation/Mitigation O Dry Pond ED Wetland Waiver of Eliminateo Site Storage ' FI Wet Pond 0 Stream 0 Regional Detention Brief Description of System Operation We5T 5u a ;;AS7/n/ P:Lz w Zt-Lj_�s ' Facility Related Site Limitations Additional Sheets Attatched Reference Facility Umitation specialPART 11 STRUCTURAL ANALYSIS PART 12 EASEMENTSITRACTS (May require [� Drainage Easement ' CO Cast in Place Vault Other Access Easement 0 Retaining Wall Native Growth Protection Easement ED Rockery>4'High Tract ' Structural on Steep Slope 5_Q Other sLoPL-_ PART 14,SIGNATURE OF - • • ' 1 or a civil engineer under my supervision have visited the site. Actual site conditions as observed were incorporated into this worksheet and theAL C attatchments. To the best of my knowledge the information provided &Jy �— ' here is accurate. S'° '�Di' 6 Pagel of 2 ' King County Building and Land Development Division TECHNICAL INFORMATION REPORT (TIR) WORKSHEET ' PART 1 - • • -. LOCATION ' D D • PROJECT Project Owner FANG `tom F. 13c—NNE Project Name /--yAT" 6E V&SP�-gINa f�7m&S Address Z(o 12 s AVCAZUE l'I• E. Location , Phone VZ5— Z 55— /5`f0 Township Z 3 N Range Project Engineer Ro a r 0 LoMN�LL �R• lz` 5 Section NE 5 ' Company l NE O•L•b�. Q O c1 P Project Size Z.7 2 AC Address Phone <fZS--7/ Upstream Drainage Basin Size o OAC PART 3 TYPE • • OTHER PERMITS ' [�D Subdivision 0 DOF/G HPA Shoreline Management ' F� Short Subdivision COE 404 Rockery El Grading E:1 DOE Dam Safety Structural Vaults = Commercial 0 FEMA Floodplain Other t © Other �Fke5 L I M I N A 2 Y PLAT 0 COE Wetlands E�l HPA DRAINAGEPARTS SIITE COMMUNITY AND Community ' C:r 7`Y O r ,P'/VTO Drainage Basin C5 2 Zvc2 MAC,- 0 River E-1 Floodplain [� Stream ® Wetlands 0• 5 9 �G• G4-i4SS ZE E:] Critical Stream Reach 0 Seeps/Springs ' Depressions/Swales High Groundwater Table Lake Groundwater Recharge t Steep Slopes Other Lakeside/Erosion Hazard PART 7 SOILS Soil Type Slopes Erosion Potential Erosive Velocities r Additional Sheet� sAttatched 1 ' 1 ' PRELIMINARY - STORM DRAINAGE (TIR) PROJECT OVERVIEW ' LOCATION - The Whispering Pines Plat is a 2.79 acre parcel of land, which lies in the Northwest Quarter of the Northeast Quarter of Section 5, Township 23 North, Range 5 East W.M., and is addressed between 2612 and 2616 Jones Avenue NE, in the City of Renton. The ' property accesses Jones Avenue Northeast via a one hundred-fourteen foot long and fifty foot wide right of way dedication, which is approximately 105 feet north of the plat location of Northeast 26 Street. The dedication continues another three hundred-eighty six feet to a 50 foot ' radius cul d sac. The main body of the property is dimensioned 517 feet west to east and 223 feet north to south. EXISTING CONDITIONS - The southwestern portion of the 2.79 acres has been used as a shop, storage and vehicle parking area, with slopes of less than three percent. The north half of the site is pasture for two horses,with slopes of two to six percent. The northeast 0.60 of the site ' is a proposed NGPE for wetlands and associated 50 foot buffer, with slopes of thirty to sixty percent in the buffer area and slopes of 20% to flat in the wetland area. The remainder of the south half of the site is a pasture/storage area, with slopes of one to five percent to the toe of the fifty percent slope that drops from the neighboring plat of Sunset Hills to the south. The site ' topography is shown on sheets 2, 3 and 4 of the attached preliminary plat set. As the site topography shows there is no offsite contributions of storm water to the uplands area of the proposed Plat of Whispering Pines. Storm water does flow from the residential properties east ' and southeast of the site into the wetlands area in the northeast corner of the property. Exhibit I-B shows the existing site natural drainage basin lines. Approximately 0.68 acres of the ' site discharges to the west, of which 0.17 acres is impervious asphalt driveway, gravel parking area and shop building roof. The east 2.11 acres is split between a proposed 0.59 acre NGPE for a wetland and 50 foot buffer and the remaining 1.52 acres of the site which is all pervious ' pasture and meadow area. The surficial soils are shown as an Indianola type on the USDA SCS mapping for King County, see Page 5. ' PROPOSED DEVELOPMENT - The applicant proposes the development of 10 single family lots meeting the requirements of R-8, minimum 5,500 SF lot average, zoning. The proposal includes construction of 500 LF of 32 foot wide street and a 50 foot radius cul d sac, with t curb/gutter and sidewalk. The 0.60 acre right of way dedication is being proposed in accordance with City of Renton development conditions and requirements. ' Site Development - There will be no general site grading. The lot topography will remain substantially intact except for slope grading for the street construction. Grading for the street will drain lot and street storm waters both east and west in accordance with existing basin discharge requirements. During street construction water, sewer, gas, electricity and telephone utilities will be extended from Jones Avenue Northeast to serve the individual lots. Except for the storm vault construction and sewer utility trenches all grading and construction will be within ' three feet of the existing ground surface. The street will be paved with curb and gutter, sidewalk and street tree planting strip. The wetland will be flagged and fenced along the outer limit of its buffer during construction to minimize intrusion into the sensitive areas. Prior to final t 2 ' acceptance by the City of Renton the proponent shall prepare and record a Native Growth Protection Easement for the wetlands and its buffer. No other mitigation is required. ' Utilities - The following provide public and franchise utility services for this area of the City of Renton. ' Public utility provider: City of Renton (Water, Sewer,Refuse, 200 Mill Avenue South and Storm Water) Renton, WA 98055 ' (253)235-2520 Telephone provider: USWest ' PO Box 12480 Seattle, WA 98111 (800)244-1111 ' Electricity/Gas provider: Puget Sound Energy 319 South Third Street ' Renton,WA 98055 (253)382-7858 The Kennydale Sewer district will have a fifteen foot (15') easement along the outside of the wetlands buffer going from the east line of the plat to the north line of the plat crossing Lots 6 and 7. 1 3 1 in _ felts i:o 11la y � i. I z q oro NE ' Av kV $ kAtiTf1 �M1s Ay �� ,r� 4 t� pvt 21" f prp AV r rPRELIMINARY CONDITIONS SUMMARY ]BASIN ANALYSIS: ]Existing Basin - The proposed development contributes storm water runoff to two basins, the I�edar River and May Creek, Drainage Basins, as shown in Appendix Exhibit 1-A. It is the intent of the plat design to continue the contributions to both basins. r ks described in the introduction to this report the site uplands do not act as a collector of off-site drainage flows. As the topography shows the areas south of this proposal are graded to flow south, the areas to the north flow to the north and east, the west is above Jones Avenue and the ' eastern portion of the site can get flows from only the west. Storm water flows do enter the wetland, a portion of which is located in the northeast portion of site property, from residential areas to the east and southeast of the site. ]Proposed Sub-Basins - By reducing the developed contribution area flowing west into the Cedar River Drainage Basin the developed site will direct discharge the 2 year, the 10 year and the 100 year design storm events at the same volumes as existing conditions. The west basin will shrink from 0.68 acres of mixed pervious/impervious- area to 0.36 acres of mixed pervious/impervious area.)The storm water from the west part of the site will not be collected, lint wifl sheet flow into the new street gutter for discharge into the storm system in Jones Avenue Northeast, which drains south and west into the Cedar River. The point of discharge is at the same point as existing conditions. ' the east basin which drains into the May Creek Drainage Basin will have an larger developed contribution area (existing 2.11 acres, developed 2.43 acres), a combined water quantity/quality r mitigation vault, controlled release for the 2 year, the 10 year and 100 year developed conditions design storms, to the following respective discharge requirements, '/2 the two year, the 10 year and the 100 year pre-developed release rates. A discussion of discharge requirements occurs in r the Retention/Detention Analysis section under the review of Special Requirement No. 1. Drainage from lot structures, driveways and lawn areas on the east part of the site is assumed to glow into the catch basins of the new street by tight line or sheet flow for collection and conveyance. The spreader trench will discharge the east portion of the site at the same location as existing conditions. ]3xhibits I-B and III show the existing and proposed site drainage basin areas respectively. The ' exhibits show the overland flow times and distance for existing conditions to point of discharge. Total pre-development and post development discharge flows will be noted for the 2, 10 and 100 year design storms and designed release rates. rSOILS: The site soils are shown as an Indianola Horizon on the King County SCS Map, see Figure 2, next page. This classification has been confirmed by the soils analysis provided in the ' geotechnical report by Earth Consultants. The Indianola Horizon is typified by deep sandy and gravelly loamy soils and high permeability rates. The horizon is similar to and include pockets of Everett Horizon soils. It is listed as a hydrologic Type A soil in the King County Surface Water Design Manual. 1 5 1 -- •� �• r. EEC, � � y9 '`- '��• t� �� r • - v _ _ _ --__ --- jai ____ -___ ___-. _ _ _ .-•. N o �,f I Q .,; t t�' �100'',1`. ,l.. N; ��• t iM•►i• C� �l�- •�•M LIL �t irk P�0 •'+.k��{+• '�°ry"_�/ I >, I � �i41 �, •'i. � �/��M=�,.� , _ ���7� , r�;1., a v •.� i ��U ♦ 'F, � �-_ .� i'/_. �:..`6 'tdf �,N x � � • , • , '� CJ Q � ,"1�•!�" t� rfi� tc � � '� + ~t 1�' � _ '� I � !k ._ pro IG ,� �^r 7i' 1 i IF•'.. I E IL a' cd 12 I' ice■ ��, m r�e:•+- a — 1 � e CAI "�:. � I • .1:,� •C ., •� 1 ..i1Jp1ffi''Y/6.^Y7Pf1,�`,i`° 1 _I�-.T J�r'mlMrr, + .K OFFSITE ANALYSIS ' DOWNSTREAM ANALYSIS: East Basin - The east basin downstream analysis was performed by Lance Y.K. Gyotoku, P.E. ' and is included as Appendix Exhibit H. The review by the O.L.D.S. Group found the report to complete and consistent with our observations. ' West Basin - Storm waters from the west 0.68 acres of the site currently sheet flow from the lawn and pasture, and driveway areas westward onto Jones Avenue Northeast. From there the storm water flows: ' 0 to 240' South along the street east curb and shoulder of Jones Avenue to a catch basin/inlet in the shoulder. ' 240' to 600' South from the catch basin/inlet in an 8"concrete pipe to an outlet in a ditch on east margin of Jones Avenue. t600' to 700' South in a 1' deep by 1.25' wide ditch that flows down to a catch basin/inlet off the shoulder of the intersection of Jones Avenue and Northeast 24 Street. ' 700' to 750' West from the catch basin/inlet in an 8"PVC pipe to a Type II drainage control structure on the west curb line of Jones Avenue north of Northeast 246, St. ' 750' to 970' West from the drainage control structure fifty feet to another Type II locked structure. Continuing west for another one hundred sixty feet to another Type II ' locked structure from which an 18"PVC pipe discharges to the north. 910' to 1,560' North in an unnamed creek, which measured 2.5' to 4' on the bottom, and 4' to ' 6' across the top of a 1.5'to 3' deep channel. 1,560' Creek channel enters a large bore pipe for conveyance west under I-405. ' See next page for flow routing map and stationing. 1 1 (gym? 7 1 ' WEST BASIN OFFSITE ROUTING MAP ( I — ;11 '' /6 dos :7s r�.+ -p�•,.-/��„I i►K _ ? 'r •� ' I ]33I�to /10 ✓t I, 1 `, IN li: Immo N.F. Z 270 27.9 - 0p 278 Z w r T� 2619 - _ [t��E • S7AQY O _ f� Tlie . JI — '� (Dl rsc (C) Iro II ,li rr•.�' i iS1 3( - 67. 1 lr 7�t ' srtN�E8TI 28 -io, c.B/ 2 I 2 so 295 v L�GENIU blow IaaT PATH LF � (? IIg e g 2 11 _ I ' 1SI I z. 10-cr— — i ' cc) I U L��7- c <- r�i;� • rt . 3s I7 96 N E 24 TH PC 1 12 3 i ,I V_I �� 1f � ���� ' ., O -l.i4c1 • O6 J^ �I I g GROUP 8 r ' RETENTION/DETENTION ANALYSIS ' REVIEW OF SPECIAL REQUIREMENTS: ' The City of Renton requires development to meet the standards and requirements of the 1990 King County Surface Water Drainage Manual, which includes seven (7) Core requirements that must be met, and twelve(12) Special Requirements that must be addressed and mitigated as they ' apply to the development. The following addresses the Special Requirements providing possible mitigation measures for ' those that apply to the proposed project. 1. Critical Drainage Area - The site does lie within the designated May Creek Critical ' Drainage Area, as shown in Exhibit I-A, a portion of the Cedar River Drainage Basin. Approximately 2.43 acres of the proposed development drainage, eighty-seven percent of the sire, is received by May Creek approximately three-eighths of a mile downstream of the proposed Plat of Whispering Pines. After reviewing the King County Public Rules for the May Creek Critical Drainage Area, Policy 6.4 requiring restricted controlled release from the site water quantity/quality mitigation vault. The standard requires '/2 of the two year pre- development release through the 2 year developed design storm, the 2 year pre-development release through the 10 year developed design storm, and the 10 year pre-development release through the 100 year developed design storm. Comment - The City o:B�othell sadopted neither the 1995 Edition of the King County Surface Water Design Man the May Creek Critical Drainage Basin. King County Cohn Surface Water Management has drafted a new May Creek Basin Plan, which is going through final ' review and approval by all effected jurisdictions, including the City of Renton. In lieu of the current King County policies and the Draft May Creek Basin Plan, the City of Renton has allowed retention/detention design in accordance with the standard/normal requirements of ' controlled release for '/2 the two year, 10 year and 100 year pre-development flows. The Draft May Creek Basin Plan currently allows discharge in accordance with the release rates used by th,. City of Renton. The city has also allowed use of the standard release if the downstream analysis shows that the channels and conveyances are stable and show no signs or erosion or over capacity, which the analysis for the east discharge by Lance UY.K. Gyotoku, PE, see Appendix Exhibit II. Policies 6.5 through 6.11 are for process elements that will be complied with during design and re,riew of the final project plans. Specific elements of some of the policies are addressed below. Policy 6.6 - Review of the site by the O.L.D.S. Group and Earth Consultants, a geotechnical firm, have found no evidence of either topographical or geotechnical features that would require a phased installation of the proposed storm water quantity/quality mitigation system. Should it be required, a phased plan would be prepared as part of the construction permit submittal. ' Policy 6.7 - The design does include a flow spreader to discharge the controlled release from the detention system. It is placed at the toe of the slope, with a discharge surface approximately twc)feet above the wetland water level. 1 cGR®UHD 9 Policy 6.8 - This site is in an urban not a rural setting. Policy 6.9 - Clearing for this proposal shall be limited to the right of way area and a single crossing of the wetland buffer area to construct the outlet pipe and flow spreader, approximately 2_1%of the site area. ' Special Requirements No. 2, 3, 4, 6, 7, and 8 - These do not apply as they are for conditions not found on or proposed for this site. ' 5. Special Water Quality Controls - A wet vault is proposed as part of the site storm drainage system to mitigate special water quality requirements for the point of discharge ' being a critical area, wetland. 9. 100 Year Floodplain Delineation - The nearest 100 year flood plain is approximately 200 ' feet below the site in the Cedar River, a half mile away. W. Flood Protection for Type 1 and 2 Streams -This does not apply as there are no Type 1 or ' 2 streams on or adjacent to proposed project. 11. Geotechnical Analysis and Report - Is provided per requirements by Earth Consultants. ' 12. Soils Analysis Report - This is not required as the geotechnical report found soils consistent with SCS mapping. ' EXISTING SITE HYDROLOGY: The existing site natural basins are shown on Appendix Exhibit I-B, while the developed sub- basins are shown on Appendix Exhibit III. Modeling of existing site basins was competed in ac-,ordance with King County Surface Water Design Manual requirements. The proposed conveyance system was used in the modeling of the detention system requirements for this ' preliminary report, though final design may alter the storm layout. The conveyance system when designed for permit submittal will most likely make very small reductions in the detention volumes. ' E<<st Basin - The east 2.11 acres, including the 0.59 acres of wetland and buffer, contributes to the May Creek Drainage Basin. The uplands portion of the site contains 0.02 acres of impervious area in the form of a workshop/garage and adjacent concrete pad areas with the remainder, with the remaining 1.50 acres of uplands area being meadow grasses or horse pasture. Storm water from these areas flow across the grassy surfaces with slopes of 1% to 6% to the . ; G3!,-: edge of steep slope dropping into the wetland in the northeast corner of the property. The slopes into the wetland vary from 15% to 66% and show some areas of instability. All flows are sheet flow in this area including over the steep slopes, which are generally well vegetated. The site ' so1s are of a hydrologic Type A, very permeable and stable. Pervious and impervious runoff curve numbers of 65 and 98 respectively were used to calculate flows for the existing conditions. ' Our investigation of the site found no offsite areas contributing storm water flows or discharge to the upland areas of this portion of the site. The wetlands do receive flows from residential areas to the east and southeast of the site via contiguous areas of wetland adjacent to the northeast ' comer of Whispering Pines site. ' = � D (SIR®� 10 o 0 0 0 West Basin - Storm waters from the west 0.68 acres of the site currently sheet flow from the ' lawn and pasture, and driveway areas westward onto Jones Avenue Northeast. A small area, approximately 250 SF from the lawn of a residence to the north of the proposed development flows onto this portion of the site. The volumes of the offsite flow contribution are inconsequential for this analysis. The same CN curve numbers used for the east basin 65 and 98 for pervious and impervious areas respectively, same hydrologic Type A soil horizon, were used to model discharge volumes for this portion of the site. The west basin had 0.14 acres of ' impervious area in the form of paved and graveled driveways, and 0.54 acres of meadow and lawn pervious area. DEVELOPED SITE HYDROLOGY: East Basin - The site has been designed to accept runoff from all pervious and impervious ' surfaces from the 10 proposed lots and the street right of way east of station 1+80, except for the exist 20 feet of Lot 5 and the north 15 feet of Lot 6,which will bypass the collection system. The bypass areas are now and are planned to be pervious areas, either lawn or landscaping. Total sub-basin area will be 1.84 acres, with 0.87 acres of pervious area and 0.97 acres of impervious area at maximum coverage allowed by City of Renton Zoning Code. CN values were derived from the King County Surface Water Design Manual as 98 for ' impervious and paved surfaces, and 65 for lawn and landscape areas. All roof drains are assumed to be tight lined to the nearest street catch basin. All lot driveways and pervious areas will sheet flow to the street for collection, with the exception of Lots 5 and 6 which may require driveway and yard drains to collect the storm water and convey it to the storm collection system. All drainage from the east basin will be detained and mitigated for water quality using a wet ' vault. The point of discharge will be the wetland in the northeast corner of the site, same as existing conditions. West Basin - By reducing the developed contribution area flowing west into the Cedar River Drainage Basin the developed site will direct discharge the % of the 2 year, the 10 year and the 100 year design storm events at the same volumes as existing conditions, at the same point of discharge. The west basin will shrink from 0.68 acres of mixed pervious/impervious area to 0.36 acres of mostly impervious area. The storm water from the west part of the site will not be collected, but will sheet flow into the new street gutter for discharge into the storm system in ' Janes Avenue Northeast a maximum distance of 180 feet. The 0.36 acre sub-basin will be covered by 0.19 acres of pervious area in the form of landscaping and small portions of lawn ar.-a from lots 1 and 10, while the 0.17 acres of impervious area will be street pavement and sidewalks. The CN values for the west basin are the same as the east basin. HYDROLOGIC ANALYSIS: Based on information from the King County Surface Water Design Manual it was determined that the 24 hour precipitation for this region of the City of Renton would be 2.0 inches for a two year storm, 2.9 inches for a ten year storm and 3.9 inches for a 100 year storm. The CN values far the existing conditions were 65 for pervious and 98 for impervious areas. The CN values for developed conditions are 65 for pervious and 98 for impervious areas. ooa2 (CIIIP3®NIia 11 � o ' There is approximately 0.09 acres of pervious area that will flow directly into the wetlands without being collected, conveyed or detained. This area, when developed, will be lawn and ' 1�ndscape area of nearly the same CN value as the pre-developed site. For simplicity we have included this bypass area in the East Basin modeling. ' We also considered the use of infiltration to mitigate site discharge, but the only application that would be effective is infiltration of residence roof areas. With an allowable percolation rate of 2 4"/hr. to 8.0"/hr., from the King County Surface Water Design Manual Section/Table 4.5.2 and a regional scale factor of 1.0, and tested percolation rates between 20"/hr. and 100"/hr., from site geotechnical report, infiltration is feasible. The O.L.D.S. Group analyzed a total area collection/detention model for the east basin as a more conservative model and the worst case ' condition. The point of discharge for the east and west sub-basins are the same as existing conditions. A ' spreader trench will be used to discharge storm water to the wetlands in the northeast corner of t1.e site as a method of preserving the existing point of discharge. ' RETENTION/DETENTION ANALYSIS: The basis for all analysis and design for the Plat of Whispering Pines is the 1990 Edition of the ' King County Surface Water Design Manual and the City of Renton Zoning and Development Codes. Waterworks by Engenious Systems, 1994 edition, was used to model the system elements and calculate flow and detention volumes. Waterworks allowed us to write complete and comprehensive program models that processes and calculates each of the natural basin and developed sub-basin systems. The vault shall be sized to include a thirty percent(30%) increase in volume as a factor of safety. For the purpose of this analysis time of concentrations were calculated using the ITC and PTC calculators in the Waterworks program. These calculators assume saturated conditions and therefore give very conservative estimates for the storm drainage collection. Conveyance flow ' calculations were performed automatically as part of the program After revisions are made for Preliminary Plat review comments from the City of Renton and preparation of construction/permit drawings the final analysis will include conveyance calculations. EXISTING BASIN DISCHARGE - ' E ast Basin - See the Appendix for Storm Drainage Calculations to view the basin model summary. The data and results of the model are as follows: tItem Area CN TC Volume Pervious 1.50 Acres 65b/ 17.49 Min. ' Impervious 0.02 Acres 98 18.01 Min. Total 1.52 ' 2 Year Discharge 0.02 CFS 10 year Discharge 0.05 CFS 100 Year Discharge 0.17 CFS 12 1 1 West Basin - See the Appendix for Storm Drainage Calculations to view the basin model summary.The data and results of the model are as follows: 1 Item Area CN TC Volume 1 Pervious 0.54 Acres 65 22.11 Min. Impervious 0.14 Acres 98 1.86 Min. Total 0.68 Acres 1 2 Year Discharge 0.06 CFS 10 Year Discharge 0.09 CFS 1 100 Year Discharge 0.16 CFS DETENTION SYSTEM DESIGN - The east basin detention system will use a water quality 1 vault to detain the storm waters and a multiple orifice structure to control the system release. The vault will be constructed in place in accordance with City of Bothell structural engineering n.-quirements. The vault was modeled with dimensions of 30' by 70' with an outlet elevation of 250.50 and a top of structure elevation of 257.50,allowing for 5.0 feet of detained storage. With 1 a 30% factor of safety the vault size will be constructed as 91' by 30 feet. Half of the two year collected volume will be used as dead storage below the outlet elevation. The total 2 year volume collected is 6,406 CF, of which half would be 3.203 CIF requiring an additional 1.50 feet 1 of depth in the vault. The bottom elevation of the vault would then be 249.00. The modeled overflow elevation of the vault is 255.20. See the Appendix for Storm Drainage Calculations to view the basin model summary. The vault is shown on the preliminary plat plans. 1 DEVELOPED SUB-BASIN DISCHARGE - 1 'Vest Sub-basin - As discussed in preceding sections the west sub-basin has been reduced in size so that the developed discharge will match the allowed pre-development discharges. See the Appendix for Storm Drainage Calculations to view the basin model summary. The data and 1 results of the model are as follows: Item Area CN TC Volume 1 Pervious 0.19 Acres 70 16.15 Min Impervious 0.17 Acres 98 0.87 Min. 1 Total 0.36 Acres 2 Year Discharge 0.07 CFS 1 10 Year Discharge 0.10 CFS 100 year Discharge 0.16 CFS 1 1 1 a� GIRoulp 13 1 Fast Sub-Basin - The east sub-basin is assumed to be fully collected and detained. See the Appendix for Storm Drainage Calculations to review the basin model program and results. The data and results of the model are as follows: Item Area CN TC Volume ' Pervious 0.87 Acres 65 ` 12.18 Min. Impervious 0.97 Acres 98 1.38 Min. ' Total 1.84 Acres 2 Year Discharge 0.01 CFS 10 Year Discharge 0.05 CFS 100 Year Discharge 0.17 CFS CONVEYANCE SYSTEM ANALYSIS ' The conveyance system is assumed to be three catch basins and 215 LF of 12" pipe with a slope oil'2%. The slope maybe revised during final design to raise the outlet invert into the vault. Design calculations will be submitted with the permit/construction plans. ' SPECIAL REPORTS AND STUDIES WETLANDS DELINEATION REPORT - A wetlands delineation report has been prepared b1i Sargent Environmental Consulting,dated March 13, 1995. The delineation was flagged in the ' field and the flags located by survey for the preparation of the topographic survey drawing in the plan set. ' GEOTECIINICAL REPORT - A geotechnical report has been prepared by Earth Consultants, Inc., dated March 22, 1997. The geotechnical report information covers storm drainage issues including the possibility of infiltration. BASIN AND COMMUNITY PLAN AREAS COMMUNITY PLAN - The Plat of Whispering Pines is subject to the zoning and development requirements of the City of Renton only. BASIN PLAN - The City of Renton is currently reviewing the proposed May Creek Basin Plan, which will replace the May Creek Critical Drainage Basin Policies. The May Creek ' Critical Drainage Basin Policies were discussed in the Special Requirements Section of the Retention/Detention Analysis and Design. The Draft May Creek Basin Plan would revise Retention/Detention requirements to the standard '/2 of the two year, the 10 year, the 100 year ' pr,-,-developed storm water release rates for the developed site. ZPIHHII� �o�o�o�o C�IP3®N� 14 ' OTHER PERMITS ' NVOT APPLICABLE to the Preliminary Plat review process. ' TEMPORARY EROSION AND SEDIMENTATION CONTROL ANALYSIS AND DESIGN NOT APPLICABLE to the Preliminary Plat review process. BOND QUANTITY WORKSHEET,RETENTION/DETENTION FACILITY SUMMARY SHEET AND DECLARATION OF COVENANT NOT APPLICABLE to the Preliminary Plat review process. MAINTENANCE AND OPERATIONS MANUAL ' NOT APPLICABLE to the Preliminary Plat review process. r 15 A W A., a ' TABLE OF CONTENTS ' ITEM PAGE ' .Storm Drainage Calculations Natural Basin Discharges Existing East Basin 1 Existing West Basin 2 ' Developed Sub-basin Discharge West Sub-basin 3 East Sub-basins 4 East Sub-basin Detention Model Program 5-6 ' Storage and Discharge Structures Storage Structure 7 Discharge Structure 8 ' East Sub-basin Detention Model Results Program With Calculated Results 9-10 Vault Stage Storage Table 11 ' Discharge Stage Storage Table 12 ' East Sub-basin Detention Model Results w/Residence Infiltration. 13-14 Exhibit I-A - Natural Basin Map For Area 15 I-B - Site Existing Basin Map (See back pocket.) ' Exhibit II - Downstream Analysis by Lance Y.K.Gyotoku,P.E. 16-20 Exhibit III- Developed Sub-Basin Map (See back pocket.) ' STORM DRAINAGE CALCULATIONS 1 1 1 1 1 w U Q VO E-� Z 1 8/::)/97 2 , 5 :2 pm OLDS Inc. page 1 Whisper Pines BASIN SUMMARY 1 BASIN ID: eb2e.hyd NAME: 2 yr existing east basin SB UH METHODOLOGY TOTAL AREA. . . . . . . : 1 . 52 Acres BASEFLOWS : 0 . 00 cfs i RAINFALL TYPE. . . . : TYPElA PERV IMP PRECIPITATION. . . . : 2 . 00 inches AREA. . : 1.50 Acres 0 . 02 Acres TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 65 . 00 98 . 00 i TC. . . . . 17 .49 min 18 . 01 min ABSTRACTION COEFF: 0 .20 TcReach - Sheet L: 195 . 00 ns : 0 .1300 p2yr: 2 . 00 s : 0 . 0620 TcReach - Sheet L: 80 . 00 ns : 0 .2400 p2yr: 2 . 00 s : 0 . 2500 1 impTcReach - Sheet L: 30 . 00 ns:0 . 0110 p2yr: 2 . 00 s : 0 . 5000 impTcReach - Sheet L: 220 . 00 ns: 0 . 1300 p2yr: 2 . 00 s : 0 . 0545 impTcReach - Sheet L: 40 . 00 ns: 0.4000 p2yr: 2 . 00 s : 0 .4000 iPEAK RATE: 0 . 02 cfs VOL: 0 . 02 Ac-ft TIME: 1120 min BASIN ID: ebCe.hyd NAME: 100 yr existing east basin ' SBUH METHODOLOGY TCTAL AREA. . . . . . . • 1 .52 Acres BASEFLOWS : 0 . 00 cfs RAINFALL TYPE. . . . : TYPElA PERV IMP PRECIPITATION. . . . : 3 . 90 inches AREA. . : 1.50 Acres 0 . 02 Acres TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 65 . 00 98 . 00 TC. . . . : 17 .49 min 18 . 01 min A.RSTRACTION COEFF: 0 . 20 - ' PEAK RATE: 0 . 17 cfs VOL: 0 . 13 Ac-ft TIME: 490 min BP.SIN ID: ebXe.hyd NAME: 10 yr existing east basin ' SEUH METHODOLOGY TOTAL AREA. . . . . . . • 1 . 52 Acres BASEFLOWS : 0 . 00 cfs RAINFALL TYPE. . . . .. TYPElA PERV IMP i PRECIPITATION. . . . : 2 . 90 inches AREA. . : 1 . 50 Acres 0 . 02 Acres TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 65 . 00 98 . 00 TC. . . . : 17 .49 min 18 . 01 min ABSTRACTION COEFF: 0 . 20 1 PEAK RATE: 0 . 05 cfs VOL: 0 . 06 Ac-ft TIME: 960 min 1 i 1 i 1 ' 8/5/97 2 : 6 : 22 pm OLDS Inc . page 1 Whisper Pines ' BASIN ID: wb2e.hyd NAME: 2 yr existing west basin SBIJH METHODOLOGY TO-AL AREA. . . . . . . : 0 . 68 Acres BASEFLOWS : 0 . 00 cfs ' RA::NFALL TYPE. . . . : TYPEIA PERV IMP PRECIPITATION. . . . : 2 . 00 inches AREA. . : 0 . 53 Acres 0 . 14 Acres TI14E INTERVAL. . . . : 10 . 00 min CN. . . . : 65 . 00 98 . 00 ' TC. . . . : 22 . 11 min 1 . 86 min ABSTRACTION COEFF: 0 . 20 TcReach - Sheet L: 160 . 00 ns : 0 . 1500 p2yr: 2 . 00 s : 0 . 0125 t TcReach - Shallow L: 130 . 00 ks : 27 . 00 s : 0 . 0615 impTcReach - Sheet L: 40 . 00 ns : 0 . 0110 p2yr: 2 . 00 s : 0 . 5000 im]?TcReach Shallow L: 140 . 00 ks : 13 . 00 s : 0 . 0180 im]?TcReach - Shallow L: 130 . 00 ks :27 . 00 s : 0 . 0615 ' PEAK RATE : 0 . 06 cfs VOL: 0 . 03 Ac-ft TIME : 470 min BASIN ID: wbCe.hyd NAME: 100 yr existing west basin ' SBUH METHODOLOGY TOTAL AREA. . . . . . 0 . 68 Acres BASEFLOWS : 0 . 00 cfs RAINFALL TYPE. . . . : TYPEIA PERV IMP PRECIPITATION. . . . : 3 . 90 inches AREA. . : 0 . 53 Acres 0 . 14 Acres ' TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 65 . 00 98 . 00 TC. . . . . 22 . 11 min 1 . 86 min ABSTRACTION COEFF: 0 . 20 t impTcReach - Sheet L: 40 . 00 ns : 0 . 0110 p2yr: 2 . 00 s : 0 . 5000 impTcReach - Shallow L: 140 . 00 ks : 13 . 00 s : 0 . 0180 impTcReach - Shallow L: 130 . 00 ks : 27 . 00 s : 0 . 0615 ' PEAK RATE: 0 . 16 cfs VOL: 0 . 09 Ac-ft TIME : 480 min BASIN ID: wbXe .hyd NAME: 10 yr existing west basin SBUH METHODOLOGY ' TCTAL AREA. . . . . . . : 0 . 68 Acres BASEFLOWS : 0 . 00 cfs RAINFALL TYPE. . . . : TYPEIA PERV IMP PRECIPITATION. . . . : 2 . 90 inches AREA. . : 0 . 53 Acres 0 . 14 Acres ' TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 65 . 00 98 . 00 TC. . . . . 22 . 11 min 1 . 86 min AE',STRACTION COEFF: 0 .20 ' impTcReach - Sheet L: 40 . 00 ns: 0 . 0110 p2yr: 2 . 00 s : 0 . 5000 impTcReach - Shallow L: 140 . 00 ks : 13 . 00 s : 0 . 0180 impTcReach Shallow L: 130 . 00 ks : 27 . 00 s : 0 . 0615 PEAK RATE : 0 . 09 cfs VOL: 0 . 05 Ac-ft TIME: 470 min 1 1 1 ' 2 ' DEVELOPED SUB-BASIN DISCHARGES 1 1 ' 8/5/97 2 : 5 : 23 pm OLDS Inc . page 1 Whisper Pines BASIN SUMMARY ' BT,SIN ID: wb2d.hyd NAME: 2 yr developed west basin SPUH METHODOLOGY TOTAL AREA. . . . . . . : 0 .36 Acres BASEFLOWS : 0 . 00 cfs ' RAINFALL TYPE. . . . : TYPEIA PERV IMP PRECIPITATION. . . . : 2 . 00 inches AREA. . : 0 . 19 Acres 0 . 17 Acres T-.-ME INTERVAL. . . . : 10 . 00 min CN. . . . : 65 . 00 98 . 00 ' TC. . . . : 16 . 15 min 0 . 88 min ABSTRACTION COEFF: 0 . 20 TcReach - Sheet L: 95 . 00 ns : 0 . 1500 p2yr: 2 . 00 s : 0 . 0100 ' TcReach - Shallow L: 180 . 00 ks : 27 . 00 s : 0 . 0610 impTcReach - Sheet L: 20 . 00 ns : 0 . 0110 p2yr: 2 . 00 s : 0 . 0200 impTcReach Shallow L: 180 . 00 ks . 27 . 00 s . 0 . 0600 P.E'AK RATE: 0 . 07 cfs VOL: 0 . 03 Ac-ft TIME : 470 min ' BASIN ID: wbCd.hyd NAME: 100 yr developed west basin SBUH METHODOLOGY ' TOTAL AREA. . . . . . . 0 . 36 Acres BASEFLOWS : 0 . 00 cfs RAINFALL TYPE. . . TYPEIA PERV IMP PRECIPITATION. . . . : 3 . 90 inches AREA. . : 0 . 19 Acres 0 . 17 Acres TIME INTERVAL- , : 10 . 00 min CN. . . . : 65 . 00 98 . 00 ' TC. . . . : 16 . 15 min 0 . 87 min ABSTRACTION COEFF: 0 . 20 impTcReach - Sheet L: 20 . 00 ns : 0 . 0110 p2yr: 2 . 00 s : 0 . 0200 ' impTcReach - Shallow L: 180 . 00 ks : 27 . 00 s : 0 . 0610 PEAK RATE: 0 . 16 cfs VOL: 0 . 07 Ac-ft TIME : 470 min ' E;ASIN ID: wbXd.hyd NAME: 10 yr developed west basin SBUH METHODOLOGY TOTAL AREA. . . . . . . : 0 .36 Acres BASEFLOWS : 0 . 00 cfs RAINFALL TYPE . . . . : TYPEIA PERV IMP PRECIPITATION. . . . : 2 . 90 inches AREA. . : 0 . 19 Acres 0 . 17 Acres "IME INTERVAL. . . . : 10 . 00 min CN. . . . : 65 . 00 98 . 00 TC. . . . . 16 . 15 min 0 . 87 min ABSTRACTION COEFF: 0 . 20 :impTcReach - Sheet L: 20 . 00 ns : 0 . 0110 p2yr: 2 . 00 s : 0 . 0200 :impTcReach - Shallow L: 180 . 00 ks :27 . 00 s : 0 . 0610 ' :?EAK RATE: 0 . 11 cfs VOL: 0 . 05 Ac-ft TIME : 470 min 1 3 8/5/97 2 : 18 : 9 pm OLDS Inc. page 1 Whisper Pines BASINSUMMARY=====_______________________ BASIN ID: cbl .dev NAME : 100 YR. EAST BASIN CB 1 SBUH METHODOLOGY TOTAL AREA. . . . . . . : 0 . 39 Acres BASEFLOWS : 0 . 00 cfs RAINFALL TYPE. . . . : TYPElA PERV IMP PRECIPITATION. . . . : 3 . 90 inches AREA. . : 0 . 21 Acres 0 . 18 Acres TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 70 . 00 98 . 00 ' TC. . . . : 11 . 87 min 1 . 10 min ABSTRACTION COEFF: 0 . 20 TcReach - Sheet L: 90 . 00 ns : 0 . 1500 p2yr: 2 . 00 s : 0 . 0200 TcReach - Shallow L: 110 . 00 ks : 27 . 00 s : 0 . 0200 impTcReach - Sheet L: 40 . 00 ns : 0 . 0110 p2yr: 2 . 00 s : 0 . 0250 impTcReach Shallow L: 110 . 00 ks :27 . 00 s : 0 . 0250 PEAK RATE : 0 . 18 cfs VOL: 0 . 08 Ac-ft TIME : 470 min BASIN ID: cbl .dev NAME : 100 YR. EAST BASIN CB 3 SPUH METHODOLOGY TOTAL AREA. . . . . . . : 0 . 68 Acres BASEFLOWS : 0 . 00 cfs RAINFALL TYPE. . . . : TYPElA PERV IMP PRECIPITATION. . . . : 3 . 90 inches AREA. . : 0 . 36 Acres 0 . 32 Acres TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 70 . 00 98 . 00 TC. . . . : 12 . 00 min 1 . 28 min ABSTRACTION COEFF: 0 . 20 TcReach - Sheet L: 90 . 00 ns : 0 . 1500 p2yr: 2 . 00 s : 0 . 0200 ' TcReach - Shallow L: 155 . 00 ks : 27 . 00 s : 0 . 0250 impTcReach - Sheet L: 40 . 00 ns : 0 . 0110 p2yr: 2 . 00 s : 0 . 0250 impTcReach - Shallow L: 155 . 00 ks : 27 . 00 s : 0 . 0250 ' PEAK RATE: 0 . 33 cfs VOL: 0 . 14 Ac-ft TIME : 470 min BASIN ID: cb4 .dev NAME: 100 YR. EAST BASIN CB 4 S11UH METHODOLOGY ' TOTAL AREA. . . . . . . : 0 . 78 Acres BASEFLOWS : 0 . 00 cfs RAINFALL TYPE. . . . : TYPElA PERV IMP PRECIPITATION. . . . : 3 . 90 inches AREA. . : 0 . 30 Acres 0 .48 Acres TIME INTERVAL. . . . : 10 . 00 min CN. . . . : 70 . 00 98 . 00 TC. . . . . 12 . 18 min 1 . 38 min A13STRACTION COEFF: 0 . 20 TcReach - Sheet L: 90 . 00 ns : 0 . 1500 p2yr: 2 . 00 s : 0 . 0200 TcReach - Shallow L: 180 . 00 ks :27 . 00 s : 0 . 0200 impTcReach Sheet L: 40 . 00 ns : 0 . 0110 p2yr. 2 . 00 s : 0 . 0250 impTcReach - Shallow L: 180 . 00 ks :27 . 00 s : 0 . 0250 PEAK RATE: 0 . 45 cfs VOL: 0 . 18 Ac-ft TIME: 470 min 4 ' EAST SUB-BASIN DENTION MODEL PROGRAM Late of SE!ssion: 6/9/97 1 :22 :44 pm CLEARHIS tEMARK THIS PROGRAM HAS BEEN WRITTEN TO PROVIDE PRELIMINARY MODELLING F THE PLAT OF WHISPERING PINES STORM SYSTEM. THE FIRST STEP IS 0 UPDATE THE SUB-BASIN INFORMATION FOR A TWO YEAR STORM, HEN ROUTE A HYDROGRAPH THOUGH THE CATCH BASIN SYSTEM FOR THE EAST BASIN. THE TWO SYSTEM RUNS ARE THEN ADDED TOGETHER TO PROVIDE THE IN HYRDOGRAPH FOR THE LEVEL POOL ROUTING TABLE. STEND [HANGE DESCRIPTION 112 yr. East Basin CB 1, 3 & 4" HANGE PRECIP 2 . 00 cbl .dev cb3 .dev cb4 .dev (STEND ERO 1 20 ROUTE HYDROGRAPH 1 THROUGH REACH west ZERO IWOUTE HYDROGRAPH 2 THROUGH REACH cb4 ZERO D 1 2 3 kEMARK OW THE SUB-BASINS HAVE TO BE UPDATED FOR THE 10 YEAR STORM FOR A HYDROGRAPH RUN THROUGH THE CATCH BASIN SYSTEMS, THE HYDROGRAPHS tHE THEN ADDED TOGETHER TO PROVIDE THE 10 YEAR IN HYRDROGRAPH FOR E LEVEL, POOL ROUTING TABLE. LSTEND lHANGE DESCRIPTION 1110 yr. East Basin CB 1, 3 & 4" CHANGE PRECIP 2 . 90 bl .dev cbl .dev cbl .dev ISTEND ZERO 1 2 IOUTE HYDROGRAPH 1 THROUGH REACH west ZERO OUTE HYDROGRAPH 2 THROUGH REACH cb4 ZERO ADD 1 2 4 REMARK OW THE ;3UB-BASINS HAVE TO BE UPDATED FOR THE 100 YEAR STORM UE R A HYDROGRAPH RUN THROUGH THE CATCH BASIN SYSTEMS, THE HYDROGRAPHS THEN ADDED TOGETHER TO PROVIDE THE 100 YEAR IN HYRDROGRAPH FOR THE LEVE: POOL ROUTING TABLE. �STEND HANGE DESCRIPTION "100 yr. East Basin CB 1, 3 & 4" HANGE PRECIP 3 . 90 cbl .dev cb3 .dev cb4 .dev STEND iERO 1 2 ROUTE HYDROGRAPH 1 THROUGH REACH west ZERO UUTE HYDROGRAPH 2 THROUGH REACH cb4 ZERO D 1 2 5 1EMARK 5 loW THAT THE THREE FREQUENCY IN HYDROGRAPHS HAVE BEEN CALCULATED WE CAN NOW RUN THE LEVEL ROUTING TO SIZE THE FIFICES AND CALCULATE THE ELEVATIONS AND STORAGE REQUIREMENTS THE THREE DESIGN STORMS. LSTEND ,POOL 1 112 year" 0 . 010000 3 wspn wspn 6 LPOOL 2 1110 year" 0 . 050000 4 wspn wspn 7 (POOL 3 11100 yr" 0 . 170000 5 wspn wspn 8 1 1 1 i 1 1 1 1 1 1 1 1 1 i ' STORAGE AND DISCHARGE STRUCTURES 1 1 1 1 1 1 1 1 1 8/5/97 2 : 18 : 56 pm OLDS Inc . page 2 Whisper-Pines =====_______________________ STORAGE STRUCTURE LIST ' RECTANGULAR VAULT ID No. ws n P Description: CDS Vault ' Length: 70 . 00 ft . Width: 30 . 00 ft . voids : 1 . 000 t 7 8/5/97 2 : 21 :45 pm OLDS Inc . page 1 Whisper Pines DISCHARGE STRUCTURE LIST ' MULTIPLE ORIFICE ID No. wspn Description: Orifice tree for 2 , 10, 100 yr. Outlet Elev: 250 . 50 ' Elev: 248 . 50 ft Orifice Diameter: 0 .4578 in. Elev: 253 . 70 ft Orifice 2 Diameter: 1 . 0869 in. Elev: 255 . 20 ft Orifice 3 Diameter: 2 . 7598 in. 1 8 ' EAST SUB-BASIN DETENTION MODEL RESULTS 1 1 1 1 1 1 1 1 1 1 1 1 1 ' Eate of Session: 8/5/97 2 :13 :0 pm CLEARHIS ' REMARK THIS PROGRAM HAS BEEN WRITTEN TO PROVIDE PRELIMINARY MODELLING OF THE PLAT OF WHISPERING PINES STORM SYSTEM. THE FIRST STEP IS ' "'0 UPDATE THE SUB-BASIN INFORMATION FOR A TWO YEAR STORM, THEN ROUTE A HYDROGRAPH THOUGH THE CATCH BASIN SYSTEM FOR THE EAST BASIN. THE TWO SYSTEM RUNS ARE THEN ADDED TOGETHER TO PROVIDE THE IN HYRDOGRAPH FOR THE LEVEL POOL ROUTING TABLE. ' "STEND CHANGE DESCRIPTION 112 yr. East Basin CB 1,3 & 4" CHANGE PRECIP 2.00 ' cbl.dev cb3.dev cb4 .dev LSTEND ZERO 1 20 ' ROUTE HYDROGRAPH 1 THROUGH REACH west ZERO Network west Reach ----_-<AREA>-<Act--Q>_<Q_Full>-%-Full-Ndepth-<Diam>_<NVel>_<FVel>_Carea- cb3 0.68 0.13. 4 .16 3.23 1.53 12 . 00 2 .30 4 .93 cb3 .dev cbl 1.07 0.21 4 .16 5.04 1.90 12.00 2 .63 4 .93 cbl.dev ' ROUTE HYDROGRAPH 2 THROUGH REACH cb4 ZERO Reach -Area- --Qact-- --QFull- tFull Ndepth --Dia- -Vact- -Vfull Basn ' cb4 0.78 0.20 4.16 4.83 1.86 12 . 00 2 .60 4.93 cb4.dev ADD 1 2 3 0.4109 cfs 0.1620 ac-ft 7.83 hrs ' REMARK NOW THE SUB-BASINS HAVE TO BE UPDATED FOR THE 10 YEAR STORM ' FOR A HYDROGRAPH RUN THROUGH THE CATCH BASIN SYSTEMS, THE HYDROGRAPHS ARE THEN ADDED TOGETHER TO PROVIDE THE 10 YEAR IN HYRDROGRAPH FOR THE LEVEL POOL ROUTING TABLE. LSTEND ' CHANGE DESCRIPTION 1110 yr. East Basin CB 1,3 & 4" CHANGE PRECIP 2.90 cbl.dev cb3.dev cbl .dev ' LSTEND ZERO 1 2 ' ROUTE HYDROGRAPH 1 THROUGH REACH west ZERO Network west Reach <AREA> <Act Q> <Q Full> % Full Ndepth <Diam> <NVel> <FVel> Carea cb3 0.68 0.21 4.16 5.16 1.92 12 .00 2 .65 4.93 cb3 .dev cbl 1.07 0.34 4 .16 8.06 2 .39 12 .00 3 . 02 4.93 cbl.dev ' ROUTE HYDROGRAPH 2 THROUGH REACH cb4 ZERO Reach -Area- --Qact-- --QFull- °%Full Ndepth --Dia- -Vact- -Vfull Basn cb4 0.78 0.31 4 .16 7.46 2.30 12 .00 2 .95 4.93 cb4.dev 1 ' ADD 1 2 4 0.6464 cfs 0.2652 ac-ft 7.83 hrs ' REMARK NOW THE SUB-BASINS HAVE TO BE UPDATED FOR THE 100 YEAR STORM FOR A HYDROGRAPH RUN THROUGH THE CATCH BASIN SYSTEMS, THE HYDROGRAPHS ' 1,RE THEN ADDED TOGETHER TO PROVIDE THE 100 YEAR IN HYRDROGRAPH FOR "HE LEVEL POOL ROUTING TABLE. LSTEND ' CHANGE DESCRIPTION 11100 yr. East Basin CB 1,3 & 4" CHANGE PRECIP 3 . 90 ,::bl.dev cb3 .dev cb4 .dev LSTEND tZERO 1 2 ROUTE HYDROGRAPH 1 THROUGH REACH west ' Network west Reach <AREA> <Act Q> <Q Full> % Full Ndepth <Diam> <NVel> <FVel> Carea ----------------------------=------------------------------------------------ ----------------------------------------------------------------------------- ' cb3 0.68 0.33 4 .16 7.82 2.35 12.00 2 .99 4 . 93 cbl .dev cbl 1.07 0.51 4 .16 12.24 2.94 12.00 3 .41 4. 93 cbl.dev ROUTE HYDROGRAPH 2 THROUGH REACH cb4 ZERO ' Reach -Area- --Qact-- --QFull- %Full Ndepth --Dia- -Vact- -Vfull Basn cb4 0.78 0.45 4 .16 10.82 2.76 12.00 3 .29 4 .93 cb4 .dev ADD 1 2 5 0.9598 cfs 0.3902 ac-ft 7.83 hrs REMARK ' NOW THAT THE THREE FREQUENCY IN HYDROGRAPHS HAVE BEEN CALCULATED WE CAN NOW RUN THE LEVEL ROUTING TO SIZE THE ORIFICES AND CALCULATE THE ELEVATIONS AND STORAGE REQUIREMENTS ' FOR THE THREE DESIGN STORMS. LSTEND LPOOL 1 112 year" 0.010000 3 wspn wspn 6 Description MatchQ PeakQ Sto Dis PkStg OutQ hyd Volu 2 year 0.01 0.41 wspn wspn 253 .59 0.01 6 6,486 LPOOL 2 "10 year" 0.050000 4 wspn wspn 7 ' Description MatchQ PeakQ Sto Dis PkStg OutQ hyd Volu 10 year 0.05 0.65 wspn wspn 255.09 0.05 7 9,637 LPOOL 3 11100 yr" 0,170000 5 wspn wspn 8 ' Description MatchQ PeakQ Sto Dis PkStg OutQ hyd Volu 100 yr 0.17 0. 96 wspn wspn 255.51 0.17 8 10,512 End program file D:\BNNT-0-1\CALCS\WSPN.pgm 8/5/97 2 : 20 : 52 pm OLDS Inc . page 1 Whisper Pines STAGE STORAGE TABLE ' RECTANGULAR VAULT ID No. wspn Description: CDS Vault Length: 70 . 00 ft . Width: 30 . 00 ft . voids : 1 . 000 ' STAGE <----STORAGE----> STAGE <----STORAGE----> STAGE <----STORAGE----> STAGE <----STORAGE----> (ft) ---cf--- --Ac-Ft- (ft) ---cf--- --Ac-Ft- (ft) ---cf--- --Ac-Ft- (ft) ---cf--- --Ac-Ft- ' 2'_,0.50 0.0000 0.0000 251.80 2730 0.0627 253.10 5460 0.1253 254.40 8190 0.1880 2S0.60 210.00 0.0048 251.90 2940 0.0675 253.20 5670 0.1302 254.50 8400 0.1928 2'.;0.70 420.00 0.0096 252.00 3150 0.0723 253.30 5880 0.1350 254.60 8610 0.1977 250.80 630.00 0.0145 252.10 3360 0.0771 213.40 6190 0.1318 254.70 8120 0.2025 ' 250.90 840.00 0.0193 252.20 3570 0.0820 253.50 6300 0.1446 254.80 9030 0.2073 251.00 1050 0.0241 252.30 3780 0.0868 253.60 6510 0.1494 254.90 9240 0.2121 251.10 1260 0.0289 252.40 3990 0.0916 253.70 6720 0.1543 255.00 9450 0.2169 ' 251.20 1470 0.0337 252.50 4200 0.0964 253.80 6930 0.1591 255.10 9660 0.2218 251.30 1680 0.0386 252.60 4410 0.1012 253.90 7140 0.1639 255.20 9870 0.2266 251.40 1890 0.0434 252.70 4620 0.1061 254.00 7350 0.1687 255.30 10080 0.2314 251.50 2100 0.0482 252.80 4130 0.1109 254.10 7560 0.1736 255.40 10290 0.2362 251.60 2310 0.0530 252.90 5040 0.1157 254.20 7770 0.1784 255.50 10500 0.2410 251.70 2520 0.0579 253.00 5250 0.1205 254.30 7980 0.1832 255.60 10710 0.2459 ' II 8/5/97 2 : 21 :45 pm OLDS Inc . page 2 -------Whisper_Pines __________________ STAGE DISCHARGE TABLE ' MULTIPLE ORIFICE ID No. wspn Description: Orifice tree for 2 , 10, 100 yr. ' Outlet Elev: 250 . 50 Elev: 248 . 50 ft Orifice Diameter: 0 .4578 in. Elev: 253 . 70 ft Orifice 2 Diameter: 1. 0869 in. Elev: 255 . 20 ft Orifice 3 Diameter: 2 . 7598 in. ' STAGE <--DISCHARGE---> STAGE <--DISCHARGE---> STAGE <--DISCHARGE---> STAGE <--DISCHARGE---> (ft) ---Cfs-- ------- (ft) ---Cfs-- ------- (ft) ---Cfs-- ------- (ft) ---Cfs-- ------- 250.50 0.0100 251.80 0.0065 253.10 0.0092 254.40 0.0311 250.60 0.0018 251.90 0.0067 253.20 0.0093 254.50 0.0400 2S0.70 0.0025 252.00 0.0070 253.30 0.0095 254.60 0.0419 250.80 0.0031 252.10 0.0072 253.40 0.0097 254.70 0.0437 ' 250.90 0.0036 252.20 0.0074 253.50 0.0098 254.80 0.0454 251.00 0.0040 252.30 0.0076 253.60 0.0100 254.90 0.0470 251.10 0.0044 252.40 0.0078 253.70 0.0102 255.00 0.0486 251.20 0.0041 252.50 0.0080 253.80 0.0205 255.10 0.0501 251.30 0.0051 252.60 0.0082 253.90 0.0248 255.20 0.0516 251.40 0.0054 252.70 0.0084 254.00 0.0282 255.30 0.1184 251.50 0.0057 252.80 0.0086 254.10 0.0311 255.40 0.1468 ' 251.60 0.0060 252.90 0.0088 254.20 0.0336 255.50 0.1689 251.70 0.0062 253.00 0.0090 254.30 0.0359 255.60 0.1878 t ' 12 ' EAST SUB-BASIN DETENTION MODEL RESULTS, WITH RESIDENCE INFILTRATION 1 1 1 1 1 1 Date of Session: 6/10/97 11:19:26 am CLEARHIS ' REMARK THIS PROGRAM HAS BEEN WRITTEN TO PROVIDE PRELIMINARY MODELLING CF THE PLAT OF WHISPERING PINES STORM SYSTEM. THE FIRST STEP IS TO UPDATE THE SUB-BASIN INFORMATION FOR A TWO YEAR STORM, THEN ROUTE A HYDROGRAPH THOUGH THE CATCH BASIN SYSTEM FOR THE EAST EASIN. THE TWO SYSTEM RUNS ARE THEN ADDED TOGETHER TO PROVIDE THE IN HYRDOGRAPH FOR THE LEVEL POOL ROUTING TABLE. LSTEND CHANGE DESCRIPTION 112 yr. East Basin CB 1,3 & 4" CHANGE PRECIP 2.00 ' cbl.dev cbl .dev cb4 .dev .=END ZERO 1 20 ' ROUTE HYDROGRAPH 1 THROUGH REACH west ZERO Network west Reach -__,---<AREA>-<Act_-Q>_<Q-Full>_%_Full-Ndepth-<Diam>-<NVel>_<FVel>-Carea- cb3 0.60 0.10 4 .16 2.39 1.33 12 .00 2 .11 4 .93 cbl .dev cbl 0.95 0.16 4 .16 3 .80 1.66 12 .00 2 .42 4. 93 cbl.dev ' ROUTE HYDROGRAPH 2 THROUGH REACH cb4 ZERO Reach -Area- --Qact-- --QFull- %Full Ndepth --Dia- -Vact- -Vfull Basn ' cb4 0.42 0.09 4 .16 2.09 1.24 12.00 2 .02 4.93 cb4.dev ADD 1 2 3 0.2455 cfs 0.0952 ac-ft 7.83 hrs REMARK NOW THE SUB-BASINS HAVE TO BE UPDATED FOR THE 10 YEAR STORM FOR A HYDROGRAPH RUN THROUGH THE CATCH BASIN SYSTEMS, THE HYDROGRAPHS ARE THEN ADDED TOGETHER TO PROVIDE THE 10 YEAR IN HYRDROGRAPH FOR THE LEVEL POOL ROUTING TABLE. LSTEND CHANGE DESCRIPTION 1110 yr. East Basin CB 1,3 & 4" CHANGE PRECIP 2 .90 cbl.dev cb3 .dev cbl .dev 1 LSTEND ZERO 1 2 ROUTE HYDROGRAPH 1 THROUGH REACH west ZERO Network west Reach <AREA> <Act Q> <Q Full> % Full Ndepth <Diam> <NVel> <FVel> Carea ------------ cb3 0.60 0 .15 4 .16 3 .58 1.61 12.00 2 .38 4.93 cb3.dev cbl 0.95 0.24 4 .16 5.69 2 .01 12.00 2 .73 4 .93 cbl.dev ROUTE HYDROGRAPH 2 THROUGH REACH cb4 ZERO Reach -Area- --Qact-- --QFull- %Full Ndepth --Dia- -Vact- -Vfull Basn cb4 0.42 0.13 4 .16 3 .12 1.51 12 .00 2.28 4 .93 cb4 .dev 13 1 ' ADD 1 2 4 0.3670 cfs 0.1599 ac-ft 7. 83 hrs ' RI'MARK NOW THE SUB-BASINS HAVE TO BE UPDATED FOR THE 100 YEAR STORM FOR A HYDROGRAPH RUN THROUGH THE CATCH BASIN SYSTEMS, THE HYDROGRAPHS ARE THEN ADDED TOGETHER TO PROVIDE THE 100 YEAR IN HYRDROGRAPH FOR ' THE LEVEL POOL ROUTING TABLE. LSTEND ' CHANGE DESCRIPTION 11100 yr. East Basin CB 1, 3 & 4" CHANGE PRECIP 3 . 90 cbl.dev cbl .dev cbl .dev LSTEND ' i;ERO 1 2 ROUTE HYDROGRAPH 1 THROUGH REACH west ' Network west ]teach <AREA> <Act Q> <Q Full> % Full Ndepth <Diam> <NVel> <FVel> Carea ' cb3 0.60 0 .23 4.16 5.50 1. 98 12 . 00 2 . 70 4 . 93 cbl .dev cbl 0 . 95 0 .36 4.16 8.73 2 .48 12 .00 3 . 09 4 . 93 cbl.dev ROUTE HYDROGRAPH 2 THROUGH REACH cb4 ZERO ' Reach -Area- --Qact-- --QFull- %Full Ndepth --Dia- -Vast- -Vfull Basn cb4 0.42 0 .19 4 .16 4 .61 1 .82 12 . 00 2 . 56 4 .93 cb4 .dev ADD 1 2 5 0 .5555 cfs 0.2416 ac-ft 7 . 83 hrs REMARK ' NOW THAT THE THREE FREQUENCY IN HYDROGRAPHS HAVE BEEN CALCULATED WE CAN NOW RUN THE LEVEL ROUTING TO SIZE THE ORIFICES AND CALCULATE THE ELEVATIONS AND STORAGE REQUIREMENTS t FOR THE THREE DESIGN STORMS. LSTEND LPOOL 1 112 year" 0 .020000 3 wspn wspn 6 t Description MatchQ PeakQ Sto Dis PkStg OutQ hyd Volu 2 year 0.02 0.25 wspn wspn 253 .22 0.02 6 3126Z LPOOL 2 1110 year" 0 . 050000 4 wspn wspn 7 ' Description MatchQ PeakQ Sto Dis PkStg OutQ hyd Volu 10 year 0.05 0.37 wspn wspn 253 .79 0.02 7 1791 LPOOL 3 11100 yr" 0 . 170000 5 wspn wspn 8 Description MatchQ PeakQ Sto Dis PkStg OutQ hyd Volu 100 yr 0. 17 0.56 wspn wspn 254 .35 0.05 8 8324 End program file D:\BNNT-0-1\CALCS\WSPN.pgm 1 14 H w 1 1 EXHIBIT I-A /��///,rt �`�' .T.- 1• _pe,e_ � 1 ! Tn+er {t,� I: \ U J�(! !r �' Ire''. �• \ , ..ram r .f. � \ -c1 � � � Creek 01Prk 1'\� � -.SI)�� 'o III 1 � �• rr 111 ��• � 11�� ,r=�. . I — y �• � / ` _ �. Ire ��// ' ,/_ � L�I•) r�%�i`� .` \\ ,\ ,�r \ ;II it / /�I' (/ . �, �; �• '`�'^.:'•� �. � � ,, ram'' � ' ROr+�x-.�—✓r �� ;\1, �� �\� '1 � •L ra'V. I-" �^ •.�1� .�. r., ,� / C ( o`\\ P''kr ' I �.\\` 1 A ;i� 9m May Creek Basin set l r R W".y W J Ir I p ,�. •' �1.1 �• 1 / 1 1 1 1 ►--� H �--i w DOWNSTREAM ANALYSIS ' THE PRELIMINARY PLAT OF WHISPERING PINES May 6, 1995 G� WAS yOl� r 30725 ISTER� ' sS��NAL�G (i t11 <01 EXPIRES 3/3/�:�- ' PREPARED BY: Lance Y.K. Gyotoku, P.E. ' 1G The Plat of Whispering Pines Downstream Analysis I BELCH PAFlK xTH' 2 -- IT t \ ' T + - IF 91sl �R KENNYDAL MN ISND I�OJH AVHVEM T ST ST coN�uA.v N z rN STmT p7 i C >k 'ems a MN Pl ❑ N n SL_ 7TTN M z "'Fins I C t�THST h i n ton E i ME T:L ` IN? P•S _ 5 N TH IM Si I ` WE 1lTH ME 1 ST y PL y 1 !! r NE �•� W � ANO Nf 6TN' T y }i NE u Lw .. R ISl L NEW ST 17T r S:#: n< I .\ EjOAR • 1. ST I I i OR ^• S LIST" ST 116TN' TLAUNCN ST,n •I m N! LOTH T $117TX ST REHTON \Y� 2 E BTN P S 117T" u) 12 N yy v NT tn s > : i ST I lt__ Q 1 Z ET" ST : > F t EETNPL 1, .ENI ONY N N T LU� Tkl > L STm n as $ 12YWST i rT 11 .Hon¢ns.....E ST s PABK : Hcr w„ml 41 12 PL � �1 <" • 1 �l{$qT� 'i]1 • it OIL. 11P BUBNf)1 pp� ••NE ST" r Figure 1: Vicinity Map Not to Scale 17 ' The Plat of Whispering Pines Downstream Analysis ' Proiect Overview The site is located on the east side of Jones Avenue NE between NE 28th Street and NE 24th ' Street and is composed of approximately 2.7 acres. The proposed development will consist of 11 single-family residential lots, with a cul-de-sac public road and detention system. Site Conditions The site is consists of mainly cleared land with a 2 story barn. There is a high point near the westerly third of the site that slopes to the West at 6%. To the East the grade falls generally east at a slope of 6.5% until the defined bank near the northeast corner at which point the grade drops 14 feet in roughly 25 feet. The site would be classified as.pasture land with very poor vegetation coverage. The area of the Northeast of the bank is undeveloped and would be considered young second growth. Existing Drainage The site is located within the Cedar River Drainage Basin, and the East Lake Washington Sub- Basin. Runoff from this site presently sheetflows the East and to the West. There are no drainage conveyance structures, swales, or ditches onsite to channelize flow. The site probably infiltrates rainfall from smaller storms, and sheetflows the larger storm events. Proposed Drainage The proposed plat will provide an underground drainage system that will collect runoff and direct it to the detention tank located in the cul-de-sac. This tank will outflow into a grass-lined ' )iofiltration system and ultimately discharge to the low point of the site (the northeast corner). 'The vault and biofiltration system will be sized using the current City of Renton design standards. Downstream Analysis 'The proposed storm system will discharge into the low point of the site located at the bottom of the bank near the northeast corner. The runoff enters a wetland-type area that is very heavily vegetated. A slight ditch is present in this area and runs in a northerly direction for roughly 210 feet at a very gradual, flat slope. (Please refer to Figure 2, Point "A".) This ditch has bottom 1vidth that varies from 2 to 5 feet with a depth that also varies from 0.5 to 1.0 feet. The area ' surrounding this ditch is very low and wooded. There is no evidence of erosion or very heavy flows. This drainage course then intersects NE 27th Street where it enters a 24" CMP culvert. ' (Point `B") This culvert is partially blocked with debris. The headwall created by NE 27th Street roughly extends 3 feet above the culvert. This culvert crosses NE 27th Street in a northwesterly direction where it terminates in a manhole. This manhole discharges into a heavily landscaped ornamental pond/stream system located on private property. (Point "C") The pond and stream Ere located approximately 4 feet vertically and 20 feet horizontally from the property owner's homes. This drainage course continues to wind thru private property in a northerly direction for ' about 300 feet. The drainage course then intersects NE 29th Court. The drainage course now f as a section with a bottom width of 1.5 feet, and vertical 2 foot high rockery-type side walls. From these rockery walls, the grade extends up at a 2:1 slope to an additional depth of 7 feet. ' These side slopes are covered with mowed grass in very good condition. (Point "D") The channel enters a 24" CMP pipe and crosses the street. The 24" CMP inlet seemed to be in good working order. (Point "E") From this pipe the drainage system enters the Canyon Oaks ' Townhome Development. The outfall is located in the back of the buildings, roughly 150 feet from the 24" CMP inlet. It is not known exactly where the conveyance pipes are on this property. ' The Plat of Whispering Pines Downstream Analysis tIt is believed that the drainage course discharges from a 36" CMP pipe which daylights from a steep slope. (Point "F") The runoff discharges into an energy-dissipation pool approximately 5 ' feet in diameter. (Point "G") The runoff then overflows from -the pool into a very defined, heavily vegetated and wooded channel that is sloped at roughly 2.5:1 and runs northeasterly toward May Creek. This area was not easily accessible for further observation due to the slope. ' There seemed to be no evidence throughout this downstream course of any erosion or drainage problems. It is assumed that the 24" culvert at NE 27th Street does backup and accumulate some water depth due to the debris at the inlet. Due to the ample height of the headwall and surrounding area, this does not seem to be a problem. ' This proposed development will not have a significant impact on the downstream properties with respect to erosion or capacity. Further research of city and county records will be necessary to tanalyze the remaining downstream drainage system. 1 t ' ? 9 The Plat of Whispering Pines Downstream Analysis I JJ4.t0 si w I J9.91 365 y A44Yt CREEK P I I 364 l5 56.95 s 58� 57 31 to '65 67 I� P 0 S E p Igo 5-16z I, ` E E eoz9a -- it ' I z � ----- SS ' 54 e� --- 39 ` C I K I I I" � ze TR. • I 1 6, P A R K & F _ j G 1 /a 07: an 'u �q.1 llp t 20 / I t '571 9 \" . 1511 Z587 t% t„ p% 82 O1 FORM R -10 4126 ,y fib, \� •( ' 2197 II06 5p2 69 y s ~r 4 5 I ,39 �95,5 53 ✓ j� So 6 I � Ty Z t Ss i5991 titi o6099r i N '{..- _ E S �A � E co, ••�.�3. Ti `- /eyl3 l� IS �70 11 io n.3 I ?6 F �? 5 [c I I� k-- 590/os 73 74.ar (01 Z 1 22 r ?a Q -�-$-, 7 217 H �I Io 11N n I 7 1 I I I (J- 180 198 �� I!279 In I ! f! I 0 I b • i �^ 1 M1 bl N f ^[ 2 89.3 • I 55 1 0 1 r ! I r 100 65 f 700 1 //2 2 3 2 51y �S r TE ----3�----- ' - I I IiI�G 17 6 N 7 i. I 1 h •5' H I In 1 — /00 9 �1 300 ' 7t5 o 3 za e7 !1.Sf h ti 252.3 ------ .� Figure 2: Downstream Analysis Exhibit Scale 1"=200' m m m m m m m m m m m m m m m m m m m �, PRELIMINARY PLAT OF o LEGAL DESCRIPTION PARCEL 3 f— THAT PORTION OF TRACTS 255, 256, 257, 275, 276, 277 OF C.D. N WHISPERING PINES HILLMAN'S LAKE WASHINGTON GARDEN OF EDEN DIVISION NO. 4, ACCORDING w 3 9 n rn R C E L 3 OF CITY OF RENTON LOT LINE ADJUSTMENT N 0. 010 8 6 TO THE PLAT THEREOF RECORDED IN VOLUME 11 OF PLATS, PAGE 82, (n PA RECORDS OF KING COUNTY, WASHINGTON, DESCRIBED AS FOLLOWS: BEGINNING AT THE NORTHWEST CORNER OF TRACT 277; THENCE SOUTH 89'43'59" EAST 114.44 FEET ALONG THE NORTH LINE OF n N.E. 28TH STREET SAID TRACT TO THE TRUE POINT OF BEGINNING; ® _ _ _ _ THENCE CONTINUING SOUTH 89'43'59" EAST 517.18 FEET; THENCE SOUTH 00'34'06" WEST 221.97 FEET TO A POINT ON THE SOUTH n LINE OF SAID TRACT 255; THENCE SOUTH 89'59'33" WEST 517.62 FEET ALONG THE SOUTHERLY LINE OF TRACTS 255 AND 275; LL THENCE NORTH 00'33'45 ' EAST 80.05 FEET; O � o W F- THE NLEFNOHAVIN89A RADIUS WEST OF 201FEET,ET TO THE BEGINNING OF CURVE TO m Q Z W Q THENCE ALONG SAID CURVE THROUGH A CENTRAL ANGLE OF 89'34'02", -i Z HAVING AN ARC LENGTH OF 31.26 FEET TO A POINT ON THE EAST LINE } n Z JONES AVENUE; Ld 0 1 .30 O ,j0 60 THENCE NORTH 00'33'45" EAST 90 FEET ALONG SAID LINE; Z m z FIRE HYDRANT SCALE /N FEET ' � � � O THENCE SOUTH 00'33'45' WEST THROUGH A CENTRAL ANGLE OF 90'25'58" HAVING AN ARC LENGTH OF 31.57 FEET; Cn Z LiJ >- z I f;' THENCE SOUTH 89'52'13" EAST 94.29 FEET, - U W THENCE NORTH 00'33'45" EAST 94.40 FEET TO THE TRUE POINT OF ' cn BEGINNING.z � W 3343902181 3343902180 (ALSO KNOWN AS PARCEL 3 OF CITY OF RENTON LOT LINE ADJUSTMENT NO. D 010-86, RECORDED UNDER RECORDING NO. 8609229011.) Y / LJ 30" CED 30" FIR A-1 SITUATE IN THE COUNTY OF KING, STATE OF WASHINGTON. v� BARBED-WIRE FENCE N 8W43'59" W Ld Q_a r W 2"\ RELZ 'W o 18" FIR 32" MAP V) QDRIVEWA t- I30 33 3902845 26" FIR \ Z _ a y "/ �� {►d l�� �� F a o /4) S Ld �/ \ \LJ NOT PART OF •Z /4c.. N THIS SUBDIVISION 32" FIR \ \ j 4 \ \ �}ST ! ` M _ 2 'y9' /�' c V . \ �O \�� 3 3343902061 a O � � ASPH L 2 STORY W000 w J FRAME HOUSE _ S 1 2616 JONES AVE. N.E J` O \ " OJ 30 FIR 1—� 4 SANITARY SEWER MH� Q I w = 90'25'58" oA �v �� A-7 c ~ R = 20.QO' z 1 a DRIVEWAY = 31.5 �, - _ -- — �_ - \,p,_5 A-6 ) - 0 v N 89*52'13" W , __WIRE FENCE Q ~o N o 0 0 0 0 0 0 0Ld W z -0�\ N� F �� E� �I e�o o, O • ZD ti� o, cc 18".30&34" UTILITY POLE S"`. 2 �� T ----------COTTON WOO D CL TER\ �� UTILITY POLE � x ? _ I I ASPHALTg AIN-LINK FENCE - �! N 8 '52 W ,� � RIDGE __ co 9'34'02" p SANITARY SEWER MH/ �= s� INE l f p Q / j 'o IE = 243t Q = 3 .26' %It "% \ ��� / >N 3343902840 Q - / o CONC. EsT �� Itp ,... y �/� L�s7" As t t- z cn DRIVEWAY c � 'sir 9- crLLJ a d k. O Q a J DRIVEWAYHP. �N�7$ 6o.�� +C rO + J1►0�'-- - -_ x - -- . r. vd �G W U Q y Z '�.. G/�= Ga? D. 'f�/AG , i 1� = -o T " NWT co w I"" Q � X - II W z Y I �j w R7 EXISTING 2- a o F Z 30' NOT PART OF 1 , G. g Am. .d z _ �. 'S Z. A c-- 3343902120 THIS SUBDIVISION w SINGLE STORY HOUSE :`� c> 0 r/ 2612 JONES AVE. N.E. o -- N w Z --- __ - \� Q �c� � . WOOD\ FE CE o o WOOD FENC - - --— - - - - - v� - - ----- - _ - N--S9rJ� E- rJ17 6 fro iM00D FENCE n - \ OWER 7til) n e o g o U � o W o �3343903638 23 22 21 20 19 18 Ld w w 3343903641 / F U i Q x Ix WATER MH SANITARY SEWER MH/ I 3343902803 3343903639 CATCH BASIN 24 m FIRE HYDRANT WATER VALV (TYP) \ z LEGEND 0 w W PROPOSED WATER LINE BENCHMARK EXISTING WATER LNE ® FND. 6" ROUND CONCRETE MONUMENT W/ NAIL IN CASE. WA TER ELEV = 239.77 SAN SEWER EXISTING SAN SEWER VERTICAL DATUM_ SS PROPOSED SANITARY SEWER LINE CITY OF RENTON AA-2 WETLAND FLAG Q 0 A -INNININJAIA Z w I PRELIMINARY PLAT OF WHISPERING PINES � o PARCEL 3 OF CITY OF RENTON LOT LINE ADJUSTMENT NO . 010 - 86 ri N.E. 28TH STREET - - -- - - LL 42' R/W 0 c 10' PLANTER/ 10' PLANILR/ z W _ UTILITY ESM'T 5' S/W 16' 16' 5' S/W UTILITY ESM'T W <C � � �� z w � V , CD LLJ C) VERTICAL o z m z a m CURB (TYP)U' a �o 0 30 6o N 0 TE z � - CD \ � � SCALE /NFEE� _ _ _ ALL TREES LYING ALONG 2fiTH AVE. N.E. z Lij }- I___ TO BE REMOVED Q — a- C) W Q I' � 3343902181 3343902180 LLJz \ 1�� PROPOSED ROAD SECTION k � N. T. S. 4 '(a A-1 Li I----- = 3a CEy N a 89 43`59" ' .f - Y t.� 60 w 0 60 28 _ z �. i 750' a i�1 30 I 33 3902845 r� 26" T9R ORI VL WAY 0 F � I -1 I 15' B.S.B.L. 5' \ B9- \ o BOG' ,�\ A-2 LOT I o ► z 0 0 ( ��% LOT �1 I coI LOT 2 I � I LOT 3 I OT "+ , I \ LOT 1 5,500 s ft. 5,500 s �t co 5 0 s t. 32' . ♦ \ � • 5,500 s ft. 1 q I ( q I co,I q o _ q s� � ,� 7,062 s\q-ft. \?>o t WETLANDS a O Lo 1 I, NEW LIGHT w I I i I I I cn 3 v it STANDARD (TYP) o �.\ \ -3 r3343902061 w FLOW SPREADER N E-� / NEW SAN. o I \ YDR T - -- ►—+ W A = 90'25'58" SEWER MH (lYP) — — ��� — — — — — -J L - — — — �-\— — — — L-\ — — — — — — -7 . r - y . N Q z 15' B.S.B.L. \ \ A W avRI V[SYA Y R = 20.00' T �. ---- ` 31.57 89-5213" W �^' - 1C; 10' WIDE PLANTER 9 �O\ 5 60 L41RG r E / � . ,� `'-, 26 TH A V N.. CB-3 N iE-255.7 1 I o W c _ O `t s W _:r W �,r,'N�. g '13 W 474' F O i' o C.O. - - g SS _ SS SS SS ! R/W AREA - U 1Ii__ITY POLE - CB- - - r! t o t 2 N cp _ _ „ N 28,572 s .ft. 15' CITY OF RENTON URL ITY POLE nr � 87' UTILITY EASEMENT CONC. SIDE LK 91 � 52' 10,300 C.E. - 9' N 89'S2 W UTILITY ESM'T b DETENTION VAULT o SAN SE"t,V�Rt . I -- \ - - - - -.B B.L. - - y - - - - IE 5 \ _ _ 20.00' Z - _.- _ \ t1, — — — 15' B.S . . CB-1 >i =250. o Wti iE 24?� ! J 31.26' � i 3343902840 �'T GR=259.20 O INSIINSIDE ODE OTTOMLEL-5250050 ' T o >� ! �z_..___ _ __ _r___ g I z RELOCATED EXIsnNc ; , CONc. , 39.6' ; I I I I \ I 1 , UTILITY POLE cr QRtVE iYA\ t O v \ x '� I I I I \ I I Lo 7 0 �n,�EyvAY = ; �, ,� \ °° LOT 6 J I I N ,o.e' 7rl._..g .. _ -- 7,46 7 s f t. -- . o wzz �� � I LOT 10� I �I LOT 9 0 ��----.- 41�_ co q• -- - - _ � �°' / 13,141 sq.ft. W NEW fIREI•iYDANT ca ; ^L._ w 5 500 s ft. 5 500 s .ft.v \ _ = o o :I ) 00 sq.ft. I I q I . q I I 67, 3343902120 '] o a z i 30' j , � LOT 2 :i _ I— —�— --1 � 25' S.S.B C,4 LJ L_ � L- _ � � s `.� � �il�Vl_L Sl�J�+ 1I✓IJNi.. • 1 I � � ! _ ' 2612 JONES ."41 . N.E. i 0� � /� 41 -- - w. 1 t.: z _ , Gr - tea' __ # - �:— - _-- _ - N — - -_-- - --- .. _ I - --- - - - ---- -- ---- -- - - -- �' --- - - --- - ........ 0'r C� ______-- _-_._ __ - v �; _�,__`� \ h —_a �}.8J5933`E- _ __5TT.62` - - ------ -------- - - - -r---- ' • i 1 0 280 0 4s,t i i{ 1 I \ 1 ` •,-o i� ! { ; 3343903638 1 1 \ CL d �zCL Lli � 3343903641 \` I � I LLJ t x ! ! { L. m WA DER Mfti � ' 3343902803 ' I ��N�rng� s�;�.r? MF��• I I • 3343903639 CATc^i BAs:r: I i I t • I . . LEGEND z W PROPOSED WATER LINE OWNER: NANCY BENNETT O 2612 JONES AVE. N.E. U' WATER EXISTING WATER LNE RENTON, WASHINGTON 98056 w SAN SEWER EXISTING SAN SEWER SURVEYOR: KEVIN VANDERZANDEN P.L.S. NO. 30427 SS PROPOSED SANITARY SEWER LINE AA-2 WETLAND FLAG Z oz A I V NININJAIA w