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Home My WebLink AboutMiscGTC #13-115 Reserve at Renton Traffic Impact Analysis TABLE OF CONTENTS I- DEVELOPMENT IDENTIFICATION ....................... 2. METHODOLOGY........................................................ 3. TRIP GENERATION .................... _............................. 4. TRIP DISTRIBUTION ................................................. 5. INTERSECTION LEVEL OF SERVICE ANALYSIS 5.1 Turning Movement Calculations ............................ 5.2 Level of Service Calculations ................................ 6. TRAFFIC MITIGATION FEES ................................... 7. CONCLUSIONS.......................................................... LIST OF FIGU Figure 1: Site Vicinity Map ............................................ Figure 2: Development Trip Distribution PM Peak -Hour Figure 3: 2013 Existing Turning Movements__ ............. Figure 4: 2016 Baseline Turning Movezn s .................. Figure 5: 2016 Future with Developme over Table 1: Level of Service Criteria ................. Table 2: Trip Generatio ............. Table 3: Level of Se Table 4. Traffic on Fee S ary .... Trip Generation ........I .................. I.... Calculations ........... ..................... ..................... ............................ .........I 1 .................................. 5 .......................... 7 ...................................... 9 Gibson Traffic Consultants, Inc. December 2013 info@gibsontraffic.com i GTC #13-115 Reserve at Renton Traffic Impact Analysis 1. DEVELOPMENT IDENTIFICATION Gibson Traffic Consultants, Inc. (GTC) has been retained to provide a traffic impaalysis for Reserve at Renton development. This report is intended to provide the City of, with the necessary traffic generation, trip distribution and intersection analysis to faci '```` eir review of the development. The Reserve at Renton Hotel is proposed to include 219d senior housing units with 5,431 square -feet (SF) of retail space. The development is a een Rainier Avenue S and Hardie Avenue SW within the Fred Meyer retail area."velopin' roposed to have access to Rainier Avenue S at the S 41h Place signal an o rdie Avenu via the existing driveway at 5th Place SW. A site vicinity map is inclu igure 1. Brad Lincoln, responsible for this report and traffic (Civil) in the State of Washington and member of the 2. METHODOLOGY rs a licensed professional eng ton State,�ion of ITE. The analysis contained in this report is on scoping disc The intersections that provide access t ment, Ra. Hardie Avenue SW at 51h Place SW, hav n a arl lqmw analysis has been performed in accordan ith the Congestion is generally measured in to f le intersections are rated betw LOS A and L LOS A bey g free flow and LOS F being forced flow or over-ca ions. A su of the level of service criteria is included in Table 1. Gibson Traffic Consultants, Inc. December 2013 info@gibsontraffic.com 1 GTC #13-115 SW SUNSET BLVD w a S M ST N AIRPORTMY 5 W } a z I GIBSON IC CONSULTANTS TRAFFIC IMPACT STUDY GTC #13-115 RESERVE AT RENTON I LEGEND FIGURE 1 219 SENIOR ADULT HOUSING ® DEVELOPMENT SrrE SITE VICINITY 5,431 SF SPECIALTY RETAIL MAP CITY OF RENTON sTuoYlrrrERsec�ONs Reserve at Renton Traffic Impact Analysis Table 1: Level of Service Criteria Level of I Expected Service Delay A Little/No De 13 Short Dela, C Average Del D Long Dela E Very Lons Df The trip generation calculations for published in the Institute of Transpc (2012). t Source: 2010. Intersection Control Delay (Seconds per Vehicle) Unsignalized and Roundabout Intersections <10 >10 and <15 >15 and <25 >25 and <35 >35 and <50A _ and <33 >35 and <55 >55 and <80 >80 taverage delay for tHE way stop -controlled r all vehicles. The level performed utilizing the based on trip generation rates rip Gen e Manual, V' Edition LOS A: Free -flow conditions, with minimal delay to stopped vehicles (no vehicle is delayed longer than one c t signalized intersection). S: Generall a traffic flow conditions. Occas' ack-ups may develop, but delay to vehicles is short term and still tolerable. L u ' rt periods of the peak hour, delays to approaching vehicles may be substantial but are e during times of less demand (i.e. vehicles delayed one cycle or less at signal). LOS E: sections operate at or near capacity, with long queues developing on all approaches and long LOS F: Jammed conditions on all approaches with excessively long delays and vehicles unable to move at times. 2 when demand volume exceeds the capacity of the lane, extreme delays will be encountered with queuing which may cause severe congestion affecting other traffic movements in the intersection. Gibson Traffic Consultants, Inc. December 2013 info@gibsontraffic_com 3 GTC 413-115 Reserve at Renton Traffic Impact Analysis 3. TRIP GENERATION Trip generation calculations for the Reserve at Renton development have been performed utilizing data published in the Institute of Transportation Engineers (ITE) Trip Generatio Manual, 9 h Edition, Volume 2: Data (2012). The average trip generation rates for ITE Lan. Cade 252, senior adult housing - attached, and ITE Land Use Code 826, specialty ret ' er, have been used for the trip generation calculations. Additionally, pass -by trips h . calculated to account for vehicles currently using the Rainier Avenue S that will cialty retail portion of the development. These trips are therefore not new trips addeJ adjacent roadway. The pass -by percentage is based on the industry standar f %. It is imp o note that this pass -by percentage is lower than similar retail land us h as shopping cen ich has a pass -by percentage of 34%. The trip generation of the m Renton Hotel devel t is summarized in Table 2. Table 2: Trip Use Size Average M Peak -Hour InbMIM& Outbound Total Daily Trips Senior Adult Rousing —Attached ITE LUC 525 219 units &WL_ 30 25 L 55 Specialty Retail Center ITE LUC 526 5,431 SF 24 5 !%� 11 Specialty Retail Center (Pass -By Reduction 0 2 -4 TOTAL gg1flbh, Iffia 35 31 1 66 Gibson Traffic Consultants, Inc. December 2013 info@gibsontraffic.com 4 GTC #13-115 ' AIRPORTMYS s � iA - 1 e at i 2� sa f 003 F 3 47 .S I� $�i f 3` � 7► ��2� t J 140 I T46 ��J�y 2 SUNSET BLVD t� 2`LOCALPL N bk 2 SIT 47 ►2 S TfH ST QU1 a W d 4 2 I N 12RW13 GIBSON IC CONSULTANTS TRAFFIC IMPACT STUDY GTC #13-115 RESERVE AT RENTON LEGEND FIGURE 2 219 SENIOR ADULT HOUSING NEW SITE TRAFFIC Pm t ) PEAK InNLYIPEAKHOUR} DEVELOPMENT TRIP 5,431 SF SPECIALTY RETAIL __, DISTRIBUTION lei TFUP DiSTRS"ON % PM PEAK -HOUR CITY OF RENTON J future with develgWt turning iffilements are Reserve at Renton Traffic Impact Analysis 5. INTERSECTION LEVEL OF SERVICE ANALYSIS During the scoping process with City of Renton staff it was determined that the adjacent intersections of Rainier Avenue S at S 41" Place and Hardie Avenue SW at 5`" a12tce SW are required to be analyzed. The intersection of Rainier Avenue S at 41" Place 5IF signalized intersection and was recently improved as part of the Rainier Avenue S impra € att project. The �� .T,. intersection of Hardie Avenue SW at 51" Place SW is a two-way stop -con tersection with 5`" Place SW, and the driveway providing access to the development, h -control. 5.1 Turning Movement Calculations The existing PM peak -hour turning movements at the inter Place have been obtained from the City of Renton and ar due to the construction along the route. The existin e; intersection of Hardie Avenue SW at 5'h Place SW Ile( IDAX in August 2013. The existing turning movemen Figure 3. It is important to note that northbound left -turn, turn volumes have been estimated for the 2013 existing condit when the counts were collected, but are jAkwailable with the ng the y 14 and therefore the 2016. line ruing movements have rmeents, o the 2013 existing fuming tudy intersections are shown in Figure at the study intersections have been 2016 baseline turning movements. The 2016 vn in Figure 5. Gibson Traffic Consultants, Inc. December 2013 info@gibsontraffic.com 6 GTC #13-115 AAA---- 14 SW SUNSET BLVD GIBSON IWIC COI RESERVE AT RENTON 219 SENIOR ADULT HOUSING 5,431 SF SPECIALTY RETAIL lei i fire] a 0 4 z ff47k, I AIRPORT MY S 9 LEGEND FIGURE 3 PM PEAK4MR TURNING MOVEMENTS 2013 EXISTING TURNING MOVEMENTS r r Qy9 AIRPORTMYS _33 r '', • 12a 16= N S. SW SUNSET BLVD GIBSON S TTH ST CONSULTANTS RESERVE AT RENTON 219 SENIOR ADULT HOUSING 5,431 SF SPECIALTY RETAIL CITY OF RENTON ti LEGEND PIN PEAK -HOUR TURNING MOVEMENTS w a z_ 9 N 12W13 TRAFFIC IMPACT STUDY GTC #13-115 FIGURE 4 2016 BASELINE TURNING MOVEMENTS i AIRPORT MY S N S 7TH ST 9 GIBSON IWIC CONSULTANTS RESERVE AT RENTON LEGEND 219 SENIOR ADULT HOUSING 5,431 SF SPECIALTY RETAIL CITY OF RENTON PM PEAK-HDIJR TURMNG MDVEMENTS W a z I N 12W13 TRAFFIC IMPACT STUDY GTC #13-115 FIGURE 5 2016 FUTURE WITH DEVELOPMENT TURNING MOVEMENTS Reserve at Renton Traffic Impact Analysis 5.2 Level of Service Calculations The level of service calculations have been performed utilizing the existing channelization and intersection control, including the Rainier Avenue S improvements. The paramethave been used for the 2013 existing, 2016 baseline and 2016 future with development con ti s. The level of service summary is summarized in Table 3. Table 3: Level of Service Summary 2013 Existing 2016 Baseline V2016 Futu Intersection Conditions Conditions Development Con LOS Delay LOS D LOS Dela 1. Rainier Avenue S at S 4'h Place B 13.8 sec B sec B Al 19.1 sec 2. Hardie Avenue SW at Site Access C 22.6 sec D 7.1 sec 30.1 sec The analysis shows that the addition of the Reserve at ReNo pment will add less than 3 seconds of delay at the study intersections and will not Chael of service from the 2016 baseline conditions. The operations of intersectiorefore be acceptable. The level of service calculations are include ent 6. TRAFFIC MITIGATION FEES The level of service a that the stl and Hardie Avenue 5t�` W will channelization a trol, with Reserve development therefore a conditi development a require mitigation fee. n rsections of Rainer Avenue S at S 41h Place acceptably with the existing configuration, iton development. The Reserve at Renton � provide any off -site improvements. The riate City of Renton transportation impact tcts fees are summarized in Table 4. 4: Traffic Mitigation Fee Summary The Res enton will have transportation impact mitigation fees of $87,242.57, based on the current fees. Gibson Traffic Consultants, Inc. December 2013 info@gibsontraffic.com 10 GTC #13-115 Reserve at Renton Traffic Impact Analysis 7. CONCLUSIONS The Reserve at Renton development is proposed to consist of 219 senior adult housing units and 5,431 SF of retail space. The development is anticipated to generate 934 average _ trips with 66 PM peak -hour trips. The development is not anticipated to cause the of T sections of Rainier Avenue S at S 4th Place and Hardie Avenue SW at 5`h Place Sj at a deficient level of service and should therefore not be conditioned to provide any oovements. The current transportation impact mitigation fees total $87,242.57 for the de Gibson Traffic Consultants, Inc. December 2013 info@gibsontraffic.com 11 GTC #13-115 FrEdMoyer To: Christopher Santoro c/o Arvin Vander Veen Colliers International 601 Union Street, Suite 5300 Seattle, WA 98101 Re: Renton Center, Renton WA OFC Quality Food Centers Fred Meyer Stores, Inc., is the successor by merger as Declarant under the Declaration of Covenants, Conditions, Restrictions and Easements governing the Renton Center Fred Meyer development in Renton, WA, recorded under document 9904062560 in the King County .real estate records (the "Declaration"). This letter documents the consent of Fred Meyer Stores, Inc., as declarant, to construction of an adult residential facility on Parcel D of the development (as depicted on Exhibit 2 to the Declaration), on the condition that the development will be constructed substantially as depicted on the site plan and elevations attached to this letter. Yours Truly, Robert Currey -Wilson V.P., Real Estate Director Fred Meyer Stores, Inc. 0% EMIBIT 2 Site Plan Drawing D [H Wutl�Yrr 2 k | ,| % /7 �• % § §||§ t .�� i; - : ||� � � � - m =1l� i ;/,■§ HM i $ ,,Mxi §MS || A +v31oAN (f ) ) wii R ■ - � � . . � O � | | � m || m | [ | ��( � GEOTECHNICAL ENGINEERING REPORT PROPOSED RENTON SENIOR LIVING PROJECT 325 RAINER AVENUE SOUTH RENTON, WASHINGTON Project No. 1187.01 December 11, 2013 Prepared for: Canddle Development Prepared by: ZGA Zipper Geo Associates, LLC Geotechnical and Environmental Consultants 19023 361h Avenue W., Suite D Lynnwood, WA 9803 Zipper Geo Associates, LLC Geotechnical and Environmental Consulting Project No. 1187.01 December 11, 2013 Canddle Development 3424 Via Oporto, Suite 201 Newport Beach, CA 92663 Attention: Mr. Christopher Santoro Subject: Geotechnical Engineering Report Proposed Renton Senior Living Project 325 Rainer Avenue South Renton, Washington Dear Mr. Santoro: In accordance with your request and written authorization, Zipper Geo Associates, LLC (ZGA) has completed the subsurface explorations and geotechnical engineering evaluation for the proposed Renton Senior Living project located at 325 Rainer Avenue South in Renton, Washington. This report presents the findings of the subsurface exploration and geotechnical recommendations for the project. Our work was completed in general accordance with our proposal (Proposal No. P13215) dated July 31, 2013. Written authorization to proceed was provided by you on August 16, 2013. We appreciate the opportunity to be of service to you on this project. If you have any questions concerning this report, or if we may be of further service, please contact us. Sincerely, Zipper Geo Associates, /?d44,-f' -A Robert A. Ross, P.E. Principal Copies: Addressee (1) CG Engineering —Chevy Chase (1) 3 V14 G. John E. Zipper, P.E. Managing Principal 19023 3616 Avenue West, Suite D Lynnwood, WA 98036 (42S) 582-9928 k TABLE OF CONTENTS INTRODUCTION............................................. .... ..................................................................................... 1 PROJECT UNDERSTANDING ..................... ...... ........................................................................................ 1 SURFACECONDITIONS ...................................................................................... ...................................... i SUBSURFACE CONDITIONS ...................................................................................................................... 2 RegionalGeology ................................................................................................... ...... --...................... Z SoilConditions ................................................................................................................ ----...... '—...... 2 Groundwater Conditions ----_-------------------_--------........ 3 Summary ofLaboratory Testing ..................................................................................................................... 4 CONCLUSIONS AND RECOMMENDATIONS ............................................................................................ 4 General........................................................................... --... ............................................................. 4 Seismic Design Considerations ................................................................... —...... —... ... ............................. 4 SitePreparation ............................................................................................................. ...... ---......... ...... Structural Fill Materials and Preparation .......................................................................................... ----8 ConstructionDewa*er|ng--....................................................................................................................... zz UndergroundUtilities .................. ---................................................................................. ................. zz Temporary and Permanent Slopes .......................... -----...................................................................... l2 BuildingFoundation Support ................................. -----......... ............................................................ 13 _______AvAprCast`inrPlaceConcrete Piles ........................................................................... ---... .... 1J ACPPile Construction Considerations ------------_----------------.zu GroundImprovement ............................................................................ ------..................... 13 Building On -Grade Concrete Floor Slab ................................................................ ------... .............. 17 ouc0|UedPermanent Retaining Walls .......................................................................................................... 17 Pavement............................................................. ..... ......... ... --................................................... 19 Figure 1—Site and Exploration Plan APPENDICES Appendix A—SubsurfaceExplorationPrqcmduresandLogx Cover Photo Credit; Google Earth GEOTECHNICAL ENGINEERING REPORT 17:Z6106114 1111.14 ► 111 Eel z 11 Q I [*I ZIA L1FI I � 1012 .T6I1twill 325 RAINER AVENUE SOUTH RENTON, WASHINGTON Project No. 1187.01 December 11, 2013 10 `111:1611111111y IIrel0 This report documents the surface and subsurface conditions encountered at the site and our geotechnical engineering recommendations for the proposed Renton Senior Living project located at 325 Rainer Avenue South in Renton, Washington. The project description, site conditions, and our geotechnical conclusions and design recommendations are presented in the text of this report. Supporting data including detailed exploration logs and field exploration procedures, results of laboratory testing and other supporting information are presented as appendices. Our geotechnical engineering scope of services for the project included a literature review, site reconnaissance, subsurface exploration, laboratory testing, geotechnical engineering analysis, and preparation of this report. The subsurface evaluation consisted of completing three geotechnical test borings and four electronic cone penetrometer (CPT) tests. PROJECT UNDERSTANDING We understand the project will consist of constructing a five story mixed use building and associated site improvements on a 3.67 acre property located at 325 Rainer Avenue South in Renton, Washington. The lower floor of the proposed building will include about 34,000 square feet of senior apartment space and about 5,430 square feet of commercial space. The remaining floors will include about 31,000 to 36,000 square feet of senior apartment space. Areas surrounding the site are currently developed and relatively flat. As a result, we expect finished floor elevation for the new building will be within about a foot of existing site grades. We also expect mass grading for the project to be relatively minimal with cuts and fills of 2 feet or less. We understand that detention of stormwater runoff from the site will not be required as there is existing infrastructure in place. However, we expect new stormwater collection systems as well as other underground utilities will be constructed as part of the project. The project will also include new asphalt pavements. SURFACE CONDITIONS The project site consists of a 3.67 acre property located at 325 Rainer Avenue South in Renton, Washington. The site is bordered to the north by developed commercial property; to the south by BNSF railroad right-of-way; to the east by developed commercial property; and to the west by Hardie Avenue Southwest. The project site is generally level with areas of gravel surfacing and areas of paved surfacing. Page 1 Zipper Geo Associates, LLC Proposed Renton Senior Living Project Project No. 1187.01 December 11, 2013 There are existing, abandoned and active underground utilities at the project site. Additionally, there are high tension power transmission lines that cross the east portion of the site from north to south. The project site is illustrated on the attached Figure 1, Site and Exploration Plan. SUBSURFACE CONDITIONS Regional Geology We assessed the geologic setting of the site and the surrounding vicinity by reviewing information published on the Washington State Department of Natural Resources' (DNR) Subsurface Geology Information System website (https://fortress.wa.gov/dnr/geology/?Theme=subsurf ). The DNR website indicates the site is underlain by Holocene aged Alluvium deposits. The alluvium deposits are described as moderately well sorted deposits of cobble gravel, pebbly sand, and sandy silt. Soil Conditions The subsurface evaluation for this project included three geotechnical borings and four electronic cone penetrometer tests (CPTs). Boring B-1 was completed to a maximum depth of about 51.5 feet below existing site grade. Borings B-2 and B-3 were completed to a maximum depth of about 11.5 feet below existing site grades. CPT-1 through CPT-4 were completed to maximum depths ranging from about 25 to 28.5 feet below existing site grade. The approximate exploration locations are shown on the Site and Exploration Plan, Figure 1. Soils observed in the borings were visually classified in general accordance with the Unified Soil Classification System. Descriptive logs of the subsurface explorations and the procedures utilized in the subsurface exploration program are presented in Appendix A. A generalized description of soil conditions encountered in the borings is presented below. Detailed descriptions of soils encountered are provided on the descriptive logs in Appendix A. The description of soil conditions encountered in the CPT explorations presented below is based on measured values of cone tip resistance and sleeve friction, presented as a Friction Ratio, and pore water pressure relative to the theoretical hydrostatic groundwater pressure, presented as a pore pressure ratio. It should be noted that the description of soils is based on empirical correlations. No actual physical soil samples were obtained or observed as part of the CPT explorations. It should be noted that the term "description" used here does not refer to a standard classification system such as the Unified Soil Classification System. The use of CPT should be considered to provide an assessment of soil behavior type and an indirect assessment of soil "description". Boring B-1 was completed in the central portion of the proposed building footprint. Subsurface soil conditions observed in boring B-1 generally consisted of about 8 inches of crushed rock fill underlain by gravelly sand fill extending to about 1.5 feet below existing site grade. Very loose sand with trace silt was observed below the gravelly sand fill extending to about 4 feet below existing site grade. Soil conditions observed below the very loose sand generally consisted of very soft silt and very loose sand extending to about 25 feet below existing Page 2 Zipper Geo Associates, LLC Proposed Renton Senior Living Project Project No. 1187.01 December 11, 2013 site grade. Medium dense to dense gravel with a variable sand content was observed below the very loose sand and very soft silt to the completion depth of about 51.5 feet below existing site grade. Borings B-2 and B-3 were completed in the eastern proposed parking area. Subsurface soil conditions observed in these borings generally consisted of about 3.5 to 4 inches of asphalt concrete pavement underlain by about 8 inches of crushed rock fill. Soil conditions observed below the pavement section generally consisted of very loose sand with variable silt content and soft silt with trace to some peaty organics extending to about 10 feet below the existing ground surface. Both borings were terminated at about 11.5 feet below the existing ground surface in medium dense sand. CPTs 1 through 4 were completed within the proposed building footprint. Due to dense ground conditions within the upperfewfeet of existing site grades, the first few feet of CPTs were "pre -drilled" using hand tools. As a result, CPT data acquisition began at about 5 feet below existing site grade in CPT-1 and about 2 feet in CPT-2 through CPT-4. Surficial soil conditions observed in the "pre -drilled" range of the CPTs consisted of the following: • CPT-1: 1 inch of asphalt concrete pavement underlain by about 4 feet of sand and gravel fill underlain by sand. • CPT-2: 1 inch of asphalt concrete pavement underlain by about 8 inches of crushed rock fill underlain by sand. • CPT-3: 8 inches gravel underlain by sand. • CPT-4: 3 inches of asphalt concrete pavement underlain by 6 inches of crushed rock fill underlain by sand. Below the "pre -drilled" range, soil behavior types indicated by the CPTs within approximately the upper 20 feet of existing site grade were considerably variable and consisted of sensitive fine grained, clay, silty clay to clay, clayey silt to silty clay, sandy silt to clayey silt, silty sand to sandy silt, and sand to silty sand. Recorded tip resistance in the upper 20 feet of existing site grade was typically below 50 tons per square foot (tsf). It should be noted that recorded tip resistances in some of the CPTs within the upper 10 to 15 feet of existing site grades was extremely low (less than 10 tsf) indicating very soft, sensitive fine grained soil behavior type. From about 20 feet to the completion depths of 25 to 28 feet below existing grade, soil behavior types indicated by the CPTs typically consisted of sand and gravelly sand. Tip resistance quickly increased below 20 feet and ranged from about 50 tsf to refusal values in excess of 250 psf. Groundwater Conditions Groundwater was observed in all borings completed for this study. Groundwater monitoring wells were installed in all the borings. Groundwater was measured in each well on October 10, 2013 and the measured depths below existing ground surface (bgs) were as follows: Page 3 Zipper Geo Associates, LLC Proposed Renton Senior Living Project Project No.1187.01 December 11, 2013 • Boring B-1: Groundwater measured at 6.2 feet bgs. • Boring B-2: Groundwater measured at 6.5 feet bgs. • Boring B-3: Groundwater measured at 6.6 feet bgs. Groundwater observed in the explorations is interpreted to be a regional shallow aquifer within the alluvial soil unit. The thickness of the saturated zone of this shallow aquifer is unknown. Fluctuations in groundwater levels will likely occur due to seasonal variations in the amount of rainfall, runoff and other factors not evident at the time the explorations were performed. Therefore, groundwater levels during construction or at other times in the life of the structure may be higher than indicated on the logs. The possibility of groundwater level fluctuations should be considered when developing the design and construction plans for the project. Summary of Laboratory Testing Limited laboratory testing was completed on selected samples obtained from our borings. The testing consisted of moisture content on select samples. Moisture content of samples tested from the upper 10 feet of existing site grades in borings B-2 and B-3 indicated moisture contents ranging from 13 to 37 percent. Results of moisture content testing are shown on the boring logs provided in Appendix A. CONCLUSIONS AND RECOMMENDATIONS General Soil conditions observed in geotechnical explorations completed for the project are not suitable for shallow foundation support. As a result, we recommend the proposed building be supported on deep foundations such as auger cast piles or alternatively, the loose soils observed in the explorations could be improved with aggregate piers such as the proprietary Geopier system or stone columns. Specific geotechnical engineering recommendations for foundation systems and other earthwork related phases of the project are outlined below. The recommendations contained in this report are based upon the results of field and laboratory testing (which are presented in Appendices A and B), engineering analyses, and our current understanding of the proposed project. ASTM and Washington State Department of Transportation (WSDOT) specification codes cited herein respectively refer to the current manual published by the American Society for Testing & Materials and the current edition of the WSDOT Standard Specifications for Road, Bridge, and Municipal Construction, (M41-10). Seismic Design Considerations The tectonic setting of western Washington is dominated by the Cascadia Subduction Zone formed by the Juan de Fuca plate subducting beneath the North American Plate. This setting leads to intraplate, crustal, Page 4 Zipper Geo Associates, LLC Proposed Renton Senior Living Project Project No. 1187.01 December 11, 2013 and interplate earthquake sources. Seismic hazards relate to risks of injury to people and damage to property resulting from these three principle earthquake sources. The seismic performance of the development was evaluated relative to seismic hazards resulting from ground shaking associated with a design seismic event as specified in the 2012 International Building Code (IBC). Conformance to the above criteria for seismic excitation does not constitute any kind of guarantee or assurance that significant structural damage or ground failure will not occur if a design seismic event occurs. The primary goal of the IBC seismic design procedure is to protect life and not to avoid all damage, since such design may be economically prohibitive. Following a major earthquake, a building may be damaged beyond repair, yet not collapse. The results of our seismic hazard analyses and recommended seismic design parameters are presented in the following sections. Ground Surface Rupture: Based on our review of the USGS Quaternary age fault database for Washington State, there does not appear to be a mapped Quaternary fault within a 10 mile radius of the site. Based on the reviewed database, the risk of ground surface rupture at the site appears to be low. Landslidine: Based on the relatively flat topography of the site and surrounding vicinity, the risk of earthquake -induced landsliding is low. Soil Liquefaction: Liquefaction is a phenomenon wherein saturated cohesionless soils build up excess pore water pressures during earthquake loading. Liquefaction typically occurs in loose soils, but may occur in denser soils if the ground shaking is sufficiently strong. The potential hazardous impacts of liquefaction include liquefaction -induced settlement and lateral spreading. ZGA completed a liquefaction analysis based on ground motion design parameters as specified in the 2012 International Building Code. Specifically, our analysis used the following ground motion parameters. • PGA = Sos/2.5 = 0.389 • Earthquake Magnitude = 7.0 Our liquefaction analysis was completed in general accordance with the "simplified procedure" as outlined in Liquefaction Resistance of Soils: Summary Report from the 1996 NCEER and 1998 NCEER/NSF Workshops on Evaluation of Liquefaction Resistance of Soils (Youd and Idriss, 2001). Soils observed boring B-1 between about 25 feet below existing site grade and the completion depth of about 51.5 feet consisted of medium dense gravels with very little fines content. It is our opinion that the risk of liquefaction in the gravels below 25 feet is low. Our opinion regarding the risk of liquefaction in gravels below 25 feet is based on measured shear wave velocity obtained in CPT-3 at a depth of 22 feet. The measured shear wave velocity at 22 feet in CPT-3 was approximately 900 feet per second (ft/sec). The overburden stress -corrected shear wave velocity in accordance with equation 21 (Youd and Idriss, 2001) is approximately 950 ft/sec. Figure 9 of Youd and Idriss, 2001 indicates that no liquefaction has Page 5 Zipper Geo Associates, LLG Proposed Renton Senior Living Project Project No. 1187.01 December 11, 2013 been observed at sites with overburden -corrected values of shear wave velocity greater than about 650 ft/sec. Shear wave velocities in CPT-3 were determined through seismic cone penetration tests (SCPT) completed at specific intervals. The results of SCPT testing are provided in Appendix A. Our liquefaction analyses indicates that the risk of liquefaction in zones of soil below the groundwater table within the upper 25 feet of existing site grade is high. We estimate that liquefaction -induced settlement resulting from IBC ground motions at the site could be on the order of 6 to 12 inches. Liquefaction settlements could result in damage to improvements supported on grade and underground utilities. IBC Seismic Design Parameters: Based on site location and soil conditions, the values provided below are recommended for seismic design. The values provided below are based on the 2012 IBC as the building code reference document. IBC requires a site specific ground motion analysis for sites with liquefiable soils. However, for structures with a fundamental period of vibration equal to or less than 0.5 seconds, site classification may be determined without regard to liquefaction. The values provided below assume the building will have a fundamental period of vibration less than or equal to 0.5 seconds. SUMMARY OF IBC SEISMIC DESIGN PARAMETERS Parameter Value 2012 IBC Site Classification I F 1 S�Spectral Acceleration for a Short Period 1.441 g (Site Class B) 5,Spectral Acceleration for a 1-Second Period 0.539 g (site Class e) Fa Site Coefficient for a Short Period 1.000 (Site Class D) F, Site Coefficient for a 1-Second Period 1.500 (Site Class D) Sens Maximum considered spectral response 1.441 g (Site Class D) acceleration for a Short Period SM1 Maximum considered spectral response 0.S0S g {Site Class D) acceleration for a 1-Second Period 5Ds Five -percent damped design spectral response 0.961 g (Site Class D) acceleration for a Short Period Sol Five -percent damped design spectral response 0.539 g (Site Class D) acceleration for a 1-Second Period 1. In general accordance with the 2012 internotional Building Code, Table 1613.5.2. IBC Site Class is based on the average characteristics of the upper 100 feet of the subsurface profile. The borings completed for this study extended to a maximum depth of 51.5 feet below grade. ZGA therefore determined the Site Class assuming that medium dense alluvial soils extend to 100 feet as suggested by published geologic maps for the project area. Page 6 Zipper Geo Associates, LLG Proposed Renton Senior Living Project Project No. 1187.01 December 11, 2013 Lateral Spread: Lateral spreading is a phenomenon in which soil deposits which underlie a site can experience significant lateral displacements associated with the reduction in soil strength caused by soil liquefaction. This phenomenon tends to occur most commonly at sites where the soil deposits can flow toward a "free -face", such as a water body. Due to the lack of a "free -face" condition, the risk of lateral spreading at the site is low for the IBC design earthquake. Site Preparation Erosion Control Measures: Stripped surfaces and soil stockpiles are typically a source of runoff sediments. We recommend that silt fences, berms, and/or swales be installed around the downslope side of stripped areas and stockpiles in order to capture runoff water and sediment. If earthwork occurs during wet weather, we recommend that all stripped surfaces be covered with straw to reduce runoff erosion, whereas soil stockpiles should be protected with anchored plastic sheeting. Temporary Drainage: Stripping, excavation, grading, and subgrade preparation should be performed in a manner and sequence that will provide drainage at all times and provide proper control of erosion. The site should be graded to prevent water from ponding in construction areas and/or flowing into and/or over excavations. Exposed grades should be crowned, sloped, and smooth -drum rolled at the end of each day to facilitate drainage if inclement weather is forecasted. Accumulated water must be removed from subgrades and work areas immediately and prior to performing further work in the area. Equipment access may be limited and the amount of soil rendered unfit for use as structural fill may be greatly increased if drainage efforts are not accomplished in a timely manner. Demolition. Clearing, and Stripping: We expect some limited clearing and stripping will be completed in areas of existing landscape islands. We recommend all roots and organic rich topsoil be removed from areas where existing landscape islands will be removed. We expect demolition to include removal of existing concrete curbs and other minor existing above ground utility structures. These items should be removed and properly disposed of offsite. Existing asphalt concrete pavement covers a significant portion of the proposed building footprint. The existing asphalt may pose penetration difficulties for deep foundation or ground improvement drilling equipment. We recommend existing asphalt concrete pavements be ground, full depth, and removed from the building footprint. We expect some existing underground utilities will be abandoned as part of the project work. We recommend existing utilities be abandoned by full removal or grouting in place. Subgrade Preparation: Once site preparation is complete, all areas that are at design subgrade elevation or areas that will receive new structural fill should be compacted to a firm and unyielding condition. Once compacted, subgrades should be evaluated through proof rolling with a loaded dump truck or heavy rubber -tired construction equipment weighing at least 20 tons to assess the subgrade adequacy and to detect soft and/or yielding soils. In the event that soft or yielding areas are detected during proof rolling, Page 7 Zipper Geo Associates, LLC Proposed Renton Senior Living Project Project No. 1187.01 December 11, 2013 the upper 12 inches of subgrade should be scarified, moisture conditioned and re -compacted as necessary to obtain at least 95 percent of the maximum laboratory density (per ASTM D1557) and a firm, non - yielding condition. Those soils which are soft, yielding, or unable to be compacted to the specified criteria should be over -excavated and replaced with suitable material as recommended in the Structural Fill section of this report. As an alternate to subgrade compaction during wet site conditions or wet weather, the upper 12 inches of subgrade should be overexcavated to a firm, non -yielding and undisturbed condition and backfilled with compacted imported structural fill consisting of free -draining Gravel Borrow or crushed rock. In the event that wet site conditions preclude proof rolling the subgrade, a ZGA representative should evaluate the conditions via hand probing. Earthwork should be completed during drier periods of the year when soil moisture content can be controlled by aeration and drying. If earthwork or construction activities take place during extended periods of wet weather, exposed site soils will quickly become unstable or not be compactable. In the event the exposed subgrade becomes unstable, yielding, or unable to be compacted due to high moisture conditions, we recommend that the materials be removed to a sufficient depth in order to develop stable subgrade soils that can be compacted to the minimum recommended levels. The severity of construction problems will be dependent, in part, on the precautions that are taken by the contractor to protect the subgrade soils. Freezing Conditions: If earthwork takes place during freezing conditions, all exposed subgrades should be allowed to thaw and then be compacted prior to placing subsequent lifts of structural fill. Alternatively, the frozen material could be stripped from the subgrade to expose unfrozen soil prior to placing subsequent lifts of fill or foundation components. The frozen soil should not be reused as structural fill until allowed to thaw and adjusted to the proper moisture content, which may not be possible during winter months. Structural Fill Materials and Preparation Structural fill includes any material placed below foundations and pavement sections, within utility trenches, and behind retaining walls. Prior to the placement of structural fill, all surfaces to receive fill should be prepared as previously recommended in the Site Preparation section of this report. Laboratory Testing: We recommend that representative samples of proposed imported materials be submitted for laboratory testing at least one week prior to use. Tests completed on the samples should include moisture content, grain size analysis and modified proctor. These tests will provide an indication of the suitability of the material for use as structural fill and an indicator of support characteristics. Reuse of Site Soils as Structural Fill: Soils observed in the geotechnical borings generally contained a significant fraction of fines and appeared wet of optimum moisture content for compaction at the time the explorations were completed. Reuse of site soils site soils as structural fill will only be feasible during Page 8 Zipper Geo Associates, LLC Proposed Renton Senior Living Project Project No. 1187.01 December 11, 2013 dry summer months. Even during dry summer months, site soils will likely require moisture conditioning (drying) in order for reuse as structural fill. During wet weather, we do not expect site soils to be suitable for reuse as structural fill. Soils excavated from below the groundwater table will not be suitable for reuse as structural fill without significant drying or chemical treatment. Drying of over -optimum moisture soils may be achieved by scarifying or windrowing surficial materials during extended periods of dry weather. If encountered, soils which are dry of optimum may be moistened through the application of water and thorough blending to facilitate a uniform moisture distribution in the soil prior to compaction. We recommend that site soils used as structural fill have less than 4 percent organics by weight and have no woody debris greater than Yz inch in diameter. We recommend that all pieces of organic material greater than YZ inch in diameter be picked out of the fill before it is compacted. Any organic -rich soil derived from earthwork activities should be utilized in landscape areas or wasted from the site. Imported Structural Fill: Imported structural fill may be required for raising site grades or for other reasons. The appropriate type of imported structural fill will be mostly dependent on weather and desired support characteristics. During dry weather, lesser quality fill such as Common Borrow can be used. However, during wet weather, higher quality, free draining fill such as Gravel Borrow is typically required. The following paragraphs present general recommendations regarding imported structural fills. During extended periods of dry weather, we recommend imported fill, at a minimum, meet the requirements of Common Borrow as specified in Section 9-03.14(3) of the 2012 Washington State Department of Transportation, Standard Specifications for Rood, Bridge, and Municipal Construction (WSDOT Standard Specifications). During wet weather, higher -quality structural fill might be required, as Common Borrow may contain sufficient fines to be moisture sensitive. During wet weather we recommend that imported structural fill meet the requirements of Gravel Borrow as specified in Section 9-03.14(1) of the WSDOT Standard Specifications. Retaininp, Wall Backfill: Retaining walls should include a drainage fill zone extending at least two feet back from the back face of wall for the entire wall height. The drainage fill should meet the requirements of Gravel Backfill for Walls as specified in Section 9-03.12(2) of the WSDOT Standard Specifications. Moisture Content: The suitability of soil for use as structural fill will depend on the time of year, the moisture content of the soil, and the fines content (that portion passing the U.S. No. 200 sieve) of the soil. As the amount of fines increases, the soil becomes increasingly sensitive to small changes in moisture content. Soils containing more than about 5 percent fines (such as the near -surface on -site soils) cannot be consistently compacted to the appropriate levels when the moisture content is more than approximately 2 percent above or below the optimum moisture content (per ASTM D1557). Optimum Page 9 Zipper Geo Associates, LLC Proposed Renton Senior Living Project Project No. 1187.01 December 11, 2013 moisture content is that moisture content which results in the greatest compacted dry density with a specified compactioe effort. Fill Placement: Structural fill should be placed in horizontal lifts not exceeding 10 inches in loose thickness. Each lift of fill should be compacted using compaction equipment suitable for the soil type and lift thickness. Each lift of fill should be compacted to the minimum levels recommended below based on the maximum laboratory dry density as determined by the ASTM D1557 Modified Proctor Compaction Test. Moisture content of fill at the time of placement should be within plus or minus 2 percent of optimum moisture content for compaction as determined by the ASTM D1557 test method. Compaction Criteria: Our recommendations for soil compaction are summarized in the following table. Structural fill for roadways and utility trenches in municipal rights -of -way should be placed and compacted in accordance with the jurisdiction codes and standards. We recommend that a geotechnical engineer be present during grading so that an adequate number of density tests may be conducted as structural fill placement occurs. In this way, the adequacy of the earthwork may be evaluated as it proceeds. RECOMMENDED SOIL COMPACTION LEVELS Location Minimum Percent Compaction* Stripped native subgrade soils, prior to fill placement (upper 12 inches), except infiltration areas Firm and Unyielding Condition Footing subgrades, fill or native (upper 12 inches) 95 All fill below building floor slabs and foundations 95 Upper 2 feet of fill below floor slabs and pavements 95 Pavement fill below two feet 90 Retaining wall backfill less than 3 feet from wall 90 Retaining wall backfill more than 3 feet from wall 95 Upper two feet of utility trench backfill 95 Utility trenches below two feet 90 Landscape Areas 90 * ASTM D1557 Modified Proctor Maximum Dry Density Placing Fill on Slopes: Permanent fill placed on slopes steeper than 5H:\1V (Horizontal: Vertical) should be keyed and benched into natural soils of the underlying slope. We recommend that the base downslope key be cut into undisturbed native soil. The key slot should be at least 8 feet wide and 3 feet deep. The hillside benches cut into the native soil should be at least 4 feet in width. The face of the embankment should be compacted to the same relative compaction as the body of the fill. This may be accomplished by over -building the embankment and cutting back to the compacted core. Alternatively, the surface of the slope may be compacted as it is built, or upon completion of the embankment fill placement. Page 10 Zipper Geo Associates, LLG Proposed Renton Senior Living Project Project No. 1187.01 December 11, 2013 Construction Dewatering Groundwater was observed in all explorations completed for this project. Groundwater flow rates into excavations that extend below the groundwater table at this site will be moderate to high. Dewatering should be expected for this project for excavations that extend below the groundwater table. The appropriate type of dewatering system should be determined by the contractor based on the conditions encountered, and should be designed and maintained by the contractor. Lowering the groundwater level during dewatering operations may cause settlement of the ground surface outside of excavations. The magnitude and aerial extent of such settlement will be a function of the drawdown radius, the duration of dewatering, and the actual soil conditions encountered in the field. Contractor -designed dewatering systems should specifically address ground surface settlements as such settlements may cause damage to adjacent pavements, structures, and utilities. The quality of groundwater discharge should be in accordance with Washington State Department of Ecology Standards. Underground Utilities We recommend that utility trenching conform to all applicable federal, state, and local regulations, such as OSHA and WISHA, for open excavations. Trench excavation safety guidelines are presented in WAC Chapter 296-155 and WISH RCW Chapter 49.17. Trench Dewatering: Excavations for utilities and underground structures that extend below the groundwater table should be expected to encounter moderate to heavy groundwater seepage. Some caving of utility trench sidewalls should be anticipated in association with groundwater seepage. We recommend that any excavations within groundwater seepage zones be undertaken only when suitable dewatering equipment and temporary excavation shoring are available, or where space is available to flatten the sidewalls. Dewatering should be expected for this project if utilities will extend below the groundwater table. The appropriate type of dewatering system should be determined by the contractor based on the conditions encountered, and should be designed and maintained by the contractor. Utility Subgrade Preparation: We recommend that all utility subgrades be firm and unyielding and free of all soils that are loose, disturbed, or pumping. Such soils should be removed and replaced, if necessary. All structural fill used to replace over -excavated soils should be compacted as recommended in the Structural Fill section of this report. If utility foundation soils are soft, we recommend that they be over - excavated 12 inches and replaced with crushed rock. Structures such as manholes and catch basins which extend into soft soils should be underlain by at least 12 inches of crushed rock fill compacted to at least 90 percent of the modified Proctor maximum dry density. This granular material could consist of crushed rock, quarry spalls, or coarse crushed concrete. Alternatively, quarry spalls or pea gravel could be used until above the water level. It may be necessary Page 11 Zipper Geo Associates, LLC Proposed Renton Senior Living Project Project No. 1187.01 December 11, 2013 to place a geotextile fabric over the native subgrade soils if they are too soft, to provide a separation between the bedding and subgrade soils. Bedding: We recommend that a minimum of 4 inches of bedding material be placed above and below all utilities or in general accordance with the utility manufacturer's recommendations and local ordinances. We recommend that pipe bedding consist of Gravel Backfill for Pipe Zone Bedding as specified in Section 9-03.12(3) of the WSDOT Standard Specifications. All trenches should be wide enough to allow for compaction around the haunches of the pipe, or material such as pea gravel should be used below the spring line of the pipes to eliminate the need for mechanical compaction in this portion of the trenches. If water is encountered in the excavations, it should be removed prior to fill placement. Trench Backfill: Materials, placement and compaction of utility trench backfill should be in accordance with the recommendations presented in the Structural Fill section of this report. We recommend that the initial lift thickness not exceed one foot unless recommended by the manufacturerto protect utilities from damage by compacting equipment. Light, hand operated compaction equipment may be utilized directly above utilities if damage resulting from heavier compaction equipment is of concern. Temporary and Permanent Slopes Temporary excavation slope stability is a function of many factors, including: • The presence and abundance of groundwater; • The type and density of the various soil strata; • The depth of cut; • Surcharge loadings adjacent to the excavation; and • The length of time the excavation remains open. As the cut is deepened, or as the length of time an excavation is open, the likelihood of bankfailure increases; therefore, maintenance of safe slopes and worker safety should remain the responsibility of the contractor, who is present at the site, able to observe changes in the soil conditions, and monitor the performance of the excavation. It is exceedingly difficult underthe variable circumstances to pre -establish a safe and "maintenance -free" temporary cut slope angle. Therefore, it should be the responsibility of the contractor to maintain safe temporary slope configurations since the contractor is continuously at the job site, able to observe the nature and condition of the cut slopes, and able to monitor the subsurface materials and groundwater conditions encountered. Unsupported vertical slopes or cuts deeper than 4 feet are not recommended if worker access is necessary. The cuts should be adequately sloped, shored, or supported to prevent injury to personnel from local sloughing and spalling. The excavation should conform to applicable Federal, State, and Local regulations. Page 12 Zipper Geo Associates, LLC Proposed Renton Senior Living Project Project No. 1187.01 December 11, 2013 According to Chapter 296-155 of the Washington Administrative Code (WAC), the contractor should make a determination of excavation side slopes based on classification of soils encountered at the time of excavation. Temporary cuts may need to be constructed at flatter angles based upon the soil moisture and groundwater conditions at the time of construction. Adjustments to the slope angles should be determined by the contractor at that time. We recommend that all permanent cut or fill slopes constructed in native soils or with imported structural fill be designed at a 2H:1V (Horizontal: Vertical) inclination or flatter. If applicable, interior slopes of stormwater ponds should be inclined no steeper than 3H:1V. All permanent cut and fill slopes should be adequately protected from erosion both temporarily and permanently. If the slopes are exposed to prolonged rainfall before vegetation becomes established, the surficial soils will be prone to erosion and possible shallow sloughing. We recommend covering permanent slopes with a rolled erosion protection material, such as Jute matting or Curlex II, if vegetation has not been established by the regional wet season (typically November through May). Building Foundation Support The soils observed in our explorations extending to a depth of about 20 to 25 feet below existing site grades are not suitable for shallow foundation support without excessive differential settlement resulting from static loads as well as liquefaction -induced settlement and strength loss. Therefore, we recommend the building be supported on deep foundations. Alternatively, stone columns, Geopiers or other methods of ground improvement could be considered to improve existing soils to a condition suitable for shallow foundation support. Recommendations and further discussion for deep foundations and ground improvement are provided below. Auger Cast -in -Place Concrete Piles For deep foundations, it is our opinion that auger cast -in -place concrete piles (ACIP piles) are suitable for the project. Recommendations for ACIP pile allowable compressive and uplift capacities for various pile diameters and installation depths are provided in the attached Figure 2. The recommendations for pile capacities (compressive, uplift, and lateral) assume a minimum pile spacing of 3D where D is the diameter of the pile. The minimum embedment depth of ACIP piles should be based on the recommendations presented below for lateral pile resistance. Additional recommendations and considerations for ACIP piles are provided below. Downdrag loads: Liquefaction -induced settlement will result in down drag loads on ACIP piles for the seismic case. The downdrag loads vary from 30 to 50 kips depending on pile diameter. The seismic capacities presented on Figure 2 have been reduced to account for downdrag caused by liquefaction. Page 13 Zipper Geo Associates, LLC Proposed Renton Senior Living Project Project No. 1187.01 December 11, 2013 Lateral Resistance: Resistance to lateral loads can be developed through passive earth pressure on embedded foundation elements and lateral resistance of piles embedded in soil. Passive earth pressure on foundation elements may be calculated assuming an ultimate passive resistance of 400 pounds per cubic foot equivalent fluid pressure (triangular distribution). We recommend that passive resistance be neglected in the upper 18 inches of embedment. For allowable stress design, we recommend a minimum 1.5 safety factor be used on passive earth pressures. The table below provides recommendations for lateral pile resistance. The recommendations below assume pile heads will be "fixed" into pile caps. Pile Pile Head Minimum Embedment Point of Fixity Allowable Lateral Diameter Deflection Depth Below Existing [depth below existing Load (kips) (in) (in) Site Grade grade in feet) (ft) 16 % 40 26 8 18 % 40 29 10 24 % 50 36 16 Foundation Depth and Width: For frost protection, the bottom of all exterior footings should bear at least 18 inches below the lowest adjacent outside grade, whereas the bottoms of interior footings should bear at least 12 inches below the surrounding slab surface level. We recommend that all continuous wall and isolated column footings be at least 12 and 24 inches wide, respectively. Estimated Foundation Settlement: Estimated total settlement of foundations supported on ACIP piles as recommended in this report is approximately one inch or less. Estimated differential settlements are approximately ''/: inch or less in 40 feet. ACIP Pile Construction Considerations Auger cast piles should be installed to the recommended pile tip elevations using a continuous -flight, hollow -stem auger. As is common practice, the pile grout would be pumped under pressure through the hollow stem as the auger is withdrawn. We recommend that the auger cast piles be installed by a contractor experienced in their placement and using suitable equipment. Grout pumps must be fitted with a volume -measuring device and pressure gauge so that the volume of grout placed in each pile and the pressure head can be easily determined. While grouting, the rate of auger withdrawal must be controlled such that the volume of grout pumped is equivalent to at least 115 percent of the theoretical hole volume. However, pressure grouting techniques may result in grout volumes in excess of 115 percent of the theoretical volume because the grout may tend to flow out into the loose and soft soil zones. Based on our experience with similar projects in the Renton area, grout volumes in excess of 130 to 170 percent are not uncommon in the area. Page 14 Zipper Geo Associates, LLC Proposed Renton Senior Living Project Project No. 1187.01 December 11, 2013 A minimum grout line pressure of 100 psi must be maintained while grouting. Also, a minimum head of grout of 8 feet should be maintained above the auger tip at all times as the auger is being retracted from the hole in order to maintain borehole stability. However, higher heads should be expected based on our experience with similar projects in the Renton area. Our experience with a nearby project indicates that grout heads on the order of 15 to 20 feet were required to maintain bore hole stability. Grout heads on this project resulted in grout volumes on the order of 130 to 170 percent of the theoretical grout volume. We recommend that there be a waiting period of at least sixteen hours between installation of piles spaced closer than about 10 feet center -to -center, in order to avoid disturbance of concrete undergoing curing in a previously cast pile. Although no apparent obstructions were encountered within the recommended pile depths in Boring B- 1, obstructions, such as buried logs and stumps, may be encountered during pile installation. The use of pre -excavation or other techniques may be required to deal with obstructions and the contractor should be prepared to use these or other similar procedures where necessary. If pile refusal occurs above the recommended pile tip elevation, our firm should evaluate the allowable capacity of the short pile. It should be noted that the recommended pile tip elevations and capacities presented above are based on assumed uniformity of soil conditions across the site. There may be unexpected variations in the depth to and characteristics of the supporting soils. In addition, no direct information regarding the capacity of auger cast piles (e.g., driving resistance data) is obtained while this type of pile is being installed. Therefore, it is particularly important that the installation of auger cast piles be completed under the direct observation of an experienced geotechnical engineer. Accordingly, we recommend that pile installation be monitored by a member of our staff who will observe installation procedures and evaluate the adequacy of individual pile installations. Additionally, we recommend construction specification similar to those recommended in Geotechnical Engineering Circular NO. 8, Design and Construction of Continuous Flight Auger Piles (FHWA 2007) be used for the project. Auger cast pile construction at the project site will create saturated spoils that will tend to flow. An appropriate plan should be developed to contain and remove the spoils. Ground Improvement As an alternative to ACID pile foundation support, ground improvement could be considered. The use of ground improvement would allow the building to be supported on conventional shallow foundations. Additionally, the slab could be supported on -grade. Ground improvement is typically completed by a specialty contractor on a design build basis to meet performance criteria (allowable total and differential settlements) established by the owner or structural Page 15 Zipper Geo Associates, LLC Proposed Renton Senior Living Project Project No. 1187.01 December 11, 2013 engineer. The contractor would use the data (boring and CPT logs) in this report as the basis for the specific design, or acquire additional data if they deem necessary. Ground improvement types can generally be separated into two categories; densification and reinforcement. Methods for densification include dynamic compaction, vibro replacement stone columns, drainage and surcharge, and compaction grouting. Methods for reinforcement include vibro replacement stone columns, deep soil mixing, compaction grouting, chemical grouting, and jet grouting. The appropriate method for a specific project is a function of many parameters including gradation of the treatment soils, ground water conditions, pre-treatment soil strength, plasticity of the treatment soils, thickness/depth of treatment soils, and required performance criteria. Dynamic compaction is not feasible for this project as it would create significant ground vibrations that could damage the adjacent existing building to the north. Drainage and surcharge are not feasible for this project as surcharge cannot adequately density potentially liquefiable soils. Considering the thickness of soils to be treated for this project (roughly 20 to 30 feet), we expect that vibro replacement stone columns working to both densify potentially liquefiable soils and reinforce soft, fine-grained soils can likely meet performance requirements and will be more economical than other alternatives. However, we recommend the project team consult with local ground improvement contractors (such as Hayward Baker, Geopier, and DBM) to evaluate cost and feasibility of ground improvement options. For design of ground improvement for the project, we recommend the project team and ground improvement contractors consider the following: • Performance Criteria: We recommend the project team provide performance criteria to perspective ground improvement contractors including allowable static and seismic total and differential foundation settlements and foundation loads. • Geotechnical Information: Perspective ground improvement contractors should be provided a copy of this report. However, perspective ground improvement contractors should be provided an opportunity to acquire additional geotechnical data or request additional geotechnical data to satisfy their understanding of subsurface soil and groundwater conditions at the site from which their design and cost will be largely based. • Existing Site Conditions: Perspective ground improvement contractors should review and understand existing site conditions that may impact their work. Of particular note is existing underground utilities and an existing building located along the north property line that is located within about 20 feet of the proposed north building line. Based on our review of building plans obtained from the City of Renton, we understand the existing building is pile -supported. We recommend perspective ground improvement contractors review available information from the city of Renton concerning this existing building and potential impacts of ground improvement work on this building and its related components. Page 16 Zipper Geo Associates, LLC Proposed Renton Senior Living Project Project No. 1187.01 December 11, 2013 • Verification Testing: The selected ground improvement contractor should be required to complete some form of post -installation verification testing (such as load tests) to verify their design and design assumptions. Building On -Grade Concrete Floor Slab The following sections provide recommendations for on -grade floor slabs. Slab Support: Subsurface soil conditions are not suitable for support of the lower level building floor slab without unacceptable differential settlement. We recommend the building floor slab be supported on ACIP piles. Alternatively, if ground improvement is completed under the floor slab, the slab could be supported on grade. Recommendations for ACIP piles and ground improvement are discussed above. Subgrade Preparation: Slab subgrades should be prepared in accordance with the Site Preparation and Structural Fill sections of this report. Capillary Break: To provide a capillary break, uniform slab bearing surface, and a minimum subgrade modulus of 150 pci, we recommend the on -grade slabs be underlain by a 6-inch thick layer of compacted, well -graded granular fill contain less than 5 percent fines, based on that soil fraction passing the U.S. No. 4 sieve. Alternatively, a clean angular gravel such as No. 7 aggregate per WSDOT: 9-03.1(4) C could be used for this purpose. Alternative capillary break materials should be submitted to the geotechnical engineer for review and approval before use. Vapor Retarder: The use of a vapor retarder should be considered beneath concrete slabs on grade that will be covered with wood, tile, carpet or other moisture sensitive or impervious coverings, or when the slab will support equipment sensitive to moisture or is otherwise considered moisture -sensitive. When conditions warrant the use of a vapor retarder, the slab designer and contractor should refer to ACI 302 and/or ACI 360 for procedures and cautions regarding the use and placement of a vapor retarder. Backfilled Permanent Retaining Walls We expect the project may include backfilled, cast -in -place (c.i.p.) concrete retaining walls or other walls. For backfilled permanent foundation walls associated with the building, refer to information above for foundation support. Additional recommendations for these structures are provided below. If other, site retaining walls not associated with the building are required, we recommend we be consulted for additional recommendations regarding foundation support. Lateral Earth Pressures: The lateral soil pressures acting on backfilled retaining walls will depend on the nature and density of the soil behind the wall, and the ability of the wall to yield in response to the earth loads. Yielding walls (i.e. walls that are free to translate or rotate) that are able to displace laterally at least 0.001H, where H is the height of the wail, may be designed for active earth pressures. Non -yielding Page 17 Zipper Geo Associates, LLC Proposed Renton Senior Living Project Project No. 1187.01 December 11, 2013 walls (Le. walls that are not free to translate or rotate) should be designed for at -rest earth pressures. Non -yielding walls include walls that are braced to another wall or structure, and wall corners. Assuming that walls are backfilled and drained as described in the following paragraphs, we recommend that yielding walls supporting horizontal backfill be designed using an equivalent fluid density of 35 pcf (active earth pressure). Non -yielding walls should be designed using an equivalent fluid density of 50 pcf (at -rest earth pressure). Design of permanent retaining walls should consider additional earth pressure resulting from the design seismic event. For the seismic case, yielding walls should be designed for an additional uniform (rectangular), seismic earth pressure distribution of 7H and non -yielding walls should be designed for a uniform, seismic earth pressure distribution of 16H. The recommended seismic earth pressure distributions should be added to the above static earth pressure values. The above -recommended lateral earth pressures do not include the effects of sloping back -fill surfaces, surcharges such as traffic loads, other surface loading, or hydrostatic pressures. If such conditions exist, we should be consulted to provide revised earth pressure recommendations. Adequate drainage measures must be installed to collect and direct subsurface water away from subgrade walls. All backfilled walls should include a drainage aggregate zone extending two feet from the back of wall for the full height of the wall. The drainage aggregate should consist of material meeting the requirements of WSDOT 9-03.12(2) Gravel Backfill for Walls. A minimum 4-inch diameter, perforated PVC drain pipe should be provided at the base of backfilled walls to collect and direct subsurface water to an appropriate discharge point. Drain pipe perforations should be protected using a non -woven filter fabric such as Mirafi 140N. Wall drainage systems should be independent of other drainage systems such as roof drains. Drainage Considerations Surface Drainage: Final site grades should be sloped to carry surface water away from buildings and other drainage -sensitive areas. Additionally, site grades should be designed such that concentrated runoff on softscape surfaces is avoided. Any surface runoff directed towards softscaped slopes should be collected at the top of the slope and routed to the bottom of the slope and discharged in a manner that prevents erosion. Building Perimeter FootinjR Drains and Retainine Wall Drains: We recommend that the new buildings and retaining walls be provided with a footing drain system to reduce the risk of future moisture problems and the buildup of hydrostatic pressures. The footing drains should consist of a minimum 4-inch diameter, Schedule 40, rigid, perforated PVC pipe placed at the base of the heel of the footing with the perforations facing down. The pipe should be surrounded by a minimum of 6 inches of clean free -draining granular Page 18 Zipper Geo Associates, LLG Proposed Renton Senior Living Project Project No. 1187.01 December 11, 2013 material conforming to WSDOT Standard Specification 9-03.12(4), Gravel Backfill for Drains. Anon -woven filter fabric such as Mirafi 140N, or equivalent, should envelope the free -draining granular material. At appropriate intervals such that water backup does not occur, the drainpipe should be connected to a tightline system leading to a suitable discharge. Cleanouts should be provided for future maintenance. The footing drain system must be independent from the roof drain system. Pavements Pavement Life and Maintenance: It should be realized that asphaltic pavements are not maintenance - free. The following pavement sections represent our minimum recommendations for an average level of performance during a 20-year design life; therefore, an average level of maintenance will likely be required. A 20-year pavement life typically assumes that an overlay will be placed near the midpoint of that 20 year life span. Thicker asphalt, base, and subbase courses would offer better long-term performance, but would cost more initially. Conversely, thinner courses would be more susceptible to "alligator" cracking and other failure modes. As such, pavement design can be considered a compromise between a high initial cost and low maintenance costs versus a low initial cost and higher maintenance costs. The recommendations presented below are based on AASHTO Low -Volume Road Design methodologies as presented in the 1993 AASHTO Guide for Design of Pavement Structures. Traffic and Reliability: Our design assumes 100,000, 18-kip equivalent single axle loads over the life of the pavement along the main access roads and a 75% reliability. Soil Design Values: Pavement subgrade soils are anticipated to consist of dense to very dense Glacial Till soils or site soils placed as compacted structural fill. Our analysis assumes the pavement subgrades with a minimum California Bearing Ration (CBR) value of 15. Recommended Pavement Sections: For light duty pavements (parking stalls), we recommend 2 inches of asphalt concrete over 4 inches of crushed rock base course. For heavy duty pavements (main access roads, truck delivery routes, etc.), we recommend 3 inches of asphalt concrete over 6 inches of crushed rock base course. Materials and Construction: We recommend the following regarding asphalt pavement materials and pavement construction. Subgrade Preparation: Upper 12 inches of pavement subgrade should be prepared in accordance with the recommendations presented in the Subgrade Preparation section of this report. Asphalt Concrete: We recommend that the asphalt concrete conform to Section 9-02.1(4) for PG 58-22 or PG 64-22 Performance Graded Asphalt Binder as presented in the 2012 WSDOT Standard Specifications. We also recommend that the gradation of the asphalt aggregate conform to the Page 19 Zipper Geo Associates, LLG Proposed Renton Senior Living Project Project No. 1187.01 December 11, 2013 aggregate gradation control points for %2-inch mixes as presented in Section 9-03.8(6), HMA Proportions of Materials. • Base Course: We recommend that the crushed aggregate base course conform to Section 9- 03.9(3) of the WSDOT Standard Specifications. • Compaction: All base material should be compacted to at least 95 percent of the maximum dry density determined in accordance with ASTM: D 1557. We recommend that asphalt be compacted to a minimum of 92 percent of the Rice (theoretical maximum) density or 96 percent of Marshall (Maximum laboratory) density. CLOSURE The analysis and recommendations presented in this report are based, in part, on the explorations completed for this study. The number, location, and depth of the explorations were completed within the constraints of budget and site access so as to yield the information to formulate our recommendations. Project plans were in the preliminary stage at the time this report was prepared. We therefore recommend Zipper Geo Associates, LLC be provided an opportunity to review the final plans and specifications when they become available in order to assess that the recommendations and design considerations presented in this report have been properly interpreted and implemented into the project design. The performance of earthwork, structural fill, foundations, and pavements depend greatly on proper site preparation and construction procedures. We recommend that Zipper Geo Associates, LLC be retained to provide geotechnical engineering services during the earthwork -related construction phases of the project. If variations in subsurface conditions are observed at that time, a qualified geotechnical engineer could provide additional geotechnical recommendations to the contractor and design team in a timely manner as the project construction progresses. This report has been prepared for the exclusive use of Canddle Development, and their agents, for specific application to the project discussed and has been prepared in accordance with generally accepted geotechnical engineering practices. No warranties, express or implied, are intended or made. Site safety, excavation support, and dewatering requirements are the responsibility of others. In the event that changes in the nature, design, or location of the project as outlined in this report are planned, the conclusions and recommendations contained in this report shall not be considered valid unless Zipper Geo Associates, LLC reviews the changes and eitherverifies or modifies the conclusions of this report in writing. Page 20 it A zoo 114 U4 � 4 w by S r� I s's a I } I 6 y a 6 y T a x x' a� a' [ui rwa a� w R � o � } m w I S Es w � z w a a�. u R i 3 a � R N_ N Q tus.�•uau APPENDIX A SUBSURFACE EXPLORATION PROCEDURES & LOGS APPENDIX A SUBSURFACE EXPLORATION PROCEDURES AND LOGS Field Exploration Description Our field exploration for this project included 3 geotechnical test borings and 4 electronic cone penetrometer tests (CPT) completed between September and October, 2013. The approximate exploration locations are shown on the Site and Exploration Plan, Figure 1. Exploration locations were determined by measuring off of existing site features shown on a topographic survey provided by CG Engineers. The approximate ground surface elevation at the exploration locations was determined by interpolating from topographic information shown on the above -referenced topographic survey. The exploration locations and elevations should be considered accurate only to the degree implied by the means and methods used to define them. The vertical datum for the referenced survey is not known. Boring Procedures The borings were advanced using a drill rig operated by an independent drilling company working under subcontract to ZGA. The borings were advanced using hollow stem auger drilling methods and drilling fluids (fluid cement grout) to limit heave inside the auger. An engineering geologist or geotechnical engineer from our firm continuously observed the borings, logged the subsurface conditions encountered, and obtained representative soil samples. All samples were stored in moisture -tight containers and transported to our laboratory for further evaluation and testing. Samples were obtained by means of the Standard Penetration Test at 2.5- to 5-foot intervals throughout the drilling operation. The Standard Penetration Test (ASTM: D-1586) procedure consists of driving a standard 2-inch outside diameter steel split spoon sampler 18 inches into the soil with a 140-pound hammer free falling 30 inches. The number of blows required to drive the sampler through each 6-inch interval is recorded, and the total number of blows struck during the final 12 inches is recorded as the Standard Penetration Resistance, or "blow count" (N value), if a total of 50 blows are struck within any 6-inch interval, the driving is stopped and the blow count is recorded as 50 blows for the actual penetration distance. The resulting Standard Penetration Resistance values indicate the relative density of granular soils and the relative consistency of cohesive soils. The enclosed boring logs describe the vertical sequence of soils and materials encountered in each boring, based primarily upon our field classifications. Where a soil contact was observed to be gradational, our logs indicate the average contact depth. Where a soil type changed between sample intervals, we inferred the contact depth. Our logs also graphically indicate the blow count, sample type, sample number, and approximate depth of each soil sample obtained from the boring. If groundwater was encountered in a borehole, the approximate groundwater depth, and date of observation, are depicted on the log. CPT Procedures The CPT explorations were advanced with an electric cone penetrometer, using a truck -mounted probe rig operated by an independent firm working under subcontract to ZGA. Due to the presence of gravelly fill soils mantling the site, each probe location was predrilled to variable depths. An engineering geologist from our firm continuously observed the probes while electronic monitoring equipment in the probe rig automatically logged the subsurface conditions. After each probe was completed, the probehole was backfilled with a bentonite and water grout. Throughout the probing operation, soil and groundwater properties were measured at 5-centimeter depth intervals by means of the Cone Penetration Test (CPT) as perASTM: D-3441. This testing procedure involves pushing a standard 1.5-inch diameter steel cone penetrometer into the soil with hydraulic rams. A cone penetrometer consists of a conical tip, a cylindrical sleeve, and a pressure transducer. As the penetrometer is pushed downward, the tip resistance, sleeve friction, and porewater pressure are measured electronically and plotted as a function of depth. The enclosed CPT logs present vertical plots of measured tip resistance, sleeve friction, porewater pressure and other parameters related and correlated to tip resistance, sleeve friction and porewater pressure. SCPT Procedures A Seismic Cone Penetration test (SCPT) was completed at the CPT-3 location. The SCPT consists of measuring the travel times of body waves propagating between a wave source and the ground surface and an array of geophones in an in -situ seismic cone penetrometer. These body waves comprise shear waves (S-waves) and compressional or primary pressure waves (P-waves). Seismic waves generated on the surface are detected downhole by three geophones mounted inside the penetrometer. The cone penetration test is briefly paused to conduct seismic tests at specific depths. Individual seismic tests include the recording of two opposing shear S-waves and one compression P- wave. Each seismic test is graphically compiled to create a profile of shear wave velocity with depth. Boring Location: See Figure 1, Site and Exploration Plan Drilling Company: Geologic Drill Bore Hole Dia.: 6" Too Elevation: Approximately 26.5 FT Drilling Method: HAS Hammer Tyoe: Auto B-1 Date Drilled: 9111/2013 Drill Rig: Track Lagged by: RAR SOIL DESCRIPTION PENETRATION RESISTANCE (blows/foot)Lu y v� i: ALStandard Penetration Test c' L The stratification lines represent the approximate boundaries Z (I Hammer 3 4 Hammer Weight and Drop: 0 4) between soil types. The transition may be gradual. Refer to E 3 report text and appendices for additional information. o m ~ 0 0 20 40 60 8 inches Crushed Rock------------ -------------� Loose, moist, brown, gravelly SAND (fill) Very loose, moist, orange -brown, fine SAND with trace silt I i I S-1 112" 4 _ 5 Very soft, saturated, orange -gray, sandy SILT S-2 12 A 2 ------------------------------------------- Very loose, saturated, gray -brown, silty fine SAND S-3 18" — -- - -1 -- --i-i 2 i -------------------------------------------- ..+.�.•. 10 Very soft, saturated, gray, sandy SILT I � I 5-4 � t2" � li 1 I 15------------------------------------------- Very soft, saturated, gray, sandy SILT with thin layers of silty fine $AND ss 1a" 1 I I i II I T - i 20 I Loose tomediumdense, saturated, gray, medium to coarse _ GRAVEL with some sand P25 SAMPLE LEGEND GROUNDWATER LEGEND O % Fines (c0.075 mm) I2-inch O.D. split spoon sample 0 Clean Sand O % Water (Moisture) Content 3-inch I.D. Shelby tube sample ® Benlonite Plastic Limit Liquid Limit Grout/Concrete Natural Water Content ® Screened Casing Renton Senior Living TESTING KEY ❑ Blank Casing 325 Rainer Ave. South GSA = Grain Size Analysis S Groundwater level at Renton, WA time of drilling (ATD) or 20OW = 200 Wash Analysis ?_ on date of Date: October, 2013 Project No.: 1187.01 Consol. = Consolidation Test measurement. Zipper Geo Associates BORING g-� Att. = Atterberg Limits 19023 36th Ave. W, Suite D LOG; Lynnwood, WA Page 1 of 3 Boring Location: See Figure 1, Site and Exploration Plan Drilling Company: Geologic Drill Bore Hole Dia.:6" Too Elevation: Approximately 26.5 FT Drilling Method: HAS Hammer Tyne: Auto B-1 Date Drilled: 9/1112013 Drill Rig: Track Logaed bv: RAR SOIL DESCRIPTION PENETRATION RESISTANCE (blowsttoot) E w A Standard Penetration Test The stratification lines represent the approximate boundaries z EL' — m between soli types. The transition may be gradual. Refer to Hammer Weight and Drop: 3 Q F- report text and appendices for additional information, o g C9 0 20 40 60 m 25 Medium dense, saturated, gray, medium to coarse GRAVEL sa s _ __.I,._ _ ;21 with some sand } �.. I I 30 5-8 12" _ 20 II I i grades to dense and sandy 50 ' SAMPLELEGEND GRQWNDWATERLE END I2-inch O.D. split spoon sample ❑ Clean Sand 3-inch I.D. Shelby tube sample ® Bentonite Grout/Concrete ® Screened Casing TE TIC NG KEY ❑ Blank Casing GSA = Grain Size Analysis Groundwater level at time of drilling (ATD) or 200W = 200 Wash Analysis on date of Consol. = Consolidation Test ti measurement. Att. = Atterberg Limits T I I t I29 I ' 48 I I I L_! % Fines (<0.075 mm) O % Water (Moisture) Content Plastic Limit i® d Liquid Limit Natural Water Content Renton Senior Living 325 Rainer Ave. South Renton, WA Date: October, 2013 Project No.: 1187.01 Zipper Geo Associates BORING g_,� 19023 36th Ave. W. Suite D LOG: Lynnwood, WA Page 2 of 3 Boring Location: See Figure 1, Site and Exploration Plan Drilling Company: Geologic Drill Bore Hole Dia.! 6" Too Elevation: Approximately 26.5 FT Drilling Method: HAS Hammer Type: Auto B-1 Date Drilled: 911112013 Drill Rig: Track Logged by. RAR SOIL DESCRIPTION PENETRATION RESISTANCE (blows/foot) _ U) s (n A Standard Penetration Test Y oL The stratification lines represent the approximate boundaries J m z a 2 m L Hammer Weight and Drop: m between soil types. The transition maybe gradual. Referto £ ar ~ report text and appendices for additional information. u, U) ° m 0 0 20 40 60 50 Dense, saturated, medium to coarse GRAVEL with some sand 5-12 all ! 47 Boring completed at 51.5 feet on 9-11-13. Groundwater measured at 6.2 feel on 1011 Oil 3. ! ! 1,70 75 ' SAMPLE LEGEND GRQUNDWATER LEGEND I2-inch O.D. split spoon sample ❑ Clean Sand 3-inch I.D. Shelby tube sample Bentonite Grouticoncrete Screened Casing TESTING KEY ❑ Blank Casing GSA = Grain Size Analysis V Groundwater level at time of drilling (ATD) or 20OW = 200 Wash Analysis ?_ on dale of Consoi. = Consolidation Test N measurement. Att. = Atterberg Limits !jjII �Li I J. I _ I t� f O % Fines (i0.075 mm) a % Water (Moisture) Content Plastic Limit i e d Liquid Limit Natural Water Content Renton Senior Living 325 Rainer Ave. South Renton, WA Date: October, 2013 Project No.: 1187.01 Zipper Geo Associates BORING B-1 19023 36th Ave. W, Suite D LOG: Lynnwood, WA Page 3 of 3 1 Boring Location: See Figure 1, Site and Exploration Plan Drilling om art : Geologic Drill Bore Hole Dia.:6" Ton Elevation: 28 FT Drilling Method: Hollow Stem Auger Hammer Tvoe: Cat Head B_2 Date Drilled: 101212013 DrillBig-Deep Rock XL Loaned bv: JPC SOIL DESCRIPTION PENETRATION RESISTANCE (blowsrfoot) iRlE nV) w A Standard Penetration Test � E a The stratification lines represent the approximate boundaries z a d v c A Hammer Weight and Drop: �j w between soil types. The transition may be gradual. Refer to E Q report text and appendices for additional information. N o C7 0 20 40 $4 0 3.5 inches Asphalt concrete pavement over 8 inches crushed L i ravel----------------------------------- `i Veryi1 loose, wet, gray -brown, silt SAND with trace ravel 9 Y Y 9 i 51 4" -- 3 ------------------------------------------- 5 Soft, wet to saturated, gray, sandy SILT with trace peaty organics sz 12, ---------------------------- ---- Very loose, saturated, gray SAND with trace silt ----------- sa �r' i 1U grades to medium dense S4 I 12" 1 jl�� Boring completed at 11.5 feet on 1012113. Groundwater measured at 6.5 feet on 10/10113. M ! F15-I SAMPLELEGEND GRQUNDWATERLEGEND I2-inch O.D. split spoon sample ❑ Clean Sand 3-inch I.D. Shelby tube sample Bentonite Grout/Concrete Screened Casing TESTING KEY ❑ Blank Casing GSA = Grain Size Analysis 7 Groundwater level at time of drilling (ATD) or 200W = 200 Wash Analysis ? on date of Consol. = Consolidation Test measurement. Att. = Atterberg Limits 4 4 I O % Fines (<0.075 mm) O % Water (Moisture) Content Plastic Limit Liquid Limit Natural Water Content Renton Senior Living 325 Rainer Ave. South Renton, WA Date: - Project No.: 11137.01 Zipper Geo Associates BORING B-2 19023 36th Ave. W, Suite D LOG; Lynnwood, WA Page 1 of 1 Boring Location: See Figure 1, Site and Exploration Plan Drilling Comoanv: Geologic Drill Bore H_ ole Dia.: 6" Top Elevation: 28 Drilling Method: Hollow Stem Auger Hammer Tvpe: Cat Head B-3 Date Drilled: 101212013 Drill Rig: Deep Rock XL Logged bv: JPC SOIL DESCRIPTION PENETRATION RESISTANCE (blowstfoot) LLJ oCn L Standard Penetration Test L a The stratification lines represent the approximate boundaries Z a > v 2 E A Hammer Weight and Drop: U �, ar between soil types. The transition maybe gradual. Referto E 3 ~ report text and appendices for additional information. o 0 0 20 40 60 0 4 inches Asphalt concrete pavement over 8 inches crushed j _,gravel - P . Ve loose, wet, gray, silty SANDsi i I ------------------------------------------- Soft, wet to saturated, gray brown, sandy SILT with some '' = ,i 5 peaty organics III: - -� - -- _----------------------------------------- looesaturated,gray,SAND with trace silt S3 12" 4VerY 10 Medium dense, saturated, gray, gravelly SAND T S4 I 12" _'-..t♦ i - 1-L._ 17 Boring completed at 11.5 feet on 1012113. Groundwater measured at 6.6 feet on 10/10113. .....-- - — i i li --r - — 4..� - - t204 25 ' SAMPLE LE END GROUNDWATER LEGEND I2-inch Q.D. split spoon sample ❑ Clean Sand 3-inch I.D. Shelby tube sample ® Bentonite Grout/Concrete Screened Casing TESTING KEY ❑ Blank Casing GSA = Grain Size Analysis V Groundwater level at time of drilling (ATD) or 200W = 200 Wash Analysis ? on date of Consol. = Consolidation Test N measurement. Aft. = Atterberg Limits -I 17 Ili I I <> °% Fines (<0.075 mm) O % Water (Moisture) Content Plastic Limit Liquid Limit Natural Water Content Renton Senior Living 325 Rainier Ave. South Renton, WA Date: - Project No.: 1187.01 Zipper Geo Associates BORING B-3 19023 36th Ave. W, Suite D LOG: Lynnwood, WA Page 1 of 1 Depth (ft) 10 15 20 25 30 - ubsurFace Technolog Operator: SAM CPT DatefTime: 101312013 11:14:42 AM Sounding: CPT-1 Location: RESERVE AT RENTON Cone Used: OSG0457 Job Number: 1187.01 Tip Resistance Qt TSF 0 I I I I I I I I I � I I I I Local Friction Fs TSF 250 0 5 Friction Ratio Pore Pressure Diff PP Ratio Soil Behavior Type' FSIQt (%) Pw PSI (Pw-Ph)/Qt (%) Zone: USC-1983 0 10 -20 100 -20 100 0 12 �I I III I II I I�.�II IIII I I , --1 T- , I_T -f" T T...I fIl1._ it I ii • � �I I I I 1 I I I I I III I II I I i I i ill I I II I I I I I 1 1 1-1 1.1 I I IIIII I � IIl11111.1�11 Maximum Depth = 2516 feet ■ 1 sensitive fine grained ■ 4 silty clay to clay ■ 2 organic material ■ 5 clayey silt to silty clay ■ 3 clay ■ 6 sandy silt to clayey silt 'Soil behavior type and SPT based on data from UBC-1983 , 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 Depth I ncrement = 0.328 feel ■ 7 silty sand to sandy silt ■ 8 sand to silty sand ■ ■ 9 sand ■ li IIIIIIII I I IIII I IIIII I II ',III I I IIII I II I 10 gravelly sand to sand 11 very stiff fine grained (") 12 sand to clayey sand ( ) Depth (ft) ubsurface Technolog ; Operator: SAM CPT DaterTime: 101312013 11:48:34 AM Sounding: CPT-2 Location: RESERVE AT RENTON Cane Used: DSG0457 Jab Number: 1187.01 Local Friction Friction Raba Pore Pressure Diff PP Ratio Soil Behavior Type' Fs TSF Fs1Qt (°%) Pw PSI (Pw-Ph)/Qt (%) zone: UBC-1983 250 0 5 0 10 -20 100 -60 100 0 12 I I � IIII ILL I I I I I I IIIIII I II�II I IIIIII I I� I I I i I - I I I I I I 1 I III I .I I I I I I � III I I- I I� 1111 11 1 � I I I IIIIIIIII IIIII I I I I I Ii II I I I I I I I I II I I �I �Il;lli I I 11� �i 11 II II II i �'I I I I I I I I I III I I I I' I r;�3 �•T � 3; I I I i 1 I I I l k /_k I L-Ili I I i i I I I I I I I I I I I I I I Maximum Depth = 24.93 feet Depth Increment = 0.328 feet p P ■ 1 sensitive fine grained ■ 4 silty clay to clay ■ 7 silty sand to sandy silt ■ 10 gravelly sand to sand ■ 2 organic material ■ 5 clayey silt to silty clay 8 sand to silty sand ■ 11 very stiff fine grained ('} ■ 3 clay ■ 6 sandy silt to clayey silt ■ 9 sand ■ 12 sand to clayey sand ('} 'Soil behavior type and SP7 based on data from UBC-1983 Tip Resistance QtTSF 0 0 I� 5 10 j ubsurface Technolog Operator: SAM CPT Date/Time: 10/312013 10:18:23 AM Sounding: CPT-3 Location: RESERVE AT RENTON Cone Used: DSG0457 Job Number: 1187.01 Tip Resistance Qt TSF 0 4 5 10 Local Friction Fs TSF 250 0 5 Depth 15 - 20 25 Friction Ratio FslQt (%) 0 1 i Maximum Depth = 24.93 feet ■ 1 sensitive fine grained ■ 4 silty clay to day ■ 2 organic material ■ 5 clayey silt to silty clay ■ 3 clay ■ 6 sandy silt to clayey silt 'Soil behavior type and SPT based on data from UBC-1983 Pore Pressure Diff PP Ratio Pw PSI (Pw-Ph)IQt (%) J -20 100 -20 100 — ..i_F1 T i Soil Behavior Type' Zone: UBC-1983 0 12 IF r,T I I 1 �I I ll -- -------- III LI. 7.11i i i i IIIFf{II i i IL31_I Li II ii Depth Increment = 0.328 feet ■ 7 silty sand to sandy silt ■ 10 gravelly sand to sand 8 sand to silty sand ■ 11 very stiff fine grained {`) ■ 9 sand ■ 12 sand to clayey sand (`) Depth (ft) �- ubsurface Technolog a Operator: SAM CPT DatefTime: 1002013 10:1a:23 AM Sounding: CPT-3 location: RESERVE AT RENTON Cone Used: DSG0457 Job Number: 1187.01 5 10 15 20 25 Tip Resistance Soil Behavior Type* Qt TSF Zone: UBC-1983 0 400 0 12 i I i I Ii II I I i I I �, II II I I I I I I I I I I I I I l I I I I I I I I I I I I 1 I I I I 11 1 1 1 1 1 1� I Maximum Depth = 24.93 feet ® 1 sensitive fine grained ■ 4 silty clay to day ■ 2 organic material ■ 5 clayey silt to silty clay ■ 3 day ■ 6 sandy silt to clayey silt *Soil behavior type and SPT based on data from UBC-1983 Seismic Delay (milliseconds) 0 60 i II i19.02 I I I I i I II ' 3324 • I I I I I I I I I 41 i29 Seismic Velocity (tt/s) 0 900 T ! I rT.I `371-g816 I i I I I I I 399.54071 b-16 47EW I � I I I I illll 459.9981 I I I I I I � L 1 1 I I I I I l l I I I I I I I I I I I I 6312 Depth Increment = 0.328 feet ■ 7 silty sand to sandy silt ■ 10 gravelly sand to sand 8 sand to silty sand ■ 11 very stiff fine grained (*} ■ 9 sand ■ 12 sand to clayey sand (*} YI ubsurface Technolog Operator; SAM CPT Datefrime: 101312013 12:40:42 PM Sounding: CPT-4 Location: RESERVE AT RENTON Cone Used: DSG0457 Job Number: 1187.01 Tip Resistance Qt TSF 0 0 T- 5 110 Depth 15 A 20 25 30 Local Friction Friction Ratio Pore Pressure Diff PP Ratio Soil Behavior Type" Fs TSF Fs1Qt (%) Pw PSI (Pw-Ph)/Qt (%) Zone: UBC-1983 250 0 5 0 10 -20 100 -20 100 0 12 I I I I I I II I I I I I I i I II II I; I�;I�;II I II;L;I� I I I I I I IIII; I 1 I IIII; ; I I I I I I I I I II I; I i II I I I I I I I I I I I I I l i I I I ! I I I III I 1 I I I�I I 1 I . Maximum Depth = 28.54 feel ■ 1 sensitive fine grained ■ 4 silty clay to clay ■ 2 organic material ■ 5 clayey silt to silty clay ■ 3 clay ■ B sandy silt to clayey silt 'Soil behavior type and SPT based on data from UBC-1983 I 1 iihTi�l� i � i IIII IIII I I i i I r..l .i i'i9r i l l I I hil'ur..t. 1_I I III l II ;II II I � I;I II I I I lirFl�iii II I II ;II:II;II. ; I I ;II;II;II;II;� I I I ; iiEirrElaili I I I I I - i MIT Y-11 T]-i I I I � IE.f I'II IIII I I I I I I I I I Depth Increment = 0.328 feet ■ 7 silty sand to sandy silt ■ 10 gravelly sand to sand 8 sand to silty sand ■ 11 very stiff fine grained (') ■ 9 sand ■ 12 sand to clayey sand (`) ! 6�k '1 APPENDIX B LABORATORY TESTING PROCEDURES & RESULTS 1 ►_19:11010I►14:i LABORATORY TESTING PROCEDURES AND RESULTS A series of laboratory tests were performed by ZGA during the course of this study to evaluate the index and geotechnical engineering properties of the subsurface soils. Descriptions of the types of tests performed are given below. Visual Classification Samples recovered from the exploration locations were visually classified in the field during the exploration program. Representative portions of the samples were carefully packaged in moisture tight containers and transported to our laboratory where the field classifications were verified or modified as required. Visual classification was generally done in accordance with ASTM D2488. Visual soil classification includes evaluation of color, relative moisture content, soil type based upon grain size, and accessory soil types included in the sample. Soil classifications are presented on the exploration logs in Appendix A. Moisture Content Determinations Moisture content determinations were performed on representative samples obtained from the explorations in order to aid in identification and correlation of soil types. The determinations were made in general accordance with the test procedures described in ASTM D 2216. Moisture contents are presented on the exploration logs in Appendix A. Technical Information Report FOR Renton Center Senior Living 625 Renton Center Way Renton, WA GuI�t �IgVALWA CG Engineering Project No. 13133.20 December 2013 c -w � ENGINEERING 250 4th Avenue 5, Suite 200 Edmonds, WA 98020 (425) 778-8500 Table of Contents TIR Section 1: Project Overview TIR Section 2: Conditions and Requirements Summary TIR Section 3: Offsite Analysis TIR Section 4: Flow Control and Water Quality Facility Analysis and Design TIR Section S: Conveyance Analysis and Design TIR Section 6: Special Reports and Summaries TIR Section 7: Other Permits TIR Section S: CSWPPP Analysis and Design TIR Section 9: Bond Quantities, Facility Summaries, and Declaration of Covenant TIR Section 10: Operations and Maintenance Manual C ENGINEERING TIR SECTION 1: PROJECT OVERVIEW The proposed project is a 3.67 acre site located at 625 Renton Center Way in Renton, WA. The scope of the work includes the construction of a 219-unit senior apartment building, along with its associated parking, driveways, courtyards, and utilities. The codes referenced in the design of this project were the 2009 King County Surface Water Design Manual and the 2009 City of Renton Amendments to the king County Surface Water Design Manual, henceforth referred to in this report as SWDM and CORA, respectively. Predeveloped Condition The eastern half of the site is a parking lot which blends in with the parking for the overall Renton Center area. The drive isle on the north property line is actually shared with the adjacent Fred Meyer parking lot. The western half of the lot is also developed, but is a less used parking lot. There are several 40' long parking spaces for trucks, and a significant portion of the area is gravel rather than pavement. The existing site generally only has low slopes, ranging from 0.5°% to 2.0%. There are several catch basins scattered throughout the site that convey runoff. In the eastern parking lot the storm system ties into the Fred Meyer parking lot to the north. In the western parking lot the water is conveyed to the storm system in Hardie Ave SW. Existing landscaping on the site appears to be in good condition, with several trees planted throughout the various landscape islands and along the south property line. The site is bordered by the Fred Meyer parking lot and buildings on the north, a driveway on the east (from Rainer Ave, cars can take South 41h Place into the site and use this driveway to get to Fred Meyer), the Burlington Northern Railroad on the south, and Hardie Ave SW on the west. The existing land coverage is as follows: Pervious Areas Landscaping: 0.52 acres Total: 0.52 acres Impervious Areas Pavement (Parking, Walkways and Driveways): 2.45 acres Gravel: 0.70 acres Total: 3.15 acres Developed Condition Technical Information Report RENTON CENTER SENIOR LIVING — Project ##13133.20 C ENGINEERING The western half of the site will be cleared in order to accommodate a 219 unit senior apartment building. The majority of the eastern parking lot will remain as is. One drive isle will be replaced by a landscape and walkway island. Pervious Areas Landscaping: 0.96 acres Total: 0.96 acres Impervious Areas Pavement (Parking, Walkways, Driveways and Courtyard Patios): 1.72 acres Building includes unit patios): 0.99 acres Total: 2.72 acres The proposed project is in a peak rate flow control standard zone, meaning that the existing condition can be used in the stormwater calculations (for most sites is necessary to consider the existing condition a forested condition in the stormwater modeling). Because this site actually decreases the amount of impervious areas, the peak flow control rates are lessened, and a large detention or infiltration system is not necessary. This is summarized in greater detail in future chapters of this report. Most of the impervious area on the site is replaced impervious area (existing impervious areas that are re-established as impervious areas), although 25,334 square feet have to be considered new impervious areas. New impervious surfaces include the areas where there is an addition of a hard or compacted surface, or the addition of a more compacted surface. On this site, any impervious areas replacing landscaping or gravel were considered "new". Any impervious surfaces replacing asphalt or concrete were considered "replaced". This is an important distinction because the amount of flow control BMPs required to be applied per SWDM Section 5.2.1.2 is based off of those areas considered new impervious. This is further discussed in Section 4 of this report. There appears to be little to no upstream runoff conveying to the site, as it is a developed parking lot with a functioning storm drainage system. Downstream impacts are expected to be minimal, as the site will add flow control BMPs and reduce impervious areas by nearly half an acre. List of Figures 1- TIR Worksheet 2 - Site Location & Aerial Photograph Map 3 —Site Drainage, Drainage Basins, Sub -basins, and Site Characteristics (2 pages) 4—Soils Technical Information Report RENTON CENTER SENIOR LIVING —Project #13133.20 FIGURE 1: TECHNICAL INFORMATION REPORT (TIR) WORKSHEET Part 1 PROJECT OWNER AND PROJECT ENGINEER Project Owner Vintage Canddle Phone 949 715-7099 Address 3424 Via Oporto, Suite 201 Newport Beach, CA 92663 Project Engineer Greg Guillen, PE, SE Company CG Engineering Phone 425 778-8500 Part 3 TYPE OF PERMIT APPLICATION O Land Use Services Subdivision / Short Subd. / UPD 0 Buildin Services M/ CommercPin SFR El Clearin g 0 Right -of -Way Use O Other ENGINEERING Part 2 PROJECT LOCATION AND DESCRIPTION Project Name Renton Center Senior Living DDES Permit # NA Location Township 23 N Range 5 E Section 18 Site Address 625 Renton Center Way Renton. WA Part 4 OTHER REVIEWS AND PERMITS O DFW HPA O Shoreline O COE 404 Management 0 DOE Dam Safety O Structural 11 FEMA Floodplain Rockery/Vault/ O COE Wetlands O ESA Section 7 O Other Part 5 PLAN AND REPORT INFORMATION Technical Inforrraitgn Report Site Improvemen n (Engr. Plans) Type of Drainage Review Full Targeted / Type (circle one): QEuIlLJAodified / (circle): Large Site Small Site Date (include revision 10/2013 Date (include revision dates): dates): Date of Final: Date of Final: Part 6 ADJUSTMENT APPROVALS Type (circle one): Standard / Comp Description: NA Date of Approval: Preapplication /experimental / Blanket /NA Technical information Report RENTON CENTER SENIOR LIVING — Project #13133.20 C C ENGINEERING Part 7 MONITORING RE UIREMENTS Monitoring Required: YES No Describe: Install Permeable Pavements Start Date: Completion Date: Part 8 SITE COMMUNITY AND DRAINAGE BASIN Community Plan: City of Renton Special District Overlays: NA Drainage Basin: Green/Duwamish River Watershed Stormwater Requirements: Peak Rate Control Standard Part 9 ONSITE AND ADJACENT SENSITIVE AREAS ❑ River/Stream ❑ Steep Slope ❑ Lake ❑ Erosion Hazard ❑ Wetlands ❑ Landslide Hazard ❑ Closed Depression ❑ Coal Mine Hazard ❑ Floodplain ❑ Seismic Hazard ❑ Other ❑ Habitat Protection O Part 10 SOILS Soil Type Till Slopes 0.5% to 2% Low Erosion Potential ® High Groundwater Table (within 5 feet) ❑ Sole Source Aquifer ❑ Other ❑ Seeps / Springs ❑ Additional Sheets Attached Technical Information Report RENTON CENTER SENIOR LIVING — Project #13133.20 C CM eNGINC-EFUNG Part 11 DRAINAGE DESIGN LIMITATIONS REFERENCE LIMITATION / SITE CONSTRAINT O Core 2 — Offsite Analysis O Sensitive / Critical Areas O SEPA 0 Other Hil?h Groundwater limits some infiltration facilities 0 Additional Sheets Attached Part 12 TIR SUMMARY SHEET (provide one TIR Summary Sheet per Threshold Discharge Area) Threshold Discharge Area: New impervious surfaces toward Hardie Way SW (name or description) Core Requirements (all 8 apply) Discharge at Natural Location Number of Natural Discharge Locations: 1 Offsite Analysis Level: 2 / 3 dated: same as report Flow Control Leve • l 2 / 3 or Exemption Number (incl. facility summary sheet) Site BMPs: Permeable Pavements Conveyance System Spill containment located at: n/a ESC Site Supervisor: TBD prior to construction Erosion and Sediment Control Contact Phone: After Hours Phone: Responsibility: f-Civ�ate Public Maintenance and Operation If Private, Maintenance Log Required: es No Financial Guarantees and Liability Provide Yes / No Type. Basic Sens. Lake / Enhanced Basic / Bog Water Quality (include facility summary sheet) Or Exemption No. Landscape Management Plan: a No Special Requirements (as applicable) Type: CDA / SDO / MDP / BP / LMP / Shared Fac None Area Specific Drainage Requirements Name: Type: Major/ Minor/ Exemption None Floodplain / Floodway Delineation 100-Year Base Flood Elevation (or range) n/a Datum: KCAS Describe: NA Flood Protection Facilities Describe land use: Senior Apartments Source Control Describe any structural controls: NA (comm. / industrial land use) Technical Information Report RENTON CENTER SENIOR LIVING — Project #13133.20 C C ENGINEERING High -use Site: Yes a Treatment BMP: NA Oil Control Maintenance Agreement: Yes / No With whom? Other Drainage Structures Describe: Stormfilter Part 13 EROSION AND SEDIMENT CONTROL REQUIREMENTS MINIMUM ESC REQUIREMENTS MINIMUM ESC REQUIREMENTS DURING CONSTRUCTION AFTER CONSTRUCTION 0 Clearing Limits B Stabilize Exposed Surfaces B Cover Measures 17 Remove & Restore Temporary ESC Facilities 0 Clean & Remove All Silt & Debris, Ensure C?1 Perimeter Protection Operation of Permanent Facilities B Flag limits of SAO & Open Space Preservation B Traffic Area Stabilization Areas 0 Sediment Retention ❑ Other B Surface Water Collection 71 Dewatering Control Ll Dust Control 0 Flow Control Part 14 STORMWATER FACILITY DESCRIPTIONS (Note: Incl Facility Summary & Sketch) Flow Control Type/Description Water Quality Type/Description ❑ Detention ❑ Infiltration ❑ Regional Facility ❑ Shared Facility a Flow Control BMPs ❑ Other ❑ Biofiltration ❑ Wetpool ❑ Media Filtration ❑ Oil Control p Spill Control ❑ Flow Control BMPs H Other Permeable Paving Filter Cartridges Technical Information Report RENTON CENTER SENIOR LIVING —Project #13133.20 Part 15 EASEMENTS/TRACTS H Drainage Easement a Covenant ❑ Native Growth Protection Covenant ❑ Tract ❑ Other enMnIEeRING Part 16 STRUCTURAL ANALYSIS ❑ Cast in Place Vault ❑ Retaining Wall ❑ Rockery >4' high ❑ Structural on Steep Slope ❑ Other Part 17 SIGNATURE OF PROFESSIONAL ENGINEER I, or a civil engineer under my supervision, have visited the site. Actual site conditions as observed were incorporated into this worksheet and the attached Technical Information Report. To the best of my knowledge the information provided here is accurate. Date Technical Information Report RENTON CENTER SENIOR LIVING — Project #13133.20 0 ENGINEERING FIGURE 2: SITE LOCATION & AERIAL PHOTOGRAPH MAP Fred Meyer Hardware Stale f� tarma[y in � r PhatmaC c_ n. k65nClaflpn Fitr140ri � �' 5F-oppmg c ' ._ Center . r.Y'. �, t•' ';I r^ � � Plum c 4'' - -ree lark PROJECT f r, y + SITE:, " lhov V0111" r{h Lnl,t !bynf a Scion 'r Aorr�'rrn'.a - i! Rentm 'y' `Yy Rentnn FSanker5 Awn-'51�� - .sr �v FlopeyPS P t i ► 1 15t C �e A rplfh!-a s NriyhCorha�>� t515a GO; R?r,tcr.VriEagr 1 ioppanq Center HoNdaVifo Se,q!!le-lzardon �•Js C_1'�-.i c iici!:: ' FIi�dGc uj _ I ira: AT.erP -an ldirfn��rbnce 5'1 . ^m Giry Site Location Technical Information Report THE RENTON CENTER SENIOR LIVING — Project #13133.20 c C�'_ -- ENGINEERING Aerial Photograph Map Technical Information Report RENTON CENTER SENIOR LIVING —Project #13133.20 C ENGINEERING FIGURE 3: SITE DRAINAGE, DRAINAGE BASINS, SUB -BASINS, AND SITE CHARACTERISTICS The proposed project is within the Green/Duwamish River Watershed. The site features are shown on the C3.1 plan, attached within this section of the report. FIGURE 4: SOILS The proposed project has been analyzed by a geotechnical engineer and a soils report is provided in Section 6 of this report. Technical Information Report RENTON CENTER SENIOR LIVING — Project 413133.20 C C= 0 eNGINEERING TIR SECTION 2: CONDITIONS AND REQUIREMENTS SUMMARY The proposed project is being submitted for a Full Drainage Review. Therefore, the following conditions are required as specified by the SWDM and CORA. Core, Requirement #1: Discharge at a Natural Location: The project is part of the Green/Duwamish River Watershed and will be conveyed in that direction via the City of Renton storm system. The site will be conveyed to Hardie Ave SW. Core Requirement #2: Offsite Analysis: Compliance with requirement is indicated in Section 3. Core Requirement #3: Flow Control: Section 4 discusses the drainage facilities implemented for this project. This site is in the Peak Rate Flow Control Standard Zone, meaning that the site must match or lessen the 2, 10, and 100 year peak flows. Core Requirement #4: Conveyance System: Section 5 of this report demonstrates the compliance with this requirement. Core Requirement #5: Erosion & Sediment Control: Section 8 indicates the erosion control facilities that are to be implemented on the site during construction, along with various source controls required by Special Requirement #4. Core Requirement #6: Maintenance & Operations: Section 10 of this report addresses the maintenance for the various facilities being implemented on this project. Core Requirement #7: Financial Guarantees & Liabilities: These items are addressed in Section 9 of this report. Core Requirement #8: Water Quality: Section 4 of this report demonstrates the compliance with this requirement. Special Requirement #1: Other Adopted Requirements: The proposed project is in the Peak Rate Flow Control Standard Area of the City of Renton. Discussion of this is in Section 4 of this report. Special Requirement #2: Flood Hazard Area Delineation & Special Requirement #3: Flood Protection Facilities: Flooding concerns do not appear to be applicable for this project. Special Requirement #4: Source Control: Source Controls are discussed in Section 6 of this report. Special Requirement #5: Oil Control: Does not appear to be applicable for this project. Technical Information Report RENTON CENTER SENIOR LIVING —Project #13133.20 C G ENGINEERING 'TIR SECTION 3: OFFSITE ANALYSIS The proposal is to route the runoff from the area of work on the site toward the storm system at Hardie Ave SW. A Level 1 Study is required for this project_ 1. Study Area Definition and Maps This portion of the offsite analysis consists of the maps showing the property area and the area studied within the site visit and the rest of the analysis. The map in this section of the report shows the area of study. Generally the downstream conveyance path is a 60" diameter pipe system (material unknown), although a few of the sections within the downstream quarter mile are 36" and 48" diameter. Roughly 4 miles downstream of the subject property, the storm system which this project will tie into outfalls into the Black River, which then runs approximately a half mile toward the Duwamish Waterway, which flows northwesterly toward Puget Sound. 2. Resource Review Drainage and water quality problems and complaints were investigated using the King County IMAP program. None were found within the range of the required downstream analysis. Using both the King County IMAP and the City of Renton COR programs, it doesn't appear that floodplains, wetlands, steep slopes, erosion problems, or water quality problems are applicable to this project. Through coordination with Rohini Nair at the City of Renton however, it was discovered that there is actually an unmapped severe flooding problem located underneath the railroad tracks bridge. The following information was sent to CG Engineering via email: The existing flooding problem on Hardie Ave SW at the BNSF railroad underpass is a Severe Roadway Flooding Problem. It occurs during storm events that are less than the 100-year storm, results in deep flooding (more than 6"), which makes the road impassible for motor vehicles and emergency access (street is closed). There are altemate routes that motorists and emergency vehicles can use so it doesn't isolate properties access and is basically a nuisance for motorists. The problem is due to insufficient downstream capacity to convey the runoff from the highly urbanized upstream basin area, of which the Renton Center Senior Living project site is located. The Renton Center Senior Living site, is small area compared to the overall basin tributary area that conveys runoff to the drainage problem location. In Technical Information Report RENTON CENTER SENIOR LIVING — Project #13133.20 4= CM ENGINEERING addition, the Surface Water Utility 6-year Capital Improvement Program includes a project to improve conveyance capacity to reduce the flooding problem at the Hardie Ave SW BNSF railroad underpass location. The first phase of the project that will install a 60-inch storm conveyance system for an outfall at Naches Ave SW to Lind Ave SW is currently is design and permitting, with construction planned for 2014. Because of the planned Surface Water Utility CiP project and the fact that requiring higher flow control design standards on the Renton Center Senior Living project to reduce runoff from the site will not have any significant reduction or solve the existing Hardie Ave SW flooding problem at the BNSF railroad underpass, the project engineer can proceed with producing their TiR drainage report following the requirements in the City adopted Surface Water Design Standards using the Peak Rate Flow Control Standard (Existing Site Conditions). The engineer should do a level 1 offsite analysis and include information about the downstream flooding project and the planned City CiP in the TIR. However, as part of the environmental review process, if there is significant public concerns about the project and the downstream drainage problem, the City reserves the right to place a condition on the project to apply a higher stormwater flow control standard to reduce the sites contribution to the existing downstream flooding problem. 3. Field Inspection The field inspection was completed on October 8, 2013. There was a medium rain and the temperature was about 50 degrees. Upstream Analysis The proposed site takes little to no sheet flow runoff from adjacent properties. There is a main that is constructed as a portion of the overall development that runs through the eastern property line of the project site, turns north in a Type 1 CB, and then continues north into the Fred Meyer parking lot. The subject property will actually add significant amounts of landscaping to the area contributing to this existing storm main. Downstream Analysis The downstream walk did not result in the discovery of any additional concerns. The area of concern mentioned in the Resource Review was looked at and appeared to be functioning properly for the mild rain that was occurring at the time. Inverts are shallow however and it does make sense that this area could be problematic. The storm system then picks up drainage conveyance from Hardie Ave SW/Edwards Street then runs westerly, north of the Toyota Scion of Renton site and an office building for the Renton School District. After it extends west of the school district building it turns southerly to SW 7`h Street. Technical Information Report RENTON CENTER SENIOR LIVING —Project#13133.20 C C ENGINEERING Once on 7th Street the 36" x 60" arched stormwater main runs for approximately a mile before turning north on Naches Ave SW, where it then runs about 500 feet before the system's outfall. The Green/Duwamish Rive►w nnwamed ary Watershed Suhwatershershed Middle Green Rivrtr Suhwawrshed \J1--Lawer — --" Green River .J� Wamnrrd 5—d.r> Subvratershed Rl— {� u+ln+RG,4 1 i4)J King County r.w.rey: Dcwrlmn A r)f Naluibl Resources and parks ni � O Siw°ry'r'' Nz ,a.Ylwr.1/a+ruwi+rrr :nm S"b anll Water and Land Resources DEvIslon n. x.., .MGSV...a M Figure 3.3.3: The Green Duwamish River Watershed Figure 3.3.2: Downstream Basin/Study Area Map Upper 1 C.-..Abler SubWAI BYthad Technical Information Report RENTON CENTER SENIOR LIVING — Project #13133.20 r ENGINEERING Figure 3.3.3: Hardie at SNSF underpass Technical Information Report RENTON CENTER SENIOR LIVING — Project #13133.20 C C Ei FZIr 16 4. Drainage System Description and Problem Description Generally the drainage system down Hardie Ave SW appears to be functioning properly, although the rain observed during the site visit was not typical of the largest stormwater events. The drainage system's severe flooding problem is summarized in the Resource Review portion of this TIR Section. This Level 1 Analysis only consists of a field inspection, without surveying downstream pipes. This can be done at future phases if the project if required and deemed necessary by the City Engineer. Overall, contributions to the existing conveyance system from the proposed site are expected to be significantly reduced. The impervious areas on the site are actually lessened by the proposed development, and much of the new hard surfaces are permeable pavers. 5. Mitigation of Existing and Potential Problems As stated in the Resource Review by the City Engineer, the downstream problem is to be mitigated by a future drainage system upgrade in Hardie Ave SW. This project is not being required to provide additional mitigation to help the downstream problem. With that being said, the project will reduce contributing impervious areas and add low impact development facilities to meet Flow Control BMP requirements. Technical Information Report RENTON CENTER SENIOR LIVING —Project #13133.20 o ENGINEERING TIR SECTION 4: FLOW CONTROL AND WATER QUALITY FACILITY ANALYSIS AND DESIGN The overall plan is to run the site's new and replaced impervious surfaces into the existing storm systems. The western half of the site, where the vast majority of the new development will occur, is routed to the storm system in Hardie Ave SW. The eastern half of the site will continue to run into the existing catch basins, and convey toward the Fred Meyer storm system, which eventually connects to Hardie Ave SW as well. Although stormwater runs to two different places, the site was modeled as one basin for comparison of the peak flows, since the whole site ultimately connects to the Hardie Ave SW conveyance system. This comparison can be broken into two sub -basins if the City requests further detail. Impervious area is being decreased throughout the site however, and peak flows will decrease and meet peak flow control standards regardless of how the comparison between existing and developed site hydrology is broken down. PART A: EXISTING SITE HYDROLOGY The area being considered is the entire site as represented in the Predeveloped Condition sub -section in Section 1 of this report. Pervious Areas Landscaping: 0.52 acres Total: 0.52 acres Impervious Areas Pavement (Parking, Walkways and Driveways): 2.45 acres Gravel: 0.70 acres Total: 3.15 acres The landscaping was modeled as an outwash grass based on the recommendations in the geotechnical study. Peak flows for the predeveloped site were as follows: 100 year 1.53 cfs 50 year 1.40 cfs 25 year 1.14 cfs 10 year 0.93 cfs 2 year 0.79 cfs KCRTS readout is provided in this section of the report. PART 6: DEVELOPED SITE HYDROLOGY The area being considered is the entire site as represented in the Developed Condition sub -section in Section 1 of this report, with some minor changes. 5881 square feet (0.135 acres) of pavement is planned to be permeable pavers, and therefore the project can be modeled with additional pervious surfaces per SWDM Table 5.2.2.A: Flow Control Technical Information Report RENTON CENTER SENIOR LIVING — Project #13133.20 4 ENGINEERING BMP Sizing Credits. Per the table, this area can be modeled as half grass and half impervious. The modification of the table (moving 0.068 acres of pavement into the landscaping category) found in the Developed Condition sub -section of TIR Section 1 is as follows: Pervious Areas Landscapinp,: ^.aa-�2-a� 1.02 acres Total: n.6�-W awe; 1.02 acres Impervious Areas Pavement: '' .�& 1.66 acres Building includes unit patios): 0.99 acres Total: 7.75 affeS 2.65 acres Peak flows (prior to detention) were as follows: 100 year 1.33 cfs 50 year 1.20 cfs 25 year 0.96 cfs 10 year 0.81 cfs 2 year 0.68 cfs PART C. PERFORMANCE STANDARDS The proposed project is located within the Peak Flow Control Standard Area, and therefore it is required that the project not exceed the 2, 10, 100 year peak flows. As can be seen from Part A and Part B above, the 2 year peak was decreased by 0.11 cfs, the 10 year storm was decreased by 0.12 cfs, and the 100 year storm was decreased by 0.20 cfs. Because this project is a large lot with high impervious surface coverage (greater than 22,000 square feet with more than 45% impervious surface) flow control BMPs must be applied per SWDM 5.2.1.3. In applying BMPs, the civil engineer is first required to evaluate full dispersion. This is not feasible on this project because there is nowhere that could be used as a threshold discharge area for the dispersal flow path. The manual then requires that one or more in a list of BMPs be applied to a practicable amount of impervious surface. For sites with over 65% coverage, as this project is, the practicable amount is defined as "10% of the site/lot or 20% of target impervious surface, whichever is less". For large lots with high impervious surface coverage, target impervious surface shall include "all new impervious surface together with any existing impervious surface added on or ofterJanuary S, 2001". Per the discussion in TIR Section 1, there is 25,334 square feet of new impervious surface. Icing County imap shows the existing condition in a 2000 Technical Information Report RENTON CENTER SENIOR LIVING —Project#13133.20 C � ENGINEERING color ariel photo, shown in Figure 4.C.2 below. It does not appear to show any pervious areas beyond what exist on the site now_ Figure 4.C.3: Flow Control Standord Map �E -_ �HlI11mEjOE.�d LJ _ Z131-ft WMIS .......................... A twid LfR mpi� -A c�Jes . .� ...rate[ A•e ' Recreation Aistncts a Hydrography Layem RIahQA 20117 Color My I] zogscourAes. Ftntae J 2002 Golx Aorta A— PX*- 1-J 149E WU A—i I 19iF A/W A.r•I Figure 4.C.2: 2000 Color Ariel Map from King County Imop program New Impervious Surface: 25,982 square feet Technical Information Report RENTON CENTER SENIOR LIVING — Project #13133.20 C ENGINEERING, Existing Impervious Surfaces added after 1/8/2001: 0 square feet Target Impervious Surface: 25,334 square feet Practicable amount of Flow Control BMPs per SWDM 5.2.1.3: 25,982 square feet x 0.20 = 5,067 square feet 5,881 square feet of permeable pavers are being added to the site, thus meeting and exceeding this requirement. PART D. FLOW CONTROL SYSTEM No flow control system beyond the permeable pavement areas will be required per the discussion in Parts A, B, and C in this TIR section. PART E. WATER QUALITY SYSTEM The site will add 0.40 acres of pollution generating impervious surfaces, well over the 5,000 square feet that triggers the requirement. The facilities will be privately owned and maintained. Pollutant removal via infiltration was not used due to recommendations in the geotechnical report. This site falls under Basic Treatment Menu. A 96" Stormfilter is provided upstream of the storm sewer connection. The Stormfilter was sized based on KCRTS runoff calculations with a 15-minute time step. A Contech CDS2015-4-C System is provided before the Stormfilter in order to pre -settle out particles that might hinder the functionality of the Stormfilter. This was done due to the special constraints on the site. During the land use permitting phase, CG Engineering will submit for a code adjustment to use this facility. Due to space constraints on site, using a biofiltration swale, filter strip, wetpond, etc is not practical for this site. The calculations and a summary sheet are included in this section. Technical Information Report RENTON CENTER SENIOR LIVING — Project #13133.20 C G ENGINEERING Figure 4.E.1: Water Treatment Volume Summary Water Quality Subbasin Total Area (sf / ac) 44601 1.02 Impervious area (sf / ac) 37099 0.85 Pollution -Generating (sf / ac) 17411 0.40 Nan -Pollution -Generating (sf / ac) 19688 0.45 Pervious Area (sf / ac) 7502 0.17 2 yr flow (cfs) 0.405 WQ Treatment Flow (cfs) 0.142 100 yr flow (cfs) 1.09 Technical Information Report RENTON CENTER SENIOR LIVING —Project #13133.20 SECTION III FIGURE 111-2. RAINFALL REGIONS AND SCALE FACTORS ST 1.1 ' ST 1.1 ST 1.0 Rainfall Regions and Regional Scale Factors � p� Incorporated Area .c�n RiverlLake Major Road ST 1.01 LA 0.8 LA 1.0 LA 0.9 LA 1.0 LA 1.2 � f3NOXO YI6X GSN NTY IONOiION LANDSBURG 119-4 W KCRTS User's Guide December 15, 1995 Version 6.00� All files will be read/written in the Vorking Directory Working Directory:C:",kc-svrdm\output KCRTS Command CREATE a new Time Series Production of Runoff Time Series Project Location Sea-Tac Computing Series : xentonpre.tsf Regional Scale Factor 1.00 Data Type Reduced Creating Hourly Time Series File loading Time Series File:C:\IBC SWDM\MC DATA\STGGGOR.rnf 8 Outwash Grass O.S2 acres _ Scaling 'fir: P Loading Time Series File:C:\KC SWDM\XC DATA\STE160R.rnf 8 Impervious 3.15 acres Adding Yr: 8 Total Area 3.67 acres Peak Discharge: 1.53 CFS at 6:00 on Jan 9 in Year 0 Storing Time Series File:rentonpre.tsf P Time Series Computed ------------------------------------------------------------------------------ XCRTS Command Enter the Analysis TOOLS Module ------------------------------ T----- Analysis Tools Command Compute PEAKS and Flow Frequencies Loading Stage/Discharge curve:rentonpre.tsf Flow Frequency Analysis "Time Series File:rentonpre.tsf ---------------------- Project Location:Sea-Tac —Annual Peak Flow bates--- -----Flow Frequency Analysis ------ FlowRate Rank Time of Peak - - Peaks - - bank Return Prob (CFS) (CPS) Period 0.780 7 2./09/01 2:00 1.S3 1 100.00 0.990 0.673 8 1/OS/02 16:00 1.14 2 2S.00 0.960 0.933 3 12/09/02 18:00 0.913 3 10.00 0.900 0.789 6 8/26/04 2:00 0.931' 4 S.00 0.800 0.931 4 10/28/04 16:00 0.818 S" 3.00 0.667 .819 S 1/19/08 16:00 0.789 6 2.00 O.S00 1.14 2 10/26/06 0:00 0.780 7 1.30 0.231 1.93 1 1/09/08 6:00 0.673 8 1.10 0.091 `omputed Peaks 1.40 S0.00 0.980 King County Runoff Time Series Program Version 6.00 All files will be read/written in the Working Directory Working Directory:C:\kc_swdm\output KCRTS Command CREATE a new Time Series Production of Runoff Time Series Project Location Sea-Tac Computing Series RentonFullDeveloped.TSF Regional Scale Factor 1.00 Data Type Reduced Creating Hourly Time Series File Loading Time Series File:C:\KC_SWDM\KC_DATA\STOG60R.rnf Outwash Grass 1.02 acres Scaling Yr: 8 Loading Time Series File:C:\KC-SVDM\KC-DATA\STEI60R.rnf Impervious 2.65 acres Adding Yr: 8 8 8 Total Area : 3.67 acres Peak Discharge: 1.33 CFS at 6:00 on Jan 9 in Year 8 Storing Time Series File:RentonFullDeveloped.TSF 8 Time Series Computed KCRTS Command Enter the Analysis TOOLS Module Analysis Tools Command Compute PEAKS and Flow Frequencies ---------------------------------- Loading Stage/Discharge curve:rentonfulldeveloped.tsf Flow Frequency Analysis Time Series File:rentonfulldeveloped.tsf Project Location:Sea-Tac Frequencies & Peaks saved to File:RentonFullDeveloped.PKS Time Series File:rentonfulldeveloped.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- -----Flow Frequency Analysis------- FlowRate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 0.675 6 2/09/01 2:00 1.33 1 100.00 0.990 0.566 8 1/05/02 16:00 0.962 2 25.00 0.960 0.812 3 2/27/03 7:00 0.812 3 10.00 0.900 0.660 7 8/26/04 2:00 0.784 4 5.00 0.800 0.784 4 10/28/04 16:00 0.690 5 3.00 0.667 0.690 5 1/18/06 16:00 0.675 6 2.00 0.500 0.962 2 10/26/06 0:00 0.660 7 1.30 0.231 1.33 1 1/09/08 6:00 0.566 8 1.10 0.091 Computed Peaks 1.20 50.00 0.980 C C -ram ENGINEERING TIR SECTION 5: CONVEYANCE SYSTEM ANALYSIS AND DESIGN The stormwater to the site is conveyed using PVC pipes, which have been sized within this section. Calculations for the conveyance design were performed using the Rational Method for the 25- Year, 24-Hour Storm 12" inch diameter pipes convey the stormwater on site to the storm sewer. The lowest condition is a pipe with a 0.5% slope, but generally the pipes will have a greater slope. Given these conservative conditions, the pipes still convey the 25 year storm adequately. See the following pages of this report for calculations. Technical Information Report RENTON CENTER SENIOR LIVING —Project #13133.20 4= a 4 ENGINEERING Conveyance Calculations Technical Information Report RENTON CENTER SENIOR LIVING — Project #13133.20 Rational Method - Developed Conditions for: Reserve at Renton n= 0.013 Rational Method By Jared ne`e 11/14/2013 ENGINEERING Developed Conditions Chkd nave 250 4th Ave. South Scale N.T.S. sheet No. Suite 200 Job No. Edmonds, WA 98020 Reserve at Renton 13008,20 Conveyance Capacity 4-inch 6-inch 8-inch 10-inch 12-inch Slope (ftlft) 0.005 0.13 0.40 0.87 1.55 2.52 0.010 0.19 0.56 1.23 2.20 3.57 0.015 0.23 0.69 1.50 2.69 4.37 0.020 Q27 0.79 1.74 3.11 5.05 0.025 0.30 0.89 1.94 3.47 5.65 0.030 0.33 0.97 2.13 3.81 6,18 0.035 0.36 1.05 2.30 4.11 6.68 0.040 0.38 1.12 2.46 4.39 7.14 OA4S 0.40 1.19 2.60 4.66 7.57 0.050 0.43 1.26 2.75 4.91 7.98 0.055 0.45 1.32 2.88 5.15 8.37 0.060 0.47 1.38 3.01 5.38 8.75 0.065 0.49 1.43 3.13 5.60 9.10 0.070 0.50 1.49 3.25 5.81 9.45 0.075 0.52 1.54 3.36 6.02 9.78 0.080 0.54 1.59 3.47 6.21 10.10 0.085 0.56 1.64 3_58 6.40 10.41 0.090 0.57 1.68 3.68 6.59 10.71 0.095 0.59 1.73 3.78 6.77 11,01 0.100 0.60 1.78 3.88 6.95 11.29 Rational Method - Developed Conditions for: Reserve at Renton Conveyance Pipe, Subbasin 1 Q = C"g1A Te = 6.00 (assumed, since all pipe flow) Area (ac) C Dense Forest 0.10 CAVg= Eli':€E€ <E€EQ Light Forest 0 .15 Rational Method - Developed Conditions for: Reserve at Renton Conveyance Pipe, Subbasin 2 Q = Ca'giA Tc = 6.QQ (assumed, since all pipe flow) Dense Forest Light Forest Pasture Lawns Grave] Pavement & Roofs Open Water Other Area fact C 1 1 4 4 1 1 :1 44 1 1 Total Area (A) =acres C$vg= i = (Pr)(ir) Pr-- total precipitation at the project site for 24-hr duration storm ir= unit peak rainfall intensity factor ir= (ar)(Tc)^(-br) ar, br= coefficients from Table 3.2.1.13 of KCSWDM T MI ��_ r . (ir)zs= m € i25= �.. (i0200 .._.... € €.... < i'00= - � €: •`.:. Quo= C Rational Method by JE, uate 10/21/2013 ENGi1NEERING Developed Conditions cnxa Date 250 4th Ave. South Scale N.T.S. sheet No. Suite 200 Job No. Edmonds, WA 98020 Reserve at Everett13113.20 c � ENGINEERING TIR SECTION G: SPECIAL REPORTS AND STUDIES The following geotechnical report was in our analysis of the site and is included in the following pages of this report. Geotechnical Feasibility Study for Proposed Renton Center Senior Living Project by Zipper Geo Associates, LLC dated September 20, 2013 Technical Information Report RENTON CENTER SENIOR LIVING —Project#13133.20 GEOTECHNICAL ENGINEERING REPORT PROPOSED RESERVE AT RENTON PROJECT 325 RAINER AVENUE SOUTH RENTON, WASHINGTON Project No. 1187.01 October 18, 2013 Prepared for: Canddle Development Prepared by: ZGA Zipper Geo Associates, LLC Geotechnical and Environmental Consultants 19023 36t" Avenue W., Suite D Lynnwood, WA 9803 Zipper Geo Associates, LLC Geotechnical and Environmental Consulting Project No. 1187.01 October 18, 2013 Canddle Development 3424 Via Oporto, Suite 201 Newport Beach, CA 92663 Attention: Mr. Christopher Santoro Subject: Geotechnical Feasibility Study Proposed Reserve at Renton Project 325 Rainer Avenue South Renton, Washington Dear Mr. Santoro: In accordance with your request and written a AN"'. 'lion, Zipper Geo Associates, LLC (ZGA) has completed the subsurface explorations and ged -1j ie'engineering evaluation for the proposed Reserve at Renton project located at 325 R presents the findings of the subsurface expror. Our work was completed in general a"Md"%ti 2013. Written authorization to proceedgrx opportunity to be of service to you on this prod we may be of further service, please contact us. Sincerely, Zipper Geo Associates, LLC Robert A. Ross, P.E. Principal Copies: Addressee (1) CG Engineering — Chevy Chase (1) inr Nonue South in Renton, Washington. This report t6rraiid geotechnical recommendations for the project. c41 ith our proposal (Proposal No. P13215) dated July 31, provided by you on August 16, 2013. We appreciate the ect. if you have any questions concerning this report, or if John E. Zipper, P.E. Managing Principal 19023 361 Avenue west, Suite D Lynnwood, WA 98036 (425) 582-9928 TABLE OF CONTENTS Page INTRODUCTION.. ....... ....... ......................................................................................................................... 1 PROJECTUNDERSTANDING....................................................................................................................1 SURFACECONDITIONS.............................................................................................................................1 SUBSURFACE CONDITIONS...................................................................................................................... 2 RegionalGeology.............................................................................................................................................2 SoilConditions.................................................................................................................................................2 GroundwaterConditions....... ......... . ... ..... ' ............ .................. ..................... ................................... 3 Summary of Laboratory Testing......................................................................................................................4 CONCLUSIONS AND RECOMMENDATIONS............................................................................................4 General..........................................................................................................................................................4 Seismic Design Considerations........................................................................................................................4 SitePreparation.................................................................................................................... 7 Structural Fill Materials and Preparation........................................................................................................8 ConstructionDewatering..............................................................................................................................11 UndergroundUtilities........ ..... ........ ...... ............................................................................. .................... 11 Temporary and Permanent Slopes................................................................................................................12 Building Foundation Support .....................................................................................................................13 N7 Auger Cast -in -Place Concrete Piles...............................................................13 ACIP Pile Construction Considerations......,::.................................................................................14 Ground lmprovement . Building On -Grade Concrete floor Slab .............: '' 17 Backfilled Permanent Retaining Walls .... ..... .......17 Drainage Considerations ..................... .....::z..........,..................................,..,......,................................18 .`......._.. ................................................................19 .. Pavements ........� FIGURES Figure 1— Site and Exploration Plan Figure 2 — ACIP Pile Capacities APPENDICES Appendix A — Subsurface Exploration Procedures and Logs Appendix B — Laboratory Testing Procedures and Results Cover Photo Credit: Google Earth GEOTECHNICAL ENGINEERING REPORT PROPOSED RESERVE AT RENTON PROJECT 325 RAINER AVENUE SOUTH RENTON, WASHINGTON Project No.1187.01 October 18, 2013 11►1111:To]01ily111M 0 1 This report documents the surface and subsurface conditions encountered at the site and our geotechnical engineering recommendations for the proposed Reserve at Renton project located at 325 Rainer Avenue South in Renton, Washington. The project description, site conditions, and our geotechnical conclusions and design recommendations are presented in the text of this report. Supporting data including detailed exploration logs and field exploration procedures, results of laboratory testing and other supporting information are presented as appendices. Our geotechnical engineering scope of services for the,project included a literature review, site �_ reconnaissance, subsurface exploration, laboratory tpsting�=eotechnical engineering analysis, and preparation of this report. The subsurface evaluation r'nsisted of completing three geotechnical test borings and four electronic cone penetrometer (CPttt PROJECT UNDERSTANDING We understand the project will consistepf constructing a five story mixed use building and associated site improvements on a 3.67 acre property located at 325 Rainer Avenue South in Renton, Washington. The lower floor of the proposed building will include about 34,000 square feet of senior apartment space and about 5,430 square feet of commercial space. The remaining floors will include about 31,000 to 36,000 square feet of senior apartment space. Areas surrounding the site are currently developed and relatively flat. As a result, we expect finished floor elevation for the new building will be within about a foot of existing site grades. We also expect mass grading for the project to be relatively minimal with cuts and fills of 2 feet or less. We understand that detention of stormwater runoff from the site will not be required as there is existing infrastructure in place. However, we expect new stormwater collection systems as well as other underground utilities will be constructed as part of the project. The project will also include new asphalt pavements. SURFACE CONDITIONS The project site consists of a 3.67 acre property located at 325 Rainer Avenue South in Renton, Washington. The site is bordered to the north by developed commercial property; to the south by BNSF rail road right-of-way; to the east by developed commercial property; and to the west by Hardie Avenue Southwest. The project site is generally level with areas of gravel surfacing and areas of paved surfacing. Page 1 Zipper Geo Associates, LLC Proposed Reserve at Renton Project Project No. 1187.01 October 18, 2013 There are existing, abandoned and active underground utilities at the project site. Additionally, there are high tension power transmission lines that cross the east portion of the site from north to south. The project site is illustrated on the attached Figure 1, Site and Exploration Plan. SUBSURFACE CONDITIONS Regional Geology We assessed the geologic setting of the site and the surrounding vicinity by reviewing information published on the Washington State Department of Natural Resources' (DNR) Subsurface Geology Information System website (https://fortress.wa.gov/dnr/geology/?Theme=subsurf ). The DNR website indicates the site is underlain by Holocene aged Alluvium deposits. The alluvium deposits are described as moderately well sorted deposits of cobble gravel, pebbly sand, and sandy silt. Soil Conditions The subsurface evaluation for this project included three gevtechnical borings and four electronic cone penetrometer tests (CPTs). Boring B-1 was completed tk a' ximum depth of about 51.5 feet below _ existing site grade. Borings B-2 and B-3 were completeda maximum depth of about 11.5 feet below existing site grades. CPT-1 through CPT-4 were completed to maximum depths ranging from about 25 to 28.5 feet below existing site grade. The approxirrr0te loration locations are shown on the Site and Exploration Plan, Figure 1. Soils observed,in tho borings were visually classified in general accordance with the Unified Soil Classification SySterq, ' pescriptive logs of the subsurface explorations and the procedures utilized in the subsurface''`exploration program are presented in Appendix A. A generalized description of soil conditions encountered infhe borings is presented below. Detailed descriptions of soils encountered are provided on the descriptive logs in Appendix A. The description of soil conditions encountered in the CPT explorations presented below is based on measured values of cone tip resistance and sleeve friction, presented as a Friction Ratio, and pore water pressure relative to the theoretical hydrostatic groundwater pressure, presented as a pore pressure ratio. It should be noted that the description of soils is based on empirical correlations. No actual physical soil samples were obtained or observed as part of the CPT explorations. It should be noted that the term "description" used here does not refer to a standard classification system such as the Unified Soil Classification System. The use of CPT should be considered to provide an assessment of soil behavior type and an indirect assessment of soil "description". Boring B-1 was completed in the central portion of the proposed building footprint. Subsurface soil conditions observed in boring B-1 generally consisted of about 8 inches of crushed rock fill underlain by gravelly sand fill extending to about 1.5 feet below existing site grade. Very loose sand with trace silt was observed below the gravelly sand fill extending to about 4 feet below existing site grade. Soil conditions observed below the very loose sand generally consisted of very soft silt and very loose sand extending to about 25 feet below existing Page 2 Zipper Geo Associates, LLC Proposed Reserve at Renton Project Project No. 1187.01 October 18, 2013 site grade. Medium dense to dense gravel with a variable sand content was observed below the very loose sand and very soft silt to the completion depth of about 51.5 feet below existing site grade. Borings B-2 and B-3 were completed in the eastern proposed parking area. Subsurface soil conditions observed in these borings generally consisted of about 3.5 to 4 inches of asphalt concrete pavement underlain by about 8 inches of crushed rock fill. Soil conditions observed below the pavement section generally consisted of very loose sand with variable silt content and soft silt with trace to some peaty organics extending to about 10 feet below the existing ground surface. Both borings were terminated at about 11.5 feet below the existing ground surface in medium dense sand. CPTs 1 through 4 were completed within the proposed building footprint. Due to dense ground conditions within the upper fewfeet of existing site grades, the first few feet of CPTs were "pre -drilled" using hand tools. As a result, CPT data acquisition began at about 5 feet below existing site grade in CPT-1 and about 2 feet in CPT-2 through CPT-4, Surficial soil conditions observed in the "pre -drilled" range of the CPTs consisted of the following: • CPT-1: 1 inch of asphalt concrete pave mentAinderlahby about 4 feet of sand and gravel fill underlain by sand. • CPT-2: 1 inch of asphalt concrete paverrientt-,underlain by about 8 inches of crushed rock fill underlain by sand. • CPT-3: 8 inches gravel underlain bysxa' n • CPT-4: 3 inches of asphalt concrete'°pavement underlain by 6 inches of crushed rock fill underlain by sand. 7._ Below the "pre -drilled" range, soil behavior types indicated by the CPTs within approximately the upper 20 feet of existing site grade were considerably variable and consisted of sensitive fine grained, clay, silty clay to clay, clayey silt to silty clay, sandy silt to clayey silt, silty sand to sandy silt, and sand to silty sand. Recorded tip resistance in the upper 20 feet of existing site grade was typically below 50 tons per square foot (tsf). It should be noted that recorded tip resistances in some of the CPTs within the upper 10 to 15 feet of existing site grades was extremely low (less than 10 tsf) indicating very soft, sensitive fine grained soil behavior type. From about 20 feet to the completion depths of 25 to 28 feet below existing grade, soil behavior types indicated by the CPTs typically consisted of sand and gravelly sand. Tip resistance quickly increased below 20 feet and ranged from about 50 tsf to refusal values in excess of 250 psf. Groundwater Conditions Groundwater was observed in all borings completed for this study. Groundwater monitoring wells were installed in all the borings. Groundwater was measured in each well on October 10, 2013 and the measured depths below existing ground surface (bgs) were as follows: Page 3 Zipper Geo Associates, LLC Proposed Reserve at Renton Project Project No. 1187,01 October 18, 2013 • Boring B-1: Groundwater measured at 6.2 feet bgs. • Boring B-2: Groundwater measured at 6.5 feet bgs. • Boring B-3: Groundwater measured at 6.6 feet bgs. Groundwater observed in the explorations is interpreted to be a regional shallow aquifer within the alluvial soil unit. The thickness of the saturated zone of this shallow aquifer is unknown. Fluctuations in groundwater levels will likely occur due to seasonal variations in the amount of rainfall, runoff and other factors not evident at the time the explorations were performed. Therefore, groundwater levels during construction or at other times in the life of the structure may be higher than indicated on the logs. The possibility of groundwater level fluctuations should be considered when developing the design and construction plans for the project. Summary of laboratory Testing Limited laboratory testing was completed on selected samplos obtained from our borings. The testing C consisted of moisture content on select samples. Moisture content of samples tested from the upper 10 feet of existing site grades in borings B-2 and B-3 indicated rioisture`contents ranging from 13 to 37 percent. Results of moisture content testing are shown on thp.,,borii logs provided in Appendix A. CONCLUSIONS AND RECOMMEN e General Soil conditions observed in geotechnicakixplorations completed for the project are not suitable for shallow foundation support. As a result, we recommend the proposed building be supported on deep foundations such as auger cast piles or alternatively, the loose soils observed in the explorations could be improved with aggregate piers such as the proprietary Geopier system or stone columns. Specific geotechnical engineering recommendations for foundation systems and other earthwork related phases of the project are outlined below. The recommendations contained in this report are based upon the results of field and laboratory testing (which are presented in Appendices A and B), engineering analyses, and our current understanding of the proposed project. ASTM and Washington State Department of Transportation (WSDOT) specification codes cited herein respectively refer to the current manual published by the American Society for Testing & Materials and the current edition of the WSDOT Standard Specifications for Rood, Bridge, and Municipal Construction, (M41-10). Seismic Design Considerations The tectonic setting of western Washington is dominated by the Cascadia Subduction Zone formed by the Juan de Fuca plate subducting beneath the North American Plate. This setting leads to intraplate, crustal, Page 4 Zipper Geo Associates, LLC Proposed Reserve at Renton Project Project No. 1187.01 October 18, 2013 and interplate earthquake sources. Seismic hazards relate to risks of injury to people and damage to property resulting from these three principle earthquake sources. The seismic performance of the development was evaluated relative to seismic hazards resulting from ground shaking associated with a design seismic event as specified in the 2012 International Building Code (IBC). Conformance to the above criteria for seismic excitation does not constitute any kind of guarantee or assurance that significant structural damage or ground failure will not occur if a design seismic event occurs. The primary goal of the IBC seismic design procedure is to protect life and not to avoid all damage, since such design may be economically prohibitive. Following a major earthquake, a building may be damaged beyond repair, yet not collapse. The results of our seismic hazard analyses and recommended seismic design parameters are presented in the following sections. Ground Surface Rupture: Based on our review of the USGS Quaternary age fault database for Washington State, there does not appear to be a mapped Quaternary fault within a 10 mile radius of the site. Based on the reviewed database, the risk of ground surface rupture at the site appears to be low. Landsliding: Based on the relatively flat topography -of the '§4e and surrounding vicinity, the risk of earthquake -induced landsliding is low. Soil Liquefaction: Liquefaction is a phenomeK wherein saturated cohesionless soils build up excess pore water pressures during earthquake ldAdidg. iquefaction typically occurs in loose soils, but may occur in denser soils if the ground shaking'.J.s sufficiently strong. The potential hazardous impacts of liquefaction include liquefaction-induci4ketflsement and lateral spreading. ZGA completed a liquefaction analysis based on ground motion design parameters as specified in the 2012 International Building Code. Specifically, our analysis used the following ground motion parameters. • PGA = Sos/2.5 = 0.38g • Earthquake Magnitude = 7.0 Our liquefaction analysis was completed in general accordance with the "simplified procedure" as outlined in Liquefaction Resistance of Soils: Summary Report from the 1996 NCEER and 1998 NCEER/NSF Workshops on Evaluation of Liquefaction Resistance of Soils (Youd and Idriss, 2001). Soils observed boring B-1 between about 25 feet below existing site grade and the completion depth of about 51.5 feet consisted of medium dense gravels with very little fines content. It is our opinion that the risk of liquefaction in the gravels below 25 feet is low, Our opinion regarding the risk of liquefaction in gravels below 25 feet is based on measured shear wave velocity obtained in CPT-3 at a depth of 22 feet. The measured shear wave velocity at 22 feet in CPT-3 was approximately 900 feet per second (ft/sec). The overburden stress -corrected shear wave velocity in accordance with equation 21 (Youd and Idriss, 2001) is approximately 950 ft/sec. Figure 9 of Youd and Idriss, 2001 indicates that no liquefaction has Page 5 Zipper Geo Associates LLC Proposed Reserve at Renton Project Project No_ 1187.01 October 18, 2013 been observed at sites with overburden -corrected values of shear wave velocity greater than about 650 ft/sec. Shear wave velocities in CPT-3 were determined through seismic cone penetration tests (SCPT) completed at specific intervals. The results of SCPT testing are provided in Appendix A. Our liquefaction analyses indicates that the risk of liquefaction in zones of soil below the groundwater table within the upper 25 feet of existing site grade is high. We estimate that liquefaction -induced settlement resulting from IBC ground motions at the site could be on the order of 6 to 12 inches. Liquefaction settlements could result in damage to improvements supported on grade and underground utilities. 18C Seismic Design_ Parameters: Based on site location and soil conditions, the values provided below are recommended for seismic design. The values provided below are based on the 2012 IBC as the building code reference document. 18C requires a site specific ground motion analysis for sites with liquefiable soils. However, for structures with a fundamental period of vibration equal to or less than 0.5 seconds, site classification may be determined without regard to liquefaction. The values provided below assume �r the building will have a fundamental period of vibration less -than or equal to 0.5 seconds. , 3 k. SUMMARY of IBC SEISMIC IGN PARAMETERS Parameter Value 2012 IBC Site Classification' F S, Spectral Acceleration for a Short Perio4e 1,441 g (Site Class B) S15pectral Acceleration for a 1-Second Per%o 0.539 g (site Class B) Fa Site Coefficient for a Short Period 1.000 (Site Class D) F,Site Coefficient for a 1-Second Period 1.500 (Site Class D) SMs Maximum considered spectral response 1.441 g (Site Class D) acceleration for a Short Period Sm, Maximum considered spectral response 0.808 g (Site Class D) acceleration for a 1-Second Period Sos Five -percent damped design spectral response 0.961 g (Site Class D) acceleration for a Short Period 51)i Five -percent damped design spectral response 0.539 g (Site Class D) acceleration for a 1-Second Period 1. In general accordance with the 2012 International Building Code, Table 1613.5.2. IBC Site Class is based on the average characteristics of the upper 100 feet of the subsurface profile. The borings completed for this study extended to a maximum depth of 51.5 feet below grade. ZGA therefore determined the Site Class assuming that medium dense alluvial soils extend to 100 feet as suggested by published geologic maps for the project area. Page 6 Zipper Geo Associates LLC Proposed Reserve at Renton Project Project No_ 1187.01 October 18, 2013 Lateral Spread: Lateral spreading is a phenomenon in which soil deposits which underlie a site can experience significant lateral displacements associated with the reduction in soil strength caused by soil liquefaction. This phenomenon tends to occur most commonly at sites where the soil deposits can flow toward a "free -face", such as a water body. Due to the lack of a "free -face" condition, the risk of lateral spreading at the site is low for the IBC design earthquake. Site Preparation Erosion Control Measures: Stripped surfaces and soil stockpiles are typically a source of runoff sediments. We recommend that silt fences, berms, and/or swales be installed around the downslope side of stripped areas and stockpiles in order to capture runoff water and sediment. If earthwork occurs during wet weather, we recommend that all stripped surfaces be covered with straw to reduce runoff erosion, whereas soil stockpiles should be protected with anchored plastic sheeting. Temporary Drainage: Stripping, excavation, grading, and subgrade preparation should be performed in a manner and sequence that will provide drainage at all times apd provide proper control of erosion. The site should be graded to prevent water from ponding in 90struction areas and/or flowing into and/or �y over excavations_ Exposed grades should be crowned,,s. pad, and smooth -drum rolled at the end of each day to facilitate drainage if inclement weather is forecasted. Accumulated water must be removed from subgrades and work areas immediately and prior• olie 6rming further work in the area. Equipment access may be limited and the amount of oil r red unfit for use as structural fill may be greatly increased if drainage efforts are not acco.Mpllie3Vi a timely manner. Demolition, Clearing, and Stripping: Weer ect some limited clearing and stripping will be completed in areas of existing landscape islands. We recommend all roots and organic rich topsoil be removed from areas where existing landscape islands will be removed. We expect demolition to include removal of existing concrete curbs and other minor existing above ground utility structures. These items should be removed and properly disposed of offsite. Existing asphalt concrete pavement covers a significant portion of the proposed building footprint. The existing asphalt may pose penetration difficulties for deep foundation or ground improvement drilling equipment. We recommend existing asphalt concrete pavements be ground, full depth, and removed from the building footprint. We expect some existing underground utilities will be abandoned as part of the project work. We recommend existing utilities be abandoned by full removal or grouting in place. Sub.grade Preparation: Once site preparation is complete, all areas that are at design subgrade elevation or areas that will receive new structural fill should be compacted to a firm and unyielding condition. Once compacted, subgrades should be evaluated through proof rolling with a loaded dump truck or heavy rubber -tired construction equipment weighing at least 20 tons to assess the subgrade adequacy and to detect soft and/or yielding soils. In the event that soft or yielding areas are detected during proof rolling, Page 7 Zipper Geo Associates, LLC Proposed Reserve at Renton Project Project No. 1187.01 October 18, 2013 the upper 12 inches of subgrade should be scarified, moisture conditioned and re -compacted as necessary to obtain at least 95 percent of the maximum laboratory density (per ASTM D1557) and a firm, non - yielding condition. Those soils which are soft, yielding, or unable to be compacted to the specified criteria should be over -excavated and replaced with suitable material as recommended in the Structural Fill section of this report. As an alternate to subgrade compaction during wet site conditions or wet weather, the upper 12 inches of subgrade should be overexcavated to a firm, non -yielding and undisturbed condition and backfilled with compacted imported structural fill consisting of free -draining Gravel Borrow or crushed rock. In the event that wet site conditions preclude proof rolling the subgrade, a ZGA representative should evaluate the conditions via hand probing. Earthwork should be completed during drier periods of the year when soil moisture content can be controlled by aeration and drying. If earthwork or construction activities take place during extended periods of wet weather, exposed site soils will quickly become unstable or not be compactable. In the event the exposed subgrade becomes unstable, yielding, or unable to be compacted due to high moisture conditions, we recommend that the materials be removed to i sufficient depth in order to develop stable subgrade soils that can be compacted to the minimum rec9Pended levels. The severity of construction problems will be dependent, in part, on the precautiogs that are: taken by the contractor to protect the subgrade soils. Freezing Conditions: If earthwork takes place duldngfreezing conditions, all exposed subgrades should be allowed to thaw and then be compacted prioF r,� lacing subsequent lifts of structural fill. Alternatively, the frozen material could be strippd' frond the subgrade to expose unfrozen soil prior to placing subsequent lifts of fill or foundation co�i tponents. The frozen soil should not be reused as structural fill until allowed to thaw and adjusted to the proper moisture content, which may not be possible during winter months. Structural Fill Materials and Preparation Structural fill includes any material placed below foundations and pavement sections, within utility trenches, and behind retaining walls. Prior to the placement of structural fill, all surfaces to receive fill should be prepared as previously recommended in the Site Preparation section of this report. Laboratory Testing: We recommend that representative samples of proposed imported materials be submitted for laboratory testing at least one week prior to use. Tests completed on the samples should include moisture content, grain size analysis and modified proctor. These tests will provide an indication of the suitability of the material for use as structural fill and an indicator of support characteristics. Reuse of Site Soils as Structural Fill: Soils observed in the geotechnical borings generally contained a significant fraction of fines and appeared wet of optimum moisture content for compaction at the time the explorations were completed. Reuse of site soils site soils as structural fill will only be feasible during Page 8 Zipper Geo Associates, LLC Proposed Reserve at Renton Project Project No. 1187,01 October 18, 2013 dry summer months. Even during dry summer months, site soils will likely require moisture conditioning (drying) in order for reuse as structural fill. During wet weather, we do not expect site soils to be suitable for reuse as structural fill. Soils excavated from below the groundwater table will not be suitable for reuse as structural fill without significant drying or chemical treatment. Drying of over -optimum moisture soils may be achieved by scarifying or windrowing surficial materials during extended periods of dry weather. If encountered, soils which are dry of optimum may be moistened through the application of water and thorough blending to facilitate a uniform moisture distribution in the soil prior to compaction. We recommend that site soils used as structural fill have less than 4 percent organics by weight and have no woody debris greater than Y: inch in diameter. We recommend that all pieces of organic material greater than Y2 inch in diameter be picked out of the fill before it is compacted. Any organic -rich soil derived from earthwork activities should be utilized in landscape areas or wasted from the site. , Imported Structural Fill: Imported structural fill may berm wired for raising site grades or for other reasons. The appropriate type of imported structural fillWil,l.be r4ostly dependent on weather and desired support characteristics. During dry weather, lesser q o,lty fill such as Common Borrow can be used. However, during wet weather, higher quality, free drairiir i-fill such as Gravel Borrow is typically required. The following paragraphs present general r - rr(m. eklations regarding imported structural fills. During extended periods of dry we ther,'Oerecommend imported fill, at a minimum, meet the requirements of Common Borrow as ikoed in Section 9-03.14(3) of the 2012 Washington State Department of Transportation, Standard Specifications for Road, Bridge, and Municipal Construction (WSDOT Standard Specifications). During wet weather, higher -quality structural fill might be required, as Common Borrow may contain sufficient fines to be moisture sensitive. During wet weather we recommend that imported structural fill meet the requirements of Gravel Borrow as specified in Section 9-03.14(1) of the WSDOT Standard Specifications. Retaining Wall Backfill: Retaining walls should include a drainage fill zone extending at least two feet back from the back face of wall for the entire wall height. The drainage fill should meet the requirements of Gravel Backfill for Walls as specified in Section 9-03.12(2) of the WSDOT Standard Specifications. Moisture Content: The suitability of soil for use as structural fill will depend on the time of year, the moisture content of the soil, and the fines content (that portion passing the U.S. No. 200 sieve) of the soil. As the amount of fines increases, the soil becomes increasingly sensitive to small changes in moisture content. Soils containing more than about 5 percent fines (such as the near -surface on -site soils) cannot be consistently compacted to the appropriate levels when the moisture content is more than approximately 2 percent above or below the optimum moisture content (per ASTM D1557). Optimum Page 9 Zipper Geo Associates, LLC Proposed Reserve at Renton Project Project No. 1187.01 October 18, 2013 moisture content is that moisture content which results in the greatest compacted dry density with a specified compactive effort. Fill Placement: Structural fill should be placed in horizontal lifts not exceeding 10 inches in loose thickness. Each lift of fill should be compacted using compaction equipment suitable for the soil type and lift thickness. Each lift of fill should be compacted to the minimum levels recommended below based on the maximum laboratory dry density as determined by the ASTM D1557 Modified Proctor Compaction Test. Moisture content of fill at the time of placement should be within plus or minus 2 percent of optimum moisture content for compaction as determined by the ASTM D1557 test method. Compaction Criteria: Our recommendations for soil compaction are summarized in the following table. Structural fill for roadways and utilitytrenches in municipal rights -of -way should be placed and compacted in accordance with the jurisdiction codes and standards. We recommend that a geotechnical engineer be present during grading so that an adequate number of density tests may be conducted as structural fill placement occurs. In this way, the adequacy of the earthwork may be evaluated as it proceeds. RECOMMENDED SOIL ACT N LEVELS Location Minimum percent Compaction* Stripped native subgrade soils, prior to fill oacer nt (upper 12 inches), except infiltration areas ` Firm and Unyielding Condition Footing subgrades, fill or native (upper 12fn 95 All fill below building floor slabs and fours a;cs s 95 Upper 2 feet of fill below floor slabs and pavements 95 Pavement fill below two feet 90 Retaining wall backfill less than 3 feet from wall 90 Retaining wall backfill more than 3 feet from wall 95 Upper two feet of utility trench backfiI1 95 Utility trenches below two feet 90 Landscape Areas 90 * ASTM DI557 Modified Proctor Maximum Dry Density Placing Fill on Slopes: Permanent fill placed on slopes steeper than 5H:\1V (Horizontal: Vertical) should be keyed and benched into natural soils of the underlying slope. We recommend that the base downslope key be cut into undisturbed native soil. The key slot should be at least 8 feet wide and 3 feet deep. The hillside benches cut into the native soil should be at least 4 feet in width. The face of the embankment should be compacted to the same relative compaction as the body of the fill. This may be accomplished by over -building the embankment and cutting back to the compacted core. Alternatively, the surface of the slope may be compacted as it is built, or upon completion of the embankment fill placement. Page 10 Zipper Geo Associates, LLC Proposed Reserve at Renton Project Project No. 1187.01 October 18, 2013 Construction Dewatering Groundwater was observed in all explorations completed for this project. Groundwater flow rates into excavations that extend below the groundwater table at this site will be moderate to high. Dewatering should be expected for this project for excavations that extend below the groundwater table. The appropriate type of dewatering system should be determined by the contractor based on the conditions encountered, and should be designed and maintained by the contractor. Lowering the groundwater level during dewatering operations may cause settlement of the ground surface outside of excavations. The magnitude and aerial extent of such settlement will be a function of the drawdown radius, the duration of dewatering, and the actual soil conditions encountered in the field. Contractor -designed dewatering systems should specifically address ground surface settlements as such settlements may cause damage to adjacent pavements, structures, and utilities. The quality of groundwater discharge should be in accordance with Washington State Department of Ecology Standards. Underground Utilities We recommend that utility trenching conform to all applied %federal, state, and local regulations, such as OSHA and WISHA, for open excavations. Trench ",cavation safety guidelines are presented in WAC Chapter 296-155 and WISHA RCW Chapter 49.17. ,.. Trench Dewatering: Excavations for r uti I sd. . an,. underground structures that extend below the groundwater table should be expected..tQ :rtpunter moderate to heavy groundwater seepage. Some caving of utility trench sidewalls should be'intfcipated in association with groundwater seepage. We recommend that any excavations within`Wundwater seepage zones be undertaken only when suitable dewatering equipment and temporary excavation shoring are available, or where space is available to flatten the sidewalls. Dewatering should be expected for this project if utilities will extend below the groundwater table. The appropriate type of dewatering system should be determined by the contractor based on the conditions encountered, and should be designed and maintained by the contractor. Utility Subgrade Preparation: We recommend that all utility subgrades be firm and unyielding and free of all soils that are loose, disturbed, or pumping. Such soils should be removed and replaced, if necessary. All structural fill used to replace over -excavated soils should be compacted as recommended in the Structural Fill section of this report. If utility foundation soils are soft, we recommend that they be over - excavated 12 inches and replaced with crushed rock. Structures such as manholes and catch basins which extend into soft soils should be underlain by at least 12 inches of crushed rock fill compacted to at least 90 percent of the modified Proctor maximum dry density. This granular material could consist of crushed rock, quarry spalls, or coarse crushed concrete. Alternatively, quarry spalls or pea gravel could be used until above the water level. It may be necessary Page 11 Zipper Geo Associates, LLC Proposed Reserve at Renton Project Project No. 1187.01 October 18, 2013 to place a geotextile fabric over the native subgrade soils if they are too soft, to provide a separation between the bedding and subgrade soils. Bedding: We recommend that a minimum of 4 inches of bedding material be placed above and below all utilities or in general accordance with the utility manufacturer's recommendations and local ordinances. We recommend that pipe bedding consist of Gravel Backfill for Pipe Zone Bedding as specified in Section 9-03.12(3) of the WSDOT Standard Specifications. All trenches should be wide enough to allow for compaction around the haunches of the pipe, or material such as pea gravel should be used below the spring line of the pipes to eliminate the need for mechanical compaction in this portion of the trenches. If water is encountered in the excavations, it should be removed prior to fill placement. Trench Backfill: Materials, placement and compaction of utility trench backfill should be in accordance with the recommendations presented in the Structural Fill section of this report. We recommend that the initial lift thickness not exceed one foot unless recommended by the manufacturer to protect utilities from damage by compacting equipment. Light, hand operated compaction equipment may be utilized directly above utilities if damage resulting from heavier compactiop", quipment is of concern. Temporary and Permanent Slopes Temporary excavation slope stability is a function of- i"'hy:.factors, including; • The presence and abundance of groundwater; • The type and density of the vari � L.,sat ra�a; • The depth of cut; • Surcharge loadings adjacent to t*6cavation; and • The length of time the excavation remains open. As the cut is deepened, or as the length of time an excavation is open, the likelihood of bank failure increases; therefore, maintenance of safe slopes and worker safety should remain the responsibility of the contractor, who is present at the site, able to observe changes in the soil conditions, and monitor the performance of the excavation. It is exceedingly difficult under the variable circumstances to pre -establish a safe and "maintenance -free" temporary cut slope angle. Therefore, it should be the responsibility of the contractor to maintain safe temporary slope configurations since the contractor is continuously at the job site, able to observe the nature and condition of the cut slopes, and able to monitor the subsurface materials and groundwater conditions encountered. Unsupported vertical slopes or cuts deeper than 4 feet are not recommended if worker access is necessary. The cuts should be adequately sloped, shored, or supported to prevent injury to personnel from local sloughing and spalling. The excavation should conform to applicable Federal, State, and Local regulations. Page 12 Zipper Geo Associates, LLC Proposed Reserve at Renton Project Project No. 118T01 October 18, 2013 According to Chapter 296-155 of the Washington Administrative Code (WAC), the contractor should make a determination of excavation side slopes based on classification of soils encountered at the time of excavation. Temporary cuts may need to be constructed at flatter angles based upon the soil moisture and groundwater conditions at the time of construction. Adjustments to the slope angles should be determined by the contractor at that time. We recommend that all permanent cut or fill slopes constructed in native soils or with imported structural fill be designed at a 2H:1V (Horizontal: Vertical) inclination or flatter. If applicable, interior slopes of stormwater ponds should be inclined no steeper than 3H:1V. All permanent cut and fill slopes should be adequately protected from erosion both temporarily and permanently. If the slopes are exposed to prolonged rainfall before vegetation becomes established, the surficial soils will be prone to erosion and possible shallow sloughing. We recommend covering permanent slopes with a rolled erosion protection material, such as lute matting or Curiiex II, if vegetation has not been established by the regional wet season (typical ly_.November through May). Building Foundation Support The soils observed in our explorations extending to a Idoth of about 20 to 25 feet below existing site grades are not suitable for shallow foundation supp rfiviti out excessive differential settlement resulting from static loads as well as liquefaction-ind d ' tt ent and strength loss. Therefore, we recommend the building be supported on deep found, 'o.. A rnatively, stone columns, Geopiers or other methods _ of ground improvement could be con ere o mprove existing soils to a condition suitable for shallow foundation support. Recommendations nd further discussion for deep foundations and ground improvement are provided below. Auger Cast -in -Place Concrete Piles For deep foundations, it is our opinion that auger cast -in -place concrete piles (ACIP piles) are suitable for the project. Recommendations for ACIP pile allowable compressive and uplift capacities for various pile diameters and installation depths are provided in the attached Figures 2 through 5. The recommendations for pile capacities (compressive, uplift, and lateral) assume a minimum pile spacing of 3D where D is the diameter of the pile. The minimum embedment depth of ACIP piles should be based on the recommendations presented below for lateral pile resistance. Additional recommendations and considerations for ACIP piles are provided below. Downdrag Loads: Liquefaction -induced settlement will result in down drag loads on ACIP piles for the seismic case. The downdrag loads very from 30 to 50 kips depending on pile diameter. The seismic capacities presented on Figure 2 have been reduced to account for downdrag caused by liquefaction. Page 13 Zipper Geo Associates, LLC Proposed Reserve at Renton Project Project No. 1187.01 October 18, 2013 Lateral Resistance: Resistance to lateral loads can be developed through passive earth pressure on embedded foundation elements and lateral resistance of piles embedded in soil. Passive earth pressure on foundation elements may be calculated assuming an ultimate passive resistance of 400 pounds per cubic foot equivalent fluid pressure (triangular distribution). We recommend that passive resistance be neglected in the upper 18 inches of embedment. For allowable stress design, we recommend minimum 1.5 safety factor be used on passive earth pressures. The table below provides recommendations for lateral pile resistance. The recommendations below assume pile heads will be "fixed" into pile caps, Pile Pile Head Minimum Embedment Point of Fixity Allowable Lateral Diameter Deflection Depth Below Existing {depth below existing Load (kips) (in) (in) Site Grade grade in feet) (ft) 16 %z 40 26 8 18 %x 40 29 10 24 %: 50 36 16 oz. Foundation Depth and Width: For frost protection, the iott.om dfall exterior footings should bear at least 18 inches below the lowest adjacent outside grade whor as the bottoms of interior footings should bear at least 12 inches below the surrounding slab surfa' -vel. We recommend that all continuous wall and isolated column footings be at least 12 and ;A, i he wide, respectively. Estimated Foundation Settlement: Estfmate total settlement of foundations supported on ACIP piles as recommended in this report is approximately one inch or less. Estimated differential settlements are approximately % inch or less in 40 feet. ACIP Pile Construction Considerations Auger cast piles should be installed to the recommended pile tip elevations using a continuous -flight, hollow -stem auger. As is common practice, the pile grout would be pumped under pressure through the hollow stem as the auger is withdrawn. We recommend that the auger cast piles be installed by a contractor experienced in their placement and using suitable equipment. Grout pumps must be fitted with a volume -measuring device and pressure gauge so that the volume of grout placed in each pile and the pressure head can be easily determined. While grouting, the rate of auger withdrawal must be controlled such that the volume of grout pumped is equivalent to at least 115 percent of the theoretical hole volume. However, pressure grouting techniques may result in grout volumes in excess of 115 percent of the theoretical volume because the grout may tend to flow out into the loose and soft soil zones. Based on our experience with similar projects in the Renton area, grout volumes in excess of 130 to 170 percent are not uncommon in the area. Page 14 Zipper Geo Associates, LLC Proposed Reserve at Renton Project Project No. 1187.01 October 18, 2013 A minimum grout line pressure of 100 psi must be maintained while grouting. Also, a minimum head of grout of 8 feet should be maintained above the auger tip at all times as the auger is being retracted from the hole in order to maintain borehole stability. However, higher heads should be expected based on our experience with similar projects in the Renton area. Our experience with a nearby project indicates that grout heads on the order of 15 to 20 feet were required to maintain bore hole stability. Grout heads on this project resulted in grout volumes on the order of 130 to 170 percent of the theoretical grout volume. We recommend that there be a waiting period of at least sixteen hours between installation of piles spaced closer than about 10 feet center -to -tenter, in order to avoid disturbance of concrete undergoing curing in a previously cast pile. Although no apparent obstructions were encountered within the recommended pile depths in Boring B- 1, obstructions, such as buried logs and stumps, may be encountered during pile installation. The use of pre -excavation or other techniques may be required to deal with obstructions and the contractor should be prepared to use these or other similar procedures where necessary. If pile refusal occurs above the recommended pile tip elevation, our firm should evaluate the llowable capacity of the short pile. It should be noted that the recommended pile tip ele lions a . capacities presented above are based on assumed uniformity of soil conditions across the sit+iere may be unexpected variations in the depth to and characteristics of the supporting soils. In ad ition i7io direct information regarding the capacity of auger cast piles (e.g., driving resistance d s ' tained while this type of pile is being installed. _,_ Therefore, it is particularly important that Ck�e ift-Sllation of auger cast piles be completed under the direct observation of an experiencedgeaechlhicaI engineer. Accordingly, we recommend that pile installation be monitored by a member '&Vstaff who will observe installation procedures and evaluate the adequacy of individual pile installations. Additionally, we recommend construction specification similar to those recommended in Geotechnical Engineering Circular NO. 8, Design and Construction of Continuous Flight Auger Piles (FHWA 2007) be used for the project. Auger cast pile construction at the project site will create saturated spoils that will tend to flow. An appropriate plan should be developed to contain and remove the spoils. Ground Improvement As an alternative to ACIP pile foundation support, ground improvement could be considered. The use of ground improvement would allow the building the building to be supported on conventional shallow foundations. Additionally, the slab could be supported on -grade. Ground improvement is typically completed by a specialty contractor on a design build basis to meet performance criteria (allowable total and differential settlements) established by the owner or structural Page 15 Zipper Geo Associates, LLC Proposed Reserve at Renton Project Project No. 1197.01 October 18, 2013 engineer. The contractor would use the data (boring and CPT logs) in this report as the basis for the specific design, or acquire additional data if they deem necessary. Ground improvement types can generally be separated into two categories; densification and reinforcement. Methods for densification include dynamic compaction, vibro replacement stone columns, drainage and surcharge, and compaction grouting. Methods for reinforcement include vibro replacement stone columns, deep soil mixing, compaction grouting chemical grouting, and jet grouting. The appropriate method for a specific project is a function of many parameters including gradation of the treatment soils, ground water conditions, pre-treatment soil strength, plasticity of the treatment soils, thickness/depth of treatment soils, and required performance criteria. Dynamic compaction is not feasible for this project as it would create significant ground vibrations that could damage the adjacent existing building to the north. Drainage and surcharge are not feasible for this project as surcharge cannot adequately density potentially liquefiable soils. Considering the thickness of soils to be treated for this project (roughly 20 to 30 feet), we expect that vibro replacement stone columns working to both density potentially liquefiable soils and reinforce soft, fine-grained soils can likely meet performance requirements and will be more econginical than other alternatives. However, we recommend the project team consult with local groundTr( rovement contractors (such as Hayward Baker, Geopier, and DBM) to evaluate cost and feasibihty'4fvc [Yd improvement options. For design of ground improvement for the project, we recomm 5pd-Qie 1roject team and ground improvement contractors consider the following:r • Performance Criteria: We repxiiend the project team provide performance criteria to perspective ground improvement contractors including allowable static and seismic total and differential foundation settlements and foundation loads. • Geotechnical Information: Perspective ground improvement contractors should be provided a copy of this report. However, perspective ground improvement contractors should be provided an opportunity to acquire additional geotechnical data or request additional geotechnical data to satisfy their understanding of subsurface soil and groundwater conditions at the site from which their design and cost will be largely based. • Existing Site Conditions: Perspective ground improvement contractors should review and understand existing site conditions that may impact their work. Of particular note is existing underground utilities and an existing building located along the north property line that is located within about 20 feet of the proposed north building line. Based on our review of building plans obtained from the City of Renton, we understand the existing building is pile -supported. We recommend perspective ground improvement contractors review available information from the city of Renton concerning this existing building. Page 16 Zipper Geo Associates_,_ LLC Proposed Reserve at Renton Project Project No. 1187.01 October 18, 2013 • Verification Testinp,: The selected ground improvement contractor should be required to complete some form of post -installation verification testing (such as load tests) to verify their design and design assumptions. Building On -Grade Concrete Floor Slab The following sections provide recommendations for on -grade floor slabs. Slab Support: Subsurface soil conditions are not suitable for support of the lower level building floor slab without unacceptable differential settlement. We recommend the building floor slab be supported on ACIP piles. Alternatively, if ground improvement is completed under the floor slab, the slab could be supported on grade. Recommendations for ACIP piles and ground improvement are discussed above. Subgrade Preparation: Slab subgrades should be prepared in accordance with the Site Preparation and Structural Fill sections of this report. Capillary Break: To provide a capillary break, uniform slag 4earing surface, and a minimum subgrade modulus of 150 pci, we recommend the on -grade slab4,6e :nde�ain by a 6-inch thick layer of compacted, well -graded granular fill contain less than 5 percent fin based on that soil fraction passing the U.S. No. 4 sieve. Alternatively, a clean angular gravel such: r s � aggregate per WSDOT: 9-03.1(4) C could be used for this purpose. Alternative capilla ak Materials should be submitted to the geotechnical engineer for review and approval b Vapor Retarder: The use of a vapor reta� should be considered beneath concrete slabs on grade that will be covered with wood, tile, carpet or other moisture sensitive or impervious coverings, or when the slab will support equipment sensitive to moisture or is otherwise considered moisture -sensitive. When conditions warrant the use of a vapor retarder, the slab designer and contractor should refer to ACI 302 and/or ACI 360 for procedures and cautions regarding the use and placement of a vapor retarder. Backfilled Permanent Retaining Walls We expect the project may include backfilled, cast -in -place (0.p.) concrete retaining walls or other walls. For backfilled permanent foundation walls associated with the building, refer to information above for foundation support. Additional recommendations for these structures are provided below. If other, site retaining walls not associated with the building are required, we recommend we be consulted for additional recommendations regarding foundation support. Lateral Earth Pressures: The lateral soil pressures acting on backfilled retaining wails will depend on the nature and density of the soil behind the wall, and the ability of the wall to yield in response to the earth loads. Yielding walls (i.e. walls that are free to translate or rotate) that are able to displace laterally at least 0.001H, where H is the height of the wall, may be designed for active earth pressures. Non -yielding Page 17 Zipper Geo Associates,_LLC Proposed Reserve at Renton Project Project No, 1187.01 October 18, 2013 walls (i.e. walls that are not free to translate or rotate) should be designed for at -rest earth pressures - Non -yielding walls include walls that are braced to another wall or structure, and wall corners. Assuming that walls are backfilled and drained as described in the following paragraphs, we recommend that yielding walls supporting horizontal backfill be designed using an equivalent fluid density of 35 pcf (active earth pressure). Non -yielding walls should be designed using an equivalent fluid density of 50 pcf (at -rest earth pressure). Design of permanent retaining walls should consider additional earth pressure resulting from the design seismic event. For the seismic case, yielding walls should be designed for an additional uniform (rectangular), seismic earth pressure distribution of 7H and non -yielding walls should be designed for a uniform, seismic earth pressure distribution of 16H. The recommended seismic earth pressure distributions should be added to the above static earth pressure values. The above -recommended lateral earth pressures do not inc J#de the effects of sloping backfill surfaces, surcharges such as traffic loads, other surface loading, or iay static pressures. If such conditions exist, we should be consulted to provide revised earth pres a ecom endations. Adequate drainage measures must be installed to cd1leftnd direct subsurface water away from subgrade walls. All backfilled walls should include a d,fainage aggregate zone extending two feet from the back of wall for the full height of the wall. Tj e;:drainage aggregate should consist of material meeting the requirements of WSDOT 9-03.12(2) Gomel Ba kfill for Walls. A minimum 4-inch diameter, perforated PVC drain pipe should be provided at the basfrf backfilled walls to collect and direct subsurface water to an appropriate discharge point. Drain pipe perforations should be protected using a non -woven filter fabric such as Mirafi 140N. Wall drainage systems should be independent of other drainage systems such as roof drains. Drainage Considerations Surface Drainaee: Final site grades should be sloped to carry surface water away from buildings and other drainage -sensitive areas. Additionally, site grades should be designed such that concentrated runoff on softscape surfaces is avoided. Any surface runoff directed towards softscaped slopes should be collected at the top of the slope and routed to the bottom of the slope and discharged in a manner that prevents erosion. Building Perimeter Footing Drains and Retaining Wall Drains: We recommend that the new buildings and retaining walls be provided with a footing drain system to reduce the risk of future moisture problems and the buildup of hydrostatic pressures. The footing drains should consist of a minimum 4-inch diameter, Schedule 40, rigid, perforated PVC pipe placed at the base of the heel of the footing with the perforations facing down. The pipe should be surrounded by a minimum of 6 inches of clean free -draining granular Page 19 Zipper Geo Associates LLC Proposed Reserve at Renton Project Project No. 1187.01 October 18, 2013 material conforming to WSDOT Standard Specification 9-03.12(4), Gravel Backfill for Drains. A non -woven filter fabric such as Mirafi 140N, or equivalent, should envelope the free -draining granular material. At appropriate intervals such that water backup does not occur, the drainpipe should be connected to a tightline system leading to a suitable discharge. Cleanouts should be provided for future maintenance. The footing drain system must be independent from the roof drain system. Pavements Pavement Life and Maintenance: It should be realized that asphaltic pavements are not maintenance - free. The following pavement sections represent our minimum recommendations for an average level of performance during a 20-year design life; therefore, an average level of maintenance will likely be required. A 20-year pavement life typically assumes that an overlay will be placed near the midpoint of that 20 year life span. Thicker asphalt, base, and subbase courses would offer better long-term performance, but would cost more initially. Conversely, thinner courses would be more susceptible to "alligator" cracking and other failure modes. As such, pavement design can be considered a compromise between a high initial cost and low maintenance costs versua low initial cost and higher maintenance costs. The recommendations presented below are based on AASHTO Low -Volume Road Design <. methodologies as presented in the 1993 AASHTO Guicl,Oor Design of Pavement Structures. Traffic and Reliability: Our design assumes 100,00 ` l, kp�bquivalent single axle loads over the life of the . pavement along the main access roads and a0755 rolldbility. Soil Design Values: Pavement subgracW soil r anticipated to consist of dense to very dense Glacial Till soils or site soils placed as compacted st Iral fill. Our analysis assumes the pavement subgrades with a minimum California Bearing Ration (CBR) value of 15. Recommended Pavement Sections: For light duty pavements (parking stalls), we recommend 2 inches of asphalt concrete over 4 inches of crushed rock base course. For heavy duty pavements (main access roads, truck delivery routes, etc,), we recommend 3 inches of asphalt concrete over 6 inches of crushed rock base course. Materials and Construction: We recommend the following regarding asphalt pavement materials and pavement construction_ • Subgrade Preparation: Upper 12 inches of pavement subgrade should be prepared in accordance with the recommendations presented in the Subgrade Preparation section of this report. • Asphalt Concrete: We recommend that the asphalt concrete conform to Section 9-02.1(4) for PG 58-22 or PG 64-22 Performance Graded Asphalt Binder as presented in the 2012 WSDOT Standard Specifications. We also recommend that the gradation of the asphalt aggregate conform to the Page 19 Zipper Geo Associates LLC Proposed Reserve at Renton Project Project No. 1187.01 October 18, 2013 aggregate gradation control points for Y:-inch mixes as presented in Section 9-03.8(6), HMA Proportions of Materials. • Base Course: We recommend that the crushed aggregate base course conform to Section 9- 03.9(3) of the WSDOT Standard Specifications. * Compaction: All base material should be compacted to at least 95 percent of the maximum dry density determined in accordance with ASTM: D 1557. We recommend that asphalt be compacted to a minimum of 92 percent of the Rice (theoretical maximum) density or 96 percent of Marshall (Maximum laboratory) density. CLOSURE The analysis and recommendations presented in this report are based, in part, on the explorations completed for this study. The number, location, and depth of the explorations were completed within the constraints of budget and site access so as to yield the information to formulate our recommendations. Project plans were in the preliminary stage at the tipii "Ns report was prepared. We therefore recommend Zipper Geo Associates, LLC be provide,607V opportunity to review the final plans and specifications when they become available in orider to ssess that the recommendations and design considerations presented in this report have bb,99en p e interpreted and implemented into the project design. The performance of earthwork, struct I fill oundations, and pavements depend greatly on proper site preparation and construction procedures.' a recommend that Zipper Geo Associates, LLC be retained to provide geotechnical engineering services during the earthwork -related construction phases of the project. If variations in subsurface conditions are observed at that time, a qualified geotechnical engineer could provide additional geotechnical recommendations to the contractor and design team in a timely manner as the project construction progresses. This report has been prepared for the exclusive use of Canddle Development, and their agents, for specific application to the project discussed and has been prepared in accordance with generally accepted geotechnical engineering practices. No warranties, express or implied, are intended or made. Site safety, excavation support, and dewatering requirements are the responsibility of others. In the event that changes in the nature, design, or location of the project as outlined in this report are planned, the conclusions and recommendations contained in this report shall not be considered valid unless Zipper Geo Associates, LLC reviews the changes and either verifies or modifies the conclusions of this report in writing. Page 20 N sucF w rzFr 1 LEGEND: &t BORING NUMBER AND APPROXIMATE LOCATION FESEROF AT FW C CPT-1 �S Assn Aw�ee SaAn GPT TEST NUMBER AND arm,. waargr, APPROXIMATE LOCATION 81E AND EXPLORATION PLAN QPTL X I A.3 hd rro 1910� Dyyr Oro AuxN:w. ILC FIGURE ADATEO wTOCAD FkF PROM RY CG FNGWFFRNG t9R23 .1Bm Are. W. S,rte L Y"""ooe. WA wl i a r APPENDIX A SUBSURFACE EXPLORATION PROCEDURES & LOGS APPENDIX A SUBSURFACE EXPLORATION PROCEDURES AND LOGS Field Exploration Description Our field exploration for this project included 3 geotechnical test borings and 4 electronic cone penetrometer tests (CPT) completed between September and October, 2013. The approximate exploration locations are shown on the Site and Exploration Plan, Figure 1. Exploration locations were determined by measuring off of existing site features shown on a topographic survey provided by CG Engineers. The approximate ground surface elevation at the exploration locations was determined by interpolating from topographic information shown on the above -referenced topographic survey. The exploration locations and elevations should be considered accurate only to the degree implied by the means and methods used to define them. The vertical datum for the referenced survey is not known. Boring Procedures The borings were advanced using a drill rig operated by an independent drilling company working under subcontract to ZGA. The borings were advanced using hollow stem auger drilling methods and drilling 4 fluids (fluid cement grout) to limit heave inside the aupts An engineering geologist or geotechnical engineer from our firm continuously observed the borings; logg the subsurface conditions encountered, and obtained representative soil samples. All sampl'i ,were stored in moisture -tight containers and transported to our laboratory for further evaluationd Ming. Samples were obtained by means of the Standard Penetration Test at 2.5- to 5-foot ir1wrypisvroughout the drilling operation. The Standard Penetration Test (ASTK D-15 rocedure consists of driving a standard 2-inch outside diameter steel split spoon sampler 18 ir'ekes Tito the soil with a 140-pound hammer free falling 30 inches. The number of blows required to drive the sampler through each 6-inch interval is recorded, and the total number of blows struck during the final 12 inches is recorded as the Standard Penetration Resistance, or "blow count" (N value). If a total of 50 blows are struck within any 6-inch interval, the driving is stopped and the blow count is recorded as 50 blows for the actual penetration distance. The resulting Standard Penetration Resistance values indicate the relative density of granular soils and the relative consistency of cohesive soils. The enclosed boring logs describe the vertical sequence of soils and materials encountered in each boring, based primarily upon our field classifications_ Where a soil contact was observed to be gradational, our logs indicate the average contact depth. Where a soil type changed between sample intervals, we inferred the contact depth, Our logs also graphically indicate the blow count, sample type, sample number, and approximate depth of each soil sample obtained from the boring. If groundwater was encountered in a borehole, the approximate groundwater depth, and date of observation, are depicted on the log. CPT Procedures The CPT explorations were advanced with an electric cone penetrometer, using a truck -mounted probe rig operated by an independent firm working under subcontract to ZGA. Due to the presence of gravelly fill soils mantling the site, each probe location was predrilled to variable depths. An engineering geologist from our firm continuously observed the probes while electronic monitoring equipment in the probe rig automatically logged the subsurface conditions. After each probe was completed, the probehole was backfilled with a bentonite and water grout. Throughout the probing operation, soil and groundwater properties were measured at 5-centimeter depth intervals by means of the Cone Penetration Test (CPT) as per ASTM; D-3441. This testing procedure involves pushing a standard 1.5-inch diameter steel cone penetrometer into the soil with hydraulic rams. A cone penetrometer consists of a conical tip, a cylindrical sleeve, and a pressure transducer. As the penetrometer is pushed downward, the tip resistance, sleeve friction, and porewater pressure are measured electronically and plotted as a function of depth. The enclosed CPT logs present vertical plots of measured tip resistance, sleeve friction, porewater pressure and other parameters related and correlated to tip resistance, sleeve friction and porewater pressure. SCPT Procedures A Seismic Cone Penetration test (SCPT) was comp measuring the travel times of body waves propagt and an array of geophones in an in -situ seismic cdc waves (S-waves) and compressional or primerOyes r a%th CPT-3 location. The SCPT consists of tween a wave source and the ground surface istrometer. These body waves comprise shear re waves (P-waves). Seismic waves generated on the surface are` et-ected downhole by three geophones mounted inside the penetrometer. The cone penetration tes' lriefly paused to conduct seismic tests at specific depths. Individual seismic tests include the recording of two opposing shear S-waves and one compression P- wave. Each seismic test is graphically compiled to create a profile of shear wave velocity with depth. Boring Location: See Figure 1, Site and Exploration Plan Drilling Company: Geologic Drill Bare Hole Dia.: 6" To EIS evation: Approximately 26.5 FT Drilling Method: HAS Hammer Type: Auto Date Drilled: 9/1112013 Drill Rig: Track Logged by: RAR SOIL DESCRIPTION PENETRATION RESISTANCE (b{awstioat) _ U) 3 JA w o Standard Penetration Test w The stratification lines represent the approximate boundaries z 0- ' d $ 'a L Hammer Weight and Drop: U (D between soil types. The transition may be gradual. Refer to Q D 3 report text and appendices for additional information. 0) 0 —�° 0 20 40 rm D 8 inches Crushed Rock `Loose, moist, brown, gravelly SAND (fill) ------------------------------------------ Very loose, moist, orange -brown, fine SAND with trace silt s 1 I 12" I 111 I 4 I I 5 Very soft, saturated, orange -gray, sandy SILT n II 5-2 I 12" ♦ �... 1 I ..}.. -..1 L-._1-_, _ . 1 { - . -il .; { L _L_..J- 2 - - - -- 9 Y Y Veryloose, saturated gray -brown, silty fine SAND I .. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - .. 10 Very soft, saturated, gray, sandy SILT I i S-4 I 12" r-rTT l 1--- --T-T--;-t �- HIM -� 15 ++ I 1 + +I,-4- Very soft, saturated, gray, sandy SILT with thin layers of si fine SAND S-5 181, 1 F 1.___ } I -� I i ' 20 S-6 12"�i H 1 7 ___________________________________________ Loose to medium dense, saturated, gray, medium to coarse j--t Til, -r I I-s ti } I +j — IF7 GRAVEL with some sand i I I r} 1- 1-II i} 25 SAMPLE LEGEND GROUNDWATER LEGEND 0 % Fines (<0.075 mm) I2-inch 0. D. split spoon sample Fri -J Clean Sand 0 % Water (Moisture) Content �3-inch I.D. Shelby tube sample Bentonite Plastic Limit Liquid Limit Grout/Concrete Natural Water Content ® Screened Casing Reserve at Renton TESTING KEY ❑ Blank Casing 325 Rainer Ave. South GSA = Grain Size Analysis Z Groundwater level at Renton, WA time of drilling (ATD) or 20QW = 200 Wash Analysis ? on date of Date: September, 2013 Project No.: 1187.01 Consol. = Consolidation Test N measurement. Zipper Geo Associates BORING All. = Atterberg Limits B-� 19023 36th Ave. W, Suite D LAG; Lynnwood, WA Page 1 of 3 Boring Location See Figure 1, Site and Exploration Plan Drilling Company: Geologic Drill Bore Hole Dia.:6" Top Elevation: Approximately 26.5 FT Drilling Method: HAS Hammer Tme: Auto B-1 Date Drilled: 9/1112013 Drill Rig: Track Logged bv: RAR SOIL DESCRIPTION PENETRATION RESISTANCE (blowsKoot) E LU Standard Penetration Test o 0) a The stratification lines represent the approximate boundaries a a 2 m o Hammer Weight and Drop: U w between soil types. The transition maybe gradual. Refer to a ¢ c a 3 ar report text and appendices for additional information. 2 m 0 0 20 40 66 2 5 Pwith Medium dense, saturated, gray, medium to coarse GRAVEL I tsa s 21 some sand 50 ' SAMPLELEGEND GROUNDWATER LEGEND I2-inch O.D. split spoon sample f; Clean Sand 3-inch LD. Shelby tube sample Bentonite Grout/Concrete ® Screened Casing TESTING KEY ❑ Blank Casing GSA = Grain Size Analysis V Groundwater level at time of drilling (ATD) or 20OW = 200 Wash Analysis ? on date of Consol. = Consolidation Test measurement. Att. = Atterberg Limits 20 21 29 48 I:I i :ill I', . -fJ - - - ❑ - I II I Q °% Fines (<0.075 mm) O °% Water (Moisture) Content Plastic Limit Liquid Limit Natural Water Content Reserve at Renton 325 Rainer Ave. South Renton, WA Date: September, 2013 Project No.: 1187.01 Zipper Geo Associates BORING B_� 19023 36th Ave. W, Suite D LOG: Lynnwood, WA Page 2 of 3 Boring Location: See Figure 1, Site and Exploration Plan Drilling Company: Geologic Drill Bore Hale Dia.:6" Top Elevation: Approximately 26.5 FT Drilling Method: HAS Hammer Type: Auto B-1 Date Drilled: 911112013 Drill Rig: Track Logged by: RAR SOIL DESCRIPTION ` PENETRATION RESISTANCE (blowslfaol) a(0 e w m 3A N o Standard Penetration Test L CL The stratification lines represent the approximate boundaries z a- m d Hammer Weight and Drop: U �+ d between soil types. The transition maybe gradual. Refer to E <W C 3 report text and appendices for additional information. h o m 0 0 20 40 60 50 Dense, saturated, medium to coarse GRAVEL with some sand s t2 a',' iI� i.I �ii 47 t i Boring completed at 51.5 feet on 9-11-13. Groundwater observed at approximately 4.5 feet at time of drilling. 55 160 165 C 170 75 SAMPLE LEGEND GROUNDWATER LEGEND I2-inch O.D. split spoon sample Clean Sand 3-inch LD. Shelby tube sample Bentonite Grout/Concrete ® Screened Casing TESTING KEY U Blank Casing GSA = Grain Size Analysis ! Groundwater level at time of drilling (ATD) or 20OW = 200 Wash Analysis ? on date of Consol. = Consolidation Test N measurement. Aft. = Atterberg Limits l!iHil j''I Ii�', I'• it + j _._._1 I �Il i II II I I�lill ._I_1_ O % Fines (<0.075 mm) O % Water (Moisture) Content Plastic Limit i 8 d Liquid Limit Natural Water Content Reserve at Renton 325 Rainer Ave. South Renton, WA Date: September, 2013 Project No.: 1187.01 Zipper Geo Associates BORING Br,� 19023 36th Ave. W, Suite D LOG; Lynnwood, WA Page 3 of 3 Boring g Location: See Figure 1, Site and Exploration Plan Drillina Company: Geologic Drill Bore Hole Dia.: 6" Too Elevation- 28 FT Drilling Method: Hollow Stem Auger Hammer Type: Cat Head B-2 Date Drilled: 101212013 Drill Ria: Deep Rock XL Logged by_: JPC SOIL DESCRIPTION PENETRATION RESISTANCE (blawsiloot) J a o m ♦ Standard Penetration Test a The stratification lines represent the approximate boundaries II a 2 L Hammer Weight and Drop: U y a) between soil types. The transition may be gradual. Refer to e ¢ 3 3 w U report text and appendices for additional information. m 0 20 40 60 3.5 inches Asphalt concrete pavement over 8 inches crushed ------------------------------------- ,ravel - I ; I ' �ii I II IIIIII' Very loose, wet, gray -brown, silty SAND with trace gravel II l' �--r I ___________________________________________ 5 Soft, wet to saturated, gray, sandy SILT with trace peaty T II organics s-2 I 12' 5-3 12' Very loose, saturated, gray SAND with trace silt 10 grades to medium dense s-4 12" 1 Boring completed at 11.5 feet on 10/2113. Groundwater measured at 6.5 feet on 10110/13. 15 20 25 ' SAMPLE LEGEND GROUNDWATER LEGEND I2-inch O.D. split spoon sample Clean Sand 3-inch I.D. Shelby tube sample Bentonite Grout/Concrete ❑ Screened Casing TESTING KEY ❑ Blank Casing GSA = Grain Size Analysis Groundwater level at time of drilling (ATD) or 200W = 200 Wash Analysis a on date of Consul. = Consolidation Test N measurement. Att. = Atterberg Limits IIIII' `I Ir� 7 I I' ?- —Ii +! 'III! I I 1 k!T I I I III i - ' I I I I I 3 Tl i :I 1, 1111 II I I1111 I ' i 11 1 O % Fines (<0.075 mm) O % Water (Moisture) Content Plastic Limit Liquid Limit Natural Water Content Reserve at Renton 325 Rainer Ave. South Renton, WA Date: - Project No.: 1187.01 Zipper Geo Associates BORING B-2 19023 36th Ave. W, Suite D LOG: Lynnwood, WA Page 1 of 1 Boring Location: See Figure 1, Site and Exploration Plan Drilling Company: Geologic Drill Bore Hole Dia.:6" Top Elevation: 28 Drilling Method: Hollow Stem Auger Hammer Type: Cat Head B-3 Date Drilled: 10/2/2013 Drill Rig: Deep Rock XL Logged by: JPC SOIL DESCRIPTION PENETRATION RESISTANCE (blowslfoot) '.U) J Standard Penetration Test .. o m The stratification fines represent the approximate boundaries a z (L o 0 Hammer Weight and Drop: Q 0) between soil types. The transition may be gradual. Refer to E 3 ~ a report text and appendices for additional information. in 0) ° in (D 0 20 40 60 0 4 inches Asphalt concrete pavement over 8 inches crushed .gravel I ---------------------------------------- ' Very loose, wet gray, silty SAND "�-Y-}"%-I--,tom-I I S1 12" I : :: Iil �i I } 'I� 1 I' I I 4 Soft, wet to saturated, gray brown, sandy SILT with some l 5 peaty organics 52 12" 4 __________________________________________ �: rt- Very loose, saturated, gray, SAND with trace silt S3 T 12 _ w j� - j - 4 11 :.=.:.. ,-�I 10 ------------------------------------------- Medium dense, saturated, gray, gravelly SAND I I S4 12" 17 Boring completed at 11.5 feet on 1012l13. Groundwater measured at 6.6 feet on 10/10113. ill�ia+I+� 115 �j 120 25 ' SAMPLELEGEND GROUNDWATER LEGEND I2-inch 0. D. split spoon sample Clean Sand �3-inch 1.D. Shelby tube sample Bentonite Grout/Concrete ® Screened Casing TESTING KEY U Blank Casing GSA = Grain Size Analysis Z Groundwater level at time of drilling (ATD) or 20OW = 200 Wash Analysis 0 on date of Consol- = Consolidation Test ti measurement. Aft. = Atterberg Limits it �li,,�III� Illlil 4 °% Fines (<0.075 mm) Q °% Water (Moisture) Content Plastic Limit 1 8 1 Liquid Limit Natural Water Content Reserve at Renton 325 Rainier Ave. South Renton, WA Date: - Project No.: 1187,01 Zipper Geo Associates BORING B-3 19023 36th Ave. W, Suite D LOG; Lynnwood, WA Page 1 of 1 Depth (1f Tip Resistance Qt TSF 0 5 T� 10 15 20 25 30 Subsurface Technologies Operator: SAM CPT Date/Time: 1013/2013 11A4:42 AM Sounding: CPT-1 Location: RESERVE AT RENTON Cone Used: OSG0457 Job Number: 1187.01 Local Friction Friction Ratio Pore Pressure Diff PP Ratio Soil Behavior Type' Fs TSF Fs/Qt (%) Pw PSI (Pw-Ph)1Qt (%) Zone: UBC-1983 250 0 5 0 10 -20 100 -20 100 0 12 Maximum Depth = 25-26 feet 1 sensitive fine grained ■ 4 silty clay to clay ® 2 organic material 5 clayey silt to silty clay ■ 3 clay ■ 6 sandy silt to clayey sill 'Soil behavior type and SPT based on date from UBC-1983 Depth Increment = 0.328 feet ■ 7 silty sand to sandy silt ■ 10 gravelly sand to sand 8 sand to silly sand ® 11 very stiff fine grained (`) 9 sand ■ 12 sand to clayey sand (') Depth (t1) Tip Resistance QtTSF 0 0 T� 5 10 15 20 25 Subsurface Technologies Operator: SAM CPT Date/Time: 1013/2013 11:48:34 AM Sounding: CPT-2 Location: RESERVE AT RENTON Cone Used: DSG0457 Job Number: 1187,01 Friction Ratio Pore Pressure Fs/Qt (%) Pw PSI 0 10 -20 100 -60 1 I i I OOP II I, I II ;I I I II I � I I I 1 I I I I I I I I I I : I I I I 1 i t r I I I I I : I I I 1 I I I I I _ I I I I I Maximum Depth = 24.93 feet 1 sensitive fine grained / 4 silty clay to clay 2 organic material , 5 clayey sill to silty clay 03 clay 6 sandy silt to clayey silt 'Soil behavior type and SPT based on data from UBC-1983 jiff PP Ratio Soil Behavior Pw-Ph)/Qt (%) Zone: UBC-11 100 0 1 7T-FTT7[Tl-FFT[FF I I ,:'I I i I rill 1 i l 1 1 1 rl I I r I I I II 3 I I I lei I I r I I, III I I rllll ll Fll - I i I , tf II I'I lilll IIy�� ti I ja I 7�1 rd I I I i d-lsh�r,7;1 i t i I I.I !, IyIY f i r I 11'1.5.1 f-I i ll IIE-1 ililr Depth Increment = 0.328 feet 7 silty sand to sandy silt N10 gravelly sand to sand 8 sand to silty sand ■ 11 very stiff fine grained (") 9 sand 12 sand to clayey sand ( } Tip Resistance Qt TSF 0 6�111111111111 Subsurface Technologies Operator: SAM CPT DatelTime: 101312013 10:18:23 AM Sounding: CPT-3 Location: RESERVE AT RENTON Cane Used: DSG0457 Job Number: 1187.01 Local Friction Friction Ratio Pare Pressure Diff PP Ratio Soil Behavior Type* Fs TSF Fs/Qt (°%} Pw PSI (Pw-Ph)/Qt (%) Zone: UBC-1983 250 0 5 0 10 -20 100 -20 100 0 12 r---1'T7-7-1 :rImI iTi i i -l- rW 1 1 1 1 1 1 7 1 I I I i 10 r I I i I i i i 1 Depth , (ft) II I I 15 20 I i i I I i 11 i I I I I I I I 25 Maximum Depth = 24.93 feet 1 sensitive fine grained ■ 4 silty clay to day ■ 2 organic material ■ 5 clayey silt to silty clay ■ 3 clay ■ 6 sandy silt to clayey silt 'Soil behavior type and SPT based on data from UBC-1983 I ' I I ' I I I I I i I I I I II I 1 I I i i I ' I I I I I I I I I I I I I i I I . I II I I II i I Depth Incremen ■ 7 silty sand to sandy sil 8 sand to silty sand 9 sand 1 1 1 1 I i I I I I Il I I I I IIII I I I 111111 I i — - i.l III r I . . I r: ' 4 � ' II III III 11 t�i tt I r;i I I I� 1�4f r 1-1 - 1iE4EiF:li1 I : I'I.1 I I A ill -ICI ..A.JJ I O1,-I:'1 I - i lw.f:.:1:. It 1 1.. 1..1 I I:..I.:t I��.,-. i..-I., �1�3 I I.I i�l:l-i 4 I I I. I 999Yl = 0.328 feet i ■ 10 gravelly sand to ■ 11 very stiff fine grain ■ 12 sand to clayey sE sand ed (') nd (*) Depth (ft) Tip Resistance QtTSF 4 0 I —1- 5 10 W 20 25 Subsurface Technologies Operator: SAM CPT Date/Time: 101312013 10:18:23 AM Sounding: CPT-3 Location: RESERVE AT RENTON Cone Used: DSG0457 Job Number: 1187.01 Soil Behavior Type' Zone: UBC-1983 400 0 12 rTTIT- 1-TT�T-� 1 I I I I i I• f:l I %=a I rT "I IF. I I II I LMA . I C11 III, ;II1 I A 1 •irll ,ill I I rj _ I -I U r F1IAT 'a I I I I !1 Maximum Depth = 24.93 feet 1 sensitive fine grained ■ 4 silty clay to clay ■ 2 organic material ■ 5 clayey silt to silty clay ■ 3 day ■ 6 sandy silt to clayey silt 'Soil behavior type and SPT based on data from UBC-1983 SPT N` 60% Hammer 0 50 I � I I I I ■ 7 silty 8 sar 9 Seismic Delay (milliseconds) 0 60 Seismic Velocity (ft/s) 0 900 ,I�IIII lilll� � lilli � � I i , L.I , I i I ' 1399-15467 I f r 1 33.24 376.4764 I I 'I '141�29 I` 459,968i1 j 4 014 . . . . 88T6312 II � II I I I I i I Depth Increment = 0,328 feet ;and to sandy silt ■ 10 gravelly sand to sand td to silty sand ■ 11 very stiff fine grained (`) sand ■ 12 sand to clayey sand (') Subsurface Technologies Operator: SAKI CPT Date/Time: 10/3/2013 12:40:42 PM Sounding: CPT-4 Location: RESERVE AT RENTON Cone Used: DSG0457 Job Number: 1187.01 Friction Ratio Pore Pressure Diff PP Ratio Soil Behavior Type' Fs/Qt (°k) Pw PSI (Pw-Ph)IQt (%) Zone: UBC-1983 0 10 -20 100 -20 100 0 12 I I I , I -'�IIII�I I I I I I I l I�. III I LI I I i I I I I I I I I I I II l l 3 � I � III IIIIII i I I I I� IIII . , I I III IIIIII I � I I i ill il;l� ,� Ll lljfll� , I ilif:lll 'I � ' 11.".l•"� 9 4 j 3� t .I I kr€E_t+r�'LI I I I I I I I I I i I 1030 I I I I f 6��TIT 30 Maximum Depth = 28.54 feet 1 sensitive fine grained ■ 4 silty clay to clay ■ 2 organic material ■ 5 clayey silt to silty clay ■ 3 Gay ■ 6 sandy silt to clayey silt 'Soil behavior type and SPT based on data from UBC-1983 Depth Increment = 0.328 feet ■ 7 silty sand to sandy silt ■ 10 gravelly sand to sand 8 sand to silty sand ® 11 very stiff fine grained (') 9 sand ■ 12 sand to clayey sand (*j APPENDIX B LABORATORY TESTING PROCEDURES & RESULTS 1_1:J: 1110.1 LABORATORY TESTING PROCEDURES AND RESULTS A series of laboratory tests were performed by ZGA during the course of this study to evaluate the index and geotechnical engineering properties of the subsurface soils. Descriptions of the types of tests performed are given below. Visual Classification Samples recovered from the exploration locations were visually classified in the field during the exploration program. Representative portions of the samples were carefully packaged in moisture tight containers and transported to our laboratory where the field classifications were verified or modified as required. Visual classification was generally done in accordance with ASTM D2488. Visual soil classification includes evaluation of color, relative moisture content, soil type based upon grain size, and accessory soil types included in the sample. Soil classifications are presented on the exploration logs in Appendix A. Moisture Content Determinations Moisture content determinations were performed on representative samples obtained from the explorations in order to aid in identification and correlation of soil types. The determinations were made in general accordance with the test procedures described in ASTM D 2216. Moisture contents are presented on the exploration logs in Appendix A. C CM ENGINEERING TIR SECTION 7: OTHER PERMITS This project will need to obtain Site Plan, Building, and Construction permits from the City of Renton. In addition to permits required by the City of Renton, it will also be necessary to obtain a Construction Stormwater General Permit from the Department of Ecology. Technical Information Report RENTON CENTER SENIOR LIVING — Project #t13133.20 4=04M ENGINEERING TIR SECTION S: CSWPPP ANALYSIS AND DESIGN This section of the TIR is to provide a summary of erosion controls and source controls for the site. A full CSWPPP narrative meeting the Department of Ecology format and standards is provided in the following pages of this report_ Technical Information Report RENTON CENTER SENIOR LIVING —Project #13133.20 n Stormwater Pollution Prevention Plan Owner Christopher Santoro 3424 Via Oporto, Ste. 20 For Renton Center Senior Living Prepared For Northwest Regional Office 3190 - 160th Avenue SE Bellevue, WA 98008-5452 425-649-7000 Developer Christopher Santoro 3424 Via Oporto, Ste. 20 Operator/Contractor Exxel Pacific 323 Telegraph Road Newport Beach, CA 92663 Newport Beach, CA 92663 Bellingham, WA 98226 Project Site Location 625 Renton Center Way Certified Erosion and Sediment Control Lead SWPPP Prepared By CG Engineering 250 4`h Ave S, Suite 200 Edmonds, WA 425-778-8500 Contact: Jared Underbrink SWPPP Preparation Date October 2013 Approximate Project Construction Dates April 2014 April 2015 n Contents 1. 0 Introduction............................................................................................................................... I 2.0 Site Description........................................................................................................................3 2.1 Existing Conditions...........................................................................................................3 2.2 Proposed Construction Activities......................................................................................3 3.0 Construction Stormwater BMPs...............................................................................................5 3.1 The 12 BMP Elements.......................................................................................................5 3.1.1 Element # 1 — Mark Clearing Limits................................................................5 3.1.2 Element #2 — Establish Construction Access...................................................5 3.1.3 Element #3 — Control Flow Rates....................................................................6 3.1.4 Element #4 — Install Sediment Controls..........................................................6 3.1.5 Element #5 — Stabilize Soils............................................................................7 3.1.6 Element 06 — Protect Slopes............................................................................8 3.1.7 Element #7 — Protect Drain Inlets....................................................................9 3.1.8 Element#8 -- Stabilize Channels and Outlets..................................................9 3.1.9 Element #9 — Control Pollutants....................................................................10 3.1.10 Element # 10 — Control Dewatering...............................................................10 3.1.11 Element #11 — Maintain BMPs......................................................................15 3.1.12 Element # 12 -- Manage the Project................................................................15 3.2 Site Specific BMPs..........................................................................................................15 3.3 Additional Advanced 13MPs............................................................................................15 4.0 Construction Phasing and BMP Implementation...................................................................15 5.0 Pollution Prevention Team......................................................................................................17 5.1 Roles and Responsibilities..........................................................................................•....17 5.2 Team Members................................................................................................................18 6.0 Site Inspections and Monitoring.............................................................................................19 6.1 Site Inspection.................................................................................................................19 6.1.1 Site Inspection Frequency..............................................................................19 6.1.2 Site Inspection Documentation......................................................................20 6.2 Stormwater Quality Monitoring.....................................................................................20 6.2.1 Turbidity........................................................................................................20 6.2.2 pH...................................................................................................................21 7.0 Reporting and Recordkeeping................................................................................................23 7.1 Recordkeeping.................................................................................................................23 7.1.1 Site Log Book................................................................................................23 7.1.2 Records Retention..........................................................................................23 7.1.3 Access to Plans and Records..........................................................................23 I n 7.1.4 Updating the SWPPP.......................................... .................24 7.2 Reporting.................................................................................................... ..........24 7.2.1 Discharge Monitoring Reports.......................................................................24 7.2.2 Notification of Noncompliance......................................................................24 7.2.3 Permit Application and Changes...................................................................24 AppendixA — Site Plans.........................................................................................................25 Appendix B — Construction BMPs.........................................................................................28 Appendix C — Alternative BMPs............................................................................................29 AppendixD — General Permit................................................................................................31 Appendix E — Site Inspection Forms (and Site Log)..............................................................32 Appendix F — Engineering Calculations.................................................................................41 Appendix A Site plans ■ Vicinity map (with all discharge points) ■ Site plan with TESC measures Appendix B Construction BMPs ■ Possibly reference in BMPs, but likely it will be a consolidated list so that the applicant can photocopy from the list from the S WMM. Appendix C Alternative Construction BMP list ■ List of BMPs not selected, but can be referenced if needed in each of the 12 elements Appendix D General Permit Appendix E Site Log and Inspection Forms Appendix F Engineering Calculations Stormwater Pollution Prevention Plan 1.0 Introduction This Stormwater Pollution Prevention Plan (SWPPP) has been prepared as part of the NPDES stormwater permit requirements for the Reserve at Renton construction project in Renton, Washington. The site is located at 625 Renton Center Way. The existing site is a 3.67-acre lot with one paved parking lot and one gravel parking lot. The proposed development consists of the construction of a new senior apartment building complex that will include 219 units, a courtyard, and landscaping. Construction activities will include demolition, excavation, grading, relocation of onsite services/utilities, and construction of a 219-unit apartment building. The purpose of this SWPPP is to describe the proposed construction activities and all temporary and permanent erosion and sediment control (TESC) measures, pollution prevention measures, inspection/monitoring activities, and recordkeeping that will be implemented during the proposed construction project. The objectives of the SWPPP are to: Implement Best Management Practices (BMPs) to prevent erosion and sedimentation, and to identify, reduce, eliminate or prevent stormwater contamination and water pollution from construction activity. 2. Prevent violations of surface water quality, ground water quality, or sediment management standards. 3. Prevent, during the construction phase, adverse water quality impacts including impacts on beneficial uses of the receiving water by controlling peak flow rates and volumes of stormwater runoff at the Permittee's outfalls and downstream of the outfalls. This SWPPP was prepared using the Ecology SWPPP Template downloaded from the Ecology website on October 1, 2013, This SWPPP was prepared based on the requirements set forth in the Construction Stormwater General Permit, Stormwater Management Manual for Western Washington (SWMMWW 2005) and in the Stormwater Management Manual for Eastern Washington (SWMMEW 2004). The report is divided into seven main sections with several appendices that include stormwater related reference materials. The topics presented in the each of the main sections are: ■ Section I — INTRODUCTION. This section provides a summary description of the project, and the organization of the SWPPP document. ■ Section 2 -- SITE DESCRIPTION. This section provides a detailed description of the existing site conditions, proposed construction activities, and calculated stormwater flow rates for existing conditions and post — construction conditions. Stormwater Pollution Prevention Plan ■ Section 3 — CONSTRUCTION BMPs. This section provides a detailed description of the BMPs to be implemented based on the 12 required elements of the SWPPP (SWMMEW 2004). ■ Section 4 — CONSTRUCTION PHASING AND BMP IMPLEMENTATION. This section provides a description of the timing of the BMP implementation in relation to the project schedule. ■ Section 5 — POLLUTION PREVENTION TEAM. This section identifies the appropriate contact names (emergency and non -emergency), monitoring personnel, and the onsite temporary erosion and sedimentation control inspector ■ Section 6 -- INSPECTION AND MONITORING. This section provides a description of the inspection and monitoring requirements such as the parameters of concern to be monitored, sample locations, sample frequencies, and sampling methods for all Stormwater discharge locations from the site. Section 7 — RECORDKEEPING. This section describes the requirements for documentation of the BMP implementation, site inspections, monitoring results, and changes to the implementation of certain BMPs due to site factors experienced during construction. Supporting documentation and standard forms are provided in the following Appendices: Appendix A — Site plans Appendix B — Construction BMPs Appendix C — Alternative Construction BMP list Appendix D — General Permit Appendix E — Site Log and Inspection Forms Appendix F — Engineering Calculations z Stormwater Pollution Prevention Plan 2.0 Site Description 2.1 Existing Conditions The proposed site is located just off Renton Center Way and to the east of Hardie Ave SW in Renton, WA. A site vicinity map and coordinates are provided in Appendix A. The site is 3.67 acres in size and includes two developed parking areas. The eastern half of the site is a parking area which connects to the Renton Center parking. The western half is a less -used parking lot, and a significant portion of the area is gravel rather than pavement. The topography of the site and surrounding properties gently slopes to the west, with slopes ranging from 0.5% to 2.0%. Surficial soils primarily consist of outwash soils. The site has a high groundwater table, lies less than 5 feet below the surface and limits the use of some infiltration facilities. The site contains several catch basins to convey runoff from the site. The eastern half of the site drains into the storm system in the Fred Meyer parking lot to the north, while the western half of the site drains into the storm system on Hardie Ave SW. The city system discharges to the Black River. There are no critical areas on the site such as high erosion risk areas, wetlands, streams, or steep slopes (potential landslide area). The proposed project is in a peak rate flow control standard zone, meaning that the existing condition can be used in the stormwater calculations (for most sites is necessary to consider the existing condition a forested condition in the stormwater modeling). Because this site actually decreases the amount of impervious areas, the peak flow control rates are lessened, and a large detention or infiltration system is not necessary. This is summarized in greater detail in future chapters of this report. 2.2 Proposed Construction Activities The proposed development includes the construction of a 219-unit senior apartment building and its associated parking, driveways, courtyards, and utilities. The proposed building will be located on the western half site, adjacent to Hardie Ave SW. The eastern parking lot will be overlayed and runoff from that portion of the site will drain into the storm system for the Fred Meyer parking lot. The eastern half of the site will be tied into the Hardie Ave SW storm sewer. Construction activities will include site preparation, TESC installation, demolition of existing pavement, excavation for the building foundations, poured concrete foundations, concrete tilt -up Stormwater Pollution Prevention Plan building construction, site -wide grading, and asphalt paving. The schedule and phasing of BMPs during construction is provided in Section 4.0. Stormwater runoff volumes were calculated using the King County Runoff Time Series (KCRTS). The temporary sedimentation pond that will be used during construction was designed using the 2-year storm event since construction will not occur over a long time -frame (approximately one year). The pre- and post -construction peak flows were compared using the 2, 10, and 100 year storm events. Conveyance systems were designed using the 25 year storm. After the building is constructed and all new utilities are installed, the site will be graded and paved. The following summarizes details regarding site areas: ■ Total site area: 3.67 acres ■ Percent impervious area before construction: 86 % ■ Percent impervious area after construction: 75 % ■ Disturbed area during construction: 2.07 acres ■ Disturbed area that is characterized as impervious (i.e., access roads, staging, parking): 1.54 acres ■ 2-year stormwater runoff peak flow prior to construction (existing): 0.79 cfs ■ 10-year stormwater runoff peak flow prior to construction (existing): 0.93 cfs ■ 2-year stormwater runoff peak flow during construction: 0.73 efs ■ 10-year stormwater runoff peak flow during construction: 0.88 efs ■ 2-year stormwater runoff peak flow after construction: 0.73 cfs ■ 10-year stormwater runoff peak flow after construction: 0.88 cfs All stormwater flow calculations are provided in Appendix F. 4 Stormwater Pollution Prevention Plan 3.0 Construction Stormwater BMPs 3.1 The 12 BMP Elements 3.1.1 Element #1 —Mark Clearing Limits To protect adjacent properties and to reduce the area of soil exposed to construction, the limits of construction will be clearly marked before land -disturbing activities begin. Trees that are to be preserved, as well as all sensitive areas and their buffers, shall be clearly delineated, both in the field and on the plans. In general, natural vegetation and native topsoil shall be retained in an undisturbed state to the maximum extent possible. The BMPs relevant to marking the clearing limits that will be applied for this project include: High Visibility Plastic or Metal Fence (BMP C 103) Clearing limits will be marked with a high visibility fence as shown on the C2.1 plan in the civil drawings. Alternate BMPs for marking clearing limits are included in Appendix C as a quick reference tool for the onsite inspector in the event the BMP(s) listed above are deemed ineffective or inappropriate during construction to satisfy the requirements set forth in the General NPDES Permit (Appendix D). To avoid potential erosion and sediment control issues that may cause a violation(s) of the NPDES Construction Stormwater permit (as provided in Appendix D), the Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or more of the alternative BMPs listed in Appendix C after the first sign that existing BMPs are ineffective or failing. 3.1.2 Element #2 — Establish Construction Access Construction access or activities occurring on unpaved areas shall be minimized, yet where necessary, access points shall be stabilized to minimize the tracking of sediment onto public roads, and wheel washing, street sweeping, and street cleaning shall be employed to prevent sediment from entering state waters. All wash wastewater shall be controlled on site. The specific BMPs related to establishing construction access that will be used on this project include: Stabilized Construction Entrance (BMP C 105) A stabilized construction entrance will be added at the western edge of the site, and will help to prevent sediment tracking into the right of way. Stormwater Pollution Prevention Plan Alternate construction access BMPs are included in Appendix C as a quick reference tool for the onsite inspector in the event the BMP(s) listed above are deemed ineffective or inappropriate during construction to satisfy the requirements set forth in the General NPDES Permit (Appendix D). To avoid potential erosion and sediment control issues that may cause a violation(s) of the NPDES Construction Stormwater permit (as provided in Appendix D), the Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or more of the alternative BMPs listed in Appendix C after the first sign that existing BMPs are ineffective or failing. 3.1.3 Element #3 — Control Flow Rates In order to protect the properties and waterways downstream of the project site, Stormwater discharges from the site will be controlled. The specific BMPs for flow control that shall be used on this project include: Sediment Trap (BMP C240) The sediment trap will be located at the western edge of the site, near Hardie Ave SW. Sizing calculations are provided in Appendix F Alternate flow control BMPs are included in Appendix C as a quick reference tool for the onsite inspector in the event the BMP(s) listed above are deemed ineffective or inappropriate during construction to satisfy the requirements set forth in the General NPDES Permit (Appendix D). To avoid potential erosion and sediment control issues that may cause a violation(s) of the NPDES Construction Stormwater permit (as provided in Appendix D), the Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or more of the alternative BMPs listed in Appendix C after the first sign that existing BMPs are ineffective or failing. In general, discharge rates of stormwater from the site will be controlled where increases in impervious area or soil compaction during construction could lead to downstream erosion, or where necessary to meet local agency stormwater discharge requirements (e.g. discharge to combined sewer systems). 3.1.4 Element #4 — Install Sediment Controls All stormwater runoff from disturbed areas shall pass through an appropriate sediment removal BMP before leaving the construction site or prior to being discharged to an infiltration facility. The specific BMPs to be used for controlling sediment on this project include: Silt Fence (BMP C233) Sediment Trap (BMP C240) Soormwater Pollution Prevention Plan A silt fence will be installed around the downhill perimeter of the site as shown on the C2.1 Plan. The sediment trap will be installed as indicated in Element 43's description. Alternate sediment control BMPs are included in Appendix C as a quick reference tool for the onsite inspector in the event the BMP(s) listed above are deemed ineffective or inappropriate during construction to satisfy the requirements set forth in the General NPDES Permit (Appendix D). To avoid potential erosion and sediment control issues that may cause a violation(s) of the NPDES Construction Stormwater permit (as provided in Appendix D), the Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or more of the alternative BMPs listed in Appendix C after the first sign that existing BMPs are ineffective or failing. In addition, sediment will be removed from paved areas in and adjacent to construction work areas manually or using mechanical sweepers, as needed, to minimize tracking of sediments on vehicle tires away from the site and to minimize washoff of sediments from adjacent streets in runoff. Whenever possible, sediment laden water shall be discharged into onsite, relatively level, vegetated areas (BMP C240 paragraph 5, page 4-102). In some cases, sediment discharge in concentrated runoff can be controlled using permanent stormwater BMPs (e.g., infiltration swales, ponds, trenches). Sediment loads can limit the effectiveness of some permanent stormwater BMPs, such as those used for infiltration or biofiltration; however, those BMPs designed to remove solids by settling (wet ponds or detention ponds) can be used during the construction phase. When permanent stormwater BMPs will be used to control sediment discharge during construction, the structure will be protected from excessive sedimentation with adequate erosion and sediment control BMPs. Any accumulated sediment shall be removed after construction is complete and the permanent stormwater BMP will be restabilized with vegetation per applicable design requirements once the remainder of the site has been stabilized. 3.1.5 Element #5 — Stabilize Soils Exposed and unworked soils shall be stabilized with the application of effective BMPs to prevent erosion throughout the life of the project. The specific BMPs for soil stabilization that shall be used on this project include: Temporary and Permanent Seeding (BMP C120) Dust Control (BMP C 140) 7 5tormwater Pollution Prevention Plan The ESC Supervisor shall be familiar with BMPs for soil stabilization and dust control and implement these BMPs where needed on the proposed site. Alternate soil stabilization BMPs are included in Appendix C as a quick reference tool for the onsite inspector in the event the BMP(s) listed above are deemed ineffective or inappropriate during construction to satisfy the requirements set forth in the General NPDES Permit (Appendix D). To avoid potential erosion and sediment control issues that may cause a violation(s) of the NPDES Construction Stormwater permit (as provided in Appendix D), the Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or more of the alternative BMPs listed in Appendix C after the first sign that existing BMPs are ineffective or failing. The project site is located west of the Cascade Mountain Crest. As such, no siols shall remain exposed and unworked for more than 7 days during the dry season (May 1 to September 30) and 2 days during the wet season (October 1 to April 30). Regardless of the time of year, all soils shall be stabilized at the end of the shift before a holiday or weekend if needed based on weather forecasts. In general, cut and fill slopes will be stabilized as soon as possible and soil stockpiles will be temporarily covered with plastic sheeting. All stockpiled soils shall be stabilized from erosion, protected with sediment trapping measures, and where possible, be located away from storm drain inlets, waterways, and drainage channels. 3.1.6 Element #6 — Protect Slopes All cut and fill slopes will be designed, constructed, and protected in a manner than minimizes erosion. The following specific BMPs will be used to protect slopes for this project: Temporary and Permanent Seeding (BMP C120) Interceptor Dike and Swale (BMP C200) Check Dams (BMP C207) Interceptor Swales with check dams are shown on the C2.1 plan to show the contractor how to direct flows to the sediment trap during contract. These facilities should be relocated as warranted during construction. Alternate slope protection BMPs are included in Appendix C as a quick reference tool for the onsite inspector in the event the BMP(s) listed above are deemed ineffective or inappropriate during construction to satisfy the requirements set forth in the General NPDES Permit (Appendix D). To avoid potential erosion and sediment control issues that may cause a violation(s) of the Stormwater Pollution Prevention Plan NPDES Construction Stormwater permit (as provided in Appendix D), the Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or more of the alternative BMPs listed in Appendix C after the first sign that existing BMPs are ineffective or failing. 3.1.7 Element #7 — Protect Drain inlets All storm drain inlets and culverts made operable during construction shall be protected to prevent unfiltered or untreated water from entering the drainage conveyance system. However, the first priority is to keep all access roads clean of sediment and keep street wash water separate from entering storm drains until treatment can be provided. Storm Drain Inlet Protection (BMP C220) will be implemented for all drainage inlets and culverts that could potentially be impacted by sediment -laden runoff on and near the project site. The following inlet protection measures will be applied on this project: Drop Inlet Protection Excavated Drop Inlet Protection Block and Gravel Drop Inlet Protection • Gravel and Wire Drop Inlet Protection • Catch Basin Filters Alternative BMP not included in the SWMMWW (2005) or SWMMEW (2004) Inlet protection should be provided as shown on the C2.1 Plan. If the BMP options listed above are deemed ineffective or inappropriate during construction to satisfy the requirements set forth in the General NPDES Permit (Appendix D), or if no BMPs are listed above but deemed necessary during construction, the Certified Erosion and Sediment Control Lead shall implement one or more of the alternative BMP inlet protection options listed in Appendix C. 3.1.8 Element #8 — Stabilize Channels and Outlets Where site runoff is to be conveyed in channels, or discharged to a stream or some other natural drainage point, efforts will be taken to prevent downstream erosion. The specific BMPs for channel and outlet stabilization that shall be used on this project include: No BMPs to be implemented 5tormwater Pollution Prevention Plan Alternate channel and outlet stabilization BMPs are included in Appendix C as a quick reference tool for the onsite inspector in the event the BMP(s) listed above are deemed ineffective or inappropriate during construction to satisfy the requirements set forth in the General NPDES Permit (Appendix D). To avoid potential erosion and sediment control issues that may cause a violations) of the NPDES Construction Stormwater permit (as provided in Appendix D), the Certified Erosion and Sediment Control Lead will promptly initiate the implementation of one or more of the alternative BMPs listed in Appendix C after the first sign that existing BMPs are ineffective or failing. The project site is located west of the Cascade Mountain Crest. As such, all temporary on -site conveyance channels shall be designed, constructed, and stabilized to prevent erosion from the expected peak 10 minute velocity of flow from a Type 1A, 10-year, 24-hour recurrence interval storm for the developed condition. Alternatively, the 10-year, 1-hour peak flow rate indicated by an approved continuous runoff simulation model, increased by a factor of 1.6, shall be used. Stabilization, including armoring material, adequate to prevent erosion of outlets, adjacent streambanks, slopes, and downstream reaches shall be provided at the outlets of all conveyance systems. 3.1.9 Element #9 — Control Pollutants All pollutants, including waste materials and demolition debris, that occur onsite shall be handled and disposed of in a manner that does not cause contamination of stormwater. Good housekeeping and preventative measures will be taken to ensure that the site will be kept clean, well organized, and free of debris. If required, BMPs to be implemented to control specific sources of pollutants are discussed below. Sanitary wastewater: Portable sanitation facilities will be firmly secured, regularly maintained, and emptied when necessary. Wheel wash or tire bath wastewater shall be discharged to a separate on =site treatment system or to the sanitary sewer as part of Wheel Wash implementation (BMP C106) The facility does not require a Spill Prevention, Control, and Countermeasure (SPCC) Plan under the Federal regulations of the Clean Water Act (CWA). 3.1.10 Element #10 — Control Dewatering There will be no dewatering as part of this construction project. m 5tormwater Pollution Prevention Plan 3.1.11 Element #11 —Maintain BMPs All temporary and permanent erosion and sediment control BMPs shall be maintained and repaired as needed to assure continued performance of their intended function. Maintenance and repair shall be conducted in accordance with each particular BMPs specifications (attached). Visual monitoring of the BMPs will be conducted at least once every calendar week and within 24 hours of any stormwater or non-stormwater discharge from the site. If the site becomes inactive, and is temporarily stabilized, the inspection frequency will be reduced to once every month. All temporary erosion and sediment control BMPs shall be removed. within 30 days after the final site stabilization is achieved or after the temporary BMPs are no longer needed. Trapped sediment shall be removed or stabilized on site. Disturbed soil resulting from removal of BMPs or vegetation shall be permanently stabilized. 3.1.12 Element #12 — Manage the Project Erosion and sediment control BMPs for this project have been designed based on the following principles: ■ Design the project to fit the existing topography, soils, and drainage patterns. ■ Emphasize erosion control rather than sediment control. ■ Minimize the extent and duration of the area exposed. ■ Keep runoff velocities low. ■ Retain sediment on site. ■ Thoroughly monitor site and maintain all ESC measures. ■ Schedule major earthwork during the dry season. In addition, project management will incorporate the key components listed below: As this project site is located west of the Cascade Mountain Crest, the project will be managed according to the following key project components: Phasing of Construction The construction project is being phased to the extent practicable in order to prevent soil erosion, and, to the maximum extent possible, the transport of sediment from the site during construction. 11 5tormwater Pollution Prevention Plan Revegetation of exposed areas and maintenance of that vegetation shall be an integral part of the clearing activities during each phase of construction, per the Scheduling BMP (C 162). Seasonal Work Limitations From October 1 through April 30, clearing, grading, and other soil disturbing activities shall only be permitted if shown to the satisfaction of the local permitting authority that silt -laden runoff will be prevented from leaving the site through a combination of the following: ❑ Site conditions including existing vegetative coverage, slope, soil type, and proximity to receiving waters; and ❑ Limitations on activities and the extent of disturbed areas; and ❑ Proposed erosion and sediment control measures. ■ Based on the information provided and/or local weather conditions, the local permitting authority may expand or restrict the seasonal limitation on site disturbance. ■ The following activities are exempt from the seasonal clearing and grading limitations: ❑ Routine maintenance and necessary repair of erosion and sediment control BMPs; ❑ Routine maintenance of public facilities or existing utility structures that do not expose the soil or result in the removal of the vegetative cover to soil; and ❑ Activities where there is 100 percent infiltration of surface water runoff within the site in approved and installed erosion and sediment control facilities. Coordination with Utilities and Other Jurisdictions Care has been taken to coordinate with utilities, other construction projects, and the local jurisdiction in preparing this SWPPP and scheduling the construction work. 12 Stormwater Pollution Prevention Plan Inspection and Monitoring All BMPs shall be inspected, maintained, and repaired as needed to assure continued performance of their intended function. Site inspections shall be conducted by a person who is knowledgeable in the principles and practices of erosion and sediment control. This person has the necessary skills to: ❑ Assess the site conditions and construction activities that could impact the quality of stormwater, and ❑ Assess the effectiveness of erosion and sediment control measures used to control the quality of stormwater discharges. A Certified Erosion and Sediment Control Lead shall be on -site or on -call at all times. Whenever inspection and/or monitoring reveals that the BMPs identified in this SWPPP are inadequate, due to the actual discharge of or potential to discharge a significant amount of any pollutant, appropriate BMPs or design changes shall be implemented as soon as possible. Maintaining an Updated Construction SWPPP ■ This SWPPP shall be retained on -site or within reasonable access to the site. ■ The SWPPP shall be modified whenever there is a change in the design, construction, operation, or maintenance at the construction site that has, or could have, a significant effect on the discharge of pollutants to waters of the state. ■ The SWPPP shall be modified if, during inspections or investigations conducted by the owner/operator, or the applicable local or state regulatory authority, it is determined that the SWPPP is ineffective in eliminating or significantly minimizing pollutants in stormwater discharges from the site. The SWPPP shall be modified as necessary to include additional or modified BMPs designed to correct problems identified. Revisions to the SWPPP shall be completed within seven (7) days following the inspection. --- 13 Stormwater Pollution Prevention Plan 3.2 Site Specific BMPs Site specific BMPs are shown on the TESC Plan Sheets and Details in Appendix A. These site specific plan sheets will be updated annually. 3.3 Additional Advanced BMPs The following BMPs are advanced and are only recommended if construction activities are complex enough to warrant them, or if the site has the potential for significant impacts to water quality. The following BMPs are directed at "end of pipe" treatment for sedimentation issues related to turbid runoff from construction sites. Effective BMPs are most often the simple BMPs, and focus on the minimization of erosion before sedimentation is an issue. The following BMPs will most likely be implemented only after other BMP options are exhausted or if the construction activity is large and off site sedimentation or turbid runoff occurs or is inevitable. For BMP 250 written pre -approval through Ecology is required. Construction Stormwater Chemical Treatment (BMP C250) Construction Stormwater Filtration (BMP C251) 14 Stormwater Pollution Prevention Plan 4.0 Construction Phasing and BMP Implementation The BMP implementation schedule is driven by the construction schedule. The following provides a sequential list of the proposed construction schedule milestones and the corresponding BMP implementation schedule. The list contains key milestones such as wet season construction. BMP implementation schedule listed below is keyed to proposed phases of the construction project, and reflects differences in BMP installations and inspections that relate to wet season construction. The project site is located west of the Cascade Mountain Crest. As such, the dry season is considered to be from May 1 to September 30 and the wet season is considered to be from October I to April 30. The BMP implementation schedule is driven by the construction schedule. The following provides a sequential list of the proposed construction schedule milestones and the corresponding BMP implementation schedule. The list contains key milestones such as wet season construction. BMP implementation schedule listed below is keyed to proposed phases of the construction project, and reflects differences in BMP installations and inspections that relate to wet season construction. The project site is located west of the Cascade Mountain Crest. As such, the dry season is considered to be from May I to September 30 and the wet season is considered to be from October 1 to April 30. ■ Estimate of Construction start date: 04 / 01 / 2014 ■ Estimate of Construction finish date: 04 / 30 / 2015 ■ Mobilize equipment on site: 04 / 05 / 2014 ■ Mobilize and store all ESC and soil stabilization products (store materials on hand BMP C 150): 04 / 10 / 2014 ■ Install ESC measures: 04 / 10 / 2014 ■ Install stabilized construction entrance: 04 / 15 / 2014 ■ Begin clearing and grubbing: 04 / 20 / 2014 ■ Demolish existing pavement: 04 / 21 / 2014 15 Stormwater Pollution Prevention Plan Excavation for building foundations 04 / 30 / 2014 Soil stabilization on excavated sideslopes (in idle, no work areas as shown on ESC plans) 04 ! 30 / 2014 Dry Season starts: 05 / 01 / 2014 Temporary erosion control measures (hydroseeding) 05 / 10 / 2014 Excavate and install new utilities and service: 05 / 15 / 2014 Begin building construction: 05 / 20 / 2014 Complete utility construction: 07 / 31 / 2014 Site grading begins: 08 / 15 / 2014 Wet Season starts: 10 / 01 / 2014 Site grading ends: 10 / 21 / 2014 Final landscaping and planting begins: 01 / 07 / 2015 Permanent erosion control measures (hydroseeding): 02 / 15 / 2015 Building construction complete: 03 / 01 / 2015 Site Construction Complete: 04 / 30 / 2015 In Stormwater Pollution Prevention Plan 5.0 Pollution Prevention Team 5.1 Roles and Responsibilities The pollution prevention team consists of personnel responsible for implementation of the SWPPP, including the following: Certified Erosion and Sediment Control Lead (CESCL) — primary contractor contact, responsible for site inspections (BMPs, visual monitoring, sampling, etc.); to be called upon in case of failure of any ESC measures. Resident Engineer — For projects with engineered structures only (sediment ponds/traps, sand filters, etc.): site representative for the owner that is the project's supervising engineer responsible for inspections and issuing instructions and drawings to the contractor's site supervisor or representative ■ Emergency Ecology Contact — individual to be contacted at Ecology in case of emergency. ■ Emergency Owner Contact — individual that is the site owner or representative of the site owner to be contacted in the case of an emergency. ■ Non -Emergency Ecology Contact — individual that is the site owner or representative of the site owner than can be contacted if required. ■ Monitoring Personnel — personnel responsible for conducting water quality monitoring; for most sites this person is also the Certified Erosion and Sediment Control Lead. 17 Stormwater Pollution Prevention Plan 5.2 Team Members Names and contact information for those identified as members of the pollution prevention team are provided in the following table. Title Name(s) Certified Erosion and Sediment Control Lead (CESCL) T3 Meltema Resident Engineer Emergency Ecology Contact Emergency Owner Contact Non -Emergency Ecology Contact Monitoring Personnel CG Engineering Shawn Hopkins Chris Santoro CG Engineering Exxel Pacific Phone Number 360-734-2872 425-778-8500 425-649-7000 949-715-7099 425-778-8500 360-734-2872 18 Stormwater Pollution Prevention Plan 6.0 Site Inspections and Monitoring Monitoring includes visual inspection, monitoring for water quality parameters of concern, and documentation of the inspection and monitoring findings in a site log book. A site log book will be maintained for all on -site construction activities and will include: ■ A record of the implementation of the SWPPP and other permit requirements; Site inspections; and, Stormwater quality monitoring. For convenience, the inspection form and water quality monitoring forms included in this SWPPP include the required information for the site log book. This SWPPP may function as the site log book if desired, or the forms may be separated and included in a separate site log book. However, if separated, the site log book but must be maintained on -site or within reasonable access to the site and be made available upon request to Ecology or the local jurisdiction. 6.1 Site Inspection All BMPs will be inspected, maintained, and repaired as needed to assure continued performance of their intended function. The inspector will be a Certified Erosion and Sediment Control Lead (CESCL) per BMP C160. The name and contact information for the CESCL is provided in Section 5 of this SWPPP. Site inspection will occur in all areas disturbed by construction activities and at all Stormwater discharge points. Stormwater will be examined for the presence of suspended sediment, turbidity, discoloration, and oily sheen. The site inspector will evaluate and document the effectiveness of the installed BMPs and determine if it is necessary to repair or replace any of the BMPs to improve the quality of stormwater discharges. All maintenance and repairs will be documented in the site log book or forms provided in this document. All new BMPs or design changes will be documented in the SWPPP as soon as possible. 6.1.1 Site Inspection Frequency Site inspections will be conducted at least once a week and within 24 hours following any discharge from the site. For sites with temporary stabilization measures, the site inspection frequency can be reduced to once every month. 19 Stormwater Pollution Prevention Plan 6.1.2 Site Inspection Documentation The site inspector will record each site inspection using the site log inspection forms provided in Appendix E. The site inspection log forms may be separated from this SWPPP document, but will be maintained on -site or within reasonable access to the site and be made available upon request to Ecology or the local jurisdiction. 6.2 Stormwater Quality Monitoring 6.2.1 Turbidity Monitoring requirements for the proposed project will include either turbidity or water transparency sampling to monitor site discharges for water quality compliance with the 2005 Construction Stormwater General Permit (Appendix D). Sampling will be conducted at all discharge points at least once per calendar week. Turbidity or transparency monitoring will follow the analytical methodologies described in Section S4 of the 2005 Construction Stormwater General Permit (Appendix D). The key benchmark values that require action are 25 NTU for turbidity (equivalent to 32 cm transparency) and 250 NTU for turbidity (equivalent to 6 cm transparency). If the 25 NTU benchmark for turbidity (equivalent to 32 cm transparency) is exceeded, the following steps will be conducted 1. Ensure all BMPs specified in this SWPPP are installed and functioning as intended. 2. Assess whether additional BMPs should be implemented, and document modified BMPs in the SWPPP as necessary. 3. Sample discharge daily until the discharge is 25 NTU or lower. If the turbidity is greater than 25 NTU (or transparency is less than 32 cm) but less than 250 NTU (transparency greater than 6 cm) for more than 3 days, additional treatment BMPs will be implemented within 24 hours of the third consecutive sample that exceeded the benchmark value. Additional treatment BMPs to be considered will include, but are not limited to, off -site treatment, infiltration, filtration, and chemical treatment. If the 250 NTU benchmark for turbidity (or less than 6 cm transparency) is exceeded at any time, the following steps will be conducted: Notify Ecology by phone within 24 hours of analysis {see Section 5.0 of this SWPPP for contact information). 20 Stormwater Pollution Prevention Plan 2. Continue daily sampling until the turbidity is less than 25 NTU (or transparency is greater than 32 cm) 3. Initiate additional treatment BMPs such as off -site treatment, infiltration, filtration and chemical treatment within 24 hours of the first 250 NTU exceedance. 4. Implement additional treatment BMPs as soon as possible, but within 7 days of the first 250 NTU exceedance. 5. Describe inspection results and remedial actions taken in the site log book and in monthly discharge monitoring reports as described in Section 7.0 of this SWPPP. 6.2.2 pH Stormwater runoff will be monitored for pH starting on the first day of any activity that includes more than 40 yards of poured or recycled concrete, or after the application of "Engineered Soils" such as, Portland cement treated base, cement kiln dust, or fly ash. This does no include fertilizers. For engineered soils, the pH monitoring period begins when engineered soils are first exposed to precipitation and continue until the area is fully stabilized. Stormwater samples will be collected daily from all points of discharge from the site and measured for pH using a calibrated pH meter, pH test kit, or wide range pH indicator paper. If the measured pH is 8.5 or greater, the following steps will be conducted: 1. Prevent the high pH water from entering storm drains or surface water. 2. Adjust or neutralize the high pH water if necessary using appropriate technology such as CO2 sparging (liquid or dry ice). 3. Contact Ecology if chemical treatment other than CO2 sparging is planned. Sampling and monitoring for pH will occur during the phase of construction when concrete pouring will be conducted until fully cured (3 weeks from last pour) and discharges are documented to be below pH 8.5. Samples will be collected weekly at the sedimentation pond prior to discharge to surface water. Samples will be analyzed for pH using a calibrated pH meter and recorded in the site log book. The key benchmark pH value for stormwater is a maximum of 8.5. if a pH greater than 8.5 is measured in the sedimentation trap/pond(s) that has the potential to discharge to surface water, the following steps will be conducted: 21 Stormwater Pollution Prevention Plan Prevent (detain) all discharges from leaving the site and entering surface waters or storm drains if the pH is greater than 8.5 2. Implement CO2 sparging or dry ice treatment in accordance with Ecology BMP C252. Describe inspection results and remedial actions that are taken in the site log book and in monthly discharge monitoring reports as described in Section 7.0 of this SWPPP. 22 Stormwater Pollution Prevention Plan 7.0 Reporting and Recordkeeping 7.1 Recordkeeping 7.1.1 Site Log Book A site log book will be maintained for all on -site construction activities and will include: ■ A record of the implementation of the SWPPP and other permit requirements; ■ Site inspections; and, ■ Stormwater quality monitoring. For convenience, the inspection form and water quality monitoring forms included in this SWPPP include the required information for the site log book. This log book may be attached to this SWPPP if desired b the ESC Supervisor, but it is recommended that a separate binder be kept due to the approximately year long duration of the proposed construction. 7.1.2 Records Retention Records of all monitoring information (site log book, inspection reports/checklists, etc.), this Stormwater Pollution Prevention Plan, and any other documentation of compliance with permit requirements will be retained during the life of the construction project and for a minimum of three years following the termination of permit coverage in accordance with permit condition S5.C. 7.1.3 Access to Plans and Records The SWPPP, General Permit, Notice of Authorization letter, and Site Log Book will be retained on site or within reasonable access to the site and will be made immediately available upon request to Ecology or the local jurisdiction. A copy of this SWPPP will be provided to Ecology within 14 days of receipt of a written request for the SWPPP from Ecology. Any other information requested by Ecology will be submitted within a reasonable time. A copy of the SWPPP or access to the SWPPP will be provided to the public when requested in writing in accordance with permit condition S5.G. 23 Stormwater Pollution Prevention Plan 7.1.4 Updating the SWPPP In accordance with Conditions S3, S4.13, and S9.13.3 of the General Permit, this SWPPP will be modified if the SWPPP is ineffective in eliminating or significantly minimizing pollutants in stormwater discharges from the site or there has been a change in design, construction, operation, or maintenance at the site that has a significant effect on the discharge, or potential for discharge, of pollutants to the waters of the State. The SWPPP will be modified within seven days of determination based on inspection(s) that additional or modified BMPs are necessary to correct problems identified, and an updated timeline for BMP implementation will be prepared. 7.2 Reporting 7.2.1 Discharge Monitoring Reports If cumulative soil disturbance is 5 acres or larger: Discharge Monitoring Reports (DMRs) will be submitted to Ecology monthly. Of there was no discharge during a given monitoring period, the Permittee shall submit the form as required, with the words "No discharge" entered in the place of monitoring results. The DMR due date is 15 days following the end of each month. 7.2.2 Notification of Noncompliance If any of the terms and conditions of the permit are not met, and it causes a threat to human health or the environment, the following steps will be taken in accordance with permit section S5.F: Ecology will be immediately notified of the failure to comply. 2. Immediate action will be taken to control the noncompliance issue and to correct the problem. If applicable, sampling and analysis of any noncompliance will be repeated immediately and the results submitted to Ecology within five (5) days of becoming aware of the violation. 3. A detailed written report describing the noncompliance will be submitted to Ecology within five (5) days, unless requested earlier by Ecology. 7.2.3 Permit Application and Changes In accordance with permit condition S2.A, a complete application form will be submitted to Ecology and the appropriate local jurisdiction (if applicable) to be covered by the General Permit. 24 Stormwater Pollution Prevention Plan Appendix A — Site Plans 25 Q L rr w� x ENGINEERING 2504th Ave South Suite 00 Edmonds, 1 "a� N o W m o F �— W NVId IOSIN00 NOIS083 A21YHOdAR rM NOMS AMa31N3O NO1NM SiZ9 NOIN38 IV MUM 3HL r a Ko�a�s�o 31ro C ' rP L LO Stormwater Pollution Prevention Plan Appendix B — Construction BMPs High Visibility Plastic or Metal Fence (BMP C103) Stabilized Construction Entrance (BMP C 105) Sediment Trap (BMP C240) Silt Fence (BMP C233) Temporary and Permanent Seeding (BMP C120) Dust Control (BMP C 140) Interceptor Dike and Swale (BMP C200) Check Dams (BMP C207) 28 Stormwater Pollution Prevention Plan Appendix C — Alternative BMPs The following includes a list of possible alternative BMPs for each of the 12 elements not described in the main SWPPP text. This list can be referenced in the event a BMP for a specific element is not functioning as designed and an alternative BMP needs to be implemented. Element 91 - Mark Clearing Limits Element #2 - Establish Construction Access Element #3 - Control Flow Rates Element #4 - Install Sediment Controls Advanced BMPs: Element #5 - Stabilize Soils Element #6 - Protect Slopes Element #S - Stabilize Channels and Outlets Element #10 - Control Dewatering Additional Advanced BMPs to Control Dewatering: 29 Stormwater Pollution Prevention Plan Appendix D — General Permit 31 Stormwater Pollution Prevention Plan Appendix E — Site Inspection Forms (and Site Log) The results of each inspection shall be summarized in an inspection report or checklist that is entered into or attached to the site log book. It is suggested that the inspection report or checklist be included in this appendix to keep monitoring and inspection information in one document, but this is optional. However, it is mandatory that this S WPPP and the site inspection forms be kept onsite at all times during construction, and that inspections be performed and documented as outlined below. At a minimum, each inspection report or checklist shall include: a. Inspection date/times b. Weather information: general conditions during inspection, approximate amount of precipitation since the last inspection, and approximate amount of precipitation within the last 24 hours. C. A summary or list of all BMPs that have been implemented, including observations of all erosion/sediment control structures or practices. d. The following shall be noted: i. locations of BMPs inspected, ii. locations of BMPs that need maintenance, iii. the reason maintenance is needed, iv. locations of BMPs that failed to operate as designed or intended, and V. locations where additional or different BMPs are needed, and the reason(s) why e. A description of stormwater discharged from the site. The presence of suspended sediment, turbid water, discoloration, and/or oil sheen shall be noted, as applicable. f. A description of any water quality monitoring performed during inspection, and the results of that monitoring. g. General comments and notes, including a brief description of any BMP r repairs, maintenance or installations made as a result of the inspection. 32 Stormwater Pollution Prevention Plan h_ A statement that, in the judgment of the person conducting the site inspection, the site is either in compliance or out of compliance with the terms and conditions of the S WPPP and the NPDES permit. If the site inspection indicates that the site is out of compliance, the inspection report shall include a summary of the remedial actions required to bring the site back into compliance, as well as a schedule of implementation. i. Name, title, and signature of person conducting the site inspection; and the following statement: "I certify under penalty of law that this report is true, accurate, and complete, to the best of my knowledge and belief'. When the site inspection indicates that the site is not in compliance with any terms and conditions of the NPDES permit, the Permittee shall take immediate action(s) to: stop, contain, and clean up the unauthorized discharges, or otherwise stop the noncompliance; correct the problem(s); implement appropriate Best Management Practices (BMPs), and/or conduct maintenance of existing BMPs; and achieve compliance with all applicable standards and permit conditions. In addition, if the noncompliance causes a threat to human health or the environment, the Permittee shall comply with the Noncompliance Notification requirements in Special Condition S51 of the permit. 33 5tormwater Pollution Prevention Plan Site Inspection Form General Information Element. ..VlaGlearngin�ts P. Location Inspected Fu Y 1" nmg. Frobleni/Correctifiction NIP: '$1 lrs ected ; Location Petiobing Problan. / rectivc diction Y N AY N . SNIP - LocationInspected; Y N. Ming NIP PIoblengCorrective-ction Probl6 CorrectiV1e Action` 34 Stormwater Pollution Prevention Plan Element 3: Control Flow Rates BMP: Location InspectedFuac Y N BMP: 1. Location BMP: Location Inspected';, Y N' �ning NIP Problem/Corrective Action Inspected Functioning Y . N FY 7N NIP Problem/Corrective Action Proble n/cor,rective Action 35 Stormwater Pollution Prevention Plan U� BMP: Location Inspected Functioning Y N� ` �`Y N Nu' Problem/Correctiw Action 36 Stormwater Pollution Prevention Plan Element 7: Protect Drain Inlets BMP: LocatiInspected Funct oning< ` ProblernlCo on Y N Y N 'NIP rrective>Action BMP: Location Inspected Y N:. Functionng . Probleii /Corrective Action BMP: Inspected' Functionin Location Y N Y N 'NIP Problem/Corrective Actiion and.4utleis 'Element S `'Stabilize, Channels BMP: Inspected Funcfi6nin& - :Location Problem/Corrective. Actiod ,Y N Y N NIP BMP. LocationInspected Functioning �Y N Y N NIP BMP: Vocation Inspected Y N Location Inspected Y N:, Problem/Corrective Action Problem/Corrective Action Functioning NIP Problen/Corrective Action Y N,�� 37 Stormwater Pollution Prevention Plan Element 9�ontra�l Pollutants 'BMP: Yns�cted' fun�tionmg Problem/Correctivc Action n Y I�t , Y N NIP Inspected Location , Y N BMP: - Location Inspected',- Location" Y 14 Problern/Correetive Adion` Problem/Corrective Action Problem/Corrective Action Problei /Corrective Action: 38 Stormwater Pollution Prevention Plan 39 Stormwater Pollution Prevention Plan Water Quali Mouitarin Was,any water quality monitoring conducted? ❑ Yes ❑ No if water quality monitoring was conducted, record. results here: 'i1lVili�{V ,y kY#;{.''.#47 AAA #'Als};1{A'F}+A lCFA1VV Vl,_1L1JLCiil6J.LiV1Ll, illflLLG,: LiJ CL,1 Va LAJA C71 L1kl� UA.3 VLIV11. -:.. Wer'eTh6t6s Tdkeri? ❑ Yes ❑ No If photos taken, describe bhotos below: 40 Stormwater Pollution Prevention Plan Appendix F — Engineering Calculations 41 z Description By j-E 0/ 6./ Date I3 I Checked Date ENGINEERING Scale Sheet No. 250 4th Ave. South Suite 200 Edmonds, WA 98020 project Job No. 425.778.8500 www_cgengineering.com ENGINEERING Source Controls Technical Information Report RENTON CENTER SENIOR LIVING —Project #13133.20 Business Type: Address: Activity Sheet Number Use this worksheet to identify the activities that you conduct. Interpret the categories broadly. Numbers A-1 — A-45 correspond to sheets located in Chapter 3. Do you conduct this activity? If so, where? TYPE OF ACTIVITY INDOORS OUTDOORS A-1 Required BMPs for All Commercial Properties f A-2 Storage of Liquid Materials in Stationary Tanks A-3 Storage of Any Liquid Materials in Portable Containers A4 Storage of Soil, Sand, and Other Erodible Materials A-5 Storage of Pesticides and Fertilizers A-6 Storage and Treatment of Contaminated Soils A-7 Storage and Processing of Food Items A-8 Storage of Solid Wastes and Food Wastes (Including Cooking Grease) A-9 Storage of Scrap and Recycling Materials (Including Auto Recycling Facilities) A-10 Treatment, Storage, or Disposal of Dangerous Wastes A-11 Cleaning or Washing of Tools and Equipment A-12 Cleaning or Washing of Cooking Equipment A-13 Vehicle Washing and Stearn Cleaning A-14 Interior Washing Operations (Including Mobile Contractors) A-15 A-16 Pressure Washing of Buildings, Rooftops, and Other Large Objects 'I-RANSFER OF L1Q1JQ MATERIALS Truck or Rail Loading and Unloading of Liquid Materials A-17 Fueling Operations A-18 A-19 Engine Repair and Maintenance tAPPLICATION Concrete and Asphalt Production at Stationary Sites A-20 Concrete and Asphalt at Temporary Sites A 21 Manufacturing and Post -Processing of Metal Products January 2009 King County Stormwater Pollution Prevention Manual Activity Sheet Number Use this worksheet to identify the activities that you conduct. Interpret the categories broadly. Numbers A-1 - A-45 correspond to sheets located in Chapter 3. Do you conduct this activity? If so, where? TYPE OF ACTIVITY INDOORS OUTDOORS A-22 Painting, Finishing, and Coating of Vehicles, Products, and Equipment A-23 Wood Treatment and Preserving A-24 Commercial Composting A-25 Chemical Applications -Other than for Landscaping LANDSCAPING A-26 Landscaping Activities A-27 Clearing, Grading, and Preparation of Land for Small Construction Projects A-28 Demolition of Buildings A-29 Building Repair, Remodeling, and Construction A-30 Boat Building, Maintenance, and Repair A-31 OTHER Vehicle and Equipment Parking and Storage A-32 Sidewalk Maintenance A-33 Swimming Pool and Spa Cleaning and Maintenance A-34 Keeping Animals in Controlled Areas A-35 Keeping Livestock in Stables, Pens, Pastures or Fields A-36 Logging and Log Yards A-37 Mining and Quarrying of Sand, Gravel, and Other Materials A-38 Well, Directional and Geotechnical Drilling A-39 Roof Vents and Fugitive Emissions (Including Dust) A-40 Street Deicing Operations A-41 Wheel Wash and Tire Bath Operations A-42 Potable Water Line Flushing or Tank Maintenance A-43 Use of Soil Amendments`on Construction Sites A-44 Dust Control and Soil Erosion and Sediment Control for Manufacturing and Other Commercial Operations A-45 Maintenance of Public and Private Utility Col;idors and Facilities King County Stormwater Pollution Prevention Manual January 2009 Required BMPs for All Commercial Properties MINIMUM REQUIREMENTS The following BMPs are required if you own or occupy commercial, industrial, agricultural, public, or multifamily residential property in unincorporated King County. Clean Your Storm Drainage System Maintain your storm drainage system by removing sediment and other debris to prevent the transport of pollutants into receiving waters. The storm drainage system includes all drains, catch basins, pipes, ditches, gutters, and flow control and water quality facilities. See BMP Info Sheet 7 in Chapter 5 for details on drainage system maintenance. Eliminate Illicit Connections to the Storm Drainage System A common situation that can cause severe stormwater pollution problems is discharge of non-stormwater to the storm drainage system. Examples are discharges from internal floor drains, appliances, industrial processes, sinks, and toilets. These are sometimes illegally or inadvertently connected or drained to the nearby storm drainage system. These discharges must go to the sanitary sewer system, a holding tank, an on -site process water treatment system, or a septic system. You must correct these illicit discharges. If you have any questions as to whether your discharge is allowable, contact the King County Water and Land Resources Division at 206-296-1900. See BMP Info Sheet 1 in Chapter 5 for information on how to check for illicit connections. You can also ask for help from your local sewer utility. if you find out that your internal drains are January 2009 King County Stormwater Pollution Prevention Manual Required BMPs for All Commercial Properties (continued) improperly connected to the storm drainage system, they will need to be either removed, permanently plugged, or connected to the sanitary sewer, septic system, on -site treatment system, or a holding tank. Stencil Your Storm Drains Stencil or apply storm drain markers adjacent to storm. drains to help prevent the improper disposal of pollutants. Storm drain inlets should have messages such as "Dump No Waste - Drains to Stream" applied next to the catch basin to warn against the intentional dumping or discharge of pollutants. If the metal catch basin grate has been cast with this message, marking the drains is still recommended, but may not be required unless evidence is found that pollutants are being dumped or washed to the storm drains. For more information or assistance in implementing these best management practices, contact the King County Department of Natural Resources and Parks Water and Land Resources Division at 206-296-1900. Reader Note: The above requirements are the minimum required BMPs. If these BMPs fail to prevent discharges to the storm drainage system, you will be asked to take additional measures to correct the continued pollution discharges. King County Stormwater Pollution Prevention Manual January 2009 Landscaping Activities and Vegetation Management This broad activity encompasses all aspects of landscaping and vegetation management, from small- scale yard maintenance to large-scale commercial landscaping businesses and vegetation management programs. It includes vegetation removal,; herbicide and insecticide application, fertilizer application, watering, and other gardening and Iawn care practices. Stormwater runoff from areas that have been subject to pesticide or fertilizer application or extensive clearing, grading or cutting may be contaminated with pesticides and other toxic organic compounds, metals, oils, suspended solids, nutrients from fertilizer, and colifoim bacteria, and may cause biochemical oxygen demand. While not required, consider using the Integrated Pest Management (IPM) approach for pest control. IPM is an approach that uses an array of methods to manage pest damage with the least possible hazard to people and the environment. IPM uses a combination of biological, cultural, and physical practices that can significantly reduce or eliminate the use of pesticides. See Activity Sheets A-5, "Storage of Pesticides and Fertilizers" and A-3, "Storage of Liquid Materials in Portable Containers." Landscaping activities related to golf courses should refer to King County's Golf Course BMP Manual (see Chapter 6 of this manual for more information). Note: The term pesticide includes insecticides, herbicides, fungicides, rodenticides, etc. The following BMWs, or equivalent measures, methods, or practices are required if you are engaged in landscaping activities: Do not apply any pesticides directly to surface waters, unless the application is approved and permitted by the Washington State Department of Ecology. Mix pesticides so that spilled material will not be washed to surface waters, the storm drainage system, or onto the ground. Clean up any spills immediately. Ensure employees are trained on the proper use of pesticides and in pesticide application techniques to prevent pollution. Washington pesticide law requires most businesses that commercially apply pesticides to the property of another to be licensed as a Commercial Applicator. Follow manufacturers' recommendations and label directions. Pesticides and fertilizers must never be applied if it is raining or about to rain. Do not apply pesticides within 100 feet of surface waters such as lakes, ponds, wetlands, and streams. This also can include stormwater conveyance ditches. Remove weeds/vegetation in stormwater ditches by hand or other January 2009 King County Stormwater Pollution Prevention Manual Landscaping Activities and Vegetation Management (continued) mechanical means. Chemicals should be used as a last resort. Dispose of grass clippings, leaves, branches, sticks, or other collected vegetation, by recycling, composting, or burning (if allowed). Do not dispose of collected vegetation into storm drainage systems, conveyance ditches, stormwater ponds, or surface water. Use mulch or other erosion control measured when soils are exposed for more than one week during the dry season or two days during the rainy season. Implement water conservation practices to assure sprinkler systems do not "overspray" vegetated areas and discharge to hard surfaces such as sidewalks, driveways, and parking lots. Adjust sprinkler heads accordingly. Minimize water use so runoff does not occur or enter storm drainage systems. Use approaches to reduce water use such as those described in the Natural Yardcare program. http://your.kingcounty.gov/solidwaste/naturalyardr-are/watering.asp The King County Noxious Weed Control Program provides best management practices for the removal of typical noxious weeds such as blackberry and purple loosestrife. Call 206-296-0290 or see http://www.kingcounty.gov/environment/animalsandplants/noxious- weeds/weed-control-practices.aspx for more information. The following BMPs are optional unless the above minimum required BMPs do not provide adequate source control: Integrated pest management (IPM), a comprehensive approach to the use of pesticides is the most effective BMP measure that can be taken for herbicide, insecticide, and fungicide use. � See BMP Info Sheet 6 in Chapter 5 for information on IPM. Fertilizers should be worked into the soil rather than dumped or broadcast onto the surface. Determine the proper fertilizer application for the types of soil and vegetation involved. Soil should be tested for the correct fertilizer usage. Use mechanical methods of vegetation removal rather than applying herbicides. King County Ston-nwater Pollution Prevention Manual January 2009 Landscaping Activities and Vegetation Management (continued) An effective measure that can be taken to reduce pesticide use, excessive watering, and removal of dead vegetation involves careful soil mixing and layering prior to planting. A topsoil mix or composted organic material should be rototilled into the soil to create a transition layer that encourages deeper root systems and drought -resistant plants. This practice can improve the health of planted vegetation, resulting in better disease resistance and reduced watering requirements. Use native plants in landscaping. Native plants do not require extensive fertilizer or pesticide applications. For more information or assistance in implementing these best management practices, contact the King County Department of Natural Resources and Parks Water and Land Resources Division at 206-296-1900. Reader Note: The above requirements are the minimum required BMPs. If these BWs fail to prevent discharges to the storm drainage system, you will be asked to take additional measures to correct the continued pollution discharges. January 2009 King County Stormwater Pollution Prevention Manua! Building Repair, Remodeling, and Construction This activity applies if you are engaged in common on -site labor activities associated with construction of buildings and other structures, remodeling of existing buildings and houses, painting of building exteriors, and general exterior building repair work. Stormwater runoff from building repair, remodeling, and construction work can be contaminated with toxic hydrocarbons in solvents, other toxic organic compounds, suspended solids, metals, abnormal pH, and oils and greases. Concrete pouring is covered under Activity Sheet A-20,"Concrete and Asphalt Application at Temporary Sites." The following BMPs, or equivalent measures, methods, or practices are required if you are engaged in building repair, remodeling, and construction: Do not dump any substance, wash water or liquid waste on the pavement, the ground, or toward a storm drain or drainage ditch. Use ground or drop cloths underneath outdoor painting, scraping, and sandblasting work and properly dispose of collected material daily. Use a ground cloth or oversized tub for activities such as paint mixing and tool cleaning. Dispose of all wash water from tool cleaning to the sanitary sewer system. Never dispose of wash water to on -site yard drains or street drains. Never dispose of any wash water to a storm drain. Clean paint brushes and tools covered with water -based paints in sinks connected to sanitary sewers or in portable containers that can be dumped into a sanitary sewer. Brushes and tools covered with non -water -based paints, finishes, or other materials must be cleaned in a manner that enables collection of used solvents (e.g., paint thinner, turpentine, etc.) for recycling or proper disposal. CZ&_ See BMP Info sheet 2 in Chapter 5 for information on disposal options. January 2005 i King County Stonnwater Pollution Prevention Manual Building Repair, Remodeling, and Construction (continued) Use a storm drain cover, biter fabric, or similarly effective runoff control mechanism if dust, grit, wash water, or other pollutants may escape the work area and enter a catch basin. This is particularly necessary on rainy days. The containment device(s) must be in place at the beginning of the workday, and accumulated dirty runoff and solids must be collected and disposed of in an appropriate manner before removing the containment device(s) at the end of the workday. For example, a combination of a wet vacuum and brooms and dustpans could be used to collect accumulations of dirty runoff. Drain covers, filter fabric, and other containment devices are commercially available if effective runoff control cannot otherwise be provided. If you need to dewater an excavation site, you must filter the water before discharging to a catch basin or discharging off -site. You should direct the water through sediment filters or traps or use an equivalent method. The pH of water from dewatering activities must be monitored. If the pH is not neutral (7), discharge must not occur to a drainage system until the water is neutralized through an approved method. Dewatering must also be assessed for other pollutants that may not be removed by simple filtering of stormwater. If other pollutants are present, discharging the water to surface or stormwater systems may not be allowed. See Appendix D of the King County Surface Water Design Manual, "Erosion and Sediment Control Standards." Routine Maintenance: • Store and maintain appropriate spill cleanup materials in a location known to all. Ensure that employees are familiar with proper spill cleanup procedures. • Sweep paved areas as needed and collect loose particles for proper disposal. Wipe up spills with rags and other absorbent material immediately. Do not hose down the area to a storm drain. • Store toxic material under cover during precipitation events and when not in use (such as overnight). A cover would include tarps or other temporary cover materials. C:N= See Activity Sheet 3, "Storage of Liquid Materials Portable Containers." King County Stormwater Pollution Prevention Manual January 2009 Building Repair, Remodeling, and Construction (continued) The following BMPs are optional unless the above minimum required BMPs do not provide adequate source control: Recycle or reuse left over materials. A catch basin insert configured for debris and sediment removal may remove some of the pollutants in runoff from this activity. Catch basin inserts require frequent maintenance to be effective. Carefully consider this when evaluating your options. See BW Info Sheet 10 in Chapter 5 for more information. For more information or assistance in implementing these best management practices, contact the King County Department of Natural Resources and Parks Water and Land Resources Division at 206-296-1900. Reader Note: The above requirements are the minimum required BMWs. If these BMPs fail to prevent discharges to the storm drainage system, you will be asked to take additional measures to correct the continued pollution discharges. January 2009 King County Stormwater Pollution Prevention Manual Illicit Connections An illicit connection is a connection that could convey anything not composed entirely of surface and stormwater directly to the storm drainage system or a water body. Many buildings throughout King County could have illicit connections to the storm drainage system. These typically include, but are not limited to, sanitary sewer pipes, process wastewater discharges, sump overflows, and internal building drains connected to the storm drainage system. As a result of illicit connections, wastewater containing a variety of pollutants is discharged directly to storm drains and drainage ditches, and ultimately to receiving waters rather than to the sanitary sewer system or a septic system. In many instances these connections are unknown to the business or property owner, and may not show up on building drawings. Elimination of illicit storm drainage connections is an important facet of stormwater pollution reduction and must be addressed as a top priority. King County is currently making a committed effort to determine where illicit connections are present and to require their removal. All businesses, residents and public agencies in unincorporated King County must investigate their plumbing/drainage systems to determine if there are any illicit connections to the storm drainage system, such as internal floor drains plumbed to the storm drainage system. If building and property drawings are available with plumbing details, they should be reviewed to understand pipe connections. If you are unsure whether a particular drain (such as a floor drain) discharges to the storm drainage system, you should identify where the potential illicit connection drains to by consulting plans, side sewer cards, and possibly conducting a dye test. Running water from a hose into the drain and observing where the water discharges is often a very simple and effective method of identifying illicit connections. Any pipes or other conveyances connected to storm drainage facilities that drain anything but stormwater must be permanently plugged or rerouted to a sanitary sewer, holding tank, on -site process treatment system, or septic system (with approval from the appropriate agencies or jurisdiction). If building plans and side sewer cards do not show your plumbing, the most basic methods for determining a connection is either dye tracing or running water through the system. A nontoxic dye can be put in water and flushed or drained into the suspect piping. Observations should then be made in catch basins, manholes, drainage ditches, or other storm drainage conveyances that January 2009 icing County Stormwater Pollution Prevention Manual are present on site (or adjacent to the property) to search for the dye. Enough water must be poured or flushed through the indoor drain to force the flow to reach the point(s) of observation.. If possible, all other drains in the building should be out of use while the dye test is conducted to ensure the results can pinpoint the problem drain. This test should be conducted for each suspect drain on the property. Any observations of dye in the storm drainage system must be noted and the corresponding indoor drains tagged for followup plugging or rerouting. If you are uncertain as to the locations of catch basins or manholes that can be used for observation, or if you can not determine how the storm drainage system is constructed on your property, contact the King County Water and Land Resources Division (WLRD) at 206-296-1900 for assistance. Notify WLRD at least one day in advance if you are performing a dye test. ELIMINATING AN ILLICIT CONNECTION Drains and pipes that are found to connect to the storm drainage system and have the potential of discharging pollutants or wastewater must either be permanently plugged or disconnected and rerouted as soon as possible. Drains that are no longer needed can be plugged with concrete or another similarly effective material. Whenever process water, stormwater, or other wastewater is redirected to the sanitary sewer, the local sewer authority and the King County Industrial Waste Program must be contacted to obtain approval for discharging to the sanitary sewer. The local sewer authority and King County must also be contacted prior to the installation of any permanent connection to the sanitary sewer. The name of your local sewer authority is identified on your water and sewer bill. The local sewer authority and King County Industrial Waste will regulate the connection both for discharge quantity and quality, but the responsible party will have to arrange for the necessary plumbing supplies and pipe disconnection/rerouting work. If a sanitary sewer does not service the property, and one is not available for hookup, alternative measures are necessary. If the discharge is domestic wastewater from a toilet, sink, appliance, or shower/bathtub, a septic system can be used to receive the rerouted discharge. The connection of plumbing fixtures to an on -site sewage disposal system usually requires an on -site sewage disposal system repair permit. Therefore, before any pipes are rerouted, the Seattle -King County Department of Public Health must be contacted for further information. If a septic system is not present on the property then one should be installed. The Seattle -King County Department of Public Health should be contacted for advice and information on septic system requirements. If the discharge is industrial process water or other nondomestic wastewater, a holding tank or on - site treatment system will be needed. If an illicit connection needs to be rerouted to a holding tank, King County Water and Land Resources Division staff should be contacted for assistance and information on tank content disposal requirements. As with septic system and sanitary sewer hookups, the property owner or responsible business operator is responsible for rerouting the illicit pipe connections. January 2009 King County Stonnwater Pollution Praevenfion Manua! Disposal Options Every business, property owner, and public agency in King County must dispose of solid and liquid wastes and contaminated stormwater properly. There are generally five options for disposal depending on the types and quantity of materials. These options are: (1) sanitary sewer system, (2) septic system, (3) recycling, (4) municipal solid waste disposal facilities, and (5) waste transportation and disposal services. Ordinary stormwater runoff is not considered to be contaminated to the point of requiring special disposal. Stormwater that is mixed with concentrated wastes requires special disposal, as discussed below. Process wastewater (depending on the pollutants and associated concentrations present) can be put into the sanitary sewer, subject to approval by the local sewer authority and the King County Industrial Waste Program. Animal waste can be disposed of in a sanitary sewer, subject to loading capacity constraints. The King County Industrial Waste Program may require that all stormwater discharged to a sanitary sewer be metered. Sewer fees may be collected on such discharges. The first priority is to discharge process water to a sanitary sewer using an existing plumbing connection or a new pipe connection. Whenever the diversion of any process water or other wastewater to the sanitary sewer is needed, the local sewer authority and King County must be contacted to obtain approval prior to discharging to the sanitary sewer. Pretreatment of discharges to remove some of the process water pollutants may be required to obtain approval. The local sewer authority and King County must also be contacted prior to the installation of any permanent connection to the sanitary sewer. The name of your local sewer authority is identified on your water and sewer bill. Sumps or other temporary storage devices may be useful for storing liquid wastes on a temporary basis if you cannot discharge to a sanitary sewer system. Consideration should be given to using a holding tank for process water if the volume of process water generated by the activity is not excessive. See BW Info Sheet 4 for more information on holding tanks. The contents of the holding tank must be pumped out or drained before the tank is full. Several commercial services are available for pumping out sumps and holding tanks. These can be found in your telephone directory's yellow pages under the headings "Sewer Contractors and Cleaners" and "Tank Cleaning," or on the King County Stormwater Services website at http://www.kingcounty.gov/environment/waterandiand/stormwater/problem-investigation- line/drainage_maint vendors.aspx. Septic system pumpout and hauling contractors must not be used for disposing wastes other than domestic sewage. They are not allowed to haul industrial wastes. January 2009 King County 5tonnwater Pollution Prevention Manual BMP Info Sheet #2, Disposal Options (continued) If your site is not serviced by a sanitary sewer system, you probably have a septic system. Only liquid waste that is comparable to residential sewage in strength and constituency may be disposed of in septic systems. Hazardous chemicals cannot be disposed of in septic systems. Further, the septic system must be designed to accommodate the volume of suitable wastewater generated. Any changes in waste volume and constituency from those present when the system was permitted must be approved by the Seattle -King County Department of Public Health. Stormwater, whether contaminated or not, may not be disposed of in septic systems. Animal waste may not be disposed of in a septic system designed for single family, multifamily or commercial properties. Recycling facilities are a recommended option for many commercial items, including used oils, used batteries, a variety of used auto parts, metal scrap materials, solvents, paints, and other solid wastes. There are a number of private businesses that accept materials for recycling. In addition there is an Industrial Material Exchange clearinghouse which facilitates the transfer of unwanted materials from the generator to another business that can use them. The Industrial Material Exchange or DAEX website is http://www.govlink.org/hazwasteibusiness/imex. Process wastewater such as wash water can be recycled on -site as an alternative to discharge to the sanitary sewer. There are numerous products on the market that are designed to recycle wash water. Contact the King County Water and Land Resources Division at 206-296-1900 for more information. MUNICIPAL SOLID WASTE DISPOSAL FACILITIES Municipal solid waste disposal facilities are designed to handle solid wastes. Hazardous and dangerous wastes and many liquid wastes must be properly disposed of at an appropriate facility. Contact your local solid waste disposal facility or see http://your.kingcounty.gov/solidwaste/ garbage-recycling/index.asp for information on which materials are accepted at these facilities. Call the Business Waste Line at 206-296-3976 or see http://www.govlink.org/bazwasteAbusiness for information on the proper disposal of oil, antifreeze, and other hazardous wastes. WASTE TRANSPORTATION AND DISPOSAL SERVICES There are numerous services that can help you identify, quantify, transport, and dispose of any waste that you may generate. Many people have their wastes picked up by a disposal contractor. Costs of disposal vary considerably depending on the types of materials, quantities, methods of collection and transport, and whether the wastes are mixed. The rate the contractor charges will generally reflect the costs of testing and/or treating waste materials (if necessary) and the subsequent disposal. It is important to keep different types of wastes separated, so that the disposal contractor(s) can take them to the appropriate place(s) without causing inadvertent contamination problems elsewhere, and so that you are not paying too much for disposal of January 2009 King County Stormwater Polfution Prevention Manual BMP Info Sheet #2, Disposal Options (continued) materials that are not contaminated (e.g. regular garbage). If you are properly implementing your BMPs and collect contaminated waste materials for proper disposal, your efforts are compromised if a disposal contractor subsequently disposes the contaminated materials as regular garbage. Therefore, it is essential to be familiar with disposal alternatives and the different types of contractors for each disposal option. The Seattle -King County Department of Public Health's Waste Characterization Program serves hazardous waste generators in Seattle and King County that have questionable wastes. Information supplied by the generator on questionable wastes such as sludges, sandblast waste, treated wood, and contaminated soils is reviewed by the Health Department. Permits are issued for those wastes that will be allowed in the garbage. The dangerous waste regulations as well as other criteria are used in the decision process. The disposal of wastes is the responsibility of the generator. Before agreeing to let a company handle your waste, it is recommended that you ask for (and check) the company's references. All waste collected by the company should be delivered to an authorized site. Make sure you keep copies of all your transactions. Transfer of waste to a vender does not release you from legal obligation for disposal to a licensed disposal facility. January 2009 King County Stormwater Pollution Prevention Manual Integrated Pest Management The use of herbicides, insecticides, fungicides, and rodenticides can be extremely harmful to the environment due to the highly toxic nature of many chemicals in pesticide products. In light of this, special attention should be given to pesticide use in all applications. The discussion below applies more to large scale pesticide users, but should be considered for backyard applications as well. Commercial, agricultural, and other large scale pesticide users such as golf courses and parks should adhere to the principles of integrated pest management (IPM), a decision -making process for pest management that strives for intelligent, environmentally sound control of pests. It is a systems approach to pest management that combines agronomic, biological, chemical, and genetic information for educated decisions on the type of control(s) to use, the timing and extent of chemical application, and whether nonchemical means can attain an acceptable level of pest control. IPM is a preventive measure designed for the exact pest(s) being targeted for control, the locations and times when pests will pose problems, the level of pest -induced damage that can be tolerated without taking action, the most vulnerable life stage, and control actions that are least damaging to the environment. The major components of IPM are as follows: monitoring and inventory of pest populations, determination of pest -induced injury and action levels, identification of priority pest problems, selection and timing of least toxic management tools, site -specific treatment with minimized chemical use, and evaluation and adjustment of pesticide applications. Monitoring of pest populations is a key to successful IPM implementation. Pest problems are universally easier to control if the problem can be discovered early. With IPM pesticides are used only as a last resort; maximization of natural controls, including biological controls and removal of pests by hand, is a guiding rule. A list of IPM resources is available on the web at btip://www.govlink.org/bazwaste/interagency/il2nVindex.efin or httlp://www.aovlink.orZI hazwaste/publications/WMKCGuidelines.pdf. January 2009 King County Stormwater Pollution Prevention Manual Maintenance of Drainage Systems Many commercial, industrial, residential and public agency properties have storm drainage flow control and water quality systems to capture and treat storm%.�ater flows. Most of these systems have catch basins as key components. Catch basins are typically located along curbs, at low spots in parking lots, and where stormwater conveyance pipes combine flows. Storm drains collect runoff that directs flows into basins and pipes that are located underneath parking lots and storm drain grates. Most catch basins have a few feet of storage in the bottom or sump. This storage area is intended to trap sediment, debris, and other particulates that settle out of stormwater, to prevent clogging of downstream pipes and to keep solids from being flushed into receiving waters. Anyone who has ever looked into a catch basin can attest to its ability to capture dirt, leaves, twigs, litter, and a variety of other materials that make for a mucky buildup in the bottom. However, if the sump (the bottom of the catch basin) is full of solid material, everything in the incoming runoff passes straight through to an outflow pipe. The bottom (or sump) in catch basins must be cleaned out periodically so they can continue to trap solids from stormwater runoff. Routine maintenance practices at all sites with storm drains and catch basins must include cleaning/removal of sediment or solids from these important drainage system features. If catch basins are not cleaned, they can actually contribute to receiving water pollution problems as trapped solids, and stagnant, polluted water in sumps can be flushed out in large quantities with turbulent storm flow conditions. Check your catch basins annually for needed maintenance timed to occur before the rainy season. For organizations with large numbers of catch basins (greater than 50 per site), inspections may be conducted on a "circuit basis" whereby sampling of representative catch basins, including the lowest one in the circuit, within each circuit is inspected to identify clean - out needs for the circuit. The annual catch basin inspection schedule may be changed as appropriate to meet the maintenance standards based on maintenance records of double the length of time of the proposed inspection frequency. Catch basins must be cleaned out when the solids, trash, and debris in the sump reaches one-half of the depth between the bottom of the sump and the bottom (invert) of the lowest inflow or outflow pipe connected to the catch basin or at least 6 inches below this invert. The rate at which a sump fills with solid material is quite variable, and depends on the characteristics of the drainage basin feeding into it. if activities that generate a lot of sediment are taking place in the drainage area that contributes stormwater flows to a catch basin, such as exposing soils due to construction or landscaping, stockpiling erodible materials, or if your, site is not paved and has heavy traffic use on dirt or gravel surfaces, the sump will fill up relatively quickly. Therefore, sites with activities generating a lot of sediments and other debris will have to inspect and clean out their catch basins more often. i January 2009 King County 3tonnwater Pollution Prevention Manual BMP Info Sheet #7, Maintenance of Drainage Systems (continued) Other components of drainage systems include ponds, tanks, and bioswales. These components must also be maintained to ensure your drainage systems functions as designed. Vegetation in ponds and bioswales must be mowed or thinned, and sediment accumulations must be removed. Maintenance of ponds, tanks, and bioswales is generally beyond the ability of the typical property owner. Drainage system maintenance contractors are available to complete this work. If you clean out/maintain the catch basins yourself, you may dispose of up to one cubic yard of solid material as solid waste in your regular garbage. If you exceed this threshold you are encouraged to contact a company offering catch basin cleaning services. You can locate a cleaning service by calling the King County Water and Land Resources Division at 206-296-1900 for a list of firms performing drainage system maintenance services or in your telephone directory's yellow pages under headings like "Sewer Cleaning Equipment and Supplies," "Sewer Contractors," and "Tank Cleaning." All of the solids and stagnant water collected from catch basin sumps must be disposed of properly. None of the sump contents can be flushed into the catch basin outflow pipe. Depending on the nature of the pollutants in the sump, and the associated types of activities taking place on the site, the sump contents may need to be handled as contaminated waste. Contractors who perform catch basin clean -out services are required to follow appropriate disposal requirements. Frequent sweeping of paved parking and storage areas, covering pollutant generating activity areas, and containing runoff from activity areas will help reduce catch basin and drainage system cleaning frequency, and may save time and money spent on required maintenance. All businesses and public agencies should set up maintenance schedules for all of their BMPs so that coordinated BMP efforts result in reduced catch basin and drainage system maintenance and cleaning. January 200.9 King County Stormwater Pollution Prevention Manual C C ENGINEERING TIR SECTION 9: BOND QUANTITIES, FACILITY SUMMARIES, AND DECLARATION OF COVENANT Technical Information Report RENTON CENTER SENIOR LIVING — Project #13133.20 ENGINEERING Bond Quantities Technical information Report RENTON CENTER SENIOR LIVING — Project #13133.20 r2 O N N N co 0 0 0 0 rn N 0 N c� U -0 w E L. 0 ca c a� c� 0 LL 41 41 R C C 0 W ,r OZi N � n G1 Al Ln >, C a a co E o y a to ai too C p ta � E �U o 1p O 0 n SM Q tp Ln N 2' 0 0 (a z z o y A a 3 aJ� L y O � C E O N w a N O 0 0 0 ui 0 3 E cr 3 N � O ai as m a L i U � U � CD a CD U � L c 0 c O co 0 N N 4-1 i a co 0 0 m W E 0 E :a) co - co OO (D N (•7 O N N N It w O U T T r r C O CL (¢ co co r a (O N T C t4 3 a C r �rrrt-U-rrrrU-U-I1}r 0 0 uI- U- 0 U w U U U -j J co co w co J J J w U J J co 0 0�= W W W W N r u7 00 O W W to LO a M O 00 O W'It CO CO CO U-? U-) Ln ID LO V O W1 M M to llf O Lt7 h t- f+ M O Cl? 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I" N W z r N dN M C Z Z) 0 m � m a ¢ 0 o w.0 CL E Ea ffi b3 69 4A �} ,C Q U O + H U ~ * 0 C m II U = m N cn C: 26 0 W U. o o U o a) ED -0 + o o m v� ~ C: ; G N 6R O E `v E E o 'v o m c a 0 o �' O U _3 E ¢ °� O m C x A O C m t7 ?' N 4 rn E y - m E Q LU m ,V O Z) C)0 U 0 N IL � 40 Ol a [6 N y 0 w li a U C 0 61 y L) m y y � 0 U E C Vl 'rq IC Q1 y G � � O E o L 0 i0 E N T K � 9 }r ELV N a a) O L y N T Q O E O U c E 0 y c sa c y rr 0 y E C C w M 0 @ 6 E -C C_ 7 y a T 0 6 E U M — E :E0 m E d I6 f0 Q U P L E d o C 0 @ O A N m O O Q L IL L 3 'c ui 0 h n E aci (U G N N ID L E m n S U E °c m n LU c _C) y E @ = C O c y '� �+ E O C W U y O Q 0 o cc y O cn y w y0 M C N .Q-1 N t9 L C O cc •C Q7 C C — y 3 y c6 C 0 c w m 0 N c c a y -0 fU (D f6 N L N 0 3 N C y Y (D F- Y 00 0 z z z N CO CO 0 0 a r N N N T (D "D C `- -O k2 N aj C) (1) o Q7 Q U Lr a C D m Q O) N ra CL C -ate ENGINEERING STORMWATER FACILITY SUMMARY SHEET DDES Permit Number: n/a (provide one Stormwater Facility Summary Sheet per Natural Discharge Location) Overview: Project Name Renton Center Senior Living DaIg October 2013 Downstream Drainage Basins Major Basin Name Green/Duwamish Immediate Basin Name Flow Control Flow Control Facility Name/Number Permeable Pavers Facility Location Courtyards on south side of the building, in the east, plaza If none, Flow control provided in regional / shared facility (give location) . N/A No flow control required Exemption Number General Facility Information Type/Number of detention facilities: 0 ponds 0 vaults 0 tanks Control Structure Location NIA Type of Control Structure Number of Orifices / Restrictions Type/Number of infiltration facilities: 0 ponds 0 tanks 0 trenches (dispersion) Size of Orifice / Restriction: No. 1 N/A No. 2 No. 3 No. 4 Flow Control Performance Standard Peak Rate Flow Control Technical Information Report RENTON CENTER SENIOR LIVING — Project #13133.20 ENGINEERIiVG STORMWATER FACILITY SUMMARY SHEET (Continued) Live Storage Volume N/A Depth Volume Factor of Safety (Sized per Table C.2.1.A in 2009 KCSWDM) Number of Acres Served N/A Number of Lots Dam Safety Regulations (Washington State Department of Ecology) Reservoir Volume above natural grade N/A Depth of Reservoir above natural grade NIA Facility Summary Sheet Sketch All detention infiltration and water quality facilities must include a detailed sketch. (11" x 17" reduced size plan sheets may be used) See attached 11" x 17" drainage plan. Technical Information Report RENTON CENTER SENIOR LIVING — Project #13133.20 C � ENGINEERING Declaration of Covenant To he completed in future phases of this project_ Technical Information Report RENTON CENTER SENIOR LIVING — Project #13133.20 C C ENGINEERING TIR SECTION 10: OPERATIONS AND MAINTENANCE MANUAL The proposed storm system consists of catch basins that capture on -site runoff and route it through conveyance pipes to the City storm system. Permeable Pavement has been implemented in some areas of the site and will need to be maintained as well. Included in this Operation and Maintenance Manual is an 11" x 17" grading and drainage plan sheet showing the location of these facilities on the plan. Please note that this map is generated during the design phase and may not reflect all changes made in permitting and construction. CG Engineering may be contacted for an updated copy of this map once the as -built drawings are completed for the site. Exxel Pacific (project contractor) will be responsible for passing along the information in this maintenance manual to the property management company for the senior apartments. This manual shall be kept in offices of the proposed building. Upon request by the City of Renton, it shall be made available for their inspection. Included in this manual are facility specific sheets indicating the various maintenance components of the following facilities: Catch Basins: Concrete structures with steel grates that collect stormwater runoff from the site and act as junctions for storm conveyance pipes. Conveyance Pipes: Conveyance Pipes will run the flow to appropriate locations as shown on the plan sheets. Landscaping: Landscaping throughout the site will require maintenance as indicated in the included specification sheet. Stormfilters: Stormfilters are located in manholes and are designed to treat the stormwater prior to detention. Permeable Pavement: Pavement with pourous openings that allows stormwater to infiltrate into the ground. Because King County has not developed a specific maintance sheet for permeable pavements, recommendations are included from the 2012 Low Impact Development Technical Guidance Manual for Puget Sound by Washington State University Extension and Puget Sound Partnership. Facilities shall be inspected for defects listed in the following facility sheets. The frequency of this should occur as noted on the sheets (A = annually (in September), W = at least once during the wet season, etc). Most maintenance tasks are generally reactionary to a defect being found, rather than a matter of constant upkeep. It is generally expected that few to none of these defects will be present upon the yearly inspection of each facility. The facility sheets list the potential conditions warranting maintenance and the expected result following any maintenance. Several engineer's notes for specific tasks are provided within the facility sheets. Unless otherwise noted on the facility sheets the maintenance tasks should be performed on an "as needed" basis: (a) when the described defect is visible to whomever performs the yearly inspection, or (b) should any defect become apparent between inspections. Technical Information Report RENTON CENTER SENIOR LIVING — Project #13133.20 C 4 ENGINEERING Maintenance Requirement Sheets Technical Information Report RENTON CENTER SENIOR LIVING—Project#i13133.20 APPENDIX A MAINTENANCE REQUIREMENTS FOR. FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES NO.5 - CATCH BASINS AND MANHOLES Maintenance Defect or Problem Condition When Maintenance is Needed Results Expected When Component Maintenance is Performed Structure Sediment Sediment exceeds 60% of the depth from the Sump of catch basin contains no bottom of the catch basin to the invert of the sediment. lowest pipe into or out of the catch basin or is within 6 inches of the invert of the lowest pipe into or out of the catch basin. Trash and debris Trash or debris of more than Y. cubic foot which No Trash or debris blocking or is located immediately in front of the catch basin potentially blocking entrance to opening or is blocking capacity of the catch basin catch basin. by more than 10%. Trash or debris in the catch basin that exceeds '13 the depth from the bottom of basin to invert the No trash or debris in the catch basin. lowest pipe into or out of the basin_ Dead animals or vegetation that could generate No dead animals or vegetation odors that could cause complaints or dangerous present within catch basin. gases (e.g., methane). Deposits of garbage exceeding 1 cubic foot in No condition present which would volume. attract or support the breeding of insects or rodents. Damage to frame Comer of frame extends more than % inch past Frame is even with curb, and/or top slab curb face into the street (If applicable). Top slab has holes larger than 2 square inches or Top slab is free of holes and cracks. cracks wider than % inch_ Frame not sitting flush on top slab, i_e_, Frame is sitting flush on top slab. separation of more than % inch of the frame from the top slab. Cracks in walls or Cracks wider than h inch and longer than 3 feet, Catch basin is sealed and bottom any evidence of soil particles entering catch structurally sound. basin through cracks, or maintenance person judges that catch basin Is unsound. Cracks wider than % inch and longer than 1 foot No cracks more than 114 inch wide at at the joint of any inletloutlet pipe or any evidence the joint of inlet/oLAel pipe. of soil particles entering catch basin through cracks. Settlementl Catch basin has settled more than 1 inch or has Basin replaced or repaired to design misalignment rotated more than 2 inches out of alignment, standards. Damaged pipe joints Cracks wider than'r4-inch at the joint of the No cracks more than N.-inch wide at inlel/ouflet pipes or any evidence of soil entering the joint of inletioutlet pipes. the catch basin at the joint of the inletloullet pipes. Contaminants and Any evidence of contaminants or pollution such Materials removed and disposed of pollution as oil, gasoline, concrete sluntes or paint. according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Inlet/Outlet Pipe Sediment Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment. accumulation Trash and debris Trash and debris accumulated in inletfoutiet No trash or debris in pipes. pipes (includes ffoatables and non-Boatables). Damaged Cracks wider than at the joint of the No cracks more than YAnch wide at inletloullet pipes or any evldenoe of soil entering the joint of the inietloutlet pipe, at the joints of the inlet/outlet pipes. 2009 Surface Water Design Manual — Appendix A 1/9/2009 A-9 APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES NO.5 - CATCH BASINS AND MANHOLES Maintenance Defect or Problem Condition When Maintenance is Needed Results Expected When Component Maintenance is Performed Metal Grates Unsafe grate opening Grate with opening wider than'/$ inch. Grate opening meets design (Catch Basins) standards. Trash and debris Trash and debris that is blocking more than 20% Grate free of trash and debris. of grate surface. footnote to guidelines for disposal Damaged or missing Grate missing or broken member(s) of the grate. Grate is in place and meets design Any open structure requires urgent standards. maintenance. Manhole CoverlLid Cover/lid not in place Coverllid is missing or only partially in place. CoverAid protects opening to Any open structure requires urgent structure. maintenance. Locking mechanism Mechanism cannot be opened by one Mechanism opens with proper tools. Not Working maintenance person with proper tools. Bolts cannot be seated. Self-locking cover/iid does not work- Cover/lid difficult to One maintenance person cannot remove Coverflid can be removed and Remove coverllid after applying 80 lbs. of lift reinstalled by one maintenance person. 1/9/2009 2009 Surface Water Design Manual — Appendix A A-10 APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES NO.6 - CONVEYANCE PIPES AND DITCHES Maintenance Defect or Problem Conditions When Maintenance is Needed Results Expected When Component Maintenance is Performed Pipes Sediment & debris Accumulated sediment or debris that exceeds Water flows freely through pipes. accumulation 20% of the diameter of the pipe. Vegetationfroots Vegetatiordroots that reduce free movement of I Water flows freely through pipes. water through pipes. Contaminants and Any evidence of contaminants or pollution such Materials removed and disposed of pollution as oil, gasoline, concrete slurries or paint. according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Damage to protective Protective coating is damaged; rust or corrosion Pipe repaired or replaced, coating or corrosion Is weakening the structural integrity of any part of pipe. Damaged Any dent that decreases the cross section area of Pipe repaired or replaced. pipe by more than 20% or is determined to have weakened structural integrity of the pipe. Ditches Trash and debris Trash and debris exceeds 1 cubic foot per 1,000 Trash and debris cleared from square feet of ditch and slopes. ditches. Sediment Accumulated sediment that exceeds 20% of the Ditch cleaned/flushed of all sediment accumulation design depth. and debris so that it matches design_ Noxious weeds Any noxious or nuisance vegetation which may Noxious and nuisance vegetation constitute a hazard to County personnel or the removed according to applicable public. regulations_ No danger of noxious vegetation where County personnel or the public might normally be. Contaminants and Any evidence of contaminants or pollution such Materials removed and disposed of pollution as oil, gasoline, concrete slurries or paint. according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film, Vegetation Vegetation that reduces free movement of water Water flows freely through ditches. through ditches. Erosion damage to Any erosion observed on a ditch slope. Slopes are not eroding_ slopes Rock lining out of One layer or less of rock exists above native soil Replace rocks to design standards. place or missing (If area 5 square feet or more, any exposed native Applicable) soil. 2009 Surface Water Design Manual — Appendix A 1/9/2009 A-11 APPENDIX A MAINTENANCE REQUiRE-M> NTS PIAW CONTROL, CONVEYANCE, AND WQ FACILITIES NO. 11 -GROUNDS (LANDSCAPING) Maintenance Defect or Problem Conditions When Maintenance is Needed Results Expected When Component Maintenance is Performed Site Trash or litter Any trash and debris which exceed 1 cubic foot Trash and debris cleared from site. per 1,000 square feet (this is about equal to the amount of trash it would take to fill up one standard size office garbage can). In general, there should be no visual evidence of dumping. Noxious weeds Any noxious or nuisance vegetation which may Noxious and nuisance vegetation constitute a hazard to County personnel or the removed according to applicable public. regulations. No danger of noxious vegetation where County personnel or the public might normally be. Contaminants and Any evidence of contaminants or pollution such Materials removed and disposed of pollution as oil, gasoline, concrete slurries or paint. according to applicable regulations. Source control BMPs implemented if appropriate_ No contaminants present other than a surface oil film. Grasslgroundcover Grass or groundcover exceeds 18 inches in Grass or groundcover mowed to a height. height no greater than 6 inches. Trees and Shrubs Hazard Any tree or limb of a tree identified as having a No hazard trees in facility. potential to fall and cause property damage or threaten human life. A hazard tree Identified by a qualified arborist must be removed as soon as possible. Damaged Limbs or parts of trees or shrubs that are split or Trees and shrubs with less than 5% broken which affect more than 25% of the total of total foliage with split or broken foliage of the tree or shrub. limbs. Trees or shrubs that have been blown down or No blown down vegetation or knocked over. knocked over vegetation. Trees or shrubs free of injury. Trees or shrubs which are not adequately Tree or shrub in place and supported or are leaning over, causing exposure adequately supported; dead or of the roots. diseased trees removed. 1/9/2009 2W9 Surface Water Design Manual — Appendix A A-16 APPENDIX A MAINTENANCE REQUIREMENTS FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES NO.21—STORMFILTER (CARTRIDGE TYPE) Maintenance Defect or Problem Condition When Maintenance is Needed Results Expected When Component Maintenance is Performed Site Trash and debris Any trash or debris which impairs the function of Trash and debris removed from the facility. facility. Contaminants and Any evidence of contaminants or pollution such Materials removed and disposed of pollution as oils, gasoline, concrete slurries or paint. according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Life cycle System has not been inspected for three years. Facility is re -inspected and any needed maintenance performed. Vault Treatment Sediment on vault Greater than 2 inches of sediment. Vault is free of sediment. Area floor Sediment on top of Greater than % inch of sediment. Vault is free of sediment. cartridges Multiple scum lines Thick or multiple scum lines above top of Cause of plugging corrected, above top of cartridges_ Probably due to plugged canisters or canisters replaced if necessary. cartridges underdrain manifold. Vault Structure Damage to wall, Cracks wider than'�Inch and any evidence of Vault replaced or repaired to design Frame, Bottom, and/or soil particles entering the structure through the specifications. Top Slab cracks, or qualified inspection personnel determines the vault is not structurally sound. Baffles damaged Baffles corroding, cracking warping, and/or Repair or replace baffles to showing signs of failure as determined by specification. maintenanoelinspection person. Filter Media Standing water in 9 inches or greater of static water in the vault for No standing water in vault 24 hours vault more than 24 hours following a rain event and/or after a rain event. overflow occurs frequently. Probably due to plugged filter media, underdrain or outlet pipe. Short circuiting Flows do not properly enter filter cartridges. Flows go through fitter media. Underdrains and SedimerrUdebris Underdrains or dean -outs partially plugged or Underdrains and clean -outs free of Clean -Outs filled with sediment andlor debris. sediment and debris. Inlet/Outlet Pipe Sediment Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment. accumulation Trash and debris Trash and debris accumulated in inlet/outlet No trash or debris in pipes. pipes (includes floatabies and non-floatables). Damaged Cracks wider than at the joint of the No cracks more than Y inch wide at inlet/outiet pipes or any evidence of soil entering the joint of the inlet/oudet pipe. at the joints of the inlet/outlet pipes. Access Manhole CoverAid not in place CoverAid is missing or only partially in place. Manhole access covered. Any open manhole requires Immediate maintenance. Locking mechanism Mechanism cannot be opened by one Mechanism opens with proper tools. not working maintenance person with proper tools. Bolts cannot be seated. Self-locking coverAid does not work. Coverilid difficult to One maintenance person cannot remove Coverilid can be removed and remove coverAid after applying 80 Ibs of lft reinstalled by one maintenance person. Ladder rungs unsafe Missing rungs, misalignment, rust, or cracks. Ladder meets design standards. Allows maintenance person safe access. Large access Damaged or difficult Large access doors or plates cannot be Replace or repair access door so it doors/plate to open opened removed using normal equipment. ran opened as designed_ 1/9/2909 2009 Surface Water Design Manual — Appendix A A-30 APPENDIX A MAINTENANCE REQUIREMENTS FOR FLOW CONTROL, CONVEYANCE, AND WQ FACILITIES NO.21 - STORMFILTER (CARTRIDGE TYPE) Maintenance Defect or problem Condition When Maintenance is Needed Results Expected When Component Maintenance is Performed Gaps, doesn't cover Large access doors not flat and/or access Doors close flat and cover access completely opening not completely covered. opening completely. Lifting Rings missing, Lifting rings not capable of lifting weight of door Lifting rings sufficient to lift or rusted or plate. remove door or plate. 2009 Surface Water Design Manual — Appendix A 1/9/2009 A-31 » If necessary, aggregate can be compacted with a plate compactor to a level no less than the top of the rings or no more than 0.25 inch above the top of the rings (Invisible Structures, 2003). • Grass systems » Spread sand or soil using power brooms, fiat bottom shovels or wide asphalt rakes. A stiff bristle broom can be used for finishing. Lay sod or seed. Grass installation procedures vary by product. Consult manufacturer or supplier for specific grass installation guidelines. • Provide edge constraints along edges that may have vehicle loads (particularly tight radius turning). Gast -in -place or pre -cast concrete is preferred. • Concrete grids require edge restraints along edges in all applications. Plastic grids require restraints when exposed to vehicles. Edge restraints for concrete or plastic grids in such applications should be cast -in -place or pre -cast concrete. 6.3.3 Maintenance Maintenance is an essential element for the successful, long-term application of permeable pavement. Objectives of a comprehensive maintenance program for permeable pavement should include: • Clear, enforceable guidelines for maintenance on private and public right-of-ways. • Education materials describing the materials, function, and proper maintenance of permeable pavements on private property. • Mechanisms to supply new homeowners with educational materials. • Effective sediment and erosion control. • Location of facilities, timing of, and equipment for, maintenance activities. • Methods for testing pavement infiltration rates over time. • Periodic evaluation of maintenance programs and adaptive management to improve effectiveness of maintenance procedures. � 11 • ! 'l.l The following provides maintenance recommendations applicable to all permeable paving surfaces and specific permeable pavement systems. Maintenance recommendations for all facilities • Erosion and introduction of sediment from surrounding land uses should be strictly controlled after construction by amending exposed soil with compost and mulch, planting exposed areas as soon as possible, and armoring outfall areas. • Surrounding landscaped areas should be inspected regularly and possible sediment sources controlled immediately. • Installations can be monitored for adequate or designed minimum infiltration rates by observing drainage immediately after heavier rainstorms for standing water or infiltration tests using ASTM C1701. • Clean permeable pavement surfaces to maintain infiltration capacity at least once or twice annually following recommendations below. • Utility cuts should be backfilled with the same aggregate base used under the permeable paving to allow continued conveyance of stormwater through the base, and to prevent migration of fines from the standard base aggregate to the more open graded permeable base material (Qiniz, 1980). • Ice buildup on permeable pavement is reduced and the surface becomes free and clear more rapidly compared to conventional pavement. For western Washington, deicing and sand application may be reduced or eliminated and the permeable pavement installation should be assessed during winter months and the winter traction program developed from those observations. Vacuum and sweeping frequency will likely be required more often if sand is applied. integrated management practices 197 L6.3,,Permeable Pavement11-.1,177 Maintenance recommendations for specific permeable paving surfaces. Porous asphalt and pervious concrete • Glean surfaces using suction, sweeping with suction or high-pressure wash, and suction (sweeping alone is minimally effective). Hand held pressure washers are effective for cleaning void spaces and appropriate for smaller areas such as sidewalks. • Small utility cuts can be repaired with conventional asphalt or concrete if small batches of permeable material are not available or are too expensive. Permeable pavers • ICPI recommends cleaning if the measured infiltration rate perASTM C1701 falls below 10 inches per hour (Smith, 2011)_ • Use sweeping with suction when surface and debris are dry 1-2 times annually (see next bullet for exception). Apply vacuum to a paver test section and adjust settings to remove all visible sediment without excess uptake of aggregate from paver openings or joints. If necessary, replace No 8, 89 or 9 stone to specified depth within the paver openings. Washing or power washing should not be used to remove debris and sediment in the openings between the pavers (Smith, 2000). • For badly clogged installations, wet the surface and vacuumed aggregate to a depth that removes all visible fine sediment and replace with clean aggregate_ • If necessary, use No 8, 89 or 9 stone for winter traction rather than sand (sand will accelerate clogging). Pavers can be removed individually and replaced when utility work is complete. Replace broken pavers as necessary to prevent structural instability in the surface, • The structure of the top edge of the paver blocks reduces chipping from snowplows. For additional protection, skids on the corner of plow blades are recommended. • For a model maintenance agreement see Permeable Interlocking Concrete Pavements (Smith, 2011). Plastic or concrete grid systems • Remove and replace top course aggregate if clogged with sediment or contaminated (vacuum trucks for stormwater collection basins can be used to remove aggregate). • Remove and replace grid segments where 3 or more adjacent rings are broken or damaged. • Replenish aggregate material in grid as needed. • Snowplows should use skids to elevate blades slightly above the gravel surface to prevent loss of top course aggregate and damage to plastic grid. • For grass installations, use normal turf maintenance procedures except do not aerate. Use very slow release fertilizers if needed. 6.3.4 Permeable Paving Performance Infiltration Initial research indicates that properly designed and maintained permeable pavements can virtually eliminate surface flows for low to higher intensity storms common in the Pacific Northwest, store or significantly attenuate subsurface flows (dependent on underlying soil and aggregate storage design), and provide water quality treatment for nutrients, metals and hydrocarbons. A six -year University of Washington permeable pavement demonstration project found that nearly all water infiltrated various test surfaces (included Eco-Stone, Gravelpave and others) for all observed storms (Brattebo and Booth, 2003). Observed infiltration was high despite minimal maintenance conducted. Initial infiltration rates for properly installed permeable pavement systems are high. Infiltration rates for in- service surfaces decline to varying degrees depending on numerous factors including initial design and installation, sediment loads, and maintenance. 198 Integrated management practices