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Home My WebLink AboutF_Fire Station 15_Technical Information Report_180215.pdf Fire Station 15 1404 N 30th St, Renton, WA Technical Information Report November 10, 2017; Revised February 12, 2018 Prepared by: LPD Engineering, PLLC 1932 1st Avenue Suite 201 Seattle, WA 98101 Contact: Laurie J. Pfarr, P.E. (206) 725-1211 Prepared for: Schreiber Starling Whitehead Architects 901 5th Avenue #3100 Seattle, WA 98164 Contact: Keith Schreiber, AIA (206) 682-8300 DEVELOPMENT ENGINEERING IFitz-James 02/15/2018 SURFACE WATER UTILITY rstraka 02/15/2018 Fire Station 15 Technical Information Report Submitted: November 10, 2017; Revised: February 12, 2018 FIRE STATION 15 TABLE OF CONTENTS Section 1 – Project Overview ......................................................................................................................................... 1 Section 2 – Conditions and Requirements Summary .............................................................................................. 2 Section 3 – Offsite Analysis .............................................................................................................................................. 4 Section 4 – Flow Control, Low Impact Development (LID), and Water Quality Facility Analysis and Design ...................................................................................................................................................................................... 7 Section 5 – Conveyance Systems Analysis and Design ......................................................................................... 12 Section 6 – Special Reports and Studies ..................................................................................................................... 12 Section 7 – Other Permits .............................................................................................................................................. 12 Section 8 – CSWPPP Analysis and Design ................................................................................................................ 12 Section 9 – Bond Quantities, Facility Summaries, and Declaration of Covenant ......................................... 13 Section 10 – Operations and Maintenance Manual ................................................................................................ 13 FIGURES Figure 1: TIR Worksheet Figure 2: Vicinity Map Figure 3A: Existing Conditions Figure 3B: Proposed Conditions Figure 4: Soils Map Figure 5: Downstream Drainage Course APPENDICES Appendix A – Design Drawings Appendix B - Design Calculations Appendix C - Stormwater Pollution Prevention and Spill Plan Report Appendix D – Operations and Maintenance Manual Appendix E – Declaration of Covenant Appendix F – Downstream Analysis Photos Appendix G – Geotechnical Report and Supplemental Memorandum Page 1 Fire Station 15 Technical Information Report Submitted: November 10, 2017; Revised: February 12, 2018 FIRE STATION 15 TECHNICAL INFORMATION REPORT SUBMITTED: NOVEMBER 10, 2017; REVISED: FEBRUARY 12, 2018 SECTION 1 – PROJECT OVERVIEW This Technical Information Report (TIR) is for the construction the new Fire Station 15 for the City of Renton. Refer to Figure 1: TIR Worksheet for basic site information. The project is west of I-405, located at 1404 N 30th Street on parcel #3342103245. The site is in Section 32, Township 24, Range 5, Willamette Meridian. Refer to Figure 2- Vicinity Map. The City of Renton has adopted the 2016 King County Surface Water Design Manual (KCSWDM) with the City’s 2016 Surface Water Design Manual Amendment (RSWDMA). According to Figure 1.1.2.A of the RSWDMA, Flow Chart for Determining Type of Drainage Review Required, the project is subject to a “Full Drainage Review” because the project results in greater than 2,000 SF of new plus replaced impervious surface, and it is not a large project or single family residential project. Per the “Full Drainage Review” requirements in Table 1.1.2.A, the TIR addresses Core Requirements #1-9 and Special Requirements #1-5 of the 2016 RSWDMA. The current property is proposed to be subdivided into two lots. The northern lot will be for the development of a new water storage reservoir serving the 320-pressure zone. The project in the northern lot will be on a similar timeline for design and construction and will be permitted separately. The southern lot will be the extent of the proposed project improvements addressed in this report. Please note in the documents that due to the timing of the Reservoir construction that portion of the work is indicated by others as the Reservoir construction will utilize this area as construction access and laydown. These areas will be constructed to the proposed improvements by Reservoir Contractor prior to completion of their project. Existing Site The total existing parcel area is 47,538 SF (1.09 acres). The project limit of work within the southernmost subdivided lot totaling 31,173 SF (0.72 acre). The site and bounded by two gas stations to the east and west, single-family residences to the north, and N 30th St to the south. The property is located in the Kennydale neighborhood on a vacant, city-owned parcel. See Figure 3A – Existing Conditions. Topographically the site generally slopes downward from northeast to southwest, a vertical elevation change of 12.5 feet. According to the USDA Natural Resources Conservation Service, the site soils in the project area are mapped as Indianola loamy sand (InC) with 5 to 15 percent slopes. Refer to Figure 4 – Soils Map. HWA GeoSciences, Inc. prepared a study for the project site dated December 21, 2017. The field investigation included three boring samples and one Pilot Infiltration Test. In general, the borings indicated one foot of topsoil underlain with recessional outwash to approximately 5-feet to 7- feet in depth. Underneath the recessional outwash is weathered till soils consisting of medium dense silty sand. In the geotechnical engineer’s study, it was determined that shallow BMP facilities would not be feasible for infiltration. Deep infiltration filtration facilities are feasible if the upper fine-grained material is over-excavated approximately 7 feet below grade to expose the native clean soils that have an infiltration rate of 1.1 inches per hour. Page 2 Fire Station 15 Technical Information Report Submitted: November 10, 2017; Revised: February 12, 2018 A survey of the site has been prepared by Duane Hurtmant & Associates, Inc. on October 21st, 2016. According to the survey, there are no existing drainage facilities on the property. It appears the majority of the stormwater runoff from the project site sheet flows southwest towards an existing inlet within in N 30th St. There is a 12-inch public storm main flowing west within the north portion of N 30th Street. The site is located in the East Lake Washington drainage basin. According to the City of Renton GIS maps, the site is located within a Wellhead Protection Area Zone 2. Along the eastern property line of the site, a relatively small area has been designated as a regulated slope (>15% and ≤ 25%). There do not appear to be any other critical areas on the site. Proposed Site Improvements Proposed improvements include a new fire station with 11 standard parking stalls on-site and one ADA stall with ADA accessible walkways to the front entrance. An asphalt drive access will be constructed along the west side of the property to be shared with the northern subdivided water reservoir lot. A second drive on the eastern portion of the property that will be for fire truck exit only out of the 2-bay garage. The parking lot north of the building will be constructed as a permeable pavement facility and runoff will infiltrate through the existing soils beneath. Runoff from a portion of the roof, northern drive entrance, and some walkways will be collected by a bioretention facility with an infiltrating gravel basin. The stormwater overflow will then route to the proposed shallow detention facility along the south property line. The asphalt drive access and south driveway will be treated with StormFilter cartridges before discharging to the detention facility. Controlled flows form the detention facility will then discharge to the existing public system along N 30th Street. Refer to Section 4 – Flow Control and Water Quality Analysis and Design for further information on the storm drainage design. Also refer to Figure 3B – Proposed Conditions. Improvements will be made to the frontage along N 30th Street to accommodate the two proposed drive entrances per coordination with the City of Renton.. An 11-foot dedication along the site frontage has been requested by the City to allow for future right-of-way (ROW) expansion to N 30th Street. SECTION 2 – CONDITIONS AND REQUIREMENTS SUMMARY This section addresses the Core Requirements (Section 1.2) and Special Requirements (Section 1.3) requirements set forth by 2016 RSWDMA. Core Requirement 1 - Discharge at the Natural Location (1.2.1) The proposed conditions will maintain the natural drainage patterns within its basin. All stormwater runoff will be routed to the existing catch basin inlet within N 30th Street discharging to the 12-inch public storm main. Core Requirement 2 - Off-site Analysis (1.2.2) An offsite analysis is required for this project and can be referred to in Section 3 below. A field investigation and assessment has been conducted by LPD dated November 4th, 2017. Core Requirement 3 – Flow Control (1.2.3) Per the City of Renton Flow Control Application Map, Reference 15-A in the RSWDMA., the project site is located within a Peak Rate Flow Control Standard (Existing Site Conditions) area. Therefore, flow control facilities must be provided to match the existing site’s peak discharge rates for the 2- year, Page 3 Fire Station 15 Technical Information Report Submitted: November 10, 2017; Revised: February 12, 2018 10-year, and 100- year return periods at the point of discharge from the site. Per the RSWDMA, flow control facilities must mitigate the runoff from the target surfaces which include new impervious surfaces and new pervious surfaces not fully dispersed. For further information regarding the flow control design, refer to Section 4 of this report. Core Requirement 4 - Conveyance System (1.2.4) A conveyance design analysis for the project has been completed and is included within Section 5 of this Report. Core Requirement 5 - Erosion and Sedimentation Control (1.2.5) A Temporary Erosion and Sediment Control (TESC) plan for the project is included with this submittal. The TESC plan will be considered the minimum for anticipated site conditions. The Contractor will be responsible for implementing all TESC measures and upgrading as necessary. The TESC facilities will be in place prior to clearing, grubbing, or construction of proposed improvements. Core Requirement 6 - Maintenance and Operations (1.2.6) The maintenance and operations guidelines for all of the proposed stormwater facilities have been included in Appendix D. Core Requirement 7 – Financial Guarantees and Liability (1.2.7) Financial guarantees and liability are not anticipated to be required since the Owner is a public agency. Core Requirement 8 – Water Quality (1.2.8) The project proposes more than 5,000 SF of pollutant generating impervious surface (PGIS) and therefore requires the project to provide water quality treatment. For further information regarding the water quality design requirements, refer to Section 4 of this report. Core Requirement 9 – On-site BMP’s (1.2.9) The project is required to provide onsite flow control best management practices (BMP’s) to mitigate the impacts of stormwater runoff generated by the new plus replaced impervious surface to the maximum extent feasible. Per section 1.2.9.2 of the 2016 RSWDMA, the project is larger than 22,000 SF; therefore, the project will apply the large lot BMP requirements. For further information regarding the on-site BMP’s, refer to Section 4 of this report. Special Requirement 1 – Other Adopted Area-Specific Requirements (1.3.1) • Master Drainage Plans (MDPs) – Project is not within an area covered by an approved Master Drainage Plan. • Basin Plans (BPs) – The project is located in the East Lake Washington drainage basin. The Renton Municipal Code does not provide any more stringent flow control or water quality requirements than that of the current code. • Salmon Conservation Plans (SCPs) – The applicable SCP is the Water Resource Inventory Area (WRIA) 8 for the Lake Washington/Cedar/Sammamish Watershed. Within the large watershed, our project is in the Lake Washington. The SCP does not appear to have stormwater management requirements more stringent than Renton Municipal Code. Page 4 Fire Station 15 Technical Information Report Submitted: November 10, 2017; Revised: February 12, 2018 • Stormwater Compliance Plans (SWCPs) – The project is not within an area governed by a SWCP. • Flood Hazard Reduction Plans (FHRPs) –The project site is not within a designated flood hazard area. • Shared Facility Drainage Plan (SFDPs) – The proposed project is not within an area with a SFDP. Special Requirement 2 – Flood Hazard Area Delineation (1.3.2) The project site is not located within or adjacent to a designated flood hazard area Special Requirement 3 – Flood Protection Facilities (1.3.3) The project does not rely on an existing flood protection facility, nor will a new flood protection facility be constructed; therefore, this requirement is not applicable. Special Requirement 4 – Source Control (1.3.4) In the proposed conditions, there will be no applicable activities matching those listed within the 2016 King County Stormwater Pollution Prevention Manual (KCSPPM) that will require the use of source control measures. Special Requirement 5 – Oil Control (1.3.5) The project will not have high-use site characteristics, nor is it an existing high-use site. Special Requirement 6 – Aquifer Protection Area (1.3.6) Per the city of Renton Aquifer Protection Area (APA) map, the project site is within Zone 2. Per the geotechnical report the infiltrative soils on-site have a cation exchange capacity greater than 5, an organic content greater than 0.5%, and are composed of less than 25% gravel by weight with at least 75% of the soil passing the #4 sieve and meet the gradation requirements of Section 1.2.8 of the RSWDMA. Therefore; the existing soils meet the soil properties required within the groundwater protection areas and allow the project to be exempt from Core Requirement #8 per 1.2.8 Exemption #4 Soil Treatment Exemption. SECTION 3 – OFFSITE ANALYSIS The following is the Level 1 downstream analysis for the proposed project. Refer to Figure 5 - Downstream Drainage Map. The following resources have been reviewed for the project area: Study Area Definition and Maps Basin Summary King County’s Watershed Map locates the project site in the East Lake Washington – Renton drainage basin. Floodway Map A FEMA flood insurance rate map (53033C0664F) is included in Appendix B, illustrating the FEMA flood zone designations for the site. The site is located within zone X, which are areas outside the 0.2% annual chance floodplain. Page 5 Fire Station 15 Technical Information Report Submitted: November 10, 2017; Revised: February 12, 2018 Sensitive Areas The sensitive areas within one-mile upstream and downstream of the subject property were examined using the King County iMAP application. According to iMAP, the following are the sensitive area designations for the project site and within one mile downstream of the site:  SAO Erosion Hazard – The project site is not located within an erosion hazard area. There is an erosion hazard area identified on iMAP approximately 900 LF east of the site which is not downstream of the site.  SAO Seismic Hazard – There are no seismic hazard areas on the site on within one mile of the site.  SAO Landslide Hazard – There are no landslide hazard areas on the site on within one mile of the site.  SAO Coal Mine –There are no known coal mines on the site or within one mile of the site.  SAO Stream – There are no sensitive streams located within the project site or within a mile downstream of the project site.  SAO Wetland – There are no wetlands located within the project site or within one mile downstream of the project site.  Groundwater Contamination – The project area is not located within an area designated as being susceptible to groundwater contamination.  Sole Source Aquifer – The project area is not within a sole source aquifer area.  Channel Migration Hazard – There are no channel migration hazards for the site. Topographic Map The Topographic information for the project area is shown on the Design Drawings in Appendix A of this report. Drainage Complaints According to King County’s iMap program, there have been no drainage complaints within the last 10 years within the project site, upstream area, or downstream area. King County Soils Survey As stated previously, according to the USDA Natural Resources Conservation Service, the site soils in the area of proposed work are mapped as Indianola loamy sand (InC). Refer to Figure 4: Soils Map. Migrating River Studies According to King County’s iMAP program, the project site is not located within a channel migration hazard. 303d List of Polluted Waters According to Washington State Department of Ecology’s Water Quality Assessment map, the project site does not contain any polluted water. The southeast area of Lake Washington, the immediate receiving water for the downstream system, is designated as a Category 5-303d water for bacteria (Listing ID 12193). There are no Water Quality Improvement Projects identified as part of the 303d listing. Page 6 Fire Station 15 Technical Information Report Submitted: November 10, 2017; Revised: February 12, 2018 Water Quality Problems According to King County’s iMAP program, the project site is not within a designated King County water quality problem area. Developed Site Hydrology Please refer to Section 1- Project Overview and the Flow Control System section below in this report for a description of the proposed hydrology. Field Inspection A field inspection was conducted by LPD on November 4th, 2017. Refer to Drainage System Description and Problem Descriptions below for information about the existing conditions and downstream analysis. Drainage System Description and Problem Descriptions The following downstream analysis has been prepared using City of Renton Surface Water Network Map, topographical survey, and a site visit dated November 4th, 2017. The weather at time of inspection was dry but cloudy with an average temperature of 42º Fahrenheit. As stated previously, there are no existing drainage facilities on the property. It appears the majority of the stormwater runoff from the project site sheet flows southwest towards existing inlet within in N 30th Street. Refer to Figure 5 – Downstream Drainage Course for the continuation of the downstream flow path and Appendix F for photos taken during the visit. The remaining downstream course is as follows: 1. The flow continues west within the 12-inch system along N 30th Street for approximately 1,000 feet. 2. The system continues west through 18-inch line in N 30th Street, between Park Ave N and Burnett Ave N, about 300 feet before crossing the ¼-mile point downstream from the site. 3. Stormwater discharges into existing catch basin located at the intersection of N 30th Street and Burnett Ave N. Flow continues north through 18-inch pipe to an existing catch basin near the intersection of Burnett Ave N and N 33rd Street. 4. A 24-inch storm line exits the existing catch basin and continues north for about 530 feet to a catch basin at the intersection of Burnett Ave N and N 34th Street. 5. Flow continues west before discharging to existing catch basin within Lake Washington Blvd N. 6. A 24-inch storm line exits the catch basin and continues southwest for about 120 feet. 7. The system continues west through 24-inch line, eventually outfalling to Lake Washington. Based upon our field review of the system, there was not evident problem areas or areas of concern. Mitigation of Existing or Potential Problems As previously mentioned, there are no sensitive or problem areas near or around the site. Refer to Study Area Definition and Maps for more information. Page 7 Fire Station 15 Technical Information Report Submitted: November 10, 2017; Revised: February 12, 2018 SECTION 4 – FLOW CONTROL, LOW IMPACT DEVELOPMENT (LID), AND WATER QUALITY FACILITY ANALYSIS AND DESIGN Existing Site Hydrology Please refer to Section 1- Project Overview and Section 3- Off-site Analysis of this report for a description of the existing hydrology. Developed Site Hydrology Please refer to Section 1- Project Overview and the Flow Control System section below in this report for a description of the proposed hydrology. Performance Standards Please refer to Section 2- Conditions and Requirements Summary, Section 5 – Conveyance Systems Analysis, and the Flow Control System, and Water Quality sections of this report for a description of the required standards applicable to this report. Flow Control BMPs have been applied in accordance with Section 1.2.9 of the RSWDMA. Refer to Figure 3B – Proposed Conditions and Area Summary spreadsheet for the calculated impervious coverage and area calculations for BMP implementation. The project site proposed more than 2,000 SF of new plus replaced impervious surfaces which will require an evaluation of BMP feasibility for all target surfaces. The project site is larger than 22,000 SF, therefore, the feasibility of on-site BMPs must be evaluated for each BMP listed in Section 1.2.9.2.2 of the RSWDMA: 1. Full dispersion is not feasible to be used as BMP due to the limited site and vegetative flow path downstream of the target surfaces. 2. Full infiltration of roof runoff and runoff from other target surfaces is not feasible according to Section 5.2 of the RSWDMA. Per the geotechnical report, the soils on-site consist of silty sand and are not as permeable as the required medium/coarse sands targeted for full infiltration. Based on the test results, the site soils have a long-term infiltration rate of 1.1 inches/hour. 3. Since the target impervious surfaces could not be mitigated by Requirements 1 and 2 above, the following has been implemented where feasible and receptor soils are available: • Limited Infiltration: Limited infiltration will be applied to the north section of the roof, some walkways, and the north parking lot. Per Section 1.2.8 Exemption #4 of the RSWDMA, the soil beneath the permeable pavement and bioretention facility meet the properties required for groundwater protection to reduce the risk of groundwater contamination from stormwater runoff. These areas will be over-excavated to reach the existing soils conducive to infiltration. • Bioretention: Approximately 6,935 SF of impervious area will be directed to a bioretention facility west of the proposed building. Per the King County Rainfall Regions map, the project site falls within the rainfall region SeaTac 1.0. In outwash soils, the bioretention volume is based on 0.1 inches of equivalent storage depth by the square footage of the target surface area serve. Therefore, the required storage volume of the bioretention pond is 58 CF of required storage. The project proposes a 6-inch ponding bioretention cell with a total designed volume of 178 CF. The bioretention area consists of 18-inches of bioretention soil mix underlain by 12-inches of drain rock. This facility is too shallow to reach the infiltrative native soil. Per Section C.2.6, since an underdrain is not permitted by the City to meet Core Requirement #9, the existing soil below the bioretention area will be over excavated and a 3’ wide by 28’ long gravel infiltration basin will be installed below the 12-inch drain rock. The bottom of the infiltration basin is to be Page 8 Fire Station 15 Technical Information Report Submitted: November 10, 2017; Revised: February 12, 2018 installed approximately 7 feet below existing grade to reach native soils that are conducive to infiltration. • Permeable Pavement: Permeable concrete pavement has been proposed for the parking area located north of the proposed fire station. The permeable pavement section is designed to have pervious paving, over a choker coarse, a minimum of 36-inches of recharge bed material that is extended to the existing subgrade receptor soil. Per coordination with the City and additional testing from the geotechnical engineer, the existing soil properties of the receptor soils meet the criteria per Section 1.2.8 Exemption #4 of the RSWDMA for projects located within the groundwater protection areas and is suitable for the proposed permeable pavement infiltration and water quality facility. The total permeable pavement area proposed for the project is approximately 4,170 SF. 4. Basic dispersion is not feasible to be used as BMP per Section C.2.4 of the RSWDMA due to the limited vegetative flow path downstream of the target surfaces. 5. The proposed project site will have an impervious coverage greater than 65% on the buildable portion of the site. Therefore, the site is categorized under the Large Lot BMP Requirements and on-site BMPs are required to be applied to at least 20% of the target impervious surfaces. Based upon the 20% of the proposed approximately 23,010 SF of new plus replaced impervious surface , the total area required to be mitigated by BMP facilities is 4,602 SF. Currently the project is proposing to mitigate a total of 11,105 square feet which is 48.2%. Flow Control System As stated in Section 3 of this report, the project site is located within a Peak Rate Flow Control Standard (Existing Site Conditions) area. Therefore, flow control facilities must be provided to match the existing site conditions peak discharge rates for the 2- year, 10-year, and 100- year return periods at the point of discharge. Based on the RSWDMA definition, the ‘existing site conditions’ are those that existed at the site prior to May 1979 as determined from aerial photographs, unless a drainage plan for land cover changes has been approved by the city since May 1979 as a part of a city permit or approval. Based on the city’s records, there have been no drainage plans for permitted land cover changes by the City since 1979. Based on available historical aerials from King County’s map vault, a 1954 and 1965 map show two residential building with a gravel driveway and grassed-landscape on-site. Based on Renton’s record documents, the previous owners sold the deed of the property to the City in 2001. In the year 2005 the house was demolished according to Google aerial maps. Currently, the site is a grassed vacant lot with a few large trees. For the modeled pre-developed conditions, instead of calculating the amount of existing impervious area constructed before 1979 based on aerial photos, the redeveloped area will be considered as “grass” for conservative flow calculations. Please refer to Figure 3A – Existing Conditions for the referenced aerial images has been included in Appendix B. For the stormwater threshold analysis, MGSFlood was used to model the pre-developed and developed conditions within the project site area. A summary of areas for the site can be found in Appendix B of this report and are also referred in Figure 3B – Proposed Conditions. The project proposes approximately 23,010 SF of new plus replaced impervious surface. The majority of the site which includes the asphalt access drive, walkways, and roof will be modeled to route directly to the detention facility and are considered to be 100% impervious surfaces. Walkway and driveway improvements from the ROW will be included as a target surface in the model and are considered to be 100% impervious. The permeable pavement facility will be modeled using the permeable pavement element in MGSFlood. The bioretention area includes an infiltration gravel basin at the bottom that was Page 9 Fire Station 15 Technical Information Report Submitted: November 10, 2017; Revised: February 12, 2018 modeled using the infiltration trench element. The surfaces considered pollution-generating will be treated by water quality facilities preceding the detention system. For more information, see the Water Quality section below in this report. The target surfaces within the 11-foot dedication area associated with the ROW as well as target surfaces within ROW cannot drain by gravity to a water quality facility nor a detention facility and will be modeled as target surfaces bypassing the detention facility in the developed conditions. The bypass areas on site will sheet flow to the northern gutter line along N 30th Street into the existing inlet where the on-site proposed drainage system will also connect to before discharging into the existing 12-inch public main. The following conditions were evaluated to meet the requirements presented in section 1.2.3.2.E of the 2017 RSWDMA for mitigation of target surfaces that bypass the detention facility: 1. Point of convergence is within a quarter-mile downstream of the facility’s project site discharge point. 2. The increase in the existing site conditions 100-year peak discharge from the area of bypassed target surfaces does not exceed 0.4cfs. Refer to the MGSFlood output for the peak flow rates for the pre-developed and developed bypass areas in Appendix B of this report. 3. The bypass target surfaces are not anticipated to create any adverse impacts to the existing drainage system. 4. Water quality facilities were deemed infeasible for the target bypass areas. See the Water Quality section below in this report for additional information. 5. The target bypass areas were included in the MGSFlood model so the net effect at the point of convergence downstream is the same with or without the bypass areas. The MGSFlood output for the peak flow rates for the developed project area are included in the following Table 1, and in Appendix B of this report. Table 1 – Net Peak Flow Rates for Discharge from Project Work Area Peak Runoff Rates for Project Work Area Storm Event Existing Conditions Proposed Conditions Delta 2-yr 0.069 cfs 0.058 cfs 0.011 cfs 10-yr 0.174 cfs 0.162 cfs 0.012 cfs 100-yr 0.375 cfs 0.336 cfs 0.039 cfs The required storage volume of detention facility totals 625 CF of live storage. The product being specified as the detention system is an ADS StormTech Chamber System which is not specifically included as a detention method in the 2016 KCSWDM. The system was chosen due to site constraints requiring a shallow detention facility. An adjustment request is included with the project submittal for the use of this Stormtech Chamber System for approval from the City. The detention facility will consist of two rows of chambers surrounded with a total dimension of 40.5-feet long by 12.1-feet wide and 3.5-feet deep (3-feet deep of live storage). A 6-inch layer of granular well-graded soil/aggregate mixture backfill will cover all sides of the facility. The facility will outflow to a flow control structure located west of the facility to restrict the flows entering the existing public storm system. Page 10 Fire Station 15 Technical Information Report Submitted: November 10, 2017; Revised: February 12, 2018 Water Quality System The project proposes approximately 12,900 SF of pollution-generating impervious surfaces and therefore requires the project to provide water quality treatment. Per the geotechnical supplementary evaluation of the existing soils, the first 2-feet of soil into the receptor layer below the infiltration facilities meet the groundwater protection criteria stated the Soil Treatment exemption per Section 1.2.8 Exemption #4. A total of 5,315 SF of the pollution-generating impervious surface routing to infiltration facilities will be exempt from water quality treatment. This includes the northern pervious pavement parking lot as well as the drive apron on the north side of the proposed building which is routed to the infiltrating bioretention area. The northern parking lot exempt from water quality treatment will be constructed with a heavy-duty concrete permeable pavement infiltration facility designed for fire truck loading. Stormwater runoff will percolate through the permeable surface layer into the free-draining base and storage reservoir. The total depth of the permeable pavement section deep enough to reach the existing soils that meet the groundwater protection criteria. The infiltrative native subgrade has a design infiltration rate of 1.1 inches per hour per the geotechnical engineer’s recommendation. As stated previously the permeable pavement facility is included in the MGSFlood output in Appendix B and has determined the facility will to infiltrate 100% of the of the PGIS runoff. The drive apron exempt from water quality treatment is collected by a bioretention facility with an infiltrating gravel basin that discharges to the existing soils that meet the groundwater protection criteria and is conducive to infiltration. As stated previously the bioretention and gravel basin facility is included in the MGSFlood output in Appendix B and has determined the facility will to infiltrate 91.3% of the of the PGIS runoff. The excess runoff is designed to overflow into the downstream detention facility. The 7,585 SF of PGIS not routed to the proposed infiltration facilities will not meet the exemptions listed in Section 1.2.8 and will be required to be treated for water quality. Per Section 1.2.8.1, the project site is located in a Basic WQ Treatment Area. However, the project is categorized a Commercial Land Use project and requires commercial building permit; therefore triggering Enhanced Basic Water Quality Treatment. Due to site limitations, per Section 1.2.8.1 an exception to reduce from Enhanced Basic Water Quality Measures back to Basic Water Quality is being pursued based upon meeting the following Criteria: a) The various options for Enhanced Treatment listed in Section 6.1.2 of the RSWDMA were evaluated for feasibility: 1. Enhanced Basic Option 1 – Large Filter Sand: This option was deemed infeasible because the runoff from the facility cannot be routed via a gravity system through the required detention facility and into the existing shallow drainage system within the ROW after reasonable efforts to grade. These systems would require a pumped system which is undesirable thus infeasible. 2. Enhanced Basic Option 2 – Stormwater Wetland: This option was deemed infeasible due to the following reasons:  Not enough available site area There is less than 100 sf that is not within 5 feet of the building or detention facility or encumbered by utilities thus the available area is less than what would be required for the use of a stormwater wetland.  Additionally, there is no natural water supply during dry seasons, these areas would need to be fully irrigated to be maintained which is not encouraged as an environmentally beneficial practice. Page 11 Fire Station 15 Technical Information Report Submitted: November 10, 2017; Revised: February 12, 2018 3. Enhanced Basic Option 3 – Two-Facility Treatment Train: Each off the paired facilities were deemed infeasible due to either requiring an unavailable amount of site or because the runoff from the facility cannot be routed via a gravity system through the two treatment train through required detention facility and into the existing shallow drainage system within the ROW after reasonable efforts to grade. These systems would require a pumped system which is undesirable thus infeasible. 4. Enhanced Basic Option 4 – Bioretention: Deemed infeasible for the southern portion of the site as there is not enough available site area. There is less than 100 sf that is not within 5 feet of the building or detention facility or encumbered by utilities thus the available area is less than what would be required for the use bioretention. Additionally, a bioretention facility in this area due to the required grading and depth of the system could not gravity drain through required detention facility and into the existing shallow drainage system within the ROW after reasonable efforts to grade. These systems would require a pumped system which is undesirable thus infeasible. 5. Enhanced Basic Option 5 – Proprietary Facility: A Filterra system was sized and analyzed for the south side of the site and determined infeasible due to a difference in elevation of 4.3 feet from rim to outlet. Stormwater could not gravity drain from the Filterra through required detention facility and into the existing shallow drainage system within the ROW after reasonable efforts to grade. These systems would require a pumped system which is undesirable thus infeasible. 6. Enhanced Basic Option 6 – WSDOT WQ Facilities: Each system was deemed infeasible as follows:  Media Filter Drain (MFD) does not apply to project because no highway side slopes, ditches, or other linear depressions are proposed.  Compost-Amended Vegetated Filter Strips (CAVFS) are infeasible because no roadside embankments are proposed.  Compost-Amended Biofiltration Swales (CABS) are infeasible because the minimum swale length cannot be met for the site b) There are no leachable, heavy metals proposed for use on site. c) A covenant will be filed that will prohibit use of leachable, heavy metals on the site. d) 100% of the runoff comes from areas that have a ADT of less than 100 vehicles and will not be involved with vehicle repair or sales. Based upon the preceding information, it is assumed that Basic Water Quality facilities will be allowed and implemented for this project. Stormwater runoff from the asphalt access drive and the fire truck driveway apron on the south side of the proposed building will each be treated by two (2) separate Stormfilter catch basin systems. A Stormfilter analysis has been conducted by Contech Stormwater Solutions and is included in Appendix B of this report, using the project’s flow rates calculated in MGSFlood stormwater modeling. The StormFilter structure will have ZPG media (zeolite, perlite, granular activated carbon). Per Section 6.2.1 of the 2017 COR SWDM, the Stormfilter design flow when the facility precedes detention is the flow at which as a minimum will treat 91% of the total runoff. The water quality design flow rate is the peak 15 minute flow rate as calculated using an approved continuous runoff model. The resulting size of StormFilter Structures was two (2) 18-inch cartridges in each catch basin structure near each surface, upstream of the detention system. The MGSFlood output for the water quality analysis and the calculations by Contech for the StormFilter have been provided in Appendix B of this report. Page 12 Fire Station 15 Technical Information Report Submitted: November 10, 2017; Revised: February 12, 2018 SECTION 5 – CONVEYANCE SYSTEMS ANALYSIS AND DESIGN The proposed conveyance system will be designed to convey the 25-year peak flow rate of the developed site. The system is allowed to overtop during the 100-year peak flow provided that it does not create or aggravate a severe flooding problem. The entire project site was considered 100% impervious for conservative calculations. A conveyance analysis was performed for one pipe run. The 12-inch storm line is the ultimate discharge point, receiving flow from the entire site at a minimum 0.5% slope. The tributary flows were calculated using MGS Flood with the 158-year, 5-minute time series and were compared to the full flow capacity of the conveyance pipe calculated by the Manning’s equation. The pipe analyzed was determined to have adequate capacity to convey the 25-year peak flow for the tributary area. Attached is the complete output from MGS Flood and Conveyance Analysis Spreadsheet. SECTION 6 – SPECIAL REPORTS AND STUDIES A geotechnical report prepared by HWA GeoSciences Inc. dated December 21, 2017 and a supplemental memorandum dated January 29th, 2018 has been provided under separate cover. SECTION 7 – OTHER PERMITS An NPDES permit from the Washington State Department of Ecology will not be required for the project disturbs less than one (1) acre of land. There are no additional permits required from other agencies for this project. SECTION 8 – CSWPPP ANALYSIS AND DESIGN An Erosion Sediment Control (ESC) plan has been prepared for the project and is included within the Design Drawings included in Appendix A of this report. The ESC plan includes a temporary sediment settling tank. A minimum volume was calculated using the methodology from 2017 RSWDMA, with the 2-year developed flow rate from MGSFlood. A volume equivalent sediment trap was calculated to find the necessary volume for a sediment tank for this project. A copy of the sediment trap sizing calculations worksheets used for this exercise is attached in Appendix B. In addition to the sediment settling tank, plans include a sediment trap upstream from the temporary tank. The construction storm water pollution prevention plan (CSWPPP) consists of the site preparation plan provided on plan sheets C1.01-C1.2 and a Stormwater Pollution Prevention and Spill (SWPPS) plan provided in Appendix C. The Contractor will be responsible for implementing all TESC measures and upgrading as necessary. The TESC facilities will be in place prior to any clearing, grubbing or construction. Anticipated minimum ESC and stormwater pollution prevention measures are as follows: • Mark Clearing Limits/Minimize Clearing – Clearing limits will be defined by erosion control components and areas of proposed grading. Clearing will be minimized to the maximum extent practicable. No existing trees will be removed. • Minimized Sediment Tracked Offsite – A stabilized construction entrance for vehicle access to minimize the tracking of public roads. The temporary construction access is shown on the ESC Page 13 Fire Station 15 Technical Information Report Submitted: November 10, 2017; Revised: February 12, 2018 plan. If necessary, sediment shall be removed from roads by shoveling or pickup sweeping and shall be transported to a controlled sediment disposal area. • Install Sediment Controls – Runoff from disturbed areas must pass through a sediment control measures to prevent the transport of sediment downstream until the disturbed area is fully stabilized. Sediment will be controlled using perimeter siltation control which includes silt fencing. In addition, catch basin inlet protection will be installed on any existing catch basin within and surrounding the project area. • Stabilize Exposed Soils –It is possible that some of the earthwork and grading may occur in wet weather conditions. The site must be stabilized and no soils will be allowed to remain unstabilized for more than two days between October 1 and April 30. From May 1 through September 30, cover measures must be installed to protect disturbed areas that will remain unworked for seven days or more. By October 8, seed all areas that will remain unworked from October 1 through April 30. Mulch all seeded areas. Exposed slopes will be protected by DOE-approved coverage measures, such as mulching, nets and blankets, plastic covering, seeding, and sodding per Section C.3 of the KCSWDM will be used to stabilize onsite soils during construction. See Erosion and Sedimentation Control Notes on the plans in Appendix A • Control Pollutants – Sediment is the only pollutant expected from the proposed project. Limiting the duration of disturbance of the site soils provides the first level of protection for pollution control, and perimeter measures on the edges of the disturbed areas will mitigate the remaining pollutants. • Control De-watering – De-watering is not expected to be required. If perched groundwater is encountered and de-watering is necessary, a temporary pump will be used to remove water from the trenches. Pumped water will be routed to perimeter undisturbed areas or other approved location prior to discharge from the project site. • Maintain BMPs – The BMPs will be maintained regularly in accordance with the Erosion and Sedimentation Control Plan and Notes. • Manage the Project – The Contractor will maintain a daily presence on the site and will assign a contact person for erosion and sedimentation control issues. SECTION 9 – BOND QUANTITIES, FACILITY SUMMARIES, AND DECLARATION OF COVENANT Public Agencies are not required to bond with the City, however; it is our understanding that the Bond Quantities Worksheet is also utilized in estimating review fees. The bond quantity worksheet has been included under a separate cover. A Facility Summary and Declaration of Covenant will be provided supplementary to this report. SECTION 10 – OPERATIONS AND MAINTENANCE MANUAL The operations and maintenance guidelines from the 2016 King County Surface Water Design Manual Appendix A has been included in Appendix D of this report. Fire Station 15 Technical Information Report November 8, 2017; Revised January 25, 2018 FIGURES Figure 1: TIR Worksheet Figure 2: Vicinity Map Figure 3A: Existing Conditions Figure 3B: Proposed Conditions Figure 4: Soils Map Figure 5: Downstream Drainage Course engineering pllc 1932 1st Ave, Suite 201, Seattle, WA 98101 p. 206.725.1211 f. 206.973.5344 www.lpdengineering.com FIRE STATION 15 2VICINITY MAP 1932 1st Ave,Suite 201,Seattle, WA 98101p. 206.725.1211f. 206.973.5344www.lpdengineering.comengineering pllc2017 LPD Engineering PLLC©FIRE STATION 153AEXISTING CONDITIONS 1932 1st Ave,Suite 201,Seattle, WA 98101p. 206.725.1211f. 206.973.5344www.lpdengineering.comengineering pllc2017 LPD Engineering PLLC©FIRE STATION 153BPROPOSED CONDITIONS engineering pllc 1932 1st Ave, Suite 201, Seattle, WA 981041 p. 206.725.1211 f. 206.973.5344 www.lpdengineering.com FIRE STATION 15 4SOILS MAP MAP UNIT SYMBOL KING COUNTY AREA, WASHINGTON (WA633) InC Indianola Loamy Sand, 5% to 15% slopes MAP UNIT NAME PROPERTY AREA engineering pllc2017 LPD Engineering PLLC©FIRE STATION 1551932 1st Ave,Suite 201,Seattle, WA 98101p. 206.725.1211f. 206.973.5344www.lpdengineering.comDOWNSTREAMDRAINAGE MAPPROPERTYAPPROXIMATELY 1/4 MILEDOWNSTREAM FROM SITEAPPROXIMATE LOCATION OFLAKE WASHINGTON OUTFALLDISCHARGE POINTFROM PROPERTY12" SD SYSTEM18" SD SYSTEM24" SD SYSTEM Fire Station 15 Technical Information Report November 8, 2017; Revised January 25, 2018 APPENDIX A Design Documents NOTG STATATWFOENIHS EREDREGISLAURIEJ.PFA R RCITY OFRENTONIN COMPLIANCE WITH CITY OF RENTON STANDARDSSHEET INDEXVICINITY MAP NOTG STATATWFOENIHS EREDREGISLAURIEJ.PFA R RCITY OFRENTONIN COMPLIANCE WITH CITY OF RENTON STANDARDS NOTG STATATWFOENIHS EREDREGISLAURIEJ.PFA R RCITY OFRENTONIN COMPLIANCE WITH CITY OF RENTON STANDARDS NOTG STATATWFOENIHS EREDREGISLAURIEJ.PFA R RCITY OFRENTONIN COMPLIANCE WITH CITY OF RENTON STANDARDS 2'-4"INSIDE RIMPLAN VIEW6"AASECTION A-ASECTION B-BA514"2'-0"INSIDE2'-012"OUTSIDEB2'-4"2'-0"4'-434"5"5"4'-834"OUTSIDE RIM2'-4"INSIDE RIM2'-4"INSIDE RIMFLOWBBHFLOATABLESBAFFLEWEIR WALLCLEANOUTACCESS PLUGON WEIR WALLCONCRETE COLLARAND REBAR TO MEETHS20 IF APPLICABLE BYCONTRACTORACCESS COVERVANED INLET GRATEINLET STUB(OPTIONAL)INLET STUB(OPTIONAL)PERMANENTPOOL ELEVATIONLIFTING EYE(TYP. OF 4)CARTRIDGESUPPORTCATCHBASIN FOOT(TYP. OF 4)OUTLET STUBOUTLET PIPEFROM FLOWKITOPTIONALSLOPED LIDFINISHED GRADEFILTRATION BAYINLETPERMANENTPOOL ELEVATIONSTORMFILTERCARTRIDGEGENERAL NOTES1. CONTECH TO PROVIDE ALL MATERIALS UNLESS NOTED OTHERWISE.2. FOR SITE SPECIFIC DRAWINGS WITH DETAILED STORMFILTER CATCHBASIN STRUCTURE DIMENSIONS AND WEIGHTS, PLEASE CONTACT YOURCONTECH ENGINEERED SOLUTIONS LLC REPRESENTATIVE. www.contechES.com3. STORMFILTER CATCHBASIN WATER QUALITY STRUCTURE SHALL BE IN ACCORDANCE WITH ALL DESIGN DATA AND INFORMATION CONTAINED INTHIS DRAWING.4. INLET SHOULD NOT BE LOWER THAN OUTLET. INLET (IF APPLICABLE) AND OUTLET PIPING TO BE SPECIFIED BY ENGINEER AND PROVIDED BYCONTRACTOR.5. MANUFACTURER TO APPLY A SURFACE BEAD WELD IN THE SHAPE OF THE LETTER "O" ABOVE THE OUTLET PIPE STUB ON THE EXTERIOR SURFACEOF THE STEEL SFCB.6. STORMFILTER CATCHBASIN EQUIPPED WITH 4 INCH (APPROXIMATE) LONG STUBS FOR INLET (IF APPLICABLE) AND OUTLET PIPING. STANDARDOUTLET STUB IS 8 INCHES IN DIAMETER. MAXIMUM OUTLET STUB IS 15 INCHES IN DIAMETER. CONNECTION TO COLLECTION PIPING CAN BE MADEUSING FLEXIBLE COUPLING BY CONTRACTOR.7. STEEL STRUCTURE TO BE MANUFACTURED OF 1/4 INCH STEEL PLATE. CASTINGS SHALL MEET AASHTO M306 LOAD RATING. TO MEET HS20 LOADRATING ON STRUCTURE, A CONCRETE COLLAR IS REQUIRED. WHEN REQUIRED, CONCRETE COLLAR WITH #4 REINFORCING BARS TO BE PROVIDEDBY CONTRACTOR.8. FILTER CARTRIDGES SHALL BE MEDIA-FILLED, PASSIVE, SIPHON ACTUATED, RADIAL FLOW, AND SELF CLEANING. RADIAL MEDIA DEPTH SHALL BE7-INCHES. FILTER MEDIA CONTACT TIME SHALL BE AT LEAST 38 SECONDS.9. SPECIFIC FLOW RATE IS EQUAL TO THE FILTER TREATMENT CAPACITY (gpm) DIVIDED BY THE FILTER CONTACT SURFACE AREA (sq ft).INSTALLATION NOTESA. ANY SUB-BASE, BACKFILL DEPTH, AND/OR ANTI-FLOTATION PROVISIONS ARE SITE-SPECIFIC DESIGN CONSIDERATIONS AND SHALL BE SPECIFIED BYENGINEER OF RECORD.B. CONTRACTOR TO PROVIDE EQUIPMENT WITH SUFFICIENT LIFTING AND REACH CAPACITY TO LIFT AND SET THE CATCHBASIN (LIFTING CLUTCHESPROVIDED).C. CONTRACTOR TO TAKE APPROPRIATE MEASURES TO PROTECT CARTRIDGES FROM CONSTRUCTION-RELATED EROSION RUNOFF.FILTRATIONBAY INLETFLOW KIT1'-0"COLLARCATCHBASIN FOOT(TYP. OF 4)STORMFILTER STEEL CATCHBASIN DESIGN NOTESCARTRIDGE HEIGHTSPECIFIC FLOW RATE (gpm/sf)CARTRIDGE FLOW RATE (gpm)RECOMMENDED HYDRAULIC DROP (H)27"18" 18" DEEP3.05' 2.3' 3.3'STORMFILTER TREATMENT CAPACITY IS A FUNCTION OF THE CARTRIDGE SELECTION AND THE NUMBER OF CARTRIDGES. 1 CARTRIDGE CATCHBASINHAS A MAXIMUM OF ONE CARTRIDGE. SYSTEM IS SHOWN WITH A 27" CARTRIDGE, AND IS ALSO AVAILABLE WITH AN 18" CARTRIDGE. STORMFILTERCATCHBASIN CONFIGURATIONS ARE AVAILABLE WITH A DRY INLET BAY FOR VECTOR CONTROL.PEAK HYDRAULIC CAPACITY PER TABLE BELOW. IF THE SITE CONDITIONS EXCEED PEAK HYDRAULIC CAPACITY, AN UPSTREAM BYPASS STRUCTURE ISREQUIRED.CARTRIDGE SELECTION18.7912.5312.532 gpm/sf22.5 11.25 15 15 7.57.51.67* gpm/sf 1 gpm/sf 2 gpm/sf 1.67* gpm/sf 1 gpm/sf 2 gpm/sf 1.67* gpm/sf 1 gpm/sf* 1.67 gpm/sf SPECIFIC FLOW RATE IS APPROVED WITH PHOSPHOSORB® (PSORB) MEDIA ONLYINLET PERMANENT POOL LEVEL (A)1'-0" 1'-0" 2'-0"PEAK HYDRAULIC CAPACITY1.0 1.0 1.8OVERALL STRUCTURE HEIGHT (B)4'-9" 3'-9" 4'-9"CONFIGURATIONSTRUCTURE IDWATER QUALITY FLOW RATE (cfs)PEAK FLOW RATE (<1 cfs) RETURN PERIOD OF PEAK FLOW (yrs)CARTRIDGE FLOW RATE (gpm)MEDIA TYPE (PERLITE, ZPG, PSORB)RIM ELEVATIONPIPE DATA: I.E. DIAMETERINLET STUBOUTLET STUBNOTES/SPECIAL REQUIREMENTS:1-CARTRIDGE CATCHBASINSTORMFILTER DATASLOPED LIDSOLID COVEROUTLETINLETOUTLETINLETCARTRIDGE HEIGHT (27", 18", 18" DEEP)SD #2.014.0961007.5ZPG208.75'206.45' 6"206.45' 8"YES\NOYES\NO18"I.E. DIAMETERSD #10.004.0291007.5ZPG210.30'209.30' 6"208.00' 8"18"YES\NOYES\NONOTG STATATWFOENIHS EREDREGISLAURIEJ.PFA R RCITY OFRENTONIN COMPLIANCE WITH CITY OF RENTON STANDARDS NOTG STATATWFOENIHS EREDREGISLAURIEJ.PFA R RCITY OFRENTONIN COMPLIANCE WITH CITY OF RENTON STANDARDS NOTG STATATWFOENIHS EREDREGISLAURIEJ.PFA R RCITY OFRENTONIN COMPLIANCE WITH CITY OF RENTON STANDARDS NOTG STATATWFOENIHS EREDREGISLAURIEJ.PFA R RCITY OFRENTONIN COMPLIANCE WITH CITY OF RENTON STANDARDS NOTG STATATWFOENIHS EREDREGISLAURIEJ.PFA R RCITY OFRENTONIN COMPLIANCE WITH CITY OF RENTON STANDARDS NOTG STATATWFOENIHS EREDREGISLAURIEJ.PFA R RCITY OFRENTONIN COMPLIANCE WITH CITY OF RENTON STANDARDS NOTG STATATWFOENIHS EREDREGISLAURIEJ.PFA R RCITY OFRENTONIN COMPLIANCE WITH CITY OF RENTON STANDARDS NOTG STATATWFOENIHS EREDREGISLAURIEJ.PFA R RCITY OFRENTONIN COMPLIANCE WITH CITY OF RENTON STANDARDS NOTG STATATWFOENIHS EREDREGISLAURIEJ.PFA R RCITY OFRENTONIN COMPLIANCE WITH CITY OF RENTON STANDARDS Fire Station 15 Technical Information Report November 8, 2017; Revised January 25, 2018 APPENDIX B Design Calculations On‐Site to Bio Pond (SF) (AC) Roof 5,485 0.1259 NPGIS 305 0.0070 Drive Apron 1,145 0.0263 Bioretention Pond 300 0.0070 Total Impervious to Bio 6,935 0.1592 Total Pervious (Bio) 300 0.0069 Impervious Area (Pervious Pavement)4,170 0.0957 On‐Site Direct to Vault (SF) (AC) PGIS 5,585 0.1282 NPGIS 845 0.0194 Roof 2,270 0.0521 Landscape 7,545 0.1732 Total Impervious On‐Site to Vault 8,700 0.1997 Total Pervious On‐Site to Vault 7,545 0.1732 On‐Site Bypass Area (SF) (AC) PGIS 1,020 0.0234 Walk 1,150 0.0264 Landscape 1,190 0.0273 Total Impervious On‐Site 2,170 0.0498 Total Pervious On‐Site 1,190 0.0273 ROW Bypass Area (SF) (AC) PGIS 980 0.0225 Walk 55 0.0013 Landscape ‐ 0.0000 Total Impervious ROW 1,035 0.0238 Total Pervious ROW ‐ 0.0000 Total Impervious 23,010 0.5282 Total Pervious 9,035 0.2074 Total Disturbed 32,045 0.7357 Percentage of Target Impervious 72% 20% of Target Surface 4,602 Proposed Areas ————————————————————————————————— MGS FLOOD PROJECT REPORT – FC & WQ ANALYSIS Program Version: MGSFlood 4.46 Program License Number: 201410003 Project Simulation Performed on: 01/25/2018 11:28 AM Report Generation Date: 01/25/2018 11:30 AM ————————————————————————————————— Input File Name: Detention_WQ_Design2.fld Project Name: FS 15 Analysis Title: Detention Comments: Total Impervious = 23,010 SF ———————————————— PRECIPITATION INPUT ———————————————— Computational Time Step (Minutes): 15 Extended Precipitation Time Series Selected Climatic Region Number: 15 Full Period of Record Available used for Routing Precipitation Station : 96004005 Puget East 40 in_5min 10/01/1939-10/01/2097 Evaporation Station : 961040 Puget East 40 in MAP Evaporation Scale Factor : 0.750 HSPF Parameter Region Number: 1 HSPF Parameter Region Name : USGS Default ********** Default HSPF Parameters Used (Not Modified by User) *************** ********************** WATERSHED DEFINITION *********************** Predevelopment/Post Development Tributary Area Summary Predeveloped Post Developed Total Subbasin Area (acres) 0.735 0.632 Area of Links that Include Precip/Evap (acres) 0.000 0.103 Total (acres) 0.735 0.735 ----------------------SCENARIO: PREDEVELOPED Number of Subbasins: 1 ---------- Subbasin : Pre-dev Basin ---------- -------Area (Acres) -------- Till Grass 0.735 ---------------------------------------------- Subbasin Total 0.735 ----------------------SCENARIO: POSTDEVELOPED Number of Subbasins: 5 ---------- Subbasin : Direct to Det ---------- -------Area (Acres) -------- Till Grass 0.077 Impervious 0.200 ---------------------------------------------- Subbasin Total 0.277 ---------- Subbasin : On-site Bypass ---------- -------Area (Acres) -------- Till Grass 0.027 Impervious 0.050 ---------------------------------------------- Subbasin Total 0.077 Within MGSFlood the "Area of Links that include Precip/Evap" is the Bioretention Element (0.007 acre) and the Pervious Pavement Element (0.096 acre) which totals 0.103 acre. These areas are subtracted from the post- developed basin elements. The area listed as Grass Till is 0.173 acre minus the Pervious Pavement Element 0.096 acre which totals 0.077 acre ---------- Subbasin : Sub to Bio ---------- -------Area (Acres) -------- Impervious 0.159 ---------------------------------------------- Subbasin Total 0.159 ---------- Subbasin : Por Pavmt ---------- -------Area (Acres) -------- Impervious 0.096 ---------------------------------------------- Subbasin Total 0.096 ---------- Subbasin : ROW Bypass ---------- -------Area (Acres) -------- Impervious 0.023 ---------------------------------------------- Subbasin Total 0.023 ************************* LINK DATA ******************************* ----------------------SCENARIO: PREDEVELOPED Number of Links: 1 ------------------------------------------ Link Name: New Copy Lnk1 Link Type: Copy Downstream Link: None ************************* LINK DATA ******************************* ----------------------SCENARIO: POSTDEVELOPED Number of Links: 5 ------------------------------------------ Link Name: Pnt of Discharge Link Type: Copy Downstream Link: None ------------------------------------------ Link Name: Bio Pond Link Type: Bioretention Facility Downstream Link Name: Gravel Basin Base Elevation (ft) : 100.00 Riser Crest Elevation (ft) : 100.50 Storage Depth (ft) : 0.50 Bottom Length (ft) : 100.0 Bottom Width (ft) : 3.0 The pervious area is 0.007 acre is included in the Bioretention Pond Element (3*100=300SF=0.007 acre) Side Slopes (ft/ft) : L1= 3.00 L2= 3.00 W1= 3.00 W2= 3.00 Bottom Area (sq-ft) : 300. Area at Riser Crest El (sq-ft) : 618. (acres) : 0.014 Volume at Riser Crest (cu-ft) : 409. (ac-ft) : 0.009 Infiltration on Bottom and Sideslopes Selected Soil Properties Biosoil Thickness (ft) : 1.50 Biosoil Saturated Hydraulic Conductivity (in/hr) : 1.00 Biosoil Porosity (Percent) : 40.00 Maximum Elevation of Bioretention Soil : 102.00 Native Soil Hydraulic Conductivity (in/hr) : 0.00 Riser Geometry Riser Structure Type : Circular Riser Diameter (in) : 8.00 Common Length (ft) : 0.000 Riser Crest Elevation : 100.50 ft Hydraulic Structure Geometry Number of Devices: 0 ------------------------------------------ Link Name: WQ Por Pavemt Link Type: Porous Pavement Structure Downstream Link Name: StormTech Pavement Length (ft) : 100.00 Pavement Width (ft) : 41.70 Pavement Slope (ft/ft) : 0.017 Pavement Infiltration Rate (in/hr) : 20.000 Number of Infiltration Cells : 2 Trench Cell Length (ft) : 100.00 Trench Cell Width (ft) : 41.80 Trench Cell Depth (ft) : 3.00 Trench Gravel Porosity (%) : 30.00 Trench Bed Slope (ft/ft) : 0.005 Native Soil Infiltration Rate (in/hr) : 1.100 ------------------------------------------ Link Name: Gravel Basin Link Type: Infiltration Trench Downstream Link Name: StormTech Trench Type : Trench on Embankment Sideslope Trench Length (ft) : 28.00 Trench Width (ft) : 3.00 Trench Depth (ft) : 5.00 Trench Bottom Elev (ft) : 95.00 NOTE: VALUES FROM RSWDMA SECTION 6.8.1.5 Trench Rockfill Porosity (%) : 30.00 Constant Infiltration Option Used Infiltration Rate (in/hr): 1.10 ------------------------------------------ Link Name: StormTech Link Type: Structure Downstream Link Name: Pnt of Discharge User Specified Elevation Volume Table Used Elevation (ft) Pond Volume (cu-ft) 100.00 0. 100.08 12. 100.17 24. 100.25 35. 100.33 47. 100.42 59. 100.50 71. 100.58 92. 100.67 113. 100.75 135. 100.83 156. 100.92 177. 101.00 198. 101.08 219. 101.17 240. 101.25 260. 101.33 281. 101.42 301. 101.50 321. 101.58 341. 101.67 361. 101.75 380. 101.83 399. 101.92 418. 102.00 437. 102.08 455. 102.17 474. 102.25 491. 102.33 509. 102.42 526. 102.50 542. 102.58 558. 102.67 573. 102.75 588. 102.83 601. 102.92 613. 103.00 625. 103.08 637. 103.17 649. 103.25 660. 103.33 672. 103.42 684. 103.50 696. Massmann Infiltration Option Used Hydraulic Conductivity (in/hr) : 0.00 Depth to Water Table (ft) : 100.00 Bio-Fouling Potential : Low Maintenance : Average or Better Riser Geometry Riser Structure Type : Circular Riser Diameter (in) : 18.00 Common Length (ft) : 0.000 Riser Crest Elevation : 103.00 ft Hydraulic Structure Geometry Number of Devices: 1 ---Device Number 1 --- Device Type : Circular Orifice Control Elevation (ft) : 100.00 Diameter (in) : 1.00 Orientation : Horizontal Elbow : Yes **********************FLOOD FREQUENCY AND DURATION STATISTICS******************* ----------------------SCENARIO: PREDEVELOPED Number of Subbasins: 1 Number of Links: 1 ----------------------SCENARIO: POSTDEVELOPED Number of Subbasins: 5 Number of Links: 5 ***********Groundwater Recharge Summary ************* Recharge is computed as input to Perlnd Groundwater Plus Infiltration in Structures Total Predeveloped Recharge During Simulation Model Element Recharge Amount (ac-ft) ----------------------------------------------------------------------------------------------- Subbasin: Pre-dev Basin 89.825 Link: New Copy Lnk1 0.000 _____________________________________ Total: 89.825 Total Post Developed Recharge During Simulation Model Element Recharge Amount (ac-ft) ----------------------------------------------------------------------------------------------- Subbasin: Direct to Det 9.410 Subbasin: On-site Bypass 3.300 Subbasin: Sub to Bio 0.000 Subbasin: Por Pavmt 0.000 Subbasin: ROW Bypass 0.000 Link: Pnt of Discharge 0.000 Link: Bio Pond Not Computed Link: WQ Por Pavemt Not Computed Link: Gravel Basin 68.379 Link: StormTech Not Computed _____________________________________ Total: 81.089 Total Predevelopment Recharge is Greater than Post Developed Average Recharge Per Year, (Number of Years= 158) Predeveloped: 0.569 ac-ft/year, Post Developed: 0.513 ac-ft/year ***********Water Quality Facility Data ************* ----------------------SCENARIO: PREDEVELOPED Number of Links: 1 ********** Link: New Copy Lnk1 ********** Infiltration/Filtration Statistics-------------------- Inflow Volume (ac-ft): 147.81 Inflow Volume Including PPT-Evap (ac-ft): 147.81 Total Runoff Infiltrated (ac-ft): 0.00, 0.00% Total Runoff Filtered (ac-ft): 0.00, 0.00% Primary Outflow To Downstream System (ac-ft): 147.81 Secondary Outflow To Downstream System (ac-ft): 0.00 Percent Treated (Infiltrated+Filtered)/Total Volume: 0.00% ----------------------SCENARIO: POSTDEVELOPED Number of Links: 5 ********** Link: Pnt of Discharge ********** Infiltration/Filtration Statistics-------------------- Inflow Volume (ac-ft): 150.31 Inflow Volume Including PPT-Evap (ac-ft): 150.31 Total Runoff Infiltrated (ac-ft): 0.00, 0.00% Total Runoff Filtered (ac-ft): 0.00, 0.00% Primary Outflow To Downstream System (ac-ft): 150.31 Secondary Outflow To Downstream System (ac-ft): 0.00 Percent Treated (Infiltrated+Filtered)/Total Volume: 0.00% ********** Link: Gravel Basin ********** Infiltration/Filtration Statistics-------------------- Inflow Volume (ac-ft): 74.92 Inflow Volume Including PPT-Evap (ac-ft): 74.92 Total Runoff Infiltrated (ac-ft): 68.38, 91.27% Total Runoff Filtered (ac-ft): 0.00, 0.00% Primary Outflow To Downstream System (ac-ft): 6.59 Secondary Outflow To Downstream System (ac-ft): 0.00 Percent Treated (Infiltrated+Filtered)/Total Volume: 91.27% ***********Compliance Point Results ************* Scenario Predeveloped Compliance Link: New Copy Lnk1 Scenario Postdeveloped Compliance Link: Pnt of Discharge *** Point of Compliance Flow Frequency Data *** Recurrence Interval Computed Using Gringorten Plotting Position Predevelopment Runoff Postdevelopment Runoff Tr (Years) Discharge (cfs) Tr (Years) Discharge (cfs) ---------------------------------------------------------------------------------------------------------------------- 2-Year 6.915E-02 2-Year 5.771E-02 5-Year 0.119 5-Year 0.134 10-Year 0.174 10-Year 0.162 25-Year 0.263 25-Year 0.230 50-Year 0.341 50-Year 0.247 100-Year 0.375 100-Year 0.336 200-Year 0.412 200-Year 0.373 ** Record too Short to Compute Peak Discharge for These Recurrence Intervals ————————————————————————————————— MGS FLOOD PROJECT REPORT – BYPASS TARGET SURFACES Program Version: MGSFlood 4.46 Program License Number: 201410003 Project Simulation Performed on: 01/25/2018 1:04 PM Report Generation Date: 01/25/2018 1:05 PM ————————————————————————————————— Input File Name: Bypass Target Surfaces.fld Project Name: FS 15 Analysis Title: Detention Comments: Total Impervious = 23,010 SF ———————————————— PRECIPITATION INPUT ———————————————— Computational Time Step (Minutes): 15 Extended Precipitation Time Series Selected Climatic Region Number: 15 Full Period of Record Available used for Routing Precipitation Station : 96004005 Puget East 40 in_5min 10/01/1939-10/01/2097 Evaporation Station : 961040 Puget East 40 in MAP Evaporation Scale Factor : 0.750 HSPF Parameter Region Number: 1 HSPF Parameter Region Name : USGS Default ********** Default HSPF Parameters Used (Not Modified by User) *************** ********************** WATERSHED DEFINITION *********************** Predevelopment/Post Development Tributary Area Summary Predeveloped Post Developed Total Subbasin Area (acres) 0.100 0.100 Area of Links that Include Precip/Evap (acres) 0.000 0.000 Total (acres) 0.100 0.100 ----------------------SCENARIO: PREDEVELOPED Number of Subbasins: 1 ---------- Subbasin : Pre-dev Basin ---------- -------Area (Acres) -------- Till Grass 0.100 ---------------------------------------------- Subbasin Total 0.100 ----------------------SCENARIO: POSTDEVELOPED Number of Subbasins: 2 ---------- Subbasin : On-site Bypass ---------- -------Area (Acres) -------- Till Grass 0.027 Impervious 0.050 ---------------------------------------------- Subbasin Total 0.077 ---------- Subbasin : ROW Bypass ---------- -------Area (Acres) -------- Impervious 0.023 ---------------------------------------------- Subbasin Total 0.023 ************************* LINK DATA ******************************* ----------------------SCENARIO: PREDEVELOPED Number of Links: 1 ------------------------------------------ Link Name: New Copy Lnk1 Link Type: Copy Downstream Link: None ************************* LINK DATA ******************************* ----------------------SCENARIO: POSTDEVELOPED Number of Links: 1 ------------------------------------------ Link Name: Pnt of Discharge Link Type: Copy Downstream Link: None **********************FLOOD FREQUENCY AND DURATION STATISTICS******************* ----------------------SCENARIO: PREDEVELOPED Number of Subbasins: 1 Number of Links: 1 ----------------------SCENARIO: POSTDEVELOPED Number of Subbasins: 2 Number of Links: 1 ***********Groundwater Recharge Summary ************* Recharge is computed as input to Perlnd Groundwater Plus Infiltration in Structures Total Predeveloped Recharge During Simulation Model Element Recharge Amount (ac-ft) ----------------------------------------------------------------------------------------------- Subbasin: Pre-dev Basin 12.221 Link: New Copy Lnk1 0.000 _____________________________________ Total: 12.221 Total Post Developed Recharge During Simulation Model Element Recharge Amount (ac-ft) ----------------------------------------------------------------------------------------------- Subbasin: On-site Bypass 3.300 Subbasin: ROW Bypass 0.000 Link: Pnt of Discharge 0.000 _____________________________________ Total: 3.300 Total Predevelopment Recharge is Greater than Post Developed Average Recharge Per Year, (Number of Years= 158) Predeveloped: 0.077 ac-ft/year, Post Developed: 0.021 ac-ft/year ***********Water Quality Facility Data ************* ----------------------SCENARIO: PREDEVELOPED Number of Links: 1 ********** Link: New Copy Lnk1 ********** Infiltration/Filtration Statistics-------------------- Inflow Volume (ac-ft): 20.11 Inflow Volume Including PPT-Evap (ac-ft): 20.11 Total Runoff Infiltrated (ac-ft): 0.00, 0.00% Total Runoff Filtered (ac-ft): 0.00, 0.00% Primary Outflow To Downstream System (ac-ft): 20.11 Secondary Outflow To Downstream System (ac-ft): 0.00 Percent Treated (Infiltrated+Filtered)/Total Volume: 0.00% ----------------------SCENARIO: POSTDEVELOPED Number of Links: 1 ********** Link: Pnt of Discharge ********** Infiltration/Filtration Statistics-------------------- Inflow Volume (ac-ft): 38.16 Inflow Volume Including PPT-Evap (ac-ft): 38.16 Total Runoff Infiltrated (ac-ft): 0.00, 0.00% Total Runoff Filtered (ac-ft): 0.00, 0.00% Primary Outflow To Downstream System (ac-ft): 38.16 Secondary Outflow To Downstream System (ac-ft): 0.00 Percent Treated (Infiltrated+Filtered)/Total Volume: 0.00% ***********Compliance Point Results ************* Scenario Predeveloped Compliance Link: New Copy Lnk1 Scenario Postdeveloped Compliance Link: Pnt of Discharge *** Point of Compliance Flow Frequency Data *** Recurrence Interval Computed Using Gringorten Plotting Position Predevelopment Runoff Postdevelopment Runoff Tr (Years) Discharge (cfs) Tr (Years) Discharge (cfs) ---------------------------------------------------------------------------------------------------------------------- 2-Year 9.408E-03 2-Year 2.949E-02 5-Year 1.613E-02 5-Year 3.771E-02 10-Year 2.362E-02 10-Year 4.581E-02 25-Year 3.584E-02 25-Year 6.173E-02 50-Year 4.640E-02 50-Year 7.143E-02 100-Year 5.096E-02 100-Year 8.932E-02 200-Year 5.603E-02 200-Year 9.048E-02 ** Record too Short to Compute Peak Discharge for These Recurrence Intervals DELTA = 0.038 CFS Fire Station 15 Stage‐Storage Table Spreadsheet for Detention Facility Bottom Width of Gravel Basin 11.00 ft Bottom Length of Gravel Basin 32.08 ft Gravel Depth Beneath Chambers 6 inches Gravel Above Chambers 6 inches Void Space of Gravel 40% Number of rows of Chambers 2 rows Chamber Length 7.12 feet Total Length of Chambers 28.47 feet Total number of Chambers per Row 4 Chambers per row Total Storage Volume in System 625 cubic feet Infiltration Rate = 0 in/hr Stage Storage Table:Tables for MGSFlood Stage Height (inches) Stage Height (ft)Single Chamber Volume (CF) Cross sectional area of Chambers (SF per LF) Total Volume in Chambers (CF) Cross section of gravel area (SF per LF) Volume in Gravel (CF)Total Cumulative Storage (CF)Surface Area (ac) Storage (ac‐ft)Infil. Through Btm of Facility (cfs)stage area storage 0 0.000 0.00 0.00 0 0.00 0 0 0.000000 0.000000 0.000000 100.000 0 0 1 0.083 0.00 0.00 0 0.92 12 12 0.008101 0.000270 0.000000 100.083 352.88 12 2 0.167 0.00 0.00 0 1.83 24 24 0.008101 0.000540 0.000000 100.167 352.98 24 3 0.250 0.00 0.00 0 2.75 35 35 0.008101 0.000810 0.000000 100.250 353.08 35 4 0.333 0.00 0.00 0 3.67 47 47 0.008101 0.001080 0.000000 100.333 353.18 47 5 0.417 0.00 0.00 0 4.58 59 59 0.008101 0.001350 0.000000 100.417 353.28 59 6 0.500 0.00 0.00 0 5.50 71 71 0.008101 0.001620 0.000000 100.500 353.38 71 7 0.583 2.21 0.62 18 5.80 74 92 0.008101 0.002113 0.000000 100.583 353.48 92 8 0.667 4.41 1.24 35 6.09 78 113 0.008101 0.002605 0.000000 100.667 353.58 113 9 0.750 6.58 1.85 53 6.40 82 135 0.008101 0.003094 0.000000 100.750 353.68 135 10 0.833 8.74 2.46 70 6.71 86 156 0.008101 0.003582 0.000000 100.833 353.78 156 11 0.917 10.87 3.05 87 7.03 90 177 0.008101 0.004067 0.000000 100.917 353.88 177 12 1.000 12.97 3.64 104 7.36 94 198 0.008101 0.004549 0.000000 101.000 353.98 198 13 1.083 15.04 4.23 120 7.69 99 219 0.008101 0.005027 0.000000 101.083 354.08 219 14 1.167 17.08 4.80 137 8.03 103 240 0.008101 0.005503 0.000000 101.167 354.18 240 15 1.250 19.09 5.36 153 8.39 108 260 0.008101 0.005976 0.000000 101.250 354.28 260 16 1.333 21.06 5.92 168 8.75 112 281 0.008101 0.006445 0.000000 101.333 354.38 281 17 1.417 23.00 6.46 184 9.12 117 301 0.008101 0.006911 0.000000 101.417 354.48 301 18 1.500 24.89 6.99 199 9.51 122 321 0.008101 0.007371 0.000000 101.500 354.58 321 19 1.583 26.74 7.51 214 9.90 127 341 0.008101 0.007828 0.000000 101.583 354.68 341 20 1.667 28.54 8.02 228 10.31 132 361 0.008101 0.008279 0.000000 101.667 354.78 361 21 1.750 30.29 8.51 242 10.74 138 380 0.008101 0.008726 0.000000 101.750 354.88 380 22 1.833 31.99 8.99 256 11.18 143 399 0.008101 0.009168 0.000000 101.833 354.98 399 23 1.917 33.64 9.45 269 11.63 149 418 0.008101 0.009604 0.000000 101.917 355.08 418 24 2.000 35.22 9.90 282 12.10 155 437 0.008101 0.010033 0.000000 102.000 355.18 437 25 2.083 36.74 10.33 294 12.59 162 455 0.008101 0.010457 0.000000 102.083 355.28 455 26 2.167 38.18 10.73 305 13.10 168 474 0.008101 0.010872 0.000000 102.167 355.38 474 27 2.250 39.54 11.11 316 13.64 175 491 0.008101 0.011279 0.000000 102.250 355.48 491 28 2.333 40.80 11.47 326 14.20 182 509 0.008101 0.011676 0.000000 102.333 355.58 509 29 2.417 41.98 11.80 336 14.79 190 526 0.008101 0.012065 0.000000 102.417 355.68 526 30 2.500 43.06 12.10 344 15.40 198 542 0.008101 0.012444 0.000000 102.500 355.78 542 31 2.583 44.01 12.37 352 16.05 206 558 0.008101 0.012810 0.000000 102.583 355.88 558 32 2.667 44.81 12.59 358 16.74 215 573 0.008101 0.013161 0.000000 102.667 355.98 573 33 2.750 45.41 12.76 363 17.49 224 588 0.008101 0.013492 0.000000 102.750 356.08 588 34 2.833 45.69 12.84 366 18.33 235 601 0.008101 0.013790 0.000000 102.833 356.18 601 35 2.917 45.85 12.89 367 19.20 246 613 0.008101 0.014076 0.000000 102.917 356.28 613 36 3.000 45.90 12.90 367 20.10 258 625 0.008101 0.014351 0.000000 103.000 356.38 625 37 3.083 45.90 12.90 367 21.02 270 637 0.008101 0.014621 0.000000 103.083 356.48 637 38 3.167 45.90 12.90 367 21.93 281 649 0.008101 0.014891 0.000000 103.167 356.58 649 39 3.250 45.90 12.90 367 22.85 293 660 0.008101 0.015161 0.000000 103.250 356.68 660 40 3.333 45.90 12.90 367 23.77 305 672 0.008101 0.015431 0.000000 103.333 356.78 672 41 3.417 45.90 12.90 367 24.68 317 684 0.008101 0.015701 0.000000 103.417 356.88 684 42 3.500 45.90 12.90 367 25.60 329 696 0.008101 0.015971 0.000000 103.500 356.98 696 43 3.583 45.90 12.90 367 26.52 340 707 0.008101 0.016241 0.000000 103.583 357.08 707 44 3.667 45.90 12.90 367 27.43 352 719 0.008101 0.016511 0.000000 103.667 357.18 719 45 3.750 45.90 12.90 367 28.35 364 731 0.008101 0.016781 0.000000 103.750 357.28 731 46 3.833 45.90 12.90 367 29.27 376 743 0.008101 0.017051 0.000000 103.833 357.38 743 47 3.917 45.90 12.90 367 30.18 387 755 0.008101 0.017321 0.000000 103.917 357.48 755 48 4.000 45.90 12.90 367 31.10 399 766 0.008101 0.017591 0.000000 104.000 357.58 766 ————————————————————————————————— MGS FLOOD PROJECT REPORT – WQ STORMFILTER (EAST BASIN) Program Version: MGSFlood 4.46 Program License Number: 201410003 Project Simulation Performed on: 01/12/2018 10:35 AM Report Generation Date: 02/07/2018 4:19 PM ————————————————————————————————— Input File Name: FS 15 WQ Flow Rates.fld Project Name: FS 15 Analysis Title: WQ Comments: ———————————————— PRECIPITATION INPUT ———————————————— Computational Time Step (Minutes): 15 Extended Precipitation Time Series Selected Climatic Region Number: 15 Full Period of Record Available used for Routing Precipitation Station : 96004005 Puget East 40 in_5min 10/01/1939-10/01/2097 Evaporation Station : 961040 Puget East 40 in MAP Evaporation Scale Factor : 0.750 HSPF Parameter Region Number: 1 HSPF Parameter Region Name : USGS Default ********** Default HSPF Parameters Used (Not Modified by User) *************** ********************** WATERSHED DEFINITION *********************** Predevelopment/Post Development Tributary Area Summary Predeveloped Post Developed Total Subbasin Area (acres) 0.029 0.029 Area of Links that Include Precip/Evap (acres) 0.000 0.000 Total (acres) 0.029 0.029 ----------------------SCENARIO: PREDEVELOPED Number of Subbasins: 1 ---------- Subbasin : Pre-dev Basin ---------- -------Area (Acres) -------- Till Grass 0.029 ---------------------------------------------- Subbasin Total 0.029 ----------------------SCENARIO: POSTDEVELOPED Number of Subbasins: 1 ---------- Subbasin : Subbasin 1 ---------- -------Area (Acres) -------- Impervious 0.029 ---------------------------------------------- Subbasin Total 0.029 ************************* LINK DATA ******************************* ----------------------SCENARIO: PREDEVELOPED Number of Links: 1 ------------------------------------------ Link Name: New Copy Lnk1 Link Type: Copy Downstream Link: None ************************* LINK DATA ******************************* ----------------------SCENARIO: POSTDEVELOPED Number of Links: 1 ------------------------------------------ Link Name: New Copy Lnk1 Link Type: Copy Downstream Link: None **********************FLOOD FREQUENCY AND DURATION STATISTICS******************* ----------------------SCENARIO: PREDEVELOPED Number of Subbasins: 1 Number of Links: 1 ----------------------SCENARIO: POSTDEVELOPED Number of Subbasins: 1 Number of Links: 1 ***********Groundwater Recharge Summary ************* Recharge is computed as input to Perlnd Groundwater Plus Infiltration in Structures Total Predeveloped Recharge During Simulation Model Element Recharge Amount (ac-ft) ----------------------------------------------------------------------------------------------- Subbasin: Pre-dev Basin 3.544 Link: New Copy Lnk1 0.000 _____________________________________ Total: 3.544 Total Post Developed Recharge During Simulation Model Element Recharge Amount (ac-ft) ----------------------------------------------------------------------------------------------- Subbasin: Subbasin 1 0.000 Link: New Copy Lnk1 0.000 _____________________________________ Total: 0.000 Total Predevelopment Recharge is Greater than Post Developed Average Recharge Per Year, (Number of Years= 158) Predeveloped: 0.022 ac-ft/year, Post Developed: 0.000 ac-ft/year ***********Water Quality Facility Data ************* ----------------------SCENARIO: PREDEVELOPED Number of Links: 1 ********** Link: New Copy Lnk1 ********** Infiltration/Filtration Statistics-------------------- Inflow Volume (ac-ft): 5.83 Inflow Volume Including PPT-Evap (ac-ft): 5.83 Total Runoff Infiltrated (ac-ft): 0.00, 0.00% Total Runoff Filtered (ac-ft): 0.00, 0.00% Primary Outflow To Downstream System (ac-ft): 5.83 Secondary Outflow To Downstream System (ac-ft): 0.00 Percent Treated (Infiltrated+Filtered)/Total Volume: 0.00% ----------------------SCENARIO: POSTDEVELOPED Number of Links: 1 ********** Link: New Copy Lnk1 ********** 15-Minute Timestep, Water Quality Treatment Design Discharge On-line Design Discharge Rate (91% Exceedance): 0.00 cfs Off-line Design Discharge Rate (91% Exceedance): 0.00 cfs Infiltration/Filtration Statistics-------------------- Inflow Volume (ac-ft): 13.00 Inflow Volume Including PPT-Evap (ac-ft): 13.00 Total Runoff Infiltrated (ac-ft): 0.00, 0.00% Total Runoff Filtered (ac-ft): 0.00, 0.00% Primary Outflow To Downstream System (ac-ft): 13.00 Secondary Outflow To Downstream System (ac-ft): 0.00 Percent Treated (Infiltrated+Filtered)/Total Volume: 0.00% ***********Compliance Point Results ************* Scenario Predeveloped Compliance Link: New Copy Lnk1 Scenario Postdeveloped Compliance Link: New Copy Lnk1 *** Point of Compliance Flow Frequency Data *** Recurrence Interval Computed Using Gringorten Plotting Position Predevelopment Runoff Postdevelopment Runoff Tr (Years) Discharge (cfs) Tr (Years) Discharge (cfs) ---------------------------------------------------------------------------------------------------------------------- 2-Year 2.728E-03 2-Year 1.081E-02 5-Year 4.679E-03 5-Year 1.404E-02 10-Year 6.851E-03 10-Year 1.579E-02 25-Year 1.039E-02 25-Year 1.988E-02 50-Year 1.346E-02 50-Year 2.530E-02 100-Year 1.478E-02 100-Year 2.926E-02 200-Year 1.625E-02 200-Year 3.032E-02 ** Record too Short to Compute Peak Discharge for These Recurrence Intervals ————————————————————————————————— MGS FLOOD PROJECT REPORT– WQ STORMFILTER (WEST BASIN) Program Version: MGSFlood 4.46 Program License Number: 201410003 Project Simulation Performed on: 01/12/2018 10:41 AM Report Generation Date: 02/07/2018 4:20 PM ————————————————————————————————— Input File Name: FS 15 WQ Flow Rates.fld Project Name: FS 15 Analysis Title: WQ Comments: ———————————————— PRECIPITATION INPUT ———————————————— Computational Time Step (Minutes): 15 Extended Precipitation Time Series Selected Climatic Region Number: 15 Full Period of Record Available used for Routing Precipitation Station : 96004005 Puget East 40 in_5min 10/01/1939-10/01/2097 Evaporation Station : 961040 Puget East 40 in MAP Evaporation Scale Factor : 0.750 HSPF Parameter Region Number: 1 HSPF Parameter Region Name : USGS Default ********** Default HSPF Parameters Used (Not Modified by User) *************** ********************** WATERSHED DEFINITION *********************** Predevelopment/Post Development Tributary Area Summary Predeveloped Post Developed Total Subbasin Area (acres) 0.095 0.095 Area of Links that Include Precip/Evap (acres) 0.000 0.000 Total (acres) 0.095 0.095 ----------------------SCENARIO: PREDEVELOPED Number of Subbasins: 1 ---------- Subbasin : Pre-dev Basin ---------- -------Area (Acres) -------- Till Grass 0.095 ---------------------------------------------- Subbasin Total 0.095 ----------------------SCENARIO: POSTDEVELOPED Number of Subbasins: 1 ---------- Subbasin : Subbasin 1 ---------- -------Area (Acres) -------- Impervious 0.095 ---------------------------------------------- Subbasin Total 0.095 ************************* LINK DATA ******************************* ----------------------SCENARIO: PREDEVELOPED Number of Links: 1 ------------------------------------------ Link Name: New Copy Lnk1 Link Type: Copy Downstream Link: None ************************* LINK DATA ******************************* ----------------------SCENARIO: POSTDEVELOPED Number of Links: 1 ------------------------------------------ Link Name: New Copy Lnk1 Link Type: Copy Downstream Link: None **********************FLOOD FREQUENCY AND DURATION STATISTICS******************* ----------------------SCENARIO: PREDEVELOPED Number of Subbasins: 1 Number of Links: 1 ----------------------SCENARIO: POSTDEVELOPED Number of Subbasins: 1 Number of Links: 1 ***********Groundwater Recharge Summary ************* Recharge is computed as input to Perlnd Groundwater Plus Infiltration in Structures Total Predeveloped Recharge During Simulation Model Element Recharge Amount (ac-ft) ----------------------------------------------------------------------------------------------- Subbasin: Pre-dev Basin 11.610 Link: New Copy Lnk1 0.000 _____________________________________ Total: 11.610 Total Post Developed Recharge During Simulation Model Element Recharge Amount (ac-ft) ----------------------------------------------------------------------------------------------- Subbasin: Subbasin 1 0.000 Link: New Copy Lnk1 0.000 _____________________________________ Total: 0.000 Total Predevelopment Recharge is Greater than Post Developed Average Recharge Per Year, (Number of Years= 158) Predeveloped: 0.073 ac-ft/year, Post Developed: 0.000 ac-ft/year ***********Water Quality Facility Data ************* ----------------------SCENARIO: PREDEVELOPED Number of Links: 1 ********** Link: New Copy Lnk1 ********** Infiltration/Filtration Statistics-------------------- Inflow Volume (ac-ft): 19.10 Inflow Volume Including PPT-Evap (ac-ft): 19.10 Total Runoff Infiltrated (ac-ft): 0.00, 0.00% Total Runoff Filtered (ac-ft): 0.00, 0.00% Primary Outflow To Downstream System (ac-ft): 19.10 Secondary Outflow To Downstream System (ac-ft): 0.00 Percent Treated (Infiltrated+Filtered)/Total Volume: 0.00% ----------------------SCENARIO: POSTDEVELOPED Number of Links: 1 ********** Link: New Copy Lnk1 ********** 15-Minute Timestep, Water Quality Treatment Design Discharge On-line Design Discharge Rate (91% Exceedance): 0.01 cfs Off-line Design Discharge Rate (91% Exceedance): 0.01 cfs Infiltration/Filtration Statistics-------------------- Inflow Volume (ac-ft): 42.59 Inflow Volume Including PPT-Evap (ac-ft): 42.59 Total Runoff Infiltrated (ac-ft): 0.00, 0.00% Total Runoff Filtered (ac-ft): 0.00, 0.00% Primary Outflow To Downstream System (ac-ft): 42.59 Secondary Outflow To Downstream System (ac-ft): 0.00 Percent Treated (Infiltrated+Filtered)/Total Volume: 0.00% ***********Compliance Point Results ************* Scenario Predeveloped Compliance Link: New Copy Lnk1 Scenario Postdeveloped Compliance Link: New Copy Lnk1 *** Point of Compliance Flow Frequency Data *** Recurrence Interval Computed Using Gringorten Plotting Position Predevelopment Runoff Postdevelopment Runoff Tr (Years) Discharge (cfs) Tr (Years) Discharge (cfs) ---------------------------------------------------------------------------------------------------------------------- 2-Year 8.938E-03 2-Year 3.540E-02 5-Year 1.533E-02 5-Year 4.599E-02 10-Year 2.244E-02 10-Year 5.173E-02 25-Year 3.405E-02 25-Year 6.512E-02 50-Year 4.408E-02 50-Year 8.289E-02 100-Year 4.841E-02 100-Year 9.584E-02 200-Year 5.323E-02 200-Year 9.934E-02 ** Record too Short to Compute Peak Discharge for These Recurrence Intervals Size and Cost Estimate 11835 NE Glenn Widing Dr., Portland OR 97220 Toll-free: 800.548.4667 Fax: 800.561.1271 ©2012 Contech Engineered Solutions LLC www.conteches.com Page 1 of 1 TS-P027 Prepared by Mike Gillette on January 12, 2018 Fire Station 15 – Stormwater Treatment System Renton, WA Information provided: • Presiding agency = City of Renton Structure ID West Basin East Basin Water Quality Flow Rate (cfs) 0.014 0.004 Peak Flow Rate (cfs) 0.096 0.029 Number of cartridges 1 1 Cartridge flow rate (gpm) 7.5 7.5 Media type ZPG ZPG Structure size Steel Catch Basin Steel Catch Basin Approximate Price $5,500 $5,500 Assumptions: • Media = ZPG cartridges providing basic treatment • Drop required from rim to outlet = 2.3’ minimum – 4.25’ maximum Size and cost estimates: The StormFilter is a flow-based system, and is therefore sized by calculating the peak water quality flow rate associated with the design storm. The water quality flow rates were calculated by the consulting engineer using WWHM and were provided to Contech Engineered Solutions LLC for the purposes of developing this estimate. The StormFilters for this site were sized based on the above water quality flow rates. To accommodate these flow rates, Contech Engineered Solutions recommends using catch basin StormFilters (see attached detail). The estimated cost of these systems is shown in the above table; these estimates include complete systems delivered to the job site. The final system cost will depend on the actual depth of the units and whether extras like doors rather than castings are specified. The contractor is responsible for setting the catch basin StormFilter and all external plumbing. Typically the catch basin StormFilters have internal bypass capacities of 1.0 cfs. Since the peak discharge in the basins is not expected to exceed this rate, a high-flow bypass upstream of the StormFilter systems is not required. CONTECH Stormwater Solutions Inc. Engineer:MSG Date 1/12/2018 Site Information West Basin Project Name Fire Station 15 Project State Washington Project Location Renton Drainage Area, Ad 0.095 ac Impervious Area, Ai 0.095 ac Pervious Area, Ap 0.00 % Impervious 100% Runoff Coefficient, Rc 0.95 Water quality flow 0.014 cfs Peak storm flow 0.096 cfs Filter System Filtration brand StormFilter Cartridge height 18 in Specific Flow Rate 1.00 gpm/ft2 Flow rate per cartridge 7.5 gpm SUMMARY Number of Cartridges 1 Determining Number of Cartridges for Flow Based Systems ©2006 CONTECH Stormwater Solutions contechstormwater.com 1 of 1 CONTECH Stormwater Solutions Inc. Engineer:MSG Date 1/12/2018 Site Information East Basin Project Name Fire Station 15 Project State Washington Project Location Renton Drainage Area, Ad 0.029 ac Impervious Area, Ai 0.029 ac Pervious Area, Ap 0.00 % Impervious 100% Runoff Coefficient, Rc 0.95 Water quality flow 0.004 cfs Peak storm flow 0.029 cfs Filter System Filtration brand StormFilter Cartridge height 18 in Specific Flow Rate 1.00 gpm/ft2 Flow rate per cartridge 7.5 gpm SUMMARY Number of Cartridges 1 Determining Number of Cartridges for Flow Based Systems ©2006 CONTECH Stormwater Solutions contechstormwater.com 1 of 1 ————————————————————————————————— MGS FLOOD PROJECT REPORT – Conveyance Analysis Program Version: MGSFlood 4.46 Program License Number: 201410003 Project Simulation Performed on: 01/24/2018 10:05 AM Report Generation Date: 01/24/2018 10:05 AM ————————————————————————————————— Input File Name: 2018-01-24 Conveyance Calcs.fld Project Name: FS 15 Analysis Title: Conveyance Comments: ———————————————— PRECIPITATION INPUT ———————————————— Computational Time Step (Minutes): 5 Extended Precipitation Time Series Selected Climatic Region Number: 15 Full Period of Record Available used for Routing Precipitation Station : 96004005 Puget East 40 in_5min 10/01/1939-10/01/2097 Evaporation Station : 961040 Puget East 40 in MAP Evaporation Scale Factor : 0.750 HSPF Parameter Region Number: 1 HSPF Parameter Region Name : USGS Default ********** Default HSPF Parameters Used (Not Modified by User) *************** ********************** WATERSHED DEFINITION *********************** Predevelopment/Post Development Tributary Area Summary Predeveloped Post Developed Total Subbasin Area (acres) 0.736 0.736 Area of Links that Include Precip/Evap (acres) 0.000 0.000 Total (acres) 0.736 0.736 ----------------------SCENARIO: PREDEVELOPED Number of Subbasins: 1 ---------- Subbasin : Pre-dev Basin ---------- -------Area (Acres) -------- Till Grass 0.736 ---------------------------------------------- Subbasin Total 0.736 ----------------------SCENARIO: POSTDEVELOPED Number of Subbasins: 1 ---------- Subbasin : Subbasin 1 ---------- -------Area (Acres) -------- Impervious 0.736 ---------------------------------------------- Subbasin Total 0.736 ************************* LINK DATA ******************************* ----------------------SCENARIO: PREDEVELOPED Number of Links: 1 ------------------------------------------ Link Name: New Copy Lnk1 Link Type: Copy Downstream Link: None ************************* LINK DATA ******************************* ----------------------SCENARIO: POSTDEVELOPED Number of Links: 0 **********************FLOOD FREQUENCY AND DURATION STATISTICS******************* ----------------------SCENARIO: PREDEVELOPED Number of Subbasins: 1 Number of Links: 1 ----------------------SCENARIO: POSTDEVELOPED Number of Subbasins: 1 Number of Links: 0 ***********Groundwater Recharge Summary ************* Recharge is computed as input to Perlnd Groundwater Plus Infiltration in Structures Total Predeveloped Recharge During Simulation Model Element Recharge Amount (ac-ft) ----------------------------------------------------------------------------------------------- Subbasin: Pre-dev Basin 89.884 Link: New Copy Lnk1 0.000 _____________________________________ Total: 89.884 Total Post Developed Recharge During Simulation Model Element Recharge Amount (ac-ft) ----------------------------------------------------------------------------------------------- Subbasin: Subbasin 1 0.000 _____________________________________ Total: 0.000 Total Predevelopment Recharge is Greater than Post Developed Average Recharge Per Year, (Number of Years= 158) Predeveloped: 0.569 ac-ft/year, Post Developed: 0.000 ac-ft/year ***********Water Quality Facility Data ************* ----------------------SCENARIO: PREDEVELOPED Number of Links: 1 ********** Link: New Copy Lnk1 ********** Infiltration/Filtration Statistics-------------------- Inflow Volume (ac-ft): 148.03 Inflow Volume Including PPT-Evap (ac-ft): 148.03 Total Runoff Infiltrated (ac-ft): 0.00, 0.00% Total Runoff Filtered (ac-ft): 0.00, 0.00% Primary Outflow To Downstream System (ac-ft): 148.03 Secondary Outflow To Downstream System (ac-ft): 0.00 Percent Treated (Infiltrated+Filtered)/Total Volume: 0.00% ----------------------SCENARIO: POSTDEVELOPED Number of Links: 0 ***********Compliance Point Results ************* Scenario Predeveloped Compliance Link: New Copy Lnk1 Scenario Postdeveloped Compliance Subbasin: Subbasin 1 *** Point of Compliance Flow Frequency Data *** Recurrence Interval Computed Using Gringorten Plotting Position Predevelopment Runoff Postdevelopment Runoff Tr (Years) Discharge (cfs) Tr (Years) Discharge (cfs) ---------------------------------------------------------------------------------------------------------------------- 2-Year 8.879E-02 2-Year 0.344 5-Year 0.165 5-Year 0.451 10-Year 0.221 10-Year 0.552 25-Year 0.336 25-Year 0.709 50-Year 0.441 50-Year 0.863 100-Year 0.578 100-Year 1.068 200-Year 0.588 200-Year 1.171 ** Record too Short to Compute Peak Discharge for These Recurrence Intervals Fire Station 15 1/22/2018 Conveyance Analysis Spreadsheet Gravity Discharge Pipe Run Size Mannings N Plan Slope Qfull Tributary Basins Tributary Area Impervious Grass Qtrib (25yr-5min) % Full (25yr) #(inches)(ft/ft)(cfs)(acres)(acres)(acres)(cfs) 1 Pipe Connecting to Point of Discharge 12 0.011 0.005 2.99 Entire Project Site 0.736 0.736 0.000 0.709 24% ————————————————————————————————— MGS FLOOD PROJECT REPORT – Erosion and Sediment Control Program Version: MGSFlood 4.45 Program License Number: 201410003 Project Simulation Performed on: 01/05/2018 2:29 PM Report Generation Date: 01/05/2018 2:29 PM ————————————————————————————————— Input File Name: Erosion calcs.fld Project Name: FS 15 Analysis Title: Erosion Calculations Comments: ———————————————— PRECIPITATION INPUT ———————————————— Computational Time Step (Minutes): 15 Extended Precipitation Time Series Selected Climatic Region Number: 15 Full Period of Record Available used for Routing Precipitation Station : 96004005 Puget East 40 in_5min 10/01/1939-10/01/2097 Evaporation Station : 961040 Puget East 40 in MAP Evaporation Scale Factor : 0.750 HSPF Parameter Region Number: 1 HSPF Parameter Region Name : USGS Default ********** Default HSPF Parameters Used (Not Modified by User) *************** ********************** WATERSHED DEFINITION *********************** Predevelopment/Post Development Tributary Area Summary Predeveloped Post Developed Total Subbasin Area (acres) 0.294 0.294 Area of Links that Include Precip/Evap (acres) 0.000 0.000 Total (acres) 0.294 0.294 ----------------------SCENARIO: PREDEVELOPED Number of Subbasins: 1 ---------- Subbasin : Subbasin 1 ---------- -------Area (Acres) -------- Till Forest 0.294 ---------------------------------------------- Subbasin Total 0.294 ----------------------SCENARIO: POSTDEVELOPED Number of Subbasins: 1 ---------- Subbasin : Subbasin 1 ---------- -------Area (Acres) -------- Impervious 0.294 ---------------------------------------------- Subbasin Total 0.294 ************************* LINK DATA ******************************* ----------------------SCENARIO: PREDEVELOPED Number of Links: 0 ************************* LINK DATA ******************************* ----------------------SCENARIO: POSTDEVELOPED Number of Links: 0 **********************FLOOD FREQUENCY AND DURATION STATISTICS******************* ----------------------SCENARIO: PREDEVELOPED Number of Subbasins: 1 Number of Links: 0 ----------------------SCENARIO: POSTDEVELOPED Number of Subbasins: 1 Number of Links: 0 ***********Groundwater Recharge Summary ************* Recharge is computed as input to Perlnd Groundwater Plus Infiltration in Structures Total Predeveloped Recharge During Simulation Model Element Recharge Amount (ac-ft) ----------------------------------------------------------------------------------------------- Subbasin: Subbasin 1 50.746 _____________________________________ Total: 50.746 Total Post Developed Recharge During Simulation Model Element Recharge Amount (ac-ft) ----------------------------------------------------------------------------------------------- Subbasin: Subbasin 1 0.000 _____________________________________ Total: 0.000 Total Predevelopment Recharge is Greater than Post Developed Average Recharge Per Year, (Number of Years= 158) Predeveloped: 0.321 ac-ft/year, Post Developed: 0.000 ac-ft/year ***********Water Quality Facility Data ************* ----------------------SCENARIO: PREDEVELOPED Number of Links: 0 ----------------------SCENARIO: POSTDEVELOPED Number of Links: 0 ***********Compliance Point Results ************* Scenario Predeveloped Compliance Subbasin: Subbasin 1 Scenario Postdeveloped Compliance Subbasin: Subbasin 1 *** Point of Compliance Flow Frequency Data *** Recurrence Interval Computed Using Gringorten Plotting Position Predevelopment Runoff Postdevelopment Runoff Tr (Years) Discharge (cfs) Tr (Years) Discharge (cfs) ---------------------------------------------------------------------------------------------------------------------- 2-Year 6.271E-03 2-Year 0.110 5-Year 1.022E-02 5-Year 0.142 10-Year 1.377E-02 10-Year 0.160 25-Year 1.746E-02 25-Year 0.202 50-Year 2.228E-02 50-Year 0.257 100-Year 2.415E-02 100-Year 0.297 200-Year 3.759E-02 200-Year 0.308 ** Record too Short to Compute Peak Discharge for These Recurrence Intervals Sediment Sizing Calculations Per City of Renton Surface Water Design Manual 2016 Section D.2.1.5.1 Project Name:Fire Station 15 Required Sediment Trap Surface Area (SA): SA =2*Q/Vsed Where:Q = Vsed =Settling Velocity (0.00096 ft/sec) Calculation:multiplier =2 Q =0.1100 cfs Vsed =0.00096 fps Required SA =229.2 square feet Equivalent Sediment Trap Volume: Length of Top Surface Area =23 feet Width of Top Surface Area =10 feet Surface Area Provided =230 square feet Side Slope =0 (H:1V) Total Depth of Sediment Trap =3.5 feet Bottom Length of Sediment Trap =23 feet Bottom Width of Sediment Trap =10 feet Total pond Volume =805 cubic feet6021.4 gallons 2-year developed flow rate from MGS Flood with SPU 158-year 5-minute time series To determine the minimum sediment trap volume, an equivalent sediment trap was sized based upon the required surface area. ————————————————————————————————— MGS FLOOD PROJECT REPORT – CONVEYANCE 8-INCH Program Version: MGSFlood 4.46 Program License Number: 201410003 Project Simulation Performed on: 01/29/2018 10:14 AM Report Generation Date: 01/29/2018 10:15 AM ————————————————————————————————— Input File Name: 2018-01-29 Conveyance Calcs - 8inch.fld Project Name: FS 15 Analysis Title: Conveyance Comments: ———————————————— PRECIPITATION INPUT ———————————————— Computational Time Step (Minutes): 5 Extended Precipitation Time Series Selected Climatic Region Number: 15 Full Period of Record Available used for Routing Precipitation Station : 96004005 Puget East 40 in_5min 10/01/1939-10/01/2097 Evaporation Station : 961040 Puget East 40 in MAP Evaporation Scale Factor : 0.750 HSPF Parameter Region Number: 1 HSPF Parameter Region Name : USGS Default ********** Default HSPF Parameters Used (Not Modified by User) *************** ********************** WATERSHED DEFINITION *********************** Predevelopment/Post Development Tributary Area Summary Predeveloped Post Developed Total Subbasin Area (acres) 0.736 0.736 Area of Links that Include Precip/Evap (acres) 0.000 0.000 Total (acres) 0.736 0.736 ----------------------SCENARIO: PREDEVELOPED Number of Subbasins: 1 ---------- Subbasin : Pre-dev Basin ---------- -------Area (Acres) -------- Till Grass 0.736 ---------------------------------------------- Subbasin Total 0.736 ----------------------SCENARIO: POSTDEVELOPED Number of Subbasins: 1 ---------- Subbasin : Subbasin 1 ---------- -------Area (Acres) -------- Till Grass 0.207 Impervious 0.528 ---------------------------------------------- Subbasin Total 0.736 ************************* LINK DATA ******************************* ----------------------SCENARIO: PREDEVELOPED Number of Links: 1 ------------------------------------------ Link Name: New Copy Lnk1 Link Type: Copy Downstream Link: None ************************* LINK DATA ******************************* ----------------------SCENARIO: POSTDEVELOPED Number of Links: 0 **********************FLOOD FREQUENCY AND DURATION STATISTICS******************* ----------------------SCENARIO: PREDEVELOPED Number of Subbasins: 1 Number of Links: 1 ----------------------SCENARIO: POSTDEVELOPED Number of Subbasins: 1 Number of Links: 0 ***********Groundwater Recharge Summary ************* Recharge is computed as input to Perlnd Groundwater Plus Infiltration in Structures Total Predeveloped Recharge During Simulation Model Element Recharge Amount (ac-ft) ----------------------------------------------------------------------------------------------- Subbasin: Pre-dev Basin 89.848 Link: New Copy Lnk1 0.000 _____________________________________ Total: 89.848 Total Post Developed Recharge During Simulation Model Element Recharge Amount (ac-ft) ----------------------------------------------------------------------------------------------- Subbasin: Subbasin 1 25.329 _____________________________________ Total: 25.329 Total Predevelopment Recharge is Greater than Post Developed Average Recharge Per Year, (Number of Years= 158) Predeveloped: 0.569 ac-ft/year, Post Developed: 0.160 ac-ft/year ***********Water Quality Facility Data ************* ----------------------SCENARIO: PREDEVELOPED Number of Links: 1 ********** Link: New Copy Lnk1 ********** Infiltration/Filtration Statistics-------------------- Inflow Volume (ac-ft): 147.97 Inflow Volume Including PPT-Evap (ac-ft): 147.97 Total Runoff Infiltrated (ac-ft): 0.00, 0.00% Total Runoff Filtered (ac-ft): 0.00, 0.00% Primary Outflow To Downstream System (ac-ft): 147.97 Secondary Outflow To Downstream System (ac-ft): 0.00 Percent Treated (Infiltrated+Filtered)/Total Volume: 0.00% ----------------------SCENARIO: POSTDEVELOPED Number of Links: 0 ***********Compliance Point Results ************* Scenario Predeveloped Compliance Link: New Copy Lnk1 Scenario Postdeveloped Compliance Subbasin: Subbasin 1 *** Point of Compliance Flow Frequency Data *** Recurrence Interval Computed Using Gringorten Plotting Position Predevelopment Runoff Postdevelopment Runoff Tr (Years) Discharge (cfs) Tr (Years) Discharge (cfs) ---------------------------------------------------------------------------------------------------------------------- 2-Year 8.875E-02 2-Year 0.271 5-Year 0.164 5-Year 0.358 10-Year 0.221 10-Year 0.430 25-Year 0.336 25-Year 0.565 50-Year 0.441 50-Year 0.757 100-Year 0.577 100-Year 0.928 200-Year 0.588 200-Year 0.990 ** Record too Short to Compute Peak Discharge for These Recurrence Intervals Fire Station 15 1/29/2018 Conveyance Analysis Spreadsheet Gravity Discharge Pipe Run Size Mannings N Plan Slope Qfull Tributary Basins Tributary Area Impervious Grass Qtrib (100yr-5min) % Full (25yr) #(inches)(ft/ft)(cfs)(acres)(acres)(acres)(cfs) 1 Pipe Connecting to Point of Discharge 8 0.011 0.005 1.01 Entire Project Site 0.736 0.528 0.208 0.928 92% NOTE: ON-SITE 8-INCH PIPE HAS BEEN EVALUATED TO DETERMINE CAPACITY USING THE 100 YEAR STORM PEAK FLOW. CALCULATIONS FOR THE 12- INCH PIPE DISCHARGING INTO THE ROW INCLUDE TOTAL SITE AS IMPERVIOUS AREA FOR CONSERVATIVE REASONS. Fire Station 15 Technical Information Report November 8, 2017; Revised January 25, 2018 APPENDIX C Stormwater Pollution Prevention and Spill Plan (SWPPS) Fire Station 15 Page 1 TIR - SWPPS Plan & Report LPD Engineering, PLLC November 10, 2017 FIRE STATION 15 STORMWATER POLLUTION PREVENTION AND SPILL PLAN REPORT The following report is in accordance with the City of Renton 2016 Surface Water Design Manual Amendment and the 2016 King County Surface Water Design Manual Section 2.3.1.4 for the Stormwater Pollution Prevention and Spill (SWPPS) Plan. The following is a summary of the items to be addressed on the TESC Plan, Sheet C1.01 of the contract documents and an indication of their applicability to this project. PART A: ACTIVITY SPECIFIC INFORMATION REQUIRED: Storage and Handling of Liquids: No petroleum products, fuel, solvents, detergents, pesticides, and concrete admixtures are expected to be stored on site. There may be small quantities of paint or form oil stored on site during construction. They are expected to be stored in a protected area such as inside a construction trailer, or inside a fenced enclosure in the contractor’s work area. Exact quantities and storage locations are not known at this time. Storage and Stockpiling of Construction Materials and Wastes: Construction materials and waste is not expected to be stockpiled on site during this project. They will be hauled off regularly. Fueling: Fueling of construction equipment shall be done by a mobile fuel truck and shall be allowed only in paved areas. Contractor shall provide a plan for fueling area spill containment to the Owner’s Representative and the City of Renton with a proposed method of secondary containment. The Owner’s Representative and the City of Renton shall review and approve plan prior to fueling. All spills, containment, and clean up shall be the contractor’s responsibility and at their own expense. Maintenance, Repairs, and Storage of Vehicles and Equipment: Equipment that requires significant repair will be removed from the site to repair. Minor repairs or maintenance may be allowed on site only in an approved area. Refer to note 6 in Part C below for additional information. Concrete Saw Cutting, Slurry, and Washwater Disposal: The project may require very limited quantities of concrete sawcutting. Concrete truck washout will not be allowed on site. Fire Station 15 Page 2 TIR - SWPPS Plan & Report LPD Engineering, PLLC November 10, 2017 Handling of pH Elevated Water: Monitoring for elevated pH may be required due to the amount of concrete work that is proposed. If so, the project specifications will include pH monitoring requirements and treatment. Application of Chemicals including Pesticides and Fertilizers: No chemicals are expected to be used in this project. PART B: SWPPS SITE PLAN: Refer to Sheet C1.01 of the drawings. PART C: POLLUTION PREVENTION REPORT: 1. Liquids including petroleum products, fuel, solvents, detergents, pesticides, and concrete admixtures are not anticipated to be stored on site. If products such as fuel are required, these items will be brought in small quantities, used, and removed from the site. Items such as paint or form oils, if needed, will be delivered to the site in small quantities and stored inside a construction trailer prior to use. No hazardous liquid products including but not limited to petroleum products, fuel, solvents, detergents, paint, pesticides, concrete admixtures and form oils shall be stored on-site without prior approval. If requested, the Contractor shall provide for spill containment in accordance with City of Renton requirements. Contractor shall provide a list of the types and sizes of liquids that will be stored/handled on site. Contractor will also show the proposed location for storage on a project site plan and will provide a proposed method of secondary containment. The Owner’s Representative and the City shall review and approve plan prior to storage. 2. Any demolished material will be removed immediately upon demolition. This project has no hazardous material to be removed. Construction waste shall be promptly removed from the site and shall not be stockpiled. 3. No stationary tanks will be used for this project. 4. If required, a mobile fuel truck will be brought to the site to fuel the excavation equipment. Fueling of construction equipment shall by a mobile fuel truck and shall be allowed only in paved areas. Contractor shall provide a plan for fueling area spill containment to the Owner’s Representative and the City of Renton with a proposed method of secondary containment. The Owner’s Representative and the City shall review and approve plan prior to fueling. All spills, containment, and clean up shall be the contractor’s responsibility and at their own expense. 5. Equipment will only be fueled during daylight hours. 6. Equipment that requires significant repair will be removed from the site to repair. Minor repairs or maintenance may be allowed on site only in an approved area. The Contractor shall remove from the site all equipment that requires significant repair. Minor repairs or maintenance may be allowed on site in an approved area. The Contractor shall submit a plan for the proposed location of vehicle Fire Station 15 Page 3 TIR - SWPPS Plan & Report LPD Engineering, PLLC November 10, 2017 maintenance and repair and shall indicate the proposed method of containment for possible leaking vehicle fluids. The contractor shall also provide a plan to the Owner’s Representative and the City of Renton for the collection, storage and disposal of the vehicle fluids. The Owner’s Representative and the City shall review and approve plan prior to any on-site maintenance. 7. Truck Washout will not be allowed on site. 8. No chemicals are anticipated to be required for this project. 9. Selected Contractor shall provide location for spill response materials, and identify disposal methods for contaminated water and soil after a spill. Contractor shall provide to the Owner’s representative and the City of Renton the location of spill response materials. Contractor will also identify disposal methods for contaminated water and soil after a spill. 10. The project will be publicly bid thus no excavation contractor is currently under contract. Due to the limited size and scope of this project, the possible sources of pollution are limited and are addressed above. In addition to the above information provided on the contract documents, the following are to specifically address pollution prevention: • The Contractor shall provide a report to the Owner’s Representative and the City of Renton identifying the personnel responsible for pollution prevention, including contact information, and clearly listing the responsibilities of these personnel. • The Contractor shall also provide a description of the procedures to be used in monitoring the prevention BMP and responding to the BMP including record keeping. Fire Station 15 Page 4 TIR - SWPPS Plan & Report LPD Engineering, PLLC November 10, 2017 PART D: SPILL PREVENTION AND CLEANUP REPORT: An excavation contractor is not yet under contract for this project. Spill prevention is addressed with notes on the contract documents as stated above. Since the size and scope of this project is limited, the sources of potential spills are very limited and have been addressed on the plan with notes. In addition to the above information provided on the contract documents, the following notes specifically address spill prevention: • The Contractor shall provide a report to the Owner’s Representative and the City of Renton identifying the personnel responsible for spill prevention, including contact information, and clearly listing the responsibilities of these personnel. • The Contractor shall provide a description of the procedures to be used in monitoring the spill prevention BMPs and responding to the BMPs, including record keeping. Fire Station 15 Technical Information Report Submitted: November 10, 2017; Revised: February 12, 2018 APPENDIX D Operations and Maintenance Manual Stormwater Solutions from Contech® www.ContechES.com/stormwater 800-338-1122 © 2013 Contech Engineered Solutions Page 1 ENGINEERED SOLUTIONS OperatiOn and Maintenance catchBasin StormFilter™ Important: These guidelines should be used as a part of your site stormwater plan. Overview The CatchBasin StormFilter™ (CBSF) consists of a multi-chamber steel, concrete, or plastic catch basin unit that can contain up to four StormFilter cartridges. The steel CBSF is offered both as a standard and as a deep unit. The CBSF is installed flush with the finished grade and is applicable for both constrained lot and retrofit applications. It can also be fitted with an inlet pipe for roof leaders or similar applications. The CBSF unit treats peak water quality design flows up to 0.13 cfs, coupled with an internal weir overflow capacity of 1.0 cfs for the standard unit, and 1.8 cfs for the deep steel and concrete units. Plastic units have an internal weir overflow capacity of 0.5 cfs. Design Operation The CBSF is installed as the primary receiver of runoff, similar to a standard, grated catch basin. The steel and concrete CBSF units have an H-20 rated, traffic bearing lid that allows the filter to be installed in parking lots, and for all practical purposes, takes up no land area. Plastic units can be used in landscaped areas and for other non-traffic-bearing applications. The CBSF consists of a sumped inlet chamber and a cartridge chamber(s). Runoff enters the sumped inlet chamber either by sheet flow from a paved surface or from an inlet pipe discharging directly to the unit vault. The inlet chamber is equipped with an internal baffle, which traps debris and floating oil and grease, and an overflow weir. While in the inlet chamber, heavier solids are allowed to settle into the deep sump, while lighter solids and soluble pollutants are directed under the baffle and into the cartridge chamber through a port between the baffle and the overflow weir. Once in the cartridge chamber, polluted water ponds and percolates horizontally through the media in the filter cartridges. Treated water collects in the cartridge’s center tube from where it is directed by an under-drain manifold to the outlet pipe on the downstream side of the overflow weir and discharged. When flows into the CBSF exceed the water quality design value, excess water spills over the overflow weir, bypassing the cartridge bay, and discharges to the outlet pipe. Applications The CBSF is particularly useful where small flows are being treated or for sites that are flat and have little available hydraulic head to spare. The unit is ideal for applications in which standard catch basins are to be used. Both water quality and catchment issues can be resolved with the use of the CBSF. Retro-Fit The retrofit market has many possible applications for the CBSF. The CBSF can be installed by replacing an existing catch basin without having to “chase the grade,” thus reducing the high cost of re piping the storm system. Stormwater Solutions from Contech® www.ContechES.com/stormwater 800-338-1122 © 2013 Contech Engineered Solutions Page 2 ENGINEERED SOLUTIONS OperatiOn and Maintenance catchBasin StormFilter™ Maintenance Guidelines Maintenance procedures for typical catch basins can be applied to the CatchBasin StormFilter (CBSF). The filter cartridges contained in the CBSF are easily removed and replaced during maintenance activities according to the following guidelines. 1. Establish a safe working area as per typical catch basin service activity. 2. Remove steel grate and diamond plate cover (weight 100 lbs. each). 3. Turn cartridge(s) counter-clockwise to disconnect from pipe manifold. 4. Remove 4” center cap from cartridge and replace with lifting cap. 5. Remove cartridge(s) from catch basin by hand or with vactor truck boom. 6. Remove accumulated sediment via vactor truck (min. clearance 13” x 24”). 7. Remove accumulated sediment from cartridge bay. (min. clearance 9.25” x 11”). 8. Rinse interior of both bays and vactor remaining water and sediment. 9. Install fresh cartridge(s) threading clockwise to pipe manifold. 10. Replace cover and grate. 11. Return original cartridges to Contech for cleaning. Media may be removed from the filter cartridges using the vactor truck before the cartridges are removed from the catch basin structure. Empty cartridges can be easily removed from the catch basin structure by hand. Empty cartridges should be reassembled and returned to Contech as appropriate. Materials required include a lifting cap, vactor truck and fresh filter cartridges. Contact Contech for specifications and availability of the lifting cap. The vactor truck must be equipped with a hose capable of reaching areas of restricted clearance. the owner may refresh spent cartridges. Refreshed cartridges are also available from Contech on an exchange basis. Contact the maintenance department of Contech at 503-258-3157 for more information. Maintenance is estimated at 26 minutes of site time. For units with more than one cartridge, add approximately 5 minutes for each additional cartridge. Add travel time as required. Mosquito Abatement In certain areas of the United States, mosquito abatement is desirable to reduce the incidence of vectors. In BMPs with standing water, which could provide mosquito breeding habitat, certain abatement measures can be taken. 1. Periodic observation of the standing water to determine if the facility is harboring mosquito larvae. 2. Regular catch basin maintenance. 3. Use of larvicides containing Bacillus thuringiensis israelensis (BTI). BTI is a bacterium toxic to mosquito and black fly larvae. In some cases, the presence of petroleum hydrocarbons may interrupt the mosquito growth cycle. Using Larvicides in the CatchBasin StormFilter Larvicides should be used according to manufacturer’s recommendations. Two widely available products are Mosquito Dunks and Summit B.t.i. Briquets. For more information, visit http://www. summitchemical.com/mos_ctrl/d efault.htm. The larvicide must be in contact with the permanent pool. The larvicide should also be fastened to the CatchBasin StormFilter by string or wire to prevent displacement by high flows. A magnet can be used with a steel catch basin. For more information on mosquito abatement in stormwater BMPs, refer to the following: http://www.ucmrp.ucdavis.edu/ publications/managingmosquitoesstormwater8125.pdf APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 12/12/2016 2017 City of Renton Surface Water Design Manual A-4 NO. 2 – INFILTRATION FACILITIES MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Site Trash and debris Any trash and debris which exceed 1 cubic foot 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. Trash and debris cleared from site. Noxious weeds Any noxious or nuisance vegetation which may constitute a hazard to City personnel or the public. Noxious and nuisance vegetation removed according to applicable regulations. No danger of noxious vegetation where City personnel or the public might normally be. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Excessive growth of grass/groundcover Grass or groundcover exceeds 18 inches in height. Grass or groundcover mowed to a height no greater than 6 inches. Infiltration Pond, Top or Side Slopes of Dam, Berm or Embankment Rodent holes Any evidence of rodent holes if facility is acting as a dam or berm, or any evidence of water piping through dam or berm via rodent holes. Rodents removed or destroyed and dam or berm repaired. Tree growth Tree growth threatens integrity of dams, berms or slopes, does not allow maintenance access, or interferes with maintenance activity. If trees are not a threat to dam, berm, or embankment integrity or not interfering with access or maintenance, they do not need to be removed. Trees do not hinder facility performance or maintenance activities. Erosion Eroded damage over 2 inches deep where cause of damage is still present or where there is potential for continued erosion. Any erosion observed on a compacted slope. Slopes stabilized using appropriate erosion control measures. If erosion is occurring on compacted slope, a licensed civil engineer should be consulted to resolve source of erosion. Settlement Any part of a dam, berm or embankment that has settled 4 inches lower than the design elevation. Top or side slope restored to design dimensions. If settlement is significant, a licensed civil engineer should be consulted to determine the cause of the settlement. Infiltration Pond, Tank, Vault, Trench, or Small Basin Storage Area Sediment accumulation If two inches or more sediment is present or a percolation test indicates facility is working at or less than 90% of design. Facility infiltrates as designed. Liner damaged (If applicable) Liner is visible or pond does not hold water as designed. Liner repaired or replaced. Infiltration Tank Structure Plugged air vent Any blockage of the vent. Tank or vault freely vents. Tank bent out of shape Any part of tank/pipe is bent out of shape more than 10% of its design shape. Tank repaired or replaced to design. Gaps between sections, damaged joints or cracks or tears in wall A gap wider than ½-inch at the joint of any tank sections or any evidence of soil particles entering the tank at a joint or through a wall. No water or soil entering tank through joints or walls. Infiltration Vault Structure Damage to wall, frame, bottom, and/or top slab Cracks wider than ½-inch, any evidence of soil entering the structure through cracks or qualified inspection personnel determines that the vault is not structurally sound. Vault is sealed and structurally sound. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 2017 City of Renton Surface Water Design Manual 12/12/2016 A-5 NO. 2 – INFILTRATION FACILITIES MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Inlet/Outlet Pipes Sediment accumulation Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment. Trash and debris Trash and debris accumulated in inlet/outlet pipes (includes floatables and non-floatables). No trash or debris in pipes. Damaged inlet/outlet pipe Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering at the joints of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of the inlet/outlet pipe. Access Manhole Cover/lid not in place Cover/lid is missing or only partially in place. Any open manhole requires immediate maintenance. Manhole access covered. Locking mechanism not working Mechanism cannot be opened by one maintenance person with proper tools. Bolts cannot be seated. Self-locking cover/lid does not work. Mechanism opens with proper tools. Cover/lid difficult to remove One maintenance person cannot remove cover/lid after applying 80 lbs of lift. Cover/lid can be removed and 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 doors/plate Damaged or difficult to open Large access doors or plates cannot be opened/removed using normal equipment. Replace or repair access door so it can opened as designed. Gaps, doesn't cover completely Large access doors not flat and/or access opening not completely covered. Doors close flat; covers access opening completely. Lifting rings missing, rusted Lifting rings not capable of lifting weight of door or plate. Lifting rings sufficient to lift or remove door or plate. Infiltration Pond, Tank, Vault, Trench, or Small Basin Filter Bags Plugged filter bag (if applicable) Filter bag more than 1/2 full. Replace filter bag or redesign system. Infiltration Pond, Tank, Vault, Trench, or Small Basin Pre- settling Ponds and Vaults Sediment accumulation 6" or more of sediment has accumulated. Pre-settling occurs as designed Infiltration Pond, Rock Filter Plugged rock filter High water level on upstream side of filter remains for extended period of time or little or no water flows through filter during heavy rain storms. Rock filter replaced evaluate need for filter and remove if not necessary. Infiltration Pond Emergency Overflow Spillway Rock missing Only one layer of rock exists above native soil in area five square feet or larger, or any exposure of native soil at the top of out flow path of spillway. Rip-rap on inside slopes need not be replaced. Spillway restored to design standards. Tree growth Tree growth impedes flow or threatens stability of spillway. Trees removed. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 12/12/2016 2017 City of Renton Surface Water Design Manual A-6 NO. 3 – DETENTION TANKS AND VAULTS MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Site Trash and debris Any trash and debris which exceed 1 cubic foot 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. Trash and debris cleared from site. Noxious weeds Any noxious or nuisance vegetation which may constitute a hazard to City personnel or the public. Noxious and nuisance vegetation removed according to applicable regulations. No danger of noxious vegetation where City personnel or the public might normally be. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Excessive growth of grass/groundcover Grass or groundcover exceeds 18 inches in height. Grass or groundcover mowed to a height no greater than 6 inches. Tank or Vault Storage Area Trash and debris Any trash and debris accumulated in vault or tank (includes floatables and non- floatables). No trash or debris in vault. Sediment accumulation Accumulated sediment depth exceeds 10% of the diameter of the storage area for ½ length of storage vault or any point depth exceeds 15% of diameter. Example: 72-inch storage tank would require cleaning when sediment reaches depth of 7 inches for more than ½ length of tank. All sediment removed from storage area. Tank Structure Plugged air vent Any blockage of the vent. Tank or vault freely vents. Tank bent out of shape Any part of tank/pipe is bent out of shape more than 10% of its design shape. Tank repaired or replaced to design. Gaps between sections, damaged joints or cracks or tears in wall A gap wider than ½-inch at the joint of any tank sections or any evidence of soil particles entering the tank at a joint or through a wall. No water or soil entering tank through joints or walls. Vault Structure Damage to wall, frame, bottom, and/or top slab Cracks wider than ½-inch, any evidence of soil entering the structure through cracks or qualified inspection personnel determines that the vault is not structurally sound. Vault is sealed and structurally sound. Inlet/Outlet Pipes Sediment accumulation Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment. Trash and debris Trash and debris accumulated in inlet/outlet pipes (includes floatables and non-floatables). No trash or debris in pipes. Damaged inlet/outlet pipes Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering at the joints of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of the inlet/outlet pipe. Access Manhole Cover/lid not in place Cover/lid is missing or only partially in place. Any open manhole requires immediate maintenance. Manhole access covered. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 2017 City of Renton Surface Water Design Manual 12/12/2016 A-7 NO. 3 – DETENTION TANKS AND VAULTS MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Access Manhole (cont.) Locking mechanism not working Mechanism cannot be opened by one maintenance person with proper tools. Bolts cannot be seated. Self-locking cover/lid does not work. Mechanism opens with proper tools. Cover/lid difficult to remove One maintenance person cannot remove cover/lid after applying 80 lbs of lift. Cover/lid can be removed and 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 doors/plate Damaged or difficult to open Large access doors or plates cannot be opened/removed using normal equipment. Replace or repair access door so it can opened as designed. Gaps, doesn't cover completely Large access doors not flat and/or access opening not completely covered. Doors close flat; covers access opening completely. Lifting rings missing, rusted Lifting rings not capable of lifting weight of door or plate. Lifting rings sufficient to lift or remove door or plate. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 12/12/2016 2017 City of Renton Surface Water Design Manual A-8 NO. 4 – CONTROL STRUCTURE/FLOW RESTRICTOR MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITION WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Structure Trash and debris Trash or debris of more than ½ cubic foot which is located immediately in front of the structure opening or is blocking capacity of the structure by more than 10%. No Trash or debris blocking or potentially blocking entrance to structure. Trash or debris in the structure that exceeds 1/3 the depth from the bottom of basin to invert the lowest pipe into or out of the basin. No trash or debris in the structure. Deposits of garbage exceeding 1 cubic foot in volume. No condition present which would attract or support the breeding of insects or rodents. Sediment accumulation Sediment exceeds 60% of the depth from the bottom of the structure to the invert of the lowest pipe into or out of the structure or the bottom of the FROP-T section or is within 6 inches of the invert of the lowest pipe into or out of the structure or the bottom of the FROP-T section. Sump of structure contains no sediment. Damage to frame and/or top slab Corner of frame extends more than ¾ inch past curb face into the street (If applicable). Frame is even with curb. Top slab has holes larger than 2 square inches or cracks wider than ¼ inch. Top slab is free of holes and cracks. Frame not sitting flush on top slab, i.e., separation of more than ¾ inch of the frame from the top slab. Frame is sitting flush on top slab. Cracks in walls or bottom Cracks wider than ½ inch and longer than 3 feet, any evidence of soil particles entering structure through cracks, or maintenance person judges that structure is unsound. Structure is sealed and structurally sound. Cracks wider than ½ inch and longer than 1 foot at the joint of any inlet/outlet pipe or any evidence of soil particles entering structure through cracks. No cracks more than 1/4 inch wide at the joint of inlet/outlet pipe. Settlement/ misalignment Structure has settled more than 1 inch or has rotated more than 2 inches out of alignment. Basin replaced or repaired to design standards. Damaged pipe joints Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering the structure at the joint of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of inlet/outlet pipes. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Ladder rungs missing or unsafe Ladder is unsafe due to missing rungs, misalignment, rust, cracks, or sharp edges. Ladder meets design standards and allows maintenance person safe access. FROP-T Section Damaged FROP-T T section is not securely attached to structure wall and outlet pipe structure should support at least 1,000 lbs of up or down pressure. T section securely attached to wall and outlet pipe. Structure is not in upright position (allow up to 10% from plumb). Structure in correct position. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 2017 City of Renton Surface Water Design Manual 12/12/2016 A-9 NO. 4 – CONTROL STRUCTURE/FLOW RESTRICTOR MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITION WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED FROP-T Section (cont.) Damaged FROP-T (cont.) Connections to outlet pipe are not watertight or show signs of deteriorated grout. Connections to outlet pipe are water tight; structure repaired or replaced and works as designed. Any holes—other than designed holes—in the structure. Structure has no holes other than designed holes. Cleanout Gate Damaged or missing cleanout gate Cleanout gate is missing. Replace cleanout gate. Cleanout gate is not watertight. Gate is watertight and works as designed. Gate cannot be moved up and down by one maintenance person. Gate moves up and down easily and is watertight. Chain/rod leading to gate is missing or damaged. Chain is in place and works as designed. Orifice Plate Damaged or missing orifice plate Control device is not working properly due to missing, out of place, or bent orifice plate. Plate is in place and works as designed. Obstructions to orifice plate Any trash, debris, sediment, or vegetation blocking the plate. Plate is free of all obstructions and works as designed. Overflow Pipe Obstructions to overflow pipe Any trash or debris blocking (or having the potential of blocking) the overflow pipe. Pipe is free of all obstructions and works as designed. Deformed or damaged lip of overflow pipe Lip of overflow pipe is bent or deformed. Overflow pipe does not allow overflow at an elevation lower than design Inlet/Outlet Pipe Sediment accumulation Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment. Trash and debris Trash and debris accumulated in inlet/outlet pipes (includes floatables and non-floatables). No trash or debris in pipes. Damaged inlet/outlet pipe Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering at the joints of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of the inlet/outlet pipe. Metal Grates (If applicable) Unsafe grate opening Grate with opening wider than 7/8 inch. Grate opening meets design standards. Trash and debris Trash and debris that is blocking more than 20% of grate surface. Grate free of trash and debris. footnote to guidelines for disposal Damaged or missing grate Grate missing or broken member(s) of the grate. Grate is in place and meets design standards. Manhole Cover/Lid Cover/lid not in place Cover/lid is missing or only partially in place. Any open structure requires urgent maintenance. Cover/lid protects opening to structure. Locking mechanism not working Mechanism cannot be opened by one maintenance person with proper tools. Bolts cannot be seated. Self-locking cover/lid does not work. Mechanism opens with proper tools. Cover/lid difficult to remove One maintenance person cannot remove cover/lid after applying 80 lbs. of lift. Cover/lid can be removed and reinstalled by one maintenance person. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 12/12/2016 2017 City of Renton Surface Water Design Manual A-10 NO. 5 – CATCH BASINS AND MANHOLES MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITION WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Structure Sediment accumulation Sediment exceeds 60% of the depth from the bottom of the catch basin to the invert of the 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. Sump of catch basin contains no sediment. Trash and debris Trash or debris of more than ½ cubic foot which is located immediately in front of the catch basin opening or is blocking capacity of the catch basin by more than 10%. No Trash or debris blocking or potentially blocking entrance to catch basin. Trash or debris in the catch basin that exceeds 1/3 the depth from the bottom of basin to invert the lowest pipe into or out of the basin. No trash or debris in the catch basin. Dead animals or vegetation that could generate odors that could cause complaints or dangerous gases (e.g., methane). No dead animals or vegetation present within catch basin. Deposits of garbage exceeding 1 cubic foot in volume. No condition present which would attract or support the breeding of insects or rodents. Damage to frame and/or top slab Corner of frame extends more than ¾ inch past curb face into the street (If applicable). Frame is even with curb. Top slab has holes larger than 2 square inches or cracks wider than ¼ inch. Top slab is free of holes and cracks. Frame not sitting flush on top slab, i.e., separation of more than ¾ inch of the frame from the top slab. Frame is sitting flush on top slab. Cracks in walls or bottom Cracks wider than ½ inch and longer than 3 feet, any evidence of soil particles entering catch basin through cracks, or maintenance person judges that catch basin is unsound. Catch basin is sealed and is structurally sound. Cracks wider than ½ inch and longer than 1 foot at the joint of any inlet/outlet pipe or any evidence of soil particles entering catch basin through cracks. No cracks more than 1/4 inch wide at the joint of inlet/outlet pipe. Settlement/ misalignment Catch basin has settled more than 1 inch or has rotated more than 2 inches out of alignment. Basin replaced or repaired to design standards. Damaged pipe joints Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering the catch basin at the joint of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of inlet/outlet pipes. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Inlet/Outlet Pipe Sediment accumulation Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment. Trash and debris Trash and debris accumulated in inlet/outlet pipes (includes floatables and non-floatables). No trash or debris in pipes. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 2017 City of Renton Surface Water Design Manual 12/12/2016 A-11 NO. 5 – CATCH BASINS AND MANHOLES MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITION WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Inlet/Outlet Pipe (cont.) Damaged inlet/outlet pipe Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering at the joints of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of the inlet/outlet pipe. Metal Grates (Catch Basins) Unsafe grate opening Grate with opening wider than 7/8 inch. Grate opening meets design standards. Trash and debris Trash and debris that is blocking more than 20% of grate surface. Grate free of trash and debris. footnote to guidelines for disposal Damaged or missing grate Grate missing or broken member(s) of the grate. Any open structure requires urgent maintenance. Grate is in place and meets design standards. Manhole Cover/Lid Cover/lid not in place Cover/lid is missing or only partially in place. Any open structure requires urgent maintenance. Cover/lid protects opening to structure. Locking mechanism not working Mechanism cannot be opened by one maintenance person with proper tools. Bolts cannot be seated. Self-locking cover/lid does not work. Mechanism opens with proper tools. Cover/lid difficult to remove One maintenance person cannot remove cover/lid after applying 80 lbs. of lift. Cover/lid can be removed and reinstalled by one maintenance person. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 12/12/2016 2017 City of Renton Surface Water Design Manual A-12 NO. 6 – CONVEYANCE PIPES AND DITCHES MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Pipes Sediment & debris accumulation Accumulated sediment or debris that exceeds 20% of the diameter of the pipe. Water flows freely through pipes. Vegetation/root growth in pipe Vegetation/roots that reduce free movement of water through pipes. Water flows freely through pipes. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Damage to protective coating or corrosion Protective coating is damaged; rust or corrosion is weakening the structural integrity of any part of pipe. Pipe repaired or replaced. Damaged pipes Any dent that decreases the cross section area of pipe by more than 20% or is determined to have weakened structural integrity of the pipe. Pipe repaired or replaced. Ditches Trash and debris Trash and debris exceeds 1 cubic foot per 1,000 square feet of ditch and slopes. Trash and debris cleared from ditches. Sediment accumulation Accumulated sediment that exceeds 20% of the design depth. Ditch cleaned/flushed of all sediment and debris so that it matches design. Noxious weeds Any noxious or nuisance vegetation which may constitute a hazard to City personnel or the public. Noxious and nuisance vegetation removed according to applicable regulations. No danger of noxious vegetation where City personnel or the public might normally be. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Excessive vegetation growth Vegetation that reduces free movement of water through ditches. Water flows freely through ditches. Erosion damage to slopes Any erosion observed on a ditch slope. Slopes are not eroding. Rock lining out of place or missing (If applicable) One layer or less of rock exists above native soil area 5 square feet or more, any exposed native soil. Replace rocks to design standards. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 2017 City of Renton Surface Water Design Manual 12/12/2016 A-17 NO. 11 – GROUNDS (LANDSCAPING) MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Site Trash and debris Any trash and debris which exceed 1 cubic foot 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. Trash and debris cleared from site. Noxious weeds Any noxious or nuisance vegetation which may constitute a hazard to City personnel or the public. Noxious and nuisance vegetation removed according to applicable regulations. No danger of noxious vegetation where City personnel or the public might normally be. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Excessive growth of grass/groundcover Grass or groundcover exceeds 18 inches in height. Grass or groundcover mowed to a height no greater than 6 inches. Trees and Shrubs Hazard tree identified Any tree or limb of a tree identified as having a 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. No hazard trees in facility. Damaged tree or shrub identified Limbs or parts of trees or shrubs that are split or broken which affect more than 25% of the total foliage of the tree or shrub. Trees and shrubs with less than 5% of total foliage with split or broken limbs. Trees or shrubs that have been blown down or knocked over. No blown down vegetation or knocked over vegetation. Trees or shrubs free of injury. Trees or shrubs which are not adequately supported or are leaning over, causing exposure of the roots. Tree or shrub in place and adequately supported; dead or diseased trees removed. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 2017 City of Renton Surface Water Design Manual 12/12/2016 A-31 NO. 21 – PROPRIETARY FACILITY CARTRIDGE FILTER SYSTEMS MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITION WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED In addition to the specific maintenance criteria provided below, all manufacturers’ requirements shall be followed. Facility Documentation Update facility inspection record after each inspection. Maintenance records are up to date. Provide certification of replaced filter media. Filter media is certified to meet manufacturer specifications. Site Trash and debris Any trash or debris which impairs the function of the facility. Trash and debris removed from facility. Contaminants and pollution Any evidence of contaminants or pollution such as oils, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Life cycle Once per year. Facility is re-inspected and any needed maintenance performed. Vault Treatment Area Sediment on vault floor Varies – Refer to manufacturer’s requirements. Vault is free of sediment. Sediment on top of cartridges Varies – Refer to manufacturer’s requirements. Vault is free of sediment. Multiple scum lines above top of cartridges Thick or multiple scum lines above top of cartridges. Probably due to plugged canisters or underdrain manifold. Cause of plugging corrected, canisters replaced if necessary. Vault Structure Damage to wall, frame, bottom, and/or top slab Cracks wider than ½-inch and any evidence of soil particles entering the structure through the cracks, or qualified inspection personnel determines the vault is not structurally sound. Vault replaced or repaired to design specifications. Baffles damaged Baffles corroding, cracking warping, and/or showing signs of failure as determined by maintenance/inspection person. Repair or replace baffles to specification. Filter Media Standing water in vault Varies – Refer to manufacturer’s requirements. No standing water in vault 24 hours after a rain event. Short circuiting Flows do not properly enter filter cartridges. Flows go through filter media. Underdrains and Clean-Outs Sediment and debris Underdrains or clean-outs partially plugged or filled with sediment and/or debris. Underdrains and clean-outs free of sediment and debris. Inlet/Outlet Pipe Sediment accumulation Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment. Trash and debris Trash and debris accumulated in inlet/outlet pipes (includes floatables and non-floatables). No trash or debris in pipes. Damaged inlet/outlet pipe Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering at the joints of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of the inlet/outlet pipe. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 12/12/2016 2017 City of Renton Surface Water Design Manual A-32 NO. 21 – PROPRIETARY FACILITY CARTRIDGE FILTER SYSTEMS MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITION WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Access Manhole Cover/lid not in place Cover/lid is missing or only partially in place. Any open manhole requires immediate maintenance. Manhole access covered. Locking mechanism not working Mechanism cannot be opened by one maintenance person with proper tools. Bolts cannot be seated. Self-locking cover/lid does not work. Mechanism opens with proper tools. Cover/lid difficult to remove One maintenance person cannot remove cover/lid after applying 80 lbs of lift. Cover/lid can be removed and 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 Doors/Plate Damaged or difficult to open Large access doors or plates cannot be opened/removed using normal equipment. Replace or repair access door so it can opened as designed. Gaps, doesn't cover completely Large access doors not flat and/or access opening not completely covered. Doors close flat and cover access opening completely. Lifting Rings missing, rusted Lifting rings not capable of lifting weight of door or plate. Lifting rings sufficient to lift or remove door or plate. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 12/12/2016 2017 City of Renton Surface Water Design Manual A-40 NO. 28 – NATIVE VEGETATED SURFACE/NATIVE VEGETATED LANDSCAPE BMP MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITION WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Site Trash and debris Trash and debris accumulated on the native vegetated surface/native vegetated landscape site. Native vegetated surface site free of any trash or debris. Vegetation Insufficient vegetation Less than two species each of native trees, shrubs, and groundcover occur in the design area. A minimum of two species each of native trees, shrubs, and groundcover is established and healthy. Poor vegetation coverage Less than 90% if the required vegetated area has healthy growth. A minimum of 90% of the required vegetated area has healthy growth. Undesirable vegetation present Weeds, blackberry, and other undesirable plants are invading more than 10% of vegetated area. Less than 10% undesirable vegetation occurs in the required native vegetated surface area. Vegetated Area Soil compaction Soil in the native vegetation area compacted. Less than 8% of native vegetation area is compacted. Insufficient vegetation Less than 3.5 square feet of native vegetation area for every 1 square foot of impervious surface. A minimum of 3.5 square feet of native vegetation area for every 1 square foot of impervious surface. Excess slope Slope of native vegetation area greater than 15%. Slope of native growth area does not exceed 15%. NO. 29 – PERFORATED PIPE CONNECTIONS BMP MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Preventive Blocking, obstructions Debris or trash limiting flow into perforated pipe system or outfall of BMP is plugged or otherwise nonfunctioning. Outfall of BMP is receiving designed flows from perforated pipe connection. Inflow Inflow impeded Inflow into the perforated pipe is partially or fully blocked or altered to prevent flow from getting into the pipe. Inflow to the perforated pipe is unimpeded. Pipe Trench Area Surface compacted Ground surface over the perforated pipe trench is compacted or covered with impermeable material. Ground surface over the perforated pipe is not compacted and free of any impervious cover. Outflow Outflow impeded Outflow from the perforated pipe into the public drainage system is blocked. Outflow to the public drainage system is unimpeded. Outfall Area Erosion or landslides Existence of the perforated pipe is causing or exasperating erosion or landslides. Perforated pipe system is sealed off and an alternative BMP is implemented. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 2017 City of Renton Surface Water Design Manual 12/12/2016 A-41 NO. 30 – PERMEABLE PAVEMENT BMP MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Preventive Surface cleaning/ vegetation control Media surface vacuumed or pressure washed annually, vegetation controlled to design maximum. Weed growth suggesting sediment accumulation. No dirt, sediment, or debris clogging porous media, or vegetation limiting infiltration. Porous Concrete, Porous Asphaltic Concrete, and Permeable Pavers Trash and debris Trash and debris on the pavement interfering with infiltration; leaf drop in fall season. No trash or debris interfering with infiltration. Sediment accumulation Sediment accumulation on the pavement interfering with infiltration; runoff from adjacent areas depositing sediment/debris on pavement. Pavement infiltrates as designed; adjacent areas stabilized. Insufficient infiltration rate Pavement does not infiltrate at a rate of 10 inches per hour. Pavement infiltrates at a rate greater than 10 inches per hour. Excessive ponding Standing water for a long period of time on the surface of the pavement. Standing water infiltrates at the desired rate. Broken or cracked pavement Pavement is broken or cracked. No broken pavement or cracks on the surface of the pavement. Settlement Uneven pavement surface indicating settlement of the subsurface layer. Pavement surface is uniformly level. Moss growth Moss growing on pavement interfering with infiltration. No moss interferes with infiltration. Inflow restricted Inflow to the pavement is diverted, restricted, or depositing sediment and debris on the pavement. Inflow to pavement is unobstructed and not bringing sediment or debris to the pavement. Underdrain not freely flowing Underdrain is not flowing when pavement has been infiltrating water. Underdrain flows freely when water is present. Overflow not controlling excess water Overflow not controlling excess water to desired location; native soil is exposed or other signs of erosion damage are present. Overflow permits excess water to leave the site at the desired location; Overflow is stabilized and appropriately armored. Permeable Pavers Broken or missing pavers Broken or missing paving blocks on surface of pavement. No missing or broken paving blocks interfering with infiltration. Uneven surface Uneven surface due to settlement or scour of fill in the interstices of the paving blocks. Pavement surface is uniformly level. Compaction Poor infiltration due to soil compaction between paving blocks. No soil compaction in the interstices of the paver blocks limiting infiltration. Poor vegetation growth (if applicable) Grass in the interstices of the paving blocks is dead. Healthy grass is growing in the interstices of the paver blocks. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 12/12/2016 2017 City of Renton Surface Water Design Manual A-42 NO. 31 – BIORETENTION BMP MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Preventive Vegetation Vegetation to be watered and pruned as needed and mulch applied to a minimum of 2 inches to maintain healthy growth. Healthy vegetation growth with full coverage as designed. Bioretention Area Trash and debris Trash and debris in the bioretention area; leaf drop in the fall season. No trash or debris In the bioretention area. Sediment accumulation Sediment accumulation in the bioretention area interfering with infiltration. Water in the bioretention infiltrates as designed. Excessive ponding Standing water in the bioretention area for more than two days. Standing water infiltrates at the desired rate. Inflow restricted Inflow not getting into bioretention; debris/sediment blockage at inlet features; native soil is exposed or other signs of erosion damage is present. Unobstructed and properly routed inflow into bioretention area; inlet is stabilized and appropriately armored. Overflow not controlling excess water Overflow water not controlled by outlet features; native soil is exposed or other signs of erosion damage is present. Outlet features control overflow; overflow is stabilized and appropriately armored. Underdrain not freely flowing Underdrain is not flowing when bioretention area has been infiltrating water. Underdrain flows freely when water is present. Vegetation Poor vegetation coverage Plants not thriving across at least 80% of the entire design vegetated area within the BMP; overly dense vegetation requiring pruning. Healthy water tolerant plants in bioretention area, plants thriving across at least 80% of the entire design vegetated area within the facility. Insufficient vegetation Plants not water tolerant species. Plants are water tolerant. Weeds present Weeds growing in bioretention area. No weeds in bioretention area. Watering not occurring Planting schedule requires frequent watering (approx. weekly Year 1, bimonthly Years 2 and 3) for new facilities, and as needed for established plantings or dry periods Plants are established and thriving Pest control Signs of pests, such as wilting or chewed leaves or bark, spotting or other indicators; extended ponding period encouraging mosquitoes Plant community is pest-free when following an approved Integrated Pest Management plan; bioretention functioning normally and ponding controlled as needed for pest control Containment Berm and Earthen Slopes Erosion Erosion occurring at earthen slopes or containment berm side slope. Erosion on the containment berm and side slopes has been repaired and the cause of the erosion corrected. Voids created by nuisance animals (e.g., rodents) or tree roots Voids affecting berm integrity or creating leaky pond condition Voids have been repaired; facility is free of nuisance animals following an approved Integrated Pest Management plan. Settlement Any part of the containment berm top has less than 6 inches of freeboard from the maximum pond level to the top of the berm. A minimum of 6 inches freeboard from the maximum pond level to the top of the berm. Amended Soil Poor soil nutrients Soil not providing plant nutrients. Soil providing plant nutrients. Bare spots Bare spots on soil in bioretention area. No bare spots, bioretention area covered with vegetation or mulch mixed into the underlying soil. Compaction Poor infiltration due to soil compaction in the bioretention area. No soil compaction in the bioretention area. An company 2 THE MOST ADVANCED NAME IN WATER MANAGEMENT SOLUTIONS TM ECCENTRICHEADER MANHOLEWITHOVERFLOWWEIR STORMTECHISOLATOR ROW OPTIONAL PRE-TREATMENT OPTIONAL ACCESS STORMTECH CHAMBERS )( Fire Station 15 Technical Information Report Submitted: November 10, 2017; Revised: February 12, 2018 APPENDIX E Declaration of Covenant DeclarationofCovenantshallrunwiththelandandbebindinguponGrantor(s),andGrantor’s(s’)successorsininterest,andassigns.9.ThisDeclarationofCovenantmaybeterminatedbyexecutionofawrittenagreementbytheOwnersandtheCitythatisrecordedbyKingCountyinitstealpropertyrecords,INWITNESSWHEREOF,thisDeclarationofCovenantfortheInspectionandMaintenanceofDrainageFacilitiesisexecutedthis3/dayof3A1iJl/‘1-2Af,2OtOR,wnerthePropertyGRANTOR,ownerofthePropertySTATEOFWASHINGTON)COUN’I’YOFKING)ss.Onthisdaypersonallyappearedbeforeme:Ke(t\.jI’(4W%J’Y’,tomeknowntobetheindividual(s)describedinandwhoexee6tedth&’withinandforegoinginstrumentandacknowledgedthattheysignedthesameastheirfreeandvoluntaryactanddeed,fortheusesandpurposesthereinstated.GivenundermyhandandofficialsealthisayofJU,2OI.c6fr7J-We1rnamePublicinandfortheStateofWashington,atMyappointmentexpiresPage3of3 exposedtotheweatherforthepurposeoflimitingmetalsinstoimwatertiowsandissubjecttothefollowingrcstrictions.TheGrantor(s)herebycovenants(covenant)andagiees(agree)asfollows:noleachablemetalsurfacescxposedtotheweatherwillbeallowedontheproperty.Leachablemetalsurfacesmeansasurfaceareathatconsistsoforiscoatedwithanon-ferrousmetalthatissolubleinwater.Commonleachablemetalsurfacesinclude,butarenotlimitedto,galvanizedsteelroofing,gutters,flashing,downspouts,guardrails,lightposts,andcopperroofing.CityofRentonoritsmunicipalsuccessorsshallhaveanonexciusiveperpetualaccesseasementonthePropertyinordertoingressandegressoverthePropertyforthesolepurposesofinspectingandmonitoringthatnoleachablemetalispresentontheProperty.Thiseasement/restrictionisbindingupontheGrantor(s),itsheirs,successors,andassignsunlessoruntilanewdrainageorsiteplatiisreviewedandapprovedbytheCityofRentonoritssuccessor. OH C> t1 (ID H0z 0z C’, C) -C)C) C’,C -C) -C)C) C)C) C)C) -IC) 0 C’, -IC) C)’C) <0 C C) C) C)C)-C) 2;:.C (‘C) C U)C’, _C)C) C) CC) C) 1i- C) —C) C)—.-.<. U) CC ‘‘ N. 0 > H 0 C C)C) C C)-C) -C) 0 zH0’ C C) f EXHIBIT A - DRAINAGE FACILITIES PAGE 1 Fire Station 15 Technical Information Report Submitted: November 10, 2017; Revised: February 12, 2018 APPENDIX F Downstream Analysis Photos Catch basin within N 30th St (Right) System conveys stormwater west Approximate ¼ mile downstream from site between Park Ave and Burnett Ave N (looking east along N 30th St) Catch basin at the intersection of N 30th St and Park Ave N (left) Catch basin within N 30th St (Right) System conveys stormwater west Approximate ¼ mile downstream from site between Park Ave and Burnett Ave N (looking west along N 30th St) Stormwater manhole within Burnett Ave N. System conveys stormwater west from this point (looking north in front of 3399 Burnett Ave N) Approximate discharge location to existing drainage system within Washington Blvd N. System convey stormwater west from this point (looking east in front of 3312 Lake Washington Blvd N) Approximate location of Lake Washington outfall (looking west on Lake Washington Blvd N) Fire Station 15 Technical Information Report Submitted: November 10, 2017; Revised: February 12, 2018 APPENDIX G Geotechnical Report and Supplemental Memorandum GEOTECHNICAL REPORT Elliott Bridge No. 3166 Replacement HWA Job No. 1996-143-21 Prepared for ABKJ, INC. April 4, 2003 GEOTECHNICAL REPORT Renton Fire Station 15 Renton, Washington HWA Project No. 2016-136-21 Prepared for SSW Architects, P.S. December 21, 2017 TABLE OF CONTENTS Page 1. INTRODUCTION ..........................................................................................................1 1.1 GENERAL .....................................................................................................1 1.2 PROJECT DESCRIPTION ................................................................................1 2. FIELD AND LABORATORY TESTING ...........................................................................2 2.1 GEOTECHNICAL SUBSURFACE EXPLORATIONS ............................................2 2.2 INFILTRATION TESTING PROGRAM ..............................................................3 2.3 LABORATORY TESTING ...............................................................................3 2.4 PREVIOUS EXPLORATIONS ...........................................................................3 3. SITE CONDITIONS ......................................................................................................4 3.1 GEOLOGIC CONDITIONS ..............................................................................4 3.2 SOIL CONDITIONS ........................................................................................4 3.3 GROUND WATER .........................................................................................5 4. CONCLUSIONS AND RECOMMENDATIONS ..................................................................5 4.1 GENERAL .....................................................................................................5 4.2 SEISMIC DESIGN CONSIDERATIONS .............................................................5 4.2.1 Seismic Design Parameters .............................................................5 4.2.2 Liquefaction ....................................................................................6 4.2.3 Ground Rupture ..............................................................................7 4.3 ESTIMATED SETTLEMENTS ..........................................................................7 4.4 FOUNDATION RECOMMENDATIONS .............................................................7 4.4.1 Slab-On-Grade Recommendations ...............................................8 4.5 RETAINING WALL .......................................................................................8 4.5.1 Wall Drainage .................................................................................9 4.5.2 General Wall Subgrade Preparation ................................................9 4.6 BELOW-GRADE STRUCTURES ......................................................................9 4.7 STORMWATER MANAGEMENT .....................................................................10 4.8 BIORETENTION POND CONSTRUCTION ........................................................10 4.9 PAVEMENT ..................................................................................................10 4.9.1 Placement of HMA ........................................................................11 4.9.2 HMA Drainage................................................................................12 4.9.3 Pervious Concrete Pavement Design ..............................................12 4.9.4 Pervious Portland Cement Concrete ...............................................13 4.9.5 Recharge Bed Design and Subgrade Preparation ...........................13 4.10 SITE EARTHWORK RECOMMENDATIONS ......................................................14 4.10.1 Structural Fill and Compaction .....................................................14 4.10.2 Excavation and Temporary Shoring .............................................15 4.10.3 Wet Weather Earthwork ...............................................................15 5. CONDITIONS AND LIMITATIONS......................................................................16 6. REFERENCES .........................................................................................................18 Table of Contents (Continued) Renton FS 15 - Revised Final Report 12212017 ii HWA GEOSCIENCES INC. LIST OF FIGURES (FOLLOWING TEXT) Figure 1. Vicinity Map Figure 2. Site and Exploration Plan Figure 3. Geologic Map Appendices Appendix A: Field Exploration Figure A-1. Legend to Symbols and Terms Used on Explorations Figures A-2 – A-4. Logs of Borings BH-4 through BH-6 Figure A-5. Log of Test Pit TP-2 Appendix B: Laboratory Testing Figures B-1 – B-7. Grain Size Distribution Test Results Appendix C: Additional Explorations GEOTECHNICAL REPORT RENTON FIRE STATION 15 RENTON, WASHINGTON 1. INTRODUCTION 1.1 GENERAL This report summarizes the results of geotechnical studies performed by HWA GeoSciences Inc. (HWA) for the proposed Renton Fire Station 15 project in Renton, Washington. The purpose of the work was to evaluate the soil and ground water conditions at the site and provide geotechnical recommendations for design and construction of the proposed facility. Our field work included drilling three (3) machine-drilled borings and conducting one (1) Pilot Infiltration Test (PIT) near the proposed fire station to evaluate soil and groundwater conditions. Laboratory tests were performed on selected soil samples to determine their relevant engineering properties. 1.2 PROJECT DESCRIPTION We understand that the City of Renton proposes to construct a fire station at 1404 N 30th Street in the Kennydale neighborhood of Renton, Washington. The addition of a new fire station will provide improved response times for fire and emergency services in the Kennydale neighborhood and the RRFA service area, relieving some of the current load placed on Fire Stations 11, 12 and 16. North of the project site, in the same parcel, the City proposes to construct a new reservoir as part of a separate project. The approximate location of the project site is shown on the Vicinity Map, Figure 1, and on the Site and Exploration Plan, Figure 2. The proposed fire station site is part of a city-owned rectangular parcel with a total existing parcel area of 47,532 SF (1.09 acres). The limits of work for the fire station project is within the southernmost subdivided lot totaling 31,173 SF (0.72 acres). We understand a reservoir is to be constructed on the northern third of the site and the fire station will be built on the southern two-thirds. HWA previously performed a geotechnical study for the proposed reservoir. The site is currently unimproved; and slopes gently upwards from the southwest to northeast, varying in elevation from approximately 208 feet to 226 feet. The fire station will be a single- story (measuring about 92 feet by 104 feet), at-grade structure with emergency vehicle equipment bays. December 21, 2017 HWA Project No. 2016-136-21 Renton FS 15 - Revised Final Report 12212017 2 HWA GEOSCIENCES INC. We understand that onsite infiltration is the preferred method of storm water management for this site. On-site stormwater management will be implemented via a bioretention pond and the permeable pavement facility. Additional site improvements are expected to include a below- grade storm water detention vault. An approximately 3-foot tall retaining wall is to be constructed east of the fire station building accommodate grade changes. 2. FIELD AND LABORATORY TESTING 2.1 GEOTECHNICAL SUBSURFACE EXPLORATIONS In support of design of the proposed Renton Fire Station 15 project, HWA drilled three (3) exploratory borings, designated BH-4 through BH-6, in sequence with borings drilled for the reservoir project to the north. The locations of these borings are shown on Figure 2. The borings were drilled by Environmental Drilling Inc. (EDI) of Snohomish, Washington, under subcontract to HWA. The drilling was performed using a B-61 Mobile truck rig equipped with a 4.25-inch inside-diameter hollow-stem auger and an automatic hydraulic hammer. In each boring, Standard Penetration Test (SPT) sampling was performed at selected intervals and the SPT resistance (“N-value”) of the soil was logged. This resistance, or N-value, provides an indication of relative density of granular soils and the relative consistency of cohesive soils. Boring BH-4 was positioned near the center of the proposed fire station. It was drilled to a depth of 31.5 feet below ground surface. Boring BH-5 was drilled to a depth of 44 feet below ground surface near the proposed below grade storm water vault. Boring BH-6 was drilled to a depth 31.5 feet below ground surface north of the proposed fire station location. In each boring, Standard Penetration Test (SPT) sampling was performed at selected intervals and the SPT resistance (“N-value”) of the soil was logged. This resistance, or N-value, provides an indication of relative density of granular soils and the relative consistency of cohesive soils. A geologist from HWA logged the explorations and recorded pertinent information, including sample depths, stratigraphy, soil engineering characteristics, and ground water occurrence. Soil samples obtained from the exploration were classified in the field and representative portions were placed in plastic bags. These soil samples were taken to our Bothell, Washington, laboratory for further examination and testing. Logs for borings BH-4 through BH-6 are presented in Appendix A of this report. The stratigraphic contacts shown on the exploration logs represent the approximate boundaries between soil types; actual transitions may be more gradual. The soil and ground water December 21, 2017 HWA Project No. 2016-136-21 Renton FS 15 - Revised Final Report 12212017 3 HWA GEOSCIENCES INC. conditions depicted are only for the specific date and location reported and, therefore, are not necessarily representative of other locations and times. 2.2 INFILTRATION TESTING PROGRAM Phase 2 of our exploration program consisted of conducting one (1) Pilot Infiltration Test (PIT), designated PT-2, in sequence with the PIT conducted for the reservoir project. The excavation for the PIT was conducted on July 24 and 25, 2017 by Kelly’s Excavating Inc. of Pacific, Washington, under subcontract to HWA. The PIT was dug 7 feet into the ground to remove surficial topsoil and upper layers of silt and silty sands. Slightly cleaner sands were encountered at 7 feet below the ground surface where the test was performed. The dimensions of the test pit inside of the excavation area were 3.5 feet by 5 feet. Following the PIT, PT-2 was excavated to a depth of 13 feet to evaluate soils and ground water conditions below the test. The test consisted of introducing water at a known flow rate into the excavation. Water was obtained from a nearby water service in cooperation with the City of Renton Utility Division and pumped into the excavation using a water trailer provided by Kelly’s Excavating, Inc. Slotted pipe terminating in a 5-gallon bucket was used to dissipate the water into the excavation. Water levels were measured with a staff gauge installed in the excavation along with a Levelogger Edge water level datalogger. At selected intervals, HWA recorded total flow through a meter and calculated the flow rate. The flow rate was adjusted to establish and maintain a water level of approximately 1 foot above the base of the PIT. After approximately 7 hours of flow, the water was turned off. Water levels in the excavation were monitored until all the water had drained out of the test pit. An HWA geologist logged the exploration and recorded all the pertinent information including sample depths, stratigraphy, soil engineering characteristics, and ground water occurrence at the time of excavation. More information regarding the PIT procedure is presented in Section 4.7 of this report. 2.3 LABORATORY TESTING Laboratory tests included determination of natural moisture contents and grain size distributions. All testing was conducted in general accordance with appropriate American Society for Testing and Materials (ASTM) standards, as discussed in Appendix B. The test results and a discussion of laboratory test methodology are presented in Appendix B, or displayed on the boring logs in Appendix A, as appropriate. 2.4 PREVIOUS EXPLORATIONS Geotechnical explorations, performed for the Kennydale 320 Pressure Zone Reservoir by HWA in 2015, were reviewed and utilized in this study. Three borings and one PIT test were December 21, 2017 HWA Project No. 2016-136-21 Renton FS 15 - Revised Final Report 12212017 4 HWA GEOSCIENCES INC. performed as part of this project. The locations of these borings are shown on Figure 2. Copies of these boring logs are provided in Appendix C. 3. SITE CONDITIONS 3.1 GEOLOGIC CONDITIONS General geologic information for the project area was obtained from the Geologic Map of King County (Booth et. al., 2006). A portion of this geologic map is shown in Figure 3 of this report. The map indicates the project vicinity is underlain by deposits of the Fraser glaciation described as Vashon recessional outwash. Recessional outwash deposits consist of material washed out of a melting glacier and are characterized by stratified sand and gravel. These soils are moderately to well sorted, with less common silty sand and rare silty clay. These materials have not been glacially overridden and are typically loose to medium dense. 3.2 SOIL CONDITIONS Our interpretations of subsurface conditions are based on results of our field explorations, review of available geologic and geotechnical data, and our experience in similar geologic settings. In general, the soils underlying the site consist of loose to medium dense, recessional outwash sands over medium dense to dense weathered till. Each major soil unit is described below, with materials interpreted as being youngest in origin and nearest to the surface described first. • Recessional Outwash: Recessional outwash consisting of loose to medium dense, olive brown, clean to silty sand to sandy silt, was encountered in all the explorations. Borings BH-4 and BH-6 and test pit TP-2 were terminated within the recessional outwash soils. Recessional outwash was deposited by meltwater emanating from the retreating glacial ice sheet. Consequently, it has not been overridden by glacial ice and is typically loose to medium dense. The upper 5 to 7 feet of recessional outwash typically consisted of loose to medium dense, sandy silt. It should be noted that a large boulder was partially exposed in TP-2 about 5 feet bgs. • Weathered Till: Weathered till was encountered in boring BH-5 below the recessional outwash sands at 37 feet bgs. This unit consisted of very stiff sandy silt and medium dense to dense, silty, gravelly sand. Previous explorations at the site to the north encountered glacial till below the recessional outwash deposits, as indicated in the logs of borings BH-1 and BH-2, which are presented in Appendix C. Although not encountered in our borings, cobbles and boulders are known to exist in glacial deposits. December 21, 2017 HWA Project No. 2016-136-21 Renton FS 15 - Revised Final Report 12212017 5 HWA GEOSCIENCES INC. 3.3 GROUND WATER At the time of our field investigation, perched ground water seepage was observed only in boring BH-5 at a depth 32.5 feet below ground surface. The ground water seepage observed may not necessarily be indicative of other times and/or locations and it is anticipated that ground water conditions will vary depending on the weather, local subsurface conditions, and other factors. 4. CONCLUSIONS AND RECOMMENDATIONS 4.1 GENERAL The proposed fire station site is underlain by recessional outwash over weathered till soils. The recessional outwash will provide suitable bearing for the proposed structure. The loose to medium dense, recessional outwash sands will experience elastic settlement due to the increases in load associated with the proposed structure. However, most of this settlement will occur during construction. We recommend the structure be designed and constructed with spread footing foundations bearing on a layer of compacted structural fill placed over the native soils. Because the upper 5 to 7 feet of outwash soils are relatively loose, we recommend they be compacted prior to construction of foundations. We recommend that the building site be excavated to the proposed floor subgrade level and then compacted by at least 4 complete coverages with a 10-ton (minimum static weight) vibratory roller. In addition, individual footing subgrades should be compacted with a backhoe-mounted vibratory plate compactor (hoepac). On-site stormwater management will be implemented via a bioretention pond and the permeable pavement facility. It should be noted that sandy silt soils with high percentage of fines were encountered from the ground surface to 5-7 feet below ground surface. These soils are not conducive to infiltration. Therefore, we recommend over-excavating the upper fine-grained material (sandy silt soils) and backfilling with permeable ballast, per WSDOT Standard Specification 9-03.9(2). The granular material placed underneath the bioretention pond and pervious pavement should be compacted lightly. Recommendations related to site seismicity, foundations, retaining walls, utilities, below-grade structures, stormwater management, earthwork, and pavement are presented in the following sections. 4.2 SEISMIC DESIGN CONSIDERATIONS 4.2.1 Seismic Design Parameters Earthquake loading for the structures at the project site was developed in accordance with the 2015 International Building Code (IBC), (ICC, 2015). The IBC requires above-grade structures December 21, 2017 HWA Project No. 2016-136-21 Renton FS 15 - Revised Final Report 12212017 6 HWA GEOSCIENCES INC. be designed for the inertial forces induced by a “Maximum Considered Earthquake” (MCE), which corresponds to an earthquake with a 2% probability of exceedance (PE) in 50 years (approximately 2,475-year return period). Accordingly, the relevant probabilistic spectral response parameters were developed using the United States Geological Survey’s website. The IBC accounts for the effects of site-specific subsurface ground conditions on the response of structures in terms of site classes. Site classes are defined by the average density and stiffness of the soil profile underlying the site. The Site Class can be correlated to the average standard penetration resistance (NSPT) in the upper 100 feet of the soil profile. Based on our characterization of the subsurface conditions, the subject site classifies as IBC Site Class D. Table 1 presents the design spectral seismic coefficients obtained for this site based on risk category I/II/III. The design peak ground acceleration for use in computing lateral earth pressures was computed to be 0.385 g. Based on the SDS and SD1 values, the site is considered as Seismic Design Category D. Table 1. Design Seismic Coefficients for IBC 2015 Code Based Evaluation Site Class Spectral Acceleration at 0.2 sec. SS(1), g Spectral Acceleration at 1.0 sec S1(2), g Design Spectral Acceleration at 0.2 sec. SDS(3), g Design Spectral Acceleration at 1.0 sec. SD1(4), g Site Coefficients Peak Horizontal Acceleration PGA, (g) Fa(5) Fv(6) D 1.444 0.546 0.963 0.546 1.000 1.500 0.385 (1) SS = Mapped spectral response acceleration parameter at short periods (at a period of 0.2 sec) (2) S1 = Mapped spectral response acceleration parameter at a period of one second (3) SDS = Design spectral response acceleration parameter at short periods (at a period of 0.2 sec) (4) SD1 = Design spectral response acceleration parameter at a period of one second (5) Fa = short period site coefficient (at a period of 0.2 sec) (6) Fv = long period site coefficient (at a period of one second) The project site is located within about 2 miles of the Seattle Fault Zone. The main seismic consideration for the site is the large amplitude of the ground motions associated with its proximity to the fault, which is accounted for in the design seismic coefficients. With respect to the design parameters for the vertical accelerations, the recommendations provided in the ASCE 7-10 Section 12.4.2.2 (ASCE, 2010) should be applied. 4.2.2 Liquefaction Primary factors controlling the development of liquefaction include the intensity and duration of strong ground motions, the characteristics of subsurface soils, in-situ stress conditions and the depth to ground water. Based on the ground water elevations observed in our explorations, the December 21, 2017 HWA Project No. 2016-136-21 Renton FS 15 - Revised Final Report 12212017 7 HWA GEOSCIENCES INC. materials that are saturated are dense to very dense and will not be subject to liquefaction during shaking. Therefore, liquefaction is not a design consideration for this project. 4.2.3 Ground Rupture A review of the existing geologic data indicates that there are no known active faults at this site; therefore, ground rupture is not a design consideration. 4.3 ESTIMATED SETTLEMENTS The soils underlying the fire station site consist of recessional outwash sands over weathered glacial till. Assuming the recommendations in this report are followed, we anticipate that settlements under static loads will be no more than ½ inch. Most of this settlement will occur during construction as the loads are applied. Settlement under the design seismic load could total an additional ¼ inch. 4.4 FOUNDATION RECOMMENDATIONS The proposed fire station and retaining wall should be supported on spread footings or mat foundations designed for a maximum allowable bearing pressure of 3,000 pounds per square foot. For short-term wind and seismic loading conditions, the allowable bearing pressure may be increased by 1/3. Footings should have a minimum width of 24 inches and should bear at least 18 inches below the lowest adjacent finished grade. Individual footing subgrades should be compacted with a hoepac prior to placement of formwork, steel, or concrete. The footings should be supported on a minimum of 1-foot of structural fill placed directly over the compacted native soils. Where needed, structural fill should consist of Crushed Surfacing Top Course (CSTC) as specified in Section 9-03.9(3) of the WSDOT Standard Specifications (WSDOT, 2016). Any soft or disturbed soils and any soil containing organic material (unsuitable material) should be removed under the observation of an HWA engineer or geo-technician to verify competent native soils are exposed. Wind and seismic transient lateral forces on the structure will be resisted by friction along the footings, and by passive soil pressure against the buried portions of the footings. An ultimate coefficient of friction of 0.5 may be assumed for cast-in-place concrete on granular material. Also, a passive resistance to lateral loads maybe estimated as an equivalent fluid pressure of 250 pcf. These are ultimate resistance values, and an adequate factor of safety should be applied in design calculations. Perimeter footing drains should be installed around the entire building exterior. The perimeter footing drains should consist of 4-inch diameter, perforated or slotted, rigid plastic pipes, bedded and backfilled with Gravel Backfill for Drains, as specified in Section 9-03.12(4) of the 2016 WSDOT Standard Specifications. Footing drain inverts should be at least 12 inches lower than the bottom of floor slabs. Footing drains should be sloped to drain into an appropriate outlet, December 21, 2017 HWA Project No. 2016-136-21 Renton FS 15 - Revised Final Report 12212017 8 HWA GEOSCIENCES INC. such that storm water cannot backup around the footings. Roof drains should not be tied into the perimeter drain system to prevent potential backup into the perimeter drains during intense storm events. The ground surface should be graded to direct surface water away from the structures. 4.4.1 Slab-On-Grade Recommendations The slab-on-grade should be supported on a minimum of 1-foot of structural fill placed directly over the compacted native soils. Structural fill should consist of Crushed Surfacing Top Course (CSTC). Any soft or disturbed soils and any soil containing organic material (unsuitable material) should be removed under the observation of an HWA engineer or geo-technician to verify competent native soils are exposed. Because the ground surface slopes down to the west, the structural fill thickness will likely vary across the slab footprint. If the fill material is poor or if compaction is inadequate, the variable structural fill thickness could lead to differential settlement in the fill, resulting in the formation of cracks greater than the tolerable limits for the serviceability of the apparatus bay floor. The recommended structural fill should be compacted to at least 95% of its maximum dry density, based on the Modified Proctor Test. Slab-on-grade floors should be underlain by a capillary break layer consisting of at least 6 inches of washed 3/8-inch pea gravel. A 10-mil (minimum thickness) plastic vapor barrier should be placed over this capillary break layer. Joints in the vapor barrier should overlap at least 2 feet or be sealed with adhesive or double-sided tape in accordance with the manufacturer’s recommendations. A 2-inch thick layer of concrete sand may be placed over the vapor barrier to protect the vapor barrier and to provide for more uniform concrete curing. Placement of the vapor barrier should be undertaken with care, and construction activity on the membrane should be limited after placement to avoid perforations in the membrane. 4.5 RETAINING WALL It is our understanding that a 3-foot tall, cast-in-place retaining wall will be required at the east side of the fire station property to accommodate changes in grade. The location of the wall is shown on the Site and Exploration Plan, Figure 2. Wall design should provide resistance for the lateral earth pressures from the retained soil. For wall design, the at-rest lateral earth pressure for design of the wall should be 57 pounds per cubic foot (pcf). This earth pressure assumes that the wall is backfilled with well compacted structural fill. This assumes that no ground water pressures develop behind the wall, which is appropriate assuming adequate drainage measures are provided. We recommend the Contractor be required to submit the proposed wall design for approval by the Engineer. December 21, 2017 HWA Project No. 2016-136-21 Renton FS 15 - Revised Final Report 12212017 9 HWA GEOSCIENCES INC. 4.5.1 Wall Drainage Drainage should be provided to prevent the buildup of hydrostatic pressures behind all retaining walls. Drainage should consist of a perforated drain pipe along the base of the wall, embedded in Gravel Backfill for Drains, per WSDOT Standard Specification Section 9-03.12(4) (WSDOT, 2016). The drain pipe should be graded to direct water from the backfill and subgrade soils to a suitable outlet. 4.5.2 General Wall Subgrade Preparation Subgrade preparation is important to limit differential settlement of the wall and maintain global stability. All organic material should be removed. Loose or soft soils, defined as being penetrable more than 1 foot with a 1/2-inch diameter rod pushed in under a 150 lb load (T-probe pushed in by hand), should be removed and replaced with structural backfill or be suitably compacted. The area on which the wall will rest should be graded level perpendicular to the wall face and compacted in accordance with WSDOT Standard Specifications Section 2-03.3(14)D (WSDOT, 2016). It should be noted that 5 to 7 feet of loose/soft silt material was encountered in our explorations. This material is not suitable for wall base. Therefore, we recommend the wall be founded on a 1-foot thick leveling pad constructed of compacted Crushed Surfacing Top Course (CSTC) placed over compacted native soils. Fill against an existing slope will require terraced cuts as outlined in WSDOT Standard Specifications Section 2-03.3(14), Embankment Construction (WSDOT, 2016). 4.6 BELOW-GRADE STRUCTURES All below grade structures should be designed with consideration of the anticipated lateral earth pressures that will be applied on the structures. We expect that these buried structures will not be free to yield and will develop at-rest earth pressures upon backfilling. These structures should be designed to resist an equivalent fluid pressure of at least 60 pounds per cubic foot (pcf). This earth pressure assumes no accumulation of water behind the wall. Proper drainage should be provided to ensure that hydrostatic pressures do not develop behind these structures. Where drainage is not provided, the structure should be designed for an allowable equivalent fluid pressure of 120 pcf. Under earthquake loading conditions, the buried structures will experience an incremental additional horizontal earth pressure. This increment can be approximated using the Mononobe- Okabe method utilizing 0.5 times the PGA for the site, (0.5)(0.385g) = 0.19g. This results in a design active-plus-seismic earth pressure coefficient, Kae = 0.37. For design purposes, a design active-plus-seismic equivalent fluid pressure of 52 pcf would be slightly less than the recommended at-rest pressure of 60 pcf. December 21, 2017 HWA Project No. 2016-136-21 Renton FS 15 - Revised Final Report 12212017 10 HWA GEOSCIENCES INC. 4.7 STORMWATER MANAGEMENT It is our understanding that the City would like to utilize onsite infiltration as a means of stormwater management for the project. On-site stormwater management will be implemented via a bioretention pond and permeable pavement. Pilot Infiltration Testing (PIT) was performed in general accordance with the King County, Washington, Surface Water Design Manual (King County, 2016). HWA conducted a PIT at a depth of 7 feet bgs in the vicinity of the proposed bioretention pond, north of borehole BH-5 on the northeast corner of the proposed fire station. The bottom of the PIT was at approximately 7 feet below existing ground surface. Ground water was measured in the nearby borehole piezometer BH-1 at 46.6 in November 2016. Therefore, the depth to ground water below the proposed pond bottom readily exceeds the minimum 3-foot vertical separation requirement. Also, the minimum requirement of 3 feet of permeable soil beneath the infiltration facility was confirmed by digging 6 feet deep through the PIT test surface to a total depth of 13 feet after the test. No perching water was observed when test pitting through the bottom of the PIT. Discharge into the excavation stabilized approximately 1 hours into the test, at a flow rate of 1.25 gallons per minute (gpm). Based on the test results, we recommend a long-term infiltration rate of 1.1 in/hr, assuming the removal of the upper 7 feet of soil (silty material). 4.8 BIORETENTION POND CONSTRUCTION The project proposes a 20-feet long by 18-feet wide bioretention pond, with a total designed volume of 122 cubic feet. The bioretention area consists of 18-inches of bioretention soil mix underlain by 18-inches of drain rock over the native subgrade. However, sandy silt soils with high percentage of fines were encountered near the ground surface (about 5-7 feet below ground surface). These soils are not conducive to infiltration. Therefore, we recommend over- excavating the fine-grained material (sandy silt soils) and backfilling with permeable ballast, per WSDOT Standard Specification 9-03.9(2). The granular material placed underneath the bioretention pond should be compacted lightly while keeping compaction equipment movement over the bioretention pond subgrade to a minimum. 4.9 PAVEMENT It is our understanding that a 16 to 24 feet wide access road will be designed and constructed to provide access to maintenance vehicles as shown on the Site and Exploration Plan, Figure 2. This access road will consist of a combination of Hot Mix Asphalt (HMA) and pervious concrete. We understand that this road will be used primarily by service vehicles and not by December 21, 2017 HWA Project No. 2016-136-21 Renton FS 15 - Revised Final Report 12212017 11 HWA GEOSCIENCES INC. heavy equipment or heavy trucks. Therefore, for the HMA portion, we recommend a new pavement section consisting of 4 inches of HMA over 6 inches of compacted Crushed Surfacing Base Course (CSBC), as shown in Table 2. Table 2. Structure Requirements for New HMA Pavement Material Description Minimum Layer Thickness (inches) WSDOT Standard Specification HMA 4 5-04 CSBC 6 9-03.9(3) Structural Fill/Prepared Subgrade Proof-roll 9-03.14(1) The pavement layer thicknesses given in Table 2 do not account for heavy construction traffic. If a significant volume of construction traffic (mainly fully-loaded trucks) will operate over the completed base before placement of the surfacing, or if the moisture content of the subgrade is elevated as result of rainfall, then heaving and rutting could occur. In such cases, the thickness of base, or structural fill, should be increased. One to two feet of structural fill/quarry spalls may be required below the CSBC to provide a base for the compacted materials above. We recommend that the asphalt layers consist of HMA Class ½-inch. The maximum lift thickness for HMA Class ½-inch is 0.3 feet (or 3.6 inches), as stipulated by WSDOT (WSDOT, 2016). 4.9.1 Placement of HMA Placement of HMA should be in accordance with Section 5-04 of the WSDOT Standard Specifications (WSDOT, 2016). Particular attention should be paid to the following: HMA should not be placed until the engineer has accepted the previously constructed pavement layers. HMA should not be placed on any frozen or wet surface. HMA should not be placed when precipitation is anticipated before the pavement can be compacted, or before any other weather conditions which could prevent proper handling and compaction of HMA. HMA should not be placed when the average surface temperatures are less than 45o F. HMA temperature behind the paver should be in excess of 240o F. Compaction should be completed before the mix temperature drops below 180o F. Comprehensive temperature records should be kept during the HMA placement. December 21, 2017 HWA Project No. 2016-136-21 Renton FS 15 - Revised Final Report 12212017 12 HWA GEOSCIENCES INC. For cold joints, tack coat should be applied to the edge to be joined and the paver screed should be set to overlap the first mat by 1 to 2 inches. 4.9.2 HMA Drainage It is essential to the satisfactory performance of the roadway that good drainage is provided to prevent water ponding alongside the pavement causing saturation of the pavement and subgrade layers. The base layers should be graded to prevent water being trapped within the layer. The surface of the pavement should be sloped to convey water from the pavement to appropriate drainage facilities. 4.9.3 Pervious Concrete Pavement Design It is our understanding that a section of the access road and the parking area located north of the fire station will consist of pervious concrete pavement. It should be noted that sandy silt soils with high percentage of fines were encountered near the ground surface (about 5-7 feet below ground surface). These soils are not conducive to infiltration. Therefore, we recommend over- excavating the upper fine-grained material (sandy silt soils) to expose the clean native soils and backfilling with permeable ballast, per WSDOT Standard Specification 9-03.9(2) (WSDOT, 2016). The granular material placed underneath the pervious pavement should be compacted to a dense and unyielding condition while keeping compaction equipment movement over the subgrade to a minimum. In general, pervious pavement sections consist of a wearing course, a choker course, a recharge bed course, and a carefully prepared subgrade. Regardless of the type of the wearing course used, the size and composition of the remaining courses are generally the same. Table 3 presents our recommendations for the pervious concrete pavement section. The following sections provide our recommendations for each component of the pervious pavement section. December 21, 2017 HWA Project No. 2016-136-21 Renton FS 15 - Revised Final Report 12212017 13 HWA GEOSCIENCES INC. Table 3. Structure Requirements for New Pervious PCC Pavement Material Description Minimum Layer Thickness (inches) WSDOT Standard Specification PCC Wearing Surface 6 5-05 Choker Course (AASHTO No. 57) 1 - Recharge Bed (AASHTO No. 2) Varies (18-36) Section 5.05.2 Non-Woven Geosynthetic - 9-33.2(1) Prepared Subgrade Uncompacted Section 5.05.3 4.9.4 Pervious Portland Cement Concrete Based on the anticipated light loading conditions and the nature of pervious concrete pavement, it is our recommendation that this pavement section consist of a minimum of 6 inches of pervious Portland cement concrete pavement. Pervious Portland cement concrete is typically a proprietary product that is available from many local concrete batch plants. In general, the pervious concrete mix uses uniformly graded crushed coarse aggregate (e.g. meeting AASHTO grading No. 8) with no, or limited use of, fine aggregate and a water/cement ratio ranging from 0.27 to 0.35. The 28-day compressive strength of the mix is typically between 2,500 psi and 4,000 psi with an average modulus of rupture of about 350 to 375 psi. The unit weight of the mix is between 100 and 125 pcf with a porosity of 15% to 25%. The initial permeability of the hardened product is between 300 and 800 in/hr. We recommend that expansion joints be saw cut into the concrete at spacings of no greater than 12 feet to limit post construction cracking. These joints need not be sealed. Maintenance practices for cleaning pervious concrete should be implemented to maintain permeability. Some cleaning techniques are pressure washing, vacuum sweeping and/or a combination of these two methods. 4.9.5 Recharge Bed Design and Subgrade Preparation Recharge beds under pervious pavements should be adequately sized to provide sufficient storage during the 2-year design storm, and should also include an overflow system (or under- drain system) to handle peaks of more intense (25 or 50-year) storms. Typical bed thicknesses range between 1.5 feet and 3 feet. December 21, 2017 HWA Project No. 2016-136-21 Renton FS 15 - Revised Final Report 12212017 14 HWA GEOSCIENCES INC. The drain aggregate in the recharge bed should consist of 1 inch to 1.5 inch crushed, washed drain rock, or 1.5 to 2.5 inch washed crushed base aggregate such as AASHTO No. 2. The coarse gravel should be placed in 8-inch thick (maximum) loose lifts with each layer compacted to a dense and unyielding condition while keeping compaction equipment movement over recharge bed subgrade to a minimum. A design value of 0.3 should be used for the porosity of the base aggregate. A 1-inch thick choker course consisting of uniformly graded gravel, such as size AASHTO No.57 aggregate, should be placed over the surface of the recharge bed to provide a platform for the porous wearing surface. A nonwoven geotextile meeting the material requirements of WSDOT Standard Specifications (WSDOT, 2016) Section 9-33.1, with the properties listed in Section 9-33.2(1) Table 3 for Separation, should be placed along the sides of the excavation between the native and the drain aggregate to prevent migration of fines into the recharge bed. The nonwoven geotextile should not be placed below the pervious wearing surface over the top of the recharge bed aggregate. Placing nonwoven geotextile below the pervious wearing surface could result in clogging of the geotextile over time, reducing the functionality of the system. 4.10 SITE EARTHWORK RECOMMENDATIONS 4.10.1 Structural Fill and Compaction All fill placed at this site should be considered structural fill. Structural fill materials should consist of clean, free-draining granular soils, which are free of organic matter or other deleterious materials. The native soils along the project alignment are not suitable for reuse as structural fill for this project. Structural fill materials should be less than 4 inches in maximum particle dimension, with less than 7 percent fines (portion passing the U. S. Standard No. 200 sieve), as specified for Gravel Borrow in Section 9-03.14(1) of the WSDOT Standard Specifications (WSDOT, 2016) or Crushed Surfacing Top Course (CSTC) as specified in Section 9-03.9(3) of the WSDOT Standard Specifications (WSDOT, 2016). The fine-grained portion of structural fill soils should be non-plastic. All fill, except for fill required underneath the pervious concrete and bioretention pond, should be placed in lifts and compacted to at least 95 percent of the maximum dry density, as determined using test method ASTM D 1557 (Modified Proctor). The thickness of loose lifts should not exceed 8 inches for heavy weight compactors and 4 inches for hand-operated equipment. The procedure to achieve the specified minimum relative compaction depends on the size and type of compacting equipment, the number of passes, thickness of the layer being compacted, and certain soil properties. We recommend that the appropriate lift thickness, and the adequacy December 21, 2017 HWA Project No. 2016-136-21 Renton FS 15 - Revised Final Report 12212017 15 HWA GEOSCIENCES INC. of the subgrade preparation and materials compaction be evaluated by a representative of the geotechnical engineer during construction. A sufficient number of in-place density tests should be performed as the fill is being placed to verify that the required compaction is achieved. 4.10.2 Excavation and Temporary Shoring Excavations for the new foundations and below grade structures can be accomplished with conventional excavating equipment such as backhoes. We recommend that foundation excavation be accomplished with a smooth (toothless) bucket to minimize disturbance of subgrade soils. Any loosened or disturbed soils should be removed. It is our understanding that the proposed storm water facility is to extend approximately 9 feet below existing grade. Sloped excavations and/or standard trench box shoring may be used as means of temporary shoring. The maintenance of safe working conditions, including temporary excavation stability, is the responsibility of the contractor. In accordance with Part N of Washington Administrative Code (WAC) 296-155, latest revisions, all temporary cuts in excess of 4 feet in height must be either sloped or shored prior to entry by personnel. The existing granular soils on site are generally classified as Type C soils, per WAC 296-155. Where shoring is not used, temporary cuts in Type C soils should be sloped no steeper than 1½H:1V (horizontal: vertical). It is important that the contractor monitors the stability of temporary cut slopes and adjusts the construction schedule and slope inclination accordingly. 4.10.3 Wet Weather Earthwork During period of wet weather, even the most permeable soils can become difficult to work and compact. Given that the near surface soils across most of the site consist of recessional outwash sand, we expect variability in the fines content of these native soils. Soils with higher fines contents will be hard to compact when above a given moisture content (generally about 10 to 12 percent moisture). As a result, the moisture content of these soils may be difficult to control during periods of wet weather. If fill is to be placed or earthwork is to be performed in wet weather or under wet conditions, the following recommendations apply: • Earthwork should be accomplished in small sections to minimize exposure to wet weather. Excavation or the removal of unsuitable soil should be followed promptly by the placement and compaction of a suitable thickness of clean structural fill or lean concrete. The size and type of construction equipment used may need to be limited to prevent soil disturbance; • Material used as structural fill should consist of clean, granular soil, of which not more than 5 percent by dry weight passes the U.S. Standard No. 200 sieve, based on December 21, 2017 HWA Project No. 2016-136-21 Renton FS 15 - Revised Final Report 12212017 16 HWA GEOSCIENCES INC. wet sieving the fraction passing the ¾-inch sieve; this is an additional restriction for the structural fill materials described in Section 4.10.1. The fine-grained portion of the structural fill soils should be non-plastic; • The ground surface within the construction area should be sloped and sealed with a smooth drum vibratory roller to promote rapid runoff of precipitation and to prevent ponding of water; • No soil should be left uncompacted so it can absorb water. Soils which become too wet for compaction should be removed and replaced with clean granular materials; and • Excavation and placement of fill should be observed on a full-time basis by a person experienced in wet weather earthwork to verify that all unsuitable materials are removed and suitable compaction and site drainage are achieved. The above recommendations for wet weather earthwork should be incorporated into the contract specifications. 5. CONDITIONS AND LIMITATIONS We have prepared this report for the City of Renton and SSW Architects, P.S., for use in design phase of this project. This report should be provided in its entirety to prospective contractors for bidding and estimating purposes; however, the conclusions and interpretations presented herein should not be construed as a warranty of the subsurface conditions. Experience has shown that soil and groundwater conditions can vary significantly over small distances. Inconsistent conditions can occur between explorations that may not be detected by a geotechnical study. If, during future site operations, subsurface conditions are encountered which vary appreciably from those described herein, HWA should be notified for review of the recommendations of this report, and revision of such if necessary. If there is a substantial lapse of time between submission of this report and the start of construction, or if conditions change due to construction operations at or adjacent to the project site, it is recommended that this report be reviewed to determine the applicability of the conclusions and recommendations considering the changed conditions and time lapse. This report is issued with the understanding that it is the responsibility of the owner, or the owners’ representative, to ensure that the information and recommendations contained herein are brought to the attention of the appropriate design team personnel and incorporated into the project plans and specifications, and the necessary steps are taken to see that the contractor and subcontractors carry out such recommendations in the field. HWA is available to monitor construction to evaluate soil and groundwater conditions as they are exposed and verify that December 21, 2017 HWA Project No. 2016-136-21 Renton FS 15 - Revised Final Report 12212017 18 HWA GEOSCIENCES INC. 6.REFERENCES American Association of State Highway and Transportation Officials (AASHTO), 1993, AASHTO Guide for Design of Pavement Structures, American Association of State Highway and Transportation Officials. Booth, D.B. and Wisher, A.P. 2006. Geologic Map of King County 1:100,000 Quadrangles, Washington, Department of Earth and Space Sciences, University of Washington, GeoMapNW. International Code Council, 2015. International Building Code, 2015, published May, 2014, International Code Council, Falls Church, VA. King County Department of Natural Resources and Parks, April 2016. King County, Washington Surface Water Design Manual. Tokimatsu, K. and H.B. Seed, 1987. Evaluation of settlements in sands due to earthquake shaking, J. Geot. Engrg., 113 (8), 861-878. USGS Earthquake Hazards Program, 2002. “2002 Interactive Deaggregation”, USGS Earthquake Hazards Program, National Earthquake Hazard Maps, http://eqint.cr.usgs.gov/eq-men/html/deaggint2002. WSDOT, 2015 Geotechnical Design Manual, M 46-03.11. WSDOT, 2016. Standard Specifications for Road, Bridge and Municipal Construction, Washington State Department of Transportation. VICINITY MAP RENTON FIRE STATION 15 RENTON, WASHINGTON 1 2016-136-21 FIGURE NO. PROJECT NO. MAP NOT TO SCALE BASE MAP FROM GOOGLE MAPS DATA © 2016 GOOGLE N © 2016 Microsoft MDA Geospatial Services Inc. Lake Washington Approximate Extent of Project Site BH-1 Boring designation and approximate location. (HWA 2015) SITE AND EXPLORATION PLAN BH-4 BH-2 BH-3 BH-5 FIGURE NO. PROJECT NO. BH-1 RENTON FIRE STATION #15 RENTON, WASHINGTON 2 2016-136-21 Proposed Location of Bioretention Pond Boring designation and approximate location. (HWA 2017) BH-4 NOT TO SCALE Pilot Infiltration Test designation and approximate location. (HWA 2017) PT-2 PT-2 PT-1 BH-6 Area of Pervoius Pavement with infiltration . GEOLOGIC MAP RENTON FIRE STATION 15 RENTON, WASHINGTON 3 2016-136-21 FIGURE NO. PROJECT NO. MAP NOT TO SCALE N Approximate project site location APPENDIX A FIELD EXPLORATION A-12016-136-21 Renton Fire Statioin 15 Renton, Washington SYMBOLS USED ON EXPLORATION LOGS LEGEND OF TERMS AND to 30 over 30 Approximate Undrained Shear Strength (psf) <250 250 - No. 4 Sieve Sand with Fines (appreciable amount of fines) amount of fines) More than 50% Retained on No. 200 Sieve Size Sand and Sandy Soils Clean Gravel (little or no fines) More than 50% of Coarse Fraction Retained on No. 4 Sieve Gravel with SM SC ML MH CH OH RELATIVE DENSITY OR CONSISTENCY VERSUS SPT N-VALUE Very Loose Loose Medium Dense Very Dense Dense N (blows/ft) 0 to 4 4 to 10 10 to 30 30 to 50 over 50 Approximate Relative Density(%) 0 -15 15 -35 35 -65 65 -85 85 -100 COHESIVE SOILS Consistency Very Soft Soft Medium Stiff Stiff Very Stiff Hard N (blows/ft) 0 to 2 2 to 4 4 to 8 8 to 15 15 Clean Sand (little or no fines) 50% or More of Coarse Fraction Passing Fine Grained Soils Silt and Clay Liquid Limit Less than 50% 50% or More Passing No. 200 Sieve Size Silt and Clay Liquid Limit 50% or More 500 500 -1000 1000 -2000 2000 -4000 >4000 DensityDensity USCS SOIL CLASSIFICATION SYSTEM Coarse Grained Soils Gravel and Gravelly Soils Highly Organic Soils GROUP DESCRIPTIONS Well-graded GRAVEL Poorly-graded GRAVEL Silty GRAVEL Clayey GRAVEL Well-graded SAND Poorly-graded SAND Silty SAND Clayey SAND SILT Lean CLAY Organic SILT/Organic CLAY Elastic SILT Fat CLAY Organic SILT/Organic CLAY PEAT MAJOR DIVISIONS GW SP CL OL PT GP GM GC SW COHESIONLESS SOILS Fines (appreciable LEGEND 2016-136.GPJ 5/2/17 PROJECT NO.:FIGURE: Coarse sand Medium sand SIZE RANGE Larger than 12 in Smaller than No. 200 (0.074mm) Gravel time of drilling) Groundwater Level (measured in well or AL CBR CN Atterberg Limits:LL = Liquid Limit California Bearing Ratio Consolidation Resilient Modulus Photoionization Device Reading Pocket Penetrometer Specific Gravity Triaxial Compression Torvane 3 in to 12 in 3 in to No 4 (4.5mm) No. 4 (4.5 mm) to No. 200 (0.074 mm) COMPONENT DRY Absence of moisture, dusty, dry to the touch. MOIST Damp but no visible water. WET Visible free water, usually soil is below water table. Boulders Cobbles Coarse gravel Fine gravel Sand MOISTURE CONTENT COMPONENT PROPORTIONS Fine sand Silt and Clay 5 - 12% PROPORTION RANGE DESCRIPTIVE TERMS Clean Slightly (Clayey, Silty, Sandy) 30 - 50% Components are arranged in order of increasing quantities. Very (Clayey, Silty, Sandy, Gravelly) 12 - 30%Clayey, Silty, Sandy, Gravelly open hole after water level stabilized) Groundwater Level (measured at 3 in to 3/4 in 3/4 in to No 4 (4.5mm) No. 4 (4.5 mm) to No. 10 (2.0 mm) No. 10 (2.0 mm) to No. 40 (0.42 mm) No. 40 (0.42 mm) to No. 200 (0.074 mm) PL = Plastic Limit DD DS GS K MD MR PID PP SG TC TV Dry Density (pcf) Direct Shear Grain Size Distribution Permeability Approx. Shear Strength (tsf) Percent Fines%F Moisture/Density Relationship (Proctor) Approx. Compressive Strength (tsf) Unconfined CompressionUC (140 lb. hammer with 30 in. drop) Shelby Tube Small Bag Sample Large Bag (Bulk) Sample Core Run Non-standard Penetration Test 2.0" OD Split Spoon (SPT) NOTES: Soil classifications presented on exploration logs are based on visual and laboratory observation. Density/consistency, color, modifier (if any) GROUP NAME, additions to group name (if any), moisture content. Proportion, gradation, and angularity of constituents, additional comments. (GEOLOGIC INTERPRETATION) Please refer to the discussion in the report text as well as the exploration logs for a more complete description of subsurface conditions. Soil descriptions are presented in the following general order: < 5% 3-1/4" OD Split Spoon with Brass Rings (3.0" OD split spoon) TEST SYMBOLS SAMPLE TYPE SYMBOLS GROUNDWATER SYMBOLS COMPONENT DEFINITIONS GS GS GS %F GS S-1 S-2 S-3 S-4 S-5 S-6 S-7 S-8 S-9 S-10 Soft, dark brown, sandy SILT with organics, wet. (TOPSOIL) Medium stiff, brown, sandy SILT, moist. Sand is fine to medium. Rootlets, rust mottling, and scattered anoxic decomposition (black spots) visible throughout. (RECESSIONAL OUTWASH) Loose, brown, very sandy SILT, moist. Rootlets and rust banding observed. Trace coarse sand. Loose, olive brown, very silty, fine to coarse SAND, moist. Rust staining. Silty sand layer from 8.5 to 9.0 feet. Medium dense, olive brown, silty, medium to coarse SAND with trace gravel, moist. Gravel is subrounded to subangular. Medium dense, olive brown, silty, fine to medium SAND, moist. Becomes wet. Scattered rust bands observed. Becomes olive brown to olive gray, and moist. Medium dense, olive gray, fine clean SAND, moist. Rust band observed at 20.5'. Becomes fine to medium. Becomes mostly fine sand. Olive brown silty sand layers at 31.0'. Scattered oxidation bands. Boring terminated at 31.5 feet. No groundwater observed while conducting this exploratory boring. 1-1-3 3-1-3 4-5-4 5-6-7 5-7-8 5-8-9 5-6-10 5-6-7 6-9-11 6-8-9 ML SM SP BORING-DSM 2016-136.GPJ 8/31/17 FIGURE:PROJECT NO.:2016-136-21 Renton, Washington Renton Fire Statioin 15 BH-4 PAGE: 1 of 1(blows/6 inches)GROUNDWATERPEN. RESISTANCELiquid Limit (140 lb. weight, 30" drop) Blows per foot A-2 Standard Penetration Test NOTE: This log of subsurface conditions applies only at the specified location and on the date indicated DESCRIPTION OTHER TESTSPlastic Limit BORING: and therefore may not necessarily be indicative of other times and/or locations.SYMBOL0 10 20 30 40 50 0 20 40 60 80 100SAMPLE TYPESAMPLE NUMBERNatural Water ContentUSCS SOIL CLASSWater Content (%)DEPTH(feet)0 5 10 15 20 25 30 35 ELEVATION(feet)DATE COMPLETED: 3/29/2017 DRILLING COMPANY: Environmental Drilling Inc. DRILLING METHOD: B-61 Truck Rig with 4.25" IC Continuous Flight HSA LOCATION: 80.0' North of South fence; 53.9' West of East fence DATE STARTED: 3/29/2017 SAMPLING METHOD: SPT with auto-hammer LOGGED BY: B. Salazar SURFACE ELEVATION: Approx. 212 feet GS GS GS GS GS %F GS %F S-1 S-2 S-3 S-4 S-5 S-6 S-7 S-8 Soft, dark brown, sandy SILT with organics, wet. (TOPSOIL) Loose, dark yellowish brown, very silty SAND, moist. Rust mottling throughout sample. One gravel (1" diameter) observed at 3.0'. (RECESSIONAL OUTWASH) Medium dense, dark yellowish brown, silty, fine to medium SAND, wet. Rust bands observed throughout sample. Trace wood and some gravels at 6.0'. Clean sand band at 5.5' and 6.2'. Stiff, dark yellowish brown, very sandy SILT, moist. Bands of medium sand observed from 10.5' to 11.0'. Medium dense, dark brown, silty, fine to medium SAND, moist. Rust band observed at 13.8'. Medium dense, olive brown, slightly silty, fine to medium SAND, moist. Rust band observed at 15.3'. 2-3-5 2-3-8 3-5-8 2-3-6 4-7-11 6-6-8 5-8-8 5-7-9 SM ML SM SP SM BORING-DSM 2016-136.GPJ 5/2/17 FIGURE:PROJECT NO.:2016-136-21 Renton, Washington Renton Fire Statioin 15 BH-5 PAGE: 1 of 2(blows/6 inches)GROUNDWATERPEN. RESISTANCELiquid Limit (140 lb. weight, 30" drop) Blows per foot A-3 Standard Penetration Test NOTE: This log of subsurface conditions applies only at the specified location and on the date indicated DESCRIPTION OTHER TESTSPlastic Limit BORING: and therefore may not necessarily be indicative of other times and/or locations.SYMBOL0 10 20 30 40 50 0 20 40 60 80 100SAMPLE TYPESAMPLE NUMBERNatural Water ContentUSCS SOIL CLASSWater Content (%)DEPTH(feet)0 5 10 15 20 25 ELEVATION(feet)DATE COMPLETED: 3/29/2017 DRILLING COMPANY: Environmental Drilling Inc. DRILLING METHOD: B-61 Truck Rig with 4.25" IC Continuous Flight HSA LOCATION: 46.1' East of West fence; 77.2' North of South fence DATE STARTED: 3/29/2017 SAMPLING METHOD: SPT with auto-hammer LOGGED BY: B. Salazar SURFACE ELEVATION: Approx. 209 feet S-9 S-10 S-11 S-12 S-13 Becomes wet. Becomes saturated and fine at 32.5'. (WEATHERED TILL) Band of loose, gray, silty fine SAND, moist, from 37.5' to 38.0'. Trace coarse sand grains observed. Very stiff, olive brown, slightly sandy SILT, moist, from 38.0' to 38.5'. Rust banding throughout. Dense, olive brown, medium to coarse SAND with gravel, wet. Gravel is subrounded to subangular. Becomes silty fine SAND from 42.5' to 43.0. Rust banding observed. Boring terminated at 44 feet. No groundwater observed while conducting this exploratory boring (perched water possible at 32.5'). 6-9-11 3-5-7 5-11-13 9-26-28 7-10-17 SP SM SP BORING-DSM 2016-136.GPJ 5/2/17 FIGURE:PROJECT NO.:2016-136-21 Renton, Washington Renton Fire Statioin 15 BH-5 PAGE: 2 of 2(blows/6 inches)GROUNDWATERPEN. RESISTANCELiquid Limit (140 lb. weight, 30" drop) Blows per foot A-3 Standard Penetration Test NOTE: This log of subsurface conditions applies only at the specified location and on the date indicated DESCRIPTION OTHER TESTSPlastic Limit BORING: and therefore may not necessarily be indicative of other times and/or locations.SYMBOL0 10 20 30 40 50 0 20 40 60 80 100SAMPLE TYPESAMPLE NUMBERNatural Water ContentUSCS SOIL CLASSWater Content (%)DEPTH(feet)25 30 35 40 45 50 ELEVATION(feet)DATE COMPLETED: 3/29/2017 DRILLING COMPANY: Environmental Drilling Inc. DRILLING METHOD: B-61 Truck Rig with 4.25" IC Continuous Flight HSA LOCATION: 46.1' East of West fence; 77.2' North of South fence DATE STARTED: 3/29/2017 SAMPLING METHOD: SPT with auto-hammer LOGGED BY: B. Salazar >> SURFACE ELEVATION: Approx. 209 feet GS GS GS GS S-1 S-2 S-3 S-4 S-5 S-6 S-7 S-8 S-9 S-10 Soft, dark brown, sandy SILT with organics, wet. (TOPSOIL) Medium stiff, olive brown, sandy SILT, wet. Rust bands observed throughout sample. (RECESSIONAL OUTWASH) Driller notes gravelly drilling action at 4.5'. Loose, dark yellowish brown, very sandy SILT, moist to wet. Trace organics. Rust bands observed. Loose, dark yellowish brown, slightly silty, fine to medium SAND, moist. One oxidation band at 8.0'. Becomes medium dense. Medium dense, grayish brown, slightly silty, fine to medium SAND, moist. Becomes lighter olive gray. Driller notes gravelly drilling action at 29'. Trace coarse sand in sampler tip (31.5'). Boring terminated at 31.5 feet. No groundwater observed while conducting this exploratory boring. 2-3-3 2-2-4 4-4-5 5-6-7 5-6-8 4-6-6 3-3-7 4-6-10 3-6-8 8-11-14 ML SM SP SM BORING-DSM 2016-136.GPJ 5/2/17 FIGURE:PROJECT NO.:2016-136-21 Renton, Washington Renton Fire Statioin 15 BH-6 PAGE: 1 of 1(blows/6 inches)GROUNDWATERPEN. RESISTANCELiquid Limit (140 lb. weight, 30" drop) Blows per foot A-4 Standard Penetration Test NOTE: This log of subsurface conditions applies only at the specified location and on the date indicated DESCRIPTION OTHER TESTSPlastic Limit BORING: and therefore may not necessarily be indicative of other times and/or locations.SYMBOL0 10 20 30 40 50 0 20 40 60 80 100SAMPLE TYPESAMPLE NUMBERNatural Water ContentUSCS SOIL CLASSWater Content (%)DEPTH(feet)0 5 10 15 20 25 30 35 ELEVATION(feet)DATE COMPLETED: 3/29/2017 DRILLING COMPANY: Environmental Drilling Inc. DRILLING METHOD: B-61 Truck Rig with 4.25" IC Continuous Flight HSA LOCATION: 138.9' North of South fence; 35.0' West of East fence DATE STARTED: 3/29/2017 SAMPLING METHOD: SPT with auto-hammer LOGGED BY: B. Salazar SURFACE ELEVATION: Approx. 214 feet S-1 S-2 S-3 S-4 GS +HYD GS +HYD GS +HYD SM ML SPSM 15 9 17 Medium dense, light olive brown, silty, fine to medium SAND, dry, scattered roots.(TOPSOIL) Medium dense, olive brown, sandy SILT, moist,trace coarse grains, trace fine to large gravel. (RECESSIONAL OUTWASH) Large boulder partially exposed in west wall of test pit. Medium dense, olive brown, slightly silty, fineto medium SAND, moist. Test pit terminated at 13' feet.Small scale pilot infiltration test performed at 7feet. Renton, Washington 2016-136-21 FIGURE: SMART TP 2016-136.GPJ 8/31/17 Renton Fire Statioin 15 PAGE: 1 of 1 TP-2 LOG OF TEST PIT PROJECT NO.: and therefore may not necessarily be indicative of other times and/or locations. NOTE: This log of subsurface conditions applies only at the specified location and on the date indicated A-5 EXCAVATION COMPANY: Kelly's Excavating EXCAVATING EQUIPMENT:SAMPLE NUMBERLOGGED BY: A. York DATE COMPLETED: 7/25/17 LOCATION: 120' N of S fence; 40' E of W fence.SYMBOLOTHER TESTSUSCS SOIL CLASSMOISTUE CONTENT (%)SAMPLE TYPEDEPTH (feet)0 5 10 15 DESCRIPTION TEST PIT PHOTO APPENDIX B LABORATORY TESTING Renton FS 15 - Revised Final Report 12212017 B-1 HWA GEOSCIENCES INC APPENDIX B LABORATORY TESTING Representative soil samples obtained from the explorations were returned to the HWA laboratory for further examination and testing. Laboratory tests were conducted on selected soil samples to characterize relevant engineering properties of the on-site materials. The laboratory testing program was performed in general accordance with appropriate ASTM Standards as outlined below. MOISTURE CONTENT: The moisture contents of selected soil samples were determined in general accordance with ASTM D 2216. The results are shown at the sampled intervals on the appropriate summary logs in Appendix A. PARTICLE SIZE ANALYSIS OF SOILS: The particle size distribution of selected soil samples was determined in general accordance with ASTM D422. The results are summarized on the attached Grain Size Distribution reports, Figures B-1 through B-7, which also provide information regarding the classification of the sample, and the moisture content at the time of testing. 0 10 20 30 40 50 60 70 80 90 100 0.0010.010.1110 Coarse #60#40 PARTICLE-SIZE ANALYSIS OF SOILS METHOD ASTM D422 50.4 40.5 12.6 #20 Fine Coarse SYMBOL Gravel% 3"1-1/2"PERCENT FINER BY WEIGHT#4 #200 1.0 2.1 7.0 Sand% (ML)Dark yellowish brown, sandy SILT (SM) Dark yellowish brown, silty SAND (SM) Dark yellowish brown, silty SAND Fines% 27 21 10 GRAIN SIZE IN MILLIMETERS 50 SAMPLE S-2 S-3 S-4 5.0 - 6.5 7.5 - 9.0 10.0 - 11.5 #10 48.6 57.4 80.4 30 CLASSIFICATION OF SOIL- ASTM D2487 Group Symbol and Name U.S. STANDARD SIEVE SIZES SAND CLAY BH-4 BH-4 BH-4 SILT 3/4" GRAVEL 0.05 5/8" 70 #100 0.5 50 Medium Fine 3/8" 5 PI 90 10 % MC LL PLDEPTH ( ft.) B-1 0.00050.005 2016-136-21PROJECT NO.: HWAGRSZ 2016-136.GPJ 8/31/17 FIGURE: Renton Fire Statioin 15 Renton, Washington 0 10 20 30 40 50 60 70 80 90 100 0.0010.010.1110 Coarse #60#40 PARTICLE-SIZE ANALYSIS OF SOILS METHOD ASTM D422 13.0 14.2 29.9 #20 Fine Coarse SYMBOL Gravel% 3"1-1/2"PERCENT FINER BY WEIGHT#4 #200 8.0 Sand% (SM) Dark yellowish brown, silty SAND (SM) Dark yellowish brown, silty SAND (SM) Dark yellowish brown, silty SAND Fines% 20 17 22 GRAIN SIZE IN MILLIMETERS 50 SAMPLE S-6 S-7 S-1 15.0 - 16.5 17.5 - 19.0 2.5 - 4.0 #10 85.8 62.1 30 CLASSIFICATION OF SOIL- ASTM D2487 Group Symbol and Name U.S. STANDARD SIEVE SIZES SAND CLAY BH-4 BH-4 BH-5 SILT 3/4" GRAVEL 0.05 5/8" 70 #100 0.5 50 Medium Fine 3/8" 5 PI 90 10 % MC LL PLDEPTH ( ft.) B-2 0.00050.005 2016-136-21PROJECT NO.: HWAGRSZ 2016-136.GPJ 8/31/17 FIGURE: Renton Fire Statioin 15 Renton, Washington 0 10 20 30 40 50 60 70 80 90 100 0.0010.010.1110 Coarse #60#40 PARTICLE-SIZE ANALYSIS OF SOILS METHOD ASTM D422 41.0 15.6 51.0 #20 Fine Coarse SYMBOL Gravel% 3"1-1/2"PERCENT FINER BY WEIGHT#4 #200 8.6 3.7 0.2 Sand% (SM) Dark yellowish brown, silty SAND (SM) Dark yellowish brown, silty SAND (ML) Dark yellowish brown, sandy SILT Fines% 21 13 26 GRAIN SIZE IN MILLIMETERS 50 SAMPLE S-2 S-3 S-4 5.0 - 6.5 7.5 - 9.0 10.0 - 11.5 #10 50.5 80.7 48.8 30 CLASSIFICATION OF SOIL- ASTM D2487 Group Symbol and Name U.S. STANDARD SIEVE SIZES SAND CLAY BH-5 BH-5 BH-5 SILT 3/4" GRAVEL 0.05 5/8" 70 #100 0.5 50 Medium Fine 3/8" 5 PI 90 10 % MC LL PLDEPTH ( ft.) B-3 0.00050.005 2016-136-21PROJECT NO.: HWAGRSZ 2016-136.GPJ 8/31/17 FIGURE: Renton Fire Statioin 15 Renton, Washington 0 10 20 30 40 50 60 70 80 90 100 0.0010.010.1110 Coarse #60#40 PARTICLE-SIZE ANALYSIS OF SOILS METHOD ASTM D422 13.1 10.0 10.4 #20 Fine Coarse SYMBOL Gravel% 3"1-1/2"PERCENT FINER BY WEIGHT#4 #200 0.0 Sand% (SM) Dark brown, silty SAND (SP-SM) Olive brown, poorly graded SAND with silt (SP-SM) Olive brown, poorly graded SAND with silt Fines% 18 14 15 GRAIN SIZE IN MILLIMETERS 50 SAMPLE S-5 S-6 S-7 12.5 - 14.0 15.0 - 16.5 17.5 - 19.0 #10 86.8 89.6 30 CLASSIFICATION OF SOIL- ASTM D2487 Group Symbol and Name U.S. STANDARD SIEVE SIZES SAND CLAY BH-5 BH-5 BH-5 SILT 3/4" GRAVEL 0.05 5/8" 70 #100 0.5 50 Medium Fine 3/8" 5 PI 90 10 % MC LL PLDEPTH ( ft.) B-4 0.00050.005 2016-136-21PROJECT NO.: HWAGRSZ 2016-136.GPJ 8/31/17 FIGURE: Renton Fire Statioin 15 Renton, Washington 0 10 20 30 40 50 60 70 80 90 100 0.0010.010.1110 Coarse #60#40 PARTICLE-SIZE ANALYSIS OF SOILS METHOD ASTM D422 8.9 62.4 12.4 #20 Fine Coarse SYMBOL Gravel% 3"1-1/2"PERCENT FINER BY WEIGHT#4 #200 0.5 0.2 Sand% (SP-SM) Grayish brown, poorly graded SAND with silt (ML) Dark yellowish brown, sandy SILT (SM) Dark yellowish brown, silty SAND Fines% 13 31 20 GRAIN SIZE IN MILLIMETERS 50 SAMPLE S-8 S-2 S-4 20.0 - 21.5 5.0 - 6.5 10.0 - 11.5 #10 37.1 87.4 30 CLASSIFICATION OF SOIL- ASTM D2487 Group Symbol and Name U.S. STANDARD SIEVE SIZES SAND CLAY BH-5 BH-6 BH-6 SILT 3/4" GRAVEL 0.05 5/8" 70 #100 0.5 50 Medium Fine 3/8" 5 PI 90 10 % MC LL PLDEPTH ( ft.) B-5 0.00050.005 2016-136-21PROJECT NO.: HWAGRSZ 2016-136.GPJ 8/31/17 FIGURE: Renton Fire Statioin 15 Renton, Washington 0 10 20 30 40 50 60 70 80 90 100 0.0010.010.1110 Coarse #60#40 PARTICLE-SIZE ANALYSIS OF SOILS METHOD ASTM D422 9.0 9.1 61.4 #20 Fine Coarse SYMBOL Gravel% 3"1-1/2"PERCENT FINER BY WEIGHT#4 #200 0.1 0.7 Sand% (SP-SM) Grayish brown, poorly graded SAND with silt (SP-SM) Grayish brown, poorly graded SAND with silt (ML)Olive brown, sandy SILT Fines% 12 12 15 GRAIN SIZE IN MILLIMETERS 50 SAMPLE S-6 S-8 S-2 15.0 - 16.5 20.0 - 21.5 2.0 - 3.0 #10 91.0 90.8 37.9 30 CLASSIFICATION OF SOIL- ASTM D2487 Group Symbol and Name U.S. STANDARD SIEVE SIZES SAND CLAY BH-6 BH-6 TP-2 SILT 3/4" GRAVEL 0.05 5/8" 70 #100 0.5 50 Medium Fine 3/8" 5 PI 90 10 % MC LL PLDEPTH ( ft.) B-6 0.00050.005 2016-136-21PROJECT NO.: HWAGRSZ 2016-136.GPJ 8/31/17 FIGURE: Renton Fire Statioin 15 Renton, Washington 0 10 20 30 40 50 60 70 80 90 100 0.0010.010.1110 Coarse #60#40 PARTICLE-SIZE ANALYSIS OF SOILS METHOD ASTM D422 7.6 9.5 #20 Fine Coarse SYMBOL Gravel% 3"1-1/2"PERCENT FINER BY WEIGHT#4 #200 0.0 Sand% (SP-SM) Olive brown, poorly graded SAND with silt (SP-SM) Light gray, poorly graded SAND with silt Fines% 9 17 GRAIN SIZE IN MILLIMETERS 50 SAMPLE S-3 S-4 7.0 - 8.0 8.0 - 9.0 #10 92.4 90.5 30 CLASSIFICATION OF SOIL- ASTM D2487 Group Symbol and Name U.S. STANDARD SIEVE SIZES SAND CLAY TP-2 TP-2 SILT 3/4" GRAVEL 0.05 5/8" 70 #100 0.5 50 Medium Fine 3/8" 5 PI 90 10 % MC LL PLDEPTH ( ft.) B-7 0.00050.005 2016-136-21PROJECT NO.: HWAGRSZ 2016-136.GPJ 8/31/17 FIGURE: Renton Fire Statioin 15 Renton, Washington APPENDIX C ADDITIONAL EXPLORATIONS A-12016-078-21 Kennydale 320 Pressure Zone Reservoir Renton, Washington LEGEND OF TERMS AND SYMBOLS USED ON EXPLORATION LOGS RELATIVE DENSITY OR CONSISTENCY VERSUS SPT N-VALUE COHESIONLESS SOILS Density Very Loose Loose Medium Dense Very Dense Dense N (blows/ft) 0 to 4 4 to 10 10 to 30 30 to 50 over 50 Approximate Relative Density(%) 0 - 15 15 - 35 35 - 65 65 - 85 85 - 100 COHESIVE SOILS Consistency Very Soft Soft Medium Stiff Stiff Very Stiff Hard N (blows/ft) 0 to 2 2 to 4 4 to 8 8 to 15 15 to 30 over 30 Approximate Undrained Shear Strength (psf) <250 250 - 500 500 - 1000 1000 - 2000 2000 - 4000 >4000 ASTM SOIL CLASSIFICATION SYSTEM MAJOR DIVISIONS Coarse Grained Soils Gravel and Gravelly Soils Clean Gravel (little or no fines) More than 50% of Coarse Fraction Retained on No. 4 Sieve Gravel with Fines (appreciable amount of fines) More than 50% Retained on No. 200 Sieve Size Sand and Sandy Soils Clean Sand (little or no fines) 50% or More of Coarse Fraction Passing No. 4 Sieve Sand with Fines (appreciable amount of fines) Fine Grained Soils Silt and Clay Liquid Limit Less than 50% 50% or More Passing No. 200 Sieve Size Silt and Clay Liquid Limit 50% or More Highly Organic Soils GROUP DESCRIPTIONS GW GP GM GC SW SP SM SC ML CL OL MH CH OH PT Well-graded GRAVEL Poorly-graded GRAVEL Silty GRAVEL Clayey GRAVEL Well-graded SAND Poorly-graded SAND Silty SAND Clayey SAND SILT Lean CLAY Organic SILT/Organic CLAY Elastic SILT Fat CLAY Organic SILT/Organic CLAY PEAT PZOLEGEND 2016-078.GPJ 11/22/16 PROJECT NO.:FIGURE: TEST SYMBOLS GS %F CN TX UC DS M PP TV CBR MD PID AL Grain Size Distribution Percent Fines Well Cap Concrete Seal 5 - Well Casing Bentonite Seal Groundwater Level (measured at time of drilling) Groundwater Level (measured in well after water level stabilized) Slotted Well Casing Consolidation Triaxial Compression Unconfined Compression Direct Shear Resilient Modulus Pocket Penetrometer Approx. Compressive Strength (tsf) Torvane Approximate Shear Strength (tsf) California Bearing Ratio Moisture/Density Relationship < Photoionization Device Reading Atterberg Limits:PL Plastic Limit LL Liquid Limit SAMPLE TYPE SYMBOLS 2.0" OD Split Spoon (SPT) (140 lb. hammer with 30 in. drop) Shelby Tube 3.0" OD Split Spoon with Brass Rings Small Bag Sample Large Bag (Bulk) Sample Core Run Non-standard Penetration Test (with split spoon sampler) COMPONENT PROPORTIONS Very (Clayey, Silty, Sandy, Gravelly) RANGEOF PROPORTIONDESCRIPTIVE TERMS Slightly (Clayey, Silty, Sandy) Sand Backfill GROUNDWATER WELL COMPLETIONS Locking Well Security Casing MOISTURE CONTENT DRY Absence of moisture, dusty, dry to the touch. Clean MOIST Damp but no visible water. WET Visible free water, usually soil is below water table. COMPONENT DEFINITIONS COMPONENT Boulders Cobbles Gravel Coarse gravel Fine gravel Sand Coarse sand Medium sand Fine sand Silt and Clay SIZE RANGE Larger than 12 in 3 in to 12 in 3 in to No 4 (4.5mm) 3 in to 3/4 in 3/4 in to No 4 (4.5mm) No. 4 (4.5 mm) to No. 200 (0.074 mm) No. 4 (4.5 mm) to No. 10 (2.0 mm) No. 10 (2.0 mm) to No. 40 (0.42 mm) No. 40 (0.42 mm) to No. 200 (0.074 mm) Smaller than No. 200 (0.074mm) NOTES: Soil classifications presented on exploration logs are based on visual and laboratory observation in general accordance with ASTM D 2487 and ASTM D 2488. Soil descriptions are presented in the following general order: Density/consistency, color, modifier (if any) GROUP NAME, additions to group name (if any), moisture content. Proportion, gradation, and angularity of constituents, additional comments. (GEOLOGIC INTERPRETATION) Please refer to the discussion in the report text as well as the exploration logs for a more complete description of subsurface conditions. 12% 12 - 30% 30 - 50% 5% Clayey, Silty, Sandy, Gravelly S-1 S-2 S-3 S-4 S-5 S-6 S-7 S-8 S-9 S-10 GS GS GS GS ML SM SP 1-2-2 3-7-6 4-6-7 5-7-8 4-5-9 3-5-9 10-19-24 5-7-14 6-12-14 4-9-13 Soft, brown, organic, sandy SILT, moist. (TOPSOIL) Loose, light olive brown, very sandy SILT, moist. Trace coarse sand. Scattered roots and rust mottling. (RECESSIONAL OUTWASH) Alternating bands of medium dense, olive gray and olive brown, silty, fine to medium SAND, moist. Bands are up to 1" in thickness. Trace roots. Medium dense, olive brown, slightly silty, fine to medium SAND, moist. Rust band observed at 8.1'. Medium dense, olive brown, very silty, fine to medium SAND, moist. Band of olive brown, silty fine sand from 12.9'-13.4'. Medium dense, olive gray, clean, fine to medium SAND, moist. Bands of olive brown, silty fine sand up to 2" thick throughout sample. Dense, gray, clean, fine to coarse SAND, moist. Becomes more dry with fine gravels increasing in abundance starting at 18.6'. Possibly overstated blow counts due to gravel in sampler. Medium dense, olive gray, fine to medium SAND, moist. Trace coarse sand and fine gravel. Trace rust mottling. Medium dense, gray, clean, fine to coarse SAND with fine gravel, moist. Medium dense, gray, clean, fine to medium SAND, moist. Trace fine gravel. One bad of coarse sand from 28.7' to 28.8'. 0 20 40 60 80 100 Water Content (%) Plastic Limit (140 lb. weight, 30" drop) Blows per foot (blows/6 inches)USCS SOIL CLASSDESCRIPTION SAMPLE TYPESAMPLE NUMBERPEN. RESISTANCEOTHER TESTSPIEZOMETERStandard Penetration Test A-2SYMBOLSCHEMATIC01020304050 Liquid Limit BORING: BH-1 PAGE: 1 of 2 Water Content (%) Natural Water ContentNOTE: This log of subsurface conditions applies only at the specified location and on the date indicatedand therefore may not necessarily be indicative of other times and/or locations. PZO-DSM 2016-078.GPJ 1/3/17 FIGURE:PROJECT NO.:2016-078-21 Renton, Washington Kennydale 320 Pressure Zone ReservoirDEPTH(feet)0 5 10 15 20 25 30 ELEVATION(feet)DATE COMPLETED: 11/10/2016 DRILLING COMPANY: Environmental Drilling Inc. DRILLING METHOD: B-61 Truck Rig with 4.25" ID continuous flight HSA LOCATION: 55.2' west of eastern fence line; 54.7' south of northern fence line DATE STARTED: 11/10/2016 SAMPLING METHOD: SPT with auto-hammer LOGGED BY: B. Salazar S-11 S-12 S-13 S-14 S-15 SM 10-15-18 10-12-16 15-28-27 50/6" 12-37-50/4" Dense, olive gray, slightly silty, fine to medium SAND, moist. Medium dense, olive gray, clean, fine to medium SAND, moist. Becomes fine sand at 38.5'. Driller notes hard drilling at 40'. Very dense, olive brown, silty, fine to medium SAND with minor fine gravel, moist. Faint rust mottling. (GLACIAL TILL) Very dense, olive brown, silty, fine to medium SAND, moist. Very dense, olive brown, silty, fine to medium SAND with gravel, moist. Boring terminated at 51.3 feet. No groundwater observed while conducting this exploratory boring. Piezo well installed. Well tag #BIZ317. Groundwater observed at 46.6 feet bgs on 11/11/2016. 0 20 40 60 80 100 Water Content (%) Plastic Limit (140 lb. weight, 30" drop) Blows per foot (blows/6 inches)USCS SOIL CLASSDESCRIPTION SAMPLE TYPESAMPLE NUMBERPEN. RESISTANCEOTHER TESTSPIEZOMETERStandard Penetration Test A-2SYMBOLSCHEMATIC01020304050 Liquid Limit BORING: BH-1 PAGE: 2 of 2 Water Content (%) Natural Water ContentNOTE: This log of subsurface conditions applies only at the specified location and on the date indicatedand therefore may not necessarily be indicative of other times and/or locations. PZO-DSM 2016-078.GPJ 1/3/17 FIGURE:PROJECT NO.:2016-078-21 Renton, Washington Kennydale 320 Pressure Zone ReservoirDEPTH(feet)30 35 40 45 50 55 60 ELEVATION(feet)DATE COMPLETED: 11/10/2016 DRILLING COMPANY: Environmental Drilling Inc. DRILLING METHOD: B-61 Truck Rig with 4.25" ID continuous flight HSA LOCATION: 55.2' west of eastern fence line; 54.7' south of northern fence line DATE STARTED: 11/10/2016 SAMPLING METHOD: SPT with auto-hammer LOGGED BY: B. Salazar >> >> >> GS GS GS GS %F S-1 S-2 S-3 S-4A S-4B S-5 S-6 S-7A S-7B S-8 S-9 S-10 Soft, brown, organic, sandy SILT, moist. (TOPSOIL) Medium dense, light olive brown, very sandy SILT, moist. Trace coarse sand and fine gravel. Roots. Rust mottling around gravels. (RECESSIONAL OUTWASH) Medium dense, olive brown, very silty, fine to medium SAND, moist. Rust mottling and trace roots throughout sample. Scattered lenses of olive gray clean fine to medium sand. Medium dense, olive brown, silty, fine to medium SAND, dry/moist. Trace roots. Medium dense, olive brown, silty, fine to medium SAND, moist. Becomes clean at 11.0'. Medium dense, olive gray, fine to medium, poorly graded SAND, with silt, moist. Medium dense, olive gray, fine to medium SAND with trace fine gravel and silt, moist. One silty fine sand lens from 16.0 to 16.2'. Medium dense, olive brown, sandy SILT, moist. Thinly bedded. Medium dense, olive gray, clean, fine to coarse SAND with fine gravel, moist. Grain size increases with depth. Medium dense, olive gray, clean, fine to medium SAND, moist. Trace coarse sand and fine gravel. Poor recovery during sample. Medium dense, gray, fine to medium SAND with fine gravel, moist. Gravel increases in abundance with depth. 2-5-14 7-9-9 7-9-8 6-7-9 4-7-7 5-5-9 5-7-14 4-6-11 5-8-11 6-11-15 ML SM SP SM ML SP BORING-DSM 2016-078.GPJ 1/3/17 FIGURE:PROJECT NO.:2016-078-21 Renton, Washington Kennydale 320 Pressure Zone Reservoir BH-2 PAGE: 1 of 3(blows/6 inches)GROUNDWATERPEN. RESISTANCELiquid Limit (140 lb. weight, 30" drop) Blows per foot A-3 Standard Penetration Test NOTE: This log of subsurface conditions applies only at the specified location and on the date indicated DESCRIPTION OTHER TESTSPlastic Limit BORING: and therefore may not necessarily be indicative of other times and/or locations.SYMBOL0 10 20 30 40 50 0 20 40 60 80 100SAMPLE TYPESAMPLE NUMBERNatural Water ContentUSCS SOIL CLASSWater Content (%)DEPTH(feet)0 5 10 15 20 25 30 ELEVATION(feet)DATE COMPLETED: 11/9/2016 DRILLING COMPANY: Environmental Drilling Inc. DRILLING METHOD: B-61 Truck Rig with 4.25" ID continuous flight HSA LOCATION: 71.6' west of eastern fence line; 72.0' south of northern fence line DATE STARTED: 11/9/2016 SAMPLING METHOD: SPT with auto-hammer LOGGED BY: B. Salazar S-11 S-12 S-13A S-13B S-14 S-15 S-16 Dense, olive gray, clean, fine to coarse SAND, moist. Becomes fine to medium. Becomes wet. Dense, olive brown, silty SAND, moist. Trace fine gravel. More gravel in sampler tip. (GLACIAL TILL) Drillers report gravelly drilling at 45' Hard, olive brown, fine sandy SILT, moist. Rust mottling. Trace coarse sand. Very dense, gray, silty SAND with gravel, moist. Very dense, gray, silty, fine SAND with trace coarse sand and fine gravel, moist. Becomes olive brown from 53.5' to 54'. Very dense, gray, silty SAND with gravel, moist. Weathered sandstone in sampler from 57.5' to 58'. 10-17-27 9-14-16 13-14-22 11-25-43 21-32-50/6" 33-50/3" SP SM SM BORING-DSM 2016-078.GPJ 1/3/17 FIGURE:PROJECT NO.:2016-078-21 Renton, Washington Kennydale 320 Pressure Zone Reservoir BH-2 PAGE: 2 of 3(blows/6 inches)GROUNDWATERPEN. RESISTANCELiquid Limit (140 lb. weight, 30" drop) Blows per foot A-3 Standard Penetration Test NOTE: This log of subsurface conditions applies only at the specified location and on the date indicated DESCRIPTION OTHER TESTSPlastic Limit BORING: and therefore may not necessarily be indicative of other times and/or locations.SYMBOL0 10 20 30 40 50 0 20 40 60 80 100SAMPLE TYPESAMPLE NUMBERNatural Water ContentUSCS SOIL CLASSWater Content (%)DEPTH(feet)30 35 40 45 50 55 60 ELEVATION(feet)DATE COMPLETED: 11/9/2016 DRILLING COMPANY: Environmental Drilling Inc. DRILLING METHOD: B-61 Truck Rig with 4.25" ID continuous flight HSA LOCATION: 71.6' west of eastern fence line; 72.0' south of northern fence line DATE STARTED: 11/9/2016 SAMPLING METHOD: SPT with auto-hammer LOGGED BY: B. Salazar >> >> >> S-17 S-18 S-19 Very dense, olive gray to gray, silty, fine SAND with gravel, moist. Trace coarse sand above sampler tip. Hard, olive brown, sandy SILT, moist. Rust at lower contact. Drillers noted earier drilling at 64'. (ADVANCE OUTWASH) Very dense, gray, silty, fine SAND with trace gravel, moist. Angled clean sand layer at 68.5' Very dense, gray, gravelly SAND with silt, wet. Poor recovery. Boring terminated at 73 feet. Groundwater observed at 43.5 feet while conducting this exploratory boring. 50/6" 14-21-28 50/6" SM SP BORING-DSM 2016-078.GPJ 1/3/17 FIGURE:PROJECT NO.:2016-078-21 Renton, Washington Kennydale 320 Pressure Zone Reservoir BH-2 PAGE: 3 of 3(blows/6 inches)GROUNDWATERPEN. RESISTANCELiquid Limit (140 lb. weight, 30" drop) Blows per foot A-3 Standard Penetration Test NOTE: This log of subsurface conditions applies only at the specified location and on the date indicated DESCRIPTION OTHER TESTSPlastic Limit BORING: and therefore may not necessarily be indicative of other times and/or locations.SYMBOL0 10 20 30 40 50 0 20 40 60 80 100SAMPLE TYPESAMPLE NUMBERNatural Water ContentUSCS SOIL CLASSWater Content (%)DEPTH(feet)60 65 70 75 80 85 90 ELEVATION(feet)DATE COMPLETED: 11/9/2016 DRILLING COMPANY: Environmental Drilling Inc. DRILLING METHOD: B-61 Truck Rig with 4.25" ID continuous flight HSA LOCATION: 71.6' west of eastern fence line; 72.0' south of northern fence line DATE STARTED: 11/9/2016 SAMPLING METHOD: SPT with auto-hammer LOGGED BY: B. Salazar >> >> GS GS GS GS S-1 S-2 S-3 S-4 S-5 S-6 S-7 S-8 S-9 Soft, dark brown, organic, sandy SILT, moist. Roots. (TOPSOIL) Loose, olive brown, very silty, fine to medium SAND, moist. Trace fine gravels. Rust mottling throughout. Roots. (RECESSIONAL OUTWASH) Medium dense, olive brown, silty, fine to medium SAND, moist. Roots, scattered rust bands. Medium dense, olive gray, clean SAND, moist. Trace silt. Thinly bedded. Scattered rust bands. Becomes slightlty silty. Bedding becomes massive. Medium dense, olive gray, silty, fine to medium SAND, moist. Scattered rust mottling observed. Silt band observed from 21'-21.3'. Some fine gravels from 21.3'-21.5'. Boring terminated at 21.5 feet. No groundwater observed while conducting this exploratory boring. 1-2-1 2-4-5 4-7-10 5-6-7 5-7-8 4-5-6 4-7-10 4-5-7 4-6-8 SM SP SM SM BORING-DSM 2016-078.GPJ 1/3/17 FIGURE:PROJECT NO.:2016-078-21 Renton, Washington Kennydale 320 Pressure Zone Reservoir BH-3 PAGE: 1 of 1(blows/6 inches)GROUNDWATERPEN. RESISTANCELiquid Limit (140 lb. weight, 30" drop) Blows per foot A-4 Standard Penetration Test NOTE: This log of subsurface conditions applies only at the specified location and on the date indicated DESCRIPTION OTHER TESTSPlastic Limit BORING: and therefore may not necessarily be indicative of other times and/or locations.SYMBOL0 10 20 30 40 50 0 20 40 60 80 100SAMPLE TYPESAMPLE NUMBERNatural Water ContentUSCS SOIL CLASSWater Content (%)DEPTH(feet)0 5 10 15 20 25 30 ELEVATION(feet)DATE COMPLETED: 11/9/2016 DRILLING COMPANY: Environmental Drilling Inc. DRILLING METHOD: B-61 Truck Rig with 4.25" ID continuous flight HSA LOCATION: 43.5' east of western fence line; 75.9' south of northern fence line DATE STARTED: 11/9/2016 SAMPLING METHOD: SPT with auto-hammer LOGGED BY: B. Salazar S-1 S-2 S-3 S-4 GS+HYD GS+HYD SM SM SPSM 10 10 Medium dense, light olive brown, silty, fine SAND, dry to moist, trace coarse sand,scattered roots.(RECESSIONAL OUTWASH) Stiff, olive brown, very silty, fine SAND, grades to very silty, fine SAND, moist, non-plastic, withscattered fine to large gravel and cobbles. Medium dense, olive brown, slightly silty, fineto medium SAND, moist, olive greyish brown at 8'. Medium dense, olive greyish brown, slightlysilty to clean, fine to medium SAND, moist,some caving at 13'. Renton, Washington 2016-078-21 FIGURE: SMART TP 2016-078.GPJ 8/31/17 Kennydale 320 Pressure Zone Reservoir PAGE: 1 of 2 TP-1 LOG OF TEST PIT PROJECT NO.: and therefore may not necessarily be indicative of other times and/or locations. NOTE: This log of subsurface conditions applies only at the specified location and on the date indicated A-5 EXCAVATION COMPANY: EXCAVATING EQUIPMENT:SAMPLE NUMBERLOGGED BY: A. York DATE COMPLETED: 7/25/17 LOCATION: 75' S of N fence; 40' E of W fence SYMBOLOTHER TESTSUSCS SOIL CLASSMOISTUE CONTENT (%)SAMPLE TYPEDEPTH (feet)0 5 10 15 DESCRIPTION TEST PIT PHOTO S-5 GS+HYDSPSM7 Medium dense, olive greyish brown, slightly silty to clean, fine to medium SAND, moist. Test pit terminated at 19 feet.Pilot infiltration test performed at 16 feet. Renton, Washington 2016-078-21 FIGURE: SMART TP 2016-078.GPJ 8/31/17 Kennydale 320 Pressure Zone Reservoir PAGE: 2 of 2 TP-1 LOG OF TEST PIT PROJECT NO.: and therefore may not necessarily be indicative of other times and/or locations. NOTE: This log of subsurface conditions applies only at the specified location and on the date indicated A-5 EXCAVATION COMPANY: EXCAVATING EQUIPMENT:SAMPLE NUMBERLOGGED BY: A. York DATE COMPLETED: 7/25/17 LOCATION: 75' S of N fence; 40' E of W fence SYMBOLOTHER TESTSUSCS SOIL CLASSMOISTUE CONTENT (%)SAMPLE TYPEDEPTH (feet)15 20 25 30 DESCRIPTION TEST PIT PHOTO 21312 30th Drive SE Suite 110 Bothell, WA 98021.7010 Tel: 425.774.0106 Fax: 425.774.2714 www.hwageo.com Federal & State Certified DBE / MWBE Geotechnical & Pavement Engineering  Hydrogeology  Geoenvironmental  Inspection & Testing GEOTECHNICAL MEMORANDUM PERMEABLE PAVEMENT RECOMMENDATIONS RENTON FIRE STATION 15, RENTON, WA To: SSW Architects Attn: Mary Jo Lux, AIA From: Sandy Brodahl, P.E., HWA GeoSciences Inc. Date: January 30, 2018 ______________________________________________________________________________ This memorandum provides geotechnical recommendations in support of the design infiltration facilities and permeable pavement for the Renton Fire Station project in Renton Washington. It is our understanding that a bioretantion pond and pervious concrete pavement will be designed considering stormwater quantity, quality using BMP’s in compliance with City of Renton 2016 Surface Design Manual (RSWDM). The near surface soils at both locations (for the bioretantion pond and permeable pavement are not conducive of infiltration. Therefore, we recommend over- excavating the upper fine-grained material (sandy silt soils) to expose the clean native soils and backfilling with permeable ballast meeting the requirements per WSDOT Standard Specification 9-03.9(2) (WSDOT, 2016). The RSWDM requires that runoff from pollution generating surfaces be infiltrated into soils that meet the groundwater protection criteria specified on Section 1.2.8: Core Requirement #8: Water Quality Facilities. To determine if the soils meet the required criteria, HWA performed cation exchange capacity (CEC) and organic content (OC) tests (test results attached) on the subgrade soils beneath the proposed infiltration facility. The results of the laboratory testing is summarized in Table 1, below. Table 1. Summary of Laboratory Testing Results Sample Designation CEC OC BH-6, S-5 5.8 BH-6, S-3 6.5 BH-4, S-5 1.3% BH-6, S-7 1.4% HWA Project No. 2016-136 January 30, 2018 Page 2 of 4 The CEC and OC test results indicated that both soils exceeded the requirements for treatability for CEC (5 meq/cc) and OC (0.5% by weight). In addition, the infiltration rate determined for the subgrade soils beneath the proposed infiltration facility (1.1 in/hr) does not exceed the maximum allowed for treatment of 2.4 in/hr. Therefore, we conclude that soils beneath the proposed infiltration facility meet the criteria required by the Soil treatment Exemption (No. 4) of Section 1.2.8, of the RSWDM. Pervious Concrete Pavement Design Recommendations In general, pervious pavement sections consist of; a wearing course, a choker course, a recharge bed course, placed over carefully prepared subgrade. Regardless of the type of the wearing course used, the size and composition of the remaining courses are generally the same. Table 1 presents our recommendations for the pervious concrete pavement section. It should be noted that sandy silt soils containing a high percentage of fine material were encountered near the ground surface (about 5-7 feet below ground surface). These soils are not conducive to infiltration. Therefore, we recommend over-excavating the upper fine-grained material (sandy silt soils) to expose the clean native soils and backfilling with permeable ballast meeting the requirements per WSDOT Standard Specification 9-03.9(2) (WSDOT, 2016). The granular material placed underneath the pervious pavement should be compacted to a dense and unyielding condition while keeping compaction equipment movement over the subgrade to a minimum. The following sections provide our recommendations for each component of the pervious pavement section. Table 2. Pavement Section Requirements for New Pervious PCC Pavement Material Description Minimum Layer Thickness (inches) WSDOT Standard Specification PCC Wearing Surface 6 5-05 Choker Course (AASHTO No. 57) 1 Section 9-03.1(4)C- Recharge Bed (AASHTO No. 2) Varies (18-36) Section 5.05.2 Non-Woven Geosynthetic - 9-33.2(1) Prepared Subgrade Uncompacted Section 5.05.3 HWA Project No. 2016-136 January 30, 2018 Page 3 of 4 Pervious Portland Cement Concrete Based on the anticipated light loading conditions and the nature of pervious concrete pavement, it is our recommendation that this pavement section consist of a minimum of 6 inches of pervious Portland cement concrete pavement. Pervious Portland cement concrete is typically a proprietary product that is available from many local concrete batch plants. In general, the pervious concrete mix uses uniformly graded crushed coarse aggregate (e.g. meeting AASHTO grading No. 8) with no, or limited use of, fine aggregate and a water/cement ratio ranging from 0.27 to 0.35. The 28-day compressive strength of the mix is typiclly between 2,500 psi and 4,000 psi with an average modulus of rupture of about 350 to 375 psi. The unit weight of the mix is between 100 and 125 pcf with a porosity of 15% to 25%. The initial permeability of the hardened product is between 300 and 800 in/hr. We recommend that expansion joints be saw cut into the concrete at spacings of no greater than 12 feet to limit post construction cracking. These joints need not be sealed. Maintenance practices for cleaning pervious concrete should be implemented to maintain permeability. Some cleaning techniques are pressure washing, vacuum sweeping and/or a combination of these two methods. Recharge Bed Design and Subgrade Preparation Recharge beds under pervious pavements should be adequately sized to provide sufficient storage during the 2-year design storm, and should also include an overflow system (or under- drain system) to handle peak inflows of more intense (25 or 50-year) storms. Typical bed thicknesses range between 1.5 feet and 3 feet. The drain aggregate in the recharge bed should consist of 1 inch to 1.5 inch crushed, washed drain rock, or 1.5 to 2.5 inch washed crushed base aggregate meeting the gradation requirements for AASHTO No. 2. The coarse gravel should be placed in 8-inch thick (maximum) loose lifts with each layer compacted to a firm and unyielding condition while keeping compaction equipment movement over recharge bed subgrade to a minimum. A design value of 0.3 should be used for the porosity of the base aggregate. A 1-inch thick choker course consisting of uniformly graded gravel, such as size AASHTO No.57 aggregate, should be placed over the surface of the recharge bed to provide a platform for the porous wearing surface. A nonwoven geotextile meeting the material requirements of WSDOT Standard Specifications (WSDOT, 2016) Section 9-33.1, with the properties listed in Section 9-33.2(1) Table 3 for Separation, should be placed along the sides of the excavation between the native and the drain aggregate to prevent migration of fines into the recharge bed. The nonwoven geotextile should HWA Project No. 2016-136 January 30, 2018 Page 4 of 4 not be placed below the pervious wearing surface over the top of the recharge bed aggregate. Placing nonwoven geotextile below the pervious wearing surface could result in clogging of the geotextile over time, reducing the functionality of the system. Enclosures: Cation Exchange Capacity Lab Results Material Laboratory Report (Organic Content) cc. Sophia Nespor, LPD Engineering Laurie Pfarr, LPD Engineering HWA GEOSCIENCES 21312 30TH DRIVE SE, STE 110 BOTHELL , WA 98021 1/16/2018 Soil BH-6 S-5 S18-00489 Date Received: Grower: Sampled By: Field: Laboratory #: Test Results Customer Account #: Customer Sample ID: Other Tests: Cation Exchange meq/100gCEC 5.8 pH 1:1 E.C. 1:1 m.mhos/cm Est Sat Paste E.C. m.mhos/cm Effervescence Ammonium - N mg/kg %Organic Matter W.B. $13.00This is your Invoice #: List Cost:KEBReviewed by:S18-00489 Account #188200 We make every effort to provide an accurate analysis of your sample. For reasonable cause we will repeat tests, but because of factors beyond our control in sampling procedures and the inherent variability of soil, our liability is limited to the price of the tests. Recommendations are to be used as general guides and should be modified for specific field conditions and situations. Note: "u" indicates that the element was analyzed for but not detected HWA GEOSCIENCES 21312 30TH DRIVE SE, STE 110 BOTHELL , WA 98021 1/16/2018 Soil BH-6 S-3 S18-00488 Date Received: Grower: Sampled By: Field: Laboratory #: Test Results Customer Account #: Customer Sample ID: Other Tests: Cation Exchange meq/100gCEC 6.5 pH 1:1 E.C. 1:1 m.mhos/cm Est Sat Paste E.C. m.mhos/cm Effervescence Ammonium - N mg/kg %Organic Matter W.B. $13.00This is your Invoice #: List Cost:KEBReviewed by:S18-00488 Account #188200 We make every effort to provide an accurate analysis of your sample. For reasonable cause we will repeat tests, but because of factors beyond our control in sampling procedures and the inherent variability of soil, our liability is limited to the price of the tests. Recommendations are to be used as general guides and should be modified for specific field conditions and situations. Note: "u" indicates that the element was analyzed for but not detected DenisLawMayorCommunity&EconomicDevelopmentC.E.“Chip”Vincent,AdministratorFebruary9,2018LauriePfarr,P.E.LPDEngineering,Inc.193215tAvenue,Suite201Seattle,WA98101RE:FireStation15(C17005383)—ADSStormTechChamberSystem-Adjustment2018-01(LUA7-000632)DearMs.Pfarr:TheCityofRentonhascompletedthereviewoftheenclosedadjustmentrequestfortheFireStation15projectinaccordancewithCityadopted2017RentonSurfaceWaterDesignManual(RSWDM)towhichtheprojectisvestedtoinaccordanceRMC4-1-045.Astheapplicant’sengineer,youarerequestinganadjustmentfrom2017RSWDMtoSection5.1,DetentionFacilities.TheadjustmentrequestproposestouseStormlechSC-740ChamberSystemasadetentionfacility.TheADSStormTechSC-740ChamberSystemisnotincludedintheCity’sadopted2017RSWDMasanapproveddetentionfacility,butjurisdictionslikeKingCounty,Bothell,Seattle,andtheCityofRentonhaveapprovedtheuseofthesefacilitiesthroughanadjustment/varianceprocess.Findings:1.Theprojectsiteislocatedat1404N.30thStreet(KingCountyParcel3342103245).Theexistingparcelisapproximately47,532squarefeetinsize.Theprojectsiteisthesouthernportionoftheexistingparcelwhichisapproximately31,173squarefeetinsize.Theparcelisproposedtobesubdividedatalaterdate.Theprojectsiteiscurrentlyvacantandcoveredwithgrassyareasandtrees.ThefuturenorthernparcelwillcontainanewCityofRentonwaterreservoir.Thesiteworkforthewaterreservoirsitewillbeapprovedunderaseparateconstructionpermit.2.Theprojectproposestoconstructanewfirestationwithaperviouspavementparkinglotandotherlandscapingandsiteimprovements.AnasphaltsharedaccessdrivewayisproposedtobeconstructedalongthewesternpropertylineforaccesstotherearofthefirestationandthefutureCityofRentonwaterreservoir.3.TheflowcontrolstandardapplicabletotheprojectisthePeakRateFlowControlStandardMatchingExistingConditions.1055SouthGradyWay,Renton,WA98057.rentonwa.gov Ms.LauriePfarr,P.E.Page2of5February9,20184.Theproposedprojectwillcreateapproximately23,010squarefeetofimpervioussurfaceand9,035ofpervioussurfaceafterdevelopmentoftheprojectsiteandinstallationoffrontageimprovementsintheN.30thStreetrightofway.5.TheADSStormTechSC-740ChamberSystemisproposedandsizedtodetainsurfacewaterrunofffromaportionofthefirestationroof,thesharedaccessdriveway,thedrivewayfromtheparkinglottothefirestationgarage,theon-sitelandscaping,andon-sitewalkways.Theparkinglotintherearofthefirestationwillconsistofperviousconcretepavementallowingsurfacewatertoinfiltrateintotheground.Theremainderofthesurfacewaterrunofffromtheroofandthedrivewayfromtheparkinglottothefirestationgaragewillberoutedtoabiorententionfacilitywithaninfiltrationtrenchallowingsurfacewatertoinfiltrateintotheground.6.TheADSStormlechSC-740ChamberSystemandotherproposedon-sitedrainagefacilitieswillbeprivatelyownedandmaintained.TheADSStormlechSC-740ChamberSystemisnotapprovedforuseforprivatelyorpublicly(City)ownedandmaintainedstormsystemswithoutanapprovedstormwateradjustment.7.TheADSStormTechSC-740ChamberSystemislocatedonthesitesothatitcanbemaintainedbyavactortruckparkedinthesharedaccessdriveway.Thedistancefromtheedgeofthesharedaccessdrivewaytothefurthest(eastern)catchbasinontheisolatorrowisapproximately65feet.Basedontheinformationprovidedintheenclosedadjustmentrequest,theADSStormTechSC-740ChamberSystemforflowcontrolisapprovedfortheproposedFireStation15withthefollowingconditions:Conditions:1.TheADSStormTechSC-740ChamberSystemshallbedesignedperSection5.1.2—DetentionTanksofthe2017RSWDM.TheADSStormTechSC-740ChamberSystemasshownintheCivilConstructionPlansdesignedandprovidedbyLPDEngineeringisapprovedasdesignedwithachamberheightof30”insteadofthe36”diameterrequiredbySection5.1.2.2.ThemanifoldsystemfortheinlettotheADSStormlechSC-740ChamberSystemshallbeabletovisuallybeinspectedfromtheinletmanholewiththeoverflowweir.Theweirshallberemovablesuchthatvisualinspectionofthemanifoldisfeasible.3.CatchbasinsformaintenanceaccessshallbelocatedateachendoftheisolatorrowoftheADSStormTechSC-740ChamberSystem.4.MaintenancestandardsspecifictotheADSStormTechSC-740ChamberSystemsshallbeincludedintheTechnicalInformationReport.5.TheADSStormTechSC-740ChamberSystemmustbeinstalledinanareathatisaccessibletomaintenanceequipment.ThemaintenanceoftheADSStormTechSC-740ChamberSystemrequiresavacuumtruck.Themanholecovers,and/oraccesshatchesoftheSystemmustbeplacedinlocationsthatcanbeeasilyreachedbysuchavehicle.1055SouthGradyWay,Renton,WA98057rentonwa.gov Ms.LauriePfarr,P.E.Page3of5February9,201810.InstallationoftheADSStormTechSC-740ChamberSystemshallfollowtheManufacturer’srecommendedinstallationandmaintenanceprocedures.11.TheADSStormlechSC-740ChamberSystemshallbeinstalledinaccordancewiththeCityapprovedconstructionplans.As-builtconstructionplansshallbeprovidedpriortoissuanceoftheFinalCertificateofOccupancyforFireStation15.12.TheADSStormTechSC-740ChamberSystemwillbeprivatelyownedandmaintainedbythePropertyOwner.13.IfitisdeterminedthatthePropertyOwnerisunabletoproperlymaintainthesystemasdesigned,thePropertyOwnerwillberesponsibleforexploringotheravenuestomaintainthesystemandobtainingconcurrencewiththeManufacturerthattherevisedmaintenanceoption(s)is/areanacceptablemethodofperformingmaintenancetotheADSStormTechSC-740ChamberSystem.14.Facilityinspection,maintenance,andreportingarerequiredbytheCityofRentonSurfaceWaterUtilityforthePropertyOwnermaintainedADSStormTechSC-740ChamberSysteminperpetuity.Thefacilityinspection,maintenance,andreportingisrequiredpertheEcologyNationalPollutantDischargeEliminationSystemPhaseIIMunicipalStormwaterPermit(SectionS5.C.4.c.iii).Facilityownersareresponsibleforensuringthatstormwaterfacilitiesareproperlymaintainedandfunctioningasdesignedandpermitted.15.TheADSStormTechSC-740ChamberSystemshallbeinspectedandmaintainedinaccordancewithManufacturerrecommendationsand,inaddition,beinspectedandmaintainedasdetailedbelow:a.Forthefirsttwoyearsafterconstruction,theADSStormTechSC-740ChamberSystemshallbeinspectedeverysixmonthstoassureproperperformance.Inspectionreportswillbeusedtodeterminefuturesite-specificmaintenanceschedulesandrequirements.b.Followingthefirstyearofoperation,thefacilityowner(s)shallannuallyhavetheADSStormTechSC-740ChamberSysteminspectedandmaintainedpertheproceduresinthemostrecentversionoftheADSStormTechSC-740ChamberSystemOperationandMaintenanceManuals.AllwrittenrecordsoftheinspectionandmaintenanceshallbesubmittedtotheCityofRentonSurfaceWaterUtility,totheattentionofSurfaceWaterUtilityPrivateStormwaterFacilityInspectionProgram.IfmorefrequentinspectionandmaintenanceoftheADSStormiechSC-740ChamberSystemisrequiredbytheManufacturerorisneededtoensureperformanceofthefacility,thentheadditionalinspectionandmaintenancereportscompletedwithintheyearshallbeprovidedwiththeannualreport.1055SouthGradyWay,Renton,WA98057rentonwa.gov Ms.LauriePfarr,P.E.Page4of5February9,2018c.Uponcompletionofthetwo-yearinspectionperiodafterconstructionoftheADSStormTechSC-740ChamberSystem,theCitywillreviewtheinspectionreportandfacilitymaintenancelogtore-evaluatefutureinspectionfrequencyofthesystem.Theinformationwillbeusedtodetermineiftheminimuminspectionfrequencyofonceayearcanbeallowed.d.Maintenanceactivities,toassureproperperformanceoftheADSStormTechSC-740ChamberSystemsshallbeasneeded,orasdeterminedintheannualinspection,tocomplywiththerequirementsinthe2017RSWDMformaintenanceofdrainagefacilities.Inaddition,maintenanceproceduresshouldfollowthosegiveninthemostrecentversionoftheADSStormlechSC-740ChamberSystemOperationandMaintenanceManual.16.TheapplicantwillneedtosubmitaDrainageFacilityCovenantfortheFireStation15ProjecttoallowtheCityaccesstothefacilityforinspectionoftheADSStormiechSC-740ChamberSystemthatwillbeprivatelymaintained.ThecurrentDrainageFacilityCovenantcanbeontheCity’swebsiteintheCivilConstructionPermitDocumentsSection.ThecurrentDrainageFacilityCovenantcanbefoundhere:https://edocs,rentonwa.gov/Documents/0/edoc/963417/Declaration%2Oof%2oCovenant%20-%2ODrainage%2OFacilities%20and%200n-Site%2OBMPs.pdf.Asiteplanshowingthelocationofthedetentionfacilityalongwithallotheron-siteprivatestormwaterinfrastructuremustbeincludedasExhibitAwiththeDeclarationofCovenant.AdraftoftheDrainageFacilityCovenantshallbeprovidedpriortoConstructionPermitissuance.TheDrainageFacilityCovenantwillberecordeduponthecompletionoftheproject.AnychangestothedrainagefacilityshallbeshownonanupdatedExhibitApriortorecording.17.Theapprovalofthisadjustmentdoesnotrelievetheapplicantfromothercity,state,orfederalrequirements.18.TheapprovalofthisadjustmenttousetheADSStormTechSC-740ChamberSystemsforthisprojectdoesnotauthorizetheuseoftheADSStormTechSC-740ChamberSystemsonfutureprojectswithoutpriorapprovalfromtheCityofRenton.1055SouthGradyWay,Renton,WA98057rentonwa.gov Ms.LauriePfarr,P.E.Page5of5February9,2018Ifyouhaveanyquestionsaboutthisadjustment,pleasecontactBrianneBannwarth,DevelopmentEngineeringManager,at(425)430-7299orRonStraka,SurfaceWaterUtilityEngineeringManager,at(425)430-7248.Sincerely,BrianneBannwart,P.E.DevelopmentEngineeringManagercc:IanFitz-James,P.E.,CivilEngineerIllLysHornsby,P.E.,UtilitySystemsDirectorGaryFink,CivilEngineerIllClarkClose,SeniorPlannerRonaldJ.Straka,P.E.SurfaceWaterUtilityEngineeringManagerH:\FileSys\SWP-SurfaceWaterProjects\SWP-27-SurfaceWaterProjects(CIP)\27-3129RentonStormwaterManual\ADJUSTMENTS\2018\2018-1FireStation15-ADAStormTechChamberSystem.docx1055SouthGradyWay,Renton,WA98057rentonWa.gov