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L..mil1anr!ing U5 SW 155th .~ Sum 101 Seattle. wasnmgum 98166 Phone 206.244.4Ul Far 206.lU./455 Neighborhood Detail Map f 7 Site@ 16808 & 16816 106° Ave SE Renton, WA 98055 Scale: A:, specified Drawn: KCF Job No: 07764 ' GEOTECHNICAL ENGINEERING STUDY TALBOT HEIGHTS SINGLE-FAMILY RESIDENCE DEVELOPMENT 16808 AND 16816106TH AVENUE SOUTHEAST KING COUNTY, WASHINGTON October 29, 2007 Project No. E-13050 Prepared for RW Puget Sound Holdings, LLC 2011 South 341 st Place Federal Way, Washington 98003 C, EARTH CONSUL TING INCORPORATED 1805 136th Place Northeast Suite 201 Bellevue, Washington 98005 (425) 643-3780 Toll Free 1-888-739-66 70 C, EARTH CONSULTING INCORPORATED October 29, 2007 Mr. Russ Hibbard RW Puget Sound Holdings, LLC 2011 South 341 st Place Federal Way, Washington 98003 Project No. E-13050 Dear Mr. Hibbard: U Constr:.;ction Materials Test11~g .J Specis.l Inspections Earth Consulting Incorporated (ECI) is pleased to submit our report titled "Geotechnical Engineering Study, Talbot Heights Single-Family Residence Development, 16808 and 16816 106th Avenue Southeast, King County, Washington." This report presents the results of our field exploration, selective laboratory tests, and engineering analyses. The purpose and scope of our study were outlined in our September 12, 2007, proposal. We appreciate this opportunity to be of service to you. If you have any questions, or if we can be of further assistance, please call. Respectfully submitted, EARTH CONSUL TING INCORPORATED Steve J. Scharf Senior Staff Geologist SJS/KMW/skp tbP@s 02-00-01 Kristina M. Weller, PE Principal 1805 136'" Place Northeast #201 • Bellevue, WA 98005 • (425) 643-3780 • Fax (425) 746-0860 eci@eci-mti.com • www.eci-mti.com TABLE OF CONTENTS E-13050 PAGE INTRODUCTION .................................................................................................................. 1 General ..................................................................................................................... 1 Project Description ................................................................................................. 1 Scope of Services ................................................................................................... 2 SITE CONDITIONS .............................................................................................................. 3 Surface ..................................................................................................................... 3 Subsurface ............................................................................................................... 3 Geologic Map Review .................................................................................... 3 Subsurface Exploration .................................................................................. 3 Groundwater ............................................................................................................ 4 Laboratory Testing .................................................................................................. 4 DISCUSSION AND RECOMMENDATIONS ....................................................................... 5 General ..................................................................................................................... 5 Site Preparation and General Earthwork .............................................................. 5 Stripping ......................................................................................................... 5 Structural Fill .................................................................................................. 6 Foundations ............................................................................................................. 6 Retaining Walls ........................................................................................................ 7 Slab-on-Grade Floors ............................................................................................. 8 Seismic Design Considerations ............................................................................ 8 GroundRu~ra ............................................................................................. 8 Liquefaction .................................................................................................... 8 Ground Motion Response .............................................................................. 9 Excavations and Slopes ......................................................................................... 9 Site Drainage ......................................................................................................... 10 Utility Support and Backfill .................................................................................. 10 Suggested Pavement Sections ............................................................................ 10 LIMIT ATIONS .•.•.•.•.................................................................•...•....................................•.. 11 Additional Services ............................................................................................... 11 ILLUSTRATIONS Plate 1 Plate 2 Plate 3 APPENDICES Appendix A Plate A1 Plates A2 through A9 Appendix B Plates 81 TABLE OF CONTENTS, Continued E-13050 Vicinity Map Test Pit Location Plan Typical Footing Subdrain Detail Field Exploration Legend Test Pit Logs Laboratory Test Results Grain-Size Analyses General GEOTECHNICAL ENGINEERING STUDY TALBOT HEIGHTS SINGLE-FAMILY RESIDENCE DEVELOPMENT 16808 AND 16816106TH AVENUE SOUTHEAST KING COUTNY, WASHINGTON INTRODUCTION This report presents the results of the geotechnical engineering study completed by Earth Consulting Incorporated (ECI) for the proposed Talbot Heights Single-Family Residence Development, 16808 and 16816 106th Avenue Southeast, King County, Washington. The general location of the site is shown on the "Vicinity Map," Plate 1. The purpose of this study was to explore the subsurface conditions at the site and, based on the conditions encountered, to provide geotechnical engineering recommendations for developing the site with a single-family residence development Project Description The subject site consists of two parcels that make up the approximately 1.8-acre site, located at 16808 and 16816 106th Avenue Southeast, King County, Washington. We understand it is planned to develop the site with a 15-lot single-family residence development. We anticipate the buildings will be of relatively lightly loaded wood-framed construction with a combination of wood joist and slab-on-grade floors. We anticipate wall loads will be on the order of 2 to 3 kips per lineal foot and column loads will be in the range of 20 to 40 kips. We estimate slab-on-grade floor loads will be up to 150 pounds per square foot (psf). We understand that access to the site will be provided from the east side of 106th Avenue Southeast. The access road will extend approximately 150 feet east from 106th Avenue Southeast to a T-intersection. Two roads will extend from the intersection to the north and south property lines. We anticipate maximum cuts and fills in the range of 10 feet or less will be required to reach construction subgrade elevations within the limits of the site. We understand that stormwater from the site will be disposed of into a stormwater control facility located at the southwest corner of the site. At the time our study was performed, the site and the exploration locations were approximately located as shown on the "Test Pit Location Plan," Plate 2. If the above project criteria are incorrect or change, we should be consulted to review the recommendations contained in this report. In any case, ECI should be retained to perform a general review of the final design. GEOTECHINCAL ENGINEERING Sl\JDY October 29, 2007 E-13050 Scope of Services We performed this study in general accordance with the scope of services outlined in our September 12, 2007, proposal. On this basis, our study addresses the following: • Evaluation of general subsurface conditions and description of types, distribution, and engineering characteristics of subsurface materials • Evaluation of geologic hazards, including site seismicity, slopes, liquefaction, and seismic settlement potential, and recommendations for appropriate mitigation measures • Evaluation of general groundwater conditions and potential impact on design and construction • General recommendations for earthwork, including site preparation, excavation, site drainage • Determination of the seismic design parameters • Evaluation of project feasibility and suitability of on-site soils for foundation support • Recommendations for suitable foundations, including allowable soil bearing capacities, associated settlement estimates, and lateral pressures and resistances • Recommendations for the design of retaining walls • Recommendations for subgrade preparation for floor slab and slab-on-grade support • Recommendations for temporary and permanent slopes • Recommendations for utility support and backfill • Suggestions for pavement sections EARTH CONSULTING INCORPORATED Page 2 GEOTECHINCAL ENGINEERING snJDY October 29, 2007 Suriace E-13050 SITE CONDITIONS The rectangular-shaped site is located along the east side of 106th Avenue Southeast, approximately 900 feet south of the intersection of Benson Road South and 106th Avenue Southeast, King County, Washington. The site is bordered to the north, south and east by single-family residence lots and to the west by 106th Avenue Southeast. The topography of the site is relatively level. The overall elevation change within the site is on the order of 15 feet, sloping down from the northeast to the southwest portion of the site. The gradient throughout the majority of the site is in the range of 4 percent or less and ranges up to 13 percent at the northeast quadrant of the site. The site is vegetated primarily with grass lawns and landscaping shrubs and trees. The northeast quadrant of the site is vegetated with deciduous trees and evergreen trees, with an undergrowth of sword ferns and miscellaneous brush. Subsuriace Subsurface conditions at the site were evaluated by reviewing a geologic map of the site and excavating eight test pits at the site. Geologic Map Review Based on review of the Geologic Map of King County, Washington compiled by Booth, Haugerud and Sacket (2002), the subject site is mapped as glacial till (Qvt). Glacial till is described as a compact diamict of silt, sand and gravel deposited by glaciers. Subsurface Exploration Subsurface conditions at the site were evaluated by excavating eight test pits on October 4, 2007, at the approximate locations shown on Plate 2. The test pits were excavated to a maximum depth of 1 O feet below grade using a rubber-tired backhoe. The test pit logs are included as Plates A2 through A9. Please refer to the test pit logs for a detailed description of the conditions encountered at each test pit location. A description of the field exploration methods is included in Appendix A. The following is a generalized description of the subsurface conditions encountered. At the test pit locations, 4 to 6 inches of topsoil was generally encountered. The topsoil was characterized by its dark brown color and the presence of sod and organic material. Underlying the topsoil at the location of Test Pit TP-2, 3 feet of fill comprised of loose silty sand (Unified Soil Classification SM) was encountered. The fill was characterized by its loose condition and disturbed appearance. Underlying the fill at the location of Test Pit TP-2, 1.5 feet of medium dense brown silty sand (SM) overlying dense glacial till was encountered to the maximum exploration depth of 8.5 feet below grade. The glacial till was comprised of moderately cemented silty sand (SM) with gravel. EARTH CONSULTING INCORPORATED Page 3 GEOTECHINCAL ENGINEERING Sl\JDY October 29, 2007 E-13050 Underlying the topsoil at the location of Test Pit TP-4, very dense glacial till was encountered to the maximum exploration depth of 5 feet below grade. Underlying the topsoil at the remaining test pit locations, 1 to 3 feet of loose to medium dense silty sand with variable amounts of gravel (SM) overlying dense to very dense glacial till was encountered to the maximum exploration depth of 10 feet below grade. Based on the subsurface explorations and our review of the geologic map of the site, the soils encountered in the test pits correspond with the mapped soil unit. Groundwater No groundwater seepage was encountered in the test pits at the time of our exploration, October 2007. Iron oxide staining was commonly observed in the zone between the surficial silty sand and the glacial till encountered in the test pits. The mottling at this location is likely indicative of groundwater percolating through the relatively permeable soils and becoming perched over the relatively impermeable dense glacial till. The contractor should be aware that groundwater levels should not be considered static. Groundwater levels fluctuate depending on the season, amount of rainfall, surface water runoff, and other factors. Generally, the groundwater level is higher in the wetter winter months (typically October through May). Laboratory Testing Laboratory tests were conducted on representative soil samples to verify or modify the field soil classification and to evaluate the general physical properties and engineering characteristics of the soil encountered. Visual classifications were supplemented by grain- size analyses on representative samples. Moisture content tests were performed on representative samples. The results of laboratory tests performed on specific samples are provided at the appropriate sample depth on the individual test pit logs or on a separate data sheet contained in Appendix B. It is important to note that these test results may not accurately represent the overall in-situ soil conditions. Our geotechnical engineering recommendations are based on our interpretation of these test results. ECI cannot be responsible for the interpretation of these data by others. In accordance with our Professional Services Contract, the soil samples from this project will be discarded following completion of this report unless we are directed otherwise in writing. EARTH CONSULTING INCORPORATED Page 4 GEOTecHINCAL ENGINEERING STUDY October 29. 2007 DISCUSSION AND RECOMMENDATIONS General E-13050 Based on the results of our study, in our opinion, construction of the proposed residential development is feasible from a geotechnical engineering standpoint. The proposed buildings may be supported on a conventional spread and continuous footing foundation system bearing on competent native soil or structural fill used to modify site grades. Concrete slab- on-grade floors should be similarly supported. This report has been prepared for specific application to this project only and in a manner consistent with that level of care and skill ordinarily exercised by other members of our profession currently practicing under similar conditions in this area. This report is for the exclusive use of RW Puget Sound Holdings, LLC and their representatives. No warranty, expressed or implied, is made. This report, in its entirety, should be included in the project contract documents for the information of the contractor. Site Preparation and General Earthwork Review of the preliminary site plan indicates site earthwork will consist of installing erosion control measures, stripping the site, grading the site to provide building and access road grades, constructing the stormwater facility, installing underground utilities and drainage, and completing footing excavations for the proposed buildings. If desired, the vegetation at the location of the lots may remain undisturbed during construction of the access roads and stormwater facility to aid in erosion control at the site. Stripping Prior to stripping, on-site erosion control measures consisting of silt fencing and surface water controls should be installed around the perimeter of the site. The building and pavement areas and areas to receive structural fill should be stripped and cleared of surface vegetation, organic matter, existing foundations or pavements, and other deleterious material. Based on the thickness of the topsoil and vegetation cover encountered at the exploration locations, we anticipate a typical stripping depth of 4 to 6 inches. The actual stripping depth should be based on field observation at the time of construction. Root balls from vines, brush, and trees should be grubbed out to remove roots greater than about 1-inch in diameter. The depth of excavation to remove root balls could exceed 2.5 feet below the existing ground surface. Depending on the grubbing methods used, disturbance and loosening of the subgrade could occur during the grubbing process. Soil disturbed during the grubbing process should be compacted in place to the requirements of structural fill. In no case should the stripped or grubbed materials be used as structural fill or mixed with material to be used as structural fill. The stripped materials may be "wasted" on site in non- structural landscaping areas or placed on finished lots as topsoil, or they should be exported. EARTH CONSUL TING INCORPORATED Page 5 GEOTECHINCAL ENGINEERING STUDY October 29, 2007 E-13050 Existing utility pipes to be abandoned should be plugged or removed so that they do not provide a conduit for water and cause soil saturation and instability problems. Following the stripping operation, the ground surface where structural fill, foundations, slabs, or pavements are to be placed should be observed by a representative of ECI. Proofrolling may be necessary to identify soft or unstable areas. Proofrolling should be performed under the observation of a representative of ECI. Soil in loose or soft areas, if recompacted and still yielding, should be overexcavated and replaced with a granular structural fill. The optional use of a geotextile fabric placed directly on the overexcavated surface may also help to bridge unstable areas. ECI can provide recommendations for geotextiles, if necessary. Structural Fill Structural fill is defined as compacted fill placed under buildings, roadways, floor slabs, pavements, or other load-bearing areas. Structural fill should be placed in horizontal lifts not exceeding 12 inches in loose thickness and compacted to a minimum of 95 percent of its laboratory maximum dry density determined in accordance with ASTM Test Designation D1557 (Modified Proctor). The fill materials should be placed at or near their optimum moisture content. In our opinion, the native soils that will be encountered on site can be considered for use as structural fill provided the soil is near its optimum moisture content at the time of placement. The site soils have a relatively high fines content of up to 47 percent passing the U.S. No. 200 sieve, resulting in very moisture sensitive conditions. Moisture conditioning the soils, adding water or aerating, to achieve near-optimum moisture conditions will be difficult. Subsequently, a contingency in the earthwork budget should be included in the earthwork contract for costs associated with importing structural fill. An imported granular structural fill may be a necessary alternative to using the existing site soils for raising site grades, utility trench backfill, and road base fill. Imported soil intended for use as structural fill should consist of a fairly well-graded granular soil with a moisture content that is at or near its optimum moisture content and has a maximum aggregate size of 4 inches. During wet weather conditions or where groundwater seepage is encountered, structural fill should consist of a fairly well-graded granular material having a maximum aggregate size of 4 inches and no more than 5 percent fines passing the U.S. No. 200 sieve. Foundations Based on the results of our study, in our opinion, the proposed building may be supported on a conventional spread and continuous footing foundation system bearing on competent native soil or structural fill used to modify site grades. If loose native soil or existing fill is encountered at subgrade elevation, the loose soil should be compacted to the requirement of structural fill. Alternatively the foundations may extend through the loose soil to suitable bearing soils. We anticipate suitable bearing soils will be encountered between 0.5 and 3 feet below existing grade. EARTH CONSULTING INCORPORATED I GEOTECHINCAL ENGINEERING ST\JDY October 29, 2007 E-13050 Exterior foundation elements should be placed at a minimum depth of 18 inches below final exterior grade for frost protection. Interior spread foundations can be placed at a minimum depth of 12 inches below the top of slab, except in unhealed areas where interior foundation elements should be founded at a minimum depth of 18 inches. Continuous and individual spread footings should have minimum widths of 16 and 18 inches, respectively. With foundation support obtained as described, for design, an allowable soil bearing capacity of 2500 psf may be used for medium dense to dense native soils or structural fill. Loading of this magnitude would be provided with a theoretical factor-of-safety in excess of 3.0 against shear failure. For short-term dynamic loading conditions, a 1/3 increase in the above allowable bearing capacity can be used. With structural loading as expected and provided the above design criteria are followed, total settlement of less than approximately 1 inch is anticipated, with differential settlement of approximately 0.5 inch. Most of the anticipated settlement should occur during construction as dead loads are applied. Horizontal loads can be resisted by friction between the base of the foundation and the supporting soil and by passive soil pressure acting on the face of the buried portion of the foundation. For frictional capacity, a coefficient of 0.30 should be used. Resistance due to passive earth pressure may be computed using an equivalent fluid pressure of 300 pounds per cubic foot (pcf) for footings backfilled with structural fill. These values are allowable values; a factor-of-safety of 1.5 has been included. As movement of the foundation element is required to mobilize full passive resistance, the passive resistance should be neglected if such movement is not acceptable. Unless covered by pavements or slabs, the passive resistance in the upper 1 foot of soil should be neglected. ECI should be retained to observe the foundation subgrade prior to placement of structural fill, forms, or rebar. Retaining Walls Retaining walls should be designed to resist the lateral loads imposed by the retained soils and applicable surcharge loads. Walls that are designed to yield can be designed to resist the lateral earth pressures imposed by an equivalent fluid with a unit weight of 35 pcf. If walls are to be restrained at the top from free movement, the equivalent fluid weight should be increased to 50 pcf. These values are based on horizontal backfill conditions. Surcharges due to backfill slopes, hydrostatic pressures, traffic, structural loads, or other surcharge loads are assumed to not act on the wall. If such surcharges are to apply, they should be added to the above design lateral pressure. The passive pressure, allowable bearing capacity, and friction coefficient previously provided in the "Foundations" section are applicable to the retaining wall design. EARTH CONSULTING INCORPORATED Page 7 GEOTEOIINCAL ENGINEERING ST\JDY October 29, 2007 E-13050 To reduce the potential for hydrostatic pressures to build up behind the walls, retaining walls should be backfilled with a free-draining material extending at least 18 inches behind the wall. The free-draining backfill should consist of either pea gravel or washed rock. A rigid, 4- inch-diameter, schedule 40, perforated PVC drain pipe should be placed at the base of the footing of the wall and should be surrounded by a minimum of 1 cubic foot per lineal foot with pea gravel or washed rock. The pipe should be placed with the perforations down. The remainder of the backfill should consist of structural fill. Slab-on-Grade Floors Slab-on-grade floors may be supported on competent native soil or structural fill. Loose or disturbed subgrade soil must either be compacted to the requirements of structural fill or replaced with structural fill. Slabs should be provided with a capillary break comprised of a minimum of 4 inches of free- draining sand or gravel. In areas where slab moisture is undesirable, a vapor barrier, such as a 6-mil plastic membrane, should be placed beneath the slab. Seismic Design Considerations Earthquakes occur in the Puget Lowland with regularity; however, the majority of these events are of such low magnitude they are not detected without instruments. Large earthquakes do occur, as indicated by the 1949, 7.2 magnitude earthquake in the Olympia area and the 1965, 6.5 magnitude earthquake in the Midway area and the 2001, 6.8 magnitude earthquake in the Nisqually area. There are three potential geologic hazards associated with a strong motion seismic event at this site: ground rupture, liquefaction, and ground motion response. Ground Rupture The strongest earthquakes in the Puget Lowland are widespread, subcrustal events, ranging in depth from 30 to 55 miles. Surface faulting from these deep events has not been documented to date. Therefore, it is our opinion, that the risk of ground rupture at this site during a strong motion seismic event is negligible. Liquefaction Liquefaction is a phenomenon in which soils lose all shear strength for short periods of time during an earthquake. Groundshaking of sufficient duration results in the loss of grain-to- grain contact and rapid increase in pore water pressure, causing the soil to behave as a fluid. To have a potential for liquefaction, a soil must be cohesionless with a grain-size distribution of a specified range (generally sand and silt), it must be loose, it must be below the groundwater table, and it must be subject to sufficient magnitude and duration of groundshaking. The effects of liquefaction may be large total and/or differential settlement for structures founded in the liquefying soils. EARTH CONSULTING INCORPORATED Page 8 GEOTECHINCAL ENGINEERING sruov October 29, 2007 E-13050 In our opinion, the liquefaction potential at this site is low to negligible. This conclusion is based on the dense soils encountered at the test pit locations and the lack of a shallow groundwater table. Ground Motion Response The 2003 International Building Code® (/BC) regulations contain a static force procedure and a dynamic force procedure for design-base shear calculations. Based on the encountered soil conditions, it is our opinion Site Class C, "Very dense soil or soft rock," as defined in Table 1615.1.1 of the /BC, should be used to characterize the site soils. In accordance with Section 1615.1.2 of the /BC, seismic values, Sms = 1.218 and Sm1 = 0.642 should be used for design. Excavations and Slopes The following information is provided solely as a service to our client. Under no circumstances should this information be interpreted to mean that ECI is assuming responsibility for construction site safety or the contractor's activities; such responsibility is not being implied and should not be inferred. In no case should excavation slopes be greater than the limits specified in local, state (WISHA), and federal (OSHA) safety regulations. Based on the information obtained from our subsurface exploration, the loose fill and medium dense surficial soils encountered in the test pit locations would be classified as Type C by WISHA/OSHA. Temporary cuts greater than 4 feet in height in Type C soils should be sloped at an inclination of 1.5H:1V (Horizontal:Vertical). The underlying dense silty sand encountered in the test pits would be classified as Type A by WISHA/OSHA and should be sloped at an inclination of 0.75:1V. If seepage is encountered in the excavation, the soils should be classified as Type C and cut accordingly. An ECI representative should observe temporary excavations to verify soil and groundwater conditions and the soil type. If slopes of the above inclinations or flatter cannot be constructed, temporary shoring may be necessary. Shoring will help protect against slope or excavation collapse and will provide protection to workers in the excavation. If additional temporary shoring is required, we will be available to provide shoring design criteria. Permanently exposed slopes should be seeded with an appropriate species of vegetation to reduce erosion and improve stability of the surficial layer of soil. EAR'lli CONSUL TING INCORPORATEO Page 9 GEOTECHINCAL ENGINEERING STUDY October 29, 2007 Site Drainage E-13050 During construction, the site must be graded such that surface water is collected and tightlined to an appropriate drainage facility. Water must not be allowed to stand in areas where buildings, slabs, or pavements are to be constructed. Loose soil surfaces should be sealed by compacting the surface to reduce the potential for moisture infiltration. Final site grades must allow for drainage away from the building foundation. The ground should be sloped at a gradient of 2 percent in paved areas and 3 percent in landscaped areas for a distance of at least 10 feet from the buildings. Footing drains may be installed around the perimeter of the building at or just below the invert of the footing, as shown on the "Typical Footing Subdrain Detail," Plate 3. Under no circumstances should roof downspout drain lines be connected to the footing drain system. Roof downspouts must be separately tightlined to discharge. Cleanouts should be installed at strategic locations to allow for periodic maintenance of the footing drain and downspout tightline systems. Utility Support and Backfill The site soils should generally provide adequate support for utilities. Where loose soils or unstable conditions are encountered, remedial measures, such as compacting subgrade soils exposed in the trench bottom, may be required. In addition, caving of trench walls should be anticipated in trench excavations in the loose soil or where seepage is encountered in the excavation. Utility trench backfill is a primary concern in reducing the potential for settlement along utility alignments, particularly in pavement areas. It is important that each section of utility line be adequately supported in the bedding material. The material should be hand tamped to provide support around the pipe haunches. Fill should be carefully placed and hand tamped to approximately 12 inches above the crown of the pipe before heavy compaction equipment is brought into use. The remainder of the trench backfill should be placed in lifts having a loose thickness of less than 12 inches and compacted to the requirements of structural fill. Suggested Pavement Sections The adequacy of site pavements is related in part to the condition of the underlying subgrade. To provide a proper subgrade for pavements, the subgrade should be treated and prepared as described in the "Site Preparation and General Earthwork" section of this report. The pavement subgrade should be compacted to 95 percent of the maximum dry density per ASTM D1557 (Modified Proctor). It is possible that some localized areas of soft, wet, or unstable subgrade may still exist after this process. Additional subgrade preparation, such as overexcavation of the soft soil and replacement with crushed rock, may be needed. The recommended pavement sections assume the pavement subgrade soils will be compacted and in a firm and unyielding condition. Proofrolling should be performed to identify soft, unstable areas. Proofrolling should be performed using a fully loaded dump truck and should be observed by a representative from ECI. EARTH CONSULTING INCORPORATED Page 10 GEOTECHINCAL ENGINEERING STIJDY October 29, 2007 E-13050 Assuming a properly prepared subgrade, either of the following pavement sections for lightly loaded areas is suggested: • 2 inches of asphalt concrete (AC) over 4 inches of crushed rock base (CRB) material • 2 inches of AC over 3 inches of asphalt treated base (ATB) material The above pavement sections may be superseded by minimum sections required by King County. These pavement sections may need to be modified based on anticipated traffic loads and frequency. Pavement materials should conform to WSDOT specifications. Class B asphalt mix should be used. LIMITATIONS Our recommendations and conclusions are based on the observed site conditions, selective laboratory testing and engineering analyses, the design information provided for us, and our experience and engineering judgment. The conclusions and recommendations are professional opinions derived in a manner consistent with that level of care and skill ordinarily exercised by other members of the profession currently practicing under similar conditions in this area. No warranty is expressed or implied. The recommendations submitted in this report are based on the data obtained from the test pits. Soil and groundwater conditions between test pits may vary from those encountered. The nature and extent of variations between the exploratory locations may not become evident until construction. If variations do appear, ECI should be requested to reevaluate the recommendations of this report and to modify or verify them in writing prior to proceeding with the grading. Additional Services As the geotechnical engineer of record, ECI should be retained to perform a general review of the final design and specifications to verify that the earthwork and foundation recommendations have been properly interpreted and implemented in the design and in the construction specifications. ECI should also be retained to provide geotechnical engineering services during construction. This is to observe compliance with the design concepts, specifications, or recommendations and to allow design changes in the event subsurface conditions differ from those anticipated prior to the start of construction. EARTH CONSULTING INCORPORATED Page 11 .. 4t·h:qJt !-ts,. ~ .,.. .. ~ ~! ... $~ ... RR ·-. ,~ . ~~ SW ' 7TH ~ ;5 ~. " u., l ""> > ~< < 0 < ~ I t Cl )> -~ 0:: r- i9ROO,r i,l}lll .. r-~,.,,,,, l'T"I ~ SlA.!'7U lt!Jf'''., -< ....... a. SW 19TH ST s QIH ~~ FS PANTHER v. ~ CRECK l/£TUl()j 3 V) SI/ 23RD ST s >-u.J ...J > ...J < <( > SW 27TH ST RE/fTON llfTLANDS -r SW 29TH ST ~ \ :z -< V) SW 30TH ST SIi 3JRD SI > < SI/ 34TH ST R(Nr/j/1 C> l SIi ~ ST!I WETU.~'OS -' ST w J ... SW 39TH ST c§ V) ~~ ... ~ SW ~: 41ST ST I Map © Rand McNally & Company, R.L.07-S-23, reproduced with permission. It is unl awful to fu rther copy or re produce without separate permission from Rand McNally. A NORTH NOT TO SCALE :: ~;'sn, ST l61H ST ,, I 162ND ::C :; 27Tll ST :~ SE 164TH ... V) "" ;; V) > < :,: l 16 >-g; V) ,- " ~ - ~ .... ~/. y~ or ~ FS ~ RO SE -w .., ::, r:: V):. .; .. co > 1 "' =: < - EARTH CONSULTING INCORPORATED iS ~ ;. t f. VICINITY MAP TALBOT HEIGHTS r ~ u., V') ::,. < KING COUNTY, WASHINGTON Tfl > ST ~ i': w V V) ST ~[ Jb5TH ~q > < r :::,. "' < DRWN. DNM PROJ. NO . 13050 CHKD. SJS DATE 10/22/07 PLATE 1 SE 166TH ST -----I -l I ;, O(f,h , • ... s,,1 ,w, ' I --·---"' ' '"'· ' ,, TP-61 ' -•-B .. 1 ' I ;'•;., •,I 4 ,:: '< ' ,:~ c, ~ h ' 9 1 TP-5 -•-I " -·----' -,'<,--~' 3 ' 4 • " ~ 6 10 ,.~ :~ s· <.<''., ,• .l.6W '• 4,P!, S< ··- iii TP-71 I/! -•-~ ' 11 <t. TP-81 ~ . .i,--_./- ~ I 1TP-4 •-.._______.=,L_ ,., " I -•-I 1l ' ' '!".'' TP-2 ,. : y 'I~ -•-' 13 I ,, , .. ! TRACT J, ' 7 14 C n-' TP-3 l'L)J'.' •.:': ::r ,. _J - I TP-1 -•--•-(1sj I I ? c',c , :.Ju <> " n -------- ' ,, .. ,. i SE i72f\O ST REFERENCE: DUNCANSON COMPANY, INC., PROGRESS DRAFT 9/5/07 LEGEND C, TP-1 EARTH I Approximate location of ECI test pit, CONSULTING -•-I Proj. No. E-13050, October 2007 INCORPORATED A TEST PIT LOCATION PLAN TALBOT HEIGHTS KING COUNTY, WASHINGTON NORTH 0 60 DRWN. DNM PROJ. NO. 13050 APPROXIMATE SCALE IN FEET CHKD. SJS DATE 10122/07 PLATE 2 4 INCH MIN. DIAMETER PERFORATED PIPE r.:'.:':?t:::::.:::,•;J ~ 0 2 INCH MIN. I 41NCH MAX. LEGEND Surface seal; native soil or other low permeability material Washed rock or pea gravel Drain pipe; perforated or slotted rigid Schedule 40 PVC or SDR 35 pipe laid wtth perforations or slots facing down; tight jointed; with a positive gradient. Do not use flexible corrugated plastic pipe. Do not tie building downspout drains into footing lines. SLOPE TO DRAIN 0 12 INCH MIN. z ~ I (.) ~ "' 2 INCH MIN. SCHEMATIC ONLY-NOT TO SCALE NOT A CONSTRUCTION DRAWING C, earth Consulting Incorporated TYPICAL FOOTING SUBDRAIN DETAIL TALBOT HEIGHTS KING COUNTY, WASHINGTON DRWN. DNM PROJ. NO. 13050 CHKD. SJS DATE 10/22/07 PLATE 3 APPENDIX A FIELD EXPLORATION E-13050 Earth Consulting Incorporated (ECI) performed the field exploration on October 4, 2007. Subsurface conditions at the site were explored by excavating eight test pits to a maximum depth of 10 feet below existing grade. The test pits were excavated by Aikins' Excavating using a tracked excavator. Approximate test pit locations were estimated by pacing from site features depicted on a site plan. The test pit elevations were estimated based on topographic data depicted on the site plan. The locations and elevations of the test pits should be considered accurate only to the degree implied by the method used. These approximate locations are shown on Plate 2. The field exploration was continuously monitored by Mr. Steve Scharf, a representative from our firm, who classified the soils encountered, maintained a log of each test pit, obtained representative samples, and observed pertinent site features. The samples were visually classified in accordance with the Unified Soil Classification System (USCS), which is presented on the "Legend," Plate A 1. Representative soil samples were collected and returned to our laboratory for further examination and testing. Logs of the test pits are presented on Plates A2 through A9. The final logs represent our interpretations of the field logs and the results of the laboratory examination and tests of field samples. The stratification lines on the logs represent the approximate boundaries between soil types. In actuality, the transitions may be more gradual. MAJOR DIVISIONS Coarse-grained soils Moro than 50% material larger than No. 200 sieve size Fine-grained soils More than 50% material smaller than No. 200 sieve size Gravel and gravelly sods More than 50% coarse fraction retained on No. 4 Sieve Sand and sandy soils More than 50% coarse fraction passing No 4 Sieve S'ilts and clays Silts arid clays Highly organic soils Topsoil fill Clean grc;vels (little or no f1rics) Gravels with f1r1cs (appreciable amount of fines) Clean sand (little or no tines) Sands with t1nc-:s (appreciable an1o'~r·l of fines\ Liquid l:mt less thar~ s,:-:, Liqu·1d l1n1i; greate1 them 50 GRAPH SYMBOL LETTER SYMBOL •••••••• , I, I, I. I GP / .... _ •• /// gp ',i' GM / .1.1;11.1 // ~ • I• '+I• / gm CH ch PT // ••• ,..· pt TYPICAL DESCRIPTION Well-graded gravels, gravel-sand mixtures. little or no fines Poorly-graded gravels. gravel-sand mixtures, little or no fines Silty gravels, gravel-sand-silt mixtures Clayey gravels, gravel-sand-clay mixtures Well-graded sands. gravelly sands, little or no fines Poorly-graded sands, gravelly sands, little or no lines Silty sands, sand-silt rrnxtures Clayey sands, sand-clay mixtures Inorganic sills and very f'1r1e sands. rock !lour, silty-clayey fine sands, clayey silts wiH1 slight plasticity Inorganic clays of low to medrum plasticity, gravelly clays, sandy clays, silty clays, lean clays Organic silts and organic silty clays of low plasticity Inorganic silts, micaceous or d1atomaceous fine sand or silty soils Inorganic clays of high plasticity, fat clays Organic clays of medium to high plasticity, organic sills Peat, humus, swamp soils with high organic contents Humus and duff layer Highly varic1ble conslituents The discussion in the text of this report is necessary for a proper understanding of the nature of the material presented in the attached logs. Dual symbols are used to indicate borderline soil classification. C qu w p pcf LL Pl C, TORVANE READING, tsf PENETROMETER READING, tsf MOISTURE, % dry weight SAMPLER PUSHED SAMPLE NOT RECOVERED DRY DENSITY, lb. per cubic ft. LIQUID LIMIT, % PLASTIC INDEX Earth Consulting Incorporated I 2" O.D. SPLIT SPOON SAMPLER 2.4" LD. RING OR SHELBY TUBE SAMPLER WATER OBSERVATION WELL DEPTH OF ENCOUNTERED GROUNDWATER DURING EXCAVATION SUBSEQUENT GROUNDWATER LEVEL WITH DATE LEGEND -A1 Test Pit Log Project Name: Talbot Heights -Job No. I Logged by: 13050 SJS f-------·-· -' ---·---- Excavation Contractor: Aikins' Excavating ~------------------ ___ 1 ______ T _____ .lsh;et--~- . Date: Test Pit No.: , 10/4/07 TP-1 ·------f"Approx. Gro~nd Surface Elevation:-- 420' _____ . ____ ] __________ - Notes: General Notes 1 I u -¢l I O I Surface Conditions: I w t E t . a.I ~ _oE I Depth of topsoil and sod 4"; grass lawn (%) I ~ [ 0(1) it § I " -I CJ "' "' :, "' I 11 ljll · SM ' Brown silty SAND with gravel, medium dense, dry 1 iliillll 1tl I I Ii f 11111 2 1~ I -iron oxide staining I lttHlffi i---i--SML--------· ---------------- 1 99 11111111 3 J--I I Light brown silty SAND with gravel, dense, moist (Glacial Till) -iron oxide staining -moderate cementation I 11111111 4 ~1 I I ii 11111 5 Lf I occasional cobble : 111111 6t=-1 i I \l1lll 1 ~__j I 11 1111 l_ J 1 1 111 ! 111 8 911-_=i_l i 111111 I · -46.7% fines i 12.4 11 . . . I I I I µlllUll 10 1--r __ T I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I : I I I I -----------------·----------- Test pit terminated at 10' below existing grade. No groundwater encountered during excavation. s I I i ! I I I i I 01-----~---~~~~--~-----~---------------------{ g Test Pit Log s Earth Consulting Incorporated Talbot Heights ls' King County, Washington in1--------r---------r---------+-----------------.------{ i" I I l it Proj. No. 13050 Own. DNM Date 10/22/07 Checked SJS Date 10/22/07 Plate A2 Subsurface conditions depicted represent our observations at the time and locat1on of thrs exploratory hole, modified by engineering tests, analysis and judgment. They are not necessarily representative of other times and !ocations. We cannot accept responsibility for the use or interpretation by others of information presented on this Jog. ~ p -~ el ~ 0 '-' u w a: '-' 0 ~ 0 ~ Test Pit Log Project Name: Talbot Heights -I Job No. Logged by: 13050 SJS Excavation Contractor: T Date: 10/4/07 I Sheet of ' 1 1 -] -Test Pit No.i ___j_ TP-2 ----- I Approx. Ground Surface Elevation: 422' Aikins' Excavating ~· --------------------------l Notes: General Notes u -I ' V (/) 0 w f..2't~ Q_ l) D (%) roEIDLL E "' E <!) if; D • :::, >- (/) (/) Surface Conditions: Depth of topsoil and sod 4"; grass lawn Brown silty SAND, loose, moist (Fill) ~ 11-SM ;l; 2t=J 24.6 .XM2 t ~t Brown silty SAND, medium dense, moist 10.6 ;: , 6 _ 1 -iron oxide staining mo I I~ JO . J_ ·OmOeca<eceme,<a»oo . 1 1 I Test pit terminated at 8.s' below-existing grade.-No groundwater- encountered during excavation. I : I I I Test Pit Log '-' 'l Earth Consulting Incorporated Talbot Heights I,: King County, Washington mt---------.---------,----------+---------,----------,------- " Proj. No. 13050 Own_ DNM I Date 10/22/07 Checked SJS I Date 10/22/07 I Plate A3 Subsurface cond1t1ons depicted represent our observations at the time and location of this exploratory hole, modified by eng1neenng tests, analysis and judgment. They are not necessarily representative of other times and locations. We cannot accept responsibility for the use or interpretation by others of information presented on this log. Test Pit Log Project Name: of 1 I Sh;et Talbot Heights >--------------------~------~ Job No. __Dgged by: ~itNo.: " 0 ~ c ~ m ~ I Date: 13050 SJS i 10/4/07 T -3 - Excavation Contractor: I Approx. Ground Surface Elevation: _Aikins' Excavating 425' ---------- Notes: Io -.c ~ I <f) 0 I Surface Conditions: Depth of topsoil and sod 4"; grass lawn I·-Q General w .c -" -Q_ u -" Notes , "-E ~hi E <fl E (%) !::' >, O ro :::, if; ('.) <f) <f) I!'' ~ SM Brown silty SAND with gravel, medium dense, moist ; I 1 ------------ ' SM Light gray silty SAND with gravel, very dense, dry (Glacial Till) 2tl I -moderate to strong cementation 31-79 I -~ 'illl~ •. i :~~--------------- Test pit terminated at 5' below existing grade. No groundwater i encountered during excavation. I I I I I ' ' I Test Pit Log Earth Consulting Incorporated Talbot Heights King County, Washington Proj. No. 13050 Own. DNM I Date 10/22/07 Checked SJS \ Date 10/22/07 I Plate A4 Subsurface cond1t1ons depicted represent our observations at the time and location of this exploratory hole, modified by engineering tests, analysis and judgment. They are not necessarily representative of other times and locations. We cannot accept responsibility for the use or interpretation by others of information presented on this log. Test Pit Log Project Name: ~ot Heights _ ~~ ___ _ Job No. I Logged by: ____13050 _ ______l_ SJS -~--~ Excavation Contractor: ~ins' Excavating_ ___ ___ __ Notes: General Notes "'o I o i I "' >, ::, "' .1 Sheet of __L_1 ___ 1 -- : Da11~14107 -=-I Te;~~No~---------- LApprox. Ground Surface Elevation: 428' ------------·-------------~ Surface Co11d;1;ons: Depth of topsoil and sod 4"; sword ferns, misc. brush Light gray silty SAND with gravel, very dense, dry (Glacial Till) -moderate to strong cementation -becomes moist Test pit terminated at 5' below existing grade. No groundwater encountered during excavation. Test Pit Log " s Earth Consulting Incorporated Talbot Heights ti: King County, Washington mi-------~-------~-------1-------~--------~-------1 ;:; Proj. No. 13050 Dwn. DNM \ Dale 10/22/07 Checked SJS \ Dale 10/22/07 \ Plate A5 Subsurface cond1t1ons depicted represent our observations at the time and focat1on of this exploratory hole, modified by eng1neenng tests, analysis and judgment. They are not necessarily representative of other times and locations. We cannot accept responsibility for the use or interpretation by others of information presented on this log. Test Pit Log Project Name: Talbot Heights ~Job No.--!Logged b~ ·---- ~13050 --LJJ.§__ ~ -. _ Excavation Contractor: ~ Aikins' Ex.cavating _____ ·-· __ Notes: I Sheet of r:--~· -·-----,~ -_.Li~1 - I uate: I Test Pit No.: _j 10/4107 ----[ TP-5~ ------·-- !Approx. Ground Surface Elevation: I 435' ---·-----·--·----------- General Notes (/} o ) Surface Conditions: u .0 I Depth of topsoil and sod 6"; sword ferns, misc. brush <JJ E :, ;;, II 11111fl .j 1 SM : I 111111 2Fl I I 10 · 2 ~llill 3f-l SM - I 1111.11 1 11. 4}1 I I Iii Iii! sr-1 I I 10.0 11111111 6 £ -I I I 111111111 1 i ~ 1 I -lil ----t- i I I I I : I I I I I I I I I I I I I I i I I I I I I I I ! I I I I : I i I I : I I I I ! I 1 I I : Brown silty SAND, medium dense, moist -contains gravel -21.3% fines -----------·------·-------- Light brown silty SAND, dense, moist (Glacial Till) -iron oxide staining -contains gravel -moderate cementation Test pit terminated at 7.5' below existing grade. No groundwater encountered during excavation. ; ! I I ! i 01------~-~---~-~---------,,-----------------------1 g Test Pit Log § Earth Consulting Incorporated Talbot Heights ii: King County, Washington ~1-----------,-------,---------,1---------,---------.-------1 ii; Proj. No. 13050 Dwn. DNM I Date 10/22/07 Checked SJS I Date 10/22/07 I Plate A6 Subsurface cond1t1ons depicted represent our observations at the time and location of this exploratory hole, mod1f1ed by engineering tests, analysis and judgment. They are not necessarily representative of other times and locations. We cannot accept responsibility for the use or interpretation by others of information presented on this log. Test Pit Log Project Name: j Sheet of Talbot Heights 1 1 Jo~ ;;50 I Lo~~~ by -------- I - Date: Test Pit No.: 10/4/07 TP-6 --- Excavation Contractor: I Approx. Ground Surface Elevation: Aikins' Excavating 430' r---------------------I ----- b '-' 0 w '-' g " a. t;; I" a; Notes: u-ID (J) 0 Surface Conditions: Depth of topsoil and sod 6"; misc. ground cover ·-0 t ..... General w .c -" o_ () -" Notes o. E ID U.. E <JJ E (%) ~ >, 0 ro ::, in (9 U) (J) ' ' '~ SM Brown silty SAND with gravel, medium dense, dry I :t_ __ f .. -root mass at 2.5' -'--;-----,-' ----------------------,fd SM Light brown silty SAND with gravel, dense, moist (Glacial Till) 6.5 -moderate cementation ,, ' sf-, lhlill 11 6r' -becomes very dense; strong cementation 9.7 ' i ----------------~--- Test pit terminated at 6-5' below existing grade. No groundwater I encountered during excavation. I . I Test Pit Log Earth Consulting Incorporated Talbot Heights King County, Washington Proj. No. 13050 Dwn. DNM j Date 10/22/07 Checked SJS I Date 10/22/07 I Plate A7 Subsurface cond1t1ons depicted represent our observations at the time and location of this exploratory hole, modified by engmeenng tests, analysis and judgment. They are not necessarily representative of other times and locations. We cannot accept responslbility for the use or interpretation by others of information presented on this log. <!) g c ~ ~ w I" > m Test Pit Log Project Name: 1 Shrt of Talbot Heights 1 Job No. I Logged by: i Date: ! Test Pit No.: 13050 SJS i 10/4/07 =-1 TP-7 ' ------ Excavation Contractor: Approx. Ground Surface Elevation_: Aikins' Excavating 425' --·------ Notes: 101£ 2 U) 0 ! Surface Conditions: Depth of topsoil and sod 4"; grass, misc. brush General w a.E a.....; E () .0 Notes (%) ro W LL UJ E <3;};0 ~ ::, >, U) f---·· SM Brown silty SAND with gravel, loose to medium dense, moist ' 1 ··- ''1 '~ sMI I 'i :LJ SM -··-.----- Light brown silty SAND with gravel, dense, moist (Glacial Till) :! -moderate cementation 6.8 :1q:, 5-~ 6 f-1 7 ~ -1 -becomes very dense _,, ---·---· --·------··-----··----r -Test pit terminated at 7 .5' below existing grade. No groundwater I encountered during excavation. I I I I I I I ! ! ! I Test Pit Log Earth Consulting Incorporated Talbot Heights King County, Washington Proj. No. 13050 Own. DNM I Date 10/22/07 Checked SJS j Date 10/22/07 I Plate A8 Subsurface cond1t1ons depicted represent our observations at the time and locatron of this exploratory hole, modified by engineennQ tests, analysis and judgment. They are not necessarily representative of other times and locations. We cannot accept responsibility for the use or interpretation by others of information presented on this log. ~ ;; "' ~ ~ 0 <!) u w " <!) 0 ~ 0 ~ Test Pit Log Project Name: Talbot Heights ~-----~ -------------- Job No. ___1· Logged by: 13050 SJS --------------- -------------i---= ----J Sh;et ~f -- Date: I Test Pit No.: I 10/4/07 , ____ --TP-8 ---------------- Excavation Contractor: prox. Ground Surface Elevation: Aikins' Excavating ~--------------·----420' ------_ __j_ -··---------------- Notes: General Notes I I Q -1' • I w I t _g t . a.I I (%) r:i [ ~ it ~ 0 I Surface Conditions: <J)-" ll E <J) " Depth of topsoil and sod 4"; grass lawn c,"'I "' ' I :, <J) i I 111111111 t ----1 SM I I illillill 1 j I , illl!lill 2 t-l I 118.8 ~Ii 3t PM-I I 11.li_ll_l_ll __ 4 ~1 I I 9 B I I -moderate cementation I -11u11rn 5 1 =-I __ _ _ , I 1_ 1 I !~~~tgt~~~~i~~;Tndg a~}c~~~(i~';,w existing grade. No groundwater I I ' I I ! I I I I I I I I I ! I ! I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I ! I ! ! I I I I I I I I I I I I I I I I I I I ! ' I I I I I I Reddish brown silty SAND with gravel, loose, moist Light brown silty SAND with gravel, dense, moist (Glacial Till) - <!) Test Pit Log Talbot Heights s Earth Consulting Incorporated ii: King County, Washington ti1-----------------------+---------------------l i" I I I I ;;; Proj, No. 13050 Dwn. DNM Date 10/22/07 Checked SJS Date 10/22/07 Plate A9 Subsurface cond1t1ons depicted represent our observations at the time and location of thrs exploratory hole, modified by engtneenng tests, analysts and judgment. They are not necessarily representative of other tirnes and locations. We cannot accept responsibility for the use or interpretation by others of information presented on this log. APPENDIX B LABORATORY TEST RESULTS E-13050 Particle Size Distribution Report J; J; s : ~.s;s.s~g, & ~ ~ei iii& 1oor-7:--r,-i:\:n-,·~~l·,..,.~:-{:l,;;;"",.J::';-,-i,rrrr-r.:'T'T-t---rii:1rrT'l~'.j,1-,"7:"T""7:~~:rn~:rrT"T"rr-T"--rrrrri-i--ir--r--1 90: : i:J,,,· X N: : 1: I : : : : : : I I I t I r-,:;i.. ;t I I I I I I I I I I : N.I I I I I 601-.1' --H-4,,, i++--JL' +.1' --f!'-+--J!f-Pt,.,l,-f!-' ++-f---; : \ I: : \ : : \ : 1: ~ 1: :1, : I / ! I I I I I I f 1...... 11 ( \I I I I I J II I t I I I I....._.._ 11 I / / I 70f-->---+t+t-~-l<-+<--l>---<--+t-!rt1-l<-·1-1"'::tl----l1'1-t-t-t-,t--t-'l.+--+--->Hi'ti-t-t-t-t-----.Jttt-J-t--t--t---t---i : : ]: : : : : : ' I/: : ri I : : a::: I I i; : 1, : : : ~JI I :I ,:I : : UJ aol-..+' -4+1\'H+++;-.c~...+-1\H-l+-1\-1-+---l---~d-1+.;t' -1-++~-it+-l+t-H-+--l-+--t+-ft-H+-t-+----i Z 1 : 1: : : /: 1: ~I 1 : ~,,' 1: U: I l I / ! I I I ,: rtl. '-.: I I L-I I \l I I I ! ll I~ I I Z~ so1--~-+1YL/+1--tL-1~-/L-'--l'r+t-r-/Lt--t----t-·---l¥lcl+~~f.J-+~--"1~++++--+----l--4+H-H++--,--i w : : : : / : : 1: : :, : : ; ~ : : : : : \ : : : : \t : : UJ 40 l-~-H-hl-t-1-t.-<~-lr-.-<ri+++-lr+-+--~ Q_ I I II ! I I ! 11 I I I I I I I 30 ,_.,.: -+t-H: -+-+--> 11:C..,r'-: -!': __ ,,_' -!',: H-r+_,1,.: -+--+---, : : li : : : : 1: I I I I I I I I \"' ' ' I I I I I I I I ' ' 201-->---ti-1<+-i-,1--t'--l~-/L~--t>t-t-++-/Lt--t---t·· --J->4++-+-•i-+---1-k-'f+t~'-t-+-t-+---H-H++-+--t--r----t 0 D I I I I I I I I I I I I I I I I I I I I I I I I I I I ! I I J I r / I I J 101--i'--Hctr' I+++' +.;.'-.Ji'--;.' -i;'rt-H-ir' +-+-+---H;i' H-H--rr' -,c.;'. -+--i .'-.;,' l+I~' l+++-+-,---;+t+t-"H-t--+---1 ' ' 0 ' 200 100 % COBBLES I I I I / I I / I f I I ! I I I I I I II I I I I I I I 10 1 GRAIN SIZE -mm % GRAVEL %SAND %SILT %CLAY 6.0 47.3 46.7 23.5 55.2 21.3 SJEVE inches ... PERCENT FINER SIEVE PERCENT FINER IS' 3/4" 3/8 11 >< >< 0 100.0 100.0 95.9 0.156 D 100.0 87.6 83.3 GRAIN SIZE 0.837 0.141 COEFFICIENTS number '"" #4 #8 #16 #30 #50 #100 #200 0 94.0 92.6 90.8 87.6 75.4 59.1 46.7 D 76.5 69.8 62.8 56.6 44.4 31.0 21.3 ' '1 '1 0.01 uses AASHTO SM SM SOIL DESCRIPTION 0 TP-1; 9' -SM PL Light brown silty SAND; 12.4% moisture D TP-5; 2.5' -SM 0.001 LL Brown silty SAND with gravel; 102% moistu« REMARKS: 0 Sampled by SJS on 10/05/07. Tested by MS. 0 Sampled by SJS on 10/05/07. Tested by MS. Revie~ ~d .... --- o Source: Sample No.: TP-1 Sample No.: TP-5 Elev./Depth: 9' Elev1Dep1h: 2.5' ¥WI I t) ' 'I D Source: Earth Consulting, Inc. Bellevue, Washington Client: RW Puget Sound Holdings, LLC Project Talbot Heights Proieci No.: E-13050 .AtufQ'',dt.e_:.,..,.+,""""' Abe H~rnanA• uiooratwy Mam er Fi<lure Bl 4 Copies to: DISTRIBUTION E-13050 Mr. Russ Hibbard RW Puget Sound Holdings, LLC 2011 South 341st Place Federal Way, Washington 98003 CONSOLIDATED ENGINEERING LABORATORIES HEADQUARTERS 2001 Crow Canyon Road, Suite 100 San Ramon, CA 94583 Telephone (925) 314-7100 Facsimile (925) 855-7140 e-mail: INFO@celhq.com web site: www.cel-qa.com HONOLULU, HAWAII PO Box 23140 Honolulu, Hawaii 96823-3140 Telephone (808) 864-5778 Facsimile (808) 521-8508 MODESTO 5466 Pirrone Road MEMBERS OFTHE CONSOLIDATED GROUP l Walla Walla *Cascade ~ MATERIALS TESTING & INSPECTION HEADQUARTERS 2791 S. Victory View Way Boise, ID 83709 Telephone {208) 376-4748 Facsimile (208) 322-6515 e-mail: mti@mti-id.com web site: www.mti-id.com CASCADE, ID.AHO 110 E. Pine Street Cascade, ID 83611 Telephone (208) 382-5282 IDAHO FALLS, IDAHO 1230 North Skyline Drive, #C Idaho Falls, ID 83402 Telephone (208) 529-8242 Facsimile (208) 529-6911 Salida, CA 95368-8200 Telephone (209) 543-1740 Facsimile (209) 543-17 48 L-------------- Ontario * ldlho Falls * Headquarters -e;se * Pocatello Twin Falls -L TWIN FALLS, IDAHO 304 Blue lakes Boulevard Twin Falls. ID 83301 Telephone (208) 733-5323 Facsimile (208) 733-5323 OAKLAND 534 23rd Avenue Oakland, CA 94606-5307 Telephone (510) 436-7626 Facsimile (510) 436-7699 SACRAMENTO 950 Riverside Parkway, Suite 60 West Sacramento, CA 95605-1501 Telephone (916) 617-2448 Facsimile (916) 617-2459 SALT LAKE CITY, UTAH 2130 S. 3140 W., Suite C Salt Lake City, UT 84119-1284 Telephone (801) 972-8200 Facsimile (801) 972-8272 SANTA ROSA 7757 Bell Road Windsor, CA 95492-8519 Telephone {707) 838-1113 Facsimile {707) 838-1114 SUNNYVALE 1010 Morse Drive, Suite 18 Sunnyvale, CA 94086-1607 Telephone (408) 752-8960 Facsimile {408) 752-8963 -ERJ.:RHARTIU.VJTW- -CONSVLTA.\/TS HEADQUARTERS 1031 Segovia Circle Placentia, CA 92870-7137 Telephone (714) 632-5555 Facsimile (714) 632-0855 m US Amr, Corps ofEngmeerae 1 ~-1~ Sacr mento Santa Rosa Heaclqua rs -San Ramon J Oakland Sunnyvale Modes D ~ Honolulu "' 'µ 0 f--------- * Headquarte -Moreno Valley Headquarters -lacentia "Partners in Quality" Amtrican Col'lcre~ lnstilute' • ~AV AASHTOR18 POCATELLO, IDAHO 450 East Day Street Pocatello, ID 83201 TelephOne (208) 233-9500 Facsimile (208) 233-9900 ONTARIO, OREGON 110 SE 2nd Avenue Ontario, OR 97914 Telephone (541) 889-3602 Facsimile (541) 889-3605 WALLA WALLA, WASHINGTON 800 A Street Walla Walla, WA 99362 Telephone (509) 526-2573 Facsimile (509) 526-2576 EARTH CONSULTING INCORPORATED BELLEVUE, WASHINGTON 1805 1361h Place NE #201 Bellevue, WA 98005 (425) 643-3780 Facsimile (425) 746-0860 web site: www.eci-mti.com -~tfr{~lf/! -&ff.\""//Nr;/N(" ........._ HEADQUARTERS 22620 Goldencrest Drive Suite 114 Moreno Valley, CA 92553-9033 Telephone (951) 697-4777 Facsimile (951) 697-4770 web site: www.uit-inc.us ,:, if:1 ASCE Talbot l11gfli,inds Preliminary Technical Information Report Talbot Highlands Prcrarcd: J\pril 2, 2008 DC'! Project: 07764 Duncanson Company, Inc. 145 SW 155'" .'itrcct, Suite 102 Scat11e, Washington 98166 (206) 244-4141 DEVELOPMENT PLANNING CITY OF RENTON APR 2 2 2008 RECEIVED D[] 077M Table Of Contents 1. Project Overview figure 1.1 -Tcchnirnl Information Report Worksheet Figure 1.2 -Vicinity \fap Figure I J -Basin Map Figure 1.4-SCS Soil Survey Map 2. [Preliminary] Conditions and Hcquirements Summary 3. Offsite Analysis Offsitc Analysis Drainage System Table Figure 3.1 -OITsitc Analysis Map Figure 3.2 -Critical Areas IVfap 4. Runoff Control and Water Quality Facility Analysis and Design KCSWDM Table 3.5.21l KCSWDM lsopluvial Maps Figure 4.1 -Existing Conditions Map Figure 4.2 -Developed Conditions Map KCRTS Input Parameters & Area Calculations KCRTS Rainfall Rcginns and Scale Factors Map KCRTS Duration Curve Graph 5. Conveyance System Analysis and Design 6. Special Reports and Studies 7. Other Permits 8. CSWPPP Analysis and Design 9. Bond Quantities, Facility Summaries, and Declaration of Covenant to. Operations and Maintenance Manual Note: Sections 5 -to are not prepared at the preliminary plat stage. The appropriate design information and supporting documentation will be prepared at the final engineering stage. T~!hol Highlnnrl5 DC! Oi7M 1. Project Overview TJlbot Highlands DCI 07"/i,4 I. Pro.iect Overview The proposed Talbot Highlands Pia! is a 12-lol single-family project at 16808 106'11 Avenue Southeast in Renton, Washington. located in the R-8 zone. The project area includes tax parcels 008700-0240 and 008700-0245, totaling approximately 1.93 acres. The existing site includes two singk-lilmily homes, sheds, and gravel driveways. The remainder of the site is pasture with a wooded section in the northeastern corner of the site. The overall elevation change within the site is about 15 feet, sloping down from the NF. to the SW p01tion of the site. The slope throughout the majority of the site is about 4 percent or less and ranges up to 13 percent at the NE corner of the site. The site is bordered to the north, south, and east hy single-family residences. The site is bordered to the west by 106111 Avenue Southeast. Site development will include frontage improvements consisting of shoulder widening and sidewalks along with a new public road extending into the site from 106'h Avenue Southeast. The road has been designed to provide future connectivity to the parcel to the south. Other plat improvements will include internal sidewalks, utilities, and a combined detention/wet vault. All existing structttres will be removed and 12 new single-family residences are anticipated. Talhol H1ghla11~~ DCI ll7764 KING COUNTY. WASHIN(;T();;_ .'il;RFACE WATER DESIGN MANUAL TECHNICAL INFORMATION REPORT (TIR) WORKSHEET FIGURE 1.1 Part 1 PROJECT OWNER AND PROJECT ENGINEER Project Owner R.W. Puget Sound Holdings, LLC Phone 253-835-1802 (Russ Hibbard) Address 2011 South 341st Place Federal Way, WA 98003 I Project Engineer Harold Dunc~nso~,~--- Company __ _ Duncanson Company, Inc. Phone ____ 2_0_6_-2_4_4-_4_14_1 __ ~ Part 3 TYPE OF PERMIT APPLICATION l!l Landuse Services ~bd1v1soi:)/ Short Subd. Building Services M/F / Commerical / SFR , D Clearing and Grading · D Right-of-Way Use ID Other / UPD Part 5 PLAN AND REPORT INFORMATION !---····------------------ Technical Information Report Type of Drainage Review~__,; Targeted (circle): Large Site , Date (include revision , dates): I Date of._ '-'Fi'-'n .. al"-: _______ _ Part 6 ADJUSTMENT APPROVALS Part 2 PROJECT LOCATION AND DESCRIPTION Project Name Talbot Heights Plat ------- DOES Permit# __________ _ Location Township _2_3_N ____ _ Range _5 E Section SW 114 of 29 Site Address 16808 106th Avenue Southeast Renton, WA 98055 Part 4 OTHER REVIEWS AND PERMITS D DFW HPA D Shoreline D COE 404 Management D DOE Dam Safety D Structural D Rockery/Vault! __ FEMA Floodplain D ESA Section 7 D COE Wetlands D Other Site Improvement Plan (Engr. Plans) Type (circle one): ~h / Modified Small Site Date (include revision dates): Date of Final: Type (circle one): Standard / Complex I Preapplication / Experimental/ Blanket Description: (include conditions in TIR Section 2) -------------------- I Date of Approval"-:------- 2005 Surface Water Design Manual 1/1105 l KING COUNTY. WASHJ;,,;(,TO'\. SllRFACE WATER DESIGN MANUAL TECHNICAL INFORMATION REPORT (TIR) WORKSHEET I Part 7 MONITORING REQUIREMENTS . Monitoring Required: Yes i::J:l.V I Start Date: . Completion Date: L. ----- 1 Part 8 SITE COMMUNITY AND DRAINAGE BASIN ' Community Plan : ___ N~/A _______ _ Special District Overlays: ~N~/A~_ ... __________ _ Drainage Basin: Duwamish -.GreE:on River __ _ Stormwater Requirements: Flow Cont~~I ar~d_Y','.9J~.'.. Quality Part 9 ONSITE AND ADJACENT SENSITIVE AREAS ~------=1 D River/Stream ------------___ _ D Lake D Wetlands ____ _ D Closed Depression ________ _ 0 Floodplain ···-··---._ D Other _______ _ ~art 10 SOILS Soil Type AgC Slopes 4-13% I ' D Steep Slope ________ ~--1 D Erosion Hazard __ _ 0 Landslide Hazard ____ _ D Coal Mine Hazard ______ _ D Seismic Hazard -------- 0 Habitat Protection D ______ . Erosion Potential Low --------- --·-------------------- D High Groundwater Table (within 5 leet) , D Other ____ _ 1--D Additional Sheets Attache_d __ D Sole Source Aquifer -J' D Seeps/Springs ~ ... 2005 Surface Water Design Manual 1/1/05 2 KING COUNTY, W ASHINC,TOK. S \'.RFACE WATER DESIGN MANUAL TECHNICAL INFORMATION REPORT (TIR) WORKSHEET Part 11 DRAINAGE DESIGN LIMITATIONS REFERENCE LIMITATION/ SITE CONSTRAINT [!) Core 2 -Off site Analysis D Sensitive/Critical Areas D SEPA 0 Other 0 D Additional Sheets Attached ---------------------------- -----·- I Part 12 TIR SUMMARY SHEET Threshold Discharge Area: (p_r~vide O!~~ T OL.wam1sh IR Summa~ Sheet per Thr_eshold Discharae Area\ -Green River -------· I (name or cle,_-,sc--cr ... ip-.-t"ioc.:nL) _____ __ Core Requirements (all 8 apply) Discharae at Natural Location Offsite Analysis 1 f Natural Discharge Locations: -----Number o Level: <cl' _,)2/3 dated: f---------------------Level Flow Control 1 Jq)! :i' or Exemption Number (incl. facility summary_sh"'e'-'e"t),__ __ _ Conveyance System ~rosion and Sediment Control Small Site Spill conta BMPs inment located at: ------ Supervisor: hone: s Phone: Tract A TBD ESC Site Contact P ________ __ __ After Hour Maintenance and Operation Responsib ility: Private ;iJl:~_blR:) Maintenance Loa Reau ired: Yes nTu, ______ If Private, . -- Financial Guarantees and Provided: Yes !(J'fo) Liability ·------------ Water Quality Basic")/ Sens. Lake / Type Q or Exempt Enhanced Basicm I Bog (include facility summary sheet) ionl'Jo. _ _ ----·-_ Landscap e Management Plan:Ues)/ No __ A/ SDO /MOP/ BP/ LMP / Shared Fae. ,([!_a~ Special Requirements (as _ _applicalJleJ _____ _ Area Specific Drainage Type: CD Re uirements Name· - Floodplain/Floodway Delineation Type: Ma jar / Minor / Exemption /~~ 100-year Datum: Base Flood Elevation (or range): ______ Flood Protection Facilities Source Control (comm ./industrial landuse) 2005 Surfoce Water Design Manual ---------. - Describe: anduse: Describe I LJescribe a ny structural controls: ----- 3 I /I /05 ------ l ---· -- KING COUNTY, WASII!N(.TOc;. Sl;RFACE WATER llES1GK MANUAL TECHNICAL INFORMATION REPORT (TIR) WORKSHEET Other Drainage Structures Describe: High-use Site: Yes CNo\ _, Treatment BMP: Maintenance Agreement: Yes /~ with whom?~. ---~------------- --------------- ----------=---------- [ Part 13 EROSION AND SEDIMENT CONTROL REQUIREMENTS MINIMUM ESC REQUIREMENTS DURING CONSTRUCTION [!I Clearing Limits [!I Cover Measures [!I Perimeter Protection [!I Traffic Area Stabilization l!l Sediment Retention · l!l Surface Water Control l!l Dust Control l!l Construct_ion Sequence --···- MINIMUM ESC REQUIREMENTS AFTER CONSTRUCTION [!I Stabilize Exposed Surfaces [!I Remove and Restore Temporary ESC Facilities [!I Clean and Remove All Silt and Debris Ensure Operation of Permanent Facilities . [!I Flag Limits of SAO and open space preservation areas Other Part 14 STORMWATER FACILITY DESCRIPTIONS Note: Include Facilit Summar and Sketch Flow Control I ___ Type/De~cl]ltion ---_-+-------'W=at'-"e'--r -"'Q"'u"'al"'it,__ __ +-_Iype/Descri tion l!l Detention D Infiltration 0 Regional Facility D Shared Facility i O Small Site BMPs D Other 2005 Surface \Vatcr Design Manual Vault D Biofiltration Cl Wetpool 0 Media Filtration 0 Oil Control 0 Spill Control 0 Small Site BMPs 1: ; ~ Other _J~-- 4 Wetvault 1/1/05 KJ:s;G COUNTY, WASIIINCTCJC'. Sl'RFACE WATER DESIGN MANUAL TECHNICAL INFORMATION REPORT (TIR) WORKSHEET -------------------~-------------------------~ Part 15 EASEMENTSfTRACTS D Drainage Easement I · D Access Easement D Native Growth Protection Covenant (!) Tract D Other Part 16 STRUCTURAL ANALYSIS (!) Cast in Place Vault 0 Retaining Wall · 0 Rockery > 4' High I I I g Structural on Stee-p Slope l__l:__ Other -------~=------- Part 17 SIGNATURE_9F F'ROFESSIONAL ENGINEEc..,R ________ _ I, or a civil engineer under my supervision. have visited the site. Actual site conditions as observed were incorporated into this worksheet and the attached Technical Information Report. To the best of my knowled e the · forma · provided here is accurate. if/dee Signed/Date 2005 Surface Water Design Manual I /I /05 5 S 21st St S J/t1·, S' ,,g,-!;, ·-~-· :; g • ,,. ~ l:' ~ <C • ~ I Aves Se Carr Rel , J • a . "' !C ~ • 5,e 161.)th St "' • ~ ~ • > ! <( ~ = -- s-~ :66th St Se 119th Pl • ~ l: <( £ ~ ~ w " la" • ~ " Se 160th Pl ~ " ,,. ~ If Sc 164th St 5-c! 165th St J: • ~ ! -5€ 168111 St ~ 169th St i " If 1 Se 171st Ln o,~' ,, Se 112nd St Se 112nd Ln se 17 1rd St ,,~ ~ • * ~ , • .0 • '% .,,. ' ~ (~ !'! '\:. S<'.' 1/~th St - • :::: Se 176th St ~ f g <( :a Sf 5 !C "' ~ -!C Benson HIii () 2DD m 6DD ft DUNCANSON CO_MPANY, INC. Ci1·il Engmccnng · Surveytng · Lan::! Planning i-15 SW 155th St, Sum 102 Seattle, Wa~hmglmJ 98166 l'hmie 2(16.2./4.4141 Fax 206.244.-1-155 Figure 1.2 -Vicinity Map Site@ 16808 & 16816 106'' Ave SE Renton, WA 98055 Scale: As specified Drawn: KCF Job No: 07764 m ~ ~ $2 ---30·--- I i ,,.,. I ~ ' ~.~ """"'7'o~·, .. ?09_8 _,. I i~ l ' 8 I l - I ··1 I ·.· .. I {1 , , ,, ~. : ~r~ c~ ~.-1 9 I 'j ~ ~ .,._ ._ J o r _ I Dz ~ I • a j j-------..c_ ____ __J : A_ 1 3 1--'---.f _'.' 6 , . I. - I ~! :_r -1 : I ,_ •• : f ~ ~ .. )':: ::-'~ 10 N "rt... I .. • ... • . ----;-co .. ,,• " .... -.,.~... . . . ~·. ..._ : ·\ • 0 .. ' .'; SE 168TH PL ~ : a --z . /..I . ··· ~,. W F--I'..._ f( / . . ,· . . . .. D~ ii -'.-~1 n . 'i '\ ~-iE .... J . ~ -, I ~ $2 i------_J ' -1 - 16 '-.• J 1-=-_!.-, ..,---DRIVEWAY ENTRANCE, l"YP _ 1:. 30 . ~4--TRACT A ? /: , ~I 1/ wsoor PLAN r-ao.10-00 . ~-·i ~w . e-' _ 12 ."./ e •• ~ ~ - : / Nes·1 s 52' w 299.,., • X: \OPROJECTS\07764 TALBOTHEICHTSPLA T\07764LDT\07764M0Dc.DWG ~ ~ BASIN BOUNDARY, (2.08 AC"'cS) TYP. L ~ I ' GRAPHIC SCALE 0 ED 20 40 80 (IN FEET) I inch ~ 40 ft . DUNCANSON COMPA.NY INC Civil Engineering Sur,:eymg -I.and Planning 145 SW 155th Street, S11ite 102 Seallle, Washington 98166 Phone 206.244 . ./ Ni Fax 206.24I.f..155 Figure 1.3 -Drainage Basin Map Scale: I" ~ 40' Drawn: KCF Job No. 07764 AgC = Aldcrwood G ravel ly Sandy Loam, 6-15 % s lopes. OUN CANSO N CO M PANY, IN C. r1\1 I Engmccnng · Survqi1J8 · L.1ncl Pl anmnJ:t 145 SW 155th St, S1111e /02 Seaule. Wa,h111gto11 <Jli/66 /'ht.me 206.1./4.4 141 rax 206.244.4455 Fig ure 1.4 -SCS So il S u rvey Map Site @ 16808 & 16816 I 061 " Ave SE Renton, WA 98055 Scale: As specified Drawn: KCI' Job No: 07764 Talbot Highlanri<; 2. Preliminary Conditions and Requirements Summary ,1/2/0~ D('I 07764 2. Preliminary Conditions and Requirements Summary The City of Renton requires compliance with the 1990 King County Surface Water Design Manual (KCSWDM). This section describes how the project will meet the Manual's Core and Special Requirements. King County Surface Water Design Manual Core Requirements: I. Discharge at the Natural Location The existing site runoff sheet !lows generally southwest into the ditch along 1061h Avenue Southeast. Developed !lows will maintain this natural drainage location. 2. Offsite Ana\vsis A Level 1 offsite analysis has hccn performed for this project. See Section 3 for more information. 3. RunoffControl Runoff control will he provided through the use of a combined detention/wet vault and shall be designed per the 1990 KCSWDM, as adopted by the City of Renton. Site soils are not suitable for infiltration. See Section 4 for further analysis. 4. Conveyance System Site !lows are relatively small compared to the nominal capacity of 12-inch minimum pipe size. Appropriate conveyance calculations will be included in Section 5 at the final engineering stage. 5. Erosion and Sediment Contr_o_l Implementation of 1990 KCS WD\11 TESC measures will be used onsitc during construction activities. A Tf,SC plan will he included at the final engineering stage. r~lbut ll,ghland1 DCJ 07764 King County Surface Water Design Manual Special Requirements: I. Other Adopted Area-Specilic Rcc1uircments This requirement does not apply. 2. Flood Hazard Area Delineation This site does not lie within the I 00-year Hood plain. 3. Flood Protection Facilit_L<;_s This requirement does not apply. 4. Source Control This requirement does not apply. 5. Oil Control This requirement docs not apply. Talhm Hi~hlnnds DC'I 07764 3. Offsite Analysis Talbnl H,~1,larirls 4/~/08 DG/J77M 3. Offsite Analysis Task I • Study Area Definition & Maps The study area was determined by lick! observation and a review of the City's aerial topography maps. The study area consists of the downstream flow path generally extending south for a distance or 1;,-rnilc from the site. See Figure 3.1 Offsite Analysis Map. Task 2 · Resource Review 1. Adopted Basin Plan Not applicable 2. Finalized Drainage Studies Not applicable 3. Basin Reconnaissance Su111111m-v Reports This project is in the Duwarnish · <ircen River Basin. 4. Critical Drainage Area Ma11s Not applicable. 5. FEMA Maps Not applicable. 6. Other offsite analyses Not applicable. 7. Sensitive Areas Folio The King County Critical Areas iMap shows the site as a low condition. See Figure 3.2. Talhul H,.i:h1"11d, lJCJ 077M 8. l)rainaf;e Complaints and S111dics Drainage complaint summaries were obtained from King County. The drainage complaint parcels arc shaded ornngc and have been assigned a drainage complaint number (DC2 for example). Sec Figure 3.1 -Offsite Analysis Map. Three drainage complaints were found to be in the downstream flowpath. Below is a description of how each drainage complaint has been addressed. DC I: 1988-0511 This drainage complaint is more than 10 years old, therefore it is not applicable. DC2: 1984-0084 This drainage complaint is more than IO years old, therefore it is not applicable. DC3: 1990-1553 This drainage complaint is more than IO years old, therefore it is not applicable. 9. USDA Soil Survey See Figure 1.4. Soils noted as A!,'.C ~Alderwood Gravelly Sandy Loam. Till Soils. No problems were identified. I 0. Wetland Inventory Not applicable. 11. Migrating River Studies Not applicable. T~lho1 llighl~nd; 4l2/ll8 DC! 077M Task 3 -Field Reconnaissance A Level 1 field reconnaissance was conducted on September 17. 2007. Weather conditions were overcast and rainy. The downstream flow path was observed for '/4 mile. A discussion of the various clownst ream runoff system components is contained under Task 4 below. Task 4 -Drainage System Description And Problem Screening Component A -Ditch and I 2" Cull'ert Svstem (0' -1,025 ') Runoff exits the site at the southwest comer and flows south along the western ditch of 106'11 Avenue Southeast for appro~irnatcly 1,025 feet. The ditch has an 18-inch average depth and contains vegetation. The ditch system includes 12-inch culverts at the driveway entrances. No problems were observed. Component B -12" Pipe System (1,025' -1,150') Ditch runoff is collected by a catch basin located at the intersection of 106'11 Avenue Southeast and Southeast 172"'1 St reel. The upstream catch basin at the intersection was heavily covered with vegetation and debris, which could create a standing water problem during heavy stom1 events. From the catch basin, the runoff flows in the southwestern direction through a 18-inch ductile iron pipe for approximately 125 feet. The pipe appears to discharge into a heavily vegetated and vacant parcel, #2923059148. No other problems were observed. Component C-Sheet Flow (1,150' -l,300') The runoff appears to disperse throuµh the heavy vegetation on the vacant parcel and flow southwest to the public drainage system along Benson Drive South. There were no signs of a concentrated flow path or standing water on this parcel. No problems were observed. Component D-12" Public Drainage Svstem (1,300' -1,320'+) The sheet flow runoff appears to llnw into with the public drainage system along Benson Drive South. The public drainage system consists of 12-inch pipe and catch basins that direct the runoff in the northwestern direction. No problems were observed. This component carries the runoff over 1/4-mile downstream from the site. Task 5 -Conclusion It is recommended that the debris be removed and that the vegetation be cut hack to prevent clogging from the catch basin in Component B. It is Duncanson Company's opinion from the available information that the developed site will not create or aggravate any downstream conditions. on 07764 OFF-SITE ANALYSIS DRAINAGE SYSTEM TABLE SURFACE WATER DESIGN MANUAL, CORE REQUIREMENT #2 Basin: Duwamish-Green River Subbasin Name: Subbasin l'lumber: - Symbol I Drainage Component Drainage Slope Type, Name, and Size Component Descrieticm See map. I Type: sheet flow, swale, stream, Drainage basin, I % channel, pipe, pond vegetation, cover, Size: diameter, surface area. depth, type of sensitive area, volume. A ! Ditch & 12'' Culvert System I =3~1o ·---------,, B 12" Pipe Svs1em ± ..,Q/ _) /0 ! ' C Sheet Flow ±5% - D 12" Public Drainage System ct5% ~-~·-- . - ' I I I I ·-- I ,: - Distance from site discharge I ~ml= 1,320ft. O' -1.025' 1.025' -L 150' I 1,150' -1,300' 1,300' -1,320'+ i ' ' ' ! - Existing Problems Potential Problems Constrictions, under capacity, ponding, overtopping, flooding, habitat or organism destruction, scouring, bank sloughing, sedimentation, incision~ other erosion. l\onc l None None Standing I ,vatcr None None None None ·- i ' I - ' Observations of field inspector, resource reviewer, or res_i_de~1 Tributary area, !ikel1hood of problem, overflow pathways, potential impacts. [;pslrcam catch basin has oYergro\Yn vegetation and ji debris. Crosses under SE 172nd St. ! -~ I -~I ! I I ~ I D UN C AN S ON CO M PA NY. I N C ('1\11 t:ngn ... ~.:-nng · ~tlf"\~\ln)! • Land l~:11111111)! I 45 Sir I 55J/, .\1. S111 1,· JO: Si.,allll•. IJ l.1,lm~r,m 9~/t,6 Jt/JJ,m• !IM.~-1.J . ./J II rt/'I: :.06.:./-1.-1-135 Figure 3.1 -Offsite Analysis Map S ite @ 16808 & 168 16 l 06'h Ave SE Re nton, WA 98055 Scale: As s pec ified Dmwn: KCF Job No: 0 7764 Legend 00dl!J!Y.J1/0 ~ Highlighte d Feature -1 I_ County Boundary X Mountain Pea ks CAO Shore line Condition 00810001 ff ~ l h gh ~ t.1od ,um Low OOE:1/0001/6 Highways /V Incorpora te d Area Streets tt ,gn·"'"l' u~BIU~!.1 181 A n crr'3~ l.o<.11 Parce l s Lake s a nd Large Rive rs Strea m s CAO Sasin Condition O!JBIU00186 D 11 ,gh rcontl D Mocuum D l ow Shaded Re lief w .., w < ~l!JBIOOOJJ: O'J8/!JO'J2J! !J!Jlj/!)()(lJJj OO~IO!!OJ2/ R 008/!JOO'-'.f~ 008/00DJU 008l!JOO.l~J D0tfl!>r>DJ1ti U!JBIOO!JJ I I !JOBIOOOZ!J!, DUNCANSON CO M PA N Y I NC ( 1\II i ni::uk.·..:nnJ! 'm"' .... "-Ull-: L m .t PJ.11111111~ 115 .\II 1551/, .\/, .\mh· 111: .\t·allk. Uu,Jnngtm, Y\/66 J>1>0111 • }06. ! .J .J -I /.JI I (I\" :or,: I I /.155 Figure 3.2 -Critical Areas Map S ite @ 16 808 & 16816 I 06'h Ave SE Renton, WA 98055 Scal e: A s spec ified Drawn: KCF Job No: 07764 4. Runoff Control and Water Quality Facility Analysis and Design DCI ri;-;r.,1 4. Runoff Control and Waler Quality Facility Analysis and Design Part A -Existing Site llvdrnlog, The existing site consists of inclt1cks c1 two single-family homes. sheds. and gravel drivcwaYs. The remainder of the .silc is p,rsture with several clusters of trees. See Figure 1.3 -Basin \.1ap The site includes ctppruximatcly 1.93 acres. The overall site basin is approximately 2.09 acres. which inclu,k frontage improvements consisting of shoulder widening and sidewalks. See lig11rc I 3-\lasin Map. The site basin naturally drains to the s0uthwcst portion of the site. The c.,isting sile hasin conditions are shown hclmv: EXISTING SITE BASIN BASIN AREA TOTAL IMPERVIOUS 1 OU/AC Total TOTAL PERVIOUS Total 90.953s; 12,643sf 12,643 sf 78.310sf Design Storm 24-Hour Precipitation Values 2-ycar design storm event 5-vcar design storm evem l 0-ycar design stonn event 25-year design storm event l 00-ycar design storm event 'alr,nt I ltrdil,ar,IJ, :.o inches 2.4 inches 2.'! inches ~ .4 inches ~.q inches 2.088acres 0.290acres 15% of site (KCSWOM Table 3.5 26) O 290acres 1.798acres D\J 0~ 164 F J \ r_; C' r·i l \ l' Y. \V /\ .\ !-! I ~ IZ ,\ C E W ,\ T I. I, I l I -' I r; "i \1 ;\ :\ l -\ L ·r c111u; .1.5.2B S( \ W!SITI!'\ \\"A.Sil]'.(; Ir,, lff,(JFF nmvE NUMlll:RS i ,--------- F,unof: cur•.ic n11rn:JE' r2.1dal'. distri!Jut1on ~:.: · ·::\·I <-JC_jricu:tural, suburt)a~1 and urba:-·, 12.nd use ir_1r -ype 1,; q:1':~1 dumt1on LAf-JG JSE DESCr.lPT!ON ~ ------------------- ! f,1c,ur-t21n n:wn cirr:r1s: MeacJ-::iw or Dasture -------- \\'uod -::r ;ores: lnnd· \NocK:1 er 7:Jr,:s: lam:· J~:1·1ard winter · ·:r1,::t1-.,·· low gr, 1·1,1· :· ~,, '"·", 2110 grasslancis und1s:. \'0'-n,'.; w·1th C, , _;-:-~ SE'CCllld g:ov,r:h e.·,,,_,-:h CH Dr __:sh r::URI:: ,f,,JMBc:::is BY HY:::-;F:GLQ,'..;IC SOIL GRCUP .A B C D &3 g1 94 95 /l1 62 89 92 c;s 7B 85 B9 ·12 G·l 76 81 ~-5 81 85 Bi ll8 92 q4 I I i ! ----i i ----1 I -------, '.Jc.ier-1 spaces. iawns, pa;r-:s, golf cc:urse~ ----------- iancsc:::;::ii'lg goos conJ'·tiDn '.Jrasc; 1-_ ._.. or ~c·~, 1:,;3 fair condition: Gr2ve1 :c:2ds anc pc,,.;:1rg 1ots o:rt roads a:-ij ;:ian<in,g lets gross -: to 75° lr10>:r.1ious su:iaces. ;}fh'eT1ert. :,::,ts. e:· Ow~n ·\'\'ater bodies ia.Kes ·!,-= .. ;-1'· :-i,--1:1ds, etc. ---,---------------- SinglP =arn1I\• Reside·1:ia ,:21 Dv1el1ing Uni:/Gross Acre 1r:::·:Z:'·1ous {3) 1.0 8U/C~A -----------~LL~ 1 5 JL . .1 iGA. 2 0 :JJ GP.. 2.5 JU, GP.. D~ GA 2-f:· :JU,..(3F. 4 C DU. (:...P.. 4 5 DU ;'Gfa. 5_c:, DU /GA 5.5 DU/CJ.A fi_r, CU /C~A 6.5 DU,SA 7.0 DU/GA j ;:il;rnnerl :Jnit devel:::.iµrner'.\s I condorniri1.Jms. apart:11e:1:s :ommrrr.ial ~-usin2ss am~ -1n·'"'1 '<:1"1·a' arP::,S [_ ,c,. , LI -LI . ::1:: ,(~fVIOUS ,.,. :·e computf'd i 5il 80 86 gc, -7 85 §1 92 75 BS 29 91 -82 87 89 98 98 Lill 98 1 :JC ~ OD 100 1DO Seoarate c 1.Jrve nc.Jmbe· sl1all be selected fur perviCJL'S and rn:iervious portion of the site or basir' ___ ., ___________________ _ '.1! i=w 3 more cet2.ilec description :Ji ,_1._; ·r .. _.lt ::,1 ;;-mcJ use cu:ve !;l,mbers reie~ to ~lationai Er1,Jineering ~anclbook. Sec:t1on 1.. ·r1ydrolocyy-'. ::=.· ::;,i,0 ; :) ;:.,_Jq'JS! 197? fa.ss:..:rnes roof anc drivev,,ay rtmot' i .. ,to street 's!or:11 syster:-, ~1e re·~a1·11r g per.1 m.s mPcJS (,a,' ;·;i,·ered :o !w 1~ ·JCJUJ cunJit1ur·. ill' ~h;sc c·Jr,1 e nurn'ners ------------------ L I ·\ ,: ,' l. ( 1 '. h '7 : \\ , 11 1 \; c, ------ FJ(;l'Jm 3.5.lC 2-YLAH ,4-ilOl'l, L,OPU \ i ,.; , --~-~--·'·-~ '·1 -"---~ '-1 ,,.,_. ' ,>;-, -· I I " ~ i ~· fl) rv rv ~ r:v 2-YEAR 24-HOUR ·:ipE-r'1PITnT•('',t I_ t .i='~·•i, ,/-',.f-./1~ 3.4-ISOPLUVIALS or: 2·'fff,.R 24-HC,':' TOTAL PRECiPli/JICJrJ IN INi .. :hf \ 0 1 2 3 4 '.. I l · 300,11(,U \ \ I ' .. 4: ...• 1\. \· \ )\ ' ) I (' ~ -·-_-ij:.'t -J._ 18 --__ -__ :_ ,: ____ -'/:, __ , 1 .: 1 ~ I ':· -_. •- 9 --_,!_ ' -· -/ 0 '. .• / \ -;1----'---_-·""'"' '"' 2~1 ·1, <7 -' ,'. --/ , ., ... I 22 --· 1 i __ ,, • 2 , ·_: !''\ ... ~"" :, ,r~l!lll1 IW!Jr\~ .,3 I_ ·• I } •••• _..,..., '...,,,....) . .,.,. ::~: . ,.,....,,•"'': ' / -- -~. --~ _, ... -._ . ~---'--' ., --~ -, ! '· 5-YEAR 24-HOUR PRECIPIT.A.T!Oh 1,3.4- 1 1SOPLUViAL$ OF S·YE,1~11 '2fl-1ii";I_JP TOTAL PRECIPiT/\TlON !N iHC:;E - ~..--:.'.-r--~ 1: .100,:wn _, ~·· ) --• -...., -'1,.- 1 /lJ() . c· (\ I ~ -, f ~ I /-... C J , y. \\ .\ : . !i I ~ I i \. --R,..._,,,-1orrt-1TlO __ t,,/ I-AYEAR24-HOUR p :,t;:~: ;; ;L,HUU_" .... Al s OF l<hL.,, ·--·1•,.·. J.4-RECIPI 'b. · 1'· ''. IS OPLUVI -' · .• -_T''JP 11-; II·.>•,.-1 •. · TOTAL P' (, i ::, [· f ·. j 1,1~ ,1 -~---:-----~.:..:-.---c:c~---=--- 'MAl,_L'AL I. R r, __ E_,l <, ~ --\\ ,~ 1 : l l~ l i\ ( I.: . - ( I . -I ; '-. ,, 11 I ' . ' ,::·~ / . ·r I / ' ·;· ., ' I / / ,-, 1 •-j :-.1if,c 3----~-~--- ; I !~ ) \ ! . I \'-.\. I T i-I< Ii !· \ 1 (I N ~1 ' N I, A I '-.__,-' 4 .5 1 /0() ]! i: j -: i l: ·1 1-;, , r 1 V.' \ , - -,.---... -~ / . '-._ ·---~ -) \ cc O') . 0 / .. •· ... '11<)11 /~ . ,,. Part B Developed Site Hvdrolog, ['he developed site shall consist,,, I: nc\\ single-family residences and a new public road extending from 1061 h Avenue SI .. J'h,· dl'\elored site basin conditions are shown below: DEVELOPED SITE BASIN BASIN AREA TOTAL IMPERVIOUS Lots (>5,000 sf) Lots ( <5 000 sf) Tract P., Frontage Improvements Road & Sidewalks Total TOTAL PERVIOUS Total 90.953sf 10,000sf 18,72Dsf 1.000sf 4,280sf 16,238sf 5D,238sf 40.715sf ~-'2/0H 2.088acres 0.23Dacres 0.430acres O.D23acres 0.098acres 0. 373 acres 1 153 acres 0.935acres 2,500 sf each 50% of lot area 42' total width Part C: -Performance Standarcls The City of Renton drainage dc:.s1µ11 sta11d,1rds specify that the peaks from the existing and developed conditions shall be c:ilc11l,ncd using the Santa Barbara Urban l lydrograph to determine ii.the drainage threslrnld c·.,crnntion (0.5 cr·,1 is excccclcd. See figure 4.1 and Figure 4.2 for existing and devclop,·d l10,q1aths used to detcnninc the respective peaks. As shown in the tables below and the t,·,llnwing page. the developed peak l OU-year runoff does exceed the existing by more th:111 1\.5 cfs. Therefore, the KCRTS Level 2 flow Control (1998 KCSWDi\·1) stancicml "ill be used for detention sizing. f:xist !{vent Summary Even I Peak Q ( cf s) 2 year 0 2775 5 year 0.3874 10 year 0.5317 :::'.5 year 0.6806 100 1·ear 0.8323 Design Method Hyd IntY Peak T (hr,1 8.17 8.17 8.17 8.17 8.17 1 h cl \ r,I (acft) Area (ac) Method Ir 18,7 2 0880 SBUl-1 ('1_24 -.;4 2 0880 SRUH n.?.: 10 :'.0880 SRUH (1_ .. 1-1)()7 '.'.0880 SBUJl 11..IS 19 2.0880 SBUH sn1. 11t Rainfall type ! ().()(1 min Peaking Factor Abstraction Coeff Pervious Area (AMC 2) PerYious CN !..f\lJ rlC sq .. ;~ DCIA DCC:'< Pen'ious TC ~(I 1.='. min DCTC l'l'nious CN Cale Dcsrript ion Open spaces, lawns. p<1r\..;~ f'i(l-~'~% grass) Impervious surfaces {p<:\C'!llL'11'.',. roofs. etc·) Perviouc: ( 'nmp,1c,11<..:d CN (AMC 2) Ptn ious TC C:-tlc SubArea 180 ac 0.29 ac Raintype TYPE IA TYPE IA TYPE IA TYPEIA TYl'F:IA TYPE IA 484.00 0.20 0.00 ac 0.00 0.00 min Sub en 90.00 98.00 91.20 Type DC'scripl ion Length ' Slope Coeff Misc TT Sheet '0/oods or forest with light und::rkmh. 0.40 '300.00 ft 4 00% 0.4000 '.2.00 in :119.57 min Shallow .Shon grass, pa~turc and )3\'.-11>-(11 --r1_r:_;rn 50.00 f1 2.00% 0.0300 !0.5:'i min ,50.12 min lalh": li,~h:n"" Developed Event Summary Event Peak Q (cf.1) Peal. T (hr, I I In! \ ol (acft) Arca (ac) 2 year 5 year !(I yea, .25 year lllllyear 1.2519 1.9023 2.2606 2.6172 Design !\1cthod Hyd lntv 8.011 8. (1(1 8. 011 8.00 S.011 /1 .'._.::IO J.:?A 10 <.0410 (1 (/)()(i :,.2410 3.24!0 3.2410 Sill II I Rainfall type I /J (l/1 min ·Peaking Factor Method SBUH SBLH SH\ I!-! SHIii! SRllH A hstrnction Coe ff Penious Arca (AMC 2) Penions Cl\' '(jC; <1( ;DCIA '>(, 41! DC CN Pervious TC I' ur: 1:1in DC TC PtrYinus CN Cak Description Open spaces. lawns, p:ut.s: (.:;r:, -c51:o grass) Impervious surfaces (p;1\rn;_,11h. 1uofs, etc) Perviou~ 1_ :1111p1·i-.1il'1.: CN (AMC 2) Pen ir,us TC Cak SubArea 0.94 ac 1.15 ac Raintypc TYPE IA TYPE IA TYPE I,\ TYl'E I A TYl'EIA IYPl:lA 484.00 ll.20 1.15 ac 98 00 1.19 min , I I Suh en 90.00 i ')8.00 94.42 1: ,. Type Description Length 11500ft 170.00 ft 80.0(1 ft Slope Coeff 1\1isc TT !i Sheet Short prairie gras~ :ml! Lrn·1b . 0.15 Channel ( intern,) CMP pipe (n~0.02-l I Channel (cont) CO"ITINO\JS Fl 0\\ -F 0 ,(I -i Type DirL·rtl: Connected CN Cale Dcscriptir,n Impervious surfaces ( p:1 \'Clll·~·11::,. 1 ~)ofs, etc) DC C,11qw.c;i1,:d C'< (AMC l) l>irectl: ( rn111ected TC Cale Dcscri1>tic1n Length Channel (intcrm) !CMP pipe (n=0.11::'.,+ ·1 170.00 f1 Channel (cont) CONTINOUS Fl .1 >II -F (;.4 80.00 ft U1 rl·~·t I~ ( ·11nm:cted TC 3.00°/o 2.00% 14.00% Slope l.00°/0 i,1.00(~0 ·0.1500 2.00 in 11.78 min 0.0240 0.94 min 0.0300 0.25 min : 12.98 mini SubArea Sub en 1.15 ac 98.00 98.00 Coeff Misc TT ,. ,, " 0.0240 0.94 min 1: ,, ,, ' '0.0300 0.25 min 1.19min DCI r;",71,.1 w ff) w ::::J z ~ <I'. I f-- <D 0 ~~o··-l-30·-- 2 iii N w "' 0 '" • 0 • I R2"'~ ---=@2.0% X, \O?PROJEC"S\07764 T ALB OTHC:IGWSPLA ·\o 7764LDT\0776 4MODL. DWG N_!38"17'0_J:w .£99.RJ' '" ~ w b 0 "' • 0 z \!88"16°S2"W 299.8.3' <{ ,, c:u: ,.__..· ~ GRAPH lC SCALE 40 A_~. Iv "'~ 20 40 80 (IN FEET) I inch=---40 ft. JUNCANSON COMP.A.NY. INC Civil Engineering ::Surveying LJnLI l'la11111ng 145 SW 155th Street. Suite 102 Seattle, Washington Y8 l o6 Phone 206.244 . .//4-1 Fax 206.;}4-4 . ./4-55 Figure 4. I -Existing Site Conditions Scale: I" ~ 40' Drawn: KCF Joh No. 07764 I I /v I i I I I r--~ I I 4 1'.Be·, J'c:rw 2s9 s.;· I \ ~ ~2~ " " "-----~'ill>-" I -, I ~- ~ ->, I ;" I w I I I -I -~, I "', en / I I 5 I : w I 2 I \ I ~I Is I i~ > -~-I <J.'.: I ~ ' w I 8 --------to 2--l 0 ~ /I\ , l.1,.,, 6 \ I I "--- i I ' ~ "'- 9 10 J J I I l \ ! ' ~ ~ w .. -,L: -L.I-. ---,__~ $' "' \7 ' ----g ;., ~ 0 z L_ - [-rn'- ~-:io· ---/---30'--- I \ .l~ --------;r i TRACT A .\ X: \07PROJECTS\0776~ TALBO~HEI GHTSPLA T\07764LD"\07764PP3.DWG ~---~hY -V-·- ' r I 1 -- r LL 7 N88'16'52"W 2S9 SJ' SITE BENCHMARK REBAR :!c CAP ·oc1 CONTROL" ELEV.= 417.JS' ~~ I I I I I \ \ 11 12 \ GRAPHIC SCALE 0 Im~ I I ~# 20 40 80 ~-------------, (lN FEET) l inch----' 40 ft. D u N CA N SO N C O M PAN Y, I N C Civil Engineering Surveying · Land Planmr.g J./5 SW 155th Street, Suite 102 Seattle, Washington 98166 Phone 206.244.4J.IJ Fax 206 :!44.)455 Figure 4.2 -Developed Site Conditions Scale: 1" ~ 40' Drawn: KCF Job No. 07764 Part D Flow Control System KCRTS Level 2 Flow Control (1998 KCSWDM) standard will he provided through the use of a combined detention/wet vault located in Tract A. See the KCRTS Data Entry and Computation Sheet for detailed calculation of input parameters. Flowratcs from the existing and developed conditions arc shown below: Flow ~·requency Analysis ~imc Series Flle:ex~st.tsf Project Locati.or1:Sea-T~c ---AnffJal Peak Flow l-Zates--- Flow Rate Rank Time of (CFS) 0.148 2 2/09/01 0.067 7 ]/05/02 0. 136 3 ) /28 /03 0.039 8 R/26/04 C.080 6 1/05/05 0.131 4 1/18/06 0 .119 5 11/24/06 !i.728 1 1/09/08 Compu1:ed Peaks r;cw F~equency Analysis Tirr,e Series File:dev.tsf Project Loc~tion:Sea-Tac Peil< 1 :_,: 1;n lG:Cn 3: nc: 2: (_'1,:1 8: (J I H:' i1 : C1 :·: 6 : n r: ---Annual Peak Flow Rut.cs---- Flow Rate Rank Time o• Fe,-;'-<: (CFS) 0.363 €i 2/09/01 ::? : ' 0. 28 9 8 l/05/CP 1 f, : ll.438 3 2/?l/03 7;()() 0.305 7 8/26/04 2: 1·1 :1 C. Jf,9 5 10/2f]/04 ] (:. : :\ r) 0.385 4 J/lR/06 1c:n:: 0.443 /, 10/26/06 C : iJ r: 0.742 1 1/09/08 6: :_J(' Computed ?eaks T~lhot Tfighlards -----Flow Fr0,cp1e:nc:y Analysis------- -Pea ks ?..ank Rel urn Prob (C~:i) !_Jeriod 0.228 1 ~00.00 0 . 9 9 Cl 0.148 2 2~-1.00 0. 960 0 .136 J 10.00 0.900 0. l. 31 4 :) • ::JO 0. P.00 0 .119 ~l .1. 00 0.667 O.OllO 6 2.CO 0.500 [J.l!6/ 7 :.JO 0.231 0.039 8 1. "0 D.091 0.201 .50.00 0.9RO -----Flow t'requency Analy:;:is------- --?caks Rack Return Prob I , !,~ (D'S) Per', orl 0.71,2 1 100.00 lJ.443 2 2S.JO 0.438 3 10.00 0.385 4 S.00 0.%9 5 3.00 0. 363 0.305 0.289 0. 64? 6 I 8 2.CO '1. JO 1. 10 50.00 0.990 8.960 C.900 0.800 0.667 O.cOO 0.,.11 0.091 0.980 D(l 07764 KCRTS Data Entry & Computation Sheet Project: 07764-Talbot Heights Plat page 1 of 1 Comp by: KCF Date: 3/16/2008 Basin Name: SITE File Name: EXIST Region: Seatac Scale Factor: 1.00 Time Step: Houri Record Length: Reduced Total Acreage: 2.088 Pervious Land Types Land Use KCRTS Soil Group Cover Group Area (sf} Acreage Till Forest 78,310 1.798 Till Pasture 0 0.000 Till Grass 0 0.000 Outwash Forest 0 0 000 Outwash Pasture 0 0 000 Outwash Grass 0 0.000 Wetland --0 0.000 Impervious Land Types Land Use Acreage EIF EIA Non Effective Area Reverts to: 1 DU/AC 0.290 0.50 0.145 0.145 TG Adjusted Land Use Areas Based on EIF Calculations KCRTS Soil Group Cover Group Added Acreaqe Computed Acreaoe for Model Till Forest 0 000 1.798 Till Pasture 0 000 0000 Till Grass 0.145 0.145 Outwash Forest 0 000 0 000 Outwash Pasture 0 000 0 000 Outwash Grass 0 000 0 000 Wetland ----0 000 Effective Impervious --0.145 Total Area Check 2.088 Flow Path Data Land Use Length Slope Notes: KCRTS Data Entry & Computation Sheet Project: 07764-Talbot Heights Plat page 1 of 1 Comp by: KCF Date: 3/16/2008 Basin Name: SITE File Name: DEV Region: Seatac Scale Factor: 1.00 Time Step: Houri Record Length: Reduced Total Acreage: 2.088 Pervious Land Types Land Use KCRTS Soil Group Cover Group Area (sf) Acreaqe Till Forest 0 0.000 Till Pasture 0 0.000 Till Grass 40,715 0.935 Outwash Forest 0 0 000 Outwash Pasture 0 0.000 Outwash Grass 0 0.000 Wetland --0 0.000 Impervious Land Types Land Use Acreaqe EIF EIA Non Effective Area Reverts to: Lot Coverage 0.660 1.00 0.660 0.000 Road & CGS 0.471 1.00 0471 0.000 Tract A 0.023 1.00 0.023 0 000 Adjusted Land Use Areas Based on Elf Calculations KCRTS Soil Grouo Cover Group Added Acreaae Comouted Acreage for Model Till Forest 0.000 0 000 Till Pasture 0 000 0.000 Till Grass 0 000 0.935 Outwash Forest 0 000 0 000 Outwash Pasture 0 000 0.000 Outwash Grass 0.000 0.000 Wetland ----0.000 Effective I moervious ----1.153 Total Area Check 2 088 Flow Path Data Land Use Length Slope Notes: -- SECTION Ill FIGURE 111-2. RAINFALL REGIONS AND SCALE FACTORS ST 1.1 ST 1.1 ST 1.0 Rainfall Regions and Regional Scale Factors Incorporated Area -._.c::::::) River/Lake Major Road III-4 ST 1.0/ LA 0.8 ST 1.0/ LA 0.8 . <l LA 0.9 ' . """'"~~· • 1-- LA 1.0 LA 0.9 LA 1.0 Tlcrr1:1bu l:J, 1~395 LA 1.2 () Preliminary analysis shows that a detention vault, 60-feet wide hy 69-fect long with 5-feet of depth, was found to achieve the desired performance. Some low impact 13MP's with supporting documentation may be used at the final engineering stage to reduce the detention facility volume. /\ KCRTS preliminary vault sizing calculation has been shown below: RetPntion/Delention Facility Tvpe of F'ar:ility: [1::1 r·1 · i~'l: \/aulL Fac:i Ii t.y Length: h'·;. C1(1 f~ F'c1.cility Vhdlh: U'.. r:-'.: tt l:'acil:..Ly Area: /Ji:r:-. sq. fl Effectjve Storage Depth: ft Stage O Elevation: 1 no.('!' :.'=t Slorage Volume: cu. ft Rise:r Head: Ris0.r Diameter: '!. ,· ft J).('.11·1 inches Number of ori~ices: :;-1111 Ee:::1d Pipe Ori f i c:i:: ft Height l ;. i ,--D'' ·. c, • Discharge Diameter l 2 (ft) fl) 0.00 O.'"i1J 3.15 l.':C! Top Nolch WPir: Nc-:J• o·.Jt::£10'...., Ra:in'] Curve: Noi'c•' (C:;.'S) (i_n) o.u..:ig 0.066 4.0 Staqe F'.1(;va~ion ::1 (; l "lll" Discharge If t I I ft I ;cu. t (c1c-tt.) {cfs) (_). co 100.00 ,, 0.000 0.000 ,, . 0.01 100.01 ·11 0.001 0.002 0.02 100.02 " l 0.002 C.003 0.03 lOC.03 ] . ' C.C03 0.004 C.04 ]00.04 1 r,;;, _ 0.001 0.004 0.05 100.05 /(:·) O.OOS 0.005 0. 8 6 100.06 ? ,1 ;:, • 0.006 0.005 0. C7 JOI). 07 / '.)'"J 0.007 0.006 0. 113 100.18 ? fJ ~. 0.017 0.009 0. 2 8 100.7.8 1 _·, r) (;, • 0.027 0. OJ? 0.38 lOC. 38 ~ I")"/ _;I • C.C36 C. 013 c.~8 100.48 (] f"l "7 • 0.046 0. 015 0.58 100.58 )i1 I) 0.055 0. 011 0. 68 ~00.68 'r: -' '. 0.065 IJ.0'18 0.78 JOO. 78 ~))C. 0.014 0.019 0.88 lJ0.88 -,,;\11 ! • 0. :12 4 0.021 :J. 98 J.00. 91_1 !. ,''i '-, ! 0.093 o. on l. 08 101. :JR /..1 0. 103 0.071 1. l 8 1 C: 1 .18 t; H Ii '. 0. l J? 0.024 J .78 101. ]2 IJ/')'I. l!. 122 0. 02.5 :.38 : l! J . 38 I)/. 0 . 131 O.C26 i. 4 8 101.48 (. ! > 0. J 41 0. 027 ] -~-; 8 101. 58 (, ,,11 0. 150 0. l!JR 1. 68 181. 68 (-, q I) I. 0. 160 0.028 1.78 1 01 .78 I -;( '-1. 0 . 1 69 0.029 1.88 101.88 I i H ·; _ 0.179 0.030 1 .98 101.9'3 :;,: ; q 0. :;_ 88 0. 0 l 1 2.08 102.08 I 0. 191_1 ll. 0 32 2.18 HJ?. l 8 c r: :;-'' . 0.20"/ 0.032 2. 213 102.28 ;';. ll.217 0.033 ?.38 102.:rn ·:-:i::;1;, < 0.226 11.034 2.0 107.47 I r:i/ / :-) . C. 7 3~ 0.035 Talbot H,~hlan~s I '()8 Percola t_ion I cfs I 0. 00 0.00 0.00 0.00 C.00 C. 00 o. no 0.00 0. 00 0. 0 0 0.00 0 . Oil 0.00 0.00 0.00 Cl.Oil 11 . 0 0 0.00 0.00 0 . ll 0 0.00 0.00 0.00 0.00 0.00 :J • () () 0.00 0.00 C.00 0.00 0.00 0. 00 Dl"I 07764 ) • r_:) 7 102. 5-,i 1 '.II' i) 0 . ? 4 4 0.035 0.00 7.. 6 7 1 n. 67 1 0. ;,i 1 )4 0.03G 0.00 2. 77 102. Fi . 1 .11 ' IJ.7.63 0.037 O. rJO 2.87 102. fJI l ·; }, ,,:: / . :). 2"7 3 0.037 0.00 2. 97 10).9/ ]), 'i(,. 0.282 0.038 IJ.OIJ 3 , ll I 103.07 L' ! I ('1. 0.292 c.o:~9 0.00 :~ . -; 7 ~03.17 1 i' '' 0.301 0.039 0.00 3. 27 103.27 I ) '.' 1.H. 0. 3 "1 1 0.040 0.00 3.37 103.3"1 J \'1',? 0.320 0.040 o. 00 3.45 l:J3. 4 '.i J !] / }1 l. O .. J2 B 0.041 C. O IJ 3.46 103.46 '. ·1 )'•/] 0.329 0. 011 0.CO 3. 4 fJ 103.48 } ,'] :1 (i"/ 0. 33] 0.041 0. 00 3.49 103.49 J ,1 /. 1] '·) . 0. 332 0. 04 :J 0. IJO 3.51 103.51 1 ,1,, I Cl. J]/i 0.048 0.00 1.52 103.52 1 '1 :; i -~ . 0. j 3~) 0.051 0.00 3.54 ~ 0 3. 51,, J ;; Ci~' r; . 0. 336 r,. 05 6 0.00 3.55 103.55 ] !, C',' I . C.D7 0.058 0.00 3.57 103.5'7 J l ,; s n. 0.339 0.060 0.00 3.67 103. 67 ]_ ~ 1 '.) 1] 0.349 0. 067 O.OIJ 3.11 103. 77 ' 1-, G'.'1 q. 0.358 0. 073 ll.00 3.87 103.87 -: (;C ,-: ? . 0.368 0.078 0.00 3.97 103. 9"/ ,: d~ 0.377 0.082 0.00 4.07 104. 07 ] ( p 1·) (',. D.387 O.OB6 0.00 4 .11 104. 1 7 l / ;-(; .~ 0. 396 0.090 IJ.IJIJ 4.77 104.27 1 / r) :' r, . 0, 4 06 IJ. 093 0.00 4.37 104.37 -1 P (i ')). 0 . -1 J .'J 0.097 o.oc 4.47 104.1i J fs '1 I' l) . 0.425 0.100 0.00 4, 57 101.57 _l p ')) Cl • 0. 4 34 0.103 0.00 4.67 104. 67 l " l -~ .-1 0.444 0.106 0.CO 1 . .-/ "/ 104. 77 C) / / ;! . 0, 4 5 3 Cl.-, 09 0.00 4.87 104.87 'i I (,/. 0. 4 63 0 .112 0.00 t,. 97 104.9/ '.).-;,'/,:). 0. 4 72 0. 114 0.00 5.00 10',.0C :·:--.inr:, 0. 475 0. ll.5 0. 0 0 DCI 07764 Duralion Comparison _A.:1ayL,is Base File: Pxist.tsf New t''ile: rdout.tsl ::-:,itoff Units: Discha.r~:e in c1:.· Cc.to-:"f 0. Cl4 0 ll.848 Ll. O:i 6 0.065 0.073 0.081 0.090 0. 09[1 0. 10 Ei 0 _ : 15 n. 123 0.131 0.140 0. 14 U -----Fraction cJ[ Base ~cw 0. 69E-ll7 C. 34F:-·1; 0. 52E.-(J;! 0. 23~-::. 0.39F.-0? 0.22E-C? 0.29F:-0) 0.1-8£-('1) IJ.?OF:-02 O.l2F.-i:i 0.14E-02 O.U6F.-i1' O.llb-02 ll.67E-~1 O.BSE-03 0.39~-~, 0.57E-03 0.23E-r;·i 0.46S-03 0.33E-114 ll.lRE-03 J.16E-04 O.llE-03 0.16F.-04 0.4%-04 0.16E-V 0.16E-D4 0.16E-::, ----------~t1eck of Tolerancp------ .. i-. , ,,,,~ Probuhilily Base New ?,Change I 0.69E-02 0.040 0.036 -9.9 _,;0 l I o.57~-02 0.018 0.()37 -22.9 -l ·.7 I 0.39E-02 ll.0~6 C.039 -30.8 so.· I 0.29b-02 o.06~ 0.040 -38.2 -'I.: I 0.20E-02 0.013 0.060 -17.6 -\0 •1 I 0.14E-0? 0.081 0.069 -1~.0 -·1 _1 C O.l:E:-07 0.090 0.076 -15.7 -'i <, J: o.n~iF-03 0.098 0.082 -16.4 -(:,:") .1· 0. :-1 7E-·0.3 0. 106 0.093 -13. 0 n. 4fic-03 (). .1 l.~ Cl. Cl% -16.0 -'.'1,:J. I C. 18E-IJ3 [). 173 0. 109 -11.4 -Pi·,. o. llE-rn [J. 131 0. 112 -H . 8 --(1 (, -0.492-04 0 .140 0. ]14 -18.7 (:1. :J 0. 16f"-04 O.H8 0.158 6.7 Maxj_murn positive excursio~1 = n.111(: -1-s ( 5_g~,) occurring at 0.~~48 cfs on th1·, 11,:::n il.iLa:exist.t::,·[ anrl. at 0.:.58 cf.son the ))e:1;,.1 1·1.:1t.·i: 1· Jc:ut .. tsf Maximum negative exr:urs_;__on =--(',_1:/c·, r'fS (-40.2%) occurring al 0.069 cfs on tri,~ n,-i.'::-. l·.:-ila:exist.tsf and at 0.011 c+s en lhe Ne",' :1,·1:;1: ·,:,·iut..tsf As shown in the previous table, the outlet is below the predevelopment curve at the first cutoff; no excursion exceed positive 10%: and over half of the excursions are less than zero. Therefore, the KCRTS Level 2 Flow Control (1998 KCSWDM) standard has been met. A comparative plot showing vault outlet and target duration curves is included on the following page. Talflot l!,ghlands 1 '0 .'08 DCI 07764 • • • • •. • • i • • ! • • 1• • I • • ' • •' • O'.'. g( 0 t, l 0 n·o 0(0 80 0 (S,J'.)) 8618~'.JSIQ • • I • i • I I •• • j, Ii I o. Oj 90'0 ' ld O vo·o I 00 0 0 0 0 ':' 0 ~ '7 0 ,. 0 ~ "i 0 ~ (I) () C (I) "O (I) (I) () X w -~ ·-D ro D e (L Part E -Water Quality System Water Quality shall be required fr,r this project because it will produce more than 5,000 square feet of new impervious subject to vehicle traffic (PGIS ). Biofiltration is not practical due to the depth or the detention vault. Renton allows wetvaults where protection of ground water is concerned. A wctvault is being proposed instead of a biofiltration swalc to provide water quality. The wetvault will treat the runoff as well as a biofiltration swale while being located underground. The underground wetvault will result in an aesthetically pleasing development and will produce more recreational space that would otherwise be taken up by the hioliltration swalc. The wetvault shall be combined with the detention vault located in Tract A. Preliminary wetvault sizing calculations have hcrn shown on the following page. DCI OTl(,4 WETVAUL T SIZING 07764: Talbot Heights ENTER VALUES INTO THE SHADED CELLS: The following procedure is outlined on page 6-70 of the 2005 KCSWDM: Step 1: Step 2 Step 3: f = 3 Using Figure 6.4.1 A R= R= 0.47 0.039 inches feet A= 50,238 sf Atg = 40,715 sf At1= 0 sf Ao= 0 sf V = ' [ (0 9)A, + (0.25)A1g + (0.10)A,, + (0.01)A, 1 • R Vr= 2,170 cf Vb= f"' Vr Vb= 6,509 cf 5 feet 63 feet 21 feet 6,615 cf, which exceeds the required volume of 6,509 cf. Page 1 07764 Wetvault Sizing xis 5. Conveyance System Analysis and Design Talbut Highlnnds I -('8 DCI 07764 5. Conveyance System Analysis and Design This section shall be provided at the linal engineering stage. lalhot fli~hlands l'·Ol\ nnonM 6. Special Reports and Studies Talbot Hi~hlands t 2'08 DCJ 07764 6. Special Reports and Studies A gcotechnical report has been prepared and included with this submittal. DrJ 077M 7. Other Permits Tnlhnt llighl~nds 1 '-'08 DCI 07764 7. Other Permits This section shall be provided at the final engineering stage. Talbot H,.1chl1.nds DCI ()7764 8. CSWPPP Analysis and Design Talbot llighlauds IJrl\l/7(,4 8. CSWPPP Analysis and Design This section shall be provided at the final engineering stage. Talbot H1~hl~n<l, 1 "2/08 DCI 0776"- 9. Bond Quantities, Facility Summaries, and Declaration of Covenant T albol I f,ghbnrls 1:2/08 DCI 07761 9. Bond Quantities, Facility Summaries, and Declaration of Covenant This section shall be provided at the linal engineering stage. rs'.hot Highland~ I .'iO~ DC! 07761 10. Operations and Maintenance Manual Talbot Highbnds 1 ~ 08 IJ("J 077(,4 10. Operations and Maintenance Manual The City of Renton will assume mainLcnancc and operation responsibilities. DC! 07764