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RS_Drainage Report_050426_APPROVED
TECHNICAL INFORMATION REPORT Schuder Residence 1632 Aberdeen Ave NE Renton, WA 98056 CG Project No. 25401.20 250 4th Ave S Ste 200 Edmonds, WA 98020 Phone: (425) 778-8500 Fax: (425) 778-5536 4/17/2026 DEVELOPMENT ENGINEERING HBray 07/06/2026 Surface Water Enginering jfarah 07/06/2026 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 | f. 425.778.5536 www.cgengineering.com Table of Contents TIR Section I – Project Overview TIR Section II – Conditions and Requirements Summary TIR Section III – Off-Site Analysis TIR Section IV – Flow Control, Low Impact Development (LID) and Water Quality Facility Analysis and Design TIR Section V – Conveyance System Analysis and Design TIR Section VI – Special Reports and Studies TIR Section VII – Other Permits TIR Section VIII – CSWPPP Analysis and Design TIR Section IX – Bond Quantities, Facility Summaries, and Declaration of Covenant TIR Section X – Operation and Maintenance Manual Schuder Residence - CG #25401.20 April 17, 2026 Technical Information Report Section I, Page 1 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 | f. 425.778.5536 www.cgengineering.com TIR Section I – Project Overview TIR Section I Summary Overview Predeveloped Condition Developed Condition List of Figures/Attachments: - TIR Worksheet - Site Location - Aerial Photograph Map - Site Drainage, Drainage Basins, Sub-basins, and Site Characteristics - Soils Overview This Drainage Report is for the Schuder Residence development project. The project is an addition being added to the existing house and two new ADU buildings on a 15,147 sf (0.348 ac) lot. The property is rectangular shaped which currently contains a single-family residence with associated driveway, and walkway areas. Site pervious areas generally consist of lawn and some trees. The proposed development consists of clearing and grading the site and the construction of the new addition to the existing single-family residence and two new ADU’s with a new associated driveway totaling 6,643 sf (0.153 ac) of new/replaced impervious surfaces on-site. Stormwater from the roof will downspout to a catch basin to the south of each building and then directed to a proposed on-site infiltration trench as per figure C.2.11.A of Appendix C of the City of Renton Surface Water Design Manual. Address: 1632 Aberdeen Ave NE Renton, WA 98056 Tax Parcel Number: 334390-1643 Zoning: R Drainage Basin: East Lake Washington - Renton Watershed: Cedar-Sammamish Predeveloped Condition The existing site contains a developed parcel totaling 0.348 acres. The site was formerly developed with a single-family residence and associated driveway located in the west half of the lot with the rest of the parcel being lawn. The current conditions include an associated driveway, single family residence with garage, shed, and walkway areas. The remainder of the site is landscaped with grass and a few trees. The site does not contain any wetlands, ponds, or streams. Site topography is flat with the site sloping inward at between 1%-3%. The property is bordered by a single-family lot to the north, east, and south, and Aberdeen Ave NE to the west. Street to the south and east (see Figures I-1 and I-2 for vicinity map and aerial image). See civil sheet 1 for a plan view of the site in its existing condition and see civil sheet 3 for proposed TESC measures. According to the geotechnical report by Geotech Consultants, Inc., the test pit revealed approximately 1.5 feet of loose silty sand fill soils with gravel, organics, and occasional plastic, metal, and glass debris overlying the remnant topsoil layer. Loose, native sand with silt and trace organics was encountered Schuder Residence - CG #25401.20 April 17, 2026 Technical Information Report Section I, Page 2 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 | f. 425.778.5536 www.cgengineering.com below the remnant topsoil became medium-dense to dense below 4 feet with a slightly increased silt content. Below 5.5 feet, occasional slightly silty lenses were observed within the sand. Infiltration is feasible due to the pilot infiltration test finding a measured infiltration rate of 27.3 in/hr. This gives a design infiltration rate of 7.6 in/hr. The project’s clearing limits were considered as this project’s land-disturbing activity area. The total land-disturbing activity area for the project is approximately 12,630 sf (0.290 ac). Developed Condition The site’s proposed development consists of removing the existing driveway, walkway, covered deck, and shed. Other alterations will be the demolition of the east facing side of the existing house so as to make room for the attached addition with some minor alterations to west side of the house’s main entry as well. The new/replaced impervious surface on-site is approximately 6,643 sf with a total of 3,761 sf of new roof area. In addition, about 85 sf of new/replaced impervious is proposed for the road saw cut replacement. The proposed addition to the existing single-family residence will be added to the east side of the existing home. See the impervious surfaces table below. The proposed impervious areas are as follows: Proposed Total Impervious: Addition Attached Garage Roof Area: 845 sf (0.019 ac) DADU Roof Area: 2,916 sf (0.067 ac) Walkways Area: 498 sf (0.011 ac) Driveway and Parking (On Site): 2,384 sf (0.055 ac) Road (Off Site): 85 sf (0.002 ac) Total Proposed Hard Surface: 6,728 sf (0.154 ac) Total Proposed Hard Surface (On-Site): 6,643 sf (0.153 ac) The project will undergo Direct Drainage Review because the project consists of more than 2,000 sf of new plus replaced impervious surface and it does not meet the requirements for Large Project Drainage Review. Thus, the project must comply with Core Requirements #1-9 and Special Requirements #1-6. Schuder Residence - CG #25401.20 April 17, 2026 Technical Information Report Section I, Page 3 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 | f. 425.778.5536 www.cgengineering.com Attachment I-1. Technical Information Report (TIR) Worksheet. See attached pages. Schuder Residence - CG #25401.20 April 17, 2026 Technical Information Report Section I, Page 4 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 | f. 425.778.5536 www.cgengineering.com Figure I-1: Vicinity map (from City of Renton Map) Figure I-2: Aerial image (from City of Renton Map) PROJECT SITE PROJECT SITE Schuder Residence - CG #25401.20 April 17, 2026 Technical Information Report Section I, Page 5 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 | f. 425.778.5536 www.cgengineering.com Figure I-3: Approximate flow route from project site (from City of Renton Map) Schuder Residence - CG #25401.20 April 17, 2026 Technical Information Report Section I, Page 6 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 | f. 425.778.5536 www.cgengineering.com Attachment I-2. Soils. Predominant underlying soils were determined using the USDA Natural Resources Conservation Service Web Soil Survey tool. The site contains Indianola loamy sand at 5 to 15 percent slopes. See attached pages. United States Department of Agriculture A product of the National Cooperative Soil Survey, a joint effort of the United States Department of Agriculture and other Federal agencies, State agencies including the Agricultural Experiment Stations, and local participants Custom Soil Resource Report for King County Area, Washington Schuder Residence Natural Resources Conservation Service October 10, 2025 9 Custom Soil Resource Report Soil Map 52 6 1 8 2 0 52 6 1 8 3 0 52 6 1 8 4 0 52 6 1 8 5 0 52 6 1 8 6 0 52 6 1 8 7 0 52 6 1 8 8 0 52 6 1 8 2 0 52 6 1 8 3 0 52 6 1 8 4 0 52 6 1 8 5 0 52 6 1 8 6 0 52 6 1 8 7 0 52 6 1 8 8 0 560920 560930 560940 560950 560960 560970 560980 560990 561000 561010 560920 560930 560940 560950 560960 560970 560980 560990 561000 561010 47° 30' 27'' N 12 2 ° 1 1 ' 2 7 ' ' W 47° 30' 27'' N 12 2 ° 1 1 ' 2 2 ' ' W 47° 30' 24'' N 12 2 ° 1 1 ' 2 7 ' ' W 47° 30' 24'' N 12 2 ° 1 1 ' 2 2 ' ' W N Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 10N WGS84 0 20 40 80 120 Feet 0 5 10 20 30 Meters Map Scale: 1:465 if printed on A landscape (11" x 8.5") sheet. Soil Map may not be valid at this scale. MAP LEGEND MAP INFORMATION Area of Interest (AOI) Area of Interest (AOI) Soils Soil Map Unit Polygons Soil Map Unit Lines Soil Map Unit Points Special Point Features Blowout Borrow Pit Clay Spot Closed Depression Gravel Pit Gravelly Spot Landfill Lava Flow Marsh or swamp Mine or Quarry Miscellaneous Water Perennial Water Rock Outcrop Saline Spot Sandy Spot Severely Eroded Spot Sinkhole Slide or Slip Sodic Spot Spoil Area Stony Spot Very Stony Spot Wet Spot Other Special Line Features Water Features Streams and Canals Transportation Rails Interstate Highways US Routes Major Roads Local Roads Background Aerial Photography The soil surveys that comprise your AOI were mapped at 1:24,000. Warning: Soil Map may not be valid at this scale. Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale. Please rely on the bar scale on each map sheet for map measurements. Source of Map: Natural Resources Conservation Service Web Soil Survey URL: Coordinate System: Web Mercator (EPSG:3857) Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required. This product is generated from the USDA-NRCS certified data as of the version date(s) listed below. Soil Survey Area: King County Area, Washington Survey Area Data: Version 20, Aug 27, 2024 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Mar 1, 2023—Sep 1, 2023 The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting of map unit boundaries may be evident. Custom Soil Resource Report 10 Map Unit Legend Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI InC Indianola loamy sand, 5 to 15 percent slopes 0.5 100.0% Totals for Area of Interest 0.5 100.0% Map Unit Descriptions The map units delineated on the detailed soil maps in a soil survey represent the soils or miscellaneous areas in the survey area. The map unit descriptions, along with the maps, can be used to determine the composition and properties of a unit. A map unit delineation on a soil map represents an area dominated by one or more major kinds of soil or miscellaneous areas. A map unit is identified and named according to the taxonomic classification of the dominant soils. Within a taxonomic class there are precisely defined limits for the properties of the soils. On the landscape, however, the soils are natural phenomena, and they have the characteristic variability of all natural phenomena. Thus, the range of some observed properties may extend beyond the limits defined for a taxonomic class. Areas of soils of a single taxonomic class rarely, if ever, can be mapped without including areas of other taxonomic classes. Consequently, every map unit is made up of the soils or miscellaneous areas for which it is named and some minor components that belong to taxonomic classes other than those of the major soils. Most minor soils have properties similar to those of the dominant soil or soils in the map unit, and thus they do not affect use and management. These are called noncontrasting, or similar, components. They may or may not be mentioned in a particular map unit description. Other minor components, however, have properties and behavioral characteristics divergent enough to affect use or to require different management. These are called contrasting, or dissimilar, components. They generally are in small areas and could not be mapped separately because of the scale used. Some small areas of strongly contrasting soils or miscellaneous areas are identified by a special symbol on the maps. If included in the database for a given area, the contrasting minor components are identified in the map unit descriptions along with some characteristics of each. A few areas of minor components may not have been observed, and consequently they are not mentioned in the descriptions, especially where the pattern was so complex that it was impractical to make enough observations to identify all the soils and miscellaneous areas on the landscape. The presence of minor components in a map unit in no way diminishes the usefulness or accuracy of the data. The objective of mapping is not to delineate pure taxonomic classes but rather to separate the landscape into landforms or landform segments that have similar use and management requirements. The delineation of such segments on the map provides sufficient information for the development of resource plans. If intensive use of small areas is planned, however, onsite investigation is needed to define and locate the soils and miscellaneous areas. Custom Soil Resource Report 11 Schuder Residence - CG #25401.20 April 17, 2026 Technical Information Report Section II, Page 1 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 | f. 425.778.5536 www.cgengineering.com TIR Section II – Conditions and Requirements Summary TIR Section II Summary Narrative Core Requirements Special Requirements The project will comply with the 2022 City of Renton SWDM. Per the drainage review flow chart (Figure II-1) and Chapter 1.1.2 from the SWDM, the project is being submitted for Directed Drainage Review because it is a single-family residence project that is not subject to Large Project Drainage Review. The project must address all 9 Core Requirements and all 5 Special Requirements. Therefore, the following conditions are required as specified by City of Renton SWDM. Core Requirements Core Requirement #1: Discharge at the Natural Location: The overall topography of the subject property is relatively flat, descending west at an average slope of 1%. This drainage pattern will be maintained by taking stormwater from the roof and conveying the runoff to a proposed infiltration trench onsite. Any stormwater not infiltrated on site will flow off site and into the public storm system along Aberdeen Ave NE. Core Requirement #2: Offsite Analysis: An offsite analysis is provided in Section III. Core Requirement #3: Flow Control: Flow control is required for projects in which the total effective impervious surfaces are 5,000 sf of new plus replaced target impervious surface (6,643 sf) or more in a threshold discharge area and convert ¾ acres or more of vegetation to lawn or landscape. The project is exempt from flow control as 6,643 sf is being infiltrated and less than ¾ acres of vegetation is being converted. Therefore, this project is exempt from flow control. See Section IV. Core Requirement #4: Conveyance System: New pipe systems are proposed and were designed to meet the 25-year peak flow capacity. See Section V. Core Requirement #5: Erosion & Sediment Control: A Construction Stormwater Pollution Prevention Plan (CSWPPP) and narrative has been prepared. See Section VIII. Core Requirement #6: Maintenance & Operations: Maintenance requirements are addressed in Section X for the proposed Flow Control BMP. Core Requirement #7: Financial Guarantees & Liabilities: Applicable because private drainage facilities will be connected to public system. See attached Bond Quantities Sheet for further details. Core Requirement #8: Water Quality: Not applicable per Exemption #1 (Surface Area Exemption). Less than 5,000 square feet of new plus replaced PGIS and less than ¾ acres of new PGPS are proposed. Core Requirement #9: On-Site BMPs: The project is exempt from flow control as all proposed and replaced impervious surfaces are served by an infiltration facility designed in accordance with the flow control facility requirement (Section 1.2.3.1), the facility implementation requirements (Section 1.2.3.2), Schuder Residence - CG #25401.20 April 17, 2026 Technical Information Report Section II, Page 2 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 | f. 425.778.5536 www.cgengineering.com and the design criteria for infiltration facilities (Section 5.2) is exempt from the on-site BMP requirements. See Section IV. Special Requirements Special Requirement #1: Other Adopted Requirements: Not applicable. Special Requirement #2: Flood Hazard Area Delineation: Not applicable. Special Requirement #3: Flood Protection Facilities: Not applicable. Special Requirement #4: Source Control: Not applicable. Special Requirement #5: Oil Control: Not applicable. Special Requirement #6: Aquifer Protection Area: Aquifer Protection is required for projects in a Zone 1 modified or Zone 2 of the APA. The project will meet Special Requirement #6 by constructing a separate infiltration trench for the pollution generating impervious surfaces. This separate infiltration trench will have a maximum infiltration rate of 2.4 in/hr and was designed with an infiltration rate of 1.2 in/hr. Schuder Residence - CG #25401.20 April 17, 2026 Technical Information Report Section II, Page 3 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 | f. 425.778.5536 www.cgengineering.com Figure II-1: Drainage review flow chart from 2022 City of Renton Surface Water Design Manual Schuder Residence - CG #25401.20 April 17, 2026 Technical Information Report Section III, Page 1 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 | f. 425.778.5536 www.cgengineering.com TIR Section III – Off-Site Analysis TIR Section III Summary Task 1: Study Area Definition and Maps Task 2: Resource Review Task 3: Field Inspection Task 4: Drainage System Description and Problem Descriptions Task 5: Mitigation of Existing or Potential Problems Task 1: Study Area Definition and Maps The study area is defined as the project site and the area one mile downstream (minimum flow path distance) from the proposed discharge location, for the purposes of Task 2, and is defined as the project site and a minimum of one-quarter mile downstream from the proposed discharge location for the purposes of Tasks 3, 4, and 5. The site location is in the City of Renton. The current site conditions include a driveway, with an existing single-family residence, and walkway. Site pervious areas generally consist of vegetation with grasses, bushes, shrubs, along with trees. Site topography slopes downward from east to west at an average slope of about 1%. The site is located inside Renton and is in the May Creek drainage basin and the Cedar River/Lake Washington watershed. Approximate flow route from project site can be found in Figure III-1 in Section III. Task 2: Resource Review Drainage and water quality problems and complaints were investigated using City of Renton iMap and DOE’s Water Quality Atlas. There do not appear to be any relevant complaints in recent years that pertain to the route that runoff would follow from the project site. City of Renton iMap states East Lake Washington is the drainage basin with Cedar-Sammamish watershed. Figure III-1 shows a snip from the city of Renton iMap with the approximate flow route from the site. See Figures III-2 through III-5 for pictures of the existing site and downstream conditions. The sensitive areas and complaints will be discussed in Task 5. Task 3: Field Inspection A site visit was made on the afternoon of October 14, 2025 (see Figures III-2 through III-5 for pictures). It was a clear day at the time of the site visit. From the site visit, it was confirmed that the site is flat with very little slope. Stormwater from the new and replaced hard surface consisting of the proposed roof, walkways, and driveway will be conveyed to proposed catch basins. From there, the stormwater is conveyed to a proposed infiltration trench on site. Any stormwater not infiltrated will flow off site to the west into the public storm system along Aberdeen Ave NE. Schuder Residence - CG #25401.20 April 17, 2026 Technical Information Report Section III, Page 2 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 | f. 425.778.5536 www.cgengineering.com Figure III-1: Approximate flow route from project site (from City of Renton Map) Schuder Residence - CG #25401.20 April 17, 2026 Technical Information Report Section III, Page 3 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 | f. 425.778.5536 www.cgengineering.com Task 4: Drainage System Description and Problem Descriptions The conveyance system will consist of at least a 4” PVC pipes for the house’s footing drains. A 6” PVC pipe for the house’s roof drains is typical and 8” PVC pipes between proposed catch basins. Roof runoff will be piped from the roof drains to proposed catch basins to the south of the proposed addition and DADUs then convey runoff to the onsite Infiltration trench. Task 5: Mitigation of Existing or Potential Problems Impacts from runoff are expected to not cause any problems downstream. All stormwater is mitigated on site with an onsite infiltration trench. The development associated with this project is not expected to negatively impact the current drainage patterns of the surrounding area. Schuder Residence - CG #25401.20 April 17, 2026 Technical Information Report Section III, Page 4 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 | f. 425.778.5536 www.cgengineering.com Figure III-2: View facing west from onsite with approximate drainage direction of the site. Aberdeen Ave NE PROJECT SITE Schuder Residence - CG #25401.20 April 17, 2026 Technical Information Report Section III, Page 5 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 | f. 425.778.5536 www.cgengineering.com Figure III-3: View facing north from ROW of site along Aberdeen Ave NE. Aberdeen Ave NE Schuder Residence - CG #25401.20 April 17, 2026 Technical Information Report Section III, Page 6 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 | f. 425.778.5536 www.cgengineering.com Figure III-4: View facing North at the intersection of Aberdeen Ave NE and NE 20th St. Aberdeen Ave NE Schuder Residence - CG #25401.20 April 17, 2026 Technical Information Report Section III, Page 7 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 | f. 425.778.5536 www.cgengineering.com Figure III-5: View facing north about ¼ mile from site along Aberdeen Ave NE. Aberdeen Ave NE ~ ¼ mile form Site Schuder Residence - CG #25401.20 April 17, 2026 Technical Information Report Section IV, Page 1 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 | f. 425.778.5536 www.cgengineering.com TIR Section IV – Flow Control, Low Impact Development (LID) and Water Quality Facility Analysis and Design TIR Section IV Summary: Narrative PART A: Existing Site Hydrology PART B: Developed Site Hydrology PART C: Performance Standards PART D: Flow Control System PART E: Water Quality System List of Figures/Attachments: - WWHM Report 0.15. - WWHM Report Infiltration Trench for Roof Area - WWHM Report Infiltration Trench for Driveway Area We are required to address Flow control per Core Requirement #3 as the project proposes more than 5,000 sf of new and/or replaced hard surface area being added to the site. PART A: EXISTING SITE HYDROLOGY The current site conditions include an associated driveway, single family residence, Shed, and walkway. The remainder of the site is lawn and some trees. The total lot area is approximately 15,147 sf (0.348 ac) and the proposed area of development on-site (the proposed clearing limits area) is approximately 12,630 sf (0.290 ac). Site topography slopes from east to west at an average slope of about 1.0% Therefore, the site’s natural discharge location is to the west. PART B: DEVELOPED SITE HYDROLOGY The proposed development consists of clearing and grading the site and the construction of a new addition add to the east side of the existing home. Two new DADU’s will be added to the west of the site along with an associated driveway and walkways. A total of 3,761 sf of roof area is proposed, 498 sf of walkway, and 2,384 sf of driveway giving a total proposed new/replaced impervious area of 6,643 sf (0.153 ac). The proposed addition will be added to the east of the existing single-family residence. Design and infeasibility criteria from Appendix C of the SWDM were used to determine feasibility of Flow Control BMPs for this project’s site improvements. Since the project is on a lot that is between ½ acre and 5 acres in area, the project must evaluate Large Lot BMP requirements of Section C.1.3.2 of the SWDM. Full Dispersion was determined to be infeasible for this site because there is not enough space due to site constraints. Infiltration BMPs were determined to be feasible per the geotechnical engineer’s evaluation. See Part D for more. Schuder Residence - CG #25401.20 April 17, 2026 Technical Information Report Section IV, Page 2 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 | f. 425.778.5536 www.cgengineering.com The proposed impervious areas are as follows: Proposed Total Impervious: Addition Roof Area: 845 sf (0.019 ac) ADU/Garage Structure Roof Area: 2,916 sf (0.067 ac) Walkways / Sidewalks / Steppingstone Area: 498 sf (0.011 ac) Driveway and Parking (On Site): 2,384 sf (0.055 ac) Total Proposed Hard Surface: 6,643 sf (0.153 ac) PART C: PERFORMANCE STANDARDS We are required to address Flow control per Core Requirement #3 because the site proposes more than 5,000 sf of new plus replaced impervious surface. Water quality is not required for this project per the Basic Exemptions. Flow Frequency Flow(cfs) Predeveloped Mitigated 2 Year = 0.0002 0.0587 5 Year = 0.0004 0.0757 10 Year = 0.0005 0.0876 25 Year = 0.0006 0.1035 50 Year = 0.0008 0.1159 100 Year = 0.0009 0.1289 0.1289 - 0.0009 = 0.128 Conveyance System Capacity Standard: Per Core Requirement #4, new pipe systems shall be designed with sufficient capacity to convey and contain (at minimum) the 25-year peak flow. Conveyance capacity shall be demonstrated using the methods in Chapter 4 of the RSWDM. See Section V for Conveyance Analysis and Design. PART D: FLOW CONTROL SYSTEM The project proposes more than 5,000 sf of new and replaced impervious surfaces. And Flow control per Core requirement #3 is not required. As mentioned in Section II, flow control BMPs must be considered for the project. The project must meet the full drainage BMP Requirements of Section 1.1.2.4. 1. Full Dispersion is infeasible because there is insufficient space on site. There is not enough space to allow for a dispersion trench. 2. Full and/or Limited Infiltration Systems are feasible as per the geotechnical engineer’s evaluation found in section VI, an infiltration rate of 7.6 in/hr was found. 3. Bioretention was not evaluated as Infiltration is being used. 4. Permeable Pavement was not evaluated as Infiltration is being used. 5. Basic Dispersion was not evaluated as Infiltration is being used. 6. Downspout Dispersion Systems in accordance with BMP T5.10B was not evaluated as Infiltration is being used. 7. Perforated Pipe Connections was not evaluated as Infiltration is being used. The project proposes more than 5,000 sf of new and replaced target impervious surfaces. Stormwater runoff from the new roof area hard surfaces will be directed into a proposed 31’ x 5’ x 3’ gravel infiltration trenches for Full Infiltration. Stormwater runoff from the new paved area will be directed Schuder Residence - CG #25401.20 April 17, 2026 Technical Information Report Section IV, Page 3 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 | f. 425.778.5536 www.cgengineering.com into two proposed 32’ x 5’ x 3’ gravel infiltration trenches and one proposed 32’ x 4’ x 3’ gravel infiltration trenches for Full Infiltration. The infiltration trenches were designed per Full Infiltration requirements of Section 5.2.5 of the RSWDM. See Section IV and the civil plans for more details. Figure IV-1: Basin Map for Target Surfaces PART E: WATER QUALITY SYSTEM The project proposes less than 5,000 square feet of PGIS and, therefore, will not require water quality treatment (Exemption #1 Surface Area Exemption in Chapter 1, Section 1.2.8) Aquifer Protection Area Zone 2 and Liner Requirements Since the project is in an Aquifer Protection Area Zone 2, the project will need to meet Special Requirement #6 by constructing a separate infiltration trench for the pollution generating impervious surfaces. This separate infiltration trenches for the pollution generating surfaces will have a maximum infiltration rate of 2.4 in/hr and was designed with an infiltration rate of 1.2 in/hr. This will be accomplished by a Geomembrane liner that has a minimum thickness of 30 MILS placed directly below the trenches. Schuder Residence - CG #25401.20 April 17, 2026 Technical Information Report Section IV, Page 4 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 | f. 425.778.5536 www.cgengineering.com Attachment IV-1. WWHM Report 0.15. Flow control duration 0.15-cfs comparing matching forested site conditions to proposed conditions. Proposed impervious areas are to be fully infiltrated and therefore have been subtracted from this check per table 1.2.9.A On-Site BMP Sizing Credits in City of Renton SWDM. Schuder Residence - CG #25401.20 April 17, 2026 Technical Information Report Section IV, Page 5 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 | f. 425.778.5536 www.cgengineering.com WWHM2012 PROJECT REPORT ___________________________________________________________________ Project Name: Schuder 0.15 Check Site Name: Schuder Residence Site Address: 1632 Aberdeen Ave NE Renton, WA 98056 City : Renton Report Date: 2/19/2026 Gage : Seatac Data Start : 1948/10/01 Data End : 2009/09/30 Precip Scale: 1.00 Version Date: 2025/05/13 Version : 4.3.2 ___________________________________________________________________ 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 A B, Forest, Flat 0.289 Pervious Total 0.289 Impervious Land Use acre Impervious Total 0 Basin Total 0.289 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ MITIGATED LAND USE Name : Basin 1 Bypass: No GroundWater: No Schuder Residence - CG #25401.20 April 17, 2026 Technical Information Report Section IV, Page 6 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 | f. 425.778.5536 www.cgengineering.com Pervious Land Use acre A B, Lawn, Flat 0.137 Pervious Total 0.137 Impervious Land Use acre ROOF TOPS FLAT 0.086 DRIVEWAYS FLAT 0.055 SIDEWALKS FLAT 0.011 Impervious Total 0.152 Basin Total 0.289 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ ANALYSIS RESULTS Stream Protection Duration ___________________________________________________________________ Predeveloped Landuse Totals for POC #1 Total Pervious Area:0.289 Total Impervious Area:0 ___________________________________________________________________ Mitigated Landuse Totals for POC #1 Total Pervious Area:0.137 Total Impervious Area:0.152 ___________________________________________________________________ Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.000245 5 year 0.000371 10 year 0.000474 25 year 0.000628 50 year 0.000762 100 year 0.000914 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0.058743 5 year 0.075662 10 year 0.087573 25 year 0.103461 50 year 0.115927 100 year 0.128949 _____________________________________________________ Schuder Residence - CG #25401.20 April 17, 2026 Technical Information Report Section IV, Page 7 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 | f. 425.778.5536 www.cgengineering.com 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 = Failed ___________________________________________________________________ ___________________________________________________________________ CHANGES TO PERLND AND IMPLND PARAMETER VALUES. A Total of 0 changes have been made. PERLND NAME Parameter Name Original Value New Value No PERLND changes have been made.IMPLND NAME Parameter Name Original Value New Value IMPLND 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. 2005-2026; All Rights Reserved. Schuder Residence - CG #25401.20 April 17, 2026 Technical Information Report Section IV, Page 8 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 | f. 425.778.5536 www.cgengineering.com Attachment IV-2. WWHM Report Infiltration Trench. Per Core Requirement #3, the proposed infiltration trench for roof area was designed for 100% of the 50-year peak flow with an infiltration rate of 7.6 in/hr. Schuder Residence - CG #25401.20 April 17, 2026 Technical Information Report Section IV, Page 9 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 | f. 425.778.5536 www.cgengineering.com WWHM2012 PROJECT REPORT ___________________________________________________________________ Project Name: Schuder Infiltration of Roof Site Name: Schuder Residence Site Address: 1632 Aberdeen Ave NE Renton, WA 98056 City : Renton Report Date: 4/16/2026 Gage : Seatac Data Start : 1948/10/01 Data End : 2009/09/30 Precip Scale: 1.00 Version Date: 2025/05/13 Version : 4.3.2 ___________________________________________________________________ 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 A B, Forest, Flat 0.086 Pervious Total 0.086 Impervious Land Use acre Impervious Total 0 Basin Total 0.086 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ MITIGATED LAND USE Name : Basin 1 Bypass: No GroundWater: No Schuder Residence - CG #25401.20 April 17, 2026 Technical Information Report Section IV, Page 10 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 | f. 425.778.5536 www.cgengineering.com Pervious Land Use acre Pervious Total 0 Impervious Land Use acre ROOF TOPS FLAT 0.086 Impervious Total 0.086 Basin Total 0.086 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater Gravel Trench Bed 1 Gravel Trench Bed 1 ___________________________________________________________________ Name : Gravel Trench Bed 1 Bottom Length: 31.00 ft. Bottom Width: 5.00 ft. Trench bottom slope 1: 0 To 1 Trench Left side slope 0: 0 To 1 Trench right side slope 2: 0 To 1 Material thickness of first layer: 3 Pour Space of material for first layer: 0.3 Material thickness of second layer: 0 Pour Space of material for second layer: 0 Material thickness of third layer: 0 Pour Space of material for third layer: 0 Infiltration On Infiltration rate: 7.6 Infiltration safety factor: 1 Total Volume Infiltrated (ac-ft.): 13.173 Total Volume Through Riser (ac-ft.): 0 Total Volume Through Facility (ac-ft.): 13.173 Percent Infiltrated: 100 Total Precip Applied to Facility: 0 Total Evap From Facility: 0 Discharge Structure Riser Height: 2.95 ft. Riser Diameter: 12 in. Element Flows To: Outlet 1 Outlet 2 ___________________________________________________________________ Gravel Trench Bed Hydraulic Table Stage(feet) Area(ac.) Volume(ac-ft.) Discharge(cfs) Infilt(cfs) 0.0000 0.003 0.000 0.000 0.000 0.0333 0.003 0.000 0.000 0.027 0.0667 0.003 0.000 0.000 0.027 Schuder Residence - CG #25401.20 April 17, 2026 Technical Information Report Section IV, Page 11 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 | f. 425.778.5536 www.cgengineering.com 0.1000 0.003 0.000 0.000 0.027 0.1333 0.003 0.000 0.000 0.027 0.1667 0.003 0.000 0.000 0.027 0.2000 0.003 0.000 0.000 0.027 0.2333 0.003 0.000 0.000 0.027 0.2667 0.003 0.000 0.000 0.027 0.3000 0.003 0.000 0.000 0.027 0.3333 0.003 0.000 0.000 0.027 0.3667 0.003 0.000 0.000 0.027 0.4000 0.003 0.000 0.000 0.027 0.4333 0.003 0.000 0.000 0.027 0.4667 0.003 0.000 0.000 0.027 0.5000 0.003 0.000 0.000 0.027 0.5333 0.003 0.000 0.000 0.027 0.5667 0.003 0.000 0.000 0.027 0.6000 0.003 0.000 0.000 0.027 0.6333 0.003 0.000 0.000 0.027 0.6667 0.003 0.000 0.000 0.027 0.7000 0.003 0.000 0.000 0.027 0.7333 0.003 0.000 0.000 0.027 0.7667 0.003 0.000 0.000 0.027 0.8000 0.003 0.000 0.000 0.027 0.8333 0.003 0.000 0.000 0.027 0.8667 0.003 0.000 0.000 0.027 0.9000 0.003 0.001 0.000 0.027 0.9333 0.003 0.001 0.000 0.027 0.9667 0.003 0.001 0.000 0.027 1.0000 0.003 0.001 0.000 0.027 1.0333 0.003 0.001 0.000 0.027 1.0667 0.003 0.001 0.000 0.027 1.1000 0.003 0.001 0.000 0.027 1.1333 0.003 0.001 0.000 0.027 1.1667 0.003 0.001 0.000 0.027 1.2000 0.003 0.001 0.000 0.027 1.2333 0.003 0.001 0.000 0.027 1.2667 0.003 0.001 0.000 0.027 1.3000 0.003 0.001 0.000 0.027 1.3333 0.003 0.001 0.000 0.027 1.3667 0.003 0.001 0.000 0.027 1.4000 0.003 0.001 0.000 0.027 1.4333 0.003 0.001 0.000 0.027 1.4667 0.003 0.001 0.000 0.027 1.5000 0.003 0.001 0.000 0.027 1.5333 0.003 0.001 0.000 0.027 1.5667 0.003 0.001 0.000 0.027 1.6000 0.003 0.001 0.000 0.027 1.6333 0.003 0.001 0.000 0.027 1.6667 0.003 0.001 0.000 0.027 1.7000 0.003 0.001 0.000 0.027 1.7333 0.003 0.001 0.000 0.027 1.7667 0.003 0.001 0.000 0.027 1.8000 0.003 0.001 0.000 0.027 1.8333 0.003 0.002 0.000 0.027 1.8667 0.003 0.002 0.000 0.027 1.9000 0.003 0.002 0.000 0.027 1.9333 0.003 0.002 0.000 0.027 1.9667 0.003 0.002 0.000 0.027 Schuder Residence - CG #25401.20 April 17, 2026 Technical Information Report Section IV, Page 12 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 | f. 425.778.5536 www.cgengineering.com 2.0000 0.003 0.002 0.000 0.027 2.0333 0.003 0.002 0.000 0.027 2.0667 0.003 0.002 0.000 0.027 2.1000 0.003 0.002 0.000 0.027 2.1333 0.003 0.002 0.000 0.027 2.1667 0.003 0.002 0.000 0.027 2.2000 0.003 0.002 0.000 0.027 2.2333 0.003 0.002 0.000 0.027 2.2667 0.003 0.002 0.000 0.027 2.3000 0.003 0.002 0.000 0.027 2.3333 0.003 0.002 0.000 0.027 2.3667 0.003 0.002 0.000 0.027 2.4000 0.003 0.002 0.000 0.027 2.4333 0.003 0.002 0.000 0.027 2.4667 0.003 0.002 0.000 0.027 2.5000 0.003 0.002 0.000 0.027 2.5333 0.003 0.002 0.000 0.027 2.5667 0.003 0.002 0.000 0.027 2.6000 0.003 0.002 0.000 0.027 2.6333 0.003 0.002 0.000 0.027 2.6667 0.003 0.002 0.000 0.027 2.7000 0.003 0.002 0.000 0.027 2.7333 0.003 0.002 0.000 0.027 2.7667 0.003 0.003 0.000 0.027 2.8000 0.003 0.003 0.000 0.027 2.8333 0.003 0.003 0.000 0.027 2.8667 0.003 0.003 0.000 0.027 2.9000 0.003 0.003 0.000 0.027 2.9333 0.003 0.003 0.000 0.027 2.9667 0.003 0.003 0.022 0.027 3.0000 0.003 0.003 0.118 0.027 ___________________________________________________________________ ___________________________________________________________________ ANALYSIS RESULTS Stream Protection Duration ___________________________________________________________________ Predeveloped Landuse Totals for POC #1 Total Pervious Area:0.086 Total Impervious Area:0 ___________________________________________________________________ Mitigated Landuse Totals for POC #1 Total Pervious Area:0 Total Impervious Area:0.086 ___________________________________________________________________ Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.000073 5 year 0.00011 10 year 0.000141 25 year 0.000187 Schuder Residence - CG #25401.20 April 17, 2026 Technical Information Report Section IV, Page 13 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 | f. 425.778.5536 www.cgengineering.com 50 year 0.000227 100 year 0.000272 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0 5 year 0 10 year 0 25 year 0 50 year 0 100 year 0 ___________________________________________________________________ Stream Protection Duration POC #1 The Facility PASSED The Facility PASSED. Flow(cfs) Predev Mit Percentage Pass/Fail 0.0000 3099 0 0 Pass 0.0000 2776 0 0 Pass 0.0000 2458 0 0 Pass 0.0000 2177 0 0 Pass 0.0000 1924 0 0 Pass 0.0000 1691 0 0 Pass 0.0000 1475 0 0 Pass 0.0000 1394 0 0 Pass 0.0001 1241 0 0 Pass 0.0001 1080 0 0 Pass 0.0001 908 0 0 Pass 0.0001 730 0 0 Pass 0.0001 581 0 0 Pass 0.0001 467 0 0 Pass 0.0001 366 0 0 Pass 0.0001 264 0 0 Pass 0.0001 152 0 0 Pass 0.0001 37 0 0 Pass 0.0001 26 0 0 Pass 0.0001 26 0 0 Pass 0.0001 26 0 0 Pass 0.0001 26 0 0 Pass 0.0001 25 0 0 Pass 0.0001 25 0 0 Pass 0.0001 24 0 0 Pass 0.0001 23 0 0 Pass 0.0001 23 0 0 Pass 0.0001 23 0 0 Pass 0.0001 22 0 0 Pass 0.0001 22 0 0 Pass 0.0001 22 0 0 Pass 0.0001 21 0 0 Pass 0.0001 21 0 0 Pass 0.0001 21 0 0 Pass 0.0001 21 0 0 Pass 0.0001 19 0 0 Pass Schuder Residence - CG #25401.20 April 17, 2026 Technical Information Report Section IV, Page 14 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 | f. 425.778.5536 www.cgengineering.com 0.0001 19 0 0 Pass 0.0001 19 0 0 Pass 0.0001 18 0 0 Pass 0.0001 18 0 0 Pass 0.0001 16 0 0 Pass 0.0001 16 0 0 Pass 0.0001 16 0 0 Pass 0.0001 16 0 0 Pass 0.0001 16 0 0 Pass 0.0001 15 0 0 Pass 0.0001 15 0 0 Pass 0.0001 15 0 0 Pass 0.0001 14 0 0 Pass 0.0001 13 0 0 Pass 0.0001 13 0 0 Pass 0.0001 13 0 0 Pass 0.0001 13 0 0 Pass 0.0001 13 0 0 Pass 0.0001 13 0 0 Pass 0.0001 12 0 0 Pass 0.0001 12 0 0 Pass 0.0001 12 0 0 Pass 0.0001 11 0 0 Pass 0.0002 11 0 0 Pass 0.0002 11 0 0 Pass 0.0002 11 0 0 Pass 0.0002 10 0 0 Pass 0.0002 10 0 0 Pass 0.0002 10 0 0 Pass 0.0002 9 0 0 Pass 0.0002 9 0 0 Pass 0.0002 9 0 0 Pass 0.0002 9 0 0 Pass 0.0002 8 0 0 Pass 0.0002 8 0 0 Pass 0.0002 8 0 0 Pass 0.0002 8 0 0 Pass 0.0002 8 0 0 Pass 0.0002 8 0 0 Pass 0.0002 8 0 0 Pass 0.0002 8 0 0 Pass 0.0002 8 0 0 Pass 0.0002 8 0 0 Pass 0.0002 8 0 0 Pass 0.0002 8 0 0 Pass 0.0002 8 0 0 Pass 0.0002 8 0 0 Pass 0.0002 8 0 0 Pass 0.0002 8 0 0 Pass 0.0002 8 0 0 Pass 0.0002 8 0 0 Pass 0.0002 8 0 0 Pass 0.0002 8 0 0 Pass 0.0002 8 0 0 Pass 0.0002 8 0 0 Pass 0.0002 8 0 0 Pass 0.0002 8 0 0 Pass Schuder Residence - CG #25401.20 April 17, 2026 Technical Information Report Section IV, Page 15 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 | f. 425.778.5536 www.cgengineering.com 0.0002 8 0 0 Pass 0.0002 8 0 0 Pass 0.0002 8 0 0 Pass 0.0002 8 0 0 Pass 0.0002 8 0 0 Pass 0.0002 8 0 0 Pass 0.0002 8 0 0 Pass _____________________________________________________ ___________________________________________________________________ Water Quality BMP Flow and Volume for POC #1 On-line facility volume: 0.0081 acre-feet On-line facility target flow: 0.0108 cfs. Adjusted for 15 min: 0.0108 cfs. Off-line facility target flow: 0.0061 cfs. Adjusted for 15 min: 0.0061 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 Gravel Trench Bed 1 POC N 11.99 N 100.00 Total Volume Infiltrated 11.99 0.00 0.00 100.00 0.00 0% No Treat. Credit Compliance with LID Standard 8 Duration Analysis Result = Passed ___________________________________________________________________ ___________________________________________________________________ CHANGES TO PERLND AND IMPLND PARAMETER VALUES. A Total of 0 changes have been made. PERLND NAME Parameter Name Original Value New Value No PERLND changes have been made.IMPLND NAME Parameter Name Original Value New Value IMPLND 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. 2005-2026; All Rights Reserved. Schuder Residence - CG #25401.20 April 17, 2026 Technical Information Report Section IV, Page 16 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 | f. 425.778.5536 www.cgengineering.com Attachment IV-3. WWHM Report Infiltration Trench. Per Core Requirement #3, the proposed infiltration trench for driveway area was designed for 100% of the 50-year peak flow with an infiltration rate of 1.2 in/hr. Schuder Residence - CG #25401.20 April 17, 2026 Technical Information Report Section IV, Page 17 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 | f. 425.778.5536 www.cgengineering.com WWHM2012 PROJECT REPORT ___________________________________________________________________ Project Name: Schuder Infiltration of Pavement Site Name: Schuder Residence Site Address: 1632 Aberdeen Ave NE Renton, WA 98056 City : Renton Report Date: 4/16/2026 Gage : Seatac Data Start : 1948/10/01 Data End : 2009/09/30 Precip Scale: 1.00 Version Date: 2025/05/13 Version : 4.3.2 ___________________________________________________________________ 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 A B, Forest, Flat 0.144 Pervious Total 0.144 Impervious Land Use acre Impervious Total 0 Basin Total 0.144 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater ___________________________________________________________________ MITIGATED LAND USE Name : Basin 1 Bypass: No GroundWater: No Schuder Residence - CG #25401.20 April 17, 2026 Technical Information Report Section IV, Page 18 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 | f. 425.778.5536 www.cgengineering.com Pervious Land Use acre A B, Lawn, Flat 0.078 Pervious Total 0.078 Impervious Land Use acre DRIVEWAYS FLAT 0.055 SIDEWALKS MOD 0.011 Impervious Total 0.066 Basin Total 0.144 ___________________________________________________________________ Element Flows To: Surface Interflow Groundwater Gravel Trench Bed 1 Gravel Trench Bed 1 ___________________________________________________________________ Name : Gravel Trench Bed 1 Bottom Length: 89.00 ft. Bottom Width: 5.00 ft. Trench bottom slope 1: 0 To 1 Trench Left side slope 0: 0 To 1 Trench right side slope 2: 0 To 1 Material thickness of first layer: 3 Pour Space of material for first layer: 0.3 Material thickness of second layer: 0 Pour Space of material for second layer: 0 Material thickness of third layer: 0 Pour Space of material for third layer: 0 Infiltration On Infiltration rate: 1.2 Infiltration safety factor: 1 Total Volume Infiltrated (ac-ft.): 10.374 Total Volume Through Riser (ac-ft.): 0.001 Total Volume Through Facility (ac-ft.): 10.375 Percent Infiltrated: 99.99 Total Precip Applied to Facility: 0 Total Evap From Facility: 0 Discharge Structure Riser Height: 2.95 ft. Riser Diameter: 12 in. Element Flows To: Outlet 1 Outlet 2 ___________________________________________________________________ Gravel Trench Bed Hydraulic Table Stage(feet) Area(ac.) Volume(ac-ft.) Discharge(cfs) Infilt(cfs) 0.0000 0.010 0.000 0.000 0.000 Schuder Residence - CG #25401.20 April 17, 2026 Technical Information Report Section IV, Page 19 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 | f. 425.778.5536 www.cgengineering.com 0.0333 0.010 0.000 0.000 0.012 0.0667 0.010 0.000 0.000 0.012 0.1000 0.010 0.000 0.000 0.012 0.1333 0.010 0.000 0.000 0.012 0.1667 0.010 0.000 0.000 0.012 0.2000 0.010 0.000 0.000 0.012 0.2333 0.010 0.000 0.000 0.012 0.2667 0.010 0.000 0.000 0.012 0.3000 0.010 0.000 0.000 0.012 0.3333 0.010 0.001 0.000 0.012 0.3667 0.010 0.001 0.000 0.012 0.4000 0.010 0.001 0.000 0.012 0.4333 0.010 0.001 0.000 0.012 0.4667 0.010 0.001 0.000 0.012 0.5000 0.010 0.001 0.000 0.012 0.5333 0.010 0.001 0.000 0.012 0.5667 0.010 0.001 0.000 0.012 0.6000 0.010 0.001 0.000 0.012 0.6333 0.010 0.001 0.000 0.012 0.6667 0.010 0.002 0.000 0.012 0.7000 0.010 0.002 0.000 0.012 0.7333 0.010 0.002 0.000 0.012 0.7667 0.010 0.002 0.000 0.012 0.8000 0.010 0.002 0.000 0.012 0.8333 0.010 0.002 0.000 0.012 0.8667 0.010 0.002 0.000 0.012 0.9000 0.010 0.002 0.000 0.012 0.9333 0.010 0.002 0.000 0.012 0.9667 0.010 0.003 0.000 0.012 1.0000 0.010 0.003 0.000 0.012 1.0333 0.010 0.003 0.000 0.012 1.0667 0.010 0.003 0.000 0.012 1.1000 0.010 0.003 0.000 0.012 1.1333 0.010 0.003 0.000 0.012 1.1667 0.010 0.003 0.000 0.012 1.2000 0.010 0.003 0.000 0.012 1.2333 0.010 0.003 0.000 0.012 1.2667 0.010 0.003 0.000 0.012 1.3000 0.010 0.004 0.000 0.012 1.3333 0.010 0.004 0.000 0.012 1.3667 0.010 0.004 0.000 0.012 1.4000 0.010 0.004 0.000 0.012 1.4333 0.010 0.004 0.000 0.012 1.4667 0.010 0.004 0.000 0.012 1.5000 0.010 0.004 0.000 0.012 1.5333 0.010 0.004 0.000 0.012 1.5667 0.010 0.004 0.000 0.012 1.6000 0.010 0.004 0.000 0.012 1.6333 0.010 0.005 0.000 0.012 1.6667 0.010 0.005 0.000 0.012 1.7000 0.010 0.005 0.000 0.012 1.7333 0.010 0.005 0.000 0.012 1.7667 0.010 0.005 0.000 0.012 1.8000 0.010 0.005 0.000 0.012 1.8333 0.010 0.005 0.000 0.012 1.8667 0.010 0.005 0.000 0.012 1.9000 0.010 0.005 0.000 0.012 Schuder Residence - CG #25401.20 April 17, 2026 Technical Information Report Section IV, Page 20 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 | f. 425.778.5536 www.cgengineering.com 1.9333 0.010 0.005 0.000 0.012 1.9667 0.010 0.006 0.000 0.012 2.0000 0.010 0.006 0.000 0.012 2.0333 0.010 0.006 0.000 0.012 2.0667 0.010 0.006 0.000 0.012 2.1000 0.010 0.006 0.000 0.012 2.1333 0.010 0.006 0.000 0.012 2.1667 0.010 0.006 0.000 0.012 2.2000 0.010 0.006 0.000 0.012 2.2333 0.010 0.006 0.000 0.012 2.2667 0.010 0.006 0.000 0.012 2.3000 0.010 0.007 0.000 0.012 2.3333 0.010 0.007 0.000 0.012 2.3667 0.010 0.007 0.000 0.012 2.4000 0.010 0.007 0.000 0.012 2.4333 0.010 0.007 0.000 0.012 2.4667 0.010 0.007 0.000 0.012 2.5000 0.010 0.007 0.000 0.012 2.5333 0.010 0.007 0.000 0.012 2.5667 0.010 0.007 0.000 0.012 2.6000 0.010 0.008 0.000 0.012 2.6333 0.010 0.008 0.000 0.012 2.6667 0.010 0.008 0.000 0.012 2.7000 0.010 0.008 0.000 0.012 2.7333 0.010 0.008 0.000 0.012 2.7667 0.010 0.008 0.000 0.012 2.8000 0.010 0.008 0.000 0.012 2.8333 0.010 0.008 0.000 0.012 2.8667 0.010 0.008 0.000 0.012 2.9000 0.010 0.008 0.000 0.012 2.9333 0.010 0.009 0.000 0.012 2.9667 0.010 0.009 0.022 0.012 3.0000 0.010 0.009 0.118 0.012 ___________________________________________________________________ ___________________________________________________________________ ANALYSIS RESULTS Stream Protection Duration ___________________________________________________________________ Predeveloped Landuse Totals for POC #1 Total Pervious Area:0.144 Total Impervious Area:0 ___________________________________________________________________ Mitigated Landuse Totals for POC #1 Total Pervious Area:0.078 Total Impervious Area:0.066 ___________________________________________________________________ Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.000122 5 year 0.000185 Schuder Residence - CG #25401.20 April 17, 2026 Technical Information Report Section IV, Page 21 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 | f. 425.778.5536 www.cgengineering.com 10 year 0.000236 25 year 0.000313 50 year 0.00038 100 year 0.000455 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0 5 year 0 10 year 0 25 year 0 50 year 0 100 year 0 ___________________________________________________________________ Stream Protection Duration POC #1 The Facility PASSED The Facility PASSED. Flow(cfs) Predev Mit Percentage Pass/Fail 0.0001 3044 6 0 Pass 0.0001 2753 6 0 Pass 0.0001 2458 6 0 Pass 0.0001 2201 6 0 Pass 0.0001 1972 6 0 Pass 0.0001 1691 6 0 Pass 0.0001 1501 6 0 Pass 0.0001 1354 6 0 Pass 0.0001 1208 6 0 Pass 0.0001 1009 6 0 Pass 0.0001 853 6 0 Pass 0.0001 699 6 0 Pass 0.0001 577 6 1 Pass 0.0001 472 6 1 Pass 0.0001 354 6 1 Pass 0.0001 259 6 2 Pass 0.0001 156 6 3 Pass 0.0001 52 6 11 Pass 0.0001 26 6 23 Pass 0.0001 26 6 23 Pass 0.0001 26 6 23 Pass 0.0001 26 6 23 Pass 0.0001 25 6 24 Pass 0.0001 25 6 24 Pass 0.0001 24 6 25 Pass 0.0001 23 6 26 Pass 0.0001 23 6 26 Pass 0.0001 23 6 26 Pass 0.0002 22 6 27 Pass 0.0002 22 6 27 Pass 0.0002 22 6 27 Pass 0.0002 21 6 28 Pass 0.0002 21 6 28 Pass 0.0002 21 6 28 Pass 0.0002 21 6 28 Pass Schuder Residence - CG #25401.20 April 17, 2026 Technical Information Report Section IV, Page 22 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 | f. 425.778.5536 www.cgengineering.com 0.0002 19 6 31 Pass 0.0002 19 6 31 Pass 0.0002 18 6 33 Pass 0.0002 18 6 33 Pass 0.0002 18 6 33 Pass 0.0002 16 6 37 Pass 0.0002 16 6 37 Pass 0.0002 16 6 37 Pass 0.0002 16 6 37 Pass 0.0002 16 6 37 Pass 0.0002 15 6 40 Pass 0.0002 15 6 40 Pass 0.0002 15 6 40 Pass 0.0002 14 6 42 Pass 0.0002 13 6 46 Pass 0.0002 13 6 46 Pass 0.0002 13 6 46 Pass 0.0002 13 6 46 Pass 0.0002 13 6 46 Pass 0.0002 13 6 46 Pass 0.0002 12 6 50 Pass 0.0002 12 6 50 Pass 0.0002 12 6 50 Pass 0.0002 11 6 54 Pass 0.0003 11 6 54 Pass 0.0003 11 6 54 Pass 0.0003 11 6 54 Pass 0.0003 10 6 60 Pass 0.0003 10 6 60 Pass 0.0003 9 6 66 Pass 0.0003 9 6 66 Pass 0.0003 9 6 66 Pass 0.0003 9 6 66 Pass 0.0003 9 6 66 Pass 0.0003 8 6 75 Pass 0.0003 8 6 75 Pass 0.0003 8 6 75 Pass 0.0003 8 6 75 Pass 0.0003 8 6 75 Pass 0.0003 8 6 75 Pass 0.0003 8 6 75 Pass 0.0003 8 6 75 Pass 0.0003 8 6 75 Pass 0.0003 8 6 75 Pass 0.0003 8 6 75 Pass 0.0003 8 6 75 Pass 0.0003 8 6 75 Pass 0.0003 8 6 75 Pass 0.0003 8 6 75 Pass 0.0003 8 6 75 Pass 0.0003 8 6 75 Pass 0.0003 8 6 75 Pass 0.0003 8 6 75 Pass 0.0003 8 6 75 Pass 0.0003 8 6 75 Pass 0.0004 8 6 75 Pass 0.0004 8 6 75 Pass Schuder Residence - CG #25401.20 April 17, 2026 Technical Information Report Section IV, Page 23 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 | f. 425.778.5536 www.cgengineering.com 0.0004 8 6 75 Pass 0.0004 8 6 75 Pass 0.0004 8 6 75 Pass 0.0004 8 6 75 Pass 0.0004 8 6 75 Pass 0.0004 8 6 75 Pass 0.0004 8 6 75 Pass 0.0004 8 5 62 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 Gravel Trench Bed 1 POC N 9.44 N 100.00 Total Volume Infiltrated 9.44 0.00 0.00 100.00 0.00 0% No Treat. Credit Compliance with LID Standard 8 Duration Analysis Result = Passed ___________________________________________________________________ ___________________________________________________________________ CHANGES TO PERLND AND IMPLND PARAMETER VALUES. A Total of 0 changes have been made. PERLND NAME Parameter Name Original Value New Value No PERLND changes have been made.IMPLND NAME Parameter Name Original Value New Value IMPLND 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. 2005-2026; All Rights Reserved. Schuder Residence - CG #25401.20 April 17, 2026 Technical Information Report Section V, Page 1 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 | f. 425.778.5536 www.cgengineering.com TIR Section V – Conveyance System Analysis and Design TIR Section V Summary: Narrative Per Core Requirement #4, new pipe systems shall be designed with sufficient capacity to convey and contain the 25-year peak flow. Conveyance capacity shall be demonstrated using the methods in Chapter 4 of the CORSWDM. Verification of capacity and performance must be provided for each element of the conveyance system. The analysis must show design velocities and flows for all drainage facilities within the development, as well as those off-site that are affected by the development. The conveyance system will consist of at least a 4” PVC pipes for the house’s footing drains. A 6” PVC pipe for the house’s roof drains is typical. Roof runoff will be piped from the roof drains to proposed catch basins to the south of the proposed addition and DADUs then convey runoff to the onsite Infiltration trench. See Figures V-1 and V-2 on the following pages for calculations for the on-site conveyance pipes. Figure V-1 shows an image of the spreadsheet used for the Rational Method to calculate the 25-year flow rate for runoff from the roof. Q25 = 0.39 cfs. Figure V-2 shows an image of the spreadsheet used to develop a conveyance capacity table using Manning’s Equation. Normally, a roof drain is sized at 6”. This is more than sufficient as the table shows the capacity of a 6” PVC pipe sloping at 0.5% is 0.49 cfs which more than enough for the 25-year flow rate. Thus, it is recommended that 6” pipes be used to ensure sufficient slope. Therefore, the conveyance pipes are expected to be sufficient. Schuder Residence - CG #25401.20 April 17, 2026 Technical Information Report Section V, Page 2 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 | f. 425.778.5536 www.cgengineering.com Figure V-I: Rational Method Calculations Schuder Residence - CG #25401.20 April 17, 2026 Technical Information Report Section V, Page 3 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 | f. 425.778.5536 www.cgengineering.com Figure V-2: Conveyance capacity values based on Manning’s Equation Schuder Residence - CG #25401.20 April 17, 2026 Technical Information Report Section VI, Page 1 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 | f. 425.778.5536 www.cgengineering.com TIR Section VI – Special Reports and Studies TIR Section VI Summary: Narrative The following reports are provided in this section: 1. Stormwater Infiltration Considerations by Geotech Consultants, Inc. dated December 5, 2025. December 5, 2025 JN 25326 GEOTECH CONSULTANTS, INC. J & M Remodel 4701 Southwest Admiral Way, #215 Seattle, Washington 98116 Attention: Justin Schuder via email: justin@jandmremodel.com Subject: Stormwater Infiltration Considerations Proposed Residential Project 1632 Aberdeen Avenue Northeast Renton, Washington Greetings: This report presents the findings and recommendations of our geotechnical engineering study for the site of the proposed residential project to be located at 1632 Aberdeen Avenue Northeast in Renton. The scope of our services consisted of exploring site surface and subsurface conditions, conducting a small Pilot Infiltration Test (PIT), and then developing this report to provide recommendations for onsite stormwater infiltration. This work was authorized by your acceptance of our proposal, P-12028, dated October 16, 2025. We were provided with a preliminary site plan of the project, which was developed by 2S Design and dated October, 2025 and is overlaid onto a topographic survey of the property. Based on this site plan, we understand that a garage addition will be constructed onto the eastern side of an existing residence located on the western end of the property, and two new detached dwelling units will be constructed on the eastern half of the property. The existing driveway in the southwest corner of the property will be extended along the southern property line to provide access to the two new dwellings. We understand that the proposed residence addition and two new buildings will have lowest floors near the existing ground surface. We understand that onsite infiltration of collected stormwater is proposed for the project and anticipate the infiltration system will be located on the central and/or eastern portions of the property. If the scope of the project changes from what we have described above, we should be provided with revised plans in order to determine if modifications to the recommendations and conclusions of this report are warranted. SITE CONDITIONS SURFACE The Vicinity Map, Plate 1, illustrates the general location of the site in the northeastern portion of Renton. The long, narrow, rectangular-shaped subject site has 60 feet of frontage along the eastern side of Aberdeen Avenue Northeast, and extends a depth of 252 feet to the east. The subject property and general surrounding area are essentially flat. Residential parcels containing single- family residences border the subject site to the north, south, and east. J & M Remodel JN 25326 December 5, 2025 Page 2 GEOTECH CONSULTANTS, INC. The western end of the property is developed with a two-story residence that appears to include a shallow crawlspace. An asphalt driveway connects to Aberdeen Avenue Northeast in the southwest corner of the property and extends east between the southern property line and the southern perimeter of the residence. A small wooden deck wraps around the southeast corner of the residence, and a concrete patio extends off the eastern end of the deck. East of the northern end of the residence is small shed. The remainder of the property is covered with grass and a few scattered small deciduous trees. As noted above, the neighboring properties to the north, south, and east are developed with single- family residences. The northern and eastern adjacent residences have relatively large setbacks from the subject site. The residence to the south overlies a crawlspace, and has an approximate setback of 9 to 10 feet from the subject site. A concrete retaining wall on the southern adjacent property is located along the western approximately 75 feet of the shared property line with the subject site, which retains the neighbor’s driveway, which is elevated approximately 2.5 feet above the subject site. SUBSURFACE The subsurface conditions were explored by excavating two test pits near the central portion of the site at the approximate locations shown on the Site Exploration Plan, Plate 2. Our exploration program was based on the proposed construction, anticipated subsurface conditions and those encountered during exploration, and the scope of work outlined in our proposal. The test pits were excavated on October 31, 2025 with a small rubber-tracked excavator. A geotechnical engineer from our staff observed the excavation process, logged the test pits, and obtained representative samples of the soil encountered. "Grab" samples of selected subsurface soil were collected from the backhoe bucket. The Test Pit Logs are attached to this report as Plate 3. Soil Conditions The test pits encountered approximately 1.5 feet of loose silty sand fill soils with gravel, organics, and occasional plastic, metal, and glass debris overlying the remnant topsoil layer. Loose, native sand with silt and trace organics was encountered below the remnant topsoil became medium-dense to dense below 4 feet with a slightly increased silt content. Below 5.5 feet, occasional slightly silty lenses were observed within the sand. Test Pit 1 was terminated at a depth of 10 feet in the native sand. Test Pit 2 was excavated to only a depth of 4 feet beneath the ground surface because a small Pilot Infiltration Test (PIT) was conducted at this depth. Groundwater Conditions No groundwater seepage, or indications of groundwater, were observed in the test pits. The stratification lines on the logs represent the approximate boundaries between soil types at the exploration locations. The actual transition between soil types may be gradual, and subsurface conditions can vary between exploration locations. The logs provide specific subsurface information only at the locations tested. The relative densities and moisture descriptions indicated on the test pit logs are interpretive descriptions based on the conditions observed during excavation. J & M Remodel JN 25326 December 5, 2025 Page 3 GEOTECH CONSULTANTS, INC. The compaction of test pit backfill was not in the scope of our services. The test pits were backfilled with excavated soil that was lightly tamped into place. Loose soil will therefore be found in the area of the test pits. If this presents a problem, the backfill will need to be removed and replaced with structural fill during construction. PILOT INFILTRATION TESTING In order to assess the infiltration capacity of the site soils, we conducted a Pilot Infiltration Test (PIT) near the central portion of the site. The initial portion of the test is to presoak the base of the test pit that the PIT was conduction. During the presoak period, we were unable to generate a water head above the base of the test pit because the rate of infiltration exceeded the flowrate of the available water source. After the presoak period was finished, we measured the flow rate of the water source at 3.4 gallons/minute. At this rate, only approximately 2 inches of water head was achieved over a base of the test pit. Based on the base area of the test pit of 10.6 square feet (sf) and the measured flow rate, we calculated the measured infiltration rate at the base of the test pit of 30.8 inches/hour. Information regarding this testing is shown in the attached PIT checklist. However, calculating in the use of a more conservative but typical, 12-square-foot base of the test pit, we obtained a more conservative but accurate measured infiltration rate (Imeasured) of 27.3 inches/hour. CONCLUSIONS AND RECOMMENDATIONS Section 5.2.1 of the 2022 City of Renton Surface Water Design Manual requires the design infiltration rate (Idesign) be calculated by applying correction factors to the measured infiltration rate. The correction factors are summarized below: - Ftesting accounts for uncertainties in the testing methods. For the small and large scale Pilot Infiltration Test (PIT), Ftesting = 0.50. - Fgeometry accounts for the influence of facility geometry and depth to the water table or impervious strata on the actual infiltration rate. A shallow water table or impervious layer will reduce the effective infiltration rate of a large pond, but this will not be reflected in a small scale test. Clearly, a large pond built over a thin pervious stratum with a shallow water table will not function as well as the same pond built over a thick pervious stratum with a deep water table. Fgeometry must be between 0.25 and 1.0 as determined by the following equation: Fgeometry = 4 D/W + 0.05 (5-12) Where D = depth from the bottom of the proposed facility to the maximum wet-season water table or nearest impervious layer, whichever is less W = width of the facility - Fplugging accounts for reductions in infiltration rates over the long term due to plugging of soils. This factor is: • 0.7 for loams and sandy loams • 0.8 for fine sands and loamy sands • 0.9 for medium sands • 1.0 for coarse sands or cobbles, or any soil type in an infiltration facility preceded by a water quality facility. J & M Remodel JN 25326 December 5, 2025 Page 4 GEOTECH CONSULTANTS, INC. Based on the soils encountered beneath the subject site, our observations of the site conditions and topography, our experience with other projects in the area, and the test methods used, the following correction factors were used to determine the Idesign: Ftesting = 0.5 Fgeometry = 0.7 Fplugging = 0.8 Finally, Section 5.2.1 states the Idesign is calculated as follows: Design Infiltration Rate (Idesign) = Measured Infiltration Rate (Imeasured) x Ftesting x Fgeometry x Fplugging Idesign = 27.3 in/hr x 0.50 x 0.70 x 0.80 = 7.6 inches/hour We recommend the project civil engineer utilize this Idesign to design the infiltration system in the central or eastern portions of the subject site. However, a few additional site factors should be taken into consideration in the design. The test pits conducted in the central area of the site found about 1.5 to 2 feet of loose un-engineered fill soils and the original topsoil layer overtop of the permeable native sands. In addition, evidence of an old septic drain field was observed in the near-surface fill soils. The bottom of the proposed infiltration system will need to be located beneath the near-surface un-engineered fill and topsoil, and into the underlying native sands. Therefore, the bottom of the infiltration system should be at least 2 feet below the existing ground surface. LIMITATIONS The conclusions and recommendations contained in this report are based on site conditions as they existed at the time of our exploration and assume that the soil and groundwater conditions encountered in the test pits are representative of subsurface conditions on the site. If the subsurface conditions encountered during construction are significantly different from those observed in our explorations, we should be advised at once so that we can review these conditions and reconsider our recommendations where necessary. Unanticipated conditions are commonly encountered on construction sites and cannot be fully anticipated by merely taking samples in test pits. Subsurface conditions can also vary between exploration locations. Such unexpected conditions frequently require making additional expenditures to attain a properly constructed project. It is recommended that the owner consider providing a contingency fund to accommodate such potential extra costs and risks. This is a standard recommendation for all projects. This report has been prepared for the exclusive use of J & M Remodel and its representatives for specific application to this project and site. Our conclusions and recommendations are professional opinions derived in accordance with our understanding of current local standards of practice, and within the scope of our services. No warranty is expressed or implied. The scope of our services does not include services related to construction safety precautions, and our recommendations are not intended to direct the contractor's methods, techniques, sequences, or procedures, except as specifically described in our report for consideration in design. ADDITIONAL SERVICES In addition to reviewing the final plans, Geotech Consultants, Inc. should be retained to provide geotechnical consultation, testing, and observation services during construction. This is to confirm J & M Remodel JN 25326 December 5, 2025 Page 5 GEOTECH CONSULTANTS, INC. that subsurface conditions are consistent with those indicated by our exploration, to evaluate whether earthwork and foundation construction activities comply with the general intent of the recommendations presented in this report, and to provide suggestions for design changes in the event subsurface conditions differ from those anticipated prior to the start of construction. However, our work would not include the supervision or direction of the actual work of the contractor and its employees or agents. Also, job and site safety, and dimensional measurements, will be the responsibility of the contractor. During the construction phase, we will provide geotechnical observation and testing services when requested by you or your representatives. Please be aware that we can only document site work we actually observe. It is still the responsibility of your contractor or on-site construction team to verify that our recommendations are being followed, whether we are present at the site or not. The following plates are attached to complete this report: Plate 1 Vicinity Map Plate 2 Site Exploration Plan Plate 3 Test Pit Logs Attachment PIT Checklist We appreciate the opportunity to be of service on this project. Please contact us if you have any questions, or if we can be of further assistance. Respectfully submitted, GEOTECH CONSULTANTS, INC. Adam S. Moyer Geotechnical Engineer 12/05/2025 D. Robert Ward, P.E. Principal ASM/DRW:kg Job No:Date:Plate: 25326 Dec. 2025 GEOTECH CONSULTANTS, INC. 1632 Aberdeen Aveue Northeast Renton, Washington VICINITY MAP (Source: King County iMap) 1 SITE Job No:Date:Plate: 25326 Dec. 2025 GEOTECH CONSULTANTS, INC. 1632 Aberdeen Aveue Northeast Renton, Washington SITE EXPLORATION PLAN 2 No Scale Legend: Test LocationPit TP-1 TP-2 (PIT) Job Date:Plate: 25326 GEOTECHCONSULTANTS, INC. TEST PIT LOG Dec. 2025 Logged by: 1632 Aberdeen Aveue Northeast Renton, Washington ASM Dark-brown silty SAND with gravel, organics, metal, plastic, and glass debris, fine to medium-grained, moist, loose (FILL) TEST PIT 1 * Test Pit terminated at 10 feet on , 2025.October 31 * No groundwater seepage was observed during excavation. * No caving observed during excavation. 3 Description Description 5 10 5 10 TEST PIT 2 * Test Pit terminated at 4 feet on 31, 2025.October * No groundwater seepage was observed during excavation. * No caving observed during excavation. FILL Reddish-brown SAND with silt and trace organics, fine-grained, dry, loose, -becomes gray-brown, fine to medium-grained, moist, medium dense to dense, slight increase in silt content SP SP SM -occasional slightly silty lenses Remnant Topsoil Dark-brown silty SAND with gravel, organics and occasional plastic debris, fine to medium-grained, moist, loose (FILL) Remnant TopsoilReddish-brown SAND with silt and trace organics, fine-grained, moist, loose -becomes gray-brown, with trace silt, medium dense to denseSP FILL -becomes brown, no organics -becomes brown, no organics Pilot Infiltration Test (PIT) Checklist Call before you dig – Utility Locates 811 Project Address: _________________________________________ Date: ____________________________ Permit Number: _____________________ Other Project Information: ___ ______ __________ This Infiltration Test was performed by: Company Name: ____________________________ Primary Contact Name: ___________________________ Phone Number: _____________________________ Email Address: __________________________________ Include site map or drainage control plan, with test locations clearly marked. The intent of this checklist is to provide a summary of stormwater BMP infiltration testing requirements associated with the Pilot Infiltration Test (PIT). This checklist does not preclude the use of professional judgment to evaluate and manage risk associated with design, construction, and operation of infiltration BMPs. Justification for testing procedures that deviate from the minimum investigation requirements specified in Appendix D shall be documented in a stamped and signed letter from a State of Washington licensed professional (licensed professional engineer, engineering geologist, geologist, or hydrogeologist) who has experience in infiltration and groundwater testing and infiltration facility design. Before you start call Utility Locates 811 to request locates of utilities at your site. SMALL PILOT INFILTRATION TEST (SMALL PIT) AND LARGE PILOT INFILTRATION TEST (LARGE PIT): Note: The test methods outlined below may be modified due to site conditions if recommended by the licensed professional and the reasoning is documented in the testing report. 1.Indicate type of test: Small PIT Large PIT 2.Date and time of tests: ______________________________________________________ 3.Is the infiltration test within the footprint of the proposed infiltration facility? (Yes / No) 4.If “no,” is testing being conducted within 50 feet of the proposed infiltration facility? (Yes / No) Explain why: __________________________________________________________________ Page 1 OF _____ ) Yes 1632 Aberdeen Avenue Northeast, Renton 10/31/25 JN 25326 - J & M Remodel Geotech Consultants Inc Adam Moyer 425-747-5618 adamm@geotechnw.com ✔ 10/31/25 @ 10:30 The PIT was completed within 50 feet of the anticipated infiltration location 5.What is the total proposed impervious area (does not include permeable pavement surfaces) to be infiltrated on the site? ___________________ ft2 (Note: acceptance testing is required if testing was performed greater than 50 feet from the proposed infiltration facility, and greater than 5,000 ft2 infiltrated on the site [see City of Seattle Stormwater Manual, Volume 3, Section 3.2].) 6.Dig an infiltration test pit 7.Test pit excavated to bottom elevation of the proposed infiltration facility (Yes / No) (See City of Seattle Stormwater Manual, Appendix D for additional details.) 8.Test pit surface dimensions (ft): Length: __________ Width: __________ Depth: __________ 9.Test pit bottom dimensions (ft): Length: __________ Width: __________ 10.Test pit bottom area (ft2): __________ 11.Small PIT only: Is the surface area of the test pit bottom at least 12 ft 2? (Yes / No) 12.Large PIT only: Is the surface area of the test pit bottom at least at least 32 ft 2? (Yes / No) a. If “no,” indicate why: ___________________________________________________ 13.Large PIT only: The test pit bottom area should be as close to the bottom area of the proposed infiltration facility as is feasible. a. Bottom area of proposed infiltration facility: __________ ft 2 b. Bottom area of test pit: __________ ft 2 14.Identify device used to measure water level in test pit: Pressure transducer (recommended for areas with slow draining soils), or Vertical rod (min 5 ft long, ½-inch increments, placed in center of pit) 15.Identify method of delivering water to the bottom of the test pit (e.g., rigid pipe with a splash plate): _______________________________________________________________________ (The method of delivery must reduce erosion in the test pit that could cause clogging of the infiltration receptor) 16. Testing Procedure: a.Pre-soak period: Add water to maintain water level at least 12 inches above the bottom of the test pit for at least 6 hours. Record the time and depth of water hourly in the table below. Time of Measurement (hh:mm) Depth of Water (inches) b.Steady-state period: The steady-state data is used to establish the measured infiltration rate (see step 17) i. Add water to the test pit at a rate that will maintain a depth of 12 inches above the bottom of the test pit for 1 full hour. During this hour, record the time, depth of water, cumulative volume, and instantaneous flow rate every 15-minutes in the table below. ii. Calculate the infiltration rate for each 15-minute interval. First convert the flow rate to in 3/hr and the test pit bottom area (recorded in step 10) into in2. Divide the flow rate by the bottom area and record the result in the table below. Page 2 OF _____ Yes ✔ 434 43 12 ✔ rigid pipe with a splash plate 00:30 2 01:00 2 01:30 2 02:00 2 03:00 2 04:00 2 05:00 2 06:00 2 Time of Measurement (hh:mm) Depth of Water (inches) Cumulative Volume (gallons) Flow Rate (gpm) Infiltration Rate (in/hr) --- --- --- 1 gallon = 231 in3, 1 ft2 = 144 in2 c.Falling head period: The falling head data is used to confirm the measured infiltration rate calculated from the steady- state data. i. At the end of the steady-state period, turn off the water and immediately record the time and depth of water in the table below. Record the time and depth of water every 15-minutes for a minimum of 1 hour, or until the pit is empty. (Note: in areas with slow draining soils, a pressure transducer is recommended to improve the accuracy of change in depth readings. In addition, users are encouraged to extend the testing period and use longer intervals to improve accuracy.) ii. Calculate the infiltration rate for each 15-minute interval (change in depth at each interval x 4) and record the results in the table below. Alternatively, users may also record the total time for fixed intervals of changes in depth, and use those values to compute the infiltration rates. Time of Measurement (15-minute minimum intervals) Depth of Water (inches) Infiltration Rate (in/hr) --- d.Check for high groundwater / immediate groundwater mounding: 1.Within 24 hours after the falling head period, excavate the bottom of the pit (Minimum excavation depths are provided in the City of Seattle Stormwater Manual, Appendix D, Section D-3.3 Step 9, and Section D-2.) Is standing water or seepage visible in the excavation hole? (Yes / No) If “yes,” record depth: ________ Note: Additional Groundwater Monitoring requirements may apply. 17. Data Analysis/“Measured Infiltration Rate” Selection (use the falling head data to confirm the measured Page 3 OF _____ Falling Head was not conducted due to inability to establish sufficient pressure head. 00:00 2 00:15 2 3.4 27.3 00:30 2 3.4 27.3 00:45 2 3.4 27.3 01:00 2 3.4 27.3 00:00 00:15 00:30 00:45 01:00 infiltration rate calculated from the steady- state data): a. Steady-state measured infiltration rate: Provide the lowest infiltration rate from steady-state table above: _____________________ in/hr b. Selected “Measured Infiltration Rate” _____________________ in/hr (Include an explanation if the selected rate deviates from the steady-state rate in step 16a.) _____________________________________________________________________________ c. If the lowest measured infiltration rate is less than the minimum rate associated with an infiltration BMP, that BMP cannot be used. d. If the measured infiltration rate is less than all minimum infiltration rates for infiltration BMPs (see Table 1 in the Reference Tables at the end of this document), no further investigation is required. 18. Calculate “Design Infiltration Rate”: The design infiltration rate shall be calculated by applying the appropriate correction factorV to the above measured infiltration rate DSelect correction factorV. ECalculate the Design Infiltration Rate below. Design infiltration rate = _________________________x _________________ = _________________in/hr Measured infiltration rate (in/hr) Correction FactorV* *See the report text for more detailed discussion of correction factors 27.3 27.3 ✔27.3 0.5 x 0.7 x 0.8 7.6 Schuder Residence - CG #25401.20 April 17, 2026 Technical Information Report Section VIII, Page 1 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 | f. 425.778.5536 www.cgengineering.com TIR Section VIII – CSWPPP Analysis and Design TIR Section VIII Summary Narrative ESC Measures SWPPS Measures This section of the TIR provides a summary of erosion controls and source controls for the site and serves as a supplement to the erosion control plan civil drawing sheets. In the proposed condition, a new addition will be added to the existing single-family residence along with two new ADU buildings and associated driveway and walkway areas, resulting in 6,643 sf (0.153 ac) of new impervious surfaces on-site. ESC and SWPP measures were chosen per Section D.2 of the 2022 City of Renton Surface Water Design Manual. Less than 1 acre of land will be disturbed and, therefore, the Department of Ecology SWPPP and Construction Stormwater General Permit are not required. ESC Measures The following ESC measures are suggested for each category below: 1. Clearing Limits: To protect adjacent properties, existing trees to stay, and to reduce the area of soil exposed to construction, the limits of construction will be clearly marked before land-disturbing activities begin. The BMPs relevant to marking the clearing limits that will be applied for this project include: • High Visibility Plastic or Metal Fence 2. Cover Measures Exposed and unworked soils shall be stabilized with the application of effective BMPs to prevent erosion throughout the life of the project. Temporary cover shall be installed if an area is to remain unworked for more than seven days during the dry season (May 1 to September 30) or for more than two consecutive working days during the wet season (October 1 to April 30). The suggested BMPs for soil stabilization that shall be used on this project include: • Temporary & Permanent Seeding • Mulching • Nets & Blankets • Plastic Covering 3. Perimeter Protection All stormwater runoff from disturbed areas shall pass through an appropriate sediment removal BMP before leaving the construction site or prior to being discharged. The specific BMPs to be used for controlling sediment on this project include: • Silt Fence Schuder Residence - CG #25401.20 April 17, 2026 Technical Information Report Section VIII, Page 2 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 | f. 425.778.5536 www.cgengineering.com 4. Traffic Area Stabilization The purpose of a stabilized construction entrance is to reduce the amount of sediment transported off site and to reduce erosion of areas disturbed by vehicle traffic. The site contains an existing paved driveway with access from 240th Way NE and NE 64th Ct that can serve the same purposes. An additional traffic area stabilization BMP is not anticipated to be needed. 5. Sediment Retention The site is flat enough and vegetated sufficiently enough that sediment retention is not anticipated to be needed. Sediment transport should be prevented through catch basin protection and the use of silt fence around the downstream work area. Catch basin inserts should be installed in existing catch basins near the site and in proposed catch basins as they are made operable. The BMPs relevant to dust control that will be applied for this project include: • Silt Fence • Catch Basin Insert 6. Surface Water Collection The purpose of surface water control is to collect and convey surface water so that erosion is minimized. The site is flat enough that surface water collection is not anticipated to be needed. To prevent construction surface water from entering neighboring properties or the right-of-way the BMPs will be applied for this project include: • Sediment Trap • Interceptor Swale 7. Dewatering Control Dewatering is not anticipated to be necessary. 8. Dust Control Dust control will be used to minimize wind transport of soil. Water and/or other dust control measures may be used upon approval by the County. The BMPs relevant to dust control that will be applied for this project include: • Dust Control 9. Flow Control Increases in the 2-year and 10-year runoff event is expected to be small due to the size and topography of the site and amount of impervious area proposed. Flow control facilities are not proposed on this site as flow control requirements are not anticipated to be needed for construction. 10. Protect Existing and Proposed Flow Control BMPs The proposed stormwater mitigation system should be protected during construction by placing high visibility plastic or metal fence around it. The BMPs relevant to protecting flow control BMPs that will be applied for this project include: • High visibility plastic or metal fence Schuder Residence - CG #25401.20 April 17, 2026 Technical Information Report Section VIII, Page 3 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 | f. 425.778.5536 www.cgengineering.com 11. Maintain Protective BMPs BMPs will be maintained and repaired as necessary throughout construction. The CSWPP supervisor shall review the site for ESC and SWPPS at least weekly and within 24 hours of significant storms. All temporary erosion and sediment control BMPs will be removed within 30 days after achieving final site stabilization. 12. Manage the Project Projects shall assign a qualified CSWPPP supervisor to be the primary contact for ESC and SWPPP issues and reporting. SWPPS Measures Stormwater pollution prevention standard (SWPPS) measures are required to prevent, reduce, or eliminate the discharge of pollutants to on-site or adjacent stormwater systems. See Appendix D.2.2 of the 2022 CORSWDM for detailed specifications for the implementation of the following SWPPS Measures: • Concrete Handling: Management practices per Section D.2.2.1 “Concrete Handling” shall be utilized to minimize and eliminate concrete, concrete process water, and concrete slurry runoff. • Concrete Washout Area: Prevent or reduce the discharge of pollutants to stormwater from concrete waste by conducting washout in an area designated by the CSWPP Supervisor to prevent pollutants from entering surface waters or ground water. • Sawcutting and Surfacing Pollution Prevention: Utilize these management practices anytime sawcutting or surfacing operations take place. Sawcutting and surfacing operations include, but are not limited to, sawing, coring, grinding, roughening, hydrodemolition, bridge and road surfacing. • Material Delivery, Storage and Containment: These procedures are suitable for use at all construction sites with delivery and storage of the following materials: Petroleum products such as fuel, oil and grease; Soil stabilizers and binders (e.g. Polyacrylamide); Fertilizers, pesticides and herbicides; Detergents; Asphalt and concrete compounds; Hazardous chemicals such as acids, lime, adhesives, paints, solvents and curing compounds; Any other material that may be detrimental if released to the environment. Schuder Residence - CG #25401.20 April 17, 2026 Technical Information Report Section VIII, Page 4 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 | f. 425.778.5536 www.cgengineering.com Figure VIII-1: Sediment Trap Calculations Schuder Residence - CG #25401.20 April 17, 2026 Technical Information Report Section IX, Page 1 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 | f. 425.778.5536 www.cgengineering.com TIR Section IX – Bond Quantities, Facility Summaries, and Declaration of Covenant TIR Section IX Summary: Narrative A Bond Quantities Sheet and Declaration of Covenant is provided with this report. Schuder Residence - CG #25401.20 April 17, 2026 Technical Information Report Section X, Page 1 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 | f. 425.778.5536 www.cgengineering.com TIR Section X – Operation and Maintenance Manual TIR Section X Summary: Narrative Operation and Maintenance Manual This Operation and Maintenance Manual has been created for the Schuder Residence project, located on a 0.348 ac lot at 1632 Aberdeen Ave NE Renton, WA 98056. The proposed storm system consists of catch basins and conveyance pipes. Included in this Operation and Maintenance Manual is an 11”x17” grading and drainage plan sheet showing the location of the system. Please note that this map is generated during the design phase and may not reflect all changes made in permitting and construction. CG Engineering may be contacted for an updated copy of this map once the as-built drawings are completed for the site. The contractor will be responsible for the maintenance and operation of all stormwater structures and BMPs requiring maintenance during construction, and after construction, responsibility will pass to the property owner. Included in this manual are maintenance sheets taken from the 2022 City of Renton Surface Water Design Manual for the following facilities/activities: Catch Basins: Concrete structures with steel grates that collect stormwater runoff from the site and act as junctions for storm conveyance pipes. Catch Basin Inserts: Filter socks/traps to be placed in catch basins to prevent sediment-laden waters from entering the public storm system. Infiltration Trench: Infiltration trenches will be provided to manage stormwater on the site. Vegetation Management: Landscaping can include grading, soil transfer, vegetation removal, pesticide and fertilizer applications, and watering. Stormwater contaminants include toxic organic compounds, heavy metals, oils, total suspended solids, coliform bacteria, fertilizers, and pesticides. Facilities shall be inspected for defects listed in the following facility sheets. Most maintenance tasks are generally reactionary to a defect being found, rather than a matter of constant upkeep. It is generally expected that few to none of these defects will be present upon the yearly inspection of each facility. The facility sheets list the potential conditions warranting maintenance and the expected result following any maintenance. Several engineer’s notes for specific tasks are provided within the facility sheets. Unless otherwise noted on the facility sheets the maintenance tasks should be performed on an “as needed” basis: (a) When the described defect is visible to whomever performs the yearly inspection, (b) Should any defect become apparent between inspections. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 6/22/2022 2022 City of Renton Surface Water Design Manual A-4 NO. 2 – INFILTRATION FACILITIES MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Site Trash and debris Any trash and debris which exceed 1 cubic foot per 1,000 square feet (this is about equal to the amount of trash it would take to fill up one standard size office garbage can). In general, there should be no visual evidence of dumping. Trash and debris cleared from site. Noxious weeds Any noxious or nuisance vegetation which may constitute a hazard to City personnel or the public. Noxious and nuisance vegetation removed according to applicable regulations. No danger of noxious vegetation where City personnel or the public might normally be. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Excessive growth of grass/groundcover Grass or groundcover exceeds 18 inches in height. Grass or groundcover mowed to a height no greater than 6 inches. Infiltration Pond, Top or Side Slopes of Dam, Berm or Embankment Rodent holes Any evidence of rodent holes if facility is acting as a dam or berm, or any evidence of water piping through dam or berm via rodent holes. Rodents removed or destroyed and dam or berm repaired. Tree growth Tree growth threatens integrity of dams, berms or slopes, does not allow maintenance access, or interferes with maintenance activity. If trees are not a threat to dam, berm, or embankment integrity or not interfering with access or maintenance, they do not need to be removed. Trees do not hinder facility performance or maintenance activities. Erosion Eroded damage over 2 inches deep where cause of damage is still present or where there is potential for continued erosion. Any erosion observed on a compacted slope. Slopes stabilized using appropriate erosion control measures. If erosion is occurring on compacted slope, a licensed civil engineer should be consulted to resolve source of erosion. Settlement Any part of a dam, berm or embankment that has settled 4 inches lower than the design elevation. Top or side slope restored to design dimensions. If settlement is significant, a licensed civil engineer should be consulted to determine the cause of the settlement. Infiltration Pond, Tank, Vault, Trench, or Small Basin Storage Area Sediment accumulation If two inches or more sediment is present or a percolation test indicates facility is working at or less than 90% of design. Facility infiltrates as designed. Liner damaged If applicable) Liner is visible or pond does not hold water as designed. Liner repaired or replaced. Infiltration Tank Structure Plugged air vent Any blockage of the vent. Tank or vault freely vents. Tank bent out of shape Any part of tank/pipe is bent out of shape more than 10% of its design shape. Tank repaired or replaced to design. Gaps between sections, damaged joints or cracks or tears in wall A gap wider than ½-inch at the joint of any tank sections or any evidence of soil particles entering the tank at a joint or through a wall. No water or soil entering tank through joints or walls. Infiltration Vault Structure Damage to wall, frame, bottom, and/or top slab Cracks wider than ½-inch, any evidence of soil entering the structure through cracks or qualified inspection personnel determines that the vault is not structurally sound. Vault is sealed and structurally sound. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 2022 City of Renton Surface Water Design Manual 6/22/2022 A-5 NO. 2 – INFILTRATION FACILITIES MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Inlet/Outlet Pipes Sediment accumulation Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment. Trash and debris Trash and debris accumulated in inlet/outlet pipes (includes floatables and non-floatables). No trash or debris in pipes. Damaged inlet/outlet pipe Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering at the joints of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of the inlet/outlet pipe. Access Manhole Cover/lid not in place Cover/lid is missing or only partially in place. Any open manhole requires immediate maintenance. Manhole access covered. Locking mechanism not working Mechanism cannot be opened by one maintenance person with proper tools. Bolts cannot be seated. Self-locking cover/lid does not work. Mechanism opens with proper tools. Cover/lid difficult to remove One maintenance person cannot remove cover/lid after applying 80 lbs of lift. Cover/lid can be removed and reinstalled by one maintenance person. Ladder rungs unsafe Missing rungs, misalignment, rust, or cracks. Ladder meets design standards. Allows maintenance person safe access. Large access doors/plate Damaged or difficult to open Large access doors or plates cannot be opened/removed using normal equipment. Replace or repair access door so it can be opened as designed. Gaps, doesn't cover completely Large access doors not flat and/or access opening not completely covered. Doors close flat; covers access opening completely. Lifting rings missing, rusted Lifting rings not capable of lifting weight of door or plate. Lifting rings sufficient to lift or remove door or plate. Infiltration Pond, Tank, Vault, Trench, or Small Basin Filter Bags Plugged filter bag (if applicable) Filter bag more than 1/2 full. Replace filter bag or redesign system. Infiltration Pond, Tank, Vault, Trench, or Small Basin Pre- settling Ponds and Vaults Sediment accumulation 6" or more of sediment has accumulated. Pre-settling occurs as designed Infiltration Pond, Rock Filter Plugged rock filter High water level on upstream side of filter remains for extended period of time or little or no water flows through filter during heavy rain storms. Rock filter replaced evaluate need for filter and remove if not necessary. Infiltration Pond Emergency Overflow Spillway Rock missing Only one layer of rock exists above native soil in area five square feet or larger, or any exposure of native soil at the top of out flow path of spillway. Rip-rap on inside slopes need not be replaced. Spillway restored to design standards. Tree growth Tree growth impedes flow or threatens stability of spillway. Trees removed. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 6/22/2022 2022 City of Renton Surface Water Design Manual A-10 NO. 5 – CATCH BASINS AND MANHOLES MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITION WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Structure Sediment accumulation Sediment exceeds 60% of the depth from the bottom of the catch basin to the invert of the lowest pipe into or out of the catch basin or is within 6 inches of the invert of the lowest pipe into or out of the catch basin. Sump of catch basin contains no sediment. Trash and debris Trash or debris of more than ½ cubic foot which is located immediately in front of the catch basin opening or is blocking capacity of the catch basin by more than 10%. No Trash or debris blocking or potentially blocking entrance to catch basin. Trash or debris in the catch basin that exceeds 1/3 the depth from the bottom of basin to invert the lowest pipe into or out of the basin. No trash or debris in the catch basin. Dead animals or vegetation that could generate odors that could cause complaints or dangerous gases (e.g., methane). No dead animals or vegetation present within catch basin. Deposits of garbage exceeding 1 cubic foot in volume. No condition present which would attract or support the breeding of insects or rodents. Damage to frame and/or top slab Corner of frame extends more than ¾ inch past curb face into the street (If applicable). Frame is even with curb. Top slab has holes larger than 2 square inches or cracks wider than ¼ inch. Top slab is free of holes and cracks. Frame not sitting flush on top slab, i.e., separation of more than ¾ inch of the frame from the top slab. Frame is sitting flush on top slab. Cracks in walls or bottom Cracks wider than ½ inch and longer than 3 feet, any evidence of soil particles entering catch basin through cracks, or maintenance person judges that catch basin is unsound. Catch basin is sealed and is structurally sound. Cracks wider than ½ inch and longer than 1 foot at the joint of any inlet/outlet pipe or any evidence of soil particles entering catch basin through cracks. No cracks more than 1/4 inch wide at the joint of inlet/outlet pipe. Settlement/ misalignment Catch basin has settled more than 1 inch or has rotated more than 2 inches out of alignment. Basin replaced or repaired to design standards. Damaged pipe joints Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering the catch basin at the joint of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of inlet/outlet pipes. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Inlet/Outlet Pipe Sediment accumulation Sediment filling 20% or more of the pipe. Inlet/outlet pipes clear of sediment. Trash and debris Trash and debris accumulated in inlet/outlet pipes (includes floatables and non-floatables). No trash or debris in pipes. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 2022 City of Renton Surface Water Design Manual 6/22/2022 A-11 NO. 5 – CATCH BASINS AND MANHOLES MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITION WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Inlet/Outlet Pipe cont.) Damaged inlet/outlet pipe Cracks wider than ½-inch at the joint of the inlet/outlet pipes or any evidence of soil entering at the joints of the inlet/outlet pipes. No cracks more than ¼-inch wide at the joint of the inlet/outlet pipe. Metal Grates Catch Basins) Unsafe grate opening Grate with opening wider than 7/8 inch. Grate opening meets design standards. Trash and debris Trash and debris that is blocking more than 20% of grate surface. Grate free of trash and debris. Damaged or missing grate Grate missing or broken member(s) of the grate. Any open structure requires urgent maintenance. Grate is in place and meets design standards. Manhole Cover/Lid Cover/lid not in place Cover/lid is missing or only partially in place. Any open structure requires urgent maintenance. Cover/lid protects opening to structure. Locking mechanism not working Mechanism cannot be opened by one maintenance person with proper tools. Bolts cannot be seated. Self-locking cover/lid does not work. Mechanism opens with proper tools. Cover/lid difficult to remove One maintenance person cannot remove cover/lid after applying 80 lbs. of lift. Cover/lid can be removed and reinstalled by one maintenance person. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 6/22/2022 2022 City of Renton Surface Water Design Manual A-12 NO. 6 – CONVEYANCE PIPES AND DITCHES MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Pipes Sediment & debris accumulation Accumulated sediment or debris that exceeds 20% of the diameter of the pipe. Water flows freely through pipes. Vegetation/root growth in pipe Vegetation/roots that reduce free movement of water through pipes. Water flows freely through pipes. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Damage to protective coating or corrosion Protective coating is damaged; rust or corrosion is weakening the structural integrity of any part of pipe. Pipe repaired or replaced. Damaged pipes Any dent that decreases the cross section area of pipe by more than 20% or is determined to have weakened structural integrity of the pipe. Pipe repaired or replaced. Ditches Trash and debris Trash and debris exceeds 1 cubic foot per 1,000 square feet of ditch and slopes. Trash and debris cleared from ditches. Sediment accumulation Accumulated sediment that exceeds 20% of the design depth. Ditch cleaned/flushed of all sediment and debris so that it matches design. Noxious weeds Any noxious or nuisance vegetation which may constitute a hazard to City personnel or the public. Noxious and nuisance vegetation removed according to applicable regulations. No danger of noxious vegetation where City personnel or the public might normally be. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Excessive vegetation growth Vegetation that reduces free movement of water through ditches. Water flows freely through ditches. Erosion damage to slopes Any erosion observed on a ditch slope. Slopes are not eroding. Rock lining out of place or missing (If applicable) One layer or less of rock exists above native soil area 5 square feet or more, any exposed native soil. Replace rocks to design standards. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 2022 City of Renton Surface Water Design Manual 6/22/2022 A-13 NO. 7 – DEBRIS BARRIERS (E.G., TRASH RACKS) MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITION WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED. Site Trash and debris Trash or debris plugging more than 20% of the area of the barrier. Barrier clear to receive capacity flow. Sediment accumulation Sediment accumulation of greater than 20% of the area of the barrier Barrier clear to receive capacity flow. Structure Cracked, broken, or loose pipe or structure Structure which bars attached to is damaged – pipe is loose or cracked or concrete structure is cracked, broken, or loose. Structure barrier attached to is sound. Bars Incorrect bar spacing Bar spacing exceeds 6 inches. Bars have at most 6 inches spacing. Damaged or missing bars Bars are bent out of shape more than 3 inches. Bars in place with no bends more than ¾ inch. Bars are missing or entire barrier missing. Bars in place according to design. Bars are loose and rust is causing 50% deterioration to any part of barrier. Repair or replace barrier to design standards. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 2022 City of Renton Surface Water Design Manual 6/22/2022 A-17 NO. 11 – GROUNDS (LANDSCAPING) MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Site Trash and debris Any trash and debris which exceed 1 cubic foot per 1,000 square feet (this is about equal to the amount of trash it would take to fill up one standard size office garbage can). In general, there should be no visual evidence of dumping. Trash and debris cleared from site. Noxious weeds Any noxious or nuisance vegetation which may constitute a hazard to City personnel or the public. Noxious and nuisance vegetation removed according to applicable regulations. No danger of noxious vegetation where City personnel or the public might normally be. Contaminants and pollution Any evidence of contaminants or pollution such as oil, gasoline, concrete slurries or paint. Materials removed and disposed of according to applicable regulations. Source control BMPs implemented if appropriate. No contaminants present other than a surface oil film. Excessive growth of grass/groundcover Grass or groundcover exceeds 18 inches in height. Grass or groundcover mowed to a height no greater than 6 inches. Trees and Shrubs Hazard tree identified Any tree or limb of a tree identified as having a potential to fall and cause property damage or threaten human life. A hazard tree identified by a qualified arborist must be removed as soon as possible. No hazard trees in facility. Damaged tree or shrub identified Limbs or parts of trees or shrubs that are split or broken which affect more than 25% of the total foliage of the tree or shrub. Trees and shrubs with less than 5% of total foliage with split or broken limbs. Trees or shrubs that have been blown down or knocked over. No blown down vegetation or knocked over vegetation. Trees or shrubs free of injury. Trees or shrubs which are not adequately supported or are leaning over, causing exposure of the roots. Tree or shrub in place and adequately supported; dead or diseased trees removed. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 6/22/2022 2022 City of Renton Surface Water Design Manual A-38 NO. 25 – DRYWELL BMP MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Preventive Plugging, obstructions Any cause limiting flow into drywell. Drywell able to receive full flow prior to and during wet season. Site Trash and debris Trash or debris that could end up in the drywell is evident. No trash or debris that could get into the drywell can be found. Pipes Plugged inlet The entrance to the pipe is restricted due to sediment, trash, or debris. The entrance to the pipe is not restricted. Vegetation/root growth in pipes Vegetation/roots that reduce free movement of water through pipes. Water flows freely through pipes. Plugged pipe Sediment or other material prevents free flow of water through the pipe. Water flows freely through pipes. Broken pipe or joint leaks Damage to the pipe or pipe joints allowing water to seep out. Pipe does not allow water to exit other than at the outlet. Structure Basin leaks Holes or breaks in the basin allow water to leave the basin at locations other than per design. Basin is sealed and allows water to exit only where designed. Filter Media Plugged filter media Filter media plugged. Flow through filter media is normal. NO. 26 – GRAVEL FILLED INFILTRATION TRENCH BMP MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Preventive Blocking, obstructions Debris or trash limiting flow to infiltration trench. Infiltration trench able to receive full flow prior to and during wet season. Site Trash and debris Trash or debris that could end up in the infiltration trench is evident. No trash or debris that could get into the infiltration trench can be found. Pipes Plugged inlet The entrance to the pipe is restricted due to sediment, trash, or debris. The entrance to the pipe is not restricted. Vegetation/root growth in pipes Vegetation/roots that reduce free movement of water through pipes. Water flows freely through pipes. Plugged pipes Sediment or other material prevents free flow of water through the pipe. Water flows freely through pipes. Broken pipe or joint leaks Damage to the pipe or pipe joints allowing water to seep out. Pipe does not allow water to exit other than at the outlet to the trench. Structure Flow not reaching trench Flows are not getting into the trench as designed. Water enters and exits trench as designed. Cleanout/inspection access does not allow cleaning or inspection of trench The cleanout/inspection access is not available. Cleanout/inspection access is available. Filter Media Plugged filter media Filter media plugged. Flow through filter media is normal. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 6/22/2022 2022 City of Renton Surface Water Design Manual A-40 NO. 28 – NATIVE VEGETATED SURFACE/NATIVE VEGETATED LANDSCAPE BMP MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITION WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Site Trash and debris Trash and debris accumulated on the native vegetated surface/native vegetated landscape site. Native vegetated surface site free of any trash or debris. Vegetation Insufficient vegetation Less than two species each of native trees, shrubs, and groundcover occur in the design area. A minimum of two species each of native trees, shrubs, and groundcover is established and healthy. Poor vegetation coverage Less than 90% if the required vegetated area has healthy growth. A minimum of 90% of the required vegetated area has healthy growth. Undesirable vegetation present Weeds, blackberry, and other undesirable plants are invading more than 10% of vegetated area. Less than 10% undesirable vegetation occurs in the required native vegetated surface area. Vegetated Area Soil compaction Soil in the native vegetation area compacted. Less than 8% of native vegetation area is compacted. Insufficient vegetation Less than 3.5 square feet of native vegetation area for every 1 square foot of impervious surface. A minimum of 3.5 square feet of native vegetation area for every 1 square foot of impervious surface. Excess slope Slope of native vegetation area greater than 15%. Slope of native growth area does not exceed 15%. NO. 29 – PERFORATED PIPE CONNECTIONS BMP MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Preventive Blocking, obstructions Debris or trash limiting flow into perforated pipe system or outfall of BMP is plugged or otherwise nonfunctioning. Outfall of BMP is receiving designed flows from perforated pipe connection. Inflow Inflow impeded Inflow into the perforated pipe is partially or fully blocked or altered to prevent flow from getting into the pipe. Inflow to the perforated pipe is unimpeded. Pipe Trench Area Surface compacted Ground surface over the perforated pipe trench is compacted or covered with impermeable material. Ground surface over the perforated pipe is not compacted and free of any impervious cover. Outflow Outflow impeded Outflow from the perforated pipe into the public drainage system is blocked. Outflow to the public drainage system is unimpeded. Outfall Area Erosion or landslides Existence of the perforated pipe is causing or exasperating erosion or landslides. Perforated pipe system is sealed off and an alternative BMP is implemented. APPENDIX A MAINTENANCE REQUIREMENTS FOR STORMWATER FACILITIES AND ON-SITE BMPS 2022 City of Renton Surface Water Design Manual 6/22/2022 A-47 NO. 38 – SOIL AMENDMENT BMP MAINTENANCE COMPONENT DEFECT OR PROBLEM CONDITIONS WHEN MAINTENANCE IS NEEDED RESULTS EXPECTED WHEN MAINTENANCE IS PERFORMED Soil Media Unhealthy vegetation Vegetation not fully covering ground surface or vegetation health is poor. Yellowing: possible Nitrogen (N) deficiency. Poor growth: possible Phosphorous (P) deficiency. Poor flowering, spotting or curled leaves, or weak roots or stems: possible Potassium K) deficiency. Plants are healthy and appropriate for site conditions Inadequate soil nutrients and structure In the fall, return leaf fall and shredded woody materials from the landscape to the site when possible Soil providing plant nutrients and structure Excessive vegetation growth Grass becomes excessively tall (greater than 10 inches); nuisance weeds and other vegetation start to take over. Healthy turf- “grasscycle” (mulch-mow or leave the clippings) to build turf health Weeds Preventive maintenance Avoid use of pesticides (bug and weed killers), like “weed & feed,” which damage the soil Fertilizer needed Where fertilization is needed (mainly turf and annual flower beds), a moderate fertilization program should be used which relies on compost, natural fertilizers or slow-release synthetic balanced fertilizers Integrated Pest Management (IPM) protocols for fertilization followed Bare spots Bare spots on soil No bare spots, area covered with vegetation or mulch mixed into the underlying soil. Compaction Poor infiltration due to soil compaction To remediate compaction, aerate soil, till to at least 8-inch depth, or further amend soil with compost and re-till If areas are turf, aerate compacted areas and top dress them with 1/4 to 1/2 inch of compost to renovate them If drainage is still slow, consider investigating alternative causes (e.g., high wet season groundwater levels, low permeability soils) Also consider site use and protection from compacting activities No soil compaction Poor infiltration Soils become waterlogged, do not appear to be infiltrating. Facility infiltrating properly Erosion/Scouring Erosion Areas of potential erosion are visible Causes of erosion (e.g., concentrate flow entering area, channelization of runoff) identified and damaged area stabilized regrade, rock, vegetation, erosion control matting).For deep channels or cuts (over 3 inches in ponding depth), temporary erosion control measures in place until permanent repairs can be made Grass/Vegetation Unhealthy vegetation Less than 75% of planted vegetation is healthy with a generally good appearance. Healthy vegetation. Unhealthy plants removed/replaced. Appropriate vegetation planted in terms of exposure, soil and soil moisture. Noxious Weeds Noxious weeds Listed noxious vegetation is present (refer to current County noxious weed list). No noxious weeds present. Schuder Residence - CG #25401.20 April 17, 2026 Technical Information Report Section X, Page 2 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph. 425.778.8500 | f. 425.778.5536 www.cgengineering.com SAMPLE ACTIVITY LOG DATE FACILITY MAINTENANCE PERFORMED RESULTS / NOTES