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EX_05_RP_CUP_TIR_241112_v1
EXHIBIT 5 RECEIVED 12/17/2024 JDing PLANNING DIVISION Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 LPD Engineering, PLLC Page 21 Renton Fire Station #16 Technical Information Report, November 12, 2024 RENTON FIRE STATION #16 TECHNICAL INFORMATION REPORT TABLE OF CONTENTS Section 1 – Project Overview .................................................................................................................................. 1 Section 2 – Conditions and Requirements Summary ........................................................................................ 3 Section 3 – Offsite Analysis ...................................................................................................................................... 6 Section 4 – Flow Control, Low Impact Development (LID) and Water Quality Facility Analysis and Design ............................................................................................................................................................................. 9 Section 5 – Conveyance Systems Analysis and Design ................................................................................... 12 Section 6 – Special Reports and Studies .............................................................................................................. 12 Section 7 – Other Permits ...................................................................................................................................... 13 Section 8 – CSWPPP Analysis and Design ......................................................................................................... 13 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 3: Downstream Drainage Map 1 Figure 4: Downstream Drainage Map 2 Figure 5: Soils Map Figure 6: Proposed Conditions Figure 7: Proposed Modeled Conditions APPENDICES Appendix A – Design Drawings Appendix B – Design Calculations and Supporting Information Appendix C – Construction Stormwater Pollution Prevention Plan (SWPPP) Narrative Appendix D – Operations and Maintenance Manual Appendix E – Declaration of Drainage Covenant Appendix F – Special Reports and Studies Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 LPD Engineering, PLLC Page 1 Renton Fire Station #16 Technical Information Report, November 12, 2024 RENTON FIRE STATION #16 REPLACEMENT TECHNICAL INFORMATION REPORT NOVEMBER 12, 2024 SECTION 1 – PROJECT OVERVIEW This Technical Information Report (TIR) is for the replacement of the Renton Fire Station #16 for the Renton Regional Fire Authority, located at 15815 SE 128th St in Renton, Washington. Refer to Figure 1 – TIR Worksheet for basic site information. The proposed project site is comprised of four parcels (parcel numbers: 3664500008, 3664500330, 3664500009, and 3664500007). The project site is bounded by SE 128th St to the north, a neighboring church property to the east, single family residential properties to the west and south, and 158th Ave SE along the southwestern side. The project site can be accessed from SE 128th St in the north and from 158th Ave SE in the southwest corner. The site is located in Section 14, Township 23 North, Range 5 East, Willamette Principal Meridian. Refer to Figure 2 – Vicinity Map. The project site is currently developed with single-family structures and gravel driveways. The project proposes to demolish the existing on-site structures and redevelop the site with a new Fire Station building in the north, maintenance building, driveway and parking areas. The project also proposes improvements to the adjacent right of ways along SE 128th St and 158th Ave SE. The storm drainage design will be in accordance with the requirements of the 2022 Surface Water Design Manual amendment (RSWDM) and 2021 King County Surface Water Design Manual (KCSWDM) as adopted by the City of Renton, as well as, additional stormwater requirements in the City of Renton Code and the City’s Standard Details. Existing Conditions and Hydrology The project site parcel is approximately 3.38 acres (147,314 SF). According to City of Renton critical areas mapping, there are no designated sensitive areas on the existing site. The current zoning classification for all of the subject parcels is R-4 Residential and located within the City of Renton. GeoEngineers, Inc. completed a Geotechnical Report, dated August 5th, 2022. Their field study included 10 exploration borings across the site ranging between 10.5 to 50.5 feet below the ground surface. The explorations typically encountered existing fill soils, generally consisting of soft/loose to medium dense sandy silt/silty sand with variable organic and gravel content ranging between 2 to 7.5 feet below the ground surface. Below the fill soils weathered glacial till soils, which consisted of medium dense to dense silty sand, were observed between 4 to 9 feet below the ground surface. Very dense unweathered glacial till soils, consisting of very dense silty sand with variable gravel content, beginning at a depth ranging from about 5 to 10 feet below the ground surface and extending to the depths explored were observed below the layer of weathered glacial till. Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 LPD Engineering, PLLC Page 2 Renton Fire Station #16 Technical Information Report, November 12, 2024 Based upon GeoEngineers evaluation, the on-site soils are not suitable for infiltration. Per Section 5.0: “Design of infiltration facilities will be constrained at the site because of the relatively high percentage of fines and low permeability of the native glacial soils. We anticipate the native glacial soils will have a very slow infiltration rate (permeability on the order of 10-5 to 10 6 centimeters per second or typical infiltration rates less than 0.1 inches per hour). Furthermore, we anticipate a seasonally perched groundwater will be present above the weathered glacial till and/or relatively unweathered glacial till soils. Depending on the design configuration, below-grade infiltration facilities are likely not feasible due to seasonally perched groundwater and the hydraulic restrictive layers encountered at the site.”. The full Geotechnical Report is attached in Appendix F. Topographically, the site slopes down from the southwest to the northeast from a high elevation of approximately 548-feet at the southwest corner of the westernmost parcel (3664500009). The lowest point on the multiple parcel property sits at approximately 529-feet at the northeast corner of the easternmost parcel (3664500330) adjacent to SE 128th Street. The project site has two threshold discharge areas that discharge to separate drainage basins. Threshold Discharge Area 1 (TDA 1) includes the majority of the stormwater from the site, flows norther-easterly to discharge to May Creek drainage basin. Threshold Discharge Area 2 (TDA 2) includes a small area on the southwestern most parcel, and flows southerly, and discharges to the Lower Cedar River drainage basin. Refer to the Offsite Analysis section of this report for further information. Proposed Site Improvements and Hydrology The proposed project improvements will include a Fire Station building and maintenance building with a central driveway connecting access to both buildings, and 158th Ave SE and SE 128th St. There will be three parking areas, one located in the northeast corner, one located south of the fire station building and one located south of the maintenance building. Refer to Figure 6 – Proposed Conditions. Per coordination with the City of Renton, improvements will be made to the frontage along SE 128th St to support two proposed driveways, a sidewalk and street trees. Frontage on 158th Ave SE will be improved to support the southwest driveway access and frontage improvements. The project will also include a 905 feet 8-inch diameter public sewer mainline extension in 158th Ave SE from the site to existing 8-inch diameter public sewer mainline in SE 132nd PL. Sewer stubs will be provided for each residence. The utility installation will remove and replace the existing roadway pavement with in kind material per City of Renton Standards as well as grind and overlay the existing pavement to full extents of the west lane. The project proposes 82,759 SF (1.90 acres) total of new plus replaced impervious surface. In order to preserve the drainage patterns of the existing site, the post-developed grading of the project site has been designed to maintain the existing threshold discharge areas, to the extent feasible. TDA 1 is comprised of 4.24 acres located within the project site and adjacent right-of-way along SE 128th St, with 80,924 SF (1.86 acres) of new plus replaced impervious surface. Refer to Figure 6 – Proposed Conditions, for a visual representation of the proposed project areas. Stormwater runoff from TDA 1 will be collected in a series of catch basins and trench drains and routed via pipe conveyance systems to one of two detention facilities, an SC-740 StormTech Chamber system Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 LPD Engineering, PLLC Page 3 Renton Fire Station #16 Technical Information Report, November 12, 2024 located in the north portion of the site and a detention vault located in the eastern area of the site. Both systems will have a flow control structure to attenuate flows. Pollution generating surfaces will be routed to Modular Wetland System for water quality treatment prior to entering the detention facilities. The detained and treated discharge will discharge to the existing ditch near the northeast corner of the site at SE 128th St. TDA 2 is comprised of 0.14 acres of onsite pervious surface and right-of-way improvements on the east side of 158th Ave SE, with 1,835 SF (0.04 acres) of new plus replaced impervious surface. Refer to Figure 6 – Proposed Conditions, for a visual representation of the proposed project areas. Stormwater runoff from TDA 2 will be collected in a culvert in the right-of-way on the east side of 158th Ave SE. The stormwater will continue to follow the existing downstream pathway. Refer to Section 4 – Flow Control and Water Quality Analysis and Design for further information on the storm drainage design. SECTION 2 – CONDITIONS AND REQUIREMENTS SUMMARY Per Figure 1.1.2.A, Flow Chart for Determining Type of Drainage Review Required of the RSWDM, the project is subject to a Full Drainage Review because it results in greater than 2,000 square feet (SF) of new plus replaced impervious surface, is not defined as a large project or single-family residential project and results in less than 50 acres of new impervious surface. Per Table 1.1.2.A, Requirements Applied Under Each Drainage Review Type, the TIR addresses Core Requirements (CR) 1 through 9 and Special Requirements (SR) 1 through 6 of the 2022 RSWDM. Additionally, per the RSWDM Chapter 1, the project is not considered a redevelopment project as the existing impervious coverage is less than 35%. This section addresses the requirements set forth by the 2022 Renton SWDM, Core and Special Requirements listed in Chapter 1. Core Requirements Core Requirement 1 – Discharge at Natural Location (1.2.1): The proposed conditions will maintain the existing discharge locations. As mentioned previously, the site is divided into two threshold discharge area, TDA 1 and TDA 2. Flow control detention facilities and BMPs will be implemented, thus attenuating discharge from the project area and creating no adverse impacts on the downstream system. Refer to the Offsite Analysis section of this report for a description of the existing discharge points from the site. Core Requirement 2 – Off-site Analysis (1.2.2): A Level 1 Downstream Analysis is in Section 3, Task 4. Core Requirement 3 – Flow Control (1.2.3): The proposed project improvements in TDA 1 are greater than 5,000 SF of new plus replaced impervious surface. Per the City of Renton Flow Control Application Map, the project site is located within Flow Control Duration Standard area. Therefore, the flow duration of predeveloped rates for forested (historical) site conditions over the range of flows extending from 50% of 2-year up to the full 50- year flow AND matches peaks for the 2- and 10-year return periods. Per the RSWDM, flow control facilities must mitigate the runoff from the target surfaces which include new and replaced Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 LPD Engineering, PLLC Page 4 Renton Fire Station #16 Technical Information Report, November 12, 2024 impervious surfaces that are not fully dispersed and new pervious surfaces that are not fully dispersed. For further information regarding the flow control design, refer to Section 4 of this report. The proposed project improvements in TDA 2 result in less than 5,000 SF of new plus replaced impervious surface AND less than ¾ acres of new pervious surface will be added. Therefore, the proposed improvements in TDA 2 meet the criteria for the Basic Exemption and flow control is not required. Core Requirement 4 – Conveyance System (1.2.4): Refer to Section 5 of this report for conveyance analysis. Core Requirement 5 – Erosion and Sedimentation Control (1.2.5): A Temporary Erosion and Sediment Control (TESC) plan has been included with the plan set. 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 any demolition, clearing, grubbing or construction. Core Requirement 6 – Maintenance and Operations (1.2.6): The Operations and Maintenance Manual for the project is 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 proposed project improvements in TDA 1 result in more than 5,000 SF of new plus replaced pollution-generating impervious surface (PGIS), and therefore water quality treatment is required. As Fire Stations are considered a commercial land use, Enhanced Basic Water Quality Treatment is required. For further information regarding the water quality design requirements, refer to Section 4 of this report. The proposed project improvements in TDA 2 result in less than 5,000 SF of new plus replaced pollution-generating impervious surface (PGIS) AND less than ¾ acre of new pollution-generating pervious surface. Per the RSWDM Exemptions from Core Requirement #8, this area meets Exemption 1 Surface Area and therefore water quality treatment for TDA 2 is not be required. Core Requirement 9 – On-Site BMPs (1.2.9): The proposed improvements in TDA 1 result in more than 2,000 SF of new plus replaced impervious surfaces, therefore an evaluation of BMP feasibility for all target surfaces is required. Per section 1.2.9.2 of the RSWDM, this project area will be subject to Large Lot BMP Requirements since the project site is larger than 22,000 SF. Refer to the On-Site BMPs evaluation within Section 4 of this report. The proposed improvements in TDA 2 also result in less than 2,000 SF of new plus replaced impervious surfaces, therefore an evaluation of BMP feasibility for all target surfaces is not required. Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 LPD Engineering, PLLC Page 5 Renton Fire Station #16 Technical Information Report, November 12, 2024 Special Requirements Special Requirement 1 – Other Adopted Area-Specific Requirements (1.3.1): The City of Renton Surface Water Design Manual is one of several adopted regulations in the City of Renton that apply requirements for controlling drainage on an area-specific basis. Other adopted area-specific regulations include requirements that have a more direct bearing on the drainage design of a proposed project. These regulations include the following: • Master Drainage Plans (MDPs) – The project is not within an area covered by an approved Master Drainage Plan. Project is not a Master Planned Development, a Planned Unit Development, a subdivision that will have more than 100 lots, a commercial development that will construct more than 50 acres of impervious surface, and will not clear more than 500 acres within a drainage sub-basin. Therefore, a Master Drainage Plan is not required. • Basin Plans (BPs) – The Watershed Management Committee Lower Cedar River Basin and Nonpoint Pollution Action Plan, adopted 1997, was reviewed to determine if there are regulations applicable to this site. There are no additional water quality requirements listed by the report. • Salmon Conservation Plans (SCPs) – The project is not within an area governed by SCPs. • Lake Management Plans (LMPs) – The project is not within an area governed by an LMP. • Hazard Mitigation Plan – The proposed project is not within an area with a Hazard Mitigation Plan. • Shared Facility Drainage Plans (SFDPs) – The proposed project is not within an area with an SFDP. Special Requirement 2 – Flood Hazard Area Delineation (1.3.2): According to King County iMap, the project does not contain nor is it adjacent to a Flood Hazard Area. Special Requirement 3 – Flood Protection Facilities (1.3.3): The project does not have existing flood protection facilities, nor does it propose new flood protection facilities. Special Requirement 4 – Source Control (1.3.4): The applicable water quality source controls are evaluated based on RSWDM Section 1.3.4. The proposed conditions, kitchen facilities will involve activity A-8 listed within the 2022 King County Stormwater Pollution Prevention Manual (KCSPPM) that will require the use of source control measures. Activity A-8 includes storage of solid and food wastes (including cooking grease). Therefore, a grease interceptor will be required as a source control measure. Vehicle washing will be completed within the bays of the building, which drain to the sewer. Special Requirement 5 – Oil Control (1.3.5): Per the Definitions Section of the RSWDM, the project will not be considered a high-use site nor is it an existing high-use site. The expected average daily traffic count is expected to be less than 100 vehicles per day, which is far less than 100 vehicles per 1,000 square feet of gross building area (2400 vehicles per day). It is not subject to petroleum storage or transfer in excess of 1,500 gallons per year and it will maintain of a fleet of 14 vehicles that are over 10 tons net weight, which is less than threshold of 25. Therefore, oil control is not required. Special Requirement 6 – Aquifer Protection Area (1.3.6): The project is not located within an aquifer protection area. Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 LPD Engineering, PLLC Page 6 Renton Fire Station #16 Technical Information Report, November 12, 2024 SECTION 3 – OFFSITE ANALYSIS The following is the Level 1 downstream analysis for the proposed project. Task 1 – Study Area Definition and Maps The downstream analysis was completed using the Site Survey, King County iMap, City of Renton GIS Mapping, an onsite investigation on May 8th, 2024 and the Geotechnical Report dated August 5th 2022. The detailed topographic information for the project area is shown in the design drawings. Refer to Figure 3 – Downstream Drainage Map 1 and Figure 4 – Downstream Drainage Map 2. Task 2 – Resource Review Basin Summary According to the site survey and GIS mapping, the project is situated within two threshold discharge areas to two drainage basins. The majority of the site is tributary to the May Creek drainage basin. A small portion of the southwestern area of the site is tributary to the Cedar River drainage basin. May Creek and the Cedar River both ultimately discharge to Lake Washington at approximately 4 miles downstream. Floodway Map The site is not located within a Floodway or Floodplain per the Washington State Department of Ecology Flood Maps and King County iMap. Sensitive Areas The following is a summary of SAO sensitive areas located within the project area or within the downstream drainage course from the project area. The King County iMap application was used to examine the SAOs. SAO Erosion Hazard – The project site and downstream areas are not located within an erosion hazard area. SAO Seismic Hazard – The project site and downstream areas are not located within a seismic hazard area. SAO Landslide Hazard – There are no landslide hazard areas located within or downstream of the project site. SAO Coal Mine – There are no coal mines located within or downstream of the project site. SAO Stream –There are no unclassified stream or any waterbodies through the project site. SAO Wetland – There is a Type 1 wetland located approximately 0.31 miles downstream of the project site and a Type 2 wetland located approximately 0.5 miles downstream of the project site. Groundwater Contamination – The project site is located in an area susceptible to groundwater contamination. It is not anticipated that this project will impact groundwater contamination. Sole Source Aquifer – The project site and downstream areas are not located within a sole source aquifer area. Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 LPD Engineering, PLLC Page 7 Renton Fire Station #16 Technical Information Report, November 12, 2024 Critical Aquifer Recharge Area – The project site downstream areas are not considered a Critical Aquifer Recharge Area. Channel Migration Hazard – The project site and downstream areas are not located within a channel migration hazard zone. Soils Survey Refer to Section 1 of this report and Figure 5 - Soils Map for soils information. Wetlands Inventory According to City of Renton Mapping, there are no wetlands located within or directly adjacent to the project area. Section 303d List of Polluted Waters As mentioned previously, the majority of the project area is tributary to May Creek. According to the Washington State Department of Ecology’s Clean Water Act Section 303d list of polluted waters approximately 3 miles downstream of the site, a section of May Creek is listed as a Category 5 Waterbody due to temperature. It is not anticipated that this project will impact the temperature of May Creek. Landslide and Erosion According to City of Renton Mapping there are no landscape or erosion hazard zones located within or downstream of the project area. Task 3 – Field Inspection A field inspection and Level 1 Downstream analysis was conducted by LPD on May 7, 2024 to verify the on-site conditions, downstream drainage paths, and upstream basins. The weather during the site investigation was clear and sunny, with a temperature of approximately 65 degrees Fahrenheit. Task 4 – Drainage System Description and Problem Descriptions Below is a description of each TDA to a distance of approximately one-quarter mile downstream. TDA 1 The stormwater runoff from the site sheet flows towards the northern eastern corner where it discharges from the site into an existing open ditch system. Refer to Figure 3 – Downstream Drainage Map 1. From here the downstream path is as follows: 1. Stormwater is conveyed east along SE 128th St via an open ditch line for approximately 68-feet before entering a 12-inch concrete pipe system. 2. Stormwater is conveyed east via the 12-inch concrete pipe system for approximately 129-feet before entering a catch basin where the system transitions to 18-inch diameter concrete. 3. The stormwater is conveyed east along SE 128th St via the 18-inch concrete piped system for approximately 1840-feet, passing the ¼-mile mark downstream of the project site. 4. The stormwater enters an 18-inch plastic pipe system and is conveyed south for approximately 14 feet before the system becomes 24-inch diameter plastic pipe. 5. The stormwater is conveyed east via the 24-inch plastic pipe system for approximately 44-feet before reaching a catch basin. Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 LPD Engineering, PLLC Page 8 Renton Fire Station #16 Technical Information Report, November 12, 2024 6. The stormwater exits the catch basin and is conveyed east for approximately 35-feet via a 24- inch diameter concrete pipe before entering another catch basin. 7. The stormwater exits the catch basin and is conveyed southeast conveyed via a 24-inch diameter corrugated polyethylene pipe for approximately 41-feet before flowing into a 6-foot bioretention swale maintained by King County. 8. The stormwater discharges from the bioretention swale into a stream approximately 0.31 miles from the site. 9. The stream flows north along 164th Ave SE, through a series of open ditch lines and driveway culverts before crossing 164th Ave SE. The stormwater eventually discharges to May Creek approximately 1 mile from the site. May Creek outlets to Lake Washington. TDA 2 A small portion of stormwater runoff from the southern area of the site sheet flows towards 158th Ave SE and enters into the existing ditch line system along the east side of 158th Ave SE. Refer to Figure 4 – Downstream Drainage Map 2. From here the downstream path is as follows: 1. Stormwater flows south along 158th Ave SE conveyed through a series of open ditch line and culverts for approximately 460 feet before reaching a shared driveway and entering a 12-inch diameter concrete piped system. 2. Stormwater continues south along 158th Ave SE conveyed via the 12-inch diameter concrete pipe system for approximately 332 feet before reaching the intersection of 158th Ave SE and NE 2nd Pl. 3. Stormwater is conveyed south across NE 2nd Pl via a 12-inch diameter polyethylene pipe system for approximately 43 feet before reaching an open ditch channel. 4. Stormwater continues to flow south along 158th Ave SE through the open ditch channel for approximately 46 feet before reaching a 12-inch diameter corrugated metal pipe (CMP). 5. Stormwater is conveyed approximately 70 feet via the 12-inch diameter corrugated metal pipe system before transitioning to a 12-inch diameter polyethylene system. 6. The stormwater continues to be conveyed south via the 12-inch diameter polyethylene pipe system for approximately 336 feet before reaching a catch basin and transitioning to a 16-inch diameter ductile iron pipe. 7. Stormwater is conveyed along 158th Ave SE via the 16-inch diameter ductile iron pipe for approximately 9 feet before entering an open ditch system. 8. Stormwater flows through the open ditch system for approximately 24-feet, passing the ¼-mile mark downstream of the project site before entering a 12-inch concrete driveway culvert. 9. From here the stormwater continues via piped and open ditch systems until approximately 1 mile from the site where it discharges at a discharge point and flows into the Cedar River. The Cedar River ultimately discharges to Lake Washington. Task 5 – Mitigation of Existing or Potential Problems During the desk investigation and field investigation May 7th, 2024 there were no signs of erosion or overtopping of the downstream drainage system. At this time, the existing downstream drainage course appears to have adequate capacity to convey the proposed flows from the project. Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 LPD Engineering, PLLC Page 9 Renton Fire Station #16 Technical Information Report, November 12, 2024 SECTION 4 – FLOW CONTROL, LOW IMPACT DEVELOPMENT (LID) AND WATER QUALITY FACILITY ANALYSIS AND DESIGN Exiting Hydrology Please refer to Section 1 – Project Overview and Section 3 – Offsite 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 of this report for the full description of the proposed site hydrology. Performance Standards Please refer to Section 2 - Conditions and Requirements Summary, and the On-Site BMPs, Flow Control System, and Water Quality sections of this report for a description of the required standards applicable to this report. On-Site BMPs Per Core Requirement #9, the improvements in TDA 1 result in more than 2,000 SF of new plus replaced impervious surfaces, therefore an evaluation of BMP feasibility for all target surfaces is required. Per section 1.2.9.2 of the RSWDM, the project improvements will be subject to Large Lot BMP Requirements since the project site is larger than 22,000 SF. Due to the fill and glacial till found on the project site, there is no suitable stormwater infiltration receptor for infiltration BMPs. For these reasons, the LID performance standard cannot be achieved. Below is an evaluation of BMP feasibility for the site and frontage improvements. As previously mentioned, the proposed project improvements in TDA 2 result in less than 2,000 SF of new plus replaced impervious surface, therefore an evaluation of BMP feasibility for all target surfaces is not required. TDA 1 BMP Evaluation per Appendix C of the RSWDM: 1. Full Dispersion: Full Dispersion is infeasible, per section C.2.1.1, for all surfaces due to a lack of native vegetation. 2. Full Infiltration of Roof Runoff: As mentioned previously in the Existing Conditions Section of this Report, per the geotechnical evaluation by Geoengineers, the site soils are not suitable for infiltration. 3. Since the target impervious surfaces could not be mitigated by Requirements 1 and 2 above, the following has been reviewed and implemented where feasible: • Full Infiltration: Full infiltration of runoff from target surfaces is not feasible. As stated above: the on-site soils are not suitable for infiltration. • Limited Infiltration: As stated above: the on-site soils are not suitable for infiltration. Therefore, limited infiltration is considered infeasible. • Bioretention: Per Section C.2.6, a bioretention facilities without underdrains are considered infeasible, per Criteria #20 a vertical separation of 3 feet to the impervious layer cannot be achieved below the bioretention for areas that meet or exceed 5000 SF of PGIS. As stated above: the on-site soils are not suitable for infiltration. Per Section C.2.6.1.5 underdrains are not permitted by the City of Renton to meet Core Requirement #9. Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 LPD Engineering, PLLC Page 10 Renton Fire Station #16 Technical Information Report, November 12, 2024 • Permeable Pavement: Per section C.2.7 Criteria #24, the use of permeable is in-feasible because as mentioned previously in the Existing Conditions Section of this report, the geotechnical evaluation indicated that the infiltration rate is less than 0.3 inches per hour. Additionally, as mentioned previously in the Existing Conditions Section of this report, there is anticipated to be seasonally perched ground water present at the site above the impermeable dense to very dense glacial soils. 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. Flow Control System TDA 1 is required to meet the Flow Control Duration Standard Matching Forested Site Conditions, for which the project developed discharge durations shall not exceed predeveloped durations for the range of predeveloped discharge rates from 50% of the 2-year peak flow up to the full 50-year peak flow. Developed peak discharge rates shall not exceed predeveloped peak discharge rates for the 2-year and 10-year return periods. Per the RSWDM forested site conditions as the predeveloped condition. Per the RSWDM, flow control facilities must mitigate the runoff from the target surfaces which include new and replaced impervious surfaces that are not fully dispersed and new pervious surfaces that are not fully dispersed. The proposed project improvements in TDA 2 result in less than 5,000 SF of new plus replaced impervious surface AND less than ¾ acres of new pervious surface will be added. Therefore, the proposed improvements in TDA 2 meet the criteria for the Basic Exemption and flow control is not required. Refer to Figure 6 – Proposed Conditions for the delineation between the threshold discharge areas. Per RSWDM Chapter 1 the definition of new pervious surface includes the conversion of a native vegetated surface or other nonnative pervious surface to non-native pervious surface (e.g. conversion of forest or meadow to pasture land, grass land, cultivated land, lawn, landscaping, bare soils, etc.), or any alteration of existing non-native pervious surface that significantly increases surface and storm water runoff (e.g., conversion of pasture land, grass land, or cultivated land to lawn, landscaping, or bare soil; or alteration of soil characteristics). The existing site includes areas of landscape and lawn. The proposed landscape improvements will also include landscape and lawn areas. Therefore, there will be no modification of runoff characteristics from the pervious areas and these areas are not included as target surface areas. Per RSWDM Chapter 1 definition, replaced impervious surface “does not include the removal of pavement material through grinding or other surface modification unless the entire layer of PCC or AC is removed”. Therefore, the areas of proposed grind and overlay improvements included in both frontages for TDA 1 on SE 128th St, for TDA 2 on 158th Ave SE and for the offsite improvements along 158th Ave SE are not included as replaced impervious surface. Additionally, per the RSWDM Chapter 1 definition for replaced impervious surface excludes impervious surface removed for the sole purpose of installing utilities. Therefore, the offsite improvements for the proposed sewer and water connections along 158th Ave SE are not counted as replaced impervious surface. As shown in Figure 6 – Proposed Conditions, the total new and replaced impervious area for TDA 1 is 80,924 SF (1.86 acres). As discussed in the On-site BMPs Section above, full dispersion for these surfaces is infeasible. Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 LPD Engineering, PLLC Page 11 Renton Fire Station #16 Technical Information Report, November 12, 2024 Due to the site elevations, some areas of impervious surface were unable to be routed to detention. These areas include the northeastern area of the right-of-way frontage improvements on SE 128th St and northeastern driveway access, which total 3,993 SF (0.092 acres) of target surface area. In lieu of mitigating these areas 4,013 SF (0.092 acres) of the existing roadway along SE 128th will be collected and routed to the proposed detention system as compensatory area, shown in Figure 7 – Proposed Modeled Conditions. The flow control for TDA 1 is provided by a StormTech SC-740 Chamber System and a Detention Vault, with associated flow control structures. Refer to Figure 7 – Proposed Modeled Conditions which shows the contributing areas to each of the detention facilities. The Western Washington Hydrology Model 2012 (WWHM) was used to model the detention facilities for the site. Illustration 1 below shows the routing of the facilities in the model for each detention facility. This model demonstrates that the release rates from the site are less than the allowable release rates required, see Table 1 below for detention facility details. See Appendix B for the WHMM report for each of the detention facilities. The result of the WWHM Model was a 48 Chamber SC-740 StormTech System and 146 feet by 40 feet by 7 feet deep vault. Further details of the detention requirements are listed in Table 1. Table 1 – Detention Facility Details StormTech Chamber Detention Detention Vault Dimensions 70’ x 30’ x 3.5’ 146’ x 40’ x 7’ Storage Volume at Riser Crest (cu ft) 4,158 34,979 Riser Height (ft) Riser Diameter (in) 3 12 6 12 Bottom Orifice Diameter (in) 1.0 1.2 2nd Orifice Diameter (in) 2nd Orifice Height (ft) 2.4 2.2 1.4 3.5 3rd Orifice Diameter (in) 3rd Orifice Height (ft) N/A N/A N/A N/A Notch Width (in) Notch Height (ft) N/A N/A N/A N/A Illustration 1 – Combined Outflow Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 LPD Engineering, PLLC Page 12 Renton Fire Station #16 Technical Information Report, November 12, 2024 Water Quality System Per Core Requirement #8, the proposed project improvements in TDA 1 result in more than 5,000 SF of new plus replaced pollution-generating impervious surface (PGIS), and therefore will require water quality treatment. As Fire Stations are considered a commercial land use, Enhanced Basic Water Quality Treatment is required. The proposed project improvements in TDA 2 result in less than 5,000 SF of new plus replaced pollution-generating impervious surface (PGIS) AND less than ¾ acre of new pollution-generating pervious surface. Per the RSWDM Exemptions from Core Requirement #8, this area meets Exemption 1 Surface Area and therefore water quality treatment for TDA 2 is not be required. Water quality treatment will be required for 48,392 SF (1.11 acres) of pollution-generating impervious surface which include the proposed concrete driveways, parking lot and parking areas. Due to the site elevations, certain areas of pollution-generating impervious surface were unable to be routed to water quality treatment. These areas include the northeastern area of the right-of-way frontage improvements pavement along SE 128th St and northeastern driveway access, which total 2,204 SF (0.051 acres) of PGIS surfaces. In lieu of treating these areas, 4,013 SF (0.092 acres) of the existing roadway along SE 128th will be treated by the northern water quality basin #3 shown in Figure 7 – Proposed Modeled Conditions. Water quality treatment will be provided by three Modular Wetland Systems (MWS), which have General Use Level Designation (GULD) approval by Ecology for enhanced treatment. This approval is provided in Appendix B for reference. The water quality facilities will be located upstream of the detention systems, per section 6.2.1 of the 2022 RSWDM, the water quality design flow rate will be the flow rate at or below which 91% of the total runoff volume will be treated. The WWHM output for the water quality design flow rate for each facility will be provided at Permit Submittal. Refer to Figure 7 – Proposed Modeled Conditions for the proposed location of the three water quality basins. Sizing of the Modular Wetland Systems will be conducted by Contech Engineered Solutions and provided at Permit Submittal. SECTION 5 – CONVEYANCE SYSTEMS ANALYSIS AND DESIGN An analysis of the onsite conveyance system will be performed at Permit Submittal per section 1.2.4 of the 2022 RSWDM. The new pipes and culverts will be designed to accommodate the 25-year peak flow from the tributary area. For conservative pipe sizing the 100-year peak flow will also be included in the backwater analysis. SECTION 6 – SPECIAL REPORTS AND STUDIES A Geotechnical Report has been prepared by GeoEngineers, Inc., dated August 5th, 2022. This report is provided in Appendix F. Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 LPD Engineering, PLLC Page 13 Renton Fire Station #16 Technical Information Report, November 12, 2024 SECTION 7 – OTHER PERMITS Coverage under the Construction Stormwater General Permit through the Department of Ecology will be required for the project because it disturbs over one (1) acre of land area. The NOI and public noticing required for this permit will be completed later in the design process, prior to construction. SECTION 8 – CSWPPP ANALYSIS AND DESIGN A Construction stormwater pollution prevention plan (CSWPP) including a Stormwater Pollution Prevention and Spill Control Plan (SWPPS) and a Temporary Erosion and Sediment Control (TESC) plan will be prepared and provided at Permit Submittal. The TESC plan includes temporary sediment settling tanks, sized using the methodology from the 2022 RSWDM. A copy of the Sediment Facility Sizing Calculations worksheet and the associated output from MGS Flood used for the sediment tank sizing are included in Appendix B. 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 any demolition or construction. SECTION 9 – BOND QUANTITIES, FACILITY SUMMARIES, AND DECLARATION OF COVENANT A Bond Quantities Worksheet is not required, as the owner is the Renton Regional Fire Authority, which is a public agency; no bonding is required. A Drainage Declaration of Covenant will be provided at Permit Submittal in Appendix E. SECTION 10 – OPERATIONS AND MAINTENANCE MANUAL The Operations and Maintenance Manual will be prepared and provided in Appendix D of this report at Permit Submittal. This will include maintenance recommendations associated with the conveyance pipes, catch basins, flow control structures, StormTech chamber detention facility, detention vault, and the Modular Wetland System (water quality facility). Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 LPD Engineering, PLLC Page 14 Renton Fire Station #16 Technical Information Report, November 12, 2024 FIGURES Figure 1: TIR Worksheet Figure 2: Vicinity Map Figure 3: Downstream Drainage Map 1 Figure 4: Downstream Drainage Map 2 Figure 5: Soils Map Figure 6: Proposed Conditions Figure 7: Proposed Modeled Conditions Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 CITY OF RENTON SURFACE WATER DESIGN MANUAL 2022 City of Renton Surface Water Design Manual 6/22/2022 8-A-1 REFERENCE 8-A TECHNICAL INFORMATION REPORT (TIR) WORKSHEET Part 1 PROJECT OWNER AND PROJECT ENGINEER Part 2 PROJECT LOCATION AND DESCRIPTION Project Owner _____________________________ Phone ___________________________________ Address __________________________________ _________________________________________ Project Engineer ___________________________ Company _________________________________ Phone ___________________________________ Project Name __________________________ CED Permit # ________________________ Location Township ________________ Range __________________ Section _________________ Site Address __________________________ _____________________________________ Part 3 TYPE OF PERMIT APPLICATION Part 4 OTHER REVIEWS AND PERMITS Land Use (e.g., Subdivision / Short Subd.) Building (e.g., M/F / Commercial / SFR) Grading Right-of-Way Use Other _______________________ DFW HPA COE 404 DOE Dam Safety FEMA Floodplain COE Wetlands Other ________ Shoreline Management Structural Rockery/Vault/_____ ESA Section 7 Part 5 PLAN AND REPORT INFORMATION Technical Information Report Site Improvement Plan (Engr. Plans) Type of Drainage Review (check one): Date (include revision dates): Date of Final: Full Targeted Simplified Large Project Directed __________________ __________________ __________________ Plan Type (check one): Date (include revision dates): Date of Final: Full Modified Simplified __________________ __________________ __________________ TBD Marc Servizi, PE LPD Engineering PLLC (206) 725 - 1211 Renton Regional Fire Station #16 Renton, WA 98059 X X X X X X 15815 SE 128th St 18002 108th Ave SE Renton, WA 98055 23 North 5 East 14 (425) 276-9500 Renton Regional Fire Authority Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 REFERENCE 8: PLAN REVIEW FORMS AND WORKSHEET TECHNICAL INFORMATION REPORT (TIR) WORKSHEET 6/22/2022 2022 City of Renton Surface Water Design Manual 8-A-2 Part 6 SWDM ADJUSTMENT APPROVALS Type (circle one): Standard / Blanket Description: (include conditions in TIR Section 2) ____________________________________________________________________________________ ____________________________________________________________________________________ ____________________________________________________________________________________ Approved Adjustment No. ______________________ Date of Approval: _______________________ Part 7 MONITORING REQUIREMENTS Monitoring Required: Yes / No Start Date: _______________________ Completion Date: _______________________ Describe: _________________________________ _________________________________________ _________________________________________ Re: SWDM Adjustment No. ________________ Part 8 SITE COMMUNITY AND DRAINAGE BASIN Community Plan: ____________________________________________________________________ Special District Overlays: ______________________________________________________________ Drainage Basin: _____________________________________________________________________ Stormwater Requirements: _____________________________________________________________ Part 9 ONSITE AND ADJACENT SENSITIVE AREAS River/Stream ________________________ Lake ______________________________ Wetlands ____________________________ Closed Depression ____________________ Floodplain ___________________________ Other _______________________________ _______________________________ Steep Slope __________________________ Erosion Hazard _______________________ Landslide Hazard ______________________ Coal Mine Hazard ______________________ Seismic Hazard _______________________ Habitat Protection ______________________ _____________________________________ N/A N/A May Creek Drainage Basin N/A None planned at this time. Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 REFERENCE 8-A: TECHNICAL INFORMATION REPORT (TIR) WORKSHEET TECHNICAL INFORMATION REPORT (TIR) WORKSHEET 2022 City of Renton Surface Water Design Manual 6/22/2022 Ref 8-A-3 Part 10 SOILS Soil Type ______________________ ______________________ ______________________ ______________________ Slopes ________________________ ________________________ ________________________ ________________________ Erosion Potential _________________________ _________________________ _________________________ _________________________ High Groundwater Table (within 5 feet) Other ________________________________ Sole Source Aquifer Seeps/Springs Additional Sheets Attached Part 11 DRAINAGE DESIGN LIMITATIONS REFERENCE Core 2 – Offsite Analysis_________________ Sensitive/Critical Areas__________________ SEPA________________________________ LID Infeasibility________________________ Other________________________________ _____________________________________ LIMITATION / SITE CONSTRAINT _______________________________________ _______________________________________ _______________________________________ _______________________________________ _______________________________________ _______________________________________ Additional Sheets Attached Part 12 TIR SUMMARY SHEET (provide one TIR Summary Sheet per Threshold Discharge Area) Threshold Discharge Area: (name or description) Core Requirements (all 9 apply): Discharge at Natural Location Number of Natural Discharge Locations: Offsite Analysis Level: 1 / 2 / 3 dated:__________________ Flow Control (include facility summary sheet) Standard: _______________________________ or Exemption Number: ____________ Conveyance System Spill containment located at: _____________________________ Erosion and Sediment Control / Construction Stormwater Pollution Prevention CSWPP/CESCL/ESC Site Supervisor: _____________________ Contact Phone: _________________________ After Hours Phone: _________________________ Maintenance and Operation Responsibility (circle one): Private / Public If Private, Maintenance Log Required: Yes / No Financial Guarantees and Liability Provided: Yes / No North Basin, South Basin 2 TBD Glacial Till 5/7/2024 Soil Type, High Groundwater X X 8% to 15%low to moderate Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 REFERENCE 8: PLAN REVIEW FORMS AND WORKSHEET TECHNICAL INFORMATION REPORT (TIR) WORKSHEET 6/22/2022 2022 City of Renton Surface Water Design Manual 8-A-4 Part 12 TIR SUMMARY SHEET (provide one TIR Summary Sheet per Threshold Discharge Area) Water Quality (include facility summary sheet) Type (circle one): Basic / Sens. Lake / Enhanced Basic / Bog or Exemption No. _______________________ On-site BMPs Describe: Special Requirements (as applicable): Area Specific Drainage Requirements Type: SDO / MDP / BP / Shared Fac. / None Name: ________________________ Floodplain/Floodway Delineation Type (circle one): Major / Minor / Exemption / None 100-year Base Flood Elevation (or range): _______________ Datum: Flood Protection Facilities Describe: Source Control (commercial / industrial land use) Describe land use: Describe any structural controls: Oil Control High-Use Site: Yes / No Treatment BMP: _________________________________ Maintenance Agreement: Yes / No with whom? _____________________________________ Other Drainage Structures Describe: Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 REFERENCE 8-A: TECHNICAL INFORMATION REPORT (TIR) WORKSHEET TECHNICAL INFORMATION REPORT (TIR) WORKSHEET 2022 City of Renton Surface Water Design Manual 6/22/2022 Ref 8-A-5 Part 13 EROSION AND SEDIMENT CONTROL REQUIREMENTS MINIMUM ESC REQUIREMENTS DURING CONSTRUCTION Clearing Limits Cover Measures Perimeter Protection Traffic Area Stabilization Sediment Retention Surface Water Collection Dewatering Control Dust Control Flow Control Control Pollutants Protect Existing and Proposed BMPs/Facilities Maintain Protective BMPs / Manage Project MINIMUM ESC REQUIREMENTS AFTER CONSTRUCTION Stabilize exposed surfaces Remove and restore Temporary ESC Facilities Clean and remove all silt and debris, ensure operation of Permanent BMPs/Facilities, restore operation of BMPs/Facilities as necessary Flag limits of sensitive areas and open space preservation areas Other _______________________ Part 14 STORMWATER FACILITY DESCRIPTIONS (Note: Include Facility Summary and Sketch) Flow Control Description Water Quality Description On-site BMPs Description Detention Infiltration Regional Facility Shared Facility Other _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ Vegetated Flowpath Wetpool Filtration Oil Control Spill Control Other _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ Full Dispersion Full Infiltration Limited Infiltration Rain Gardens Bioretention Permeable Pavement Basic Dispersion Soil Amendment Perforated Pipe Connection Other _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ X X X X X X X X X X X X X X X X X X StormTech System and Detention Vault Modular Wetland System Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 REFERENCE 8: PLAN REVIEW FORMS AND WORKSHEET TECHNICAL INFORMATION REPORT (TIR) WORKSHEET 6/22/2022 2022 City of Renton Surface Water Design Manual 8-A-6 Part 15 EASEMENTS/TRACTS Part 16 STRUCTURAL ANALYSIS Drainage Easement Covenant Native Growth Protection Covenant Tract Other ____________________________ Cast in Place Vault Retaining Wall Rockery > 4′ High Structural on Steep Slope Other _______________________________ Part 17 SIGNATURE OF PROFESSIONAL ENGINEER I, or a civil engineer under my supervision, have visited the site. Actual site conditions as observed were incorporated into this worksheet and the attached Technical Information Report. To the best of my knowledge the information provided here is accurate. ____________________________________________________________________________________ Signed/Date X X X Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 RENTON FIRE STATION 16 2VICINITY MAP 1932 First Ave Suite 500 Seattle, WA 98101 p. 206.725.1211 f. 206.973.5344 www.lpdengineering.comengineering pllc SE 132ND PL 15 6 T H A V E S E SE 133RD ST 15 6 T H A V E S E SE 128TH STSE 128TH ST 15 6 T H A V E S E SE 132ND ST 15 8 T H A V E S E SE 130TH ST SE 131ST ST SE 132ND ST SE 127TH ST 160 T H A V E S E 16 0 T H A V E S E Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 2024 LPD Engineering PLLC©1932 First Ave Suite 500 Seattle, WA 98101 p. 206.725.1211 f. 206.973.5344 www.lpdengineering.comengineering pllc RENTON FIRE STATION 16 3DOWNSTREAM DRAINAGE MAP 1 Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 1932 First Ave, Suite 500, Seattle, WA 98101 p. 206.725.1211 f. 206.973.5344 www.lpdengineering.comengineering pllc 2024 LPD Engineering PLLC© RENTON FIRE STATION 16 4DOWNSTREAM DRAINAGE MAP 2 Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 MAP UNIT SYMBOL KING COUNTY AREA, WASHINGTON (WA663) MAP UNIT NAME engineering pllc 7936 Seward Park Ave S, Seattle, WA 98118 p. 206.725.1211 f. 206.973.5344 www.lpdengineering.com RENTON FIRE STATION 16 5SOILS MAP SE 128TH ST AgC Alderwood Gravelly Sandy Loam, 8% to 15% slopes Bh Bellingham silt loam Sk Seattle muck W Water Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 T 2024 LPD Engineering PLLC©1932 First Ave Suite 500 Seattle, WA 98101 p. 206.725.1211 f. 206.973.5344 www.lpdengineering.comengineering pllc RENTON FIRE STATION 16 6PROPOSED CONDITIONS Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 T 2024 LPD Engineering PLLC©1932 First Ave Suite 500 Seattle, WA 98101 p. 206.725.1211 f. 206.973.5344 www.lpdengineering.comengineering pllc RENTON FIRE STATION 16 7PROPOSED MODELED CONDITIONS Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 LPD Engineering, PLLC Page 15 Renton Fire Station #16 Technical Information Report, November 12, 2024 APPENDIX A Design Drawings Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 LPD Engineering, PLLC Page 16 Renton Fire Station #16 Technical Information Report, November 12, 2024 APPENDIX B Design Calculations and Supporting Information Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 Sediment Facility Sizing Calculations Per the City of Renton Surface Water Design Manual 2022 Section D.2.1.5.1 Project Name: Renton Regional Fire Station 16 Required Sediment Facility Surface Area (SA): SA =2*Q/Vsed Where: Q = 2-year developed flow rate from WWHM Vsed = Settling Velocity (0.00096 ft/sec) Calculation: multiplier = 2 Q = 1.0670 cfs Vsed = 0.00096 fps Required SA = 2222.9 square feet Equivalent Sediment Trap Volume: Length of Top Surface Area = 48 feet Width of Top Surface Area = 47 feet Surface Area Provided = 2256 square feet Side Slope = 3 (H:1V) Total Depth of Sediment Trap = 3.5 feet Bottom Length of Sediment Trap = 27 feet Bottom Width of Sediment Trap = 26 feet Total pond Volume = 5176.5 cubic feet 38720.22 gallons To determine the minimum sediment trap volume, an equivalent sediment trap was sized based upon the required surface area. Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 WWHM2012 PROJECT REPORT – Sediment Settling Tank ___________________________________________________________________ Project Name: TESC Site Name: Renton FS 16 Site Address: City : Renton Report Date: 11/11/2024 Gage : Seatac Data Start : 1948/10/01 Data End : 2009/09/30 Precip Scale: 1.17 Version Date: 2020/10/14 Version : 4.2.16 ___________________________________________________________________ Low Flow Threshold for POC 1 : 50 Percent of the 2 Year ___________________________________________________________________ High Flow Threshold for POC 1: 50 year ___________________________________________________________________ PREDEVELOPED LAND USE Name : Basin 1 Bypass: No GroundWater: No Pervious Land Use acre C, Lawn, Flat 1.77 Pervious Total 1.77 Impervious Land Use acre SIDEWALKS FLAT 1.9 Impervious Total 1.9 Basin Total 3.67 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ MITIGATED LAND USE Name : Basin 1 Bypass: No GroundWater: No Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 Pervious Land Use acre C, Lawn, Flat 1.77 Pervious Total 1.77 Impervious Land Use acre SIDEWALKS FLAT 1.9 Impervious Total 1.9 Basin Total 3.67 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ ___________________________________________________________________ ANALYSIS RESULTS Stream Protection Duration ___________________________________________________________________ Predeveloped Landuse Totals for POC #1 Total Pervious Area:1.77 Total Impervious Area:1.9 ___________________________________________________________________ Mitigated Landuse Totals for POC #1 Total Pervious Area:1.77 Total Impervious Area:1.9 ___________________________________________________________________ Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 1.06734 5 year 1.423028 10 year 1.674942 25 year 2.01256 50 year 2.278473 100 year 2.557031 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 1.06734 5 year 1.423028 10 year 1.674942 25 year 2.01256 50 year 2.278473 100 year 2.557031 Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 ___________________________________________________________________ Stream Protection Duration Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1949 1.546 1.546 1950 1.389 1.389 1951 0.944 0.944 1952 0.645 0.645 1953 0.720 0.720 1954 0.888 0.888 1955 0.966 0.966 1956 0.930 0.930 1957 1.166 1.166 1958 0.832 0.832 1959 0.759 0.759 1960 0.969 0.969 1961 0.961 0.961 1962 0.725 0.725 1963 0.966 0.966 1964 0.857 0.857 1965 1.203 1.203 1966 0.733 0.733 1967 1.382 1.382 1968 1.498 1.498 1969 1.131 1.131 1970 1.014 1.014 1971 1.188 1.188 1972 1.435 1.435 1973 0.619 0.619 1974 1.145 1.145 1975 1.173 1.173 1976 0.868 0.868 1977 0.909 0.909 1978 1.034 1.034 1979 1.350 1.350 1980 1.608 1.608 1981 1.110 1.110 1982 1.702 1.702 1983 1.179 1.179 1984 0.797 0.797 1985 1.100 1.100 1986 0.933 0.933 1987 1.371 1.371 1988 0.728 0.728 1989 0.989 0.989 1990 2.414 2.414 1991 1.858 1.858 1992 0.790 0.790 1993 0.658 0.658 1994 0.631 0.631 1995 0.930 0.930 1996 1.167 1.167 1997 1.098 1.098 1998 0.960 0.960 1999 2.324 2.324 2000 1.088 1.088 Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 2001 1.069 1.069 2002 1.502 1.502 2003 1.212 1.212 2004 2.139 2.139 2005 0.951 0.951 2006 0.874 0.874 2007 2.185 2.185 2008 1.818 1.818 2009 1.170 1.170 ___________________________________________________________________ Stream Protection Duration Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 2.4137 2.4137 2 2.3243 2.3243 3 2.1854 2.1854 4 2.1389 2.1389 5 1.8578 1.8578 6 1.8177 1.8177 7 1.7019 1.7019 8 1.6075 1.6075 9 1.5462 1.5462 10 1.5025 1.5025 11 1.4979 1.4979 12 1.4353 1.4353 13 1.3894 1.3894 14 1.3822 1.3822 15 1.3712 1.3712 16 1.3499 1.3499 17 1.2118 1.2118 18 1.2027 1.2027 19 1.1878 1.1878 20 1.1786 1.1786 21 1.1729 1.1729 22 1.1703 1.1703 23 1.1670 1.1670 24 1.1661 1.1661 25 1.1452 1.1452 26 1.1310 1.1310 27 1.1099 1.1099 28 1.0998 1.0998 29 1.0979 1.0979 30 1.0885 1.0885 31 1.0693 1.0693 32 1.0343 1.0343 33 1.0144 1.0144 34 0.9886 0.9886 35 0.9688 0.9688 36 0.9660 0.9660 37 0.9660 0.9660 38 0.9614 0.9614 39 0.9601 0.9601 40 0.9513 0.9513 41 0.9445 0.9445 42 0.9333 0.9333 43 0.9300 0.9300 Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 44 0.9296 0.9296 45 0.9092 0.9092 46 0.8876 0.8876 47 0.8737 0.8737 48 0.8683 0.8683 49 0.8567 0.8567 50 0.8315 0.8315 51 0.7969 0.7969 52 0.7900 0.7900 53 0.7591 0.7591 54 0.7330 0.7330 55 0.7277 0.7277 56 0.7247 0.7247 57 0.7199 0.7199 58 0.6579 0.6579 59 0.6446 0.6446 60 0.6313 0.6313 61 0.6191 0.6191 ___________________________________________________________________ Stream Protection Duration POC #1 The Facility PASSED The Facility PASSED. Flow(cfs) Predev Mit Percentage Pass/Fail 0.5337 1351 1351 100 Pass 0.5513 1211 1211 100 Pass 0.5689 1092 1092 100 Pass 0.5865 978 978 100 Pass 0.6042 880 880 100 Pass 0.6218 810 810 100 Pass 0.6394 742 742 100 Pass 0.6570 671 671 100 Pass 0.6747 617 617 100 Pass 0.6923 560 560 100 Pass 0.7099 520 520 100 Pass 0.7275 476 476 100 Pass 0.7452 442 442 100 Pass 0.7628 404 404 100 Pass 0.7804 381 381 100 Pass 0.7980 351 351 100 Pass 0.8157 332 332 100 Pass 0.8333 308 308 100 Pass 0.8509 288 288 100 Pass 0.8685 274 274 100 Pass 0.8862 255 255 100 Pass 0.9038 236 236 100 Pass 0.9214 217 217 100 Pass 0.9390 201 201 100 Pass 0.9567 186 186 100 Pass 0.9743 169 169 100 Pass 0.9919 161 161 100 Pass 1.0095 151 151 100 Pass 1.0271 143 143 100 Pass 1.0448 134 134 100 Pass Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 1.0624 126 126 100 Pass 1.0800 117 117 100 Pass 1.0976 112 112 100 Pass 1.1153 107 107 100 Pass 1.1329 102 102 100 Pass 1.1505 97 97 100 Pass 1.1681 86 86 100 Pass 1.1858 82 82 100 Pass 1.2034 77 77 100 Pass 1.2210 73 73 100 Pass 1.2386 71 71 100 Pass 1.2563 69 69 100 Pass 1.2739 67 67 100 Pass 1.2915 66 66 100 Pass 1.3091 64 64 100 Pass 1.3268 59 59 100 Pass 1.3444 56 56 100 Pass 1.3620 53 53 100 Pass 1.3796 51 51 100 Pass 1.3973 47 47 100 Pass 1.4149 42 42 100 Pass 1.4325 40 40 100 Pass 1.4501 37 37 100 Pass 1.4678 34 34 100 Pass 1.4854 33 33 100 Pass 1.5030 31 31 100 Pass 1.5206 29 29 100 Pass 1.5383 29 29 100 Pass 1.5559 27 27 100 Pass 1.5735 25 25 100 Pass 1.5911 23 23 100 Pass 1.6088 21 21 100 Pass 1.6264 21 21 100 Pass 1.6440 21 21 100 Pass 1.6616 19 19 100 Pass 1.6792 18 18 100 Pass 1.6969 17 17 100 Pass 1.7145 15 15 100 Pass 1.7321 14 14 100 Pass 1.7497 13 13 100 Pass 1.7674 12 12 100 Pass 1.7850 12 12 100 Pass 1.8026 11 11 100 Pass 1.8202 10 10 100 Pass 1.8379 10 10 100 Pass 1.8555 9 9 100 Pass 1.8731 8 8 100 Pass 1.8907 7 7 100 Pass 1.9084 7 7 100 Pass 1.9260 7 7 100 Pass 1.9436 7 7 100 Pass 1.9612 7 7 100 Pass 1.9789 7 7 100 Pass 1.9965 7 7 100 Pass 2.0141 7 7 100 Pass 2.0317 6 6 100 Pass 2.0494 6 6 100 Pass Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 2.0670 5 5 100 Pass 2.0846 5 5 100 Pass 2.1022 5 5 100 Pass 2.1199 5 5 100 Pass 2.1375 5 5 100 Pass 2.1551 3 3 100 Pass 2.1727 3 3 100 Pass 2.1904 2 2 100 Pass 2.2080 2 2 100 Pass 2.2256 2 2 100 Pass 2.2432 2 2 100 Pass 2.2608 2 2 100 Pass 2.2785 2 2 100 Pass _____________________________________________________ ___________________________________________________________________ Water Quality BMP Flow and Volume for POC #1 On-line facility volume: 0 acre-feet On-line facility target flow: 0 cfs. Adjusted for 15 min: 0 cfs. Off-line facility target flow: 0 cfs. Adjusted for 15 min: 0 cfs. ___________________________________________________________________ LID Report LID Technique Used for Total Volume Volume Infiltration Cumulative Percent Water Quality Percent Comment Treatment? Needs Through Volume Volume Volume Water Quality Treatment Facility (ac-ft.) Infiltration Infiltrated Treated (ac-ft) (ac-ft) Credit Total Volume Infiltrated 0.00 0.00 0.00 0.00 0.00 0% No Treat. Credit Compliance with LID Standard 8 Duration Analysis Result = Passed ___________________________________________________________________ Perlnd and Implnd Changes No changes have been made. ___________________________________________________________________ This program and accompanying documentation are provided 'as-is' without warranty of any kind. The entire risk regarding the performance and results of this program is assumed by End User. Clear Creek Solutions Inc. and the governmental licensee or sublicensees disclaim all warranties, either expressed or implied, including but not limited to implied warranties of program and accompanying documentation. In no event shall Clear Creek Solutions Inc. be liable for any damages whatsoever (including without limitation to damages for loss of business profits, loss of business information, business interruption, and the like) arising out of the use of, or inability to use this program even if Clear Creek Solutions Inc. or their authorized representatives have been advised of the possibility of such damages. Software Copyright © by : Clear Creek Solutions, Inc. 2005-2024; All Rights Reserved. Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 Project: Chamber Model - SC-740 Units -Imperial - Number of Chambers - 48 Voids in the stone (porosity) - 40 % Base of Stone Elevation - 0.00 ft Amount of Stone Above Chambers - 6 in Amount of Stone Below Chambers - 6 in Area of system - 2026 sf Min. Area - Height of System Incremental Single Chamber Incremental Total Chamber Incremental Stone Incremental Ch & St Cumulative Chamber Elevation (inches)(cubic feet)(cubic feet)(cubic feet)(cubic feet)(cubic feet)(feet) 42 0.00 0.00 67.53 67.53 4159.64 3.50 41 0.00 0.00 67.53 67.53 4092.11 3.42 40 0.00 0.00 67.53 67.53 4024.58 3.33 39 0.00 0.00 67.53 67.53 3957.05 3.25 38 0.00 0.00 67.53 67.53 3889.52 3.17 37 0.00 0.00 67.53 67.53 3821.99 3.08 36 0.05 2.64 66.47 69.11 3754.46 3.00 35 0.16 7.82 64.40 72.22 3685.35 2.92 34 0.28 13.53 62.12 75.65 3613.13 2.83 33 0.60 28.99 55.93 84.92 3537.48 2.75 32 0.80 38.48 52.14 90.62 3452.55 2.67 31 0.95 45.63 49.28 94.91 3361.93 2.58 30 1.07 51.58 46.90 98.48 3267.03 2.50 29 1.18 56.66 44.86 101.53 3168.55 2.42 28 1.27 60.75 43.23 103.98 3067.02 2.33 27 1.36 65.04 41.51 106.55 2963.04 2.25 26 1.45 69.80 39.61 109.41 2856.49 2.17 25 1.52 73.19 38.26 111.44 2747.08 2.08 24 1.58 75.95 37.15 113.10 2635.64 2.00 23 1.64 78.83 36.00 114.83 2522.53 1.92 22 1.70 81.58 34.90 116.48 2407.71 1.83 21 1.75 84.14 33.87 118.01 2291.23 1.75 20 1.80 86.54 32.92 119.45 2173.22 1.67 19 1.85 89.04 31.91 120.95 2053.77 1.58 18 1.89 90.87 31.18 122.05 1932.81 1.50 17 1.93 92.83 30.40 123.23 1810.76 1.42 16 1.97 94.80 29.61 124.41 1687.53 1.33 15 2.01 96.48 28.94 125.42 1563.12 1.25 14 2.04 98.16 28.27 126.43 1437.71 1.17 13 2.07 99.60 27.69 127.29 1311.28 1.08 12 2.10 101.04 27.12 128.15 1183.99 1.00 11 2.13 102.33 26.60 128.93 1055.84 0.92 10 2.15 103.39 26.18 129.56 926.91 0.83 9 2.18 104.50 25.73 130.23 797.35 0.75 8 2.20 105.52 25.32 130.84 667.12 0.67 7 2.21 105.95 25.15 131.10 536.28 0.58 6 0.00 0.00 67.53 67.53 405.18 0.50 5 0.00 0.00 67.53 67.53 337.65 0.42 4 0.00 0.00 67.53 67.53 270.12 0.33 3 0.00 0.00 67.53 67.53 202.59 0.25 2 0.00 0.00 67.53 67.53 135.06 0.17 1 0.00 0.00 67.53 67.53 67.53 0.08 Renton FS 16 1623 sf min. area StormTech SC-740 Cumulative Storage Volumes Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 WWHM2012 PROJECT REPORT – Combined Detention Outflow ___________________________________________________________________ Project Name: Det Sys Site Name: Renton FS 16 Site Address: City : Renton Report Date: 11/11/2024 Gage : Seatac Data Start : 1948/10/01 Data End : 2009/09/30 (adjusted) Precip Scale: 0.00 Version Date: 2020/10/14 Version : 4.2.16 ___________________________________________________________________ Low Flow Threshold for POC 1 : 50 Percent of the 2 Year ___________________________________________________________________ High Flow Threshold for POC 1: 50 year ___________________________________________________________________ PREDEVELOPED LAND USE Name : Vault Bypass: No GroundWater: No Pervious Land Use acre C, Forest, Flat 1.599 C, Lawn, Flat 1.074 Pervious Total 2.673 Impervious Land Use acre ROOF TOPS FLAT 0.067 Impervious Total 0.067 Basin Total 2.74 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ Name : StormTech Bypass: No GroundWater: No Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 Pervious Land Use acre C, Lawn, Flat .405 C, Forest, Flat .259 Pervious Total 0.664 Impervious Land Use acre Impervious Total 0 Basin Total 0.664 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ MITIGATED LAND USE Name : Vault Bypass: No GroundWater: No Pervious Land Use acre C, Lawn, Flat 1.074 Pervious Total 1.074 Impervious Land Use acre ROOF TOPS FLAT 0.067 SIDEWALKS FLAT 1.599 Impervious Total 1.666 Basin Total 2.74 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater Vault 1 Vault 1 ___________________________________________________________________ Name : Vault 1 Width : 40 ft. Length : 146 ft. Depth: 7 ft. Discharge Structure Riser Height: 6 ft. Riser Diameter: 12 in. Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 Orifice 1 Diameter: 1.2 in. Elevation: 0 ft. Orifice 2 Diameter: 1.4 in. Elevation: 3.5 ft. Element Flows To: Outlet 1 Outlet 2 ___________________________________________________________________ Vault Hydraulic Table Stage(feet) Area(ac.) Volume(ac-ft.) Discharge(cfs) Infilt(cfs) 0.0000 0.134 0.000 0.000 0.000 0.0778 0.134 0.010 0.010 0.000 0.1556 0.134 0.020 0.015 0.000 0.2333 0.134 0.031 0.018 0.000 0.3111 0.134 0.041 0.021 0.000 0.3889 0.134 0.052 0.024 0.000 0.4667 0.134 0.062 0.026 0.000 0.5444 0.134 0.073 0.028 0.000 0.6222 0.134 0.083 0.030 0.000 0.7000 0.134 0.093 0.032 0.000 0.7778 0.134 0.104 0.034 0.000 0.8556 0.134 0.114 0.036 0.000 0.9333 0.134 0.125 0.037 0.000 1.0111 0.134 0.135 0.039 0.000 1.0889 0.134 0.146 0.040 0.000 1.1667 0.134 0.156 0.042 0.000 1.2444 0.134 0.166 0.043 0.000 1.3222 0.134 0.177 0.044 0.000 1.4000 0.134 0.187 0.046 0.000 1.4778 0.134 0.198 0.047 0.000 1.5556 0.134 0.208 0.048 0.000 1.6333 0.134 0.219 0.049 0.000 1.7111 0.134 0.229 0.051 0.000 1.7889 0.134 0.239 0.052 0.000 1.8667 0.134 0.250 0.053 0.000 1.9444 0.134 0.260 0.054 0.000 2.0222 0.134 0.271 0.055 0.000 2.1000 0.134 0.281 0.056 0.000 2.1778 0.134 0.292 0.057 0.000 2.2556 0.134 0.302 0.058 0.000 2.3333 0.134 0.312 0.059 0.000 2.4111 0.134 0.323 0.060 0.000 2.4889 0.134 0.333 0.061 0.000 2.5667 0.134 0.344 0.062 0.000 2.6444 0.134 0.354 0.063 0.000 2.7222 0.134 0.365 0.064 0.000 2.8000 0.134 0.375 0.065 0.000 2.8778 0.134 0.385 0.066 0.000 2.9556 0.134 0.396 0.067 0.000 3.0333 0.134 0.406 0.068 0.000 3.1111 0.134 0.417 0.068 0.000 3.1889 0.134 0.427 0.069 0.000 3.2667 0.134 0.438 0.070 0.000 3.3444 0.134 0.448 0.071 0.000 3.4222 0.134 0.458 0.072 0.000 Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 3.5000 0.134 0.469 0.073 0.000 3.5778 0.134 0.479 0.088 0.000 3.6556 0.134 0.490 0.095 0.000 3.7333 0.134 0.500 0.101 0.000 3.8111 0.134 0.510 0.106 0.000 3.8889 0.134 0.521 0.110 0.000 3.9667 0.134 0.531 0.114 0.000 4.0444 0.134 0.542 0.117 0.000 4.1222 0.134 0.552 0.121 0.000 4.2000 0.134 0.563 0.124 0.000 4.2778 0.134 0.573 0.127 0.000 4.3556 0.134 0.583 0.130 0.000 4.4333 0.134 0.594 0.133 0.000 4.5111 0.134 0.604 0.136 0.000 4.5889 0.134 0.615 0.139 0.000 4.6667 0.134 0.625 0.141 0.000 4.7444 0.134 0.636 0.144 0.000 4.8222 0.134 0.646 0.147 0.000 4.9000 0.134 0.656 0.149 0.000 4.9778 0.134 0.667 0.151 0.000 5.0556 0.134 0.677 0.154 0.000 5.1333 0.134 0.688 0.156 0.000 5.2111 0.134 0.698 0.158 0.000 5.2889 0.134 0.709 0.161 0.000 5.3667 0.134 0.719 0.163 0.000 5.4444 0.134 0.729 0.165 0.000 5.5222 0.134 0.740 0.167 0.000 5.6000 0.134 0.750 0.169 0.000 5.6778 0.134 0.761 0.171 0.000 5.7556 0.134 0.771 0.173 0.000 5.8333 0.134 0.782 0.175 0.000 5.9111 0.134 0.792 0.177 0.000 5.9889 0.134 0.802 0.179 0.000 6.0667 0.134 0.813 0.363 0.000 6.1444 0.134 0.823 0.756 0.000 6.2222 0.134 0.834 1.231 0.000 6.3000 0.134 0.844 1.696 0.000 6.3778 0.134 0.855 2.068 0.000 6.4556 0.134 0.865 2.305 0.000 6.5333 0.134 0.875 2.492 0.000 6.6111 0.134 0.886 2.656 0.000 6.6889 0.134 0.896 2.810 0.000 6.7667 0.134 0.907 2.955 0.000 6.8444 0.134 0.917 3.093 0.000 6.9222 0.134 0.928 3.225 0.000 7.0000 0.134 0.938 3.352 0.000 7.0778 0.134 0.948 3.474 0.000 7.1556 0.000 0.000 3.592 0.000 ___________________________________________________________________ Name : StormTech Bypass: No GroundWater: No Pervious Land Use acre C, Lawn, Flat .405 Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 Pervious Total 0.405 Impervious Land Use acre SIDEWALKS FLAT 0.259 Impervious Total 0.259 Basin Total 0.664 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater SSD Table 1 SSD Table 1 ___________________________________________________________________ Name : SSD Table 1 Depth: 3.5 ft. Discharge Structure: 1 Riser Height: 3 ft. Riser Diameter: 12 in. Orifice 1 Diameter: 1 in. Elevation: 0 ft. Orifice 2 Diameter: 2.2 in. Elevation: 2.2 ft. Element Flows To: Outlet 1 Outlet 2 ___________________________________________________________________ SSD Table Hydraulic Table Stage Area Volume Outlet (feet) (ac.) (ac-ft.) Struct NotUsed NotUsed NotUsed NotUsed 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.083 0.047 0.002 0.008 0.000 0.000 0.000 0.000 0.167 0.147 0.003 0.011 0.000 0.000 0.000 0.000 0.250 0.247 0.005 0.014 0.000 0.000 0.000 0.000 0.333 0.347 0.006 0.016 0.000 0.000 0.000 0.000 0.417 0.447 0.008 0.018 0.000 0.000 0.000 0.000 0.500 0.547 0.009 0.019 0.000 0.000 0.000 0.000 0.583 0.647 0.012 0.021 0.000 0.000 0.000 0.000 0.667 0.747 0.015 0.022 0.000 0.000 0.000 0.000 0.750 0.847 0.018 0.024 0.000 0.000 0.000 0.000 0.833 0.947 0.021 0.025 0.000 0.000 0.000 0.000 0.917 1.047 0.024 0.026 0.000 0.000 0.000 0.000 1.000 1.147 0.027 0.027 0.000 0.000 0.000 0.000 1.083 1.247 0.030 0.028 0.000 0.000 0.000 0.000 1.167 1.347 0.033 0.029 0.000 0.000 0.000 0.000 1.250 1.447 0.036 0.030 0.000 0.000 0.000 0.000 1.333 1.547 0.039 0.031 0.000 0.000 0.000 0.000 1.417 1.647 0.042 0.032 0.000 0.000 0.000 0.000 1.500 1.747 0.044 0.033 0.000 0.000 0.000 0.000 1.583 1.847 0.047 0.034 0.000 0.000 0.000 0.000 Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 1.667 1.947 0.050 0.035 0.000 0.000 0.000 0.000 1.750 2.047 0.053 0.036 0.000 0.000 0.000 0.000 1.833 2.147 0.055 0.037 0.000 0.000 0.000 0.000 1.917 2.247 0.058 0.038 0.000 0.000 0.000 0.000 2.000 2.347 0.061 0.038 0.000 0.000 0.000 0.000 2.083 2.447 0.063 0.039 0.000 0.000 0.000 0.000 2.167 2.547 0.066 0.040 0.000 0.000 0.000 0.000 2.250 2.647 0.068 0.070 0.000 0.000 0.000 0.000 2.333 2.747 0.070 0.089 0.000 0.000 0.000 0.000 2.417 2.847 0.073 0.103 0.000 0.000 0.000 0.000 2.500 2.947 0.075 0.115 0.000 0.000 0.000 0.000 2.583 3.047 0.077 0.125 0.000 0.000 0.000 0.000 2.667 3.147 0.079 0.134 0.000 0.000 0.000 0.000 2.750 3.247 0.081 0.142 0.000 0.000 0.000 0.000 2.833 3.347 0.083 0.150 0.000 0.000 0.000 0.000 2.917 3.447 0.085 0.158 0.000 0.000 0.000 0.000 3.000 3.547 0.086 0.164 0.000 0.000 0.000 0.000 3.083 3.647 0.088 0.425 0.000 0.000 0.000 0.000 3.167 3.747 0.089 0.881 0.000 0.000 0.000 0.000 3.250 3.847 0.091 1.401 0.000 0.000 0.000 0.000 3.333 3.947 0.092 1.873 0.000 0.000 0.000 0.000 3.417 4.047 0.094 2.208 0.000 0.000 0.000 0.000 3.500 4.147 0.095 2.404 0.000 0.000 0.000 0.000 ___________________________________________________________________ ___________________________________________________________________ ANALYSIS RESULTS Stream Protection Duration ___________________________________________________________________ Predeveloped Landuse Totals for POC #1 Total Pervious Area:3.337 Total Impervious Area:0.067 ___________________________________________________________________ Mitigated Landuse Totals for POC #1 Total Pervious Area:1.479 Total Impervious Area:1.925 ___________________________________________________________________ Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.276347 5 year 0.455256 10 year 0.594289 25 year 0.792973 50 year 0.957606 100 year 1.136486 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0.11154 5 year 0.175194 10 year 0.229642 Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 25 year 0.31494 50 year 0.392195 100 year 0.482782 ___________________________________________________________________ Stream Protection Duration Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1949 0.486 0.087 1950 0.510 0.101 1951 0.323 0.245 1952 0.148 0.075 1953 0.106 0.083 1954 0.222 0.095 1955 0.236 0.104 1956 0.259 0.136 1957 0.340 0.094 1958 0.169 0.098 1959 0.148 0.087 1960 0.347 0.229 1961 0.258 0.094 1962 0.093 0.070 1963 0.267 0.093 1964 0.240 0.089 1965 0.326 0.117 1966 0.170 0.085 1967 0.519 0.101 1968 0.279 0.086 1969 0.311 0.087 1970 0.252 0.088 1971 0.330 0.100 1972 0.485 0.162 1973 0.130 0.096 1974 0.296 0.094 1975 0.361 0.101 1976 0.239 0.097 1977 0.222 0.076 1978 0.219 0.093 1979 0.130 0.073 1980 0.608 0.177 1981 0.247 0.083 1982 0.579 0.251 1983 0.248 0.101 1984 0.179 0.077 1985 0.215 0.086 1986 0.314 0.180 1987 0.303 0.210 1988 0.111 0.082 1989 0.093 0.079 1990 1.113 0.276 1991 0.710 0.234 1992 0.205 0.091 1993 0.134 0.085 1994 0.084 0.067 1995 0.203 0.104 1996 0.529 0.249 1997 0.348 0.235 Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 1998 0.239 0.086 1999 0.783 0.174 2000 0.272 0.104 2001 0.131 0.071 2002 0.455 0.180 2003 0.414 0.084 2004 0.568 0.314 2005 0.294 0.100 2006 0.289 0.097 2007 0.973 0.795 2008 0.697 0.372 2009 0.418 0.159 ___________________________________________________________________ Stream Protection Duration Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 1.1126 0.7951 2 0.9728 0.3719 3 0.7827 0.3141 4 0.7097 0.2763 5 0.6970 0.2510 6 0.6080 0.2485 7 0.5788 0.2450 8 0.5679 0.2350 9 0.5290 0.2338 10 0.5190 0.2295 11 0.5100 0.2099 12 0.4861 0.1805 13 0.4852 0.1801 14 0.4546 0.1773 15 0.4181 0.1741 16 0.4138 0.1618 17 0.3609 0.1593 18 0.3483 0.1361 19 0.3468 0.1173 20 0.3397 0.1038 21 0.3303 0.1038 22 0.3259 0.1037 23 0.3229 0.1014 24 0.3136 0.1011 25 0.3114 0.1010 26 0.3031 0.1007 27 0.2961 0.0998 28 0.2938 0.0996 29 0.2885 0.0982 30 0.2793 0.0975 31 0.2717 0.0974 32 0.2667 0.0962 33 0.2592 0.0955 34 0.2580 0.0942 35 0.2517 0.0941 36 0.2482 0.0939 37 0.2469 0.0934 38 0.2398 0.0930 39 0.2394 0.0905 40 0.2386 0.0890 Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 41 0.2364 0.0876 42 0.2219 0.0874 43 0.2216 0.0873 44 0.2194 0.0868 45 0.2146 0.0864 46 0.2054 0.0857 47 0.2029 0.0856 48 0.1785 0.0851 49 0.1700 0.0851 50 0.1688 0.0840 51 0.1484 0.0830 52 0.1481 0.0825 53 0.1339 0.0815 54 0.1310 0.0791 55 0.1301 0.0774 56 0.1298 0.0762 57 0.1110 0.0748 58 0.1062 0.0727 59 0.0930 0.0715 60 0.0925 0.0700 61 0.0837 0.0672 ___________________________________________________________________ Stream Protection Duration POC #1 The Facility PASSED The Facility PASSED. Flow(cfs) Predev Mit Percentage Pass/Fail 0.1382 4051 3377 83 Pass 0.1465 3371 2939 87 Pass 0.1547 2849 2485 87 Pass 0.1630 2374 1991 83 Pass 0.1713 2046 1632 79 Pass 0.1796 1770 1260 71 Pass 0.1878 1498 935 62 Pass 0.1961 1269 675 53 Pass 0.2044 1118 528 47 Pass 0.2127 980 374 38 Pass 0.2209 826 245 29 Pass 0.2292 675 186 27 Pass 0.2375 561 145 25 Pass 0.2458 470 110 23 Pass 0.2541 375 94 25 Pass 0.2623 317 85 26 Pass 0.2706 282 78 27 Pass 0.2789 251 68 27 Pass 0.2872 216 62 28 Pass 0.2954 193 56 29 Pass 0.3037 168 44 26 Pass 0.3120 155 36 23 Pass 0.3203 141 27 19 Pass 0.3285 128 27 21 Pass 0.3368 123 24 19 Pass 0.3451 115 23 20 Pass 0.3534 101 19 18 Pass Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 0.3617 95 17 17 Pass 0.3699 89 15 16 Pass 0.3782 87 13 14 Pass 0.3865 81 12 14 Pass 0.3948 73 12 16 Pass 0.4030 72 12 16 Pass 0.4113 67 12 17 Pass 0.4196 64 12 18 Pass 0.4279 62 11 17 Pass 0.4361 58 11 18 Pass 0.4444 53 11 20 Pass 0.4527 51 11 21 Pass 0.4610 48 10 20 Pass 0.4693 42 10 23 Pass 0.4775 40 10 25 Pass 0.4858 38 10 26 Pass 0.4941 35 10 28 Pass 0.5024 33 9 27 Pass 0.5106 32 9 28 Pass 0.5189 29 9 31 Pass 0.5272 28 9 32 Pass 0.5355 27 9 33 Pass 0.5438 25 9 36 Pass 0.5520 23 8 34 Pass 0.5603 23 7 30 Pass 0.5686 18 7 38 Pass 0.5769 16 7 43 Pass 0.5851 14 7 50 Pass 0.5934 14 7 50 Pass 0.6017 14 7 50 Pass 0.6100 13 7 53 Pass 0.6182 12 7 58 Pass 0.6265 11 6 54 Pass 0.6348 11 6 54 Pass 0.6431 11 6 54 Pass 0.6514 10 6 60 Pass 0.6596 8 6 75 Pass 0.6679 8 5 62 Pass 0.6762 8 5 62 Pass 0.6845 8 5 62 Pass 0.6927 8 4 50 Pass 0.7010 7 4 57 Pass 0.7093 7 4 57 Pass 0.7176 5 3 60 Pass 0.7258 5 3 60 Pass 0.7341 4 3 75 Pass 0.7424 4 2 50 Pass 0.7507 4 2 50 Pass 0.7590 4 2 50 Pass 0.7672 4 2 50 Pass 0.7755 4 2 50 Pass 0.7838 3 2 66 Pass 0.7921 2 1 50 Pass 0.8003 2 0 0 Pass 0.8086 2 0 0 Pass 0.8169 2 0 0 Pass 0.8252 2 0 0 Pass Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 0.8334 2 0 0 Pass 0.8417 2 0 0 Pass 0.8500 2 0 0 Pass 0.8583 2 0 0 Pass 0.8666 2 0 0 Pass 0.8748 2 0 0 Pass 0.8831 2 0 0 Pass 0.8914 2 0 0 Pass 0.8997 2 0 0 Pass 0.9079 2 0 0 Pass 0.9162 2 0 0 Pass 0.9245 2 0 0 Pass 0.9328 2 0 0 Pass 0.9411 2 0 0 Pass 0.9493 2 0 0 Pass 0.9576 2 0 0 Pass _____________________________________________________ ___________________________________________________________________ Water Quality BMP Flow and Volume for POC #1 On-line facility volume: 0 acre-feet On-line facility target flow: 0 cfs. Adjusted for 15 min: 0 cfs. Off-line facility target flow: 0 cfs. Adjusted for 15 min: 0 cfs. ___________________________________________________________________ LID Report LID Technique Used for Total Volume Volume Infiltration Cumulative Percent Water Quality Percent Comment Treatment? Needs Through Volume Volume Volume Water Quality Treatment Facility (ac-ft.) Infiltration Infiltrated Treated (ac-ft) (ac-ft) Credit Vault 1 POC N 389.06 N 0.00 SSD Table 1 POC N 83.36 N 0.00 Total Volume Infiltrated 472.42 0.00 0.00 0.00 0.00 0% No Treat. Credit Compliance with LID Standard 8 Duration Analysis Result = Failed ___________________________________________________________________ Perlnd and Implnd Changes No changes have been made. ___________________________________________________________________ This program and accompanying documentation are provided 'as-is' without warranty of any kind. The entire risk regarding the performance and results of this program is assumed by End User. Clear Creek Solutions Inc. and the governmental licensee or sublicensees disclaim all warranties, either expressed or implied, including but not limited to implied warranties of program and accompanying documentation. In no event shall Clear Creek Solutions Inc. be liable for any damages whatsoever (including without limitation to damages for loss of business profits, loss of business information, business interruption, and the like) arising out of the use of, or inability to use this program even if Clear Creek Solutions Inc. or their authorized representatives have been advised of the possibility of such damages. Software Copyright © by : Clear Creek Solutions, Inc. 2005-2024; All Rights Reserved. Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 January 2024 GENERAL USE LEVEL DESIGNATION FOR BASIC (TSS) METALS AND PHOSPHORUS TREATMENT For Contech Engineered Solutions, LLC (Contech) Modular Wetlands Linear Ecology’s Decision Based on Modular Wetland Systems, Inc, application submissions, including the Technical Evaluation Report, dated April 1, 2014, Ecology hereby issues the following use level designation: 1. General Use Level Designation (GULD) for the Modular Wetlands Linear Stormwater Treatment System for Basic, Phosphorus, and Metals treatment • Sized at a hydraulic loading rate of: • 1 gallon per minute (gpm) per square foot (sq ft) of Wetland Cell Surface Area • Prefilter box (approved at either 22 inches or 33 inches tall) • 3.0 gpm/sq ft of prefilter box surface area for moderate pollutant loading rates (low to medium density residential basins). • 2.1 gpm/sq ft of prefilter box surface area for high pollutant loading rates (commercial and industrial basins). 2. Ecology approves the Modular Wetlands Linear Stormwater Treatment System units for Basic, Phosphorus, and Metals treatment at the hydraulic loading rate listed above. Designers shall calculate the water quality design flow rates using the following procedures: • Western Washington: For treatment installed upstream of detention or retention, the water quality design flow rate is the peak 15-minute water quality treatment design flow rate as calculated using the latest version of the Western Washington Hydrology Model or other Ecology- approved continuous runoff model. Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 • Eastern Washington: For treatment installed upstream of detention or retention, the water quality design flow rate is the peak 15-minute water quality treatment design flow rate as calculated using one of the three methods described in Chapter 2.7.6 of the Stormwater Management Manual for Eastern Washington (SWMMEW) or local manual. • Entire State: For treatment installed downstream of detention, the water quality treatment design flow rate is the full 2-year release rate of the detention facility. 3. These use level designations have no expiration date but may be amended or revoked by Ecology, and are subject to the conditions specified below. Ecology’s Conditions of Use Applicants shall comply with the following conditions: 1) Design, assemble, install, operate, and maintain the Modular Wetlands Linear Stormwater Treatment System units, in accordance with Contech’s. applicable manuals and documents and the Ecology Decision. 2) Each site plan must undergo Contech review and approval before site installation. This ensures that site grading and slope are appropriate for use of a Modular Wetlands Linear Stormwater Treatment System unit. 3) Modular Wetlands Linear Stormwater Treatment System media shall conform to the specifications submitted to and approved by Ecology. 4) The applicant tested the Modular Wetlands Linear Stormwater Treatment System with an external bypass weir. This weir limited the depth of water flowing through the media, and therefore the active treatment area, to below the root zone of the plants. This GULD applies to Modular Wetlands Linear Stormwater Treatment Systems whether plants are included in the final product or not. 5) Maintenance: The required maintenance interval for stormwater treatment devices is often dependent upon the degree of pollutant loading from a particular drainage basin. Therefore, Ecology does not endorse or recommend a “one size fits all” maintenance cycle for a particular model/size of stormwater treatment technology. • Typically, Contech designs Modular Wetland systems for a target prefilter media life of 6 to 12 months. • Indications of the need for maintenance include effluent flow decreasing to below the design flow rate or decrease in treatment below required levels. • Owners/operators must inspect Modular Wetland systems for a minimum of twelve months from the start of post-construction operation to determine site-specific maintenance schedules and requirements. You must conduct inspections monthly during the wet season, and every other month during the dry season (According to the SWMMWW, the wet season in western Washington is October 1 to April 30. According to the SWMMEW, the wet Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 season in eastern Washington is October 1 to June 30). After the first year of operation, owners/operators must conduct inspections based on the findings during the first year of inspections. • Conduct inspections by qualified personnel, follow manufacturer’s guidelines, and use methods capable of determining either a decrease in treated effluent flowrate and/or a decrease in pollutant removal ability. • When inspections are performed, the following findings typically serve as maintenance triggers: • Standing water remains in the vault between rain events, or • Bypass occurs during storms smaller than the design storm. • If excessive floatables (trash and debris) are present (but no standing water or excessive sedimentation), perform a minor maintenance consisting of gross solids removal, not prefilter media replacement. • Additional data collection will be used to create a correlation between pretreatment chamber sediment depth and pre-filter clogging (see Issues to be Addressed by the Company section below) 6) Discharges from the Modular Wetlands Linear Stormwater Treatment System units shall not cause or contribute to water quality standards violations in receiving waters. Applicant: Contech Engineered Solutions, LLC Applicant’s Address: 11815 NE Glenn Widing Dr. Portland, OR 97220 Application Documents: Original Application for Conditional Use Level Designation, Modular Wetland System, Linear Stormwater Filtration System Modular Wetland Systems, Inc., January 2011 Quality Assurance Project Plan: Modular Wetland System – Linear Treatment System Performance Monitoring Project, draft, January 2011 Revised Application for Conditional Use Level Designation, Modular Wetland System, Linear Stormwater Filtration System Modular Wetland Systems, Inc., May 2011 Memorandum: Modular Wetland System-Linear GULD Application Supplementary Data, April 2014 Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 Technical Evaluation Report: Modular Wetland System Stormwater Treatment System Performance Monitoring, April 2014 Applicant’s Use Level Request: • General Use Level Designation as a Basic, Metals, and Phosphorus treatment device in accordance with Ecology’s Guidance for Evaluating Emerging Stormwater Treatment Technologies Technology Assessment Protocol – Ecology (TAPE) January 2011 Revision. Applicant’s Performance Claims: • The Modular Wetlands Linear is capable of removing a minimum of 80-percent of TSS from stormwater with influent concentrations between 100 and 200 mg/L. • The Modular Wetlands Linear is capable of removing a minimum of 50-percent of total phosphorus from stormwater with influent concentrations between 0.1 and 0.5 mg/L. • The Modular Wetlands Linear is capable of removing a minimum 30-percent of dissolved copper from stormwater with influent concentrations between 0.005 and 0.020 mg/L. • The Modular Wetlands Linear is capable of removing a minimum 60-percent of dissolved zinc from stormwater with influent concentrations between 0.02 and 0.30 mg/L. Ecology’s Recommendations: • Contech has shown Ecology, through laboratory and field-testing, that the Modular Wetlands Linear Stormwater Treatment System filter system is capable of attaining Ecology’s Basic, Phosphorus, and Metals treatment goals. Findings of Fact: Laboratory Testing The Modular Wetlands Linear Stormwater Treatment System has the: • Capability to remove 99 percent of total suspended solids (using Sil-Co-Sil 106) in a quarter-scale model with influent concentrations of 270 mg/L. • Capability to remove 91 percent of total suspended solids (using Sil-Co-Sil 106) in laboratory conditions with influent concentrations of 84.6 mg/L at a flow rate of 3.0 gpm per square foot of media. • Capability to remove 93 percent of dissolved Copper in a quarter-scale model with influent concentrations of 0.757 mg/L. • Capability to remove 79 percent of dissolved Copper in laboratory conditions with influent concentrations of 0.567 mg/L at a flow rate of 3.0 gpm per square foot of media. Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 • Capability to remove 80.5-percent of dissolved Zinc in a quarter-scale model with influent concentrations of 0.95 mg/L at a flow rate of 3.0 gpm per square foot of media. • Capability to remove 78-percent of dissolved Zinc in laboratory conditions with influent concentrations of 0.75 mg/L at a flow rate of 3.0 gpm per square foot of media. Field Testing • Modular Wetland Systems, Inc. conducted monitoring of an MWS-Linear (Model # MWS-L-4-13) from April 2012 through May 2013, at a transportation maintenance facility in Portland, Oregon. The manufacturer collected flow-weighted composite samples of the system’s influent and effluent during 28 separate storm events. The system treated approximately 75 percent of the runoff from 53.5 inches of rainfall during the monitoring period. The applicant sized the system at 1 gpm/sq ft. (wetland media) and 3gpm/sq ft. (prefilter). • Influent TSS concentrations for qualifying sampled storm events ranged from 20 to 339 mg/L. Average TSS removal for influent concentrations greater than 100 mg/L (n=7) averaged 85 percent. For influent concentrations in the range of 20-100 mg/L (n=18), the upper 95 percent confidence interval about the mean effluent concentration was 12.8 mg/L. • Total phosphorus removal for 17 events with influent TP concentrations in the range of 0.1 to 0.5 mg/L averaged 65 percent. A bootstrap estimate of the lower 95 percent confidence limit (LCL95) of the mean total phosphorus reduction was 58 percent. • The lower 95 percent confidence limit of the mean percent removal was 60.5 percent for dissolved zinc for influent concentrations in the range of 0.02 to 0.3 mg/L (n=11). The lower 95 percent confidence limit of the mean percent removal was 32.5 percent for dissolved copper for influent concentrations in the range of 0.005 to 0.02 mg/L (n=14) at flow rates up to 28 gpm (design flow rate 41 gpm). Laboratory test data augmented the data set, showing dissolved copper removal at the design flow rate of 41 gpm (93 percent reduction in influent dissolved copper of 0.757 mg/L). Issues to be addressed by the Company: 1. Contech should collect maintenance and inspection data for the first year on all installations in the Northwest in order to assess standard maintenance requirements for various land uses in the region. Contech should use these data to establish required maintenance cycles. 2. Contech should collect pre-treatment chamber sediment depth data for the first year of operation for all installations in the Northwest. Contech will use these data to create a correlation between sediment depth and pre-filter clogging. Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 Technology Description: Download at https://www.conteches.com/modular-wetlands Contact Information: Applicant: Jeremiah Lehman Contech Engineered Solutions, LLC 11815 NE Glenn Widing Dr. Portland, OR 97220 Jeremiah.Lehman@ContechES.com Applicant website: http://www.conteches.com Ecology web link: http://www.ecy.wa.gov/programs/wg/stormwater/newtech/index.html Ecology: Douglas C. Howie, P.E. Department of Ecology Water Quality Program (360) 870-0983 douglas.howie@ecy.wa.gov Revision History Date Revision June 2011 Original use-level-designation document September 2012 Revised dates for TER and expiration January 2013 Modified Design Storm Description, added Revision Table, added maintenance discussion, modified format in accordance with Ecology standard December 2013 Updated name of Applicant April 2014 Approved GULD designation for Basic, Phosphorus, and Enhanced treatment December 2015 Updated GULD to document the acceptance of MWS – Linear Modular Wetland installations with or without the inclusion of plants July 2017 Revised Manufacturer Contact Information (name, address, and email) December 2019 Revised Manufacturer Contact Address July 2021 Added additional prefilter sized at 33 inches August 2021 Changed “Prefilter” to “Prefilter box” November 2022 Changed Contacts to Contech ES January 2024 Revised Dissolved Metals (Enhanced) to Metals Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 LPD Engineering, PLLC Page 17 Renton Fire Station #16 Technical Information Report, November 12, 2024 APPENDIX C Construction Stormwater Pollution Prevention Plan (SWPPP) Narrative Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 LPD Engineering, PLLC Page 18 Renton Fire Station #16 Technical Information Report, November 12, 2024 APPENDIX D Operations and Maintenance Manual Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 LPD Engineering, PLLC Page 19 Renton Fire Station #16 Technical Information Report, November 12, 2024 APPENDIX E Facility Summaries, and Declaration of Drainage Covenant Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 LPD Engineering, PLLC Page 20 Renton Fire Station #16 Technical Information Report, November 12, 2024 APPENDIX F Special Reports and Studies Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 Geotechnical Engineering Services Fire Station 16 Replacement 15815 SE 128th Street Renton, Washington for Renton Regional Fire Authority August 5, 2022 Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 Geotechnical Engineering Services Fire Station 16 Replacement 15815 SE 128th Street Renton, Washington for Renton Regional Fire Authority August 5, 2022 17425 NE Union Hill Road, Suite 250 Redmond, Washington 98052 425.861.6000 Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 August 5, 2022 | Page i File No. 26016-001-00 Table of Contents 1.0 INTRODUCTION ........................................................................................................................................... 1 2.0 SCOPE OF SERVICES .................................................................................................................................. 1 3.0 FIELD EXPLORATIONS AND LABORATORY TESTING ................................................................................ 1 3.1. Field Explorations .................................................................................................................................... 1 3.2. Laboratory Testing .................................................................................................................................. 1 4.0 SITE CONDITIONS ........................................................................................................................................ 2 4.1. Area Geology ........................................................................................................................................... 2 4.2. Surface Conditions.................................................................................................................................. 2 4.3. Subsurface Conditions ........................................................................................................................... 2 4.4. Groundwater ........................................................................................................................................... 3 4.5. Geologically Hazardous Areas ................................................................................................................ 3 5.0 CONCLUSIONS AND RECOMMENDATIONS ............................................................................................... 4 5.1. Earthquake Engineering ......................................................................................................................... 6 5.1.1. Seismicity ..................................................................................................................................... 6 5.1.2. 2018 IBC Seismic Design Information ....................................................................................... 6 5.1.3. Liquefaction Potential ................................................................................................................. 7 5.1.4. Other Seismic Hazards ................................................................................................................ 7 5.2. Shallow Foundations .............................................................................................................................. 7 5.2.1. Foundation Settlement ............................................................................................................... 8 5.2.2. Lateral Resistance ....................................................................................................................... 8 5.3. Slab-On-Grade Floors .............................................................................................................................. 8 5.4. Below-Grade Walls and Retaining Walls ................................................................................................ 9 5.4.1. Design Parameters ...................................................................................................................... 9 5.4.2. Wall Drainage ............................................................................................................................ 10 5.5. Earthwork .............................................................................................................................................. 10 5.5.1. Clearing and Site Preparation ................................................................................................... 11 5.5.2. Subgrade Preparation ............................................................................................................... 11 5.5.3. Temporary Slopes and Construction Dewatering .................................................................... 12 5.5.4. Permanent Slopes ..................................................................................................................... 12 5.6. Structural Fill ......................................................................................................................................... 13 5.6.1. Materials .................................................................................................................................... 13 5.6.2. Use of On-site Soils.................................................................................................................... 13 5.6.3. Fill Placement and Compaction Criteria ................................................................................... 13 5.6.4. Weather Considerations ........................................................................................................... 14 5.6.5. Utility Trenches .......................................................................................................................... 15 5.6.6. Sedimentation and Erosion Control ......................................................................................... 15 5.7. Drainage Considerations ...................................................................................................................... 16 5.8. Pavement Design .................................................................................................................................. 16 5.9. Stormwater Infiltration Considerations................................................................................................ 17 6.0 DESIGN REVIEW AND CONSTRUCTION SERVICES ................................................................................. 17 7.0 LIMITATIONS ............................................................................................................................................. 17 8.0 REFERENCES ............................................................................................................................................ 18 Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 August 5, 2022 | Page ii File No. 26016-001-00 LIST OF FIGURES Figure 1. Vicinity Map Figure 2. Site Plan APPENDICES Appendix A. Field Explorations Figure A-1 – Key to Exploration Logs Figures A-2 through A-11 – Log of Borings Appendix B. Laboratory Testing Figures B-1 and B-2 – Sieve Analysis Results Appendix C. Report Limitations and Guidelines for Use Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 August 5, 2022 | Page 1 File No. 26016-001-00 1.0 INTRODUCTION GeoEngineers, Inc. (GeoEngineers) is pleased to submit this geotechnical engineering report for the Renton Regional Fire Authority (RRFA) Station 16 replacement project to be located at 15815 SE 128th Street in Renton, Washington. The site consists of three King County parcels (366450-0007, 366450-0008 and 366450-0009) totaling approximately 3 acres located on the south side of SE 128th Street, just east of 158th Avenue SE. The property extends roughly 200 feet along SE 128th Street and just over 600 feet to the south. The location of the site is shown in the Vicinity Map, Figure 1. We understand that the project concept consists of a new fire station building located in the north area of the site, a detached maintenance garage with five bays in the southeast area and surrounding drive aisles and parking areas. We anticipate that the fire station will be a two-story building, and that the detached maintenance garage will be a one-story building. Site development may also include infiltration facilities depending on feasibility. A site plan showing the conceptual overlay on the existing site features is included as Figure 2. 2.0 SCOPE OF SERVICES The purpose of our services is to evaluate subsurface soil and groundwater conditions as a basis for providing geotechnical engineering design and construction recommendations for the proposed Fire Station 16 replacement project. Our scope of services was completed in general accordance with our proposal dated April 22, 2022, and authorized on May 5, 2022. 3.0 FIELD EXPLORATIONS AND LABORATORY TESTING 3.1. Field Explorations Subsurface conditions were evaluated by drilling and sampling ten hollow-stem auger borings (GEI-1 through GEI-10) to depths ranging from about 10½ to 50½ feet below the existing ground surface (bgs). Approximate locations of the explorations are shown in Figure 2. Descriptions of the field exploration program and the boring logs are presented in Appendix A. 3.2. Laboratory Testing Soil samples were obtained during drilling and were transported to GeoEngineers’ laboratory for further evaluation. Selected samples were tested for the determination of moisture content, percent fines (material passing the U.S. No. 200 sieve) and grain size distribution (sieve analysis). The tests were performed in general accordance with test methods of ASTM International (ASTM) or other applicable procedures. A description of the laboratory testing and the test results are presented in Appendix B. Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 August 5, 2022 | Page 2 File No. 26016-001-00 4.0 SITE CONDITIONS 4.1. Area Geology The Puget Sound basin is a region of Quaternary (last 3 million years) sediments that range in thickness between 800 and 2,400 feet. Bedrock exposures are present on the basin margins to the east and west in the Cascade and Olympic Mountains, respectively. The basin area has been repeatedly overridden by Pleistocene (between 11,000 and 3 million years ago) continental glacial ice depositing till, glacial sand and gravel and glacially formed lake clay and silt. The repeated glacial action has resulted in numerous north-south trending ridges, with intervening valleys filled with post-glacial alluvium and/or marine deposits (Galster 1989). The most recent glacial cycle of sediment deposits is referred to as the Vashon Drift, occurring between 13,500 and 15,000 years ago. Published geologic information for the project area includes a United States Geological Survey (USGS) Geologic Map of the Renton Quadrangle, King County, Washington (Mullineaux 1965) and a Geologic Map of King County (Booth, Troost & Wisher 2007). The mapped surface geologic unit in the project area includes glacial till (Qgt). Glacial till generally consists of a non-sorted, non-stratified mixture of clay, silt, sand and gravel with larger constituents up to the size of boulders. The glacial till is very dense and relatively impermeable but can contain localized zones of interbedded stratified sand and gravel. Subsurface soil conditions encountered in our explorations are generally consistent with the geologic mapping. The borings generally encountered very soft/loose fill overlying medium dense to dense weathered glacial till and dense to very dense glacial till soils. 4.2. Surface Conditions The site is currently bounded by SE 128th Street to the north, and by single-family residential to the east, south and west. The site slopes up gently from approximately Elevation 530 feet in the northeast corner to approximately Elevation 551 feet in the southwest corner. A one-story wood-framed residential structure and a detached garage are currently located in the north-central portion of the site, and another one-story wood-framed residential structure is located in the southwestern portion. Gravel surfacing covers the central and northern areas of the site, and grass lawn is present in the south. 4.3. Subsurface Conditions GeoEngineers’ understanding of subsurface soil and groundwater conditions at the site is based on review of existing data and drilling and sampling ten hollow-stem auger borings (GEI-1 through GEI-10) to depths ranging from about 10½ to 50½ feet bgs at the approximate locations shown in Figure 2. The subsurface conditions at the site generally consist of crushed gravel surfacing and fill overlying weathered glacial till and glacial till soils. Each of these deposits are discussed separately below. ■ Crushed Gravel Surfacing (Existing Gravel Driveway): Crushed gravel was encountered in all of the explorations with the exception of borings GEI-6 through GEI-9, which were completed in landscape areas. The existing gravel driveway generally consists of approximately 6 inches of crushed rock mixed with underlying soft/loose fill soils. ■ Fill: Fill was encountered in all of the explorations with the exception of boring GEI-7. The fill generally consists of soft/loose to medium dense sandy silt/silty sand with variable organic and gravel content. The fill, where encountered, was observed to be approximately 2 to 7½ feet thick. Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 August 5, 2022 | Page 3 File No. 26016-001-00 ■ Weathered Glacial Till: Weathered glacial till was encountered in all of the explorations below the fill, and below the surficial topsoil/silty sand in GEI-7. The weathered glacial till generally consists of medium dense to dense silty sand with variable content and extends to a depth of about 4 to 9 feet bgs. ■ Glacial Till: Very dense unweathered glacial till was encountered in all of the explorations below the weathered soils. The unweathered glacial till generally consists of very dense silty sand with variable gravel content, beginning at a depth ranging from about 5 to 10 feet bgs and extending to the depths explored (up to 50½ feet bgs). 4.4. Groundwater Groundwater was not observed in the borings at the time of drilling, with the exception of the deepest boring, GEI-9, which was open for a longer period. We observed groundwater at approximately 10 feet below the existing ground surface at the time of drilling boring GEI-9. Groundwater observations during drilling are often inaccurate due to the limited time the hole is left open and variable permeability of adjacent soils. We anticipate a seasonally perched groundwater present at the site above the relatively impermeable dense to very dense glacial soils. Perched groundwater is common as seepage from precipitation and surface water runoff infiltrates through the upper fill and/or weathered glacial till soils and moves laterally or perches on the underlying dense/very dense glacial till soils. Groundwater conditions at the site are anticipated to fluctuate and vary as a function of location, precipitation, season and other factors such as below-grade drainage features. 4.5. Geologically Hazardous Areas We reviewed the critical areas inventory mapping on City of Renton Map View (COR Maps). Based on our review and our observations at the site, it is our opinion that the site does not have sensitive or protected slopes, and has low landslide, erosion, seismic and coal mine hazards. In accordance with City of Renton Municipal Code, Title IV, Chapter 3, Section 4-3-050G number 5, geologically hazardous areas are defined as: 1. Steep Slope Types: Sensitive Slopes: A hillside, or portion thereof, characterized by: (a) an average slope of twenty five percent (25 percent) to less than forty percent (40 percent) as identified in the City of Renton Steep Slope Atlas or in a method approved by the City; or (b) an average slope of forty percent (40 percent) or greater with a vertical rise of less than fifteen feet (15 feet) as identified in the City of Renton Steep Slope Atlas or in a method approved by the City; (c) abutting an average slope of twenty five percent (25 percent) to forty percent (40 percent) as identified in the City of Renton Steep Slope Atlas or in a method approved by the City. This definition excludes engineered retaining walls. Protected Slopes: A hillside, or portion thereof, characterized by an average slope of forty percent (40 percent) or greater grade and having a minimum vertical rise of fifteen feet (15') as identified in the City of Renton Steep Slope Atlas or in a method approved by the City. Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 August 5, 2022 | Page 4 File No. 26016-001-00 2. Landslide Hazards: Low Landslide Hazard (LL): Areas with slopes less than fifteen percent (15 percent). Medium Landslide Hazard (LM): Areas with slopes between fifteen percent (15 percent) and forty percent (40 percent) and underlain by soils that consist largely of sand, gravel or glacial till. High Landslide Hazards (LH): Areas with slopes greater than forty percent (40 percent), and areas with slopes between fifteen percent (15 percent) and forty percent (40 percent) and underlain by soils consisting largely of silt and clay. Very High Landslide Hazards (LV): Areas of known mapped or identified landslide deposits. 3. Erosion Hazards: Low Erosion Hazard (EL): Areas with soils characterized by the Natural Resource Conservation Service (formerly U.S. Soil Conservation Service) as having slight or moderate erosion potential, and a slope less than fifteen percent (15 percent). High Erosion Hazard (EH): Areas with soils characterized by the Natural Resource Conservation Service (formerly U.S. Soil Conservation Service) as having severe or very severe erosion potential, and a slope more than fifteen percent (15 percent). 4. Seismic Hazards: Low Seismic Hazard (SL): Areas underlain by dense soils or bedrock. These soils generally have site classifications of A through D, as defined in the International Building Code, 2012. High Seismic Hazard (SH): Areas underlain by soft or loose, saturated soils. These soils generally have site classifications E or F, as defined in the International Building Code, 2012. 5. Coal Mine Hazards: Low Coal Mine Hazards (CL): Areas with no known mine workings and no predicted subsidence. While no mines are known in these areas, undocumented mining is known to have occurred. Medium Coal Mine Hazards (CM): Areas where mine workings are deeper than two hundred feet (200 feet) for steeply dipping seams, or deeper than fifteen (15) times the thickness of the seam or workings for gently dipping seams. These areas may be affected by subsidence. High Coal Mine Hazard (CH): Areas with abandoned and improperly sealed mine openings and areas underlain by mine workings shallower than two hundred feet (200 feet) in depth for steeply dipping seams, or shallower than fifteen (15) times the thickness of the seam or workings for gently dipping seams. These areas may be affected by collapse or other subsidence. No regulated (sensitive and/or protected) slopes are mapped by COR Maps or were observed at the site. Therefore, it is our opinion that these geologically hazards will not adversely impact and/or limit the proposed development. 5.0 CONCLUSIONS AND RECOMMENDATIONS Based on our explorations, testing, and analyses, it is our opinion that the site is generally suitable for the proposed project from a geotechnical engineering standpoint, provided the recommendations in this report are included in design and construction. The following summary is presented for introductory purposes only and should be used in conjunction with the complete recommendations presented in this report. Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 August 5, 2022 | Page 5 File No. 26016-001-00 ■ The site is designated as Site Class C per the 2018 International Building Code (IBC), based on the average blowcounts in borings completed at the site. ■ The on-site soils contain a sufficient percentage of fines (material passing the U.S. Standard No.200 sieve) and are highly moisture sensitive. These soils will become disturbed from earthwork occurring during periods of wet weather (October through May), or when the moisture content of the soil is more than a few percentage points above optimum. Wet weather construction practices will be required unless earthwork occurs during the dry summer months (typically mid-July to mid-September). ■ A majority of the site is mantled with fill with variable organic content. The upper portion of the fill encountered in the borings completed within the footprint of the proposed structures was soft/loose. These soils will need to be removed and replaced with structural fill for building and slab support. We recommend shallow foundations be supported on a minimum 2-foot thickness of structural fill, or on the recompacted medium dense glacial soils. The structural fill pad should extend a minimum distance outside the footing as described in Section 5.2. ■ We recommend an allowable soil bearing pressure of 3,000 pounds per square foot (psf) where footings are founded on compacted structural fill or the recompacted medium dense native glacial soils as described above. A higher bearing pressure of 6.000 psf is feasible at depth where very dense unweathered glacial till was encountered. Based on the conditions in the borings, the top of the very dense glacial till varies from 5 to 10 feet below the existing ground surface. ■ Fill material encountered at subgrade elevation should be evaluated by GeoEngineers during construction. Soft/loose fill or fill with significant debris or unsuitable material should be removed to firm material and replaced with compacted structural fill. The depth of overexcavation will be based on the soils encountered and the type of structural improvement (e.g. footings, pavement or other hardscape). ■ New slabs-on-grade should be supported on a minimum 18-inch thickness of structural fill. We recommend a minimum 6-inch-thick capillary break layer beneath all slabs to provide uniform support and drainage. A subgrade modulus of 125 pounds per cubic inch (pci) may be used for design. ■ We recommend temporary slopes be inclined at 1½H:1V (horizontal to vertical) or flatter. Steeper cut slopes are possible in the dense to very dense native glacial soils (up to 1H:1V) provided groundwater seepage is not encountered or is controlled during construction. Slope inclinations may have to be modified by the contractor if localized sloughing occurs (particularly if loose fill soils are encountered). We recommend the Geotechnical Engineer evaluate the stability of cut slopes to confirm subsurface soils are as anticipated. ■ Design of infiltration facilities will be constrained at the site because of the relatively high percentage of fines and low permeability of the native glacial soils. We anticipate the native glacial soils will have a very slow infiltration rate (permeability on the order of 10-5 to 10 6 centimeters per second or typical infiltration rates less than 0.1 inches per hour). Furthermore, we anticipate a seasonally perched groundwater will be present above the weathered glacial till and/or relatively unweathered glacial till soils. Depending on the design configuration, below-grade infiltration facilities are likely not feasible due to seasonally perched groundwater and the hydraulic restrictive layers encountered at the site. Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 August 5, 2022 | Page 6 File No. 26016-001-00 5.1. Earthquake Engineering 5.1.1. Seismicity The Puget Sound region is located at the convergent continental boundary known as the Cascadia Subduction Zone (CSZ), which extends from mid-Vancouver Island to Northern California. The CSZ is the zone where the westward advancing North American Plate is overriding the subducting Juan de Fuca Plate. The interaction of these two plates results in three potential seismic source zones: (1) a shallow crustal source zone; (2) the Benioff source zone; and (3) the CSZ interplate source zone. The shallow crustal source zone is used to characterize shallow crustal earthquake activity within the North American Plate at depths ranging from 3 to 19 miles bgs. The closest known fault is the Seattle Fault Zone, which is mapped roughly 1 mile northwest of the project. Washington Department of Resources Geological Survey and the USGS both recently (2021) updated their late Quarternary faults in western Washington and have the same traces. The Seattle fault zone is 4 to 6 km wide and extends approximately 70 kilometers (km) in the east-west direction across the Puget Lowland. It consists of south-dipping thrust faults and interpreted north-dipping back thrusts that partly underlie the Seattle metropolitan area. Evidence suggests the Seattle fault zone is kinematically linked to active faults that border the Olympic Massif including the Saddle Mountain deformation zone (Lamb et al. 2012). Paleoseismic evidence suggests a Mw 7 earthquake occurred on the Seattle Fault at 900-930 A.D. (Ten Brink et al. 2002). Per the 2014 United States National Seismic Hazard Map, the recurrence times for the events on the Seattle fault range from 1,000 to 5,000 years (Petersen et al. 2014). The Seattle Fault is capable of producing earthquakes up to about magnitude 7.2. The Yelm Canal Hydroelectric project is about 52 to 57 km south of the Seattle fault zone. The Benioff source zone is used to characterize intraplate, intraslab or deep subcrustal earthquakes. Benioff source zone earthquakes occur within the subducting Juan de Fuca Plate at depths between 20 and 40 miles. In recent years, three large Benioff source zone earthquakes occurred that resulted in some liquefaction in loose alluvial deposits and significant damage to some structures. The first earthquake, which was centered in the Olympia area, occurred in 1949 and had a Richter magnitude of 7.1. The second earthquake, which was centered between Seattle and Tacoma, occurred in 1965 and had a Richter magnitude of 6.5. The third earthquake, which was located in the Nisqually valley north of Olympia, occurred in 2001 and had a Richter magnitude of 6.8. The CSZ interplate source zone is used to characterize rupture of the convergent boundary between the subducting Juan de Fuca Plate and the overriding North American Plate. The depth of CSZ earthquakes is greater than 40 miles. No earthquakes on the CSZ have been instrumentally recorded; however, through the geologic record and historical records of tsunamis in Japan, it is believed that the most recent CSZ event occurred in 1700. 5.1.2. 2018 IBC Seismic Design Information For the site, we recommend the following 2018 IBC parameters for Site Class C, mapped risk-targeted maximum-considered earthquake (MCER) spectral response acceleration at short period (Ss), mapped MCER spectral response acceleration at 1-second period (S1), short period site coefficient (Fa), long period site coefficient (Fv), design spectral acceleration at 0.2-second period (SDS) and the design spectral acceleration at 1.0-second period (SD1). Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 August 5, 2022 | Page 7 File No. 26016-001-00 TABLE 1. 2018 IBC DESIGN PARAMETERS 2018 IBC Parameter1 Recommended Value Site Class C Short Period Spectral Response Acceleration, SS (percent g) 137.1 1-Second Period Spectral Response Acceleration, S1 (percent g) 46.9 Seismic Coefficient, Fa 1.2 Seismic Coefficient, FV 1.5 Short Period Design Spectral Response Acceleration, SDS (percent g) 109.7 1-Second Period Design Spectral Response Acceleration, SD1 (percent g) 46.9 Risk Category, Essential Facility IV Note: 1Parameters developed based on latitude 47.4872744 and longitude -122.1293471 using the Applied Technology Council (ATC) Hazards online tool (https://hazards.atcouncil.org/). 5.1.3. Liquefaction Potential Liquefaction is a phenomenon where soils experience a rapid loss of internal strength as pore water pressures increase in response to strong ground shaking. The increased pore water pressure may temporarily meet or exceed soil overburden pressures to produce conditions that allow soil and water to flow, deform, or erupt from the ground surface. Ground settlement, lateral spreading and/or sand boils may result from soil liquefaction. Structures, such as buildings and other site facilities, supported on or within liquefied soils may suffer foundation settlement or lateral movement that can be damaging. In general, soils that are susceptible to liquefaction include very loose to medium dense, clean to silty sands and some silt soils that are below the groundwater table. Based on the subsurface soil and groundwater conditions encountered in the explorations completed at the site, it is our opinion that the site has a low risk of liquefaction for a moderate to large design earthquake. 5.1.4. Other Seismic Hazards Due to the location of the site and the site’s topography, the risk of adverse impacts resulting from seismically induced slope instability, differential settlement, surface displacement due to faulting or lateral spreading is considered to be low. 5.2. Shallow Foundations We recommend that foundations for new structures be supported on recompacted medium dense to dense native glacial soils or on a minimum 2-foot thickness of structural fill. The zone of structural fill should extend beyond the faces of the footing a distance at least equal to the thickness of the structural fill and be compacted as recommended in the “Structural Fill” section of this report. The base of the excavation should be evaluated by a member of our firm prior to placing the structural fill zone. Any existing fill which contains significant organic material should be removed prior to placing structural fill. Where footings are founded on native medium dense to dense glacial soils, loose or disturbed soils should be removed and the subgrade should be compacted to a firm and unyielding condition following excavation. Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 August 5, 2022 | Page 8 File No. 26016-001-00 We recommend minimum widths of 16 and 24 inches for continuous and isolated spread footings, respectively. The exterior footings should be founded at least 18 inches below lowest adjacent finished grade. Interior footings should be founded at least 12 inches below bottom of slab or adjacent finished grade. For footings founded on structural fill or on the recompacted medium dense to dense native glacial soils, an allowable soil bearing pressure of 3,000 psf may be used for design. A higher bearing pressure of 6,000 psf can be utilized at depth where very dense glacial till is present. Based on our explorations, the depth to unweathered very dense glacial till varies from about 5 to 10 feet bgs. These values include a factor of safety of 3 and may be increased by one-third when considering transient loads, such as wind or seismic. The weight of the footing and any backfill over the footing may be neglected in determining the applied bearing pressure. The shallow foundation subgrade should be prepared as recommended in the “Subgrade Preparation” section below. 5.2.1. Foundation Settlement We estimate that the total static settlement of shallow foundations designed and constructed as recommended above will be less than 1 inch. We estimate that the differential settlement between comparably loaded isolated spread footings or along a 25-foot section of continuous footings will be less than ½-inch over a distance of 25 feet. The settlements will occur rapidly, essentially as loads are applied. Settlement could be greater than estimated if loose or disturbed soils are not removed prior to placing concrete. 5.2.2. Lateral Resistance The soil resistance available to resist lateral loads is a function of the frictional resistance which can develop on the base of footings and floor slab, and the passive resistance which can develop on the face of below-grade elements of the structure as these elements tend to move into the soil. For footings founded on structural fill placed and compacted in accordance with our recommendations in this report, the allowable frictional resistance may be computed using 0.35 applied to vertical dead-load forces. The allowable passive resistance on the face of footings may be computed using an equivalent fluid density of 300 pounds per cubic foot (pcf) (triangular distribution) where footings are poured neat against dense native soils or where surrounded by structural fill compacted to at least 95 percent of maximum dry density (MDD) (ASTM D 1557). The above coefficient of friction and passive equivalent fluid density values include a factor of safety of about 1.5. Resistance to passive pressure should be calculated from the bottom of adjacent floor slabs and paving, or below a depth of 1 foot where the adjacent area is unpaved. If soils adjacent to footings are disturbed during construction, the disturbed soils must be recompacted, otherwise the lateral passive resistance value must be reduced. 5.3. Slab-On-Grade Floors We recommend that conventional slabs be supported on a minimum 18-inch thickness of structural fill or on recompacted medium dense to dense native glacial soils. Where existing fill is present the subgrade should be over-excavated a minimum of 18 inches and the exposed fill should be re-compacted to a firm and unyielding condition, followed by placement of the minimum 18 inches of structural fill in two lifts. Additional over-excavation will be required if the existing fill cannot be compacted to a firm and unyielding condition. For slabs designed as a beam on an elastic foundation, a modulus of subgrade reaction of 125 pci may be used for subgrade soils prepared as recommended in the “Subgrade Preparation” section below. Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 August 5, 2022 | Page 9 File No. 26016-001-00 We recommend that slab-on-grade floors be underlain by a minimum 6-inch-thick capillary break to provide uniform support and drainage. The capillary break should consist of clean crushed gravel, with a maximum particle size of 1½ inches and negligible sand or silt such as the AASHTO Grading No. 67 in Section 9-03.1(4)C of the 2022 Washington State Department of Transportation (WSDOT) Standard Specifications. Because of the presence of fine-grained on-site soils, moisture should be expected at the subgrade surface. Where moisture vapor emission through the slab must be minimized (e.g., where tiled or carpeted floors will be utilized), a vapor retarding membrane or vapor barrier below the slab should be utilized. The contractor should be made responsible for maintaining the integrity of the vapor retarder during construction. It may also be prudent to apply a sealer to the slab to further retard the migration of moisture through the floor. We estimate that the total static settlement of slab-on-grade floors constructed as recommended above will be less than 1 inch. Settlement could be greater than estimated if loose or disturbed soils are not removed prior to placing concrete. We recommend that concrete slabs be jointed around columns to allow the individual structural elements to settle differentially. 5.4. Below-Grade Walls and Retaining Walls The following recommendations should be used for the design of below-grade walls that are intended to act as retaining walls and for other retaining structures that are used to achieve grade changes. 5.4.1. Design Parameters Lateral earth pressures for design of below-grade walls and retaining structures should be evaluated using an equivalent fluid density of 35 pcf provided that the walls will not be restrained against rotation when backfill is placed. If the walls will be restrained from rotation, we recommend using an equivalent fluid density of 55 pcf. Walls are assumed to be restrained if top movement during backfilling is less than H/1000, where H is the wall height. These lateral soil pressures assume that the ground surface behind the wall is horizontal. For unrestrained walls with backfill sloping up at 2H:1V, the design lateral earth pressure should be increased to 55 pcf, while restrained walls with a 2H:1V sloping backfill should be designed using an equivalent fluid density of 75 pcf. These lateral soil pressures do not include the effects of surcharges such as floor loads, traffic loads or other surface loading. Surcharge effects should be included as appropriate. Seismic earth pressures should also be considered in design using a rectangular distribution of 8H in psf, where H is the wall height. If vehicles can approach the top of the wall to within half of the height of the wall, a traffic surcharge should be added to the wall pressure. For car parking areas, the traffic surcharge can be approximated by the equivalent weight of an additional 1 foot of soil backfill (about 125 psf) behind the wall. For fire truck, delivery truck parking areas and access driveway areas, the traffic surcharge can be approximated by the equivalent weight of an additional 2 feet (250 psf) of soil backfill behind the wall. Positive drainage should be provided behind below-grade walls and retaining structures as discussed below. These recommendations assume that all retaining walls will be provided with adequate drainage. The values for soil bearing, frictional resistance and passive resistance presented for shallow foundation design are applicable to retaining wall design. Walls located in level ground areas should be founded at a depth of 18 inches below the adjacent grade. Deeper embedment will be required where walls are founded on sloping ground and should be evaluated when the wall location and site grades are determined. Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 August 5, 2022 | Page 10 File No. 26016-001-00 5.4.2. Wall Drainage To reduce the potential for hydrostatic water pressure buildup behind retaining walls, we recommend that the walls be provided with adequate drainage. Wall drainage can be achieved by using free draining wall drainage material with perforated pipes to discharge the collected water. Wall drainage material may consist of Gravel Backfill for Drains per the WSDOT Standard Specifications Section 9-03.12(4) surrounded with a nonwoven geotextile filter fabric such as Mirafi 140N (or approved equivalent), or imported Gravel Borrow with less than 5 percent fines may be used in conjunction with a geocomposite wall drainage layer. The zone of wall drainage material should be 2 feet wide and should extend from the base of the wall to within 2 feet of the ground surface. The wall drainage material should be covered with a geotextile separator (such as Mirafi 140N) within about 2 feet of the ground surface and overlain by less permeable material such as the on-site silty sand that is properly moisture conditioned and compacted. A 4-inch-diameter perforated drainpipe should be installed within the free-draining material at the base of each wall. We recommend using either heavy-wall solid pipe (SDR-35 PVC) or rigid corrugated polyethylene pipe (ADS N-12, or equal). We recommend against using flexible tubing for the wall drainpipe. If gravel borrow is used against the wall in conjunction with a geocomposite wall drainage layer, then the drainage pipe at the base of the wall should be surrounded with at least 12 inches of Gravel Backfill for Drains per the WSDOT Standard Specifications Section 9-03.12(4) that is wrapped with a nonwoven geotextile filter fabric such as Mirafi 140N (or approved equivalent). The pipes should be laid with minimum slopes of one-quarter percent and discharge into the storm water collection system to convey the water off site. The pipe installations should include a cleanout riser with cover located at the upper end of each pipe run. The cleanouts could be placed in flush mounted access boxes. Collected downspout water should be routed to appropriate discharge points in separate pipe systems. 5.5. Earthwork Based on the subsurface soil and groundwater conditions encountered in the explorations completed at the site, we anticipate the fill and native glacial soils at the site may be excavated with conventional heavy-duty construction equipment, such as trackhoes or dozers. It may be necessary to rip the glacial soils in localized areas to facilitate excavation. Glacial deposits in the area commonly contain cobbles and boulders that may be encountered during excavation, and the contractor should be prepared to deal with these conditions during construction. Likewise, the surficial fill may contain foundations and/or utilities from previous site development, as well as debris, rubble, and/or cobbles and boulders. We recommend that procedures be identified in the project specifications for measurements and payment of work associated with obstructions. The fill and native glacial soils contain a high percent of fines (material passing the U.S. Standard No.200 sieve) and are highly moisture-sensitive and susceptible to disturbance, especially during wet weather construction (October through May). Repeated construction traffic will result in considerable disturbance during wet weather. Ideally, earthwork should be undertaken during extended periods of dry weather (June through September) when the surficial soils will be less susceptible to disturbance and provide better Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 August 5, 2022 | Page 11 File No. 26016-001-00 support for construction equipment. Dry weather construction will help reduce earthwork costs. We suggest that a contingency be included in the project schedule and budget to account for increased subgrade preparation and import costs, and placement of an all-weather access pad if construction occurs during the wet season. 5.5.1. Clearing and Site Preparation All areas to receive fill, structures or pavements should be cleared of vegetation, topsoil, existing asphalt and concrete. Clearing should consist of removal of all shrubs, sod, and other vegetation within the designated clearing limits. All existing foundations and subsurface structures should be removed. Debris associated with building and site work demolition should be removed from the site. Organic materials could be chipped/composted and reused in landscape areas, if desired. We anticipate that the depth of stripping to remove topsoil will be up to 2 feet, where present. Actual stripping depths should be determined based on field observations at the time of construction. We recommend materials that cannot be used for landscaping or protection of disturbed areas be removed from the project site. 5.5.2. Subgrade Preparation We recommend that prepared subgrades for slab-on-grade floors, foundations or pavement be observed by a representative of GeoEngineers to evaluate the suitability of the subgrade and identify any area of soft, yielding, pumping or otherwise unsuitable soils. The exposed foundation subgrade areas should be probed with a ½-inch-diameter steel probe rod, while new slab-on-grade and pavement subgrade areas should be proof-rolled with a loaded dump truck or equivalent. If unsuitable soils are revealed during probing and/or proof-roll, the unsuitable soils should be removed and replaced with structural fill, as needed. Fill material at subgrade elevation should be evaluated by GeoEngineers during construction. Soft/loose fill or fill with significant debris or unsuitable material should be removed as recommended and replaced with compacted structural fill. The width of the overexcavation should extend beyond the edge of the footing a distance equal to the depth of the overexcavation below the base of the footing. We recommend loose or disturbed soils be removed before placing concrete and reinforcing steel. Foundation bearing surfaces should not be exposed to standing water. If water infiltrates and pools in the excavation, the water, along with any disturbed soil, should be removed before placing reinforcing steel. A thin layer (2 to 3 inches) of crushed rock can be used to provide protection to the subgrade from light foot traffic. Compaction should be performed as described in the “Fill Placement and Compaction Criteria” section. We recommend GeoEngineers observe all foundation excavations before placing concrete forms and reinforcing steel to determine that bearing surfaces have been adequately prepared in accordance with our recommendations and the project plans and specifications and the soil conditions are consistent with those observed during our explorations. Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 August 5, 2022 | Page 12 File No. 26016-001-00 5.5.3. Temporary Slopes and Construction Dewatering We recommend temporary cut slopes in the existing fill and medium dense to dense weathered glacial till deposits be inclined at 1½H:1V or flatter, and dense to very dense glacial till deposits be inclined at 1H:1V or flatter. Flatter slopes may be necessary if seepage is present on the face of the cut slopes or if localized sloughing occurs. However, temporary cuts should be discussed with the geotechnical engineer during final design development to evaluate suitable cut slope inclinations for the various portions of the excavation. Temporary cut slopes should be planned such that they do not encroach on a 1H:1V influence line projected down from the edges of nearby or planned foundation elements. The above guidelines assume that surface loads such as traffic, construction equipment, stockpiles or building supplies will be kept away from the top of the cut slopes a sufficient distance so that the stability of the excavation is not affected. We recommend that this distance be at least 5 feet from the top of the cut for temporary cuts made at 1H:1V or flatter and less than 10 feet high, and no closer than a distance equal to one-half the height of the slope for cuts more than 10 feet high. Water that enters the excavations must be collected and routed away from prepared subgrade areas. We expect that this may be accomplished by installing a system of drainage ditches and sumps along the toe of the cut slopes. Some sloughing and raveling of the cut slopes should be expected. Temporary covering, such as heavy plastic sheeting with appropriate ballast, should be used to protect these slopes during periods of wet weather. Surface water runoff from above cut slopes should be prevented from flowing over the slope face by using berms, drainage ditches, swales or other appropriate methods. If temporary cut slopes experience excessive sloughing or raveling during construction, it may become necessary to modify the cut slopes to maintain safe working conditions. Slopes experiencing problems can be flattened, regraded to add intermediate slope benches, or additional dewatering can be provided if the poor slope performance is related to groundwater seepage. Because the contractor has control of the construction operations, the contractor should be made responsible for the dewatering of the site, shoring, stability of cut slopes, as well as the safety of the excavations. The contractor is present at the site continuously and is best able to observe changes in site and soil conditions and monitor the performance of excavations. Slope inclinations may have to be modified by the contractor if localized sloughing occurs or if seepage occurs. All dewatering, shoring and temporary slopes should conform to applicable local, state, and federal safety regulations. 5.5.4. Permanent Slopes We recommend that permanent cut and fill slopes be constructed no steeper than 2H:1V. To achieve uniform compaction, we recommend that fill slopes be overbuilt slightly and subsequently cut back to expose properly compacted fill. To reduce erosion, newly constructed slopes should be planted or hydroseeded shortly after completion of grading. Until the vegetation is established, some sloughing and raveling of the slopes should be expected. This may require localized repairs and reseeding. Temporary covering, such as jute fabric, loose straw or excelsior matting should be used to protect the slopes during periods of rainfall and aid in effective revegetation. Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 August 5, 2022 | Page 13 File No. 26016-001-00 5.6. Structural Fill 5.6.1. Materials We recommend that the 2022 WSDOT Standard Specifications be used to specify structural fill materials. Materials used to raise site grades, support structures, placed behind retaining structures, placed below pavements and sidewalks, and for utility trench backfill is classified as structural fill for the purpose of this report. Structural fill material requirements vary depending upon their use as described below: 1. As a minimum, structural fill placed in pavement areas, sloped fill embankments, hardscape features such as sidewalks, utility trench backfill and beneath new foundations and floor slabs should meet the criteria for Common Borrow, Section 9-03.14(3) of the WSDOT Standard Specifications. Common Borrow will be suitable for use as structural fill during prolonged dry weather conditions only and must be moisture conditioned to within 2 percent of the optimum moisture content. 2. During wet weather, structural fill should consist of imported material meeting the requirements of Gravel Borrow, Section 9-03.14(1) of the WSDOT Standard Specifications, with the restriction that the fines content (material passing the U.S. No. 200 sieve) be limited to no more than 5 percent. 3. Structural fill placed as capillary material should consist of a 6-inch-thick layer of clean crushed gravel with a maximum particle size of 1½ inches and negligible sand or silt and meet the requirements of AASHTO Grading No. 67 in Section 9-03.1(4)C of the WSDOT Standard Specifications. 4. Structural fill placed behind retaining walls should meet the requirements of Gravel Backfill for Walls, Section 9-03.12(2) of the WSDOT Standard Specifications. 5. Structural fill placed around perimeter footing drains and cast-in-place wall drains should meet the requirements of Gravel Backfill for Drains, Section 9-03.12(4) of the WSDOT Standard Specifications. 6. Structural fill placed as crushed surfacing base course (CSBC) below pavements and sidewalks should meet the requirements of Crushed Surfacing, Section 9-03.9(3) of the WSDOT Standard Specifications. 5.6.2. Use of On-site Soils The on-site soils contain a high percentage of fines (silt and clay) and are therefore moisture sensitive. These soils will be difficult to handle and compact during wet weather conditions (typically October through May). Additionally, the results of our laboratory analyses indicate the moisture content of the surficial soils are more than double the optimum content required for adequate compaction. These soils will only be suitable if prolonged aeration/disking can be provided on site. Soils excavated below a depth of about 5 feet have lower moisture contents, and are likely suitable for reuse as common borrow during the dry season. Based on these conditions, we recommend the contract documents provide provisions for import structural fill. 5.6.3. Fill Placement and Compaction Criteria Structural fill should be mechanically compacted to a firm, non-yielding condition. In general, structural fill should be placed in loose lifts not exceeding 12 inches in thickness when using heavy compaction equipment and 6 inches when using hand operated compaction equipment. Each lift should be conditioned to the proper moisture content and compacted to the specified density before placing subsequent lifts. Structural fill should be compacted to the following criteria: Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 August 5, 2022 | Page 14 File No. 26016-001-00 ■ Structural fill placed below foundations, on-grade slabs, and within the top 2 feet of pavement subgrade should be compacted to at least 95 percent of the MDD estimated in accordance with ASTM D 1557. Structural fill placed below the top 2 feet of pavement subgrade should be compacted to at least 90 percent of the MDD. ■ Structural fill placed in new pavement or hardscape areas, including utility trench backfill, should be compacted to 90 percent of the MDD estimated in general accordance with ASTM D 1557, except that the upper 2 feet of fill below final subgrade should be compacted to at least 95 percent of the MDD. ■ Structural fill placed behind below-grade or retaining walls, within a distance equal to the height of the wall, should be compacted to between 90 and 92 percent of the MDD estimated in general accordance with ASTM D 1557. Care should be taken when placing fill near the face of walls to avoid over-compaction and, hence overstressing the walls. ■ Structural fill placed as crushed rock base course below pavements should be compacted to at least 95 percent of the MDD estimated in accordance with ASTM D 1557. We recommend that a representative from our firm observe and evaluate (proof-rolling and/or probing) the exposed subgrade soils in structure and pavement areas prior to placement of structural fill and during the placement and compaction of structural fill. Our representative would evaluate the adequacy of the subgrade soils and identify areas needing further work, perform in-place moisture-density tests in the fill to evaluate if the work is being done in accordance with the compaction specifications, and advise on any modifications to procedures that may be appropriate for the prevailing conditions. 5.6.4. Weather Considerations As discussed previously, the native soils contain a sufficient percentage of fines (silt and clay) to be moisture sensitive. When the moisture content of these soils is appreciably above the optimum moisture content, these soils become muddy and unstable, operation of equipment on these soils will be difficult, and it will be difficult to meet the required compaction criteria. These soils should be protected from moisture and precipitation in order to be re-used as structural fill. Additionally, disturbance of these near surface soils should be expected if earthwork is completed during periods of wet weather. During wet weather conditions we recommend that: ■ The ground surface in and around the work area should be sloped so that surface water is directed away from work area to a sump or discharge location. ■ The ground surface should be graded such that areas of ponded water do not develop. ■ The contractor should take measures to prevent surface water from collecting in excavations and trenches. ■ Measures should be implemented to remove surface water from the work area. ■ Earthwork activities should not take place during periods of heavy precipitation. ■ Slopes with exposed soils should be covered with plastic sheeting or similar means, as practical. Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 August 5, 2022 | Page 15 File No. 26016-001-00 ■ The contractor should take necessary measures to prevent soils to be used as fill from becoming wet or unstable. These measures may include covering stockpiles with plastic sheeting, sumps with pumps and grading. The site soils should not be left uncompacted and exposed to moisture. Sealing the surficial soils by rolling with a smooth-drum roller prior to periods of precipitation will reduce the extent to which these soils become wet or unstable. ■ Construction activities should be scheduled so that the length of time that soils are left exposed to moisture is reduced to the extent practicable. ■ Structural fill placed during the wet season should meet the requirements previously recommended in the “Materials” section of this report. 5.6.5. Utility Trenches Trench excavation, pipe bedding, and trench backfilling should be completed using the general procedures described in the 2022 WSDOT Standard Specifications or other suitable procedures required by the City of Renton or specified by the project civil engineer. The soils encountered at the site are generally of low corrosivity based on our experience in the Puget Sound area. Utility trench backfill should consist of structural fill and should be placed in loose lifts not exceeding 12 inches in thickness when using heavy compaction equipment and not more than 6 inches when using hand operated compaction equipment such that adequate compaction can be achieved throughout the lift. Each lift must be compacted prior to placing the subsequent lift. Prior to compaction, the backfill should be moisture conditioned to within 2 percent of the optimum moisture content, if necessary. The backfill should be compacted in accordance with the criteria discussed above. 5.6.6. Sedimentation and Erosion Control Potential sources or causes of erosion and sedimentation depend upon construction methods, slope length and gradient, amount of soil exposure or disturbance, soil type, construction sequencing and weather. The project impact on erosion-prone areas and adjacent areas can be reduced by implementing an erosion and sedimentation control plan. The plan should be designed in accordance with applicable City standards. The plan should incorporate basic planning principles that include: ■ Scheduling grading and construction to reduce soil exposure, ■ Retaining existing vegetation whenever feasible, ■ Prevent erosion from occurring by minimizing the area of disturbance; providing blanket protection of disturbed areas and grading to avoid concentration of surface runoff onto or off of cut or fill slopes, access roadways or natural slopes, ■ Intercept surface runoff onto or off of disturbed areas to minimize sediment transport by use of brush barriers, straw wattles, swales, etc., ■ Provide erosion control system redundancies. For example, combine the above preventive measures with installation of silt fences, straw bales, and rock check dams where appropriate to provide the desired redundancy, ■ Inspect and maintain erosion control measures frequently; and ■ Hydroseed or place crushed rock surfacing on disturbed areas as soon as possible after completion. Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 August 5, 2022 | Page 16 File No. 26016-001-00 Erosion protection of finished surfaces may be obtained by planting vegetation and covering the area with mulch or matting. Numerous products are available to cover the exposed area including jute matting, excelsior matting, woven straw matting, synthetic fiber matting, seed impregnated sheeting and sprayed fibers. Until the permanent erosion protection is established, and the site is stabilized, site monitoring should be performed by qualified personnel to evaluate the effectiveness of the erosion control measures and repair and/or modify them as appropriate. Provisions for modifications to the erosion control system based on monitoring observations should be included in the erosion and sedimentation control plan. 5.7. Drainage Considerations The finished ground surface adjacent to the new structures should be sloped so that surface runoff flows away from the structure. Roof drains should be tightlined to an appropriate discharge point and should not be connected to footing or wall drains. All drains should be tightlined to the existing or new drainage system. A perimeter footing drain should be constructed around the perimeter of buildings and discharge into the stormwater collection system. 5.8. Pavement Design New pavement subgrade areas should be proofrolled and evaluated by the geotechnical engineer prior to placing base course. It is critical that all construction traffic be kept off the silty subgrade soils during wet weather to prevent disturbance (rutting and weaving) from occurring. We recommend the minimum 6-inch-thick crushed surfacing base course contain less than 5 percent passing the U.S. No. 200 sieve to perform as a drainage layer between the silty soils and the pavement section. The minimum thickness is not intended to serve as a working surface for construction traffic during wet weather. Additional subbase will likely be required if earthwork and site grading is not completed during the dry season. Based on our previous experience with similar projects, we recommend the minimum pavement sections outlined in Table 2. Portland cement concrete (PCC) sections may be considered for areas where concentrated heavy loads may occur. If site specific traffic data and load information is available, we can refine our recommendations for the conditions at Station 16. TABLE 2. RECOMMENDED PAVEMENT SECTIONS Section PCC Thickness (inches) HMA Thickness (inches) CSBC Thickness (inches) Heavy-Duty (fire truck access) 10 - 6 Heavy-Duty (drive aisles and access road) - 4 8 Light-Duty (automobile parking) 2½ 6 Notes: HMA – hot-mix asphalt If the City has a thicker standard thickness of concrete for the fire truck aprons, the City standard should be used. We recommend the CSBC conform to WSDOT Standard Specifications Section 9-03.9(3), “Crushed Surfacing.” The top 2 inches may conform to the gradation for “Top Course and Keystone,” the underlying base course should conform to the gradation for “Base Course.” We recommend the CSBC be placed as Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 August 5, 2022 | Page 17 File No. 26016-001-00 previously recommended and compacted to at least 95 percent of the MDD based on ASTM D 1557. Hot-mix asphalt (HMA) pavement should be compacted to at least 92 percent of the theoretical Rice Density. Our recommended PCC thickness is based on the assumption that the PCC slab will consist of plain-jointed (non-doweled) concrete. 5.9. Stormwater Infiltration Considerations We understand that shallow infiltration may be considered at the site within the northeast area (topographic low). The opportunity for shallow infiltration will be limited and constrained because of the relatively high percentage of fines and low permeability of the underlying native glacial soils. Very dense glacial till was encountered at a depth of 7 feet in our exploration (GEI-1). This layer is considered a hydraulic restrictive layer per the 2017 City of Renton Surface Water Design Manual (CORSWDM). A seasonally perched groundwater condition is also likely, further restricting infiltration at the site. If limited infiltration is being considered in the upper weathered zones, these facilities will require underdrain pipes decanting excess flows from a storage layer to both provide treatment of stormwater and take advantage of limited infiltration through the glacial deposits. Additional evaluation is required to determine feasibility of limited infiltration, such as evaluation of seasonal changes in groundwater and on- site small scale pilot infiltration tests. 6.0 DESIGN REVIEW AND CONSTRUCTION SERVICES Recommendations provided in this report are based on the assumptions and preliminary design information stated herein. We welcome the opportunity to review and discuss construction plans and specifications for this project as they are being developed. In addition, GeoEngineers should be retained to review the geotechnical-related portions of the plans and specifications to evaluate whether they are in conformance with the recommendations provided in this report. Satisfactory foundation and earthwork performance depend to a large degree on quality of construction. Sufficient monitoring of the contractor’s activities is a key part of determining that the work is completed in accordance with the construction drawings and specifications. Subsurface conditions observed during construction should be compared with those encountered during the subsurface explorations. Recognition of changed conditions often requires experience; therefore, qualified personnel should visit the site with sufficient frequency to detect whether subsurface conditions change significantly from those anticipated. We recommend that GeoEngineers be retained to observe construction at the site to confirm that subsurface conditions are consistent with the site explorations and to confirm that the intent of project plans and specifications relating to earthwork and foundation construction are being met. 7.0 LIMITATIONS We have prepared this report for the exclusive use of Renton Regional Fire Authority (RRFA) and their authorized agents and/or regulatory agencies for the proposed Station 16 replacement project at 15815 SE 128th Street in Renton, Washington. Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 August 5, 2022 | Page 18 File No. 26016-001-00 This report is not intended for use by others and the information contained herein is not applicable to other sites. No other party may rely on the product of our services unless we agree in advance and in writing to such reliance. Within the limitations of scope, schedule and budget, our services have been executed in accordance with generally accepted practices in the area at the time this report was prepared. No warranty or other conditions, express or implied, should be understood. Please refer to Appendix C, Report Limitations and Guidelines for Use, for additional information pertaining to use of this report. 8.0 REFERENCES ASCE 7-16, 2016, “Minimum design loads for buildings and other structures.” Applied Technology Council, “Hazards by Location, Seismic” accessed via: https://hazards.atcouncil.org/#/ on July 7, 2022. Booth, D.B, Troost, K.A., and Wisher, A. P. 2007. “Geologic Map of King County.” Idriss, I.M. and Boulanger, R.W. (2008), “Soil Liquefaction During Earthquakes.” Earthquake Engineering Research Institute (EERI), Monograph MNO-12. International Code Council, 2018 International Building Code. Mullineaux, D.R. 1965, United States Geologic Survey, Geologic Quadrangle, “Geologic Map of the Renton Quadrangle, King County, Washington.” Tokimatsu, K. and Seed, H.B. (1987). “Evaluation of Settlement in Sands due to Earthquake Shaking,” Journal of Geotechnical Engineering, ASCE, Vol. 113, No. 8, August 1987, pp. 861-878. Washington State Department of Transportation, 2022, “Standard Specifications for Road, Bridge and Municipal Construction.” Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 NE7thPl SE116thSt NE6thSt NE6thSt 156thAveSE NE10thSt NE10thSt NE17thSt NE8thSt HoquiamAveNE 155thAveSE SE128thSt 138thAveSE 148thAveSE NESunset Blvd CoalfieldPark MayValleyPark EastRenton Highlands 160thAveSE S E144thSt SE144thSt SE145thPl SE2ndStSE2ndPl NE2ndSt SE142ndSt NE3rdSt SE141st St 156thAveSE MaplewoodPark MaplewoodGolf Course RonRegisPark MayCreek SEMayValleyRd SE121stPl 169t h Ave SE 171st Pl SE SE128thSt 164thAveSE S E Renton-IssaquahRd MayValley 164thNatural Area Coalfield SE134thSt SE140thSt SE144thSt 175thAveSE PatriotWaySE Maplewood HeightsPark SITE Vicinity Map Figure 1 Renton Regional Fire Authority,Station 16 Replacement,Renton, Washington 3 2 AlpineLakes Wilderness Everett Kent Seattle 2,000 2,0000 Feet Data Source: ESRI Notes: 1. The locations of all features shown are approximate.2. This drawing is for information purposes. It is intended to assist inshowing features discussed in an attached document. GeoEngineers, Inc.cannot guarantee the accuracy and content of electronic files. The masterfile is stored by GeoEngineers, Inc. and will serve as the official record ofthis communication. Projection: NAD 1983 StatePlane Washington North FIPS 4601 Feet\\g e o e n g i n e e r s . c o m \ W A N \ P r o j e c t s \ 2 6 \ 2 6 0 1 6 0 0 1 \ G I S \ M X D \ 2 6 0 1 6 0 0 1 0 0 _ F 0 1 _ V M \ 2 6 0 1 6 0 0 1 0 0 _ F 0 1 _ V M . a p r x \ V i c i n i t y M a p D a t e E x p o r t e d : 0 7 / 1 1 / 2 2 b y t b y r d Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 GEI-1 GEI-2 GEI-3 GEI-4 GEI-7 GEI-8 GEI-6 GEI-5 GEI-9 GEI-10 Figure 2 Renton Regional Fire Authority, Station 16 Replacement, Renton, Washington Site Plan \\ g e o e n g i n e e r s . c o m \ W A N \ P r o j e c t s \ 2 6 \ 2 6 0 1 6 0 0 1 \ C A D \ 0 0 \ 2 6 0 1 6 0 0 1 0 0 _ F 0 2 _ S i t e P l a n . d w g F0 2 D a t e E x p o r t e d : 8/ 2 / 2 0 2 2 3 : 2 3 P M - b y TJ B y r d W E N S Notes: 1.The locations of all features shown are approximate. 2.This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. GeoEngineers, Inc. cannot guarantee the accuracy and content of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication. Data Source: Background data from TCA dated 03/17/22. Projection: WA State Plane, North Zone, NAD83, US Foot Feet 0 Legend 100 100 GEI-1 Boring by GeoEngineers, Inc., 2022 SE 128th St 15 8 t h A v e S E 16 0 t h A v e S E Site Boundary Proposed Fire Station Pr o p o s e d Ma i n t e n a n c e Ga r a g e Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 APPENDIX A Field Explorations Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 August 5, 2022 | Page A-1 File No. 26016-001-00 APPENDIX A FIELD EXPLORATIONS Subsurface soil and groundwater conditions at the site were evaluated by drilling ten geotechnical hollow-stem auger borings (GEI-1 through GEI-10). The borings were completed to depths of about 10½ to 50½ feet below existing site grade. The borings were completed by Holocene Acquisition Company, LLC on June 20 through 22, 2022. The approximate locations of the explorations are shown in the Site Plan, Figure 2. Borings The borings were completed using track-mounted, continuous-flight, hollow-stem auger drilling equipment. The borings were continuously monitored by a geotechnical engineer from our firm who examined and classified the soils encountered, obtained representative soil samples, observed groundwater conditions and prepared a detailed log of each exploration. The soils encountered in the borings were generally sampled at 2½- and 5-foot vertical intervals with a 2-inch outside-diameter split-barrel standard penetration test (SPT) sampler. The disturbed samples were obtained by driving the sampler 18 inches into the soil with a 140-pound automatic hammer free-falling 30 inches. The number of blows required for each 6 inches of penetration was recorded. The blow count (“N-value”) of the soil was calculated as the number of blows required for the final 12 inches of penetration. This resistance, or N-value, provides a measure of the relative density of granular soils and the relative consistency of cohesive soils. Where very dense soil conditions precluded driving the full 18 inches, the penetration resistance for the partial penetration was entered on the logs. The blow counts are shown on the boring logs at the respective sample depths. Soils encountered in the borings were visually classified in general accordance with the classification system described in Figure A-1. A key to the boring log symbols is also presented in Figure A-1. The logs of the borings are presented in Figures A-2 through A-11. The boring logs are based on our interpretation of the field and laboratory data and indicate the various types of soils and groundwater conditions encountered. The logs also indicate the depths at which these soils or their characteristics change, although the change may actually be gradual. If the change occurred between samples, it was interpreted. The densities noted in the boring logs are based on the blow count data obtained in the borings and judgment based on the conditions encountered. Observations of groundwater conditions were made during drilling. The groundwater conditions encountered during drilling are presented in the boring logs. Groundwater conditions observed during drilling represent a short-term condition and may or may not be representative of the long-term groundwater conditions at the site. Groundwater conditions observed during drilling should be considered approximate. Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 Measured groundwater level in exploration,well, or piezometer Measured free product in well or piezometer Distinct contact between soil strata Approximate contact between soil strata Contact between geologic units SYMBOLS TYPICAL DESCRIPTIONS GW GP SW SP SM FINEGRAINED SOILS SILTS ANDCLAYS NOTE: Multiple symbols are used to indicate borderline or dual soil classifications MORE THAN 50%RETAINED ONNO. 200 SIEVE MORE THAN 50%PASSINGNO. 200 SIEVE GRAVEL ANDGRAVELLYSOILS SC LIQUID LIMITLESS THAN 50 (APPRECIABLE AMOUNTOF FINES) (APPRECIABLE AMOUNTOF FINES) COARSEGRAINEDSOILS MAJOR DIVISIONS GRAPH LETTER GM GC ML CL OL SILTS AND CLAYS SANDS WITHFINES SANDANDSANDY SOILS MH CH OH PT (LITTLE OR NO FINES) CLEAN SANDS GRAVELS WITHFINES CLEAN GRAVELS (LITTLE OR NO FINES) WELL-GRADED GRAVELS, GRAVEL -SAND MIXTURES CLAYEY GRAVELS, GRAVEL - SAND -CLAY MIXTURES WELL-GRADED SANDS, GRAVELLYSANDS POORLY-GRADED SANDS, GRAVELLYSAND SILTY SANDS, SAND - SILT MIXTURES CLAYEY SANDS, SAND - CLAYMIXTURES INORGANIC SILTS, ROCK FLOUR,CLAYEY SILTS WITH SLIGHTPLASTICITY INORGANIC CLAYS OF LOW TOMEDIUM PLASTICITY, GRAVELLYCLAYS, SANDY CLAYS, SILTY CLAYS,LEAN CLAYS ORGANIC SILTS AND ORGANIC SILTYCLAYS OF LOW PLASTICITY INORGANIC SILTS, MICACEOUS ORDIATOMACEOUS SILTY SOILS INORGANIC CLAYS OF HIGHPLASTICITY ORGANIC CLAYS AND SILTS OFMEDIUM TO HIGH PLASTICITY PEAT, HUMUS, SWAMP SOILS WITHHIGH ORGANIC CONTENTSHIGHLY ORGANIC SOILS SOIL CLASSIFICATION CHART MORE THAN 50%OF COARSEFRACTION RETAINEDON NO. 4 SIEVE MORE THAN 50%OF COARSEFRACTION PASSINGON NO. 4 SIEVE SILTY GRAVELS, GRAVEL - SAND -SILT MIXTURES POORLY-GRADED GRAVELS,GRAVEL - SAND MIXTURES LIQUID LIMIT GREATERTHAN 50 Continuous Coring Bulk or grab Direct-Push Piston Shelby tube Standard Penetration Test (SPT) Contact between soil of the same geologicunit Material Description Contact Graphic Log Contact NOTE: The reader must refer to the discussion in the report text and the logs of explorations for a proper understanding of subsurface conditions.Descriptions on the logs apply only at the specific exploration locations and at the time the explorations were made; they are not warranted to berepresentative of subsurface conditions at other locations or times. Groundwater Contact Blowcount is recorded for driven samplers as the number ofblows required to advance sampler 12 inches (or distance noted).See exploration log for hammer weight and drop. "P" indicates sampler pushed using the weight of the drill rig. "WOH" indicates sampler pushed using the weight of thehammer. Key to Exploration Logs Figure A-1 Sampler Symbol Descriptions ADDITIONAL MATERIAL SYMBOLS SYMBOLS Asphalt Concrete Cement Concrete Crushed Rock/Quarry Spalls Topsoil GRAPH LETTER AC CC SOD Sod/Forest Duff CR DESCRIPTIONS TYPICAL TS No Visible SheenSlight SheenModerate SheenHeavy Sheen Laboratory / Field Tests 2.4-inch I.D. split barrel / Dames & Moore (D&M) %F%GALCACPCSDDDSHAMCMDMohsOCPMPIPLPPSATXUCUUVS Sheen Classification NSSSMSHS Percent finesPercent gravelAtterberg limitsChemical analysisLaboratory compaction testConsolidation testDry densityDirect shearHydrometer analysisMoisture contentMoisture content and dry densityMohs hardness scaleOrganic contentPermeability or hydraulic conductivityPlasticity indexPoint lead testPocket penetrometerSieve analysisTriaxial compressionUnconfined compressionUnconsolidated undrained triaxial compressionVane shear Rev 01/2022 Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 24 18 18 31 30 41 1 2%F 3SA 4SA 5 6 6 6 12 12 12 18 9 12 52 55 CR SM SM SM Approximately 6 inches of crushed gravel mixed withdark brown silty fine to medium sand with organicmatter (loose, moist) (existing gravel driveway) Brown silty fine sand with gravel and organic matter(loose, moist) (fill) Brownish gray silty fine to medium sand withoccasional gravel, iron oxide staining (loose, moist)(weathered glacial till) Gray silty fine to medium sand with occasional gravel(very dense, moist) (glacial till) Notes: 11.5 BA CC Holocene AcquisitionCompany, LLC Hollow-stem Auger Diedrich D70 TurboDrillingEquipmentAutohammer140 (lbs) / 30 (in) Drop WA State Plane NorthNAD83 (feet)1320100180715 535NAVD88 Easting (X)Northing (Y) Start TotalDepth (ft) Logged By Checked By End Surface Elevation (ft)Vertical Datum Drilled HammerData SystemDatum Driller DrillingMethod Groundwater not observed at time of exploration 6/21/20226/21/2022 Note: See Figure A-1 for explanation of symbols.Coordinates Data Source: Horizontal approximated based on Aerial Imagery. Vertical approximated based on Aerial Imagery. Sheet 1 of 1Project Number: Project Location: Project: Renton, Washington 26016-001-00 Log of Boring GEI-1 Renton Regional Fire Authority, Station 16 Replacement Figure A-2 Da t e : 8 / 2 / 2 2 P a t h : P : \ 2 6 \ 2 6 0 1 6 0 0 1 \ G I N T \ 2 6 0 1 6 0 0 1 0 0 . G P J D B L i b r a r y / L i b r a r y : G E O E N G I N E E R S L I B R A R Y _ D F _ S T D _ U S _ J U N E _ 2 0 1 7 . G L B / G E I 8 _ G E O T E C H _ S T A N D A R D _ % F _ N O _ G W REMARKS Mo i s t u r e Co n t e n t ( % ) Fi n e s Co n t e n t ( % ) FIELD DATA Sa m p l e N a m e Te s t i n g Re c o v e r e d ( i n ) In t e r v a l Bl o w s / f o o t Co l l e c t e d S a m p l e De p t h ( f e e t ) 0 5 10 Gr a p h i c L o g Gr o u p Cl a s s i f i c a t i o n El e v a t i o n ( f e e t ) 530 525 MATERIALDESCRIPTION Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 9 37 1 2 3 4%F 5 6 6 6 12 12 18 18 6 27 50 50 CR SM SM/TS SM SM SM Approximately 6 inches of crushed gravel mixed withdark brown silty fine to medium sand with organicmatter (loose, moist) (existing gravel driveway) Brown silty fine to medium sand with occasional gravel(loose, wet) (fill) Dark brown silty fine to medium sand with occasionalgravel and organic matter (loose, moist) (fill/relicttopsoil) Brownish gray silty fine to medium sand withoccasional gravel, iron oxide staining (loose, moist)(weathered glacial till) Brown silty fine to medium sand with gravel (mediumdense, moist) Brown silty fine to medium sand with gravel (dense,moist) (glacial till) Notes: 11.5 BA CC Holocene AcquisitionCompany, LLC Hollow-stem Auger Diedrich D70 TurboDrillingEquipmentAutohammer140 (lbs) / 30 (in) Drop WA State Plane NorthNAD83 (feet)1320096180541 542NAVD88 Easting (X)Northing (Y) Start TotalDepth (ft) Logged By Checked By End Surface Elevation (ft)Vertical Datum Drilled HammerData SystemDatum Driller DrillingMethod Groundwater not observed at time of exploration 6/21/20226/21/2022 Note: See Figure A-1 for explanation of symbols.Coordinates Data Source: Horizontal approximated based on Aerial Imagery. Vertical approximated based on Aerial Imagery. Sheet 1 of 1Project Number: Project Location: Project: Renton, Washington 26016-001-00 Log of Boring GEI-2 Renton Regional Fire Authority, Station 16 Replacement Figure A-3 Da t e : 8 / 2 / 2 2 P a t h : P : \ 2 6 \ 2 6 0 1 6 0 0 1 \ G I N T \ 2 6 0 1 6 0 0 1 0 0 . G P J D B L i b r a r y / L i b r a r y : G E O E N G I N E E R S L I B R A R Y _ D F _ S T D _ U S _ J U N E _ 2 0 1 7 . G L B / G E I 8 _ G E O T E C H _ S T A N D A R D _ % F _ N O _ G W REMARKS Mo i s t u r e Co n t e n t ( % ) Fi n e s Co n t e n t ( % ) FIELD DATA Sa m p l e N a m e Te s t i n g Re c o v e r e d ( i n ) In t e r v a l Bl o w s / f o o t Co l l e c t e d S a m p l e De p t h ( f e e t ) 0 5 10 Gr a p h i c L o g Gr o u p Cl a s s i f i c a t i o n El e v a t i o n ( f e e t ) 540 53 5 MATERIALDESCRIPTION Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 19 19 34 1 2%F 3MC 4 5 6 6 6 12 18 12 12 20 56 50/6" 50/6" CR SM SM SM Approximately 6 inches of crushed gravel mixed withdark brown silty fine to mediums and with organicmatter (loose, moist) (existing gravel driveway) Dark brown silty fine to medium sand with occasionalgravel (loose, moist to wet) (fill) Brownish gray silty fine to medium sand withoccasional gravel, iron oxide staining (mediumdense, moist) (weathered glacial till) Gray silty fine to medium sand with gravel (very dense,moist) (glacial till) Grades with higher gravel content Notes: 11 BA CC Holocene AcquisitionCompany, LLC Hollow-stem Auger Diedrich D70 TurboDrillingEquipmentAutohammer140 (lbs) / 30 (in) Drop WA State Plane NorthNAD83 (feet)1320097180410 546NAVD88 Easting (X)Northing (Y) Start TotalDepth (ft) Logged By Checked By End Surface Elevation (ft)Vertical Datum Drilled HammerData SystemDatum Driller DrillingMethod Groundwater not observed at time of exploration 6/22/20226/22/2022 Note: See Figure A-1 for explanation of symbols.Coordinates Data Source: Horizontal approximated based on Aerial Imagery. Vertical approximated based on Aerial Imagery. Sheet 1 of 1Project Number: Project Location: Project: Renton, Washington 26016-001-00 Log of Boring GEI-3 Renton Regional Fire Authority, Station 16 Replacement Figure A-4 Da t e : 8 / 2 / 2 2 P a t h : P : \ 2 6 \ 2 6 0 1 6 0 0 1 \ G I N T \ 2 6 0 1 6 0 0 1 0 0 . G P J D B L i b r a r y / L i b r a r y : G E O E N G I N E E R S L I B R A R Y _ D F _ S T D _ U S _ J U N E _ 2 0 1 7 . G L B / G E I 8 _ G E O T E C H _ S T A N D A R D _ % F _ N O _ G W REMARKS Mo i s t u r e Co n t e n t ( % ) Fi n e s Co n t e n t ( % ) FIELD DATA Sa m p l e N a m e Te s t i n g Re c o v e r e d ( i n ) In t e r v a l Bl o w s / f o o t Co l l e c t e d S a m p l e De p t h ( f e e t ) 0 5 10 Gr a p h i c L o g Gr o u p Cl a s s i f i c a t i o n El e v a t i o n ( f e e t ) 545 540 535 MATERIALDESCRIPTION Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 12 30 1 2 3SA 4 5 6 6 6 18 18 12 6 36 43 83/11" 50/6" CR SM SM SM SM SM SM Approximately 6 inches of crushed gravel mixed withdark brown silty fine sand with organic matter(loose, moist) (existing gravel driveway) Dark brown silty fine sand with gravel and organicmatter (loose, moist) (fill) Brown silty fine to medium sand with occasional graveland trace organic matter (loose, moist) Gray silty fine to medium sand with occasional gravel(dense, moist) (weathered glacial till) Gray silty fine to medium sand with gravel (dense,moist) (glacial till) Gray silty fine to medium sand with gravel (very dense,moist to wet) Gray silty fine to medium sand with occasional gravel(very dense, moist) Notes: 10.5 BA CC Holocene AcquisitionCompany, LLC Hollow-stem Auger Diedrich D70 TurboDrillingEquipmentAutohammer140 (lbs) / 30 (in) Drop WA State Plane NorthNAD83 (feet)1320009180305 551NAVD88 Easting (X)Northing (Y) Start TotalDepth (ft) Logged By Checked By End Surface Elevation (ft)Vertical Datum Drilled HammerData SystemDatum Driller DrillingMethod Groundwater not observed at time of exploration 6/22/20226/22/2022 Note: See Figure A-1 for explanation of symbols.Coordinates Data Source: Horizontal approximated based on Aerial Imagery. Vertical approximated based on Aerial Imagery. Sheet 1 of 1Project Number: Project Location: Project: Renton, Washington 26016-001-00 Log of Boring GEI-4 Renton Regional Fire Authority, Station 16 Replacement Figure A-5 Da t e : 8 / 2 / 2 2 P a t h : P : \ 2 6 \ 2 6 0 1 6 0 0 1 \ G I N T \ 2 6 0 1 6 0 0 1 0 0 . G P J D B L i b r a r y / L i b r a r y : G E O E N G I N E E R S L I B R A R Y _ D F _ S T D _ U S _ J U N E _ 2 0 1 7 . G L B / G E I 8 _ G E O T E C H _ S T A N D A R D _ % F _ N O _ G W REMARKS Mo i s t u r e Co n t e n t ( % ) Fi n e s Co n t e n t ( % ) FIELD DATA Sa m p l e N a m e Te s t i n g Re c o v e r e d ( i n ) In t e r v a l Bl o w s / f o o t Co l l e c t e d S a m p l e De p t h ( f e e t ) 0 5 10 Gr a p h i c L o g Gr o u p Cl a s s i f i c a t i o n El e v a t i o n ( f e e t ) 550 545 MATERIALDESCRIPTION Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 18 12 10 41 39 1 2 3MC 4%F 5%F 6 7 8 9 10 6 6 18 18 16 18 12 6 6 11 14 46 90/10" 75 50/6" 50/2" 50/6" 50/5" CR ML SM SM SM SM Approximately 6 inches of crushed gravel mixed withdark brown sandy silt with organic matter (loose,moist) (existing gravel driveway) Brown sandy silt with occasional gravel and organicmatter (soft, moist to wet) (fill) Brown silty fine to medium sand with occasional graveland trace organic matter (loose, wet) Grayish brown silty fine to medium sand with gravel(medium dense, moist) (weathered glacial till) Brownish gray silty fine to medium sand with gravel(dense, moist) Gray silty fine to medium sand with gravel (very dense,moist) (glacial till) Grades to with occasional cobbles Grades to with lower fines content Notes: 31 BA CC Holocene AcquisitionCompany, LLC Hollow-stem Auger Diedrich D70 TurboDrillingEquipmentAutohammer140 (lbs) / 30 (in) Drop WA State Plane NorthNAD83 (feet)1320005180676 542NAVD88 Easting (X)Northing (Y) Start TotalDepth (ft) Logged By Checked By End Surface Elevation (ft)Vertical Datum Drilled HammerData SystemDatum Driller DrillingMethod Groundwater not observed at time of exploration 6/21/20226/21/2022 Note: See Figure A-1 for explanation of symbols.Coordinates Data Source: Horizontal approximated based on Aerial Imagery. Vertical approximated based on Aerial Imagery. Sheet 1 of 1Project Number: Project Location: Project: Renton, Washington 26016-001-00 Log of Boring GEI-5 Renton Regional Fire Authority, Station 16 Replacement Figure A-6 Da t e : 8 / 2 / 2 2 P a t h : P : \ 2 6 \ 2 6 0 1 6 0 0 1 \ G I N T \ 2 6 0 1 6 0 0 1 0 0 . G P J D B L i b r a r y / L i b r a r y : G E O E N G I N E E R S L I B R A R Y _ D F _ S T D _ U S _ J U N E _ 2 0 1 7 . G L B / G E I 8 _ G E O T E C H _ S T A N D A R D _ % F _ N O _ G W REMARKS Mo i s t u r e Co n t e n t ( % ) Fi n e s Co n t e n t ( % ) FIELD DATA Sa m p l e N a m e Te s t i n g Re c o v e r e d ( i n ) In t e r v a l Bl o w s / f o o t Co l l e c t e d S a m p l e De p t h ( f e e t ) 0 5 10 15 20 25 30 Gr a p h i c L o g Gr o u p Cl a s s i f i c a t i o n El e v a t i o n ( f e e t ) 540 53 5 530 525 520 515 MATERIALDESCRIPTION Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 No recovery with SPT sampler, followed withCalifornia sampler55 blows/foot for SPT No recovery with SPT sampler, followed withCalifornia sampler60 blows/foot fot SPT 11 38 1 2 3 4 5SA 6 7 8 9 10 6 6 6 4 18 18 0 10 5 6 12 22 40 62 50/3" 50/4" 50/5" 50/6" TS ML TS SM SM SM SM Approximately 6 inches of topsoil/sod Brown sandy silt with occasional gravel and organicmatter (soft, wet) (fill) Dark brown to black relict topsoil/sod (soft, moist) Brown silty fine to medium sand with occasionalgravel, iron oxide staining (medium dense, moist)(weathered glacial till) Brown silty fine to medium sand with gravel andcobbles (very dense, moist) (glacial till) Grayish brown silty fine to medium sand with graveland cobbles (very dense, moist) Grayish silty fine to medium sand with gravel (verydense, moist) Grades to with lower fines content Grades to with higher fines content Notes: 30.5 BA CC Holocene AcquisitionCompany, LLC Hollow-stem Auger Diedrich D70 TurboDrillingEquipmentAutohammer140 (lbs) / 30 (in) Drop WA State Plane NorthNAD83 (feet)1320093180656 537NAVD88 Easting (X)Northing (Y) Start TotalDepth (ft) Logged By Checked By End Surface Elevation (ft)Vertical Datum Drilled HammerData SystemDatum Driller DrillingMethod Groundwater not observed at time of exploration 6/21/20226/21/2022 Note: See Figure A-1 for explanation of symbols.Coordinates Data Source: Horizontal approximated based on Aerial Imagery. Vertical approximated based on Aerial Imagery. Sheet 1 of 1Project Number: Project Location: Project: Renton, Washington 26016-001-00 Log of Boring GEI-6 Renton Regional Fire Authority, Station 16 Replacement Figure A-7 Da t e : 8 / 2 / 2 2 P a t h : P : \ 2 6 \ 2 6 0 1 6 0 0 1 \ G I N T \ 2 6 0 1 6 0 0 1 0 0 . G P J D B L i b r a r y / L i b r a r y : G E O E N G I N E E R S L I B R A R Y _ D F _ S T D _ U S _ J U N E _ 2 0 1 7 . G L B / G E I 8 _ G E O T E C H _ S T A N D A R D _ % F _ N O _ G W REMARKS Mo i s t u r e Co n t e n t ( % ) Fi n e s Co n t e n t ( % ) FIELD DATA Sa m p l e N a m e Te s t i n g Re c o v e r e d ( i n ) In t e r v a l Bl o w s / f o o t Co l l e c t e d S a m p l e De p t h ( f e e t ) 0 5 10 15 20 25 30 Gr a p h i c L o g Gr o u p Cl a s s i f i c a t i o n El e v a t i o n ( f e e t ) 535 53 0 525 520 515 510 MATERIALDESCRIPTION Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 26 18 42 1 2 3MC 4%F 5 6 7 8 9 10 6 6 18 18 18 18 12 6 5 6 30 17 58 68 50/6" 50/6" 50/5" 50/6" TS SM SM SM SM SM Black topsoil with occasional gravel and abundantorganic matter Dark brown silty fine to medium sand with occasionalgravel and organic matter (loose, moist to wet) Brown silty fine to medium sand with occasional graveland trace organic matter, iron oxide staining(dense, moist to wet) (weathered glacial till) Grayish brown silty fine to medium sand withoccasional gravel, iron oxide staining (mediumdense, moist) Brown silty fine to medium sand with occasional gravel(very dense, moist) (glacial till) Brownish gray silty fine to medium sand with gravel(very dense, moist) Grades to with lower fines content and higher gravelcontent Becomes gray Notes: 30.5 BA CC Holocene AcquisitionCompany, LLC Hollow-stem Auger Diedrich D70 TurboDrillingEquipmentAutohammer140 (lbs) / 30 (in) Drop WA State Plane NorthNAD83 (feet)1320123180364 546NAVD88 Easting (X)Northing (Y) Start TotalDepth (ft) Logged By Checked By End Surface Elevation (ft)Vertical Datum Drilled HammerData SystemDatum Driller DrillingMethod Groundwater not observed at time of exploration 6/22/20226/22/2022 Note: See Figure A-1 for explanation of symbols.Coordinates Data Source: Horizontal approximated based on Aerial Imagery. Vertical approximated based on Aerial Imagery. Sheet 1 of 1Project Number: Project Location: Project: Renton, Washington 26016-001-00 Log of Boring GEI-7 Renton Regional Fire Authority, Station 16 Replacement Figure A-8 Da t e : 8 / 2 / 2 2 P a t h : P : \ 2 6 \ 2 6 0 1 6 0 0 1 \ G I N T \ 2 6 0 1 6 0 0 1 0 0 . G P J D B L i b r a r y / L i b r a r y : G E O E N G I N E E R S L I B R A R Y _ D F _ S T D _ U S _ J U N E _ 2 0 1 7 . G L B / G E I 8 _ G E O T E C H _ S T A N D A R D _ % F _ N O _ G W REMARKS Mo i s t u r e Co n t e n t ( % ) Fi n e s Co n t e n t ( % ) FIELD DATA Sa m p l e N a m e Te s t i n g Re c o v e r e d ( i n ) In t e r v a l Bl o w s / f o o t Co l l e c t e d S a m p l e De p t h ( f e e t ) 0 5 10 15 20 25 30 Gr a p h i c L o g Gr o u p Cl a s s i f i c a t i o n El e v a t i o n ( f e e t ) 545 540 535 530 525 520 MATERIALDESCRIPTION Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 No recovery with SPT sampler, followed withCalifornia sampler50/6" blows/foot for SPT 23 10 32 1 2 3MC 4 5%F 6 7 8 9 10 6 6 12 16 12 6 6 2 1 0 12 50/6" 50/6" 50/6" 50/6" 50/6" 50/4" TS SM SM SM SM SM Black topsoil with occasional gravel and abundantorganic matter Brown silty fine to medium sand with occasionalgravel, iron oxide staining (very loose, wet) (fill?) Grayish brown silty fine to medium sand with tracegravel, iron oxide staining (medium dense, moist towet) (weathered glacial till) Brownish gray silty fine to medium sand with tracegravel (very dense, moist) Brownish gray silty fine to medium sand with gravel(very dense, moist) Gray silty fine to medium sand with occasional gravel(very dense, moist) Notes: 31 BA CC Holocene AcquisitionCompany, LLC Hollow-stem Auger Diedrich D70 TurboDrillingEquipmentAutohammer140 (lbs) / 30 (in) Drop WA State Plane NorthNAD83 (feet)1320122180318 549NAVD88 Easting (X)Northing (Y) Start TotalDepth (ft) Logged By Checked By End Surface Elevation (ft)Vertical Datum Drilled HammerData SystemDatum Driller DrillingMethod Groundwater not observed at time of exploration 6/22/20226/22/2022 Note: See Figure A-1 for explanation of symbols.Coordinates Data Source: Horizontal approximated based on Aerial Imagery. Vertical approximated based on Aerial Imagery. Sheet 1 of 1Project Number: Project Location: Project: Renton, Washington 26016-001-00 Log of Boring GEI-8 Renton Regional Fire Authority, Station 16 Replacement Figure A-9 Da t e : 8 / 2 / 2 2 P a t h : P : \ 2 6 \ 2 6 0 1 6 0 0 1 \ G I N T \ 2 6 0 1 6 0 0 1 0 0 . G P J D B L i b r a r y / L i b r a r y : G E O E N G I N E E R S L I B R A R Y _ D F _ S T D _ U S _ J U N E _ 2 0 1 7 . G L B / G E I 8 _ G E O T E C H _ S T A N D A R D _ % F _ N O _ G W REMARKS Mo i s t u r e Co n t e n t ( % ) Fi n e s Co n t e n t ( % ) FIELD DATA Sa m p l e N a m e Te s t i n g Re c o v e r e d ( i n ) In t e r v a l Bl o w s / f o o t Co l l e c t e d S a m p l e De p t h ( f e e t ) 0 5 10 15 20 25 30 Gr a p h i c L o g Gr o u p Cl a s s i f i c a t i o n El e v a t i o n ( f e e t ) 54 5 540 535 530 525 520 MATERIALDESCRIPTION Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 Perched groundwater observed at approximately10 feet below existing ground surface 26 20 15 30 1 2 3MC 4 5 6MC 7SA 8 9 10 6 6 18 3 3 9 5 5 10 5 11 11 44 70 50/5" 50/4" 50/4" 50/5" SOD ML SM SM SM SM SM SM Approximately 4 inches of topsoil/sod Brown sandy silt with occasional gravel (very soft, wet)(fill) Brown silty fine to medium sand with occasional gravel(very loose, wet) Brown silty fine to medium sand with organic matter(medium dense, wet) Dark brown silty fine to medium sand with occasionalgravel and organic matter (medium dense, wet) Brown silty fine to medium sand with occasional gravel(dense, wet) (weathered glacial till) Brown silty fine to medium sand with gravel (verydense, wet) (glacial till) Brown silty fine to medium sand with gravel (verydense, moist) Becomes gray Grades to with lower fines content Notes: 50.5 BA CC Holocene AcquisitionCompany, LLC Hollow-stem Auger Diedrich D70 TurboDrillingEquipmentAutohammer140 (lbs) / 30 (in) Drop WA State Plane NorthNAD83 (feet)1320039180602 540NAVD88 Easting (X)Northing (Y) Start TotalDepth (ft) Logged By Checked By End Surface Elevation (ft)Vertical Datum Drilled HammerData SystemDatum Driller DrillingMethod See "Remarks" section for groundwater observed 6/20/20226/20/2022 Note: See Figure A-1 for explanation of symbols.Coordinates Data Source: Horizontal approximated based on Aerial Imagery. Vertical approximated based on Aerial Imagery. Sheet 1 of 2Project Number: Project Location: Project: Renton, Washington 26016-001-00 Log of Boring GEI-9 Renton Regional Fire Authority, Station 16 Replacement Figure A-10 Da t e : 8 / 2 / 2 2 P a t h : P : \ 2 6 \ 2 6 0 1 6 0 0 1 \ G I N T \ 2 6 0 1 6 0 0 1 0 0 . G P J D B L i b r a r y / L i b r a r y : G E O E N G I N E E R S L I B R A R Y _ D F _ S T D _ U S _ J U N E _ 2 0 1 7 . G L B / G E I 8 _ G E O T E C H _ S T A N D A R D _ % F _ N O _ G W REMARKS Mo i s t u r e Co n t e n t ( % ) Fi n e s Co n t e n t ( % ) FIELD DATA Sa m p l e N a m e Te s t i n g Re c o v e r e d ( i n ) In t e r v a l Bl o w s / f o o t Co l l e c t e d S a m p l e De p t h ( f e e t ) 0 5 10 15 20 25 30 35 Gr a p h i c L o g Gr o u p Cl a s s i f i c a t i o n El e v a t i o n ( f e e t ) 535 530 525 52 0 515 510 505 MATERIALDESCRIPTION Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 11 12 13 14 6 4 6 6 50/6" 50/4" 50/6" 50/6" Sheet 2 of 2Project Number: Project Location: Project: Renton, Washington 26016-001-00 Log of Boring GEI-9 (continued) Renton Regional Fire Authority, Station 16 Replacement Figure A-10 Da t e : 8 / 2 / 2 2 P a t h : P : \ 2 6 \ 2 6 0 1 6 0 0 1 \ G I N T \ 2 6 0 1 6 0 0 1 0 0 . G P J D B L i b r a r y / L i b r a r y : G E O E N G I N E E R S L I B R A R Y _ D F _ S T D _ U S _ J U N E _ 2 0 1 7 . G L B / G E I 8 _ G E O T E C H _ S T A N D A R D _ % F _ N O _ G W REMARKS Mo i s t u r e Co n t e n t ( % ) Fi n e s Co n t e n t ( % ) FIELD DATA Sa m p l e N a m e Te s t i n g Re c o v e r e d ( i n ) In t e r v a l Bl o w s / f o o t Co l l e c t e d S a m p l e De p t h ( f e e t ) 35 40 45 50 Gr a p h i c L o g Gr o u p Cl a s s i f i c a t i o n El e v a t i o n ( f e e t ) 500 495 49 0 MATERIALDESCRIPTION Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 23 17 15 36 34 38 1 2%F 3SA 4 5%F 6 7 8 9 10 6 6 18 17 17 12 12 4 6 5 23 79/11" 79/11" 50/6" 50/6" 50/4" 50/6" 50/5" CR ML SM SM SM SM SM SM SM Approximately 6 inches of crushed gravel mixed withdark brown sandy silt with organic matter (loose,moist) (existing gravel driveway) Dark brown sandy silt with occasional gravel andorganic matter (soft, moist to wet)Becomes brown Grayish brown silty fine to medium sand with gravel,iron oxide staining (medium dense, moist)(weathered glacial till) Brown silty fine to coarse sand with gravel (very dense,moist) (glacial till) Grayish brown silty fine to coarse sand with gravel(very dense, moist) Brownish gray silty fine to medium sand with gravel(very dense, moist) Gray silty fine to medium sand with occasional gravel(very dense, moist) Gray silty fine to medium sand with gravel and cobbles(very dense, moist) Gray silty fine to medium sand with occasional gravel(very dense, wet) Notes: 40.5 BA CC Holocene AcquisitionCompany, LLC Hollow-stem Auger Diedrich D70 TurboDrillingEquipmentAutohammer140 (lbs) / 30 (in) Drop WA State Plane NorthNAD83 (feet)1320119180248 548NAVD88 Easting (X)Northing (Y) Start TotalDepth (ft) Logged By Checked By End Surface Elevation (ft)Vertical Datum Drilled HammerData SystemDatum Driller DrillingMethod Groundwater not observed at time of exploration 6/20/20226/20/2022 Note: See Figure A-1 for explanation of symbols.Coordinates Data Source: Horizontal approximated based on Aerial Imagery. Vertical approximated based on Aerial Imagery. Sheet 1 of 2Project Number: Project Location: Project: Renton, Washington 26016-001-00 Log of Boring GEI-10 Renton Regional Fire Authority, Station 16 Replacement Figure A-11 Da t e : 8 / 2 / 2 2 P a t h : P : \ 2 6 \ 2 6 0 1 6 0 0 1 \ G I N T \ 2 6 0 1 6 0 0 1 0 0 . G P J D B L i b r a r y / L i b r a r y : G E O E N G I N E E R S L I B R A R Y _ D F _ S T D _ U S _ J U N E _ 2 0 1 7 . G L B / G E I 8 _ G E O T E C H _ S T A N D A R D _ % F _ N O _ G W REMARKS Mo i s t u r e Co n t e n t ( % ) Fi n e s Co n t e n t ( % ) FIELD DATA Sa m p l e N a m e Te s t i n g Re c o v e r e d ( i n ) In t e r v a l Bl o w s / f o o t Co l l e c t e d S a m p l e De p t h ( f e e t ) 0 5 10 15 20 25 30 35 Gr a p h i c L o g Gr o u p Cl a s s i f i c a t i o n El e v a t i o n ( f e e t ) 545 540 535 530 52 5 520 515 MATERIALDESCRIPTION Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 11 12 2 5 50/5" 50/5" SM Dark gray silty fine to coarse sand with gravel andcobbles (very dense, moist to wet) Boring terminated at shallower depth than planneddue to refusal Sheet 2 of 2Project Number: Project Location: Project: Renton, Washington 26016-001-00 Log of Boring GEI-10 (continued) Renton Regional Fire Authority, Station 16 Replacement Figure A-11 Da t e : 8 / 2 / 2 2 P a t h : P : \ 2 6 \ 2 6 0 1 6 0 0 1 \ G I N T \ 2 6 0 1 6 0 0 1 0 0 . G P J D B L i b r a r y / L i b r a r y : G E O E N G I N E E R S L I B R A R Y _ D F _ S T D _ U S _ J U N E _ 2 0 1 7 . G L B / G E I 8 _ G E O T E C H _ S T A N D A R D _ % F _ N O _ G W REMARKS Mo i s t u r e Co n t e n t ( % ) Fi n e s Co n t e n t ( % ) FIELD DATA Sa m p l e N a m e Te s t i n g Re c o v e r e d ( i n ) In t e r v a l Bl o w s / f o o t Co l l e c t e d S a m p l e De p t h ( f e e t ) 35 40 Gr a p h i c L o g Gr o u p Cl a s s i f i c a t i o n El e v a t i o n ( f e e t ) 510 MATERIALDESCRIPTION Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 APPENDIX B Laboratory Testing Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 August 5, 2022 | Page B-1 File No. 26016-001-00 APPENDIX B LABORATORY TESTING Soil samples obtained from the explorations were transported to GeoEngineers’ laboratory and evaluated to confirm or modify field classifications, as well as to evaluate engineering properties of the soil samples. Representative samples were selected for laboratory testing to determine grain size distribution, moisture content, and percent fines (material passing the U.S. No. 200 sieve). The tests were performed in general accordance with test methods of ASTM International (ASTM) or other applicable procedures. Soil Classifications All soil samples obtained from the explorations were visually classified in the field and/or in our laboratory using a system based on the Unified Soil Classification System (USCS) and ASTM classification methods ASTM test method D 2488 was used to visually classify the soil samples, while ASTM D 2487 was used to classify the soils based on laboratory test results. These classification procedures are incorporated in the boring logs shown in Figure A-2 through A-11 in Appendix A. Moisture Content Determinations Moisture content tests were completed in general accordance with ASTM D 2216 for representative samples obtained from the explorations. The results of these tests are presented on the exploration logs in Appendix A at the respective sample depths. Percent Passing U.S. No. 200 Sieve (#F) Selected samples were “washed” through the No. 200 mesh sieve to estimate the relative percentages of coarse and fine-grained particles in the soil. The percent passing value represents the percentage by weight of the sample finer than the U.S. No. 200 sieve. These tests were conducted to verify field descriptions and to estimate the fines content for analysis purposes. The tests were conducted in accordance with ASTM D 1140, and the results of these tests are presented on the exploration logs in Appendix A at the respective sample depths. Sieve Analyses Sieve analyses were performed on selected samples in general accordance with ASTM D 422. The wet sieve analysis method was used to determine the percentage of soil greater than the U.S. No. 200 mesh sieve. The results of the sieve analyses were plotted and were classified in general accordance with the Unified Soil Classification System (USCS) and are presented in Figures B-1 and B-2. It should be noted that the sieve analyses were performed on soils obtained from samplers that have an opening size of 1½ inches, so larger sized particles cannot be obtained by the samplers. Therefore, the sieve results do not account for soil particles that are larger than 1½ inches. Soils with larger sized materials are described in this report qualitatively based on visual observations and experience on projects where excavations were made into similar formations. Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 0 10 20 30 40 50 60 70 80 90 100 0.0010.010.11101001000 PE R C E N T P A S S I N G B Y W E I G H T GRAIN SIZE IN MILLIMETERS U.S. STANDARD SIEVE SIZE 2” SAND SILT OR CLAYCOBBLESGRAVEL COARSE MEDIUM FINECOARSEFINE Boring Number Depth (feet)Soil Description GEI-1 GEI-1 GEI-4 GEI-6 2.5 5 2.5 7.5 Silty fine to medium sand with gravel (SM) Silty fine to medium sand (SM) Silty fine to medium sand with gravel (SM) Silty fine sand with gravel (SM) Symbol Moisture (%) 18 18 12 11 3/8”3”1.5”#4 #10 #20 #40 #60 #1003/4” Fi g u r e B -1 Si e v e A n a l y s i s R e s u l t s Re n t o n R e g i o n a l F i r e A u t h o r i t y , St a t i o n 1 6 R e p l a c e m e n t , Re n t o n , W a s h i n g t o n 20616-001-00 Date Exported: 07/19/2022 Note:This report may not be reproduced,except in full,without written approval of GeoEngineers,Inc.Test results are applicable only to the specific sample on which they were performed,and should not be interpreted as representative of any other samples obtainedat othertimes,depths or locations,or generated by separate operations orprocesses. Thegrain size analysis resultswereobtained in general accordance with ASTM C136.GeoEngineers 17425 NE Union Hill Road Ste 250,Redmond,WA 98052 #2001”#140 Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 0 10 20 30 40 50 60 70 80 90 100 0.0010.010.11101001000 PE R C E N T P A S S I N G B Y W E I G H T GRAIN SIZE IN MILLIMETERS U.S. STANDARD SIEVE SIZE 2” SAND SILT OR CLAYCOBBLESGRAVEL COARSE MEDIUM FINECOARSEFINE Boring Number Depth (feet)Soil Description GEI-9 GEI-10 15 2.5 Silty fine to medium sand with gravel (SM) Silty fine to medium sand with gravel (SM) Symbol Moisture (%) 15 17 3/8”3”1.5”#4 #10 #20 #40 #60 #1003/4” Fi g u r e B -2 Si e v e A n a l y s i s R e s u l t s Re n t o n R e g i o n a l F i r e A u t h o r i t y , St a t i o n 1 6 R e p l a c e m e n t , Re n t o n , W a s h i n g t o n 20616-001-00 Date Exported: 07/19/2022 Note:This report may not be reproduced,except in full,without written approval of GeoEngineers,Inc.Test results are applicable only to the specific sample on which they were performed,and should not be interpreted as representative of any other samples obtainedat othertimes,depths or locations,or generated by separate operations orprocesses. Thegrain size analysis resultswereobtained in general accordance with ASTM C136.GeoEngineers 17425 NE Union Hill Road Ste 250,Redmond,WA 98052 #2001”#140 Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 APPENDIX C Report Limitations and Guidelines for Use Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 August 5, 2022 | Page C-1 File No. 26016-001-00 APPENDIX C REPORT LIMITATIONS AND GUIDELINES FOR USE1 This appendix provides information to help you manage your risks with respect to the use of this report. Geotechnical Services Are Performed for Specific Purposes, Persons and Projects This report has been prepared for the exclusive use of Renton Regional Fire Authority (RRFA) and their authorized agents and/or regulatory agencies for the proposed Station 16 replacement project at 15815 SE 128th Street in Renton, Washington. This report is not intended for use by others, and the information contained herein is not applicable to other sites. GeoEngineers structures our services to meet the specific needs of our clients. For example, a geotechnical or geologic study conducted for a civil engineer or architect may not fulfill the needs of a construction contractor or even another civil engineer or architect that are involved in the same project. Because each geotechnical or geologic study is unique, each geotechnical engineering or geologic report is unique, prepared solely for the specific client and project site. Our report is prepared for the exclusive use of our Client. No other party may rely on the product of our services unless we agree in advance to such reliance in writing. This is to provide our firm with reasonable protection against open-ended liability claims by third parties with whom there would otherwise be no contractual limits to their actions. Within the limitations of scope, schedule and budget, our services have been executed in accordance with our Agreement with the Client and generally accepted geotechnical practices in this area at the time this report was prepared. This report should not be applied for any purpose or project except the one originally contemplated. A Geotechnical Engineering or Geologic Report Is Based on a Unique Set of Project-specific Factors This report has been prepared for the Station 16 replacement project located at 15815 SE 128th Street in Renton, Washington. GeoEngineers considered a number of unique, project-specific factors when establishing the scope of services for this project and report. Unless GeoEngineers specifically indicates otherwise, do not rely on this report if it was: ■ Not prepared for you, ■ Not prepared for your project, ■ Not prepared for the specific site explored, or ■ Completed before important project changes were made. For example, changes that can affect the applicability of this report include those that affect: 1 Developed based on material provided by GBA, GeoProfessional Business Association; www.geoprofessional.org. Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 August 5, 2022 | Page C-2 File No. 26016-001-00 ■ The function of the proposed structure, ■ Elevation, configuration, location, orientation or weight of the proposed structure, ■ Composition of the design team; or ■ Project ownership. If important changes are made after the date of this report, GeoEngineers should be given the opportunity to review our interpretations and recommendations and provide written modifications or confirmation, as appropriate. Subsurface Conditions Can Change This geotechnical or geologic report is based on conditions that existed at the time the study was performed. The findings and conclusions of this report may be affected by the passage of time, by manmade events such as construction on or adjacent to the site, or by natural events such as floods, earthquakes, slope instability or groundwater fluctuations. Always contact GeoEngineers before applying a report to determine if it remains applicable. Most Geotechnical and Geologic Findings Are Professional Opinions Our interpretations of subsurface conditions are based on field observations from widely spaced sampling locations at the site. Site exploration identifies subsurface conditions only at those points where subsurface tests are conducted or samples are taken. GeoEngineers reviewed field and laboratory data and then applied our professional judgment to render an opinion about subsurface conditions throughout the site. Actual subsurface conditions may differ, sometimes significantly, from those indicated in this report. Our report, conclusions and interpretations should not be construed as a warranty of the subsurface conditions. Geotechnical Engineering Report Recommendations Are Not Final Do not over-rely on the preliminary construction recommendations included in this report. These recommendations are not final, because they were developed principally from GeoEngineers’ professional judgment and opinion. GeoEngineers’ recommendations can be finalized only by observing actual subsurface conditions revealed during construction. GeoEngineers cannot assume responsibility or liability for this report's recommendations if we do not perform construction observation. Sufficient monitoring, testing and consultation by GeoEngineers should be provided during construction to confirm that the conditions encountered are consistent with those indicated by the explorations, to provide recommendations for design changes should the conditions revealed during the work differ from those anticipated, and to evaluate whether or not earthwork activities are completed in accordance with our recommendations. Retaining GeoEngineers for construction observation for this project is the most effective method of managing the risks associated with unanticipated conditions. A Geotechnical Engineering or Geologic Report Could Be Subject to Misinterpretation Misinterpretation of this report by other design team members can result in costly problems. You could lower that risk by having GeoEngineers confer with appropriate members of the design team after submitting the report. Also retain GeoEngineers to review pertinent elements of the design team's plans and specifications. Contractors can also misinterpret a geotechnical engineering or geologic report. Reduce that risk by having GeoEngineers participate in pre-bid and preconstruction conferences, and by providing construction observation. Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 August 5, 2022 | Page C-3 File No. 26016-001-00 Do Not Redraw the Exploration Logs Geotechnical engineers and geologists prepare final boring and testing logs based upon their interpretation of field logs and laboratory data. To prevent errors or omissions, the logs included in a geotechnical engineering or geologic report should never be redrawn for inclusion in architectural or other design drawings. Only photographic or electronic reproduction is acceptable but recognize that separating logs from the report can elevate risk. Give Contractors a Complete Report and Guidance Some owners and design professionals believe they can make contractors liable for unanticipated subsurface conditions by limiting what they provide for bid preparation. To help prevent costly problems, give contractors the complete geotechnical engineering or geologic report, but preface it with a clearly written letter of transmittal. In that letter, advise contractors that the report was not prepared for purposes of bid development and that the report's accuracy is limited; encourage them to confer with GeoEngineers and/or to conduct additional study to obtain the specific types of information they need or prefer. A pre-bid conference can also be valuable. Be sure contractors have sufficient time to perform additional study. Only then might an owner be in a position to give contractors the best information available, while requiring them to at least share the financial responsibilities stemming from unanticipated conditions. Further, a contingency for unanticipated conditions should be included in your project budget and schedule. Contractors Are Responsible for Site Safety on Their Own Construction Projects Our geotechnical recommendations are not intended to direct the contractor’s procedures, methods, schedule or management of the work site. The contractor is solely responsible for job site safety and for managing construction operations to minimize risks to on-site personnel and to adjacent properties. Read These Provisions Closely Some clients, design professionals and contractors may not recognize that the geoscience practices (geotechnical engineering or geology) are far less exact than other engineering and natural science disciplines. This lack of understanding can create unrealistic expectations that could lead to disappointments, claims and disputes. GeoEngineers includes these explanatory “limitations” provisions in our reports to help reduce such risks. Please confer with GeoEngineers if you are unclear how these “Report Limitations and Guidelines for Use” apply to your project or site. Geotechnical, Geologic and Environmental Reports Should Not Be Interchanged The equipment, techniques and personnel used to perform an environmental study differ significantly from those used to perform a geotechnical or geologic study and vice versa. For that reason, a geotechnical engineering or geologic report does not usually relate any environmental findings, conclusions or recommendations, e.g., about the likelihood of encountering underground storage tanks or regulated contaminants. Similarly, environmental reports are not used to address geotechnical or geologic concerns regarding a specific project. Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 August 5, 2022 | Page C-4 File No. 26016-001-00 Biological Pollutants GeoEngineers’ Scope of Work specifically excludes the investigation, detection, prevention or assessment of the presence of Biological Pollutants. Accordingly, this report does not include any interpretations, recommendations, findings, or conclusions regarding the detecting, assessing, preventing or abating of Biological Pollutants and no conclusions or inferences should be drawn regarding Biological Pollutants, as they may relate to this project. The term “Biological Pollutants” includes, but is not limited to, molds, fungi, spores, bacteria, and viruses, and/or any of their byproducts. If Client desires these specialized services, they should be obtained from a consultant who offers services in this specialized field. Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3 Docusign Envelope ID: 9C8AD163-664C-4B8F-8817-4315F1866DB3