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Home My WebLink About34_Drainage-ReportKING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL TECHNICAL INFORMATION REPORT (TIR) WORKSHEET 2009 Surface Water Design Manual 1/9/2009 1 Part 1 PROJECT OWNER AND PROJECT ENGINEER Part 2 PROJECT LOCATION AND DESCRIPTION Project Owner ________________________ Phone ______________________________ Address ____________________________ ____________________________________ Project Engineer ______________________ Company ___________________________ Phone ______________________________ Project Name _________________________ DDES Permit # ________________________ Location Township ______________ Range ________________ Section ________________ Site Address __________________________ _____________________________________ Part 3 TYPE OF PERMIT APPLICATION Part 4 OTHER REVIEWS AND PERMITS Landuse Services Subdivison / Short Subd. / UPD Building Services M/F / Commerical / SFR Clearing and Grading Right-of-Way Use Other _______________________ DFW HPA COE 404 DOE Dam Safety FEMA Floodplain COE Wetlands Other ________ Shoreline Management Structural Rockery/Vault/_____ ESA Section 7 Part 5 PLAN AND REPORT INFORMATION Technical Information Report Site Improvement Plan (Engr. Plans) Type of Drainage Review (circle): Date (include revision dates): Date of Final: Full / Targeted / Large Site ___________________ ___________________ ___________________ Type (circle one): Date (include revision dates): Date of Final: Full / Modified / Small Site __________________ __________________ __________________ Part 6 ADJUSTMENT APPROVALS Type (circle one): Standard / Complex / Preapplication / Experimental / Blanket Description: (include conditions in TIR Section 2) ____________________________________________________________________________________ ____________________________________________________________________________________ ____________________________________________________________________________________ Date of Approval: ______________________ KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL TECHNICAL INFORMATION REPORT (TIR) WORKSHEET 2009 Surface Water Design Manual 1/9/2009 2 Part 7 MONITORING REQUIREMENTS Monitoring Required: Yes / No Start Date: _______________________ Completion Date: _______________________ Describe: _________________________________ _________________________________________ _________________________________________ _________________________________________ _________________________________________ Part 8 SITE COMMUNITY AND DRAINAGE BASIN Community Plan : _________________________________ Special District Overlays: __________________________________________________________ Drainage Basin: ___________________________________ Stormwater Requirements: ________________________________________________________ Part 9 ONSITE AND ADJACENT SENSITIVE AREAS River/Stream _______________________ Lake _____________________________ Wetlands ___________________________ Closed Depression ___________________ Floodplain __________________________ Other ______________________________ ___________________________________ Steep Slope ______________________ Erosion Hazard ___________________ Landslide Hazard __________________ Coal Mine Hazard __________________ Seismic Hazard ___________________ Habitat Protection __________________ _________________________________ Part 10 SOILS Soil Type _________________ _________________ _________________ _________________ Slopes _________________ _________________ _________________ _________________ Erosion Potential _________________ _________________ _________________ _________________ High Groundwater Table (within 5 feet) Other ________________________ Sole Source Aquifer Seeps/Springs Additional Sheets Attached KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL TECHNICAL INFORMATION REPORT (TIR) WORKSHEET 2009 Surface Water Design Manual 1/9/2009 3 Part 11 DRAINAGE DESIGN LIMITATIONS REFERENCE Core 2 – Offsite Analysis_________________ Sensitive/Critical Areas___________________ SEPA________________________________ Other_________________________________ _____________________________________ LIMITATION / SITE CONSTRAINT _______________________________________ _______________________________________ _______________________________________ _______________________________________ _______________________________________ Additional Sheets Attached Part 12 TIR SUMMARY SHEET (provide one TIR Summary Sheet per Threshold Discharge Area) Threshold Discharge Area: (name or description) Core Requirements (all 8 apply) Discharge at Natural Location Number of Natural Discharge Locations: Offsite Analysis Level: 1 / 2 / 3 dated:__________________ Flow Control (incl. facility summary sheet) Level: 1 / 2 / 3 or Exemption Number ____________ Small Site BMPs ___________________________________ Conveyance System Spill containment located at: _________________________ Erosion and Sediment Control ESC Site Supervisor: Contact Phone: After Hours Phone: Maintenance and Operation Responsibility: Private / Public If Private, Maintenance Log Required: Yes / No Financial Guarantees and Liability Provided: Yes / No Water Quality (include facility summary sheet) Type: Basic / Sens. Lake / Enhanced Basicm / Bog or Exemption No. ______________________ Landscape Management Plan: Yes / No Special Requirements (as applicable) Area Specific Drainage Requirements Type: CDA / SDO / MDP / BP / LMP / Shared Fac. / None Name: ________________________ Floodplain/Floodway Delineation Type: Major / Minor / Exemption / None 100-year Base Flood Elevation (or range): ______________ Datum: Flood Protection Facilities Describe: Source Control (comm./industrial landuse) Describe landuse: Describe any structural controls: KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL TECHNICAL INFORMATION REPORT (TIR) WORKSHEET 2009 Surface Water Design Manual 1/9/2009 4 Oil Control High-use Site: Yes / No Treatment BMP: ________________________________ Maintenance Agreement: Yes / No with whom? ____________________________________ Other Drainage Structures Describe: Part 13 EROSION AND SEDIMENT CONTROL REQUIREMENTS MINIMUM ESC REQUIREMENTS DURING CONSTRUCTION Clearing Limits Cover Measures Perimeter Protection Traffic Area Stabilization Sediment Retention Surface Water Collection Dewatering Control Dust Control Flow Control MINIMUM ESC REQUIREMENTS AFTER CONSTRUCTION Stabilize Exposed Surfaces Remove and Restore Temporary ESC Facilities Clean and Remove All Silt and Debris, Ensure Operation of Permanent Facilities Flag Limits of SAO and open space preservation areas Other ______________________ Part 14 STORMWATER FACILITY DESCRIPTIONS (Note: Include Facility Summary and Sketch) Flow Control Type/Description Water Quality Type/Description Detention Infiltration Regional Facility Shared Facility Flow Control BMPs Other ________________ ________________ ________________ ________________ ________________ ________________ Biofiltration Wetpool Media Filtration Oil Control Spill Control Flow Control BMPs Other ________________ ________________ ________________ ________________ ________________ ________________ ________________ KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL TECHNICAL INFORMATION REPORT (TIR) WORKSHEET 2009 Surface Water Design Manual 1/9/2009 5 Part 15 EASEMENTS/TRACTS Part 16 STRUCTURAL ANALYSIS Drainage Easement Covenant Native Growth Protection Covenant Tract Other Cast in Place Vault Retaining Wall Rockery > 4’ High Structural on Steep Slope Other Part 17 SIGNATURE OF PROFESSIONAL ENGINEER I, or a civil engineer under my supervision, have visited the site. Actual site conditions as observed were incorporated into this worksheet and the attached Technical Information Report. To the best of my knowledge the information provided here is accurate. Signed/Date i Contents SECTION 1: Project Overview .......................................................................................................... 1 SECTION 2: Core and Special Requirements Summary .................................................................. 3 SECTION 3: Offsite Analysis ............................................................................................................. 4 SECTION 4: Flow Control and water quality Facility Analysis and Design ...................................... 6 SECTION 5: Conveyance System Analysis and Design .................................................................. 10 SECTION 6: Special Reports and Studies ....................................................................................... 12 SECTION 7: Other Permits ............................................................................................................. 12 SECTION 8: CSWPP Analysis and Design ....................................................................................... 12 SECTION 9: Bond Quantities, Facility Summaries, and Declaration of Covenant ......................... 12 SECTION 10: Operations and Maintenance Manual ..................................................................... 12 FIGURES Figure 1 – Vicinity Map Figure 2 – Soils Map Figure 3A & 3B – Downstream Mapping APPENDICIES Appendix A – KCRTS Analysis Appendix B – Operations & Maintenance Manual Appendix C – Geotechnical Report Appendix D – Arborist Report Appendix E – Wetland & Stream Reconnaissance 1 SECTION 1: Project Overview This Technical Information Report is submitted in support of the Renton Subdivision Preliminary Plat. The project site consists of 2 parcels; KC Parcel #’s 0087000265 and 0087000270. The properties are rectangular in shape and are located on the east side of 106th Avenue SE (See Figure 1 - Vicinity Map below). The property is bordered along the north, south, and east by single family residences. The project area is approximately 1.94 acres and is presently developed with 2 single-family residences. The existing buildings and driveways will be removed. Project site improvements will consist of on & off-site infrastructure improvements to support the future construction of 11 single family residential building lots and new public road. Frontage improvements will include the installation of an 8’ wide planter strip and a 5’ wide sidewalk along 106th Avenue SE. Figure 1 – Vicnity Map SITE 2 Soils: The SCS Soils map indicates the site is underlain with AgC (Alderwood) soils. Figure 2 – Soils Map SITE 3 SECTION 2: Core and Special Requirements Summary To obtain preliminary approval with the City of Renton, the relevancy of the 8 core and 6 special requirements per Section 4-6-030 of the Renton Municipal Code (RMC), KCSWDM are required to be addressed: 1. Core Req. #1 – Discharge at natural location A field review of the site-specific topography indicates that the developed drainage will discharge to the natural location situated downstream to the west of the project site. 2. Core Req. #2 – Offsite Analysis An off-site analysis has been prepared for approval by the City of Renton, See Section 3. 3. Core Req. #3 – Flow Control Flow control will be provided for the development via a detention vault. See Section 4. 4. Core Req. #4 – Conveyance System The proposed on-site conveyance and tightline system will route runoff to the existing conveyance system within 106th AVE SE. 5. Core Req. #5 – Erosion & Sediment Control. An erosion and sediment control plan, which will serve to minimize soil erosion/sedimentation during the proposed site construction, will be prepared for approval by the City of Renton. 6. Core Req. #6 – Maintenance and Operations The on-site stormwater system will be maintained by the homeowners. The off-site conveyance systems will be maintained by the City of Renton. See Appendix B. 7. Core Req. #7 – Financial Guarantees & Liability Financial Guarantee & Liability commitments between the property developer and the City of Renton will be established at the time of permit issuance. 8. Core Req. #8 – Water Quality The proposed pollution generating impervious surfaces are greater than the 5,000 SF threshold, therefore water quality treatment is required. The project proposes a combined detention and wetvault system to meet the water quality requirement. 9. Special Req. #1 – Other Adopted Requirements The Renton SWDM was reviewed and there are no additional requirements. 10. Special Req. #2 – Floodplain/Floodway Delineation Per City of Renton mapping the site does not lie within a floodplain or floodway 11. Special Req. #3 – Flood Protection Facilities Not applicable to this project. 12. Special Req. #4 – Source Control Not applicable to this project 13. Special Req. #5 – Oil Control This project is not considered high-use therefore oil control is not applicable to this project. 14. Special Req. #6 – Aquifer Protection Area Not applicable to this project. 4 SECTION 3: Offsite Analysis A field review of the downstream conditions was performed on January 27, 2015. The weather was sunny and wet; the temperature was approximately 55 degrees. A visual reconnaissance was performed utilizing information obtained from the City of Renton GIS Mapping. Please refer to storm drainage mapping exhibits that follow for a depiction of the downstream drainage conditions. Upstream: A detention vault constructed for the Marvin Garden Townhomes project is located east of the Skattum properties and presently discharges to a ditch east located near the northeast property corner. Drainage from this system will be collected and conveyed along the east and south property lines to bypass the Skattum Plat’s detention vault. Please refer to Figure 3A for the location of the Marvin Garden Townhomes vault. Downstream: The runoff is tributary to the existing ditch to the west of the site. The ditch conveys runoff to the south for approximately 320 feet before crossing SE 172nd Street via an existing closed pipe conveyance system for 68 feet. Runoff then appears to sheet flow down the hill to an existing ditch along the north side of Benson Drive South before entering an existing closed pipe conveyance system. The conveyance system directs runoff to the west for 80 feet where runoff then enters a ditch and continues west for approximately 400 feet. Runoff is then directed to the southwest for approximately 580 feet via a closed pipe system within South 36th Street. The field reconnaissance was terminated as the investigation exceeded the required ¼ mile point analysis. Downstream Concerns & Effects of Proposed Project: Discharge from the developed site will sheet flow across the property in a similar fashion as it presently exists. The downstream drainage system consists of a series of catch basins, ditches, and closed pipe systems. No adverse impacts to the downstream system are anticipated or expected. 5 Figure 3A – Downstream Mapping (City of Renton GIS) Figure 3B – Downstream Mapping (City of Renton GIS) Marvin Gardens Townhomes vault SITE Match Line Match Line 6 SECTION 4: Flow Control and water quality Facility Analysis and Design A formal flow control facility is required for the project site based on Section 1.2.3 of the City of Renton Surface Water Design Manual (SWDM). According to the Flow Control Application Map in the City of Renton SWDM the project site is located within the Flow Control Duration Standard (Forested Conditions). This flow control standard is equivalent to the Conservation Flow Control Area in the King County SWDM which utilizes historic site conditions for the predeveloped flow rates. A combined detention and wetvault is proposed to meet the Flow Control and Water Quality Requirements. Flow control BMPS will be analyzed and sized in the preparation of the Engineering Drawings. A hydrologic analysis of the site was completed in order to size the required on site detention and water quality treatment necessary to account for the increase in the peak storm water release rate for the developed site. The site was analyzed for the pre-developed and developed conditions under the King County Continuous Runoff Time Series (KCRTS) hydrograph model using the KCRTS software developed and provided by the King County Surface Water Management Division. Below are the historic and developed KCRTS flow rates output. Please refer to Appendix A for the complete KCRTS analysis. Due to topographic constraints a portion of the project area cannot be intercepted therefore an area swap is proposed. The area swap is summarized below (see Developed Conditions Map): Impervious Area Swap Summary (See map below) Project Swap Area = 1,673 SF Off-Site Trade Area = 1,600 SF Historic Site Conditions: 7 Flow Frequency Analysis Time Series File:skattum2ex.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- -----Flow Frequency Analysis------- Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 0.132 2 2/09/01 18:00 0.170 1 100.00 0.990 0.036 7 1/06/02 3:00 0.132 2 25.00 0.960 0.098 4 2/28/03 3:00 0.102 3 10.00 0.900 0.004 8 3/24/04 20:00 0.098 4 5.00 0.800 0.058 6 1/05/05 8:00 0.086 5 3.00 0.667 0.102 3 1/18/06 21:00 0.058 6 2.00 0.500 0.086 5 11/24/06 4:00 0.036 7 1.30 0.231 0.170 1 1/09/08 9:00 0.004 8 1.10 0.091 Computed Peaks 0.157 50.00 0.980 Developed Conditions (without flow control): Flow Frequency Analysis Time Series File:skattum2de.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- -----Flow Frequency Analysis------- Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 0.393 6 2/09/01 2:00 0.794 1 100.00 0.990 0.321 8 1/05/02 16:00 0.506 2 25.00 0.960 0.472 3 2/27/03 7:00 0.472 3 10.00 0.900 0.348 7 8/26/04 2:00 0.419 4 5.00 0.800 0.419 4 10/28/04 16:00 0.417 5 3.00 0.667 0.417 5 1/18/06 16:00 0.393 6 2.00 0.500 0.506 2 10/26/06 0:00 0.348 7 1.30 0.231 0.794 1 1/09/08 6:00 0.321 8 1.10 0.091 Computed Peaks 0.698 50.00 0.980 8 Outlet Riser: The outlet riser for the combined facility was sized per Section 5.3.4.2 of the KCSWDM. A 12- inch diameter riser, with 0.50 feet of head, can convey 2.67 CFS. The 100-Year developed peak flows for the drainage basin tributary to the detention vault is 0.740 CFS. QORIFICE = C x A x (2 x g x H)1/2 where: D = diameter (ft) – 1.0’ H = head (ft) – 0.50' Existing Conditions Map 9 Developed Conditions Map 10 Water Quality: The proposed pollution generating impervious surfaces are greater than the 5,000 SF threshold, therefore water quality treatment is required for this project. The area-specific water quality treatment was determined to be Basic. The project proposes a combined detention and wetvault system to meet the water quality requirement. The storm water facility incorporates and provides a two-cell basic wet vault (i.e. VB/VR = 3.0) into the design of the storm water control and treatment facility by providing additional storage volume below the detention vault volume. The wet vault was designed as detailed in the 2009 KCSWDM utilizing the following equation: Vb = fVr = f (0.90Ai + 0.25At) x (R/12)} where; Vb = wetpool volume (cu. ft.) f = volume factor = 3.0 Vr = volume of runoff from the mean annual storm (cu. ft.) Ai = area of impervious surface (sf) At = area of till soil covered with grass or forest (sf) R/12 = rainfall from mean annual storm (feet) = 0.47/12 Impervious Areas (Ai) = 58,370 sf Pervious Areas (Ao) = 33,106 sf Vb = 3.0Vr = 3.0(0.90 x Ai + 0.25 x At ) x (0.47/12) = 7,145 c.f. (required volume) The proposed vault provides 28,000 CF of live storage and 7,200 CF of dead storage. SECTION 5: Conveyance System Analysis and Design The on-site drainage conveyance system is planned to be constructed of a series of catch basins interconnected with 12” PVC pipe. The conveyance calculations were performed using Manning’s Equation. The conveyance system was checked to ensure that during the 100-year storm event, the system would function adequately. The 100-year peak flow using KCRTS 15-minute time steps from the developed site was compared to the maximum capacity of the pipe. Using the Manning’s Equation, the maximum capacity of a 12” pipe sloped at 0.50% is 2.98 cfs, which is greater than the actual 100-year flow of 1.83 cfs (see output below). Since all pipes within the proposed conveyance system are sloped at grades equal to or steeper than 0.50%, the system will have adequate capacity to convey the generated runoff. 11 Flow Frequency Analysis Time Series File:skatt2conv.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- -----Flow Frequency Analysis------- Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 0.601 6 8/27/01 18:00 1.83 1 100.00 0.990 0.425 8 1/05/02 15:00 1.29 2 25.00 0.960 1.29 2 12/08/02 17:15 0.837 3 10.00 0.900 0.484 7 8/23/04 14:30 0.727 4 5.00 0.800 0.727 4 11/17/04 5:00 0.716 5 3.00 0.667 0.716 5 10/27/05 10:45 0.601 6 2.00 0.500 0.837 3 10/25/06 22:45 0.484 7 1.30 0.231 1.83 1 1/09/08 6:30 0.425 8 1.10 0.091 Computed Peaks 1.65 50.00 0.980 12 SECTION 6: Special Reports and Studies  Geotechnical Engineering Study; Earth Solutions NW; December 20, 2016  Arborist Report; American Forest Management; December 13, 2016  Wetland & Stream Reconnaissance; Altmann Oliver Associates; May 21, 2016 SECTION 7: Other Permits Single-Family Residential Building Permits and a Right-of-Way Use Permit from the City of Renton will be required. Utility permits to construct the water and sewer system will be required from Soos Creek Water and Sewer Distict. SECTION 8: CSWPP Analysis and Design Several standard Best Management Practices (BMPs) will be utilized by the contractor to minimize the amount of erosion and sedimentation that may be perpetuated by the construction site. Some of the measures might include filter fence, catch basin protection, and standard ground cover practices. A general stormwater permit will be required from the Washington Department of Ecology and will be obtained prior to construction. SECTION 9: Bond Quantities, Facility Summaries, and Declaration of Covenant These documents will be provided at the time of Single-Family Building Permit application. SECTION 10: Operations and Maintenance Manual A draft Operations & Maintenance Manual is provided in Appendix B. APPENDIX A KCRTS HYDROLOGIC ANALYSES Retention/Detention Facility Type of Facility: Detention Vault Facility Length: 80.00 ft Facility Width: 50.00 ft Facility Area: 4000. sq. ft Effective Storage Depth: 7.00 ft Stage 0 Elevation: 0.00 ft Storage Volume: 28000. cu. ft Riser Head: 7.00 ft Riser Diameter: 12.00 inches Number of orifices: 3 Full Head Pipe Orifice # Height Diameter Discharge Diameter (ft) (in) (CFS) (in) 1 0.00 0.69 0.034 2 4.70 1.25 0.064 4.0 3 6.00 1.00 0.027 4.0 Top Notch Weir: None Outflow Rating Curve: None Stage Elevation Storage Discharge Percolation (ft) (ft) (cu. ft) (ac-ft) (cfs) (cfs) 0.00 0.00 0. 0.000 0.000 0.00 0.01 0.01 40. 0.001 0.002 0.00 0.02 0.02 80. 0.002 0.002 0.00 0.03 0.03 120. 0.003 0.002 0.00 0.04 0.04 160. 0.004 0.003 0.00 0.05 0.05 200. 0.005 0.003 0.00 0.06 0.06 240. 0.006 0.003 0.00 0.20 0.20 800. 0.018 0.006 0.00 0.34 0.34 1360. 0.031 0.007 0.00 0.48 0.48 1920. 0.044 0.009 0.00 0.61 0.61 2440. 0.056 0.010 0.00 0.75 0.75 3000. 0.069 0.011 0.00 0.89 0.89 3560. 0.082 0.012 0.00 1.03 1.03 4120. 0.095 0.013 0.00 1.16 1.16 4640. 0.107 0.014 0.00 1.30 1.30 5200. 0.119 0.015 0.00 1.44 1.44 5760. 0.132 0.015 0.00 1.57 1.57 6280. 0.144 0.016 0.00 1.71 1.71 6840. 0.157 0.017 0.00 1.85 1.85 7400. 0.170 0.017 0.00 1.99 1.99 7960. 0.183 0.018 0.00 2.12 2.12 8480. 0.195 0.019 0.00 2.26 2.26 9040. 0.208 0.019 0.00 2.40 2.40 9600. 0.220 0.020 0.00 2.54 2.54 10160. 0.233 0.020 0.00 2.67 2.67 10680. 0.245 0.021 0.00 2.81 2.81 11240. 0.258 0.021 0.00 2.95 2.95 11800. 0.271 0.022 0.00 3.08 3.08 12320. 0.283 0.023 0.00 3.22 3.22 12880. 0.296 0.023 0.00 3.36 3.36 13440. 0.309 0.023 0.00 3.50 3.50 14000. 0.321 0.024 0.00 3.63 3.63 14520. 0.333 0.024 0.00 3.77 3.77 15080. 0.346 0.025 0.00 3.91 3.91 15640. 0.359 0.025 0.00 4.04 4.04 16160. 0.371 0.026 0.00 4.18 4.18 16720. 0.384 0.026 0.00 4.32 4.32 17280. 0.397 0.027 0.00 4.46 4.46 17840. 0.410 0.027 0.00 4.59 4.59 18360. 0.421 0.027 0.00 4.70 4.70 18800. 0.432 0.028 0.00 4.71 4.71 18840. 0.433 0.028 0.00 4.73 4.73 18920. 0.434 0.029 0.00 4.74 4.74 18960. 0.435 0.031 0.00 4.75 4.75 19000. 0.436 0.033 0.00 4.77 4.77 19080. 0.438 0.036 0.00 4.78 4.78 19120. 0.439 0.040 0.00 4.79 4.79 19160. 0.440 0.041 0.00 4.80 4.80 19200. 0.441 0.042 0.00 4.94 4.94 19760. 0.454 0.049 0.00 5.08 5.08 20320. 0.466 0.055 0.00 5.22 5.22 20880. 0.479 0.060 0.00 5.35 5.35 21400. 0.491 0.064 0.00 5.49 5.49 21960. 0.504 0.068 0.00 5.63 5.63 22520. 0.517 0.071 0.00 5.76 5.76 23040. 0.529 0.075 0.00 5.90 5.90 23600. 0.542 0.078 0.00 6.00 6.00 24000. 0.551 0.080 0.00 6.01 6.01 24040. 0.552 0.080 0.00 6.02 6.02 24080. 0.553 0.081 0.00 6.03 6.03 24120. 0.554 0.082 0.00 6.04 6.04 24160. 0.555 0.084 0.00 6.05 6.05 24200. 0.556 0.086 0.00 6.06 6.06 24240. 0.556 0.088 0.00 6.07 6.07 24280. 0.557 0.089 0.00 6.08 6.08 24320. 0.558 0.089 0.00 6.09 6.09 24360. 0.559 0.090 0.00 6.23 6.23 24920. 0.572 0.097 0.00 6.37 6.37 25480. 0.585 0.104 0.00 6.51 6.51 26040. 0.598 0.109 0.00 6.64 6.64 26560. 0.610 0.114 0.00 6.78 6.78 27120. 0.623 0.118 0.00 6.92 6.92 27680. 0.635 0.123 0.00 7.00 7.00 28000. 0.643 0.125 0.00 7.10 7.10 28400. 0.652 0.436 0.00 7.20 7.20 28800. 0.661 1.000 0.00 7.30 7.30 29200. 0.670 1.730 0.00 7.40 7.40 29600. 0.680 2.530 0.00 7.50 7.50 30000. 0.689 2.810 0.00 7.60 7.60 30400. 0.698 3.070 0.00 7.70 7.70 30800. 0.707 3.310 0.00 7.80 7.80 31200. 0.716 3.530 0.00 7.90 7.90 31600. 0.725 3.740 0.00 8.00 8.00 32000. 0.735 3.930 0.00 8.10 8.10 32400. 0.744 4.120 0.00 8.20 8.20 32800. 0.753 4.300 0.00 8.30 8.30 33200. 0.762 4.470 0.00 8.40 8.40 33600. 0.771 4.640 0.00 8.50 8.50 34000. 0.781 4.790 0.00 8.60 8.60 34400. 0.790 4.950 0.00 8.70 8.70 34800. 0.799 5.100 0.00 8.80 8.80 35200. 0.808 5.240 0.00 Hyd Inflow Outflow Peak Storage Target Calc Stage Elev (Cu-Ft) (Ac-Ft) 1 0.79 0.17 0.42 7.09 7.09 28378. 0.651 2 0.39 ******* 0.12 6.73 6.73 26936. 0.618 3 0.47 ******* 0.10 6.29 6.29 25159. 0.578 4 0.40 ******* 0.08 5.91 5.91 23636. 0.543 5 0.42 ******* 0.04 4.80 4.80 19184. 0.440 6 0.25 ******* 0.03 4.32 4.32 17275. 0.397 7 0.32 ******* 0.03 4.16 4.16 16645. 0.382 8 0.35 ******* 0.02 2.64 2.64 10548. 0.242 ---------------------------------- Route Time Series through Facility Inflow Time Series File:skattum2de.tsf Outflow Time Series File:rdout Inflow/Outflow Analysis Peak Inflow Discharge: 0.794 CFS at 6:00 on Jan 9 in Year 8 Peak Outflow Discharge: 0.419 CFS at 10:00 on Jan 9 in Year 8 Peak Reservoir Stage: 7.09 Ft Peak Reservoir Elev: 7.09 Ft Peak Reservoir Storage: 28378. Cu-Ft : 0.651 Ac-Ft Flow Duration from Time Series File:rdout.tsf Cutoff Count Frequency CDF Exceedence_Probability CFS % % % 0.002 27075 44.154 44.154 55.846 0.558E+00 0.005 8578 13.989 58.143 41.857 0.419E+00 0.009 6853 11.176 69.318 30.682 0.307E+00 0.012 6421 10.471 79.790 20.210 0.202E+00 0.016 4863 7.931 87.720 12.280 0.123E+00 0.019 3217 5.246 92.966 7.034 0.703E-01 0.023 1722 2.808 95.775 4.225 0.423E-01 0.026 1789 2.917 98.692 1.308 0.131E-01 0.030 462 0.753 99.446 0.554 0.554E-02 0.033 13 0.021 99.467 0.533 0.533E-02 0.037 20 0.033 99.499 0.501 0.501E-02 0.040 5 0.008 99.507 0.492 0.492E-02 0.044 37 0.060 99.568 0.432 0.432E-02 0.047 35 0.057 99.625 0.375 0.375E-02 0.050 34 0.055 99.680 0.320 0.320E-02 0.054 28 0.046 99.726 0.274 0.274E-02 0.057 26 0.042 99.768 0.232 0.232E-02 0.061 16 0.026 99.795 0.205 0.205E-02 0.064 11 0.018 99.812 0.188 0.188E-02 0.068 12 0.020 99.832 0.168 0.168E-02 0.071 15 0.024 99.856 0.144 0.144E-02 0.075 18 0.029 99.886 0.114 0.114E-02 0.078 18 0.029 99.915 0.085 0.848E-03 0.082 6 0.010 99.925 0.075 0.750E-03 0.085 1 0.002 99.927 0.073 0.734E-03 0.089 2 0.003 99.930 0.070 0.701E-03 0.092 7 0.011 99.941 0.059 0.587E-03 0.096 5 0.008 99.949 0.051 0.506E-03 0.099 7 0.011 99.961 0.039 0.391E-03 0.103 6 0.010 99.971 0.029 0.294E-03 0.106 2 0.003 99.974 0.026 0.261E-03 0.109 2 0.003 99.977 0.023 0.228E-03 0.113 3 0.005 99.982 0.018 0.179E-03 0.116 3 0.005 99.987 0.013 0.130E-03 0.120 3 0.005 99.992 0.008 0.815E-04 0.123 3 0.005 99.997 0.003 0.326E-04 Duration Comparison Anaylsis Base File: skattum2ex.tsf New File: rdout.tsf Cutoff Units: Discharge in CFS -----Fraction of Time----- ---------Check of Tolerance------- Cutoff Base New %Change Probability Base New %Change 0.029 | 0.95E-02 0.57E-02 -40.5 | 0.95E-02 0.029 0.027 -6.5 0.037 | 0.63E-02 0.50E-02 -20.5 | 0.63E-02 0.037 0.028 -24.3 0.045 | 0.50E-02 0.41E-02 -18.0 | 0.50E-02 0.045 0.039 -13.9 0.053 | 0.37E-02 0.29E-02 -21.8 | 0.37E-02 0.053 0.047 -10.7 0.061 | 0.29E-02 0.21E-02 -28.4 | 0.29E-02 0.061 0.053 -12.5 0.069 | 0.22E-02 0.16E-02 -26.5 | 0.22E-02 0.069 0.059 -14.6 0.077 | 0.15E-02 0.10E-02 -30.4 | 0.15E-02 0.077 0.070 -8.6 0.085 | 0.10E-02 0.73E-03 -27.4 | 0.10E-02 0.085 0.077 -9.2 0.093 | 0.62E-03 0.57E-03 -7.9 | 0.62E-03 0.093 0.092 -0.8 0.100 | 0.34E-03 0.31E-03 -9.5 | 0.34E-03 0.100 0.099 -1.0 0.108 | 0.21E-03 0.23E-03 7.7 | 0.21E-03 0.108 0.112 3.2 0.116 | 0.16E-03 0.13E-03 -20.0 | 0.16E-03 0.116 0.115 -0.9 0.124 | 0.98E-04 0.00E+00 -100.0 | 0.98E-04 0.124 0.120 -3.8 0.132 | 0.16E-04 0.00E+00 -100.0 | 0.16E-04 0.132 0.124 -6.2 Maximum positive excursion = 0.004 cfs ( 3.4%) occurring at 0.108 cfs on the Base Data:skattum2ex.tsf and at 0.112 cfs on the New Data:rdout.tsf Maximum negative excursion = 0.012 cfs (-29.1%) occurring at 0.040 cfs on the Base Data:skattum2ex.tsf and at 0.029 cfs on the New Data:rdout.tsf APPENDIX B MAINTENANCE and OPERATIONS MANUAL APPENDIX C GEOTECHNICAL REPORT EarthSolutionsNWLLC EarthSolutionsNWLLC Geotechnical Engineering Geology Environmental Scientists Construction Monitoring 1805 -136th Place N.E.,Suite 201 Bellevue,WA 98005 (425)449-4704 Fax (425)449-4711 www.earthsolutionsnw.com GEOTECHNICAL ENGINEERING STUDY PROPOSED RESIDENTIAL SHORT PLAT 17018 &17022 -106th AVENUE SOUTHEAST RENTON,WASHINGTON ES-4948 Drwn. Checked Date Date Proj.No. Plate Earth Solutions NWLLC Geotechnical Engineering,Construction Monitoring EarthSolutionsNWLLC EarthSolutionsNWLLC and Environmental Sciences Vicinity Map Skattum Short Plat Renton,Washington MRS BJP 12/19/2016 Dec.2016 4948 1 NOTE:This plate may contain areas of color.ESNW cannot be responsible for any subsequent misinterpretation of the information resulting from black &white reproductions of this plate. Reference: King County,Washington Map 656 By The Thomas Guide Rand McNally 32nd Edition SITE Drwn. Checked Date Date Proj.No. Plate Earth Solutions NWLLC Geotechnical Engineering,Construction Monitoring EarthSolutionsNWLLC EarthSolutionsNWLLC and Environmental Sciences Test Pit Location Plan Skattum Short Plat Renton,Washington MRS BJP 12/19/2016 Dec.2016 4948 2 NOTE:This plate may contain areas of color.ESNW cannot be responsible for any subsequent misinterpretation of the information resulting from black &white reproductions of this plate. NOTE:The graphics shown on this plate are not intended for design purposes or precise scale measurements,but only to illustrate the approximate test locations relative to the approximate locations of existing and /or proposed site features.The information illustrated is largely based on data provided by the client at the time of our study.ESNW cannot be responsible for subsequent design changes or interpretation of the data by others. 0 30 60 12 0 Scale in Feet1"=60' NORTHLEGEND Approximate Location of ESNW Test Pit,Proj.No. ES-4948,Dec.2016 Subject Site Existing Building Proposed Building TP-1 Storm Drainage TP-1 TP-2 TP-3 TP-4TP-5 106TH AVENUE S.E.390 400 390 400 Drwn. Checked Date Date Proj.No. Plate Earth Solutions NWLLC Geotechnical Engineering,Construction MonitoringandEnvironmentalSciences EarthSolutionsNWLLC EarthSolutionsNWLLC RETAINING WALL DRAINAGE DETAIL Skattum Short Plat Renton,Washington MRS BJP 12/19/2016 Dec.2016 4948 3 NOTES: Free Draining Backfill should consist of soil having less than 5 percent fines. Percent passing #4 should be 25 to 75 percent. Sheet Drain may be feasible in lieu of Free Draining Backfill,per ESNW recommendations. Drain Pipe should consist of perforated, rigid PVC Pipe surrounded with 1" Drain Rock. LEGEND: Free Draining Structural Backfill 1 inch Drain Rock 18"Min. Structural Fill Perforated Drain Pipe (Surround In Drain Rock) SCHEMATIC ONLY -NOT TO SCALE NOT A CONSTRUCTION DRAWING Drwn. Checked Date Date Proj.No. Plate Earth Solutions NWLLC Geotechnical Engineering,Construction Monitoring and Environmental Sciences EarthSolutionsNWLLC EarthSolutionsNWLLC FOOTING DRAIN DETAIL Slope Perforated Rigid Drain Pipe (Surround with 1"Rock) 18"(Min.) NOTES: Do NOT tie roof downspouts to Footing Drain. Surface Seal to consist of 12"of less permeable,suitable soil.Slope away from building. LEGEND: Surface Seal;native soil or other low permeability material. 1"Drain Rock SCHEMATIC ONLY -NOT TO SCALE NOT A CONSTRUCTION DRAWING Skattum Short Plat Renton,Washington MRS BJP 12/19/2016 Dec.2016 4948 4 APPENDIX D ARBORIST REPORT Arborist Report Skattum Plat 17018 & 17022 106th Ave SE Renton, WA December 13th, 2016 American Forest Management 12/13/2016 Table of Contents 1. Introduction .............................................................................................................. 1 2. Description ............................................................................................................... 1 3. Methodology ............................................................................................................ 1 4. Observations ........................................................................................................... 2 5. Discussion ............................................................................................................... 3 6. Tree Retention ......................................................................................................... 3 7. Tree Replacement .................................................................................................. .3 8. Tree Protection Measures…………………………………………………………………4 Appendix Site/Tree Photos – pages 7 - 12 Tree Summary Table – attached Tree Locator Map - attached Tree Plan Map – attached City of Renton Tree Protection Measures – page 6 Skattum Plat - Arborist Report Page 1 American Forest Management 12/13/2016 1. Introduction American Forest Management, Inc. was contacted by Keith Litchfield of Litchfield Engineering and was asked to compile an ‘Arborist Report’ for two parcels located within the City of Renton. The proposed subdivision encompasses the properties at 17018 & 17022 106th Ave SE. Our assignment is to prepare a written report on present tree conditions, which is to be filed with the preliminary permit application. This report encompasses all of the criteria set forth under City of Renton code section 4-4-130. The tree retention requirement is 30% of significant trees. Date of Field Examination: December 6th, 2016 2. Description 70 significant trees were identified and assessed on the property. According to City of Renton code, a significant tree is a tree with a caliper (trunk diameter measured 4-1/2’ above the ground) of at least 6” or an alder or cottonwood tree with a caliper of at least 8”. Trees planted within the most recent 10 years qualify as significant trees, regardless of the actual caliper. A numbered aluminum tag was placed on the lower trunks of the subject trees. These numbers were used for this assessment. Tree tag numbers correspond with the numbers on the Tree Summary Tables and copy of the attached site survey. There are eight neighboring trees with a drip lines that extend over the property line. 3. Methodology Each tree in this report was visited. Tree diameters were measured by tape. The tree heights were measured using a Spiegel Relaskop. Each tree was visually examined for defects and vigor. The tree assessment procedure involves the examination of many factors:  The crown of the tree is examined for current vigor. This is comprised of inspecting the crown (foliage, buds and branches) for color, density, form, and annual shoot growth, limb dieback and disease. The percentage of live crown is estimated for coniferous species only and scored appropriately.  The bole or main stem of the tree is inspected for decay, which includes cavities, wounds, fruiting bodies of decay (conks or mushrooms), seams, insects, bleeding, callus development, broken or dead tops, structural defects and unnatural leans. Structural defects include crooks, forks with V-shaped crotches, multiple attachments, and excessive sweep.  The root collar and roots are inspected for the presence of decay, insects and/or damage, as well as if they have been injured, undermined or exposed, or original grade has been altered. Based on these factors a determination of condition is made. The four condition categories are described below based on the species traits assessed: Excellent – free of structural defects, no disease or pest problems, no root issues, excellent structure/form with uniform crown or canopy, foliage of normal color and density, above average vigor, it will be wind firm if isolated, suitable for its location Good – free of significant structural defects, no disease concerns, minor pest issues, no significant root issues, good structure/form with uniform crown or canopy, foliage of normal color and density, average or normal vigor, will be wind firm if isolated or left as part of a grouping or grove of trees, suitable for its location Skattum Plat - Arborist Report Page 2 American Forest Management 12/13/2016 Fair – minor structural defects not expected to contribute to a failure in near future, no disease concerns, moderate pest issues, no significant root issues, asymmetric or unbalanced crown or canopy, average or normal vigor, foliage of normal color, moderate foliage density, will be wind firm if left as part of a grouping or grove of trees, cannot be isolated, suitable for its location Poor – major structural defects expected to fail in near future, disease or significant pest concerns, decline due to old age, significant root issues, asymmetric or unbalanced crown or canopy, sparse or abnormally small foliage, poor vigor, not suitable for its location A ‘viable’ tree is “A significant tree that a qualified professional has determined to be in good health, with a low risk of failure due to structural defects, is wind firm if isolated or remains as part of a grove, and is a species that is suitable for its location.” Trees considered ‘non-viable’ are trees that are in poor condition due to disease, age related decline, have significant decay issues and/or cumulative structural defects, which exacerbate failure potential. The attached tree map indicates the ‘condition’ of the subject trees found at the site. 4. Observations The subject trees are primarily native, mature conifers. Specific tree information for individual trees can be found on the attached tree table. The Douglas-fir trees on the property are generally healthy and mature, estimated at 60 – 70 years of age. Most were planted in rows or clusters. The row of Douglas-fir trees on the west property line, #150 - #156, are growing very closely together and should not be isolated. One incident of fungal disease was observed. A Phaeolus schweinitzii conk was found 1’ from the trunk of tree #132. The vigor of tree #132 is good and the infection is suspected to be incipient. Foliage color is good. All of the Douglas-fir trees on the site are viable. The western red cedar trees on the property are generally mature. Most of the western red cedar trees on the property are in groupings. Decay was observed in multiple trees. The decay is suspected to be brown cubical rot, but no fungal fruiting bodies were found. Some of the western red cedar trees were topped in the past. Co- dominant trunks with included bark were commonly observed and are the most concerning defect. The western red cedar trees on the property range in condition and all but one are viable. Tree #165 - #167 are black cottonwood trees on the west side of the property. Tree #165 and #166 are mature black cottonwoods growing closely together. Tree #165 has a DBH of 54” and a height of 167’. Tree #166 has a DBH of 45” and a height of 154’. Large limbs on both tree have failed but no other concerning defects were observed. Tree #167 is younger. The top of this tree broke off and there is decay in the trunk. All three trees are viable. Tree #149 is an English oak on the west property line. This tree has a forked trunk. The attachment between the two trunks is good. The crown is full and no other defects were observed. This tree is in good condition and is viable. Tree #125, #130 and #131 are European larch trees on the west side of the property. Tree #130 and #131 have poor trunk taper. All three trees are viable. Neighboring Trees Tree #201 - #206 are mature big leaf maple trees north and east of the property lines. Big leaf maple trees often have large lateral branches. Co-dominant trunks with included bark were the most common defects observed. All six trees are in fair to good condition and are viable. Tree #207 is a mature Douglas-fir south of the property line. This tree has no concerning defects, is in good condition and is viable. Skattum Plat - Arborist Report Page 3 American Forest Management 12/13/2016 5. Discussion The extent of drip-lines (farthest reaching branches) for the subject trees can be found on the tree summary tables at the back of this report. These have also been delineated on a copy of the site survey for viable/healthy trees proposed for retention. The information plotted on the attached survey plan may need to be transferred to a final tree retention/protection plan to meet City submittal requirements. The trees that are to be removed shall be shown “X’d” out on the final plan. The Limits of Disturbance (LOD) measurements can also be found on the tree summary table. This is the recommended distance of the closest impact (soil excavation) to the trunk face. These should be referenced when determining tree retention feasibility. The LOD measurements are based on species, age, condition, drip- line, prior improvements, proposed impacts and the anticipated cumulative impacts to the entire root zone. Tree Protection fencing shall be located beyond the drip-line edge of retained trees, and only moved back to the LOD when work is authorized. Trees on the property growing closely together are recommended for retention as groupings. One example is the row of Douglas-fir trees, #150 - #156 are growing in a row with only a few feet between each trunk. When trees are growing closely together, they often develop small trunk taper and live crown ratios. As long as the trees are retained as groupings and not isolated, the risk of failure is lessened. A Phaeolus schweinitzii conk was found 1’ from the trunk of tree #132. The vigor of tree #132 is good and the infection is suspected to be incipient. All conifers are susceptible to Phaeolus schweinitzii and it is likely present in multiple trees on the property. Trees in advanced stages of the disease often have thin crowns and/or branch dieback, and swollen lower trunks. No trees with advanced or significant internal decay were identified. The western red cedar trees on the property are mature and some concerning defects were observed. Brown cubical rot is suspected to be in multiple western red cedar trees on the property. The development of internal decay columns within mature cedar is common. As long as trees are vigorous and actively growing, the risk of failure remains low. Western red cedars are good at compartmentalizing decay radially and the presence of rot is not necessarily an indication that the tree is declining. The largest concern with the western red cedar trees on the site is co-dominant stems with included bark. Tree #115 is a western red cedar with co-dominant stems that have split apart. Failure of this tree is extremely likely. Tree #115 is a high risk tree and should be removed before work commences on the site. The tree density on the site is currently low and mainly concentrated in the southwest region of the property. Most of the trees are in the center and west side of the property. Sidewalk improvements, water utilites and the construction of new homes will prevent retention of the majority of the existing trees. The site will fall 8% short of meeting the required 30% significant tree retention requirement. New trees will be planted to mitigate for the tree removal and to enhance the landscape. There are no concerns with neighboring trees. The tree protection measures below will serve to protect these trees. 6. Tree Retention A total of 70 significant trees were identified on the subject property. One of the significant trees is in poor condition. This tree was not included in the tree calculation. Landmark trees and tree groves were prioritized when selecting trees for retention, per the City of Renton tree code 4-4-130. Tree Calculation based on 69, healthy, viable, significant trees Viable Trees proposed for removal – 54 (78%) Viable Trees proposed for retention – 15 (22%) Skattum Plat - Arborist Report Page 4 American Forest Management 12/13/2016 7. Tree Replacement Replacements trees may be required. Consult your city planner for tree replacement requirements. All replacement trees are to be planted on site. For planting and maintenance specifications, refer to Section 4-4- 130 of the Renton Tree Ordinances. 8. Tree Protection Measures The following guidelines are recommended to ensure that the designated space set aside for the preserved trees are protected and construction impacts are kept to a minimum. Refer to the City of Renton Code 4-4-130- 9. Protection Measures During Construction for more information.  Tree protection barriers shall be initially erected at 5’ outside of the drip-line prior to moving any heavy equipment on site.  Tree protection fencing shall only be moved where necessary to install improvements, but only as close as the Limits of Disturbance, as indicated on the attached plan.  Excavation limits should be laid out in paint on the ground to avoid over excavating.  Excavations within the drip-lines shall be monitored by a qualified tree professional so necessary precautions can be taken to decrease impacts to tree parts. A qualified tree professional shall monitor excavations when work is required and allowed up to the “Limits of Disturbance”.  To establish sub grade for foundations, curbs and pavement sections near the trees, soil should be removed parallel to the roots and not at 90 degree angles to avoid breaking and tearing roots that lead back to the trunk within the drip-line. Any roots damaged during these excavations should be exposed to sound tissue and cut cleanly with a saw. Cutting tools should be sterilized with alcohol.  Areas excavated within the drip-line of retained trees should be thoroughly irrigated weekly during dry periods.  Preparations for final landscaping shall be accomplished by hand within the drip-lines of retained trees. Plantings within the drip lines shall be limited. Large equipment shall be kept outside of the tree protection zones. Tree Type Removal Retained Total Landmark # 11 0 11 Landmark % 100% 0% 100% Significant # 43 15 58 Significant % 74% 26% 100% Total # 54 15 69 Total % 78% 22% 100% Skattum Plat - Arborist Report Page 5 American Forest Management 12/13/2016 There is no warranty suggested for any of the trees subject to this report. Weather, latent tree conditions, and future man-caused activities could cause physiologic changes and deteriorating tree condition. Over time, deteriorating tree conditions may appear and there may be conditions, which are not now visible which, could cause tree failure. This report or the verbal comments made at the site in no way warrant the structural stability or long term condition of any tree, but represent my opinion based on the observations made. Nearly all trees in any condition standing within reach of improvements or human use areas represent hazards that could lead to damage or injury. Please call if you have any questions or I can be of further assistance. Sincerely, Kelly Wilkinson kelly.wilkinson@afmforest.com ISA Certified Arborist #PN-7673A ISA Tree Risk Assessment Qualified Skattum Plat - Arborist Report Page 6 American Forest Management 12/13/2016 City of Renton Code 4-4-130- 9. Protection Measures During Construction a. Construction Storage Prohibited: The applicant may not fill, excavate, stack or store any equipment, dispose of any materials, supplies or fluids, operate any equipment, install impervious surfaces, or compact the earth in any way within the area defined by the drip line of any tree to be retained. b. Fenced Protection Area Required: Prior to development activities, the applicant shall erect and maintain six-foot (6') high chain link temporary construction fencing around the drip lines of all retained trees or at a distance surrounding the tree equal to one and one-quarter feet (1.25') for every one inch (1") of trunk caliper, whichever is greater, or along the perimeter of a tree protection tract. Placards shall be placed on fencing every fifty feet (50') indicating the words, “NO TRESPASSING – Protected Trees,” or on each side of the fencing if less than fifty feet (50'). Site access to individually protected trees or groups of trees shall be fenced and signed. Individual trees shall be fenced on four (4) sides. In addition, the applicant shall provide supervision whenever equipment or trucks are moving near trees. c. Protection from Grade Changes: If the grade level adjoining to a tree to be retained is to be raised, the applicant shall construct a dry rock wall or rock well around the tree. The diameter of this wall or well must be equal to the tree’s drip line. d. Impervious Surfaces Prohibited within the Drip Line: The applicant may not install impervious surface material within the area defined by the drip line of any tree to be retained. e. Restrictions on Grading within the Drip Lines of Retained Trees: The grade level around any tree to be retained may not be lowered within the greater of the following areas: (i) the area defined by the drip line of the tree, or (ii) an area around the tree equal to one and one-half feet (1-1/2') in diameter for each one inch (1") of tree caliper. A larger tree protection zone based on tree size, species, soil, or other conditions may be required. (Ord. 5676, 12-3-2012) f. Mulch Layer Required: All areas within the required fencing shall be covered completely and evenly with a minimum of three inches (3") of bark mulch prior to installation of the protective fencing. Exceptions may be approved if the mulch will adversely affect protected ground cover plants. (Ord. 5676, 12-3-2012) g. Monitoring Required during Construction: The applicant shall retain a certified arborist or licensed landscape architect to ensure trees are protected from development activities and/or to prune branches and roots, fertilize, and water as appropriate for any trees and ground cover that are to be retained. h. Alternative Protection: Alternative safeguards may be used if determined to provide equal or greater tree protection. (Ord. 5676, 12-3-2012) Skattum Plat - Arborist Report Page 7 American Forest Management 12/13/2016 Photos Northeast corner of the subject property Cluster of western red cedar trees (#106 - #108) Skattum Plat - Arborist Report Page 8 American Forest Management 12/13/2016 Tree #103 and #102 – big leaf maple and Douglas-fir trees Tree #114 – western red cedar with a self-corrected lean and column of trunk decay Skattum Plat - Arborist Report Page 9 American Forest Management 12/13/2016 Tree #113 – western red cedar with column of decay Grouping of western red cedar trees (#109 - #114) Skattum Plat - Arborist Report Page 10 American Forest Management 12/13/2016 Tree #115 – western red cedar with forked trunk and severe decay West side of subject property Skattum Plat - Arborist Report Page 11 American Forest Management 12/13/2016 Tree #132 – Douglas-fir tree with Phaeolus schweinitzii conk Tree #133 – European white birch with a large burl Skattum Plat - Arborist Report Page 12 American Forest Management 12/13/2016 East side of subject property, tree #169 in the center Tree #167 – black cottonwood with poor form Tree Summary Table American Forest Management, Inc. For:Skattum Plat Date:12/7/2016 City of Renton Inspector:Wilkinson Tree/DBH Height Tag #Species (inches)(feet)Condition Viability Comments Proposal N S E W 101 Douglas-fir 22 96 13 / 10 17 / 10 good viable retain 102 Douglas-fir 28 103 14 / 12 11 / 12 16 / 12 8 / 12 good viable Slight lean E retain 103 big leaf maple 29 85 12 / 12 21 / 12 19 / 12 18 / 12 good viable retain 104 Douglas-fir 12 42 9 / 6 14 / 6 17 / 6 fair viable retain 105 western red cedar 20 81 13 10 17 4 good viable remove 106 western red cedar 28 52 4 17 16 6 fair viable Topped remove 107 western red cedar 24 78 10 8 4 6 good viable remove 108 western red cedar 34 72 18 21 11 23 good viable landmark tree remove 109 western red cedar 37 45 10 17 15 10 good viable landmark tree remove 110 western red cedar 32 103 17 9 12 11 fair viable Top broke off, landmark tree remove 111 western red cedar 20 76 4 13 6 6 good viable remove 112 western red cedar 28, 24 (37)96 17 19 8 9 fair viable Forks at 2', landmark tree remove 113 western red cedar 25 77 18 6 5 17 fair viable Decay remove 114 western red cedar 32 68 2 17 7 14 fair viable decay, forked top, slight lean S, landmark tree remove 115 western red cedar 24 46 poor non-viable Trunk splitting, hazardous - non-significant remove 116 western red cedar 28 79 16 10 20 fair viable Connected at base to tree 115 remove 117 western red cedar 33 89 17 / 16 17 / 16 14 / 16 16 / 16 good viable Trunk forks at ~30', some included bark, landmark tree remove 118 Douglas-fir 27 109 8 / 13 10 / 13 12 / 13 9 / 13 good viable flat trunk on north side retain 119 Douglas-fir 26 120 4 / 12 15 / 12 9 / 12 4 / 12 good viable retain 120 Douglas-fir 21 91 12 / 10 9 / 10 16 / 10 good viable retain 121 Douglas-fir 16 81 5 / 8 9 / 8 12 / 8 6 / 8 fair viable retain 122 Douglas-fir 31 118 9 18 6 16 good viable landmark tree remove 123 Douglas-fir 28 111 13 8 9 11 good viable some old lower trunk bleeding remove 124 Douglas-fir 29 118 7 / 12 11 / 12 11 / 12 good viable retain 125 European larch 10 30 10 9 2 9 fair viable remove 126 Douglas-fir 38 110 20 25 24 18 good viable landmark tree remove 127 western red cedar 35 78 19 18 21 good viable landmark tree, in 106th Ave SE right-of-way remove 128 quaking aspen 11 55 9 6 5 11 good viable remove 129 quaking aspen 7 27 0 11 8 2 fair viable remove 130 European larch 14 76 10 6 7 9 fair viable poor trunk taper remove 131 European larch 15 74 6 8 6 11 fair viable poor trunk taper remove Drip-Line/Limits of Disturbance (feet) Tree Summary Table American Forest Management, Inc. For:Skattum Plat Date:12/7/2016 City of Renton Inspector:Wilkinson Tree/DBH Height Tag #Species (inches)(feet)Condition Viability Comments Proposal N S E W Drip-Line/Limits of Disturbance (feet) 132 Douglas-fir 20 74 10 13 6 15 fair viable Phaeolus schweinitzii conk found 1' from trunk on east side remove 133 European white birch 16 64 13 12 7 16 fair viable Burl on trunk remove 134 grand fir 28 77 12 16 14 15 good viable Forked top remove 135 western red cedar 26 84 15 12 19 12 fair viable Forked trunk, minor included bark remove 136 Douglas-fir 13 81 7 10 9 5 good viable remove 137 Douglas-fir 25 115 11 10 8 12 good viable remove 138 Douglas-fir 16 95 10 7 6 12 good viable remove 139 Douglas-fir 24 111 11 17 12 23 good viable remove 140 Douglas-fir 16 100 3 7 6 10 good viable remove 141 Douglas-fir 17 98 11 10 6 12 good viable remove 142 Douglas-fir 22 109 11 14 8 10 good viable remove 143 Douglas-fir 28 110 8 / 13 18 / 13 6 / 13 14 / 13 good viable remove 144 Douglas-fir 33 101 15 / 15 16 / 15 18 / 15 8 / 15 good viable landmark tree remove 145 western red cedar 22 83 6 / 12 12 / 12 16 / 12 5 / 12 good viable in grouping with tree #146 remove 146 western red cedar 27 85 8 / 14 11 / 14 9 / 14 11 / 14 good viable in grouping with tree #145 remove 147 Douglas-fir 29 118 15 8 11 13 good viable remove 148 Douglas-fir 19 100 7 7 9 14 good viable remove 149 English oak 25 91 4 19 11 17 good viable Forked trunk remove 150 Douglas-fir 17 45 13 11 17 good viable remove 151 Douglas-fir 20 95 10 11 good viable Slight lean N remove 152 Douglas-fir 19 91 16 15 good viable remove 153 Douglas-fir 11 63 11 8 good viable remove 154 Douglas-fir 18 85 12 14 good viable remove 155 Douglas-fir 19 83 6 14 good viable remove 156 Douglas-fir 12 52 8 7 7 good viable remove 157 western red cedar 23 38 15 12 11 good viable remove 158 western red cedar 13 23 10 9 9 good viable remove 159 western red cedar 18 39 14 / 15 7 / 15 12 / 15 fair viable Topped retain 160 western red cedar 14 45 13 / 12 9 / 12 7 / 12 fair viable Topped retain 161 western red cedar 19 55 12 / 10 9 / 10 10 / 10 good viable retain 162 western red cedar 23 61 12 / 16 10 / 16 6 / 16 good viable retain 163 Willow 6, 5, 4 (9)39 14 / 6 13 / 6 9 / 6 fair viable retain 164 Douglas-fir 12 51 14 / 6 15 / 6 good viable retain Tree Summary Table American Forest Management, Inc. For:Skattum Plat Date:12/7/2016 City of Renton Inspector:Wilkinson Tree/DBH Height Tag #Species (inches)(feet)Condition Viability Comments Proposal N S E W Drip-Line/Limits of Disturbance (feet) 165 black cottonwood 54 167 18 15 19 fair viable landmark tree remove 166 black cottonwood 45 154 18 17 11 fair viable Large limbs have failed, landmark tree remove 167 black cottonwood 12, 13 (17)55 17 19 16 17 fair viable decay, top broke off remove 168 western red cedar 23 54 16 13 14 14 good viable remove 169 Douglas-fir 23 94 10 17 15 15 good viable remove 170 western red cedar 25 85 8 9 11 11 good viable remove 201 big leaf maple 8, 7 (11)54 6 / 0 good viable Leans W, 10' east of property line protect 202 big leaf maple 16 71 6 / 2 fair viable protect 203 big leaf maple 18, 13, 15 (27)78 9 / 5 fair viable protect 204 big leaf maple 16, 18, 13 (27)70 12 / 14 fair viable 5' from property line protect 205 big leaf maple 29, 32 (43)111 5 / 14 16 / 14 19 / 14 good viable Trunk forks at base, good attachment, landmark tree protect 206 big leaf maple 28 73 18 / 12 good viable protect 207 Douglas-fir 28 94 10 / 2 good viable 8' S of property line protect 208 western red cedar 29, 16 (33)49 8 / 5 good viable 10' S of property line, landmark tree protect Drip-Line and Limits of Disturbance measurements from face of trunk Trees on neighboring properties - Drip-line and Limits of Disturbance measurements from property lines Calculated DBH: the DBH is parenthesis is the square root of the sum of the dbh for each individual stem squared (example with 3 stems: dbh = square root [(stem1)2 +(stem2)2 +(stem3)2]. Neighboring Trees APPENDIX E WETLAND and STREAM RECONASSIANCE May 21, 2016 AOA-5175 Stein Skattum skattum@comcast.net SUBJECT: Wetland and Stream Reconnaissance for: 17018 and 17022 - 106th Ave. SE, Renton, WA Parcels 008700-0265 and -0270 Dear Stein: On May 19, 2016 I conducted a wetland and stream reconnaissance on the subject property utilizing the methodology outlined in the May 2010 Regional Supplement to the Corps of Engineers Wetland Delineation Manual: Western Mountains, Valleys, and Coast Region (Version 2.0). No wetlands or streams are mapped on the City of Renton mapping and no wetlands or streams were identified on or adjacent to the property during the field investigation. Each of the two parcels are currently developed with a single-family residence and associated lawn and maintained yard areas. Scattered trees including Douglas fir (Pseudotsuga menziesii), big-leaf maple (Acer macrophyllum), western red cedar (Thuja plicata), and black cottonwood (Populus trichocarpa) were observed throughout both lots. An upland forested area is located off-site to the east. This off-site area was dominated by big-leaf maple, Indian plum (Oemleria cerasiformis), vine maple (Acer circinatum), bracken fern (Pteridium aquilinum), trailing blackberry (Rubus ursinus), and sword fern (Polystichum munitum). No hydrophytic plant communities were observed on or adjacent to the property. Borings taken throughout the two parcels revealed high chroma, dry, non-hydric, soils and there was no evidence of ponding or prolonged soil saturation anywhere on the property. Stein Skattum May 21, 2016 Page 2 Ditch During the field investigation, a small (~1-foot wide) ditch was observed along the east and south property lines of the site (Figure 1). Stormwater runoff from an off- site development to the northeast is collected in a vault and the overflow is discharged from a pipe at the NE corner of the 17018 residence. Intermittent runoff within the ditch then drains south and west before entering the roadside ditch adjacent the east side of 106th Ave. SE. A slight flow was observed discharging from the off-site vault at the time of the site visit. This runoff was observed infiltrating within the ditch near the southeast corner of the 17018 residence and the remainder of the ditch was dry. Since the ditch: 1) conveys entirely artificially collected stormwater runoff and 2) was cut through an upland where no stream previously existed, the ditch should not be considered a stream by the City of Renton or any other regulatory jurisdiction. Conclusion No wetlands or streams were identified on or immediately adjacent the site. This determination is based on a field investigation during which no hydrophytic plant communities, hydric soils, or evidence of wetland hydrology were observed. If you have any questions regarding the reconnaissance, please give me a call. Sincerely, ALTMANN OLIVER ASSOCIATES, LLC John Altmann Ecologist King County, Pictometry International Corp., King County Figure 1 Date: 5/21/2016 Notes: ±The information included on this map has been compiled by King County staff from a variety of sources and is subject to changewithout notice. King County makes no representations or warranties, express or implied, as to accuracy, completeness, timeliness,or rights to the use of such information. This document is not intended for use as a survey product. King County shall not be liablefor any general, special, indirect, incidental, or consequential damages including, but not limited to, lost revenues or lost profitsresulting from the use or misuse of the information contained on this map. Any sale of this map or information on this map isprohibited except by written permission of King County.