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Home My WebLink AboutF_RS_TIR_170824 FINAL TECHNICAL INFORMATION REPORT Allura at Tiffany Park S.E. 18th Street and 124th Place S.E. Renton, Washington Prepared for: Mainvue WA, LLC 1110 - 112th Ave NE, Suite 202 Bellevue, WA 98004 February 23, 2017 Revised March 9, 2017 Revised May 1, 2017 Our Job No. 16055 CIVIL ENGINEERING, LAND PLANNING, SURVEYING 18215 72ND AVENUE SOUTH KENT, WA 98032 (425) 251-6222 (425) 251-8782 FAX BRANCH OFFICES ¨ TUMWATER, WA ¨ LONG BEACH, CA ¨ WALNUT CREEK, CA ¨ SAN DIEGO, CA www.barghausen.com 08/23/17 LUA-13001572 U-16006368 PR-13007339 R-3923 FINAL IN COMPIANCE WITH CITY OF RENTON STANDARDS DEVELOPMENT ENGINEERING Ann Fowler 08/24/2017 SURFACE WATER UTILITY rstraka 08/28/2017 Stormwater Drainage Report Allura at Tiffany Park Renton, Washington Our Job No. 16055 16055.016.doc TABLE OF CONTENTS 1.0 PROJECT OVERVIEW Figure 1 – TIR Worksheet Figure 2 – Site Location Figure 3 – Drainage Basins, Subbasins, and Site Characteristics Figure 4 – Soils Figure 5 - FEMA Map 2.0 CONDITIONS AND REQUIREMENTS SUMMARY 2.1 Analysis of the Core Requirements 2.2 Analysis of the Special Requirements 2.3 SEPA and Hearing Examiner Conditions 3.0 OFF-SITE ANALYSIS 4.0 FLOW CONTROL AND WATER QUALITY FACILITY ANALYSIS AND DESIGN A. Existing Site Hydrology B. Developed Site Hydrology C. Performance Standards D. Flow Control System E. Water Quality System 5.0 CONVEYANCE SYSTEM ANALYSIS AND DESIGN 6.0 SPECIAL REPORTS AND STUDIES 6.1 Reserve at Tiffany Park - Hydraulic Assessment for Offsite Storm System prepared by Ed McCarthy, PE, PS dated February 24, 2017 6.2 Allura at Tiffany Park - Wetland Hydrology Analysis prepared by Ed McCarthy, PE, PS dated October 27, 2016 6.3 Revised Tree Protection Plan - Reserve at Tiffany Park prepared by Washington Forestry Consultants dated October 4, 2016 6.4 Geotechnical Engineering Study Allura at Tiffany Park prepared by Earth Solutions NW, LLC dated November 11, 2016 7.0 OTHER PERMITS 7.1 Postmaster / Mailbox Locations Approval 7.2 Roadway Easement and Agreement for 124th 7.3 NPDES Permit dated March 22, 2017 8.0 CONSTRUCTION STORMWATER POLLUTION PREVENTION PLAN (CSWPPP) ANALYSIS AND DESIGN 16055.016.doc 9.0 BOND QUANTITIES, FACILITY SUMMARIES, AND DECLARATION OF COVENANT 9.1 Bond Quantities 9.2 Facility Summary Form 10.0 OPERATIONS AND MAINTENANCE MANUAL APPENDIX APPENDIX A - Lower Cedar River Basin and Nonpoint Pollution Action Plan Tab 1.0 16055.016.doc 1.0 PROJECT OVERVIEW The proposed Plat of Reserve at Tiffany Park is a single-family residential project consisting of 94 lots zoned R8. The project is 21.66 acres in size containing four tax parcels (212305-9044, 212305-9051, 212305-9054, and 212305-9061). The site is located at the dead end of S.E. 18th Street near the intersection of Monroe Avenue S.E. in a portion of Section 21, Township 23 North, Range 5 East, W.M., in the City of Renton. The site is polygonal in shape and ties into two existing road stubs. The first is located in the northwest corner of the site at the dead-end of S.E. 18th Street. The second road stub is located to the southwest of the site on the southern side of the Cedar River Pipeline at the dead-end of 124th Place S.E. These road stubs are to be tied into and will be extended into the site to provide public access and circulation. This site is undeveloped and is currently zoned R8; with a majority of the site being composed of second-growth forest. The elevations of the site range from 456 to 398. There are four wetlands located on site; three of them are Category 2, with one Category 3. The site is entirely surrounded by existing single family residences. Along the east property line is the Mercer Island Pipe Line R/W. Along the south boundary is the Cedar River Pipeline R/W. Access to the site from 124th Place S.E required the developer to an access easement through the Cedar River Pipeline R/W this easement is provided in section 7.1 of this report. On-site soils are mapped as mostly Alderwood, with a small portion along the southern boundary mapped as Arents. Please refer to the Soils Map in this section. All drainage calculations were modeled as till soils. The project will be constructing roadways consisting of curb and gutter, sidewalk, and street trees. The site will tie into the existing roads at the dead-ends of S.E. 18th Street and 124th Place S.E. All roads for this project have been designed to be 26 feet wide, with an 8-foot planter strip at the back of curb and a 5-foot sidewalk (both sides). Overall the proposed public right-of-way is to be 53 feet in width. The topography on site is gentle and rolling. The site generally slopes from east to west from elevation 456 to 398. The project will be mass graded with cuts and fills balanced on-site. The wetland areas will remain undisturbed along with portions of their buffers. Buffer averaging is proposed. Other portions of the site will remain undisturbed in an effort to preserve as many existing trees as possible. The drainage facilities are required to meet the requirements of the 2009 King County Surface Water Design Manual (KCSWDM) and the 2010 City of Renton Amendments to the KCSWDM. The drainage design shall meet at a minimum the Flow Control Duration Standard - Matching Forested and Basic Water Quality Treatment. The drainage facility located in Tract A is a detention pond sized for Level 2 Flow Control. Water quality will be met by the use of a StormFilter for this project. The project will be discharging the drainage from the pond to the existing drainage system within S.E. 18th Street near the intersection of Lake Youngs Way SE. Please refer to Section 4.0 for detailed drainage calculations. Figure 1 TIR Worksheet KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL TECHNICAL INFORMATION REPORT (TIR) WORKSHEET 2009 Surface Water Design Manual 3/09/17 1 16055.018.doc Part 1 PROJECT OWNER AND PROJECT ENGINEER Part 2 PROJECT LOCATION AND DESCRIPTION Project Owner MainVue WA, LLC Phone (425) 646-4022 Address 1110 112th AVE NE, Suite 202 Bellevue, WA 98004 Project Engineer Barry Talkington Company Barghausen Consulting Engineers , Inc. Phone (425) 251-6222 Project Name Allura at Tiffany Park DDES Permit # Location Township 23N Range 05E Section 21 Site Address East of Intersection of S.E. 18th ST & Monroe AVE S.E., Renton, WA Part 3 TYPE OF PERMIT APPLICATION Part 4 OTHER REVIEWS AND PERMITS Landuse Services Subdivision / Short Subd. / UPD Building Services M/F / Commercial / 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 Type of Drainage Review Full / Targeted / (circle): Large Site Date (include revision November 11, 2016 dates): March 9, 2017 Date of Final: Site Improvement Plan (Engr. Plans) Type (circle one): Full / Modified / Small Site Date (include revision November 11, 2016 dates): February 27, 2017 Date of Final: 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 3/09/17 2 16055.018.doc 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: Lower Cedar River 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 AgC 6-15 percent High AmC 6-15 percent High High Groundwater Table (within 5 feet) Sole Source Aquifer Other Seeps/Springs Additional Sheets Attached KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL TECHNICAL INFORMATION REPORT (TIR) WORKSHEET 2009 Surface Water Design Manual 3/09/17 3 16055.018.doc Part 11 DRAINAGE DESIGN LIMITATIONS REFERENCE LIMITATION / SITE CONSTRAINT Core 2 – Offsite Analysis Sensitive/Critical Areas SEPA Other Additional Sheets Attached Part 12 TIR SUMMARY SHEET (provide one TIR Summary Sheet per Threshold Discharge Area) Threshold Discharge Area: (name or description) Discharge to existing conveyance system at SE 18th ST & Lake Youngs Way SE Core Requirements (all 8 apply) Discharge at Natural Location Number of Natural Discharge Locations: 1 Offsite Analysis Level: 1 / 2 / 3 dated: Flow Control Level: 1 / 2 / 3 or Exemption Number (incl. facility summary sheet) Small Site BMPs Conveyance System Spill containment located at: N/A 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 Provided: Yes / No Liability Water Quality Type: Basic / Sens. Lake / Enhanced Basicm / Bog (include facility summary sheet) or Exemption No. Landscape Management Plan: Yes / No Special Requirements (as applicable) Area Specific Drainage Type: CDA / SDO / MDP / BP / LMP / Shared Fac. / None Requirements Name: Floodplain/Floodway Delineation Type: Major / Minor / Exemption / None 100-year Base Blood Elevation (or range): Datum: Flood Protection Facilities Describe: Source Control Describe landuse: (comm./industrial landuse) Describe any structural controls: KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL TECHNICAL INFORMATION REPORT (TIR) WORKSHEET 2009 Surface Water Design Manual 3/09/17 4 16055.018.doc 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 Control 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 Vault Biofiltration Wetpool Media Filtration Oil Control Spill Control Flow Control BMPs Other StormFilter KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL TECHNICAL INFORMATION REPORT (TIR) WORKSHEET 2009 Surface Water Design Manual 3/09/17 5 16055.018.doc 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. March 9, 2017 Signed/Date Figure 2 Site Location barg h au senCONSUL T ING EN G I N E E R S ,INC.Horizontal: Scale: Vertical: For: Title: VICINITY MAP Job Number 18215 72ND AVENUE SOUTH KENT, WA 98032 (425) 251-6222 (425) 251-8782 CIVIL ENGINEERING, LAND PLANNING, SURVEYING, ENVIRONMENTAL SERVICES N.T.S.N/A 16055 DATE: 11/04/13 Reserve at Tiffany Park Renton, Washington P:\16000s\16055\exhibit\graphics\16055 vmap.cdr REFERENCE: Thomas Guide (2006) SITE barg h au senCONSUL T ING EN G I N E E R S ,INC.Horizontal: Scale: Vertical: For: Title: ASSESSOR MAP Job Number 18215 72ND AVENUE SOUTH KENT, WA 98032 (425) 251-6222 (425) 251-8782 CIVIL ENGINEERING, LAND PLANNING, SURVEYING, ENVIRONMENTAL SERVICES N.T.S.N/A 16055 DATE: 11/04/13 Reserve at Tiffany Park Renton, Washington P:\16000s\16055\exhibit\graphics\16055 amap.cdr SITE REFERENCE: King County Department of Assessments (Dec. 2011) ALLURA AT TIFFANY PARKALLURA AT TIFFANY PARK FOR Figure 3 Drainage Basins, Subbasins, and Site Characteristics Figure 4 Soils Map barg h au senCONSUL T ING EN G I N E E R S ,INC.Horizontal: Scale: Vertical: For: Title: SOIL SURVEY MAP Job Number 18215 72ND AVENUE SOUTH KENT, WA 98032 (425) 251-6222 (425) 251-8782 CIVIL ENGINEERING, LAND PLANNING, SURVEYING, ENVIRONMENTAL SERVICES N.T.S.N/A 16055 DATE: 11/04/13 Reserve at Tiffany Park Renton, Washington P:\16000s\16055\exhibit\graphics\16055 soil.cdr REFERENCE: USDA, Natural Resources Conservation Service LEGEND: AgC = Alderwood gravelly sandy loam, 6-15% slopes SITE AmC = Arents, Alderwood material, 6-15% slopes Figure 5 FEMA Map barg h au senCONSUL T ING EN G I N E E R S ,INC.Horizontal: Scale: Vertical: For: Title: FEMA MAP Job Number 18215 72ND AVENUE SOUTH KENT, WA 98032 (425) 251-6222 (425) 251-8782 CIVIL ENGINEERING, LAND PLANNING, SURVEYING, ENVIRONMENTAL SERVICES N.T.S.N/A 16055 DATE: 11/04/13 Reserve at Tiffany Park Renton, Washington P:\16000s\16055\exhibit\graphics\16055 fema.cdr REFERENCE: Federal Emergency Management Agency (Portion of Map 53033C0983 F, May 1995) SITE Tab 2.0 16055.016.doc 2.0 CONDITIONS AND REQUIREMENTS SUMMARY 2.1 Analysis of the Core Requirements Core Requirement No. 1: Discharge at the Natural Location. Response: The storm drainage from the project will be conveyed to a detention vault that will outlet to the existing downstream drainage system in S.E. 18th Street per the City of Renton’s request. This will serve as our project discharge location. A portion of the lots along the existing wetlands (Wetland A, Wetland B and Wetland C) will discharge their roof drains into the wetland areas to maintain wetland hydrology. Please reference the Wetland Hydrology Analysis prepared by Ed McCarthy, PE, PS dated October 27, 2016 located in section 6.2 of this report. Runoff from these wetlands will be collected and routed to the on-site drainage facility. Core Requirement No. 2: Off-Site Analysis. Response: A Level 1 Downstream Drainage Analysis is provided in Section 3.0 of this Technical Information Report. A more detailed Level 2 Downstream Drainage Analysis is provided in section 6.1 of this report as requested by SEPA condition 2. Core Requirement No. 3: Flow Control. Response: The project is providing a detention facility which is designed for Flow Control Duration Standard Matching Forested Site Conditions. At a minimum the sites developed discharge release will match the predeveloped durations for the range of predeveloped discharge rates from 50-percent of the 2-year peak flow up to the 50-year peak flow as well as peak discharge rates for the 2-year and 10-year return periods Core Requirement No. 4: Conveyance System. Response: The conveyance and backwater analysis has been provided in Section 5.0 of this report. Core Requirement No. 5: Erosion and Sediment Control. Response: Temporary erosion control measures have been provided in Section 8.0 of this report. Core Requirement No. 6: Maintenance and Operations. Response: A Maintenance and Operations Manual has been provided in Section 10.0 of this report. Core Requirement No. 7: Financial Guarantees and Liability. Response: The project will provide a Bond Quantity Worksheet to establish a bond amount for installation of public infrastructure, including water, sewer, storm, installation of the detention facility and water quality filters, and drainage facility restoration and site stabilization financial guarantee prior to construction. Core Requirement No. 8: Water Quality. 16055.016.doc Response: This project utilizes a StormFilter sized for Basic Water Quality Treatment. Sizing calculations have been provided and prepared by Contech and are located within section 4.0 of this report. 2.2 Analysis of the Special Requirements Special Requirement No. 1: Other Adopted Area-Specific Requirements. Response: The proposed project is not located in a designated Critical Drainage Area. Special Requirement No. 2: Flood Hazard Area Delineation. Response: As indicated by the FEMA Map included in this report (portion of Map 53033C0983 F, May 1995), the proposed site does not lie within a floodplain or floodway or a stream, so this special requirement does not apply. Special Requirement No. 3: Flood Protection Facilities. Response: This project does not rely on an existing flood protection facility or propose to modify or construct a new flood protection facility, so this special requirement does not apply. Special Requirement No. 4: Source Control. Response: The project does not require a commercial building or commercial site development permit, so this special requirement does not apply. Special Requirement No. 5: Oil Control. Response: This site is not classified as a High Use Site given the criteria in the 2009 KCSWDM, so this special requirement does not apply and no special control treatment is necessary. Special Requirement No. 6: Aquifer Protection Area Response: The project site is located within a Zone 2 Aquifer Protection Area. Per the City of Renton Amendments to the King County Surface Water Design Manual, the only requirements are to provide liners to open water drainage facilities and conveyance systems. This project proposes to provide a closed detention facility (underground vault) and closed conveyance system; therefore, this Special Requirement is not applicable. - 1 - 16055.017.docx DETERMINATION OF NON-SIGNIFICANCE-MITIGATED (DNSM] MITIGATION MEASURES AND ADVISORY NOTES Project Nos. LUA13-001572, ECF, PP, CAR Henley USA LLC The Reserve at Tiffany Park MITIGATION MEASURES: CONDITION RESPONSE 1. All earthwork performed, implemented by the applicant, shall be consistent with the recommendations of the geotechnical report, prepared by Associated Earth Sciences, Inc., dated September 28, 2012. This condition has revised per the Hearing Examiners Conditions dated January 26th, 2015. Per hearing examiner condition #1 it now reads as follows. "All earthwork performed, implemented by the applicant, shall be consistent with the recommendations of the geotechnical report, prepared by Associated Earth Sciences, Inc., dated September 28, 2012 or consistent with the recommendations of the final City - approved geotechnical remit." 2. The final drainage report shall include a more detailed downstream analysis. Pursuant to KCSWDM 1.2.2.1, a Level 2 downstream analysis for 1/4 mile from the project site is required. The applican t should note that Level 3 flow control could be required as part of the Level 2 downstream analysis. A revised final drainage report and associated plans, based on the 2009 King County Surface Water Design Manual as amended by the City of Renton, is required to be submitted to the satisfaction of the Plan Reviewer prior to construction permit approval. The applicant shall also be required to comply with, and implement, any recommended mitigation measures included in the revised Drainage Report. Condition acknowledged a level 2 downstream analysis has been included within the revised drainage report. 3. The applicant shall be required to retain 30% of the significant trees on site with exclusions for those trees that are considered dead, diseased, or dangerous, trees located within proposed rights-of- way, and trees located within the critical areas and their associated buffers. The proposed site preserves more than 30% of the existing significant trees within designated open space tracts. 4. The applicant shall be required to provide, to the Current Planning Project Manager, tree retention inspection/monitoring r eports after initial clearing, final grading, and annually for two years by a Condition acknowledged. - 2 - 16055.017.docx CONDITION RESPONSE qualified professional forester. The inspection/monitoring reports shall identify any retained trees that develop problems due to changing site conditions and prescribe mitigation. The applicant shall also be required to comply with, and implement, any recommended mitigation measures included in the inspection reports. 5. The applicant shall be required to submit a mitigation plan, prepared by a qualified professional, which will address vermin abatement during project grading and site improvements. The vermin abatement mitigation plan shall be submitted to, and approved by, the Current Planning Project Manager prior to construction permit approval. The applicant shall also be required to comply and implement any recommended mitigation according to an approved plan. A vermin abatement plan will be provided to the Current Planning Project Manager prior to construction permit approval. 6. A minimum 15-foot wide partially sight obscuring landscape buffer along the perimeter of the site shall be provided. The 15-feet would allow for the offset of tree planting, as opposed to a linear tree line, which would create a more natural buffer in keeping with the existing character of the site. Such landscaping or landscape plus fencing shall be, at minimum, 6-feet high at maturity and at least 50% sight-obscuring. Existing mature trees are located within this 15 foot buffer should be maintain and protected during construction unless determined by an Arborist that such tree is dead, diseased, or dangerous. This condition has revised per the Hearing Examiners Conditions dated January 26th, 2015. Per hearing examiner condition #1 it now reads as follows. "The applicant shall revise its landscaping plan to provide for a 10 foot wide on-site street frontage landscape strip as required by RMC 4-4-070(F)(1) for all lots and a 10 foot wide, site obscuring perimeter landscaping adjacent to areas where the retaining walls are four or more feet in height. Landscaping at maturity must exceed the height of the adjacent retaining wall. The final detailed landscape plan shall be submitted to and approved by the Current Planning Project Manager prior to construction permit approval. Such landscaping shall include a mixture of trees, shrubs, and groundcover as approved by the Department of Community and Economic Development." 7. The applicant shall install a STOP sign with a stopline in thermoplastic on the southbound approach of Monroe Ave SE to SE 18th St in order to address the sight distance concerns at this intersection prior to Final Plat approval. The final design is subject to final construction permit review prior to construction permit issuance. Condition acknowledged. The installation of a stop sign and stopline are shown on the engineering plans and will be installed prior to final plat approval. 8. The applicant shall submit a revised TIA including an analysis of the 124th Place SE and SE 158th St intersection sight distance and Condition acknowledged. - 3 - 16055.017.docx CONDITION RESPONSE recommend appropriate mitigation. The revised TIA shall be submitted to, and approved by, the Plan Reviewer prior to utility construction permits. The applicant shall also be required to comply with, and implement, any recommended mitigation measures included in the revised TIA. 9. The applicant shall install directional information signage (white letters on green background) at S Puget Drive and 116th Ave SE facing west prior to Final Plat approval. The signs shall read "TIFFANY PARK" with a left arrow and "CASCADE" with a right arrow. The final design is subject to final construction permit review prior to construction permit issuance. This sign appears to have been installed at some point in 2015. This condition is therefore satisfied. 10. An additional CROSSROAD (W2-1 symbol) warning sign with a 15MPH advisory speed shall be installed by the applicant on the southwest directional approach to Beacon Way SE, along the north side of SE 16th St (east of Beacon Way SE). The final design is subject to final construction permit review prior to construction permit issuance. Condition acknowledged. The installation of a crossroad warning sign and a 15mph advisory speed sign are shown on the engineering plans and will be installed prior to final plat approval. 11. The applicant shall provide a marked crosswalk at the intersection of SE 18th St and Lake Youngs Way SE prior to Final Plat approval. The final design is subject to final construction permit review prior to construction permit issuance. Condition acknowledged. A marked crosswalk at the intersection of SE 18th St and Lake Yours Way SE is shown on the engineering plans and will be installed prior to final plat approval. HEARING EXAMINER'S DECISION Henley USA LLC The Reserve at Tiffany Park Dated January 26, 2015 CONDITION RESPONSE 1. The applicant shall comply with the mitigation measures issued as part of the Determination of Non-Significance Mitigated, dated September 22, 2014 except as modified below: a. MDNS Condition 1 shall be revised as follows: - 4 - 16055.017.docx CONDITION RESPONSE All earthwork performed, implemented by the applicant, shall be consistent with the recommendations of the geotechnical report, prepared by Associated Earth Sciences, Inc., dated September 28, 2012 or consistent with the recommendations of the final City-approved geotechnical remit Condition acknowledged. b. MDNS Condition 6 shall be stricken and replaced with the following [as modified by the Ruling on Reconsideration]: The applicant shall revise its landscaping plan to provide for a 10 foot wide on-site street frontage landscape strip as required by RMC 4-4-070(F)(1) for all lots and a 10 foot wide, site obscuring perimeter landscaping adjacent to areas where the retaining walls are four or more feet in height. Landscaping at maturity must exceed the height of the adjacent retaining wall. The final detailed landscape plan shall be submitted to and approved by the Current Planning Project Manager prior to construction permit approval. Such landscaping shall include a mixture of trees, shrubs, and groundcover as approved by the Department of Community and Economic Development. All walls bordering the perimeter of the site are less than 4 feet in height when not provided a 10 foot wide landscaping buffer. Please reference the associated Landscape plans for further information regarding proposed plantings. 2. The applicant shall be required to demons trate compliance with the minimum 50-foot lot width requirement for all lots with less than 50 feet in width at the foremost points (where the side lot lines intersect with the street right-of-way line) pursuant to RMC 4-11- 120. The average distance between the side lines connecting front and rear lot lines shall be submitted to the Current Planning Project Manager prior to construction permit approval. A revised Preliminary Plat Plan has been included within the Construction Permit Plan Set. All lots comply with RMC 4-11- 120. 3. Condition No. 3 has been deleted as directed in the Ruling on Reconsideration. N/A 4. The applicant shall be required to submit a revised plat and landscaping plan, which are elements of the City's required construction plan set, depicting curb bulbouts at street intersections where on-street parking is located or calling for no curb bulbouts and installation of "no parking" designations where street parking is prohibited at street intersections. The revised plat and landscaping plan shall be submitted to and approved by the Current Planning Project Manager prior to construction permit approval. The developer has elected to not provide bulbouts at street intersections within the development. "No Parking" signs are called out on the appropriate plan sheets within the Construction Permit Plan Set. - 5 - 16055.017.docx CONDITION RESPONSE 5. The applicant shall eliminate individual access directly from internal public streets for those lots abutting private streets and/or shared driveway access easements, specifically Lots 12-14, Lots 15-17, Lots 38-40 and Lots 78-81 in shared driveways. Said lots shall be required to take access from the abutting private street and/or access easement and shall not exceed access thresholds pursuant to RMC 4-6-060.J and K. Lot 11 may access the public street directly. The revised plat plan shall be submitted to, and approved by, the Current Planning Project Manager prior to construction permit approval. Furthermore, the access restriction for such lots is required to be noted on the face of the Final Plat prior to recording. The lot numbering referenced in the above condition reflects the original 97-lot version submitted as Exhibit 2 to the Hearing Examiner. As part of the approval process, the plat was approved for 96 lots. Due to this revision as well as the proposed revisions listed above, the lot numbering has changed. Lots 12 to 14 have been renumbered to Lots 11 to 13 and will take shared access from Tract N. Lots 15 to 17 have been renumbered to Lots 14 to 16 and will take shared access from Tract O. Lots 38 to 40 have been renumbered to Lots 37 to 39 and will take shared access from Tract P. Lots 78 to 81 have been renumbered to Lots 75 to 78 and will take shared access from Tract Q. 6. The applicant shall revise the proposed mitigation p lan to depict all retaining walls on site, including lock & load walls on the north and east sides of Wetlands B and C. The applicant shall also identify if proposed walls are anticipated to impact critical area buffers and provide appropriate mitigation for such impacts. A Final Mitigation Plan, pursuant to RMC 4-8-120.W, shall be submitted to, and approved by the Current Planning Project Manager prior to construction permit approval. Condition acknowledged. The Mitigation Plans have been revised to address this requirement. 7. The temporary buffer impacts consisting of minor intrusions or disturbance from construction activities shall be restored with appropriate grading, soil amendments, and the planting of native species to the satisfaction of the Current Planning Project Manager. The revised mitigation plan shall be submitted to and approved by, the Current Planning Project Manager prior to construction permit approval. Condition acknowledged. The Mitigation Plans have been revised to address this requirement. 8. The existing wetland mitigation plan already assures that 1,331 square feet of additional wetland buffer area is being provided to mitigate for both existing buffer impacts to Wetland E that are not associated with the Plat, as well as the loss of 14 square feet of the Wetland E buffer which loss is associated with the extension of SE 18th Street. To provide an additional offset for the impacts resulting from the requested exemption associated with the fill of 14 square feet of buffer to extend SE 18th Street. The applicant has agreed to provide and shall provide enhancement to the Wetland E buffer immediately abutting SE 18th Street, as well as enhanced plantings adjoining that buffer area within Tract M. A revised Condition acknowledged. The Mitigation Plans have been revised to address this requirement. - 6 - 16055.017.docx CONDITION RESPONSE mitigation plan shall be submitted to, and approved by, the Current Planning Project Manager prior to construction permit approval. 9. The applicant shall be required to establish a Native Growth Protection Easement over those parts of the site encompassing wetlands and their associated buffers and place fencing and signage along the outer buffer edge prior to Final Plat approval. The Native Growth Protection Easement and the associated fencing shall be designated on the Landscaping Plans. 10. The applicant shall be required to submit a fill source statement if fill materials are brought to the site in order to the City to ensure only clean fill is imported prior to construction. Condition acknowledged. 11. The applicant shall provide a final Tree Retention Plan, complying with the 30% tree retention SEPA mitigation measure while demonstrating proposed retaining walls would not impact trees proposed for retention. The Final Tree Retention Plan shall be submitted to, and approved by, the Current Planning Project Manager prior to construction permit approval. Condition acknowledged. The proposed site preserves more than 30% of the existing significant trees within designated open space tracts. 12. The applicant shall submit a revised plat plan, which is an element of the City's required construction plan set, depicting a safe pedestrian crossing, across the 124th Place SE extension, for the Seattle Waterline Pedestrian Trail. The revised plat plan, as part of the construction plan set, shall be submitted to, and approved by the Current Planning Project Manager, Community Services Department, and the Transportation Department prior to construction permit approval. The following note has been added to the Preliminary Plat - Horizontal Control Plan: "Safe pedestrian crossing for the Seattle W aterline Pedestrian Trail across 124th PL SE shall be provided. Refer to Sheet 26 for specific details." 13. The applicant shall be required to obtain right-of-way or a public access easement through the Cedar River Pipeline, for the extension of 124th Place SE, to the satisfaction of the Plan Reviewer prior to construction permit approval. Condition acknowledged. And ingress egress easement had been acquired through the Cedar River Pipeline. Please see applicable easement documents provided in Section 7.2 of this report. 14. Pedestrian lighting shall be depicted on the lighting plan at the entrances of Tracts C and E (from the proposed right-of-way). The lighting plan shall be submitted to, and approved by, the Current Planning Project Manager and the Plan Reviewer prior to construction permit approval. Pedestrian lighting has been provided near the entrances of both tracts and can be found on both the construction and lighting plans. 15. The Preliminary Plat plan shall be revised so that no more than 4 lots may gain access via a shared driveway and that at least one such lot shall meet minimum lot width requirements along a street As noted above, lot numbering has changed. As such, Lots 14, 17, and 38 have all been renumbered to Lots 13, 16, and 27. These lots have all been widened to 35 feet at the right of way line, as - 7 - 16055.017.docx CONDITION RESPONSE frontage pursuant to RMC 4-7-170.D (a minimum of 80% or the required lot width/40 feet or 35 feet along a street curve). The lot(s) which provides physical frontage along the street shall only be allowed vehicular access from the shared private driveway. In order to provide shared access, Lots 14, 17 and 3 shall be widened to 35 feet and take primary access from the shared driveway. The revised plat plan shall be submitted to and approved by the Current Planning Project Manager prior to construction permit approval. they intersect a curve, and will take access from Tracts N, O, and P respectively. 16. The plat plan shall be revised so that all lots have no less than a 40-foot lot width where side lot lines intersect with the street right of way or for radial lots be a minimum of 35 feet in width. Sp ecifically, proposed Lots 14, 17, and 38 would be required to be widened to 35 feet in order to comply with the condition. The revised plat plan shall be submitted to and approved by the Current Planning Project Manager prior to construction permit approval. As noted above, lot numbering has changed. As such, Lots 14, 17, and 38 have all been renumbered to Lots 13, 16, and 27. These lots have all been widened to 35 feet at the right of way line. 17. The applicant shall submit a revised plat plan depicting the elimination of all pipestem lots (lots which are less than 40 feet in width where the side lot lines intersect with the street right-of-way or for radial lots are less than 35 feet) within the subdivision. Specifically, proposed Lots 12, 14, 15, 17, 38, 40, and 79 would be required to be eliminated or revised to meet minimum frontage width requirements. The applicant may also submit an alternative plat plan which includes a combination of all lots fronting onto a public street meeting minimum lot widths and those portions of the lots now proposed for shared driveway/access easements could be placed in Shared Driveway Tracts with easements placed over them pursuant to RMC 4-6-060, Street Standards. The revised plat plan shall be submitted to and approved by the Current Planning Project Manager prior to construction permit approval. As noted above, lot numbering has changed. Lots 12 to 14 have been renumbered to Lots 11 to 13 and will take shared access from Tract N. Lots 15 to 17 have been renumbered to Lots 14 to 16 and will take shared access from Tract O. Lots 38 to 40 have been renumbered to Lots 37 to 39 and will take shared access from Tract P. Lots 78 to 81 have been renumbered to Lots 75 to 78 and will take shared access from Tract Q. Shared access easements will be provided over these tracts. 18. Any proposal to convert the Stormwater vault wit hin Tract A to a Stormwater detention pond be considered a Major Plat Amendment subject to the requirements outlined under RMC 4-7-080M.2. Condition acknowledged. 19. The applicant shall be required to create a homeowners' association and maintenance agreement(s) for the shared utilities, landscape areas and maintenance and responsibilities for all shared improvements of this development. A draft of the A homeowner's association and maintenance agreement for all shared utilities, landscape areas and maintenance and responsibilities for all shared improvements of this development shall be provided prior to the recording of the final plat. - 8 - 16055.017.docx CONDITION RESPONSE document(s) shall be submitted to Current Planning Project Manager for review and approval by the City Attorney and Property Services section prior to the recording of the final plat. 20. The applicant shall submit the results of the Phase I Environmental Site Assessment to the City for review. Appropriate mitigation, if any, shall be completed prior to issuance of building permits. Condition acknowledged. 21. All road names shall be approved by the City. Condition acknowledged. 22. Easements may be required for the maintenance and operation of utilities as specified by the Department. Easements will be provided for their subject utilities upon their request. 23. Sanitary sewers shall be provided by the developer at no cost to the City and designed in accordance with City standards. Side sewer lines shall be installed eight feet (8') into each lot if sanitary sewer mains are available, or provided with the subdivision development. Condition acknowledged sewer stubs will extend at a minimum of 8 feet into the lots. 24. Any cable TV conduits shall be undergrounded at the same time as other basic utilities are installed to serve each lot. Conduit for service connections shall be laid to each lot line. Condition acknowledged. 25. Concrete permanent control monuments shall be established at each and every controlling corner of the subdivision. Interior monuments shall be located as determined by the Department. All surveys shall be per the City of Renton surveying standards. All other lot corners shall be marked per the City surveying standards. The subdivider shall install all street name signs necessary in the subdivision. Condition acknowledged. 26. [This condition added as directed by the Ruling on Reconsideration to address Roof run-off]. Roof run-off that impacts wetlands shall not be allowed mix with polluting surfaces. Category 2 wetlands may not be structurally or hydrologically engineered for runoff quantity or quality control as required by KCSWDM Reference 5. City staff shall require design adjustments as authorized by KCSWDM 1.2 to the extent necessary to prevent adverse impacts to wetland hydrology caused by roof runoff. Roof run-off being directed to the wetlands onsite in order to maintain their hydrology will not be mixed with run-off from pollution generating surfaces. SEPA and Hearing Examiners Conditions 2.3 Tab 3.0 16055.016.doc 3.0 OFF-SITE ANALYSIS Task 1 STUDY AREA DEFINITION AND MAPS The proposed Plat of Reserve at Tiffany Park is a single-family residential project consisting of 94 lots zoned R8. The project is 21.66 acres in size containing four tax parcels (212305-9044, 212305-9051, 212305-9054, and 212305-9061). The site is located at the dead end of S.E. 18th Street near the intersection of Monroe Avenue S.E. in a portion of Section 21, Township 23 North, Range 5 East, W.M., in the City of Renton. The site is polygonal in shape and ties into two existing road stubs. The first is located in the northwest corner of the site at the dead-end of S.E. 18th Street. The second road stub is located to the southwest of the site on the southern side of the Cedar River Pipeline at the dead-end of 124th Place S.E. These road stubs are to be tied into and will be extended into the site to provide public access and circulation. This site is undeveloped and is currently zoned R8; with a majority of the site being composed of second- growth forest. The elevations of the site range from 456 to 398. There are five wetlands located on site; three of them are Category 2 and two are Category 3. The site is entirely surrounded by existing single family residences. Along the east property line is the Mercer Island Pipe Line R/W. Along the south boundary is the Cedar River Pipeline R/W. Access to the site from 124th Place S.E required the developer to an access easement through the Cedar River Pipeline R/W this easement is provided in section 7.1 of this report. On-site soils are mapped as mostly Alderwood, with a small portion along the southern boundary mapped as Arents. Please refer to the Soils Map in this section. All drainage calculations were modeled as till soils. The project will be constructing roadways consisting of curb and gutter, sidewalk, and street trees. The site will tie into the existing roads at the dead-ends of S.E. 18th Street and 124th Place S.E. All roads for this project have been designed to be 26 feet wide, with an 8-foot planter strip at the back of curb and a 5-foot sidewalk (both sides). Overall the proposed public right-of-way is to be 53 feet in width. The topography on site is gentle and rolling. The site generally slopes from east to west from elevation 456 to 398. The project will be mass graded with cuts and fills balanced on-site. The wetland areas will remain undisturbed along with portions of their buffers. Buffer averaging is proposed. Other portions of the site will remain undisturbed in an effort to preserve as many existing trees as possible. The drainage facilities are required to meet the requirements of the 2009 King County Surface Water Design Manual (KCSWDM) and the 2010 City of Renton Amendments to the KCSWDM. The drainage design shall meet at a minimum the Flow Control Duration Standard Matching Forested Site Conditions and Basic Water Quality Treatment. The drainage facility located in Tract A is a detention vault sized for Flow Control Duration Standard Matching Forested Site Conditions. Water quality will be met by the use of a StormFilter for this project. In order to provide the necessary depth within the detention facility a new conveyance system will be constructed within S.E. 18th Street and connect to the existing storm line at the intersection of S.E. Lake Youngs Way. Please refer to Section 4.0 for detailed drainage calculations. UPSTREAM DRAINAGE ANALYSIS: Upstream of the site to the northeast is the existing Mercer Island Pipeline. This pipeline is approximately 60 feet wide. The pipeline is fully cleared with grass overgrowth and is slightly crowned along the center of the right-of-way for its full length adjacent to the project site. Due to the inability to efficiently bypass the 30-foot-wide portion that flows onto the project site, it is proposed that this region of runoff be collected and routed to the on-site drainage facility. As such, this area is being considered as part of the pre-developed site and is not part of the upstream basin. 16055.016.doc There is also an upstream basin to the east of the Mercer Island Pipe Line R/W that is tributary to the on- site Wetland "D". This basin consists of runoff from a portion of 129th Place S.E. and the 19th Court S.E. culdesac along with the surrounding homes. Runoff from this basin is collected and routed by a series of catch basins and storm pipes to an existing ditch along the east side of the pipeline R/W. A twelve-inch culvert crosses the pipeline and discharges runoff into the on-site Wetland "D". Runoff from this upstream basin and from Wetland "D" will be collected in a separate conveyance system and routed through the site to Wetlands "B/C" which they are tributary to in the existing condition. Any potential runoff from Wetlands "B/C" will be collected and routed through the on-site drainage facility. As such, this area is being considered as part of the pre-developed site and is not part of the upstream basin. For further detail please refer to the Upstream Basin Map in Section 1.0. 16055.016.doc TASK 2 RESOURCE REVIEW · Adopted Basin Plans: The site is located within the Mainstem subarea of the Cedar River Basin. The Mainstem subarea is included in the Lower Cedar River Basin and Nonpoint Pollution Action Plan. Refer to Appendix A for the portions of the basin that applies to this project. · Finalized Drainage Studies: This is not applicable. · Basin Reconnaissance Summary Report: This site is located in the Mainstem subarea of the Lower Cedar River Basin, which is covered by the Lower Cedar River Basin and Nonpoint Pollution Action Plan dated July 1997 (included in Appendix A). · Critical Drainage Area Maps: This project will not discharge to any critical areas or wetlands as it is to tie into an existing storm drain conveyance system downstream of the detention and water quality system. As a result no critical areas are to be affected. · Floodplain and Floodway FEMA Maps: Please see the attached FEMA Map (Section 1.0) utilized for this analysis. As indicated on the map the site is located in Zone X and is outside of the 500-year flood plain. · Other Off-Site Analysis Reports: A site investigation was conducted in preparation of this Level 1 Off-Site Drainage Analysis. A Level 2 Off-Site Drainage Analysis as request by SEPA Condition 2 has been provided in Section 6.1 of this report. The United States Department of Agriculture Soils Conservation Service Map is also provided. See Figure 4 – Soils Map in Section 1.0. · Sensitive Areas Folios: Based on a review of the King County Sensitive Areas Map Folios, the site does not contain any On-Site Wetlands, Erosion Sensitive Areas, Land Slide Areas, or any Known Drainage Complaints. However, through field survey and analysis it has been determined that there are five wetlands on site. As a result a formal wetland study is included in Section 6.0. · Road Drainage Problems: This is not applicable. · United States Department of Agriculture King County Soils Survey: Based on the Soils Map (see Figure 4 – Soils Map Section 1.0) for this area, the majority of the site is located in the soils configuration known as Alderwood gravelly sandy loam, and there is a small portion along the south end of the project that is classified as Arents, Alderwood material. · Wetland Inventory Map: Using the COR Maps and NWMaps applications on the City of Renton website there is no known documentation or inventory of wetlands for the project site. However, through field survey and analysis it has been determined that there are five wetlands on site. As a result a formal wetland study is included in Section 6.0. · Migrating River Studies: This is not applicable. · City of Renton Aquifer Protection Zones: Per the City of Renton's GIS Map the project site is located within a Zone 2 Aquifer Protection Area. 16055.016.doc TASK 3 FIELD INSPECTION The field reconnaissance for this Level 1 Off-Site Drainage Analysis was conducted on August 16, 2013 and November 5, 2013 for the purpose of analyzing the proposed project site and its upstream and downstream corridors. The site visit on August 16, 2013 was sunny and dry with no evidence of standing water or ponding along the ditch line north of the Mercer Island Pipeline. The visit on November 5, 2013 was cloudy with rain, with evidence of mild runoff from the cul-de-sac of S.E. 19th Court to its designated collection system. It should be noted that there was some evidence of flowing or standing runoff along the ditch line north of the Mercer Island Pipeline, but at the locations inspected depths did not exceed more than 1 inch. The off-site drainage system was inspected one-quarter mile downstream following the existing closed conveyance system to Tiffany Park Elementary School where the runoff is collected by a 60-inch trunk line and ultimately conveyed northwest to Ginger Creek. 3.1 Conveyance System Nuisance Problems (Type 1) Conveyance system nuisance problems are minor but not chronic flooding or erosion problems that result from the overflow of a constructed conveyance system that is substandard or has become too small as a result of upstream development. Such problems warrant additional attention because of their chronic nature and because they result from the failure of a conveyance system to provide a minimum acceptable level of protection. There were no conveyance system nuisance problems observed during the August 16, 2013 site visit. Furthermore, based on a review of the drainage complaints received from the City of Renton, there is no evidence of past conveyance system nuisance problems occurring in the direct downstream drainage course, as there is a record of none having been submitted. This site will have a Flow Control Duration Standard Matching Forested Site Conditions, which will restrict the flow of the 2-year release rate to 50 percent of the pre-developed site and will provide adequate mitigation to prevent any future drainage complaints as a result of this proposed site development. 3.2 Severe Erosion Problems (Type 2) Severe erosion problems can be caused by conveyance system overflows or the concentration of runoff into erosion-sensitive open drainage features. Severe erosion problems warrant additional attention because they pose a significant threat either to health and safety or to public or private property. Based on our site visit there and the lack of drainage complaints, there was no evidence of or potential for erosion/incision sufficient to pose a sedimentation hazard downstream within the limits of the study. There are no defined drainage channels or ditches leaving the site. All runoff is either infiltrated on site or sheet flows off site where it is collected by the storm drain conveyance systems of the downstream suburban area. Stormwater runoff from the proposed roads will be collected and conveyed to a detention and water quality facility where it will then be discharged by tying into the existing stormwater conveyance system within S.E. 18th Street. As a result no future erosion problems should occur because of this development downstream. 3.3 Severe Flooding Problems (Type 3) Severe flooding problems can be caused by conveyance system overflows or the elevated water surfaces of ponds, lakes, wetlands, or closed depressions. Severe flooding problems are defined as follows: · Flooding of the finished area of a habitable building for runoff events less than or equal to the 100-year event. Examples include flooding of finished floors of homes and 16055.016.doc commercial or industrial buildings. Flooding in electrical/heating systems and components in the crawlspace or garage of a home. Such problems are referred to as "severe building flooding problems." · Flooding over all lanes of a roadway or severely impacting a sole access driveway for runoff events less than or equal to the 100-year event. Such problems are referred to as "severe roadway flooding problems." Based on a review of the FEMA Map (Section 1.0) the proposed site is outside of the 500- year floodplain, and there is no evidence of severe flooding problems encountered during our visit. 16055.016.doc TASK 4 DRAINAGE SYSTEM DESCRIPTION AND PROBLEM DESCRIPTIONS DOWNSTREAM DRAINAGE ANALYSIS: The contents provided within this section of the report are consistent with that which is required for a Level 1 Downstream Drainage Analysis. In the pre-developed condition all downstream drainage currently flows off site onto the properties immediately adjacent to the west or onto S.E. 18th Street where it is collected by the existing stormwater conveyance system. In the developed condition stormwater being discharged from the site will be conveyed to a new catch basin being installed along an existing 18-inch diameter storm drain pipe at the intersection of Lake Youngs Way S.E. and S.E. 18th Street, approximately 600 feet northwest of the site. A new conveyance system will be constructed within S.E.18th Street in order to provide adequate depth within the on-site detention facility. Upon discharging to the existing storm system at Lake Youngs Way S.E. the existing 18-inch concrete pipe turns south and conveys stormwater to the entrance of Tiffany Park. Our field investigation found that the existing storm pipe turns north and enters the parking lot. At this point we were unable to follow the exact route of the existing storm as the remodel of Tiffany Park Elementary added additional storm utilities within the parking lot. We requested as-builts of the storm within Tiffany Park from the City of Renton but were unable to obtain the information. We were able to obtain as-built information that shows a 60-inch CMP storm pipe runs along the west property line of the school. This 60-inch storm pipe continues along the rear yards of the properties on the west side of Index Court S.E. A review of the City's GIS map shows that the storm system within Lake Youngs Way S.E. ties into the 60-inch trunk line at the southwest corner of the school property. The trunk line runs northerly for approximately 1,100 feet before turning east to Lake Youngs Way S.E., approximately 150 feet west of the intersection with Index Court S.E. The 60-inch trunk line continues to flow in a northerly direction within Lake Youngs Way S.E. for approximately 1,000 feet to the intersection of Royal Hills Drive. The trunk line discharges to the headwaters of Ginger Creek at the southeast corner of this intersection. At this point we are well beyond the quarter mile downstream point from the project. Because the project will be providing Flow Control Duration Standard Matching Forested and there is no evidence of flooding or erosion within the downstream system we do not anticipate any significant impacts due to the project. Please note that SEPA Condition 2 requested that an additional Level 2 Downstream Drainage Analysis was performed, the document can be found in Section 6.1 of this report. TASK 5 MITIGATION OF EXISTING OR POTENTIAL PROBLEMS During the analysis of the downstream system there were no existing problems detected or in need of mitigation. The project will be providing Flow Control Duration Standard Matching Forested Site Conditions and therefore no further mitigation of potential problems will be needed. SITE60-INCHTRUNK LINEDISCHARGETO GINGERCREEK Tab 4.0 16055.016.doc 4.0 FLOW CONTROL AND WATER QUALITY FACILITY ANALYSIS AND DESIGN A. Existing Site Hydrology The site is polygonal in shape and ties into two existing road stubs. The first is located in the northwest corner of the site at the dead-end of S.E. 18th Street. The second road stub is located to the southwest of the site on the southern side of the Cedar River Pipeline at the dead end of 124th Place S.E. This site is undeveloped and is currently zoned R8; with a majority of the site being composed of second-growth forest. The site is comprised four tax parcels (212305-9044, 212305-9051, 212305-9054, and 212305- 9061). The elevations of the site range from 456 to 398. There are five wetlands located on site; three of them are Category 2, with two Category 3. The site is bordered by two pipelines. Along the entire length of the site to the south is the Cedar River Pipeline. Similarly the northeastern boundary of the site is bordered by the Mercer Island Pipeline along its entirety. The western and northern edges of the site are surrounded by single-family homes on medium-sized lots. On-site soils are mapped as mostly Alderwood, and a small portion of Arents. In the undeveloped condition runoff flows off site onto the properties immediately adjacent to the west or onto S.E. 18th Street where it is collected by the existing stormwater conveyance system. Please refer to the pre-developed drainage area map within Section 1.0 for basin area breakdown for land cover areas. Pre-Developed Basin: The Pre-Developed Basin can be broken down as follows: Notes: 1. Ex. R/W upstream = 0.65 Ac Clean rooftops upstream = 0.40 Ac Roof area measured conservatively from aerial photographs 2. Ex Pasture upstream = 1.51 Ac Ex Till Grass upstream = 1.37 Ac Ex Till Forest = 20.79 Ac The Pre-Developed Peak Rates are as follows: 2-year = 0.86 cfs 10-year = 1.47 cfs 100-year =2.47 cfs B. Developed Site Hydrology The completed project will create 94 lots, the total developed area will be 21.66 acres in size. New impervious surfaces will include roadways, driveways, and roof areas. The project will be providing landscaped pervious areas, open space/park areas, and a drainage facility. Impervious Pervious Total Area 1.05 Ac(1) 23.67 Ac(2) 24.72 Ac 16055.016.doc A conveyance system consisting of catch basins and storm pipe will be constructed in the roadways to collect drainage from impervious surfaces and lots and conveyed to the new drainage facility. A detention vault and StormFilter vault will be constructed in Tract A to provide water quality and flow control for the project. The vault will contain a control structure fitted with a riser overflow. Runoff will be conveyed to a proposed 18-inch pipe which will discharge runoff into the existing storm drain conveyance system at the intersection of Lake Youngs Way S.E. and S.E. 18th Street. For further detail please reference the Developed Basin Map in Section 1.0. Please note that in the developed condition that the tributary areas to the on-site wetlands will be altered during construction. In order to maintain their existing hydrological function a portion of the lots along the existing wetlands (Wetland A, Wetland B and Wetland C) will discharge their roof drains into the wetland areas to maintain wetland hydrology. Please reference the Wetland Hydrology Analysis prepared by Ed McCarthy, PE, PS dated October 27, 2016 located in section 6.2 of this report. Runoff from these wetlands will be collected and routed to the on-site drainage facility. Additionally you may reference the Wetland Tributary Area Map and the Developed Wetland Tributary Area Map located within this section of the report. Post Developed Basin: The Post Developed Basin includes the developed basin area tributary to the new drainage facility. Individual Lot BMPs are required per the 2009 KCSWDM and 2010 City of Renton Amendments. Full Infiltration and Full Dispersion are not feasible due to the soil types and limited flow paths available. For purposes of sizing the onsite drainage facility we utilized the Reduced Impervious Surface Credit Individual Lot BMP. The R-8 zone allows for 75 percent max impervious surface per lot. For purposes of sizing the drainage facilities we reduced the allowable impervious coverage to 65 percent. The following list provides a basin area breakdown: Notes: 1. Roads and Sidewalks = 4.29 Ac Lot Area @ 65% impervious = 7.62 Ac Ex. R/W and roof tops upstream = 1.05 Ac 2. Ex Pasture upstream = 1.51 Ac Till Grass = 6.68 Ac Ex Till Forest = 3.33 Ac The Post Developed Peak Release Rates are as follows: 2-year = 0.47 cfs 10-year = 1.23 cfs 100-year = 5.53 cfs Impervious Pervious Total Area 12.96 Ac(1) 11.52 Ac(2) 24.48 Ac 16055.016.doc Bypass Basins: The two bypass basins include small areas along the western portion of S.E. 18th Street and the southern portion of 124th Place S.E. near the boundaries of the site. Due to the existing roadway stubs in relation to the maximum water surface elevation in the vault we are unable to route the runoff to the on-site detention vault. These two areas meet at the same point of convergence located one-quarter mile downstream. In the existing condition the 100-year peak flow rate is less than 0.4 cfs at 0.09cfs. Both bypass basins are 0.12 in size for a total of 0.24 acres of bypass area. Bypass Basin #1 creates 0.09 acres of new impervious surface and Bypass Basin #2 creates 0.10 acres of new impervious surface area. Water quality requirements are not applicable because both areas create less than 5,000 square feet of new impervious surface within each bypass area. In order to meet the compensatory mitigation by a flow control facility the detention facility has been sized to accommodate this bypass area. Both bypass basins are collected by the downstream conveyance systems adjacent to the developed plat. These systems eventually converge at the intersection of S.E. 18th Street and Lake Youngs Way S.E. where they combine with runoff from the developed site and are ultimately conveyed and discharged into Ginger Creek. Combined Bypass peak rates are as follows: Pre-Developed 2-year = 0.05 cfs 10-year = 0.06 cfs 100-year = 0.09 cfs Developed 2-year = 0.05 cfs 10-year = 0.06 cfs 100-year = 0.10 cfs C. Performance Standards The KCRTS Runoff Time Series Program was used to size the detention facility. The detention pond was sized for the Flow Control Duration Standard Matching Forested Site Conditions based on the requirements of the 2009 KCSWDM and the 2010 City of Renton Amendments to the KCSWDM. Individual Lot BMPs are required as well. Full infiltration and Full Dispersion are not feasible due to the soil types and limited flow paths available. For purposes of sizing the onsite drainage facility we utilized the Reduced Impervious Surface Credit Individual Lot BMP. The R-8 zone allows for 75 percent max impervious surface per lot. For purposes of sizing the drainage facilities the allowable impervious coverage was reduced to 65 percent. The detention vault has been designed to provide flow duration control. Please see the attached duration analysis curve chart to see that flow control performance has been met. D. Flow Control System The King County Runoff Time Series (KCRTS) Program was used to size the detention facility. Please refer to the KCRTS computations attached in this section. Based on the detention pond sizing calculations, the pond volume required is 213,296 cubic feet. The pond volume provided is 229,130 cubic feet. Overflow sizing calculations are also provided in this section. The Vault will contain a control structure fitted with a riser overflow. 16055.016.doc Please refer to the drainage facility plan sheets in this section for details E. Water Quality System Basic Water Quality Treatment based on the requirements of the 2009 KCSWDM and 2010 City of Renton Amendments will be fulfilled by a StormFilter located immediately downstream of the control structure using ZPG cartridges. For further detail on the sizing of the StormFilter please refer to the sizing calculations provided by Contech within this section. Please refer to the drainage facility plan sheets in this section for details TRACT A DETENTION VAULT TIME SERIES AND PEAK FLOW RATES LA 3.33 0.00 0.00000 Till Forest 1.51 0.00 0.00000 Till Pasture 6.68 0.00 0.00000 Till Grass 0.00 0.00 0.00000 Outwash Forest 0.00 0.00 0.00000 Outwash Pasture 0.00 0.00 0.00000 Outwash Grass 0.00 0.00 0.00000 Wetland 12.96 0.00 0.00000 Impervious 16055dev.tsf T 1.000000 Flow Frequency Analysis Time Series File:16055dev.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 3.96 6 2/09/01 2:00 7.98 1 100.00 0.990 3.18 8 1/05/02 16:00 4.90 2 25.00 0.960 4.73 3 2/27/03 7:00 4.73 3 10.00 0.900 3.37 7 8/26/04 2:00 4.22 4 5.00 0.800 4.06 5 10/28/04 16:00 4.06 5 3.00 0.667 4.22 4 1/18/06 16:00 3.96 6 2.00 0.500 4.90 2 10/26/06 0:00 3.37 7 1.30 0.231 7.98 1 1/09/08 6:00 3.18 8 1.10 0.091 Computed Peaks 6.95 50.00 0.980 Flow Frequency Analysis Time Series File:16055-dev.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 3.96 6 2/09/01 2:00 7.96 1 100.00 0.990 3.17 8 1/05/02 16:00 4.88 2 25.00 0.960 4.72 3 2/27/03 7:00 4.72 3 10.00 0.900 3.36 7 8/26/04 2:00 4.21 4 5.00 0.800 4.04 5 10/28/04 16:00 4.04 5 3.00 0.667 4.21 4 1/18/06 16:00 3.96 6 2.00 0.500 4.88 2 10/26/06 0:00 3.36 7 1.30 0.231 7.96 1 1/09/08 6:00 3.17 8 1.10 0.091 Computed Peaks 6.93 50.00 0.980 Developed Peak Flows 100yr Peak 10yr Peak 2yr peak Flow Frequency Analysis Time Series File:rdout.tsf Project Location:Sea-Tac ---Annual Peak Flow Rates--- -----Flow Frequency Analysis------- Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) (ft) Period 1.64 2 2/09/01 20:00 5.43 11.40 1 100.00 0.990 0.386 7 12/28/01 18:00 1.64 10.61 2 25.00 0.960 1.21 4 3/06/03 22:00 1.40 9.25 3 10.00 0.900 0.333 8 8/26/04 6:00 1.21 8.34 4 5.00 0.800 0.466 6 1/05/05 17:00 1.18 8.21 5 3.00 0.667 1.18 5 1/18/06 23:00 0.466 6.60 6 2.00 0.500 1.40 3 11/24/06 8:00 0.386 5.19 7 1.30 0.231 5.43 1 1/09/08 10:00 0.333 3.87 8 1.10 0.091 Computed Peaks 4.17 11.30 50.00 0.980 Vault Peak Flow Release Rates 100yr Peak 10yr Peak 2yr peak ALLURA AT TIFFANY PARK ALLURA AT TIFFANY PARKTED-40-39232/27/17 ALLURA AT TIFFANY PARK ALLURA AT TIFFANY PARKTED-40-39232/27/17 ALLURA AT TIFFANY PARK ALLURA AT TIFFANY PARKTED-40-39232/27/17 800-338-1122 513-645-7000 513-645-7993 FAX 9025 Centre Pointe Dr., Suite 400, West Chester, OH 45069 SF0822 STORMFILTER STANDARD DETAILTHIS PRODUCT MAY BE PROTECTED BY ONE OR MORE OF THE FOLLOWING U.S. PATENTS: 5,322,629; 5,524,576; 5,707,527; 5,985,157; 6,027,639; 6,649,048; RELATED FOREIGN PATENTS, OR OTHER PATENTS PENDING. STORMFILTER TREATMENT CAPACITY IS A FUNCTION OF THE CARTRIDGE SELECTION AND THE NUMBER OF CARTRIDGES. THE STANDARD VAULT STYLE IS SHOWN WITH THE MAXIMUM NUMBER OF CARTRIDGES (56). VAULT STYLE OPTIONS INCLUDE INLET BAY (49), INLET BAY/OUTLET BAY (46), OUTLET BAY (51), NLET BAY/FULL HEIGHT BAFFLE WALL (41), FULL HEIGHT BAFFLE WALL (46). STORMFILTER 8X22 PEAK HYDRAULIC CAPACITY IS 1.8 CFS. IF THE SITE CONDITIONS EXCEED 1.8 CFS AN UPSTREAM BYPASS STRUCTURE IS REQUIRED. FOR M AINTENANCE CA L L 1.8 0 0 .3 3 8 .1122 C le a n w a t e r s t ar ts here GENERAL NOTES 1.CONTECH TO PROVIDE ALL MATERIALS UNLESS NOTED OTHERWISE. 2.DIMENSIONS MARKED WITH ( ) ARE REFERENCE DIMENSIONS. ACTUAL DIMENSIONS MAY VARY. 3.FOR SITE SPECIFIC DRAWINGS WITH DETAILED VAULT DIMENSIONS AND WEIGHTS, PLEASE CONTACT YOUR CONTECH ENGINEERED SOLUTIONS LLC REPRESENTATIVE. www.ContechES.com 4.STORMFILTER WATER QUALITY STRUCTURE SHALL BE IN ACCORDANCE WITH ALL DESIGN DATA AND INFORMATION CONTAINED IN THIS DRAWING. 5.STRUCTURE SHALL MEET AASHTO HS20 LOAD RATING, ASSUMING EARTH COVER OF 0' - 5' AND GROUNDWATER ELEVATION AT, OR BELOW, THE OUTLET PIPE INVERT ELEVATION. ENGINEER OF RECORD TO CONFIRM ACTUAL GROUNDWATER ELEVATION. CASTINGS SHALL MEET AASHTO M306 AND BE CAST WITH THE CONTECH LOGO. 6.FILTER CARTRIDGES SHALL BE MEDIA-FILLED, PASSIVE, SIPHON ACTUATED, RADIAL FLOW, AND SELF CLEANING. RADIAL MEDIA DEPTH SHALL BE 7-INCHES. FILTER MEDIA CONTACT TIME SHALL BE AT LEAST 38 SECONDS. 7.SPECIFIC FLOW RATE IS EQUAL TO THE FILTER TREATMENT CAPACITY (gpm) DIVIDED BY THE FILTER CONTACT SURFACE AREA (sq ft). 8.STORMFILTER STRUCTURE SHALL BE PRECAST CONFORMING TO ASTM C-857 AND AASHTO LOAD FACTOR DESIGN METHOD. INSTALLATION NOTES A.ANY SUB-BASE, BACKFILL DEPTH, AND/OR ANTI-FLOTATION PROVISIONS ARE SITE-SPECIFIC DESIGN CONSIDERATIONS AND SHALL BE SPECIFIED BY ENGINEER OF RECORD. B.CONTRACTOR TO PROVIDE EQUIPMENT WITH SUFFICIENT LIFTING AND REACH CAPACITY TO LIFT AND SET THE STORMFILTER VAULT (LIFTING CLUTCHES PROVIDED). C.CONTRACTOR TO INSTALL JOINT SEALANT BETWEEN ALL VAULT SECTIONS AND ASSEMBLE VAULT. D.CONTRACTOR TO PROVIDE, INSTALL, AND GROUT PIPES. MATCH OUTLET PIPE INVERT WITH OUTLET BAY FLOOR. E.CONTRACTOR TO TAKE APPROPRIATE MEASURES TO PROTECT CARTRIDGES FROM CONSTRUCTION-RELATED EROSION RUNOFF. STORMFILTER DESIGN NOTES CARTRIDGE HEIGHT SPECIFIC FLOW RATE (gpm/sf) CARTRIDGE FLOW RATE (gpm) RECOMMENDED HYDRAULIC DROP (H) 27"18"LOW DROP 3.05'2.3'1.8' CARTRIDGE SELECTION 18.79 12.53 8.35 2 gpm/sf 22.5 11.25 15 10 57.5 1.67* gpm/sf 1 gpm/sf 2 gpm/sf 1.67* gpm/sf 1 gpm/sf 2 gpm/sf 1.67* gpm/sf 1 gpm/sf * 1.67 gpm/sf SPECIFIC FLOW RATE IS APPROVED WITH PHOSPHOSORB® (PSORB) MEDIA ONLY HYDRAULIC DROP(H) INLET INV.TO OUTLET INV.INSIDE VAULT HEIGHT6' TYPICALSECTION A-A OUTLET PIPE OVERFLOW ASSEMBLY GRADE RING/RISERS INLET DISSIPATOR INLET PIPE CONTRACTOR TO GROUT TO FINISHED GRADE STORMFILTER CARTRIDGE FLOW KIT STEP OUTLETINLET PLAN VIEW VAULT STYLE: OUTLET SUMP (NIB) INLET DISSIPATOR (9'-3") OUTLET SUMP 2'-0"A A (2'-0") STORMFILTER CARTRIDGE 22'-0"8'-0"ALTERNATE PIPE LOCATION (TYP) 6" CONCRETE WALL WIDTH MAY VARY REGIONALLY ** STRUCTURE ID WATER QUALITY FLOW RATE (cfs) PEAK FLOW RATE (cfs) RETURN PERIOD OF PEAK FLOW (yrs) NUMBER OF CARTRIDGES REQUIRED MEDIA TYPE (PERLITE, ZPG, PSORB) PIPE DATA:I.E.MATERIAL DIAMETER INLET PIPE #1 INLET PIPE #2 OUTLET PIPE SITE SPECIFIC DATA REQUIREMENTS WIDTH HEIGHTANTI-FLOTATION BALLAST NOTES/SPECIAL REQUIREMENTS: DOWNSTREAM RIM ELEVATION CARTRIDGE FLOW RATE (gpm/f) * PER ENGINEER OF RECORD CARTRIDGE HEIGHT (27", 18", LOW DROP(LD)) UPSTREAM RIM ELEVATION ** 402.5 18"CPEP384.60 18"CPEP386.90 ZPG 1.00 53 100 5.53 0.47 SF#1 18" 402.5 ALLURA AT TIFFANY PARK ALLURA AT TIFFANY PARKTED-40-39232/27/17 ALLURA AT TIFFANY PARK ALLURA AT TIFFANY PARKTED-40-39232/27/17 Tab 5.0 16055.016.doc 5.0 CONVEYANCE SYSTEM ANALYSIS AND DESIGN The on-site conveyance system was designed in accordance with the 2009 KCSWDM and the 2010 City of Renton Amendments to the KCSWDM. The proposed conveyance system for this project is curb, gutter, catch basins, and storm drainage pipe. The majority of the storm drainage pipe used will consist of smooth-walled line corrugated polyethylene pipe with a Manning's roughness coefficient design value of 0.014. 100-year conveyance calculations for the pipes have been completed using the Rational Method as shown on the enclosed Excel spreadsheet. The following are the parameters used in design of the pipes: 1. A Runoff Coefficient – 'C' value was calculated from the 2009 KCSWDM for each tributary area pursuant to table 3.2.1.A. 2. A 100-year/24-hour precipitation of 3.9 inches in accordance with Figure 3.2.1D. 3. A starting time of concentration of 6.3. 4. An "n" factor of 0.014 (0.012 for Backwater Analysis) The tributary areas have been calculated to each of the catch basins connecting to the proposed piping system, as shown on the enclosed map. A 100-year backwater analysis to determine the hydraulic grade line and to see if any catch basin rims overtop has also been performed using KCBW in accordance with the 2009 KCSWDM and the 2010 City of Renton Amendments to the KCSWDM. Please see the attached calculations in this section. Tab 6.0 16055.016.doc 6.0 SPECIAL REPORTS AND STUDIES The following special reports have been prepared and have been submitted under separate cover. 6.1 Reserve at Tiffany Park - Hydraulic Assessment for Offsite Storm System prepared by Ed McCarthy, PE, PS dated February 24, 2017 6.2 Allura at Tiffany Park - Wetland Hydrology Analysis prepared by Ed McCarthy, PE, PS dated October 27, 2016 6.3 Revised Tree Protection Plan - Reserve at Tiffany Park prepared by Washington Forestry Consultants dated October 4, 2016 6.4 Geotechnical Engineering Study Allura at Tiffany Park prepared by Earth Solutions NW, LLC dated November 11, 2016 Reserve at Tiffany Park - Hydraulic Assessment for Offsite Storm System, prepared by Ed McCarthy, PE, PS dated February 24, 2017 6.1 Technical Memorandum Re: The Reserve at Tiffany Park – Hydraulic Assessment for Offsite Storm System Project: LUA13-001572 Project Location: Renton, WA Prepared by: Ed McCarthy, PE, PS 9957 171st Ave SE Renton, WA 98059 Prepared for: Barghausen Consulting Engineers 18215 72nd Avenue South Kent, WA 98032 Date: Revised 2-24-17 1 Background Information This report documents the results of a Level 2 (King County Department of Natural Resources, 2009) hydraulic assessment that I conducted for the existing storm system within the Tiffany Park area of Renton, Washington (Figure 1). The storm system evaluated extends from the discharge connection location for the proposed Reserve at Tiffany Park plat to the pipe network’s outfall at the headwater of Ginger Creek. The Reserve at Tiffany Park plat is a proposed residential project with 98 lots on 20.79 acres. Stormwater from the developed site will be collected onsite and detained in a stormwater vault designed to Level 2 Flow Control standards. Stormwater from the vault will be discharged to a new 18-inch diameter conveyance pipe that will convey flows from the west side of the development, down SE 18th Street, to the intersection of Lake Young Way SE. The new pipe system will connect to an existing storm pipe that flows in a southwest direction along Lake Young Way SE. The existing pipe system is also 18-inch diameter until it merges with a 60- inch diameter trunkline about 600 feet downstream from the connection point. The trunkline collects runoff from contributing tributary pipe systems and ultimately discharges to Ginger Creek. Stormwater from the Reserve at Tiffany Park currently discharges to the Ginger Creek conveyance system but flows to the network in a dispersed manner. Method of Analysis A backwater analysis was conducted to evaluate the hydraulic grade line in the downstream pipe system for the predicted 25-year storm. The reach of storm pipe extending from Ginger Creek to the intersection of Lake Young Way SE and SE 18th Street was evaluated. Catchment areas that drain to the pipe network were delineated based on the following resources:  City of Renton storm system map  Aerial topography with 2-foot contour intervals  Cedar River Basin Plan catchment boundaries 2 Each of the catchments represents a tributary pipe network that collects runoff from surrounding development. The pipe network was modeled with the Reserve at Tiffany Park in its proposed developed condition. Pipe materials, pipe lengths, pipe invert elevations, and catch basin rim elevations for the pipe system, were based on the as-built engineering plans for Tiffany Park No. 2 (Group Four, Inc. March 16, 1979), storm inventory data from the City’s GIS database, and field measurements. Flow inputs to the pipe network were predicted using KCRTS with a 15-minute time step. Residential development is the primary land use in the basin. A total of 52 percent effective impervious area was assumed in calculating cover types for this land use. The flow contribution to the pipe network from the Reserve at Tiffany Park was based on the predicted 25-year outflow rate from the proposed stormwater vault for developed conditions (Barghausen Consulting Engineers, February 20, 2017). A small amount of bypass from the proposed development also discharges to the downstream pipe network, which was also included in the analysis. A custom spreadsheet based on formulas presented in King County’s Surface Water Design Manual was used to perform the hydraulic backwater calculations. The downstream boundary condition assumed normal flow conditions at the pipe outfall in Ginger Creek. The 60-inch diameter pipe reach is CMP and was modeled with a roughness coefficient of 0.024. The existing 18-inch diameter pipe reach is concrete pipe and was modeled with a roughness coefficient of 0.012. Modeling Results Soils in the basin are predominately of the Alderwood and Arents series, both of which are considered till soils (Figure 2). A total area of 220.52 acres contributes to the pipe network (Table A.1, Figure 3). The pipe network basin was broken down into eight catchments, each representing a tributary input to the downstream pipe trunkline (Figure 3). A flow network diagram for the conveyance system, showing inflow locations of each catchment, is provided in Figure A.1. A summary of the contributing areas and their associated cover types is provided in Table A.1. The 25-year peak flow rates for each of the catchments are also shown in Table A.1. KCRTS documentation used in calculating the flow rates for each of the contributing catchments is provided in Appendix B, as are the predicted outflow rates from the stormwater vault for the Reserve at Tiffany Park. The KCRTS design for the proposed stormwater vault is also provided in Appendix B. The King County Surface Water Design Manual (KCSWDM) (King County Department of Natural Resources, 2009) requires that existing downstream conveyance systems have sufficient capacity to convey and contain at least the predicted 25-year peak flow rate assuming developed 3 conditions for tributary areas. The KCSWDM also requires that the 100-year peak rate to the pipe system does not aggravate a severe flooding1 or severe erosion problem. Backwater calculations demonstrate that basin flows, including the discharge from the Reserve at Tiffany Park, are conveyed in the pipe network with no overflow predicted for up to the 25- year storm. Backwater results are provided in Table A.2 for the pipe network with discharge from the Reserve at Tiffany Park under proposed developed conditions. The contributing 25- year peak flow rate from the Reserve at Tiffany Park site to the storm system was predicted to only slightly increase under proposed developed conditions. Under proposed developed conditions the 25-year peak rate from the stormwater vault and bypass area was predicted to be 1.71 cubic feet per second versus 1.35 cubic feet per second under forested conditions (Table A.1 and Appendix B). Stormwater is predicted to surge from the trunkline at various catch basin locations for the 100- year peak rate for both existing and proposed developed conditions. The upper reach of the trunkline is located between Tiffany Park Elementary school and adjacent residential lots. The lower reach of the trunkline is along roadway. While city staff cites instances of past nuisance flooding along the trunkline, no documentation of severe flooding is on the record. Presumably, if severe flooding is a potential outcome of large storms, it likely would have occurred over the past 36 years since the system was installed. The existing 100-year predicted flow to the system is 165 cubic feet per second. Contributions from the proposed Reserve at Tiffany Park would increase the 100-year rate by less than 1 percent, to 166 cubic feet per second. This relatively small increase in flow would not noticeably aggravate the extent of flooding that has the potential to occur. If you have questions regarding my assessment or conclusions, or need additional information, please contact me. 1 Severe flooding is when there is flooding across all lanes of a roadway or a sole access driveway or there is flooding of the finished floor area of a habitable building (King County Department of Natural Resources, 2009). 4 Sincerely, Edward J. McCarthy, Ph.D., P.E. 5 References Barghausen Consulting Engineers, February 20, 2017. Tiffany Park Stormwater Vault Calculations. Kent, Wash. Barghausen Consulting Engineers, February 24, 2014. Preliminary Technical Information Report. Reserve at Tiffany Park, SE 18th Street and 124th Place SE, Renton, Washington. Kent, Wash. Group Four, Inc. March 16, 1979. As-Built Plans – Tiffany Park No. 2 – Sheets 6, 8, and 11 of 13. Lynnwood, Wash. King County Department of Natural Resources, 2009. King County Surface Water Design Manual. Seattle. King County Department of Public Works, Surface Water Management Division, November 1993. Cedar River Current and Future Conditions Report. Seattle. U.S. Department of Agriculture, Soil Conservation Service, 1973. Soil Survey of King County Area, Washington. Seattle. 9 Appendix A. Catchment Areas and Backwater Analysis Table A.1. Catchment Cover Types and Flow Rates – Proposed Conditions Catchment Land Use Forest Landscape Impervious Total 25-year Flow Rate (AC) (AC) (AC) (AC) (CFS) C10 Residential 5.23 5.67 10.90 6.25 C20 Residential 7.04 7.62 14.66 10.10 Park/Utility 5.26 0.58 5.84 C20 Subtotal 12.29 8.21 20.50 C30 Residential 7.97 8.63 16.60 13.91 School 5.34 3.56 8.90 C30 Subtotal 13.31 12.19 25.50 C40 Residential 13.68 14.82 28.50 16.36 C50 Residential 43.71 47.35 91.06 53.70 Park 4.05 0.45 4.50 Open Space 4.34 4.34 C50 Subtotal 4.34 47.76 47.80 99.90 C60 Residential 5.04 5.46 10.50 6.02 C70 Residential 3.33 5.36 12.10 20.79 1.71 C80 Residential 2.88 1.05 3.93 Total 7.67 105.55 107.30 220.52 108.05 Notes: 1. Residential Land Use: 52% impervious area assumed. 2. Cover types for Catchment C70 are based on proposed site plan. 3. Catchment C80 flows to the proposed stormwater vault. 4. Predicted outflow rates from Catchments C70 and C80 used in hydraulic assessment are those predicted to discharge from the proposed Tiffany Park stormwater vault plus bypass areas. Figure A.1. Developed Conditions - Routing DiagramDATE2/20/17PAGETITLEContributing BasinLegendStorm PipeCB1Catch Basin IDR/DStormwater DetentionQ25(CFS)CB4CB5CB6CB9BYPASSCB10CB11C1060"60"CB8Proposed 18" Pipe77.7977.797.737.73Dia.R/DC70C800.0718"18"18"CB1CB260" 60"CB3108.05 101.80Ginger Creek60" 60"60"C40C50C607.73CB760"1.646.02101.80 101.80 91.7077.7970.0610.106.25C20C3013.91Reserve at Tiffany Park Table C1-1 2-24-17 NAVD88Project: Tiffany ParkTable A.2. Backwater Analysis for Offsite Conveyance SystemDate: 02/24/17Ginger Creek to Proposed Plat Connection - 25-Year1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 15a 16 17 18 19 20 Pipe Barrel Barrel Barrel Friction Entrance Entrance Entrance Exit Exit Outlet Inlet Inlet Approach Bend Bend Bend Junctions HW TopPipe Segment Q Length Size "n" Outlet Elev Inlet Elev Area Velocity Vel Head TW Elev Loss HGL Elev HL HL HL HL Cntrl. Elev Control Cntrl. Elev Vel. Head Defl. HL HL Added Q Kl HL Elev. UpstreamCB to CB (cfs) (ft) (in) Value (ft) (ft) (sf) (fps) (ft) (ft) (ft) (ft) Coef (ft) Coef (ft) (ft) HW/D (ft) (ft) (deg) Coef (ft) Q3 (ft) (ft) StructureGinger Cr. 1 108.05 48 60 0.024 353.56 353.7019.635 5.50 0.47355.600.28 355.880.500.241.000.47 356.590.90358.20 0.4200.020.016.250.05 0.02 357.81367.601 2 101.80 320 60 0.024 353.70 354.6619.635 5.18 0.42 357.81 1.66 359.470.500.211.000.42 360.100.86358.96 0.4200.020.010.000.00 0.00 359.69367.102 3 101.80 76 60 0.024 354.66 354.8919.635 5.18 0.42 359.69 0.39 360.080.500.211.000.42 360.710.86359.19 0.4200.020.010.000.00 0.00 360.30366.603 4 101.80 254 60 0.024 354.89 355.6519.635 5.18 0.42 360.30 1.32 361.610.500.211.000.42 362.240.86359.95 0.3400.020.0110.100.08 0.03 361.94365.604 5 91.70 150 60 0.024 355.65 356.1019.635 4.67 0.34 361.94 0.63 362.570.500.171.000.34 363.070.80360.10 0.24901.320.3213.910.12 0.03 363.18365.975 6 77.79 149 60 0.024 356.10 356.6519.635 3.96 0.24 363.18 0.45 363.630.500.121.000.24 364.000.75360.40 0.2400.020.000.000.00 0.00 363.76365.076 7 77.79 454 60 0.024 356.65 357.2919.635 3.96 0.24 363.76 1.37 365.130.500.121.000.24 365.500.75361.04 0.2400.020.000.000.00 0.00 365.26366.297 8 77.79 664 60 0.024 357.29 358.6319.635 3.96 0.24 365.26 2.01 367.270.500.121.000.24 367.640.75362.38 0.3000.020.0170.060.52 0.15 367.50370.568 9 7.73 97 18 0.012 361.08 367.191.767 4.37 0.30 367.50 0.44 367.940.500.151.000.30 368.391.18368.96 0.30901.320.390.000.00 0.00 369.06373.799 10 7.73 174 18 0.012 367.75 371.081.767 4.37 0.30 369.06 0.80 369.850.500.151.000.30 370.301.18372.85 0.30901.320.390.000.00 0.00 372.95377.3810 11 7.73 322 18 0.012 371.11 380.211.767 4.37 0.30 372.95 1.47 374.420.500.151.000.30 374.861.18381.98 0.0600.020.007.730.55 0.03 381.95387.600.000 2.00 0.06NOTES: 1. Pipe materials include CMP, concrete and LCPE.2. Flow rates based on KCRTS 15-minute times series for pipe downstream from pond.3. Entrance loss coefficients are from Table 4.3.1.B for LCPE pipe, headwall with square edge entrance.4. Exit loss coefficients are based on Figure 4.2.1.I, Column (14) and ASCE Manual "Design and Construction of Sanitary and Storm Sewers". 1970, page 107.5. Data source: CB11 to CB8 - field survey, CB5 to CB8 - Group Four as-built, Ginger Creek to CB5 - City GIS.6. Vertical datum: NAVD 88.7. Column 15a - Inlet Control HW/D ratio based on nomographs in Fig. 4.3.1.B and Fig. 4.3.1.C of the 2009 King County Surface Water Design Manual.Tiffany Offsite HGL v2.xlsmPage 12/20/20179:12 PM 12 Appendix B. KCRTS Inputs Proposed Vault Design KCRTS Basins KCRTS Command ------------- CREATE a new Time Series ------------------------ Production of Runoff Time Series Project Location : Sea-Tac Computing Series : c10.tsf Regional Scale Factor : 1.00 Data Type : Reduced Creating 15-minute Time Series File Loading Time Series File:C:\KC_SWDM\KC_DATA\STTG15R.rnf : Till Grass 5.23 acres Loading Time Series File:C:\KC_SWDM\KC_DATA\STEI15R.rnf : Impervious 5.67 acres -------------- Total Area : 10.90 acres Peak Discharge: 9.33 CFS at 6:30 on Jan 9 in Year 8 Storing Time Series File:c10.tsf : Time Series Computed KCRTS Command ------------- Enter the Analysis TOOLS Module ------------------------------- Analysis Tools Command ---------------------- Compute PEAKS and Flow Frequencies ---------------------------------- Loading Stage/Discharge curve:c10.tsf : 13 Flow Frequency Analysis -------------------------------------------------------- Time Series File:c10.tsf Project Location:Sea-Tac Frequencies & Peaks saved to File:c10.pks : Analysis Tools Command ---------------------- RETURN to Previous Menu ----------------------- KCRTS Command ------------- CREATE a new Time Series ------------------------ Production of Runoff Time Series Project Location : Sea-Tac Computing Series : c20.tsf Regional Scale Factor : 1.00 Data Type : Reduced Creating 15-minute Time Series File Loading Time Series File:C:\KC_SWDM\KC_DATA\STTG15R.rnf : Till Grass 12.29 acres Loading Time Series File:C:\KC_SWDM\KC_DATA\STEI15R.rnf : Impervious 8.21 acres -------------- Total Area : 20.50 acres Peak Discharge: 15.89 CFS at 6:30 on Jan 9 in Year 8 Storing Time Series File:c20.tsf : Time Series Computed KCRTS Command ------------- Enter the Analysis TOOLS Module ------------------------------- Analysis Tools Command ---------------------- Compute PEAKS and Flow Frequencies ---------------------------------- Loading Stage/Discharge curve:c20.tsf : Flow Frequency Analysis -------------------------------------------------------- Time Series File:c20.tsf Project Location:Sea-Tac Frequencies & Peaks saved to File:c20.pks : Analysis Tools Command ---------------------- RETURN to Previous Menu ----------------------- KCRTS Command ------------- CREATE a new Time Series ------------------------ Production of Runoff Time Series 14 Project Location : Sea-Tac Computing Series : c30.tsf Regional Scale Factor : 1.00 Data Type : Reduced Creating 15-minute Time Series File Loading Time Series File:C:\KC_SWDM\KC_DATA\STTG15R.rnf : Till Grass 13.31 acres Loading Time Series File:C:\KC_SWDM\KC_DATA\STEI15R.rnf : Impervious 12.19 acres -------------- Total Area : 25.50 acres Peak Discharge: 21.10 CFS at 6:30 on Jan 9 in Year 8 Storing Time Series File:c30.tsf : Time Series Computed KCRTS Command ------------- Enter the Analysis TOOLS Module ------------------------------- Analysis Tools Command ---------------------- Compute PEAKS and Flow Frequencies ---------------------------------- Loading Stage/Discharge curve:c30.tsf : Flow Frequency Analysis -------------------------------------------------------- Time Series File:c30.tsf Project Location:Sea-Tac Frequencies & Peaks saved to File:c30.pks : Analysis Tools Command ---------------------- RETURN to Previous Menu ----------------------- KCRTS Command ------------- CREATE a new Time Series ------------------------ Production of Runoff Time Series Project Location : Sea-Tac Computing Series : c40.tsf Regional Scale Factor : 1.00 Data Type : Reduced Creating 15-minute Time Series File Loading Time Series File:C:\KC_SWDM\KC_DATA\STTG15R.rnf : Till Grass 13.68 acres Loading Time Series File:C:\KC_SWDM\KC_DATA\STEI15R.rnf : Impervious 14.82 acres -------------- Total Area : 28.50 acres Peak Discharge: 24.39 CFS at 6:30 on Jan 9 in Year 8 Storing Time Series File:c40.tsf : Time Series Computed KCRTS Command 15 ------------- Enter the Analysis TOOLS Module ------------------------------- Analysis Tools Command ---------------------- Compute PEAKS and Flow Frequencies ---------------------------------- Loading Stage/Discharge curve:c40.tsf : Flow Frequency Analysis -------------------------------------------------------- Time Series File:c40.tsf Project Location:Sea-Tac Frequencies & Peaks saved to File:c40.pks : Analysis Tools Command ---------------------- RETURN to Previous Menu ----------------------- KCRTS Command ------------- CREATE a new Time Series ------------------------ Production of Runoff Time Series Project Location : Sea-Tac Computing Series : c50.tsf Regional Scale Factor : 1.00 Data Type : Reduced Creating 15-minute Time Series File Loading Time Series File:C:\KC_SWDM\KC_DATA\STTF15R.rnf : Till Forest 4.34 acres Loading Time Series File:C:\KC_SWDM\KC_DATA\STTG15R.rnf : Till Grass 47.76 acres Loading Time Series File:C:\KC_SWDM\KC_DATA\STEI15R.rnf : Impervious 47.80 acres -------------- Total Area : 99.90 acres Peak Discharge: 80.84 CFS at 6:30 on Jan 9 in Year 8 Storing Time Series File:c50.tsf : Time Series Computed KCRTS Command ------------- Enter the Analysis TOOLS Module ------------------------------- Analysis Tools Command ---------------------- Compute PEAKS and Flow Frequencies ---------------------------------- Loading Stage/Discharge curve:c50.tsf : Flow Frequency Analysis -------------------------------------------------------- Time Series File:c50.tsf Project Location:Sea-Tac Frequencies & Peaks saved to File:c50.pks : 16 Analysis Tools Command ---------------------- RETURN to Previous Menu ----------------------- KCRTS Command ------------- CREATE a new Time Series ------------------------ Production of Runoff Time Series Project Location : Sea-Tac Computing Series : c60.tsf Regional Scale Factor : 1.00 Data Type : Reduced Creating 15-minute Time Series File Loading Time Series File:C:\KC_SWDM\KC_DATA\STTG15R.rnf : Till Grass 5.04 acres Loading Time Series File:C:\KC_SWDM\KC_DATA\STEI15R.rnf : Impervious 5.46 acres -------------- Total Area : 10.50 acres Peak Discharge: 8.99 CFS at 6:30 on Jan 9 in Year 8 Storing Time Series File:c60.tsf : Time Series Computed KCRTS Command ------------- Enter the Analysis TOOLS Module ------------------------------- Analysis Tools Command ---------------------- Compute PEAKS and Flow Frequencies ---------------------------------- Loading Stage/Discharge curve:c60.tsf : Flow Frequency Analysis -------------------------------------------------------- Time Series File:c60.tsf Project Location:Sea-Tac Frequencies & Peaks saved to File:c60.pks : Analysis Tools Command ---------------------- RETURN to Previous Menu ----------------------- KCRTS Command ------------- CREATE a new Time Series ------------------------ Production of Runoff Time Series Project Location : Sea-Tac Computing Series : c70.tsf Regional Scale Factor : 1.00 Data Type : Reduced Creating 15-minute Time Series File 17 Loading Time Series File:C:\KC_SWDM\KC_DATA\STTF15R.rnf : Till Forest 20.79 acres -------------- Total Area : 20.79 acres Peak Discharge: 2.28 CFS at 9:30 on Jan 9 in Year 8 Storing Time Series File:c70.tsf : Time Series Computed KCRTS Command ------------- Enter the Analysis TOOLS Module ------------------------------- Analysis Tools Command ---------------------- Compute PEAKS and Flow Frequencies ---------------------------------- Loading Stage/Discharge curve:c70.tsf : Flow Frequency Analysis -------------------------------------------------------- Time Series File:c70.tsf Project Location:Sea-Tac Frequencies & Peaks saved to File:c70.pks : Analysis Tools Command ---------------------- RETURN to Previous Menu ----------------------- KCRTS Command ------------- CREATE a new Time Series ------------------------ Production of Runoff Time Series Project Location : Sea-Tac Computing Series : c80.tsf Regional Scale Factor : 1.00 Data Type : Reduced Creating 15-minute Time Series File Loading Time Series File:C:\KC_SWDM\KC_DATA\STTP15R.rnf : Till Pasture 1.51 acres Loading Time Series File:C:\KC_SWDM\KC_DATA\STTG15R.rnf : Till Grass 1.37 acres Loading Time Series File:C:\KC_SWDM\KC_DATA\STEI15R.rnf : Impervious 1.05 acres -------------- Total Area : 3.93 acres Peak Discharge: 2.24 CFS at 6:30 on Jan 9 in Year 8 Storing Time Series File:c80.tsf : Time Series Computed KCRTS Command ------------- Enter the Analysis TOOLS Module ------------------------------- Analysis Tools Command 18 ---------------------- Compute PEAKS and Flow Frequencies ---------------------------------- Loading Stage/Discharge curve:c80.tsf : Flow Frequency Analysis -------------------------------------------------------- Time Series File:c80.tsf Project Location:Sea-Tac Frequencies & Peaks saved to File:c80.pks : Analysis Tools Command ---------------------- RETURN to Previous Menu ----------------------- KCRTS Command ------------- eXit KCRTS Program ------------------ 19 KCRTS 15-Minute Peak Flow Rates Flow Frequency Analysis Time Series File:c10.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 2.70 6 8/27/01 18:00 9.33 1 100.00 0.990 2.02 8 1/05/02 15:00 6.25 2 25.00 0.960 6.25 2 12/08/02 17:15 3.95 3 10.00 0.900 2.17 7 8/23/04 14:30 3.83 4 5.00 0.800 3.95 3 11/17/04 5:00 3.36 5 3.00 0.667 3.36 5 10/27/05 10:45 2.70 6 2.00 0.500 3.83 4 10/25/06 22:45 2.17 7 1.30 0.231 9.33 1 1/09/08 6:30 2.02 8 1.10 0.091 Computed Peaks 8.30 50.00 0.980 Flow Frequency Analysis Time Series File:c20.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 3.94 6 10/08/00 4:15 15.89 1 100.00 0.990 3.15 8 1/05/02 15:00 10.10 2 25.00 0.960 10.10 2 12/08/02 17:15 7.20 3 10.00 0.900 3.18 7 8/26/04 0:45 5.71 4 5.00 0.800 7.20 3 11/17/04 5:00 5.18 5 3.00 0.667 5.18 5 10/27/05 10:45 3.94 6 2.00 0.500 5.71 4 10/25/06 22:45 3.18 7 1.30 0.231 15.89 1 1/09/08 6:30 3.15 8 1.10 0.091 Computed Peaks 13.96 50.00 0.980 Flow Frequency Analysis Time Series File:c30.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 5.81 6 8/27/01 18:00 21.11 1 100.00 0.990 4.44 8 1/05/02 15:00 13.91 2 25.00 0.960 13.91 2 12/08/02 17:15 9.14 3 10.00 0.900 4.68 7 8/23/04 14:30 8.31 4 5.00 0.800 9.14 3 11/17/04 5:00 7.37 5 3.00 0.667 7.37 5 10/27/05 10:45 5.81 6 2.00 0.500 8.31 4 10/25/06 22:45 4.68 7 1.30 0.231 21.11 1 1/09/08 6:30 4.44 8 1.10 0.091 Computed Peaks 18.71 50.00 0.980 20 Flow Frequency Analysis Time Series File:c40.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 7.06 6 8/27/01 18:00 24.39 1 100.00 0.990 5.27 8 1/05/02 15:00 16.36 2 25.00 0.960 16.36 2 12/08/02 17:15 10.34 3 10.00 0.900 5.68 7 8/23/04 14:30 10.01 4 5.00 0.800 10.34 3 11/17/04 5:00 8.79 5 3.00 0.667 8.79 5 10/27/05 10:45 7.06 6 2.00 0.500 10.01 4 10/25/06 22:45 5.68 7 1.30 0.231 24.39 1 1/09/08 6:30 5.27 8 1.10 0.091 Computed Peaks 21.72 50.00 0.980 Flow Frequency Analysis Time Series File:c50.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 22.77 6 8/27/01 18:00 80.86 1 100.00 0.990 17.26 8 1/05/02 15:00 53.70 2 25.00 0.960 53.70 2 12/08/02 17:15 34.47 3 10.00 0.900 18.35 7 8/23/04 14:30 32.46 4 5.00 0.800 34.47 3 11/17/04 5:00 28.59 5 3.00 0.667 28.59 5 10/27/05 10:45 22.77 6 2.00 0.500 32.46 4 10/25/06 22:45 18.35 7 1.30 0.231 80.86 1 1/09/08 6:30 17.26 8 1.10 0.091 Computed Peaks 71.80 50.00 0.980 Flow Frequency Analysis Time Series File:c60.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 2.60 6 8/27/01 18:00 8.99 1 100.00 0.990 1.94 8 1/05/02 15:00 6.02 2 25.00 0.960 6.02 2 12/08/02 17:15 3.80 3 10.00 0.900 2.10 7 8/23/04 14:30 3.69 4 5.00 0.800 3.80 3 11/17/04 5:00 3.24 5 3.00 0.667 3.24 5 10/27/05 10:45 2.60 6 2.00 0.500 3.69 4 10/25/06 22:45 2.10 7 1.30 0.231 8.99 1 1/09/08 6:30 1.94 8 1.10 0.091 Computed Peaks 8.00 50.00 0.980 21 Flow Frequency Analysis Time Series File: c70.tsf – subject site – forested conditions Project Location:Sea-Tac ---Annual Peak Flow Rates--- -----Flow Frequency Analysis------- Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 1.35 2 2/09/01 17:15 2.28 1 100.00 0.990 0.404 7 1/06/02 2:30 1.35 2 25.00 0.960 0.963 4 3/06/03 18:45 1.04 3 10.00 0.900 0.049 8 3/08/04 18:45 0.963 4 5.00 0.800 0.644 6 1/05/05 7:30 0.887 5 3.00 0.667 1.04 3 1/18/06 20:00 0.644 6 2.00 0.500 0.887 5 11/24/06 5:15 0.404 7 1.30 0.231 2.28 1 1/09/08 9:30 0.049 8 1.10 0.091 Computed Peaks 1.97 50.00 0.980 Flow Frequency Analysis Time Series File:c80.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 0.581 6 2/09/01 12:30 2.24 1 100.00 0.990 0.429 7 1/05/02 15:00 1.43 2 25.00 0.960 1.43 2 12/08/02 17:15 0.889 3 10.00 0.900 0.411 8 8/26/04 0:45 0.728 4 5.00 0.800 0.889 3 11/17/04 5:00 0.681 5 3.00 0.667 0.681 5 10/27/05 10:45 0.581 6 2.00 0.500 0.728 4 10/25/06 22:45 0.429 7 1.30 0.231 2.24 1 1/09/08 6:30 0.411 8 1.10 0.091 Computed Peaks 1.97 50.00 0.980 KCRTS Stormwater Design and Outflow Rates for the Reserve at Tiffany Park Vault 22 Allura at Tiffany Park - Wetland Hydrology Analysis prepared by Ed McCarthy, PE, PS dated October 27, 2016 6.2 ED MCCARTHY, P.E., PS Hydrology ▪ Hydraulics ▪ Engineering 9957 171 AVENUE SE RENTON, WA 98059 (425) 271-5734 October 27, 2016 Mr. Barry Talkington Barghausen Consulting Engineers, Inc. 18215 72nd Ave South Kent, WA 98032 Re: Allura at Tiffany Park– Wetland Hydrology Analysis Renton, Washington Dear Mr. Talkington: At your request I’ve conducted a hydrologic analysis of wetlands that are located at the Allura at Tiffany Park site (Figure 1). The wetlands that I evaluated are identified as Wetland A and Wetlands B/C within the proposed plat. I used the hydrologic model KCRTS to compare predevelopment hydrology in the wetlands to that predicted to occur after the proposed Allura at Tiffany Park project has been completed. Other wetlands on the site include Wetlands D and E, which are not affected by the proposed project, and therefore were not evaluated. Allura at Tiffany Park The Allura at Tiffany Park site is located at the end of SE 18th Street in the Tiffany Park area of Renton, Washington. Wetland A is located in the northwest portion of the site. Wetlands B/C are located in the southeast portion of the site. None of the wetlands have a well-defined outlet, but each is within the basin that drains to Ginger Creek (Barghausen Consulting Engineers, February 24, 2014). The proposal for development includes constructing a single-family residential plat with road, utility and drainage improvements. Runoff collected from the developed area will be conveyed to a stormwater vault located in the west portion of the site (Barghausen Consulting Engineers, November 15, 2016) and subsequently discharged to a pipe system that discharges to Ginger Creek. Each of the wetlands evaluated is a forested depression type wetland. Wetlands A and C have a Category 2 rating. Wetland B has a Category 3 rating (Schulz, June 3, 2014). Photos of the wetlands are provided in Attachment C. Method of Analysis A hydrologic assessment of contributing basins was conducted to characterize flow regimes to the wetlands. The basin areas draining to the wetlands under existing conditions were delineated using the project’s topographic map having 2-foot contour intervals (Figure 2). The basin for Wetland A is mostly onsite with a portion of the basin extending into the right-of-way along the north property line. Mr. Barry Talkington Page 2 October 27, 2016 Wetlands B and C are adjacent to each other and their hydrology can be assessed by evaluating a single basin. The basin for Wetlands B/C is also mostly onsite, but a significant portion of the basin extends offsite, to the north. The basin areas draining to the wetlands under proposed developed conditions were calculated based on the drainage plan for the project (Figure 3). The areas of the basins were broken down into categories of land cover type and hydrologic soil group. Categories of land cover types included forest, pasture, landscape and impervious. These areas were delineated using a color aerial photograph from King County Water and Land Resource Department (KCWLRD, 2005). Hydrologic soil groups included Group C/D, being poorly drained soil with a relatively high amount of surface runoff. The hydrologic soil groups were based on those pre-designated to mapped soils series (SCS, 1973). The hydrology of the wetlands was evaluated for two scenarios including i) existing basin conditions and ii) proposed developed basin conditions. Hydrology data for the wetlands’ basins were input to the King County Runoff Time Series v6.00 (KCRTS) hydrologic model. KCRTS is a continuous hydrologic model that develops runoff time series for a 50-year period of rainfall record (October 1948 through September 1998). A rainfall correction factor of 1.00 was applied to calibrate the rainfall data for the Seatac area rain gage to the site. The KCRTS program generates statistical reports for several hydrologic parameters including peak flow rates for estimated return periods, flow durations and flow volume. These data are useful in evaluating wetland hydrology. Wetland Hydrology Management Guidelines (King County DDES, January 1, 2012) were used in assessing effects of the proposed Allura at Tiffany Park development on the wetlands’ hydrology. The basic analysis procedure outlined in Appendix A of the Wetland Hydrology Management Guidelines was used in assessing the wetlands’ hydrology. In particular, wetland inflow durations were assessed for both existing and proposed developed conditions for both Wetland A and Wetlands B/C. Flow durations were calculated and compared for the four seasons of the year including spring, summer, fall and winter. For purposes of this study, spring is defined as extending from February 1 through May 31, summer extends from June 1 through August 31, fall extends from September 1 through November 30, and winter extends from December 1 through January 31. A 25 percent flow duration margin, bracketing the predicted predeveloped durations, was plotted on each of the flow duration charts to help assess the relative magnitude of duration comparisons. The following hydrologic parameters were also calculated and compared for existing and proposed developed basin conditions:  Peak wetland inflow rates for selected return periods. Mr. Barry Talkington Page 3 October 27, 2016  Runoff flow volumes to the wetlands. Runoff volumes calculated by KCRTS include both surface runoff and interflow (shallow groundwater). Under forested conditions, interflow is typically the dominant component. Simulation Results Under existing basin conditions, a total area of 1.99 acres was measured to drain to Wetland A and 10.35acres to Wetlands B/C (Figure 2, Table A.1). Under proposed developed conditions, 0.74 acre was measured to drain to Wetland A and 5.40 acres to Wetlands B/C (Figure 3, Table A.2). The average annual rainfall for the 50-year period of simulation record was 37.6 inches with a minimum amount of 23.8 inches in 1952 and a maximum amount of 54.6 inches in 1950 (Figure 4). A listing for the KCRTS time series generation of contributing areas is provided in Attachment B.1. Hydrologic effects of the proposed development on wetland hydrology, in terms of peak wetland inflow rates, average annual inflow volumes and wetland flow durations are described below. Measures to Supplement Wetland Hydrology The hydrology of the wetlands will be sustained by direct rainfall, runoff from the wetland buffers and discharge from selected roofs that would be collected and dispersed in the forested buffer of the wetlands. The roof area that would be directed to each wetland was determined using the hydrology model for each wetland complex, and by trial and error, attempting to maintain a reasonable balance among seasonal flow durations, peak inflow rates and annual inflow volumes. For Wetland A, a total roof area of 0.28 acre was found to be an appropriate area and would be dispersed to the wetland buffer. For Wetlands B/C, a total roof area of 0.52 acre would be dispersed to the wetland buffer. Potential overflow from Wetlands B/C would be collected at the downstream edge of the wetland complex and conveyed to the proposed stormwater vault. The upstream tributary area to Wetlands B/C includes runoff from 3.64 acres of offsite area and also runoff from onsite Wetland D. The flow contributions from these upstream tributary areas will be maintained under developed conditions. Runoff from Wetland D would be collected in a pipe and conveyed to the south and dispersed at the edge of Wetland C’s buffer. Wetland Inflow Rates Predicted peak inflow rates to the wetlands under proposed developed conditions reasonably match those for existing basin conditions (Figures 5 and 6). For Wetlands B/C, predicted developed inflow rates to the wetlands for storms larger than a 2-year event are less than those for existing conditions. For both Wetland A and Wetlands B/C, dispersion of flows to the buffer would further attenuate the rates. Mr. Barry Talkington Page 4 October 27, 2016 Wetland Inflow Volumes The average annual runoff volume to Wetland A was predicted to be 1.21 acre-feet under existing basin conditions versus 1.00 acre-feet under proposed basin conditions (Attachment B.3). The average annual runoff to Wetlands B/C was predicted to be 9.69 acre-feet under existing basin conditions versus 7.98 acre-feet under proposed basin conditions. In each case, a 17 percent decrease in runoff to the wetlands was predicted. While adding more roof drainage to the wetlands would increase the runoff volume, this additional flow would cause other hydrology inputs such as flow durations and peak inflow rates to further deviate from existing conditions. Wetland Flow Durations Due to its small basin area, the flow durations for Wetland A were more difficult to match to existing conditions than they were for Wetlands B/C. Flow durations for the wetter fall and winter months for proposed developed conditions were generally within a 25 percent margin of durations for existing conditions for Wetland A (Figures 9 and 10). The flow durations for the spring months for Wetland A were close to the lower 25 percent margin for existing conditions for Wetland A (Figure 7). Summer flow durations for Wetland A were predicted to be notably higher than those for existing basin conditions (Figure 8). The low volume of runoff that would occur over this typically dry period, however, would not result in adverse impacts to the wetland complex. In my opinion, providing an excess of runoff to the wetland during the dry summer months is preferred compared to reducing the wetland’s hydrology during these months. For Wetlands B/C, flow durations for the proposed developed conditions are close to those for existing basin conditions for spring, fall and winter months (Figures 11, 13 and 14). Summer flow durations for Wetlands B/C were predicted to be slightly higher than those for existing basin conditions (Figure 12). Key Results Based on the foregoing analysis, I believe that the proposed drainage plan will reasonably maintain the hydrology of Wetland A and Wetlands B/C. Under the proposed development, a net average decrease in runoff to both wetland complexes is predicted to occur. In general, hydrologic analyses estimated that flow durations would be within 25 percent of the existing flow durations for the spring, fall and winter months. Supplementing the wetlands’ hydrology with roof drainage, dispersed to the wetland buffers, will be an important component of the drainage plan for Wetland A and Wetlands B/C. In addition, maintaining flow contributions from offsite tributary areas for Wetlands B/C, will be important in maintaining the hydrology of these wetlands. Mr. Barry Talkington Page 5 October 27, 2016 Sincerely, Edward J. McCarthy, Ph.D., P.E. ALLURA AT TIFFANY PARKALLURA AT TIFFANY PARKFORFigure 2. Existing Basins. ALLURA AT TIFFANY PARK ALLURA AT TIFFANY PARKFORFigure 3. Developed Basins. Mr. Barry Talkington Page 9 October 27, 2016 Figure 4. Annual rainfall amounts used in hydrologic model for wetland basin. Based on Seatac precipitation gage with 1-hour time increments. 14.432.454.640.323.849.441.246.636.934.642.646.539.342.535.838.741.333.838.235.650.133.737.443.248.435.037.944.526.732.834.032.335.635.439.340.937.025.138.429.933.034.744.835.432.828.034.842.649.240.40 10 20 30 40 50 60 Rainfall Amount (IN)Calendar Year Mr. Barry Talkington Page 10 October 27, 2016 Figure 5. Wetland A peak inflow rates. 0.05 0.10 0.15 0.20 0.25 1 10 100Peak Inflow Rate (CFS)Return Period (Years) Predeveloped Developed Mr. Barry Talkington Page 11 October 27, 2016 Figure 6. Wetlands B/C peak inflow rates. 0.10 0.30 0.50 0.70 0.90 1.10 1.30 1.50 1 10 100Peak Inflow Rate (CFS)Return Period (Years) Predeveloped Developed Mr. Barry Talkington Page 12 October 27, 2016 Figure 7. Wetland A flow durations for spring months – February 1 through May 31. 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2 1.00E-05 1.00E-04 1.00E-03 1.00E-02 1.00E-01 1.00E+00Flow Rate (CFS)Probability of Exceedence Predeveloped Developed 25% Margin Low 25% Margin High Mr. Barry Talkington Page 13 October 27, 2016 Figure 8. Wetland A flow durations for summer months – June 1 through August 31. 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2 1.00E-05 1.00E-04 1.00E-03 1.00E-02 1.00E-01 1.00E+00Flow Rate (CFS)Probability of Exceedence Predeveloped Developed 25% Margin Low 25% Margin High Mr. Barry Talkington Page 14 October 27, 2016 Figure 9. Wetland A flow durations for fall months – September 1 through November 30. 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2 1.00E-05 1.00E-04 1.00E-03 1.00E-02 1.00E-01 1.00E+00Flow Rate (CFS)Probability of Exceedence Forested Developed 25% Margin Low 25% Margin High Mr. Barry Talkington Page 15 October 27, 2016 Figure 10. Wetland A flow durations for winter months – December 1 through January 31. 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2 1.00E-05 1.00E-04 1.00E-03 1.00E-02 1.00E-01 1.00E+00Flow Rate (CFS)Probability of Exceedence Predeveloped Developed 25% Margin Low 25% Margin High Mr. Barry Talkington Page 16 October 27, 2016 Figure 11. Wetlands B/C flow durations for spring months – February 1 through May 31. 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 1.00E-05 1.00E-04 1.00E-03 1.00E-02 1.00E-01 1.00E+00Flow Rate (CFS)Probability of Exceedence Predeveloped Developed 25% Margin Low 25% Margin High Mr. Barry Talkington Page 17 October 27, 2016 Figure 12. Wetlands B/C flow durations for summer months – June 1 through August 31. 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.00E-05 1.00E-04 1.00E-03 1.00E-02 1.00E-01 1.00E+00Flow Rate (CFS)Probability of Exceedence Predeveloped Developed 25% Margin Low 25% Margin High Mr. Barry Talkington Page 18 October 27, 2016 Figure 13. Wetlands B/C flow durations for fall months – September 1 through November 30. 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 1.00E-05 1.00E-04 1.00E-03 1.00E-02 1.00E-01 1.00E+00Flow Rate (CFS)Probability of Exceedence Predeveloped Developed 25% Margin Low 25% Margin High Mr. Barry Talkington Page 19 October 27, 2016 Figure 14. Wetlands B/C flow durations for winter months – December 1 through January 31. 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 1.00E-05 1.00E-04 1.00E-03 1.00E-02 1.00E-01 1.00E+00Flow Rate (CFS)Probability of Exceedence Predeveloped Developed 25% Margin Low 25% Margin High References Barghausen Consulting Engineers, November 15, 2016. Allura at Tiffany Park – Proposed Drainage and Site Plan. Kent, Wash. Barghausen Consulting Engineers, February 24, 2014. Preliminary Technical Information Report - Reserve at Tiffany Park. Kent, Wash. King County DDES, January 1, 2012. Critical Areas Mitigation Guidelines. Appendix A – Wetland Hydrology Management Guidelines. Renton, Wash. King County Department of Natural Resources, 2009. King County Surface Water Design Manual. Seattle. King County Department of Natural Resources, January 1999. King County Runoff Time Series (KCRTS) – Hydrologic Simulation Model for Implementing the Runoff- Files Methodology – Computer Software Reference Manual. Seattle. Schulz, Gary, June 3, 2014. Wetland Determination- Reserve at Tiffany Park – Preliminary Plat – City of Renton, Washington. Seattle. U.S. Department of Agriculture, Soil Conservation Service, 1973. Soil Survey of King County Area, Washington. Seattle. Attachment A. Wetland Basin Areas Table A.1. Wetland A Basin Areas under Existing and Developed Conditions Existing Conditions Basin Forest Pasture Landscape Impervious Total (AC) (AC) (AC) (AC) (AC) Onsite 1.89 0.10 - - 1.99 Total 1.89 0.10 - - 1.99 Developed Conditions Basin Forest Pasture Landscape Impervious Total (AC) (AC) (AC) (AC) (AC) Onsite 0.46 - - 0.28 0.74 Total 0.46 - - 0.28 0.74 Table A.2. Wetlands B/C Basin Areas under Existing and Developed Conditions Existing Conditions Basin Forest Pasture Landscape Impervious Total (AC) (AC) (AC) (AC) (AC) Onsite 6.42 - - - 6.42 Offsite - 1.51 1.37 1.05 3.93 Total 6.42 1.51 1.37 1.05 10.35 Developed Conditions Basin Forest Pasture Landscape Impervious Total (AC) (AC) (AC) (AC) (AC) Onsite 1.24 - - 0.52 1.76 Offsite - 1.22 1.37 1.05 3.64 Total 1.24 1.51 1.37 1.57 5.40 Attachment B.1. KCRTS Time Series KCRTS Command ------------- CREATE a new Time Series ------------------------ Production of Runoff Time Series Project Location : Sea-Tac Computing Series : wetapre.tsf Regional Scale Factor : 1.00 Data Type : Historic Creating Hourly Time Series File Loading Time Series File:C:\KC_SWDM\KC_DATA\STTF60H.rnf : Till Forest 1.89 acres Loading Time Series File:C:\KC_SWDM\KC_DATA\STTP60H.rnf : Till Pasture 0.10 acres -------------- Total Area : 1.99 acres Peak Discharge: 0.136 CFS at 9:00 on Jan 9 in 1990 Storing Time Series File:wetapre.tsf : Time Series Computed KCRTS Command ------------- Enter the Analysis TOOLS Module ------------------------------- Analysis Tools Command ---------------------- Compute PEAKS and Flow Frequencies ---------------------------------- Loading Stage/Discharge curve:wetapre.tsf : Flow Frequency Analysis LogPearson III Coefficients -------------------------------------------------------- Time Series File:wetapre.tsf Mean= -1.310 StdDev= 0.232 Project Location:Sea-Tac Skew= -0.142 Frequencies & Peaks saved to File:wetapre.pks : Analysis Tools Command ---------------------- Compute Flow DURATION and Exceedence ------------------------------------ Loading Time Series File:wetapre.tsf : Computing Interval Locations Computing Flow Durations Durations & Exceedence Probabilities to File:wetapre.dur : Analysis Tools Command ---------------------- RETURN to Previous Menu ----------------------- KCRTS Command ------------- CREATE a new Time Series ------------------------ Production of Runoff Time Series Project Location : Sea-Tac Computing Series : wetadev.tsf Regional Scale Factor : 1.00 Data Type : Historic Creating Hourly Time Series File Loading Time Series File:C:\KC_SWDM\KC_DATA\STTF60H.rnf : Till Forest 0.46 acres Loading Time Series File:C:\KC_SWDM\KC_DATA\STEI60H.rnf : Impervious 0.28 acres -------------- Total Area : 0.74 acres Peak Discharge: 0.142 CFS at 6:00 on Jan 9 in 1990 Storing Time Series File:wetadev.tsf : Time Series Computed KCRTS Command ------------- Enter the Analysis TOOLS Module ------------------------------- Analysis Tools Command ---------------------- Compute PEAKS and Flow Frequencies ---------------------------------- Loading Stage/Discharge curve:wetadev.tsf : Flow Frequency Analysis LogPearson III Coefficients -------------------------------------------------------- Time Series File:wetadev.tsf Mean= -1.105 StdDev= 0.105 Project Location:Sea-Tac Skew= 0.451 Frequencies & Peaks saved to File:wetadev.pks : Analysis Tools Command ---------------------- Compute Flow DURATION and Exceedence ------------------------------------ Loading Time Series File:wetadev.tsf : Computing Interval Locations Computing Flow Durations Durations & Exceedence Probabilities to File:wetadev.dur : Analysis Tools Command ---------------------- RETURN to Previous Menu ----------------------- KCRTS Command ------------- CREATE a new Time Series ------------------------ Production of Runoff Time Series Project Location : Sea-Tac Computing Series : wetbcpre.tsf Regional Scale Factor : 1.00 Data Type : Historic Creating Hourly Time Series File Loading Time Series File:C:\KC_SWDM\KC_DATA\STTF60H.rnf : Till Forest 6.42 acres Loading Time Series File:C:\KC_SWDM\KC_DATA\STTP60H.rnf : Till Pasture 1.51 acres Loading Time Series File:C:\KC_SWDM\KC_DATA\STTG60H.rnf : Till Grass 1.37 acres Loading Time Series File:C:\KC_SWDM\KC_DATA\STEI60H.rnf : Impervious 1.05 acres -------------- Total Area : 10.35 acres Peak Discharge: 1.23 CFS at 6:00 on Jan 9 in 1990 Storing Time Series File:wetbcpre.tsf : Time Series Computed KCRTS Command ------------- Enter the Analysis TOOLS Module ------------------------------- Analysis Tools Command ---------------------- Compute PEAKS and Flow Frequencies ---------------------------------- Loading Stage/Discharge curve:wetbcpre.tsf : Flow Frequency Analysis LogPearson III Coefficients -------------------------------------------------------- Time Series File:wetbcpre.tsf Mean= -0.290 StdDev= 0.165 Project Location:Sea-Tac Skew= 0.344 Frequencies & Peaks saved to File:wetbcpre.pks : Analysis Tools Command ---------------------- Compute Flow DURATION and Exceedence ------------------------------------ Loading Time Series File:wetbcpre.tsf : Computing Interval Locations Computing Flow Durations Durations & Exceedence Probabilities to File:wetbcpre.dur : Analysis Tools Command ---------------------- RETURN to Previous Menu ----------------------- KCRTS Command ------------- CREATE a new Time Series ------------------------ Production of Runoff Time Series Project Location : Sea-Tac Computing Series : wetbcdev.tsf Regional Scale Factor : 1.00 Data Type : Historic Creating Hourly Time Series File Loading Time Series File:C:\KC_SWDM\KC_DATA\STTF60H.rnf : Till Forest 1.24 acres Loading Time Series File:C:\KC_SWDM\KC_DATA\STTP60H.rnf : Till Pasture 1.51 acres Loading Time Series File:C:\KC_SWDM\KC_DATA\STTG60H.rnf : Till Grass 1.37 acres Loading Time Series File:C:\KC_SWDM\KC_DATA\STEI60H.rnf : Impervious 1.57 acres -------------- Total Area : 5.69 acres Peak Discharge: 1.13 CFS at 6:00 on Jan 9 in 1990 Storing Time Series File:wetbcdev.tsf : Time Series Computed KCRTS Command ------------- Enter the Analysis TOOLS Module ------------------------------- Analysis Tools Command ---------------------- Compute PEAKS and Flow Frequencies ---------------------------------- Loading Stage/Discharge curve:wetbcdev.tsf : Flow Frequency Analysis LogPearson III Coefficients -------------------------------------------------------- Time Series File:wetbcdev.tsf Mean= -0.259 StdDev= 0.128 Project Location:Sea-Tac Skew= 0.458 Frequencies & Peaks saved to File:wetbcdev.pks : Analysis Tools Command ---------------------- Compute Flow DURATION and Exceedence ------------------------------------ Loading Time Series File:wetbcdev.tsf : Computing Interval Locations Computing Flow Durations Durations & Exceedence Probabilities to File:wetbcdev.dur : Analysis Tools Command ---------------------- RETURN to Previous Menu ----------------------- KCRTS Command ------------- eXit KCRTS Program ------------------ Attachment B.2. KCRTS Peak Flow Rates Flow Frequency Analysis LogPearson III Coefficients Time Series File:wetapre.tsf Mean= -1.310 StdDev= 0.232 Project Location:Sea-Tac Skew= -0.142 ---Annual Peak Flow Rates--- -----Flow Frequency Analysis------- Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 0.060 17 2/16/49 22:00 0.136 1 89.50 0.989 0.119 4 3/03/50 16:00 0.127 2 32.13 0.969 0.127 2 2/09/51 18:00 0.121 3 19.58 0.949 0.040 32 1/30/52 9:00 0.119 4 14.08 0.929 0.031 42 1/18/53 19:00 0.118 5 10.99 0.909 0.045 28 1/06/54 5:00 0.098 6 9.01 0.889 0.079 10 2/07/55 21:00 0.096 7 7.64 0.869 0.068 13 12/20/55 17:00 0.086 8 6.63 0.849 0.053 21 12/09/56 15:00 0.080 9 5.86 0.829 0.056 20 1/16/58 20:00 0.079 10 5.24 0.809 0.046 24 1/24/59 2:00 0.079 11 4.75 0.789 0.086 8 11/20/59 21:00 0.070 12 4.34 0.769 0.046 22 2/24/61 15:00 0.068 13 3.99 0.749 0.028 44 1/03/62 2:00 0.066 14 3.70 0.729 0.037 36 11/25/62 14:00 0.064 15 3.44 0.709 0.046 25 1/01/64 18:00 0.061 16 3.22 0.690 0.033 39 11/30/64 12:00 0.060 17 3.03 0.670 0.035 38 1/06/66 3:00 0.059 18 2.85 0.650 0.079 11 1/19/67 14:00 0.057 19 2.70 0.630 0.046 23 2/03/68 23:00 0.056 20 2.56 0.610 0.046 26 12/03/68 17:00 0.053 21 2.44 0.590 0.039 34 1/13/70 23:00 0.046 22 2.32 0.570 0.033 40 12/06/70 8:00 0.046 23 2.22 0.550 0.096 7 2/28/72 3:00 0.046 24 2.13 0.530 0.042 30 1/13/73 5:00 0.046 25 2.04 0.510 0.045 27 1/15/74 2:00 0.046 26 1.96 0.490 0.070 12 12/26/74 23:00 0.045 27 1.89 0.470 0.043 29 12/02/75 20:00 0.045 28 1.82 0.450 0.005 50 3/24/77 19:00 0.043 29 1.75 0.430 0.037 37 12/10/77 17:00 0.042 30 1.70 0.410 0.022 46 2/12/79 8:00 0.041 31 1.64 0.390 0.059 18 12/15/79 8:00 0.040 32 1.59 0.370 0.033 41 12/26/80 4:00 0.040 33 1.54 0.350 0.064 15 10/06/81 15:00 0.039 34 1.49 0.330 0.057 19 1/05/83 8:00 0.038 35 1.45 0.310 0.038 35 1/24/84 11:00 0.037 36 1.41 0.291 0.019 48 2/11/85 6:00 0.037 37 1.37 0.271 0.098 6 1/18/86 21:00 0.035 38 1.33 0.251 0.080 9 11/24/86 4:00 0.033 39 1.30 0.231 0.031 43 1/14/88 12:00 0.033 40 1.27 0.211 0.019 47 4/05/89 16:00 0.033 41 1.24 0.191 0.136 1 1/09/90 9:00 0.031 42 1.21 0.171 0.118 5 4/05/91 2:00 0.031 43 1.18 0.151 0.040 33 1/27/92 17:00 0.028 44 1.15 0.131 0.041 31 3/22/93 23:00 0.023 45 1.12 0.111 0.012 49 3/03/94 3:00 0.022 46 1.10 0.091 0.061 16 2/19/95 20:00 0.019 47 1.08 0.071 0.121 3 2/09/96 1:00 0.019 48 1.05 0.051 0.066 14 1/02/97 9:00 0.012 49 1.03 0.031 0.023 45 1/07/98 11:00 0.005 50 1.01 0.011 Computed Peaks 0.161 100.00 0.990 Computed Peaks 0.141 50.00 0.980 Computed Peaks 0.122 25.00 0.960 Computed Peaks 0.096 10.00 0.900 Computed Peaks 0.091 8.00 0.875 Computed Peaks 0.077 5.00 0.800 Computed Peaks 0.050 2.00 0.500 Computed Peaks 0.033 1.30 0.231 Flow Frequency Analysis LogPearson III Coefficients Time Series File:wetadev.tsf Mean= -1.105 StdDev= 0.105 Project Location:Sea-Tac Skew= 0.451 ---Annual Peak Flow Rates--- -----Flow Frequency Analysis------- Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 0.084 20 2/16/49 21:00 0.142 1 89.50 0.989 0.131 3 3/03/50 16:00 0.132 2 32.13 0.969 0.088 14 2/09/51 2:00 0.131 3 19.58 0.949 0.063 43 10/15/51 13:00 0.119 4 14.08 0.929 0.061 45 3/24/53 15:00 0.108 5 10.99 0.909 0.075 27 12/19/53 19:00 0.105 6 9.01 0.889 0.079 22 2/07/55 17:00 0.103 7 7.64 0.869 0.078 23 12/20/55 17:00 0.101 8 6.63 0.849 0.090 13 12/09/56 14:00 0.098 9 5.86 0.829 0.077 26 12/25/57 16:00 0.097 10 5.24 0.809 0.060 47 11/18/58 13:00 0.094 11 4.75 0.789 0.078 24 11/20/59 5:00 0.094 12 4.34 0.769 0.068 34 2/14/61 21:00 0.090 13 3.99 0.749 0.062 44 11/22/61 2:00 0.088 14 3.70 0.729 0.067 38 12/15/62 2:00 0.088 15 3.44 0.709 0.077 25 12/31/63 23:00 0.088 16 3.22 0.690 0.067 36 12/21/64 4:00 0.087 17 3.03 0.670 0.069 31 1/05/66 16:00 0.085 18 2.85 0.650 0.094 12 11/13/66 19:00 0.085 19 2.70 0.630 0.105 6 8/24/68 16:00 0.084 20 2.56 0.610 0.065 39 12/03/68 16:00 0.083 21 2.44 0.590 0.069 32 1/13/70 22:00 0.079 22 2.32 0.570 0.065 40 12/06/70 8:00 0.078 23 2.22 0.550 0.103 7 2/27/72 7:00 0.078 24 2.13 0.530 0.064 42 1/13/73 2:00 0.077 25 2.04 0.510 0.068 33 11/28/73 9:00 0.077 26 1.96 0.490 0.097 10 12/26/74 23:00 0.075 27 1.89 0.470 0.065 41 12/02/75 20:00 0.072 28 1.82 0.450 0.071 29 8/26/77 2:00 0.071 29 1.75 0.430 0.098 9 9/17/78 2:00 0.070 30 1.70 0.410 0.088 15 9/08/79 15:00 0.069 31 1.64 0.390 0.085 19 12/14/79 21:00 0.069 32 1.59 0.370 0.085 18 11/21/80 11:00 0.068 33 1.54 0.350 0.119 4 10/06/81 15:00 0.068 34 1.49 0.330 0.087 17 10/28/82 16:00 0.068 35 1.45 0.310 0.072 28 1/03/84 1:00 0.067 36 1.41 0.291 0.060 46 6/06/85 22:00 0.067 37 1.37 0.271 0.094 11 1/18/86 16:00 0.067 38 1.33 0.251 0.108 5 10/26/86 0:00 0.065 39 1.30 0.231 0.052 49 11/11/87 0:00 0.065 40 1.27 0.211 0.067 37 8/21/89 17:00 0.065 41 1.24 0.191 0.142 1 1/09/90 6:00 0.064 42 1.21 0.171 0.132 2 11/24/90 8:00 0.063 43 1.18 0.151 0.070 30 1/27/92 15:00 0.062 44 1.15 0.131 0.047 50 11/01/92 16:00 0.061 45 1.12 0.111 0.053 48 11/30/93 22:00 0.060 46 1.10 0.091 0.068 35 11/30/94 4:00 0.060 47 1.08 0.071 0.101 8 2/08/96 10:00 0.053 48 1.05 0.051 0.088 16 1/02/97 6:00 0.052 49 1.03 0.031 0.083 21 10/04/97 15:00 0.047 50 1.01 0.011 Computed Peaks 0.149 100.00 0.990 Computed Peaks 0.136 50.00 0.980 Computed Peaks 0.124 25.00 0.960 Computed Peaks 0.108 10.00 0.900 Computed Peaks 0.105 8.00 0.875 Computed Peaks 0.095 5.00 0.800 Computed Peaks 0.077 2.00 0.500 Computed Peaks 0.065 1.30 0.231 Flow Frequency Analysis LogPearson III Coefficients Time Series File:wetbcpre.tsf Mean= -0.290 StdDev= 0.165 Project Location:Sea-Tac Skew= 0.344 ---Annual Peak Flow Rates--- -----Flow Frequency Analysis------- Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 0.600 17 2/16/49 21:00 1.23 1 89.50 0.989 1.20 2 3/03/50 16:00 1.20 2 32.13 0.969 0.808 7 2/09/51 15:00 1.08 3 19.58 0.949 0.426 38 1/30/52 8:00 0.920 4 14.08 0.929 0.354 43 3/24/53 15:00 0.896 5 10.99 0.909 0.488 21 12/19/53 19:00 0.849 6 9.01 0.889 0.619 16 2/07/55 17:00 0.808 7 7.64 0.869 0.628 15 12/20/55 17:00 0.796 8 6.63 0.849 0.641 14 12/09/56 14:00 0.757 9 5.86 0.829 0.466 27 1/16/58 16:00 0.706 10 5.24 0.809 0.379 41 1/23/59 23:00 0.703 11 4.75 0.789 0.678 12 11/20/59 21:00 0.678 12 4.34 0.769 0.449 35 2/14/61 21:00 0.666 13 3.99 0.749 0.314 46 11/22/61 2:00 0.641 14 3.70 0.729 0.455 31 12/15/62 2:00 0.628 15 3.44 0.709 0.495 20 12/31/63 23:00 0.619 16 3.22 0.690 0.395 40 12/21/64 4:00 0.600 17 3.03 0.670 0.453 32 1/05/66 16:00 0.575 18 2.85 0.650 0.703 11 1/19/67 14:00 0.524 19 2.70 0.630 0.524 19 8/24/68 16:00 0.495 20 2.56 0.610 0.453 33 12/03/68 16:00 0.488 21 2.44 0.590 0.460 29 1/13/70 23:00 0.482 22 2.32 0.570 0.449 36 12/06/70 8:00 0.475 23 2.22 0.550 0.849 6 2/27/72 7:00 0.474 24 2.13 0.530 0.411 39 1/13/73 2:00 0.471 25 2.04 0.510 0.442 37 11/28/73 9:00 0.471 26 1.96 0.490 0.757 9 12/26/74 23:00 0.466 27 1.89 0.470 0.462 28 12/02/75 20:00 0.462 28 1.82 0.450 0.312 47 8/26/77 2:00 0.460 29 1.75 0.430 0.475 23 9/22/78 19:00 0.458 30 1.70 0.410 0.356 42 9/08/79 15:00 0.455 31 1.64 0.390 0.575 18 12/14/79 21:00 0.453 32 1.59 0.370 0.474 24 11/21/80 11:00 0.453 33 1.54 0.350 0.896 5 10/06/81 15:00 0.453 34 1.49 0.330 0.482 22 1/05/83 8:00 0.449 35 1.45 0.310 0.471 25 1/03/84 1:00 0.449 36 1.41 0.291 0.279 48 6/06/85 22:00 0.442 37 1.37 0.271 0.796 8 1/18/86 16:00 0.426 38 1.33 0.251 0.706 10 11/24/86 3:00 0.411 39 1.30 0.231 0.324 45 1/14/88 12:00 0.395 40 1.27 0.211 0.259 49 11/05/88 14:00 0.379 41 1.24 0.191 1.23 1 1/09/90 6:00 0.356 42 1.21 0.171 1.08 3 11/24/90 8:00 0.354 43 1.18 0.151 0.453 34 1/27/92 17:00 0.342 44 1.15 0.131 0.342 44 3/22/93 22:00 0.324 45 1.12 0.111 0.227 50 11/30/93 22:00 0.314 46 1.10 0.091 0.458 30 2/19/95 17:00 0.312 47 1.08 0.071 0.920 4 2/08/96 10:00 0.279 48 1.05 0.051 0.666 13 1/02/97 6:00 0.259 49 1.03 0.031 0.471 26 10/04/97 15:00 0.227 50 1.01 0.011 Computed Peaks 1.37 100.00 0.990 Computed Peaks 1.20 50.00 0.980 Computed Peaks 1.04 25.00 0.960 Computed Peaks 0.845 10.00 0.900 Computed Peaks 0.806 8.00 0.875 Computed Peaks 0.701 5.00 0.800 Computed Peaks 0.502 2.00 0.500 Computed Peaks 0.382 1.30 0.231 Flow Frequency Analysis LogPearson III Coefficients Time Series File:wetbcdev.tsf Mean= -0.259 StdDev= 0.128 Project Location:Sea-Tac Skew= 0.458 ---Annual Peak Flow Rates--- -----Flow Frequency Analysis------- Flow Rate Rank Time of Peak - - Peaks - - Rank Return Prob (CFS) (CFS) Period 0.591 19 2/16/49 21:00 1.13 1 89.50 0.989 1.09 2 3/03/50 16:00 1.09 2 32.13 0.969 0.656 13 2/09/51 2:00 1.02 3 19.58 0.949 0.427 43 1/30/52 8:00 0.940 4 14.08 0.929 0.413 44 3/24/53 15:00 0.793 5 10.99 0.909 0.529 26 12/19/53 19:00 0.770 6 9.01 0.889 0.566 22 2/07/55 17:00 0.732 7 7.64 0.869 0.571 21 12/20/55 17:00 0.718 8 6.63 0.849 0.659 12 12/09/56 14:00 0.701 9 5.86 0.829 0.539 24 12/25/57 16:00 0.695 10 5.24 0.809 0.406 45 11/18/58 13:00 0.688 11 4.75 0.789 0.560 23 11/20/59 5:00 0.659 12 4.34 0.769 0.476 34 2/14/61 21:00 0.656 13 3.99 0.749 0.429 41 11/22/61 2:00 0.644 14 3.70 0.729 0.483 32 12/15/62 2:00 0.640 15 3.44 0.709 0.529 25 12/31/63 23:00 0.630 16 3.22 0.690 0.457 37 12/21/64 4:00 0.623 17 3.03 0.670 0.482 33 1/05/66 16:00 0.621 18 2.85 0.650 0.695 10 11/13/66 19:00 0.591 19 2.70 0.630 0.718 8 8/24/68 16:00 0.580 20 2.56 0.610 0.453 39 12/03/68 16:00 0.571 21 2.44 0.590 0.485 31 1/13/70 22:00 0.566 22 2.32 0.570 0.476 35 12/06/70 8:00 0.560 23 2.22 0.550 0.793 5 2/27/72 7:00 0.539 24 2.13 0.530 0.428 42 1/13/73 2:00 0.529 25 2.04 0.510 0.507 29 11/28/73 9:00 0.529 26 1.96 0.490 0.732 7 12/26/74 23:00 0.518 27 1.89 0.470 0.457 38 12/02/75 20:00 0.512 28 1.82 0.450 0.443 40 8/26/77 2:00 0.507 29 1.75 0.430 0.640 15 9/22/78 19:00 0.492 30 1.70 0.410 0.518 27 9/08/79 15:00 0.485 31 1.64 0.390 0.630 16 12/14/79 21:00 0.483 32 1.59 0.370 0.621 18 11/21/80 11:00 0.482 33 1.54 0.350 0.940 4 10/06/81 15:00 0.476 34 1.49 0.330 0.580 20 10/28/82 16:00 0.476 35 1.45 0.310 0.512 28 1/03/84 1:00 0.463 36 1.41 0.291 0.388 46 6/06/85 22:00 0.457 37 1.37 0.271 0.701 9 1/18/86 16:00 0.457 38 1.33 0.251 0.688 11 10/26/86 0:00 0.453 39 1.30 0.231 0.321 49 1/14/88 12:00 0.443 40 1.27 0.211 0.376 47 8/21/89 17:00 0.429 41 1.24 0.191 1.13 1 1/09/90 6:00 0.428 42 1.21 0.171 1.02 3 11/24/90 8:00 0.427 43 1.18 0.151 0.492 30 1/27/92 15:00 0.413 44 1.15 0.131 0.310 50 3/22/93 22:00 0.406 45 1.12 0.111 0.325 48 11/30/93 22:00 0.388 46 1.10 0.091 0.463 36 11/30/94 4:00 0.376 47 1.08 0.071 0.770 6 2/08/96 10:00 0.325 48 1.05 0.051 0.644 14 1/02/97 6:00 0.321 49 1.03 0.031 0.623 17 10/04/97 15:00 0.310 50 1.01 0.011 Computed Peaks 1.20 100.00 0.990 Computed Peaks 1.08 50.00 0.980 Computed Peaks 0.960 25.00 0.960 Computed Peaks 0.811 10.00 0.900 Computed Peaks 0.781 8.00 0.875 Computed Peaks 0.698 5.00 0.800 Computed Peaks 0.538 2.00 0.500 Computed Peaks 0.438 1.30 0.231 Attachment B.3. KCRTS Runoff Volumes KCRTS Command ------------- Enter the Analysis TOOLS Module ------------------------------- Analysis Tools Command ---------------------- Compute VOLUME Discharge ------------------------ Loading Time Series File:wetapre.tsf : Discharge Volume ---------------- Discharge Volume from Time Series wetapre.tsf between 10/01/48 00:00 and 09/30/98 23:59 2643779. Cu-Ft or 60.693 Ac-Ft in 18250.0 days Discharge Volume File:volwetafpre.prn : Volume Computed Analysis Tools Command ---------------------- Compute VOLUME Discharge ------------------------ Loading Time Series File:wetadev.tsf : Discharge Volume ---------------- Discharge Volume from Time Series wetadev.tsf between 10/01/48 00:00 and 09/30/98 23:59 2185299. Cu-Ft or 50.168 Ac-Ft in 18250.0 days Discharge Volume File:volwetadev.prn : Volume Computed Analysis Tools Command ---------------------- Compute VOLUME Discharge ------------------------ Loading Time Series File:wetbcpre.tsf : Discharge Volume ---------------- Discharge Volume from Time Series wetbcpre.tsf between 10/01/48 00:00 and 09/30/98 23:59 21104772. Cu-Ft or 484.499 Ac-Ft in 18250.0 days Discharge Volume File:volwetspre.prn : Volume Computed Analysis Tools Command ---------------------- Compute VOLUME Discharge ------------------------ Loading Time Series File:wetbcdev.tsf : Discharge Volume ---------------- Discharge Volume from Time Series wetbcdev.tsf between 10/01/48 00:00 and 09/30/98 23:59 17380086. Cu-Ft or 398.992 Ac-Ft in 18250.0 days Discharge Volume File:volwetbcdev.prn : Volume Computed Analysis Tools Command ---------------------- eXit KCRTS Program ------------------ End of EXEC file..Begin Interactive Mode KCRTS Command ------------- eXit KCRTS Program ------------------ Attachment C: Photos of the Subject Wetlands ▼ Photo Number 1 ▼ Photo Number 2 Date of Photo: 10-27-16 Date of Photo: 10-27-16 Location: Wetland A Location: Wetlands B/C Description: Wetland A is a depressional forested wetland with a Category 2 rating. Description: Wetlands B and C are depressional forested wetland. Attachment C: Photos of the Subject Wetlands ▼ Photo Number 3 ▼ Photo Number 4 Date of Photo: 10-27-16 Date of Photo: 10-27-16 Location: Wetlands B/C Location: Wetlands B/C Description: Wetland C has a Category 2 rating. Wetland B has a Category 3 rating. Description: Seasonal ponding of water is evidenced by the water mark of the tree in the background. Revised Tree Protection Plan - Reserve at Tiffany Park prepared by Washington Forestry Consultants dated October 4, 2016 6.3 FORESTRY AND VEGETATION MANAGEMENT SPECIALISTS WFCI 3601943-1 723 FAX 3601943-4 1 28 1919 Yelm Hwy SE, Suite C Olympia, WA 98501 URBANIRURAL FORESTRY TREE APPRAISAL HAZARD TREE ANALYSIS RIGHT-OF-WAYS VEGETATION MANAGEMENT ENVIRONMENTAL STUDIES CONTRACT FORESTERS Member of International Society of Arboriculture and Society of American Foresters - Revised Tree Protection Plan- RESERVE AT TIFFANY PARK SE 18th Street and 124th Pl. SE Renton, WA Prepared for: Barbara Yarington, Henley USA Prepared by: Washington Forestry Consultants, Inc. Original Report Date: October 23, 2014 Revised Report Date: October 4, 2016 Introduction The project proponent is planning to construct a new 96 lot subdivision on 21.66 acres at SE 18th Street in Renton, WA. The proponent has retained WFCI to: • Evaluate and inventory all trees on the site pursuant to the requirements of the City of Renton Tree Protection Ordinance. • Make recommendations for retention of significant trees, along with required protection and cultural measures. Observations Methodology WFCI has evaluated trees 6 inches diameter at breast height (DBH) and larger in the proposed project area, and assessed their potential to be incorporated into the new project. The tree evaluation phase used methodology developed by Nelda Matheny and Dr. James Clark in their 1998 publication Trees and Development: A Technical Guide to Preservation of Trees During Land Development. Site Description The site was previously logged many years ago and was not replanted. The trees on the site are all naturally regenerated. Five small wetlands are located on the site. There are no structures located on the site. There are many trails throughout the site. The Reserve at Tiffany Park – Revised Tree Protection Plan 10/04/16 Washington Forestry Consultants, Inc Page 2 Forest Inventory by Forest Cover Type There are two forest cover types for the purpose of description. Both types are natural stands. These stands were inventoried using variable area plots installed on a systematic grid across the site. This sample of the tree population will predict the total population of trees with a 95% level of confidence. The trees within the proposed tree tracts were 100% inventoried and evaluated. The location of the types is illustrated on the aerial photo in Attachment #1. Type I. -- Type I is the largest type of the site. The trees in this type are native species. The species found in this type include bigleaf maple (Acer macrophyllum), western hemlock (Tsuga heterophylla), western red cedar (Thuja plicata) and Douglas-fir (Pseudotsuga menziesii). There are a small number of other species intermixed. A total of 847 trees are projected to exist in the type, ranging in diameter from 6 to 36 inches DBH. Six hundred and thirty-two (632) of the trees were classified as sound, healthy, long-term trees in the dominant and co-dominant crown class. The other 215 trees are not long-term trees due to structural defects or poor health (dead, diseased, or hazardous). Table 1. Summary of Trees in Type I. Species DBH Range (in.) Trees/acre Total # of Trees # of Trees in Poor Health* # of Healthy Trees Species Composition of Stand Bigleaf Maple 6-36 48.7 715 174 541 84% Douglas-fir 17 1.6 21 0 21 3% Western Red Cedar 14 2.3 34 0 34 4% Western Hemlock 14-15 5.2 77 41 36 9% Sum 6-36 57.8 847 215 632 100% *Dead, diseased, or hazardous. The Reserve at Tiffany Park – Revised Tree Protection Plan 10/04/16 Washington Forestry Consultants, Inc Page 3 Type II. -- This is a conifer dominated type on the site. A total of 458 trees ranging in diameter from 6 to 26 inches at DBH are projected to be in the type. The tree species found in this type include bigleaf maple, Douglas-fir, western hemlock and western red cedar. There are a small number of other species intermixed. Three hundred and thirteen (313) trees were classified as sound, healthy, long-term trees in the dominant and co- dominant crown class. The other 145 trees are not long-term trees due to poor health (dead, diseased, or hazardous). Table 2. Summary of Trees in Type II. Species DBH Range (in.) Trees/acre Total # of Trees # of Trees in Poor Health* # of Healthy Trees Species Composition of Stand Bigleaf Maple 6-24 29.4 229 124 105 50% Douglas-fir 14-26 13.5 105 21 84 23% Western Red Cedar 18-24 2.9 23 0 23 5% Western Hemlock 10-22 12.9 101 0 101 22% Sum 6-26 58.7 458 145 313 100% *Dead, diseased, or hazardous. Summary of All Trees on the Site There are a total of 1,305 trees on the site that range from 6 to 36 inches DBH. Of these 1,305 trees, there are 360 trees that are dead, dying, or diseased, leaving 945 that are considered to be healthy trees. Bigleaf maple is the predominant tree species making up 72% of the significant trees in the forest. Table 3. Summary of all Trees on the Site. Species DBH Range (in.) Total # of Trees # of Trees in Poor Health* # of Healthy Trees Species Composition of Stand Bigleaf Maple 6-36 944 298 646 72% Douglas-fir 14-26 126 21 105 10% Western Red Cedar 18-24 57 0 57 4% Western Hemlock 10-22 178 41 137 14% Sum 6-36 1,305 360 945 100% Off-Site Impacts Tree removal on this parcel will not impact trees on any surrounding parcels. The Reserve at Tiffany Park – Revised Tree Protection Plan 10/04/16 Washington Forestry Consultants, Inc Page 4 Discussion Potential for Tree Retention The following table provides a summary of all potential tree tract areas on the site and whether the trees could be saved or removed in the project. There are 12 tracts (Tracts A, B, D, E, F, G, H, I, J, K, L, and M) that have the potential to have trees retained on them. These are illustrated on the proposed site plan in Attachment #2. A detailed summary of trees by tract, species, condition, and DBH class is provided in Table 4 below. A list of the individual trees is provided in Attachment #4. Table 4. Summary of tree inventory by Tract (see map in Attachment #2 for tract locations). Tract Description of Area # Trees- Existing* DBH Range (in) # Trees to be Removed for Health Issues* # Trees to be Removed for Grading Issues # Trees Proposed to Be Saved* A South end of Tract A 19 6-24 2 1 16 B Area surrounding Wetland A 77 6-50 2 6 69 D Area east of lots 14-32 71 6-28 10 7 54 E Between lots 32 and 33 4 6-24 1 3 0 F East of Lots 33-34 1 24 0 1 0 G Area surrounding Wetland D 4 12-28 1 0 3 H Area south of lot 39 46 6-36 1 0 45 I Area south of lots 37-38 2 15-26 0 0 2 J Area south of lot 44-45 10 7-30 0 1 9 K Area surrounding Wetlands B and C 11 8-29 0 0 11 L Area south of lot 82 17 6-36 0 1 16 M Area surrounding Wetland E 17 6-22 0 1 16 Summary 279 6-50 17 21 241 *Based on 100% field inventory in tracts on October 17 & 20, 2014 and September 28, 2016 with staked boundary lines. The inventory was done in the field and not from the surveyed map. A total of 17 trees were found in the tracts should be removed because of poor health and/or structural defects. Twenty-one trees will need to be removed because of grading (cuts or fills) for wall or street construction. The remaining 241 trees could be retained in the 12 tracts. This tree inventory was done after staking of the tree tracts. The Reserve at Tiffany Park – Revised Tree Protection Plan 10/04/16 Washington Forestry Consultants, Inc Page 5 Tree Density Calculations Title 4-4-130 of the Renton Municipal Code calls for 30% of all healthy significant trees in buildable areas to be retained on the project, or where the required number cannot be retained, replacement trees are to be planted. The following is a summary of the required and planned tree retention as based on the currently proposed plan: Total Project Area 21.66 acres Critical Areas and Buffers <1.70 acres> Rights-of-ways <4.15 acres> Buildable Area 15.81 acres Total Number of Significant Trees on Site 1,305 trees Trees Excluded from Retention Calculation: Trees that are Dead Diseased or Dangerous <360 trees> Trees in Proposed Public Streets <238 trees> Trees in Critical Areas and Buffers <72 trees> Trees on Private Easements <15 trees> Number of Healthy, Significant Trees in Buildable Area: 620 trees Required Tree Retention: 30% of healthy significant trees in buildable area: 186 trees Planned Tree Retention <241 trees> Excess of Retention over the Minimum Requirement 55 trees Required number of replacement trees: 0 trees There are 620 healthy significant trees in the buildable area of the site. At least 186 of these trees need to be retained to meet the City of Renton Code. The proposed plan retains 241 trees outside of the critical areas and buffers, an excess of 55 trees. The Reserve at Tiffany Park – Revised Tree Protection Plan 10/04/16 Washington Forestry Consultants, Inc Page 6 Recommendations Tree Protection Measures Trees to be saved must be protected during construction by a six foot high chain link fence (Attachment #8), located at the edge of the root protection zone (RPZ). The RPZ shall be the dripline of the stand of trees, or the limits of construction of the tree tract. Placards shall be placed on the fencing every 50 feet indicating the words, "NO TRESPASSING - Protected Trees". The individual tree RPZ is the dripline (6 feet minimum), unless otherwise delineated by WFCI in the field and described in the attached tree list (Attachment #4). Tree protection fences should be placed around the edge of the root protection zone (RPZ). The fence should be erected after logging but prior to the start of clearing. The fences should be maintained until the start of the landscape installation. There should be no equipment activity (including rototilling) within the root protection zone. No irrigation lines, trenches, or other utilities should be installed within the RPZ. Cuts or fills should impact no more than 20% of a tree’s root system. If topsoil is added to the root zone of a protected tree, the depth should not exceed 2 inches of a sandy loam or loamy fine sand topsoil and should not cover more than 20% of the root system. If roots are encountered outside the RPZ during construction, they should be cut cleanly with a saw and covered immediately with moist soil. Noxious vegetation within the root protection zone should be removed by hand. If a proposed save tree must be impacted by grading or fills more than allowed for by WFCI in the tree list, then the tree should be re-evaluated by WFCI to determine if the tree can be saved with mitigating measures, or if the tree should be removed. Pruning and Thinning All individual trees to be saved near or within developed areas should have their crowns raised to provide a minimum of 8 feet of ground clearance over sidewalks and landscape areas, 15 feet over parking lots or streets, and at least 10 feet of building clearance. All pruning should be done according to the ANSI A300 standards for proper pruning, and be completed by an International Society of Arboriculture Certified Arborist®, or be supervised by a Certified Arborist®. Hazard Tree Inspection WFCI should be contacted to inspect all save trees and tree tracts after initial logging to mark any additional trees for removal that are deemed to be high risk trees to targets within and outside of the save tree areas. A second inspection of the save trees should occur after the completion of grading to determine if any trees were damaged during grading activity. The Reserve at Tiffany Park – Revised Tree Protection Plan 10/04/16 Washington Forestry Consultants, Inc Page 7 Conclusions and Timeline for Activity 1. 241 trees are proposed to be retained in tree tracts within the site (outside of critical areas and their buffers). This exceeds the 186 tree minimum retention (30%) requirement by 55 trees. 2. The final, approved tree protection plan map should be included in the construction drawings for bid and construction of the project and should be labeled as such. 3. Stake and heavily flag the clearing limits. 4. Contact WFCI to attend pre-job conference and discuss tree protection issues with contractors. WFCI can verify all trees to be saved and/or removed are adequately marked for retention. 5. Complete logging. Complete necessary hazard tree removals and invasive plant removals from the tree protection areas. No equipment should enter the tree protection areas during logging. 6. Contact WFCI to inspect the tree tracts after logging, but prior to land clearing to identify any additional hazard trees that should be removed. 7. Install tree protection fences along the 'limits of construction'. The fences should be located at the limits of construction or at the dripline of the save tree or as otherwise specified by WFCI. Maintain fences throughout construction. 8. Complete clearing of the project. 9. Do not excavate stumps within 10’ of trees to be saved. These should be individually evaluated by WFCI to determine the method of removal. 10. Complete all necessary pruning on save trees or stand edges to provide at least 8’ of ground clearance near sidewalks and trails, and 15’ above all driveways or access roads. 11. Complete grading and construction of the project. 12. Contact WFCI to final inspect the tree protection areas after grading. 13. All save trees within reach of targets should be inspected annually for 2 years by a qualified professional forester retained by the homeowners association, and bi-annually thereafter. The purpose of these inspections is to identify trees that develop problems due to changing micro-site conditions and to prescribe cultural care or removal. The Reserve at Tiffany Park – Revised Tree Protection Plan 10/04/16 Washington Forestry Consultants, Inc Page 8 Summary The City of Renton Municipal Code calls for 30% of the significant trees be retained on the buildable area of the site or mitigated for. Based on the current site plan, 246 existing trees in 12 tracts will be retained. This exceeds the minimum 186 tree (30%) requirement by 55 trees. Therefore, no additional replacement trees are required. This tree protection plan coupled with 72 additional trees in the wetlands and buffers, and the healthy red alders and black cottonwoods that exist but were not counted, will help to preserve the forested character of the area. As the street trees and landscape trees fill in the buildable area over time, Tiffany Park will be a very well-treed residential community. Please give me a call if you have further questions. Respectfully submitted, Washington Forestry Consultants, Inc. Galen M. Wright, ASCA, ACF ISA Board Certified Master Arborist PN-0129 BU Certified Forester No. 44 ISA Tree Risk Assessor Qualified attachments: #1: aerial photo with forest cover types #2: site plan with tree tracts #3: private access roads on site plan #4: tree list of tree tract trees #5: individual tree rating key #6: description of tree evaluation methodology #7: glossary of terms #8: tree protection fence detail #9: assumptions and limiting conditions The Reserve at Tiffany Park – Revised Tree Protection Plan 10/04/16 Washington Forestry Consultants, Inc Page 9 Attachment #1: Aerial Photo of Reserve at Tiffany Park with Forest Cover Types (King County iMAP) Site Boundary Forest Cover Type Boundary Type I Type II NORTH No Scale Type I The Reserve at Tiffany Park – Revised Tree Protection Plan 10/04/16 Washington Forestry Consultants, Inc Page 10 Tract M Tract B Tract D Tract F Tract G Tract H Tract I Tract J Tract K Tract L Attachment #2: Reserve at Tiffany Park Proposed Tree Retention Areas and Tree Protection Fence Locations Tree Protection Fence (Typ) Tract A Tract E The Reserve at Tiffany Park – Revised Tree Protection Plan 10/04/16 Washington Forestry Consultants, Inc Page 11 Attachment #3: Reserve at Tiffany Park Private Easement Areas Private Access Easements (Typ) The Reserve at Tiffany Park – Revised Tree Protection Plan 10/04/16 Washington Forestry Consultants, Inc Page 12 Attachment #4. List of Trees in Tree Tracts. (attached) Tiffany ParkUpdated Tree Tract InventoryOctober 04, 2016Tract Tree # Species DBH (in)Crown PositionConditionRoot Protection Zone (ft)Drip Line (ft)Save or RemoveCount as Save Tree? NotesH1 Bigleaf maple 8 Suppressed Fair Protected Save YesH2 Western hemlock 9 Suppressed Fair Protected Save YesH3 Bigleaf maple 5,4 Suppressed Poor Protected Save YesH4 Bigleaf maple 7,7 Intermediate Fair Protected Save YesH5 Bigleaf maple 8 Intermediate Fair Protected Save YesH6 Douglas Fir 36,24,12 Dominant Fair Protected Save YesH7 Bigleaf maple 8 Intermediate Fair Protected Save YesH8 Bigleaf maple 6 Intermediate Fair Protected Save YesH9 Bigleaf maple 14 Codominant Good Protected Save YesH10 Bigleaf maple 10 Codominant Fair Protected Save YesH11 Douglas Fir 14 Codominant Fair Protected Save YesH12 Western redcedar 10 Suppressed Fair Protected Save YesH13 Cottonwood 30 Dominant Fair Protected Save NoH14 Bigleaf maple 5,4 Suppressed Fair Protected Save YesH15 Bigleaf maple 14 Suppressed Fair Protected Save YesH16 Bigleaf maple -6 Suppressed Fair Protected Save YesH17 Bigleaf maple 5,4 Suppressed Fair Protected Save YesH18 Bigleaf maple 9 Codominant Fair Protected Save YesH19 Bigleaf maple 7 Codominant Good Protected Save YesH20 Bigleaf maple 7 Codominant Fair Protected Save YesH21 Bigleaf maple 8 Codominant Fair Protected Save YesH22 Bigleaf maple 20,20,18 Dominant Poor Protected Save YesStem woundsH23 Western redcedar 6 Suppressed Fair Protected Save YesH24 Bigleaf maple 8 Suppressed Fair Protected Save YesH25 Cottonwood 48 Dominant Fair Protected Save NoH26 Bigleaf maple 15 Codominant Good Protected Save YesH27 Douglas Fir 16 Intermediate Fair Protected Save YesH28 Douglas Fir 14 Intermediate Fair Protected Save YesH29 Douglas Fir 27 Dominant Poor Protected Save YesH30 Bigleaf maple 19,15 Dominant Fair Protected Save YesH31 Douglas Fir 22 Codominant Fair Protected Save YesPrepared byWashington ForestryConsultants, Inc.1 Tiffany ParkUpdated Tree Tract InventoryOctober 04, 2016Tract Tree # Species DBH (in)Crown PositionConditionRoot Protection Zone (ft)Drip Line (ft)Save or RemoveCount as Save Tree? NotesH32 Cottonwood 30,14 Dominant Fair Protected Save NoH33 Cottonwood 22 Codominant Fair Protected Save NoH34 Cottonwood 8 Codominant Fair Protected Save NoH35 Cottonwood 8 Codominant Fair Protected Save NoH36 Cottonwood 7 Suppressed Fair Protected Save NoH37 Cottonwood 10 Codominant Fair Protected Save NoH38 Cottonwood 16 Dominant Fair Protected Save NoH39 Bigleaf maple 7 Intermediate Fair Protected Save YesH40 Bigleaf maple 9 Intermediate Fair Protected Save YesH41 Bigleaf maple 7 Intermediate Fair Protected Save YesH42 Cottonwood 10 Codominant Fair Protected Save NoH43 Cottonwood 11 Codominant Fair Protected Save NoH44 Cottonwood 8 Codominant Fair 6 West Save NoH45 Cottonwood 24 Dominant Fair 12 West Save NoH46 Bigleaf maple 8 Intermediate Good Protected Save YesH47 Bigleaf maple 6,5 Suppressed Good Protected Save YesH48 Douglas Fir 10 Suppressed Poor Protected Save YesH49 Bigleaf maple 28,28,8,12 Dominant Fair Protected Save YesH50 Douglas Fir 29 Dominant Good Protected Save YesH51 Douglas Fir 11 Suppressed Poor 7 SW Save YesH52 Douglas Fir 25 Dominant Fair 12 SW 16 A Save YesH53 Bigleaf maple 16 Codominant Good 12 SW 18 A Save YesH54 Bigleaf maple 9 Intermediate Fair 6 SW 12 A Save YesH55 Bigleaf maple 16,18 Dominant Poor Remove NoShallow roots, decay in stemH56 Douglas Fir 11,7 Codominant Fair 8 SW 9 A Save YesH57 Bigleaf maple 20,18,14 Dominant Fair 10 SW 16 A Save YesH58 Bigleaf maple 8 Suppressed Fair 3 SW 0 SW Save Yes1 sided crownH59 Bigleaf maple 15 Codominant Good 12 SW 12 S Save YesOn humpG60 Bigleaf maple 22 Codominant Fair 12 S 16 S & W Save YesG61 Western hemlock 22 Codominant Good 8 S & W 8 S & W Save YesG62 Bigleaf maple 12 Codominant Dead 8 W 6 W Remove No1 sided crownPrepared byWashington ForestryConsultants, Inc.2 Tiffany ParkUpdated Tree Tract InventoryOctober 04, 2016Tract Tree # Species DBH (in)Crown PositionConditionRoot Protection Zone (ft)Drip Line (ft)Save or RemoveCount as Save Tree? NotesG63 Bigleaf maple 28 Dominant Fair Protected 18 A Save YesF64 Red Alder 13 Codominant Fair Protected Save NoF65 Cottonwood 40 Dominant Very Poor Remove NoHazard tree - hollow stem and root decay.F66 Bigleaf maple 24,12 Dominant Fair 16 SW 18 A Remove NoRemove for wall;E67 Bigleaf maple 24 Codominant Good Protected Remove NoRemove for utilities;E69 Bigleaf maple 24 Codominant Good 14SW 30 A Remove NoRemove for utilities;E70 Bigleaf maple 6 Suppressed Fair 16 SW Remove NoRemove for utilities;E71 Bigleaf maple 12 Intermediate Very Poor Remove NoDecay in stem; Nearly dead;D68 Bigleaf maple 21 Codominant Good 14 SW 30 A Remove NoNext to wallD72 Douglas Fir 31 Dominant Fair Remove NoOn hump; Leans east (minimal); Will be exposed; Close to wall: Hazard TreeD73 Bigleaf maple 28 Dominant Very Poor 14 SW 0 SW Remove NoLeans East; dead stem; Kretzschmaria deusta diseaseD74 Bigleaf maple 6 Suppressed Fair 6 SW 0 SW Save YesLeans east;D75 Red Alder 17 Dominant Fair 12 SW 4 SW Save NoD76 Douglas Fir 16 Dominant Good 10 SW 8 SW Save YesD77 Western hemlock 30 Dominant Good 16 SW 18 SW Save YesD78 Bigleaf maple 22 Codominant Fair 17 W 14 W Save YesD79 Western hemlock 28 Codominant Fair Protected Save YesD80 Cottonwood 30 Dominant Fair Protected Save NoD81 Red Alder 13 Codominant Fair Protected Save NoD82 Western hemlock 12 Codominant Fair Protected Save YesD83 Red Alder 10 Codominant Dead Remove NoHazard Tree; D295 Red Alder 12 Intermediate Dead Remove NoHazard Tree; D84 Western redcedar 7 Codominant Good Protected Save YesD85 Western redcedar 7 Codominant Good Protected Save YesD86 Douglas Fir 13 Codominant Fair Protected Save YesD87 Western hemlock 14 Codominant Fair Protected Save YesD88 Bigleaf maple 19,8 Codominant Fair 16 SW 18 A Save YesPrepared byWashington ForestryConsultants, Inc.3 Tiffany ParkUpdated Tree Tract InventoryOctober 04, 2016Tract Tree # Species DBH (in)Crown PositionConditionRoot Protection Zone (ft)Drip Line (ft)Save or RemoveCount as Save Tree? NotesD89 Bigleaf maple 24 Codominant Fair 16 SW 22 A Save YesD90 Red Alder 10 Codominant Fair Protected Save NoD91 Bigleaf maple 14 Intermediate Fair Protected Save YesD92 Douglas Fir 15 Intermediate Fair Protected Save YesLeans west;D93 Douglas Fir 25 Dominant Fair Protected Save YesD94 Western hemlock 8 Suppressed Fair Protected Save YesD95 Western hemlock 23 Dominant Good Protected Save YesD96 Western redcedar 7 Suppressed Good Protected Save YesD97 Douglas Fir 25 Dominant Good Protected Save YesD98 Douglas Fir 22 Codominant Good Protected Save YesD99 Douglas Fir 26 Codominant Good Protected Save YesD100 Douglas Fir 19 Codominant Fair Protected Save YesD101 Douglas Fir 9 Intermediate Fair Protected Save YesD102 Douglas Fir 17 Codominant Fair Protected Save YesD103 Douglas Fir 14 Codominant Fair Protected Save YesD104 Western hemlock 9 Intermediate Fair Protected Save YesD105 Douglas Fir 7 Intermediate Poor Protected Save YesD106 Western hemlock 17 Codominant Fair Protected Save YesD107 Douglas Fir 28 Dominant Fair Protected Save YesD108 Western hemlock 24 Codominant Fair Protected Save YesD109 Douglas Fir 7 Intermediate Fair 4 SW 6 A Remove NoRemove for wall;D110 Douglas Fir 12 Intermediate Fair 6 SW 8 SW Save YesCrook at ~40' near topD111 Western hemlock 13 Codominant Good 12 SW 12 SW Remove NoRemove for wall;D112 Western hemlock 9 Intermediate Fair 7 SW 10 A Save YesD113 Douglas Fir 24 Dominant Good Protected Save YesD379 Douglas Fir 18 Dominant Fair Protected Save Yes D114 Douglas Fir 11 Intermediate Poor Protected Save YesD115 Douglas Fir 16 Codominant Fair Protected Save YesD116 Douglas Fir 20 Codominant Good Protected Save YesD117 Red Alder 10 Codominant Fair Protected Save NoD118 Western hemlock 18 Codominant Fair Protected Save YesPrepared byWashington ForestryConsultants, Inc.4 Tiffany ParkUpdated Tree Tract InventoryOctober 04, 2016Tract Tree # Species DBH (in)Crown PositionConditionRoot Protection Zone (ft)Drip Line (ft)Save or RemoveCount as Save Tree? NotesD119 Douglas Fir 20 Dominant Good Protected Save YesD296 Douglas Fir 6 Suppressed Poor Protected Save YesD120 Douglas Fir 24 Dominant Good Protected Save YesD121 Douglas Fir 20 Codominant Good Protected Save YesD122 Bigleaf maple 16,18 Codominant Fair Protected Save YesD123 Douglas Fir 11 Intermediate Fair Protected Save YesD124 Douglas Fir 28 Dominant Fair 12 NW 16 A Remove NoRemove for wall;D125 Douglas Fir 15 Codominant Good 12 NW 14 A Save YesLeans toward wall/ Lot 19D126 Western hemlock 13 Codominant Fair Protected Save YesD127 Douglas Fir 29 Dominant Fair Protected Save YesD128 Douglas Fir 12 Intermediate Fair Protected Save YesD129 Western redcedar 6 Suppressed Good Protected Save YesD130 Western hemlock 7 Suppressed Fair Protected Save YesD131 Douglas Fir 11 Intermediate Fair Protected Save YesD132 Douglas Fir 26 Dominant Good Protected Save YesD133 Douglas Fir 10 Suppressed Very Poor Remove NoD134 Douglas Fir 8 Dominant Poor Remove NoRemove for wall;D135 Douglas Fir 18 Codominant Good Remove NoRemove for wall;D136 Douglas Fir 10 Dominant Good 6 NW 8 A Save YesD137 Douglas Fir 7 Suppressed Poor Remove NoD138 Bigleaf maple 25 Dominant Fair Remove NoRemove for wall;D139 Bigleaf maple 30,18 Dominant Very Poor 16 W 22 A Remove NoLeans East; multiple dead stems; Kretzschmaria deusta diseaseD140 Bigleaf maple 9,11,12 Dominant Poor Remove NoD141 Red Alder 8 Codominant Fair Protected Save NoD142 Red Alder 9 Codominant Fair Protected Save NoD143 Red Alder 9 Codominant Fair Protected Save NoD144 Red Alder 12 Dominant Good 10 S Save NoLeans north;D145 Red Alder 9 Codominant Fair Protected Save NoD146 Red Alder 9 Codominant Fair Protected Save NoD147 Red Alder 10 Codominant Good Protected Save NoPrepared byWashington ForestryConsultants, Inc.5 Tiffany ParkUpdated Tree Tract InventoryOctober 04, 2016Tract Tree # Species DBH (in)Crown PositionConditionRoot Protection Zone (ft)Drip Line (ft)Save or RemoveCount as Save Tree? NotesD148 Douglas Fir 10 Codominant Dead 8 S 8 A Remove No D149 Bigleaf maple 25 Codominant Dead 12 S 15 A Remove No D150 Bigleaf maple 18 Codominant Fair 12 S 15 A Save Yes D151 Bigleaf maple 16 Codominant Fair 12 S 15 A Save Yes D152 Bigleaf maple 8 Codominant Fair 8 S 12 A Save YesB153 Bigleaf maple 18 Dominant Fair 10 S 10 A Save Yes Leans north; Topped;B154 Bigleaf maple 9 Dominant Good 4 SW 8 A Remove NoRemove for wall;B155 Bigleaf maple 20 Dominant Good 8 S 15 A Remove NoRemove for wall;B156 Bigleaf maple 22 Dominant Good 10 S 16 A Save YesB157 Bigleaf maple 22,22 Dominant Good 3 E 24 A Save YesFill; Tree O.K.;B158 Douglas Fir 19 Dominant Fair Protected Save YesB159 Bigleaf maple 20,10 Dominant Poor Protected Remove NoHollow stem;B160 American Holly 8 Codominant Poor Protected Save YesNo risk, small tree;B161 Bigleaf maple 8 Codominant Good Protected Save YesB162 Bigleaf maple 8 Codominant Good Protected Save YesB163 Bigleaf maple 9 Codominant Good Protected Save YesB164 Bigleaf maple 8 Codominant Good Protected Save YesB165 Bigleaf maple 7 Codominant Fair Protected Save YesB166 Bigleaf maple 8 Codominant Fair Protected Save YesB167 Bigleaf maple 8 Codominant Fair Protected Save YesB297 Bigleaf maple 6 Codominant Fair Protected Save YesB298 Bigleaf maple 6 Codominant Fair Protected Save YesB299 Douglas Fir 19 Codominant Fair Protected Save YesB Buffer300 Western hemlock 16 Codominant Fair Protected Save NoB301 Douglas Fir 15 Dominant Fair Protected Save YesB302 Douglas Fir 10 Codominant Dead Remove NoHazard tree; Targets lot 2 & 3;B303 Western hemlock 12 Codominant Fair Remove NoRemove due to grading - cut;B304 Douglas Fir 12 Codominant Poor Remove NoRemove due to grading - cut;B305 Bigleaf maple 8 Intermediate Fair Remove NoRemove due to grading - cut;B306 Bigleaf maple 8 Codominant Fair Remove NoRemove due to grading - cut;B361 Bigleaf maple 9 Intermediate Fair Protected Save YesPrepared byWashington ForestryConsultants, Inc.6 Tiffany ParkUpdated Tree Tract InventoryOctober 04, 2016Tract Tree # Species DBH (in)Crown PositionConditionRoot Protection Zone (ft)Drip Line (ft)Save or RemoveCount as Save Tree? NotesB362 Douglas Fir 12 Codominant Fair Protected Save YesB363 Bigleaf maple 8 Codominant Poor Protected Save YesBroken TopB364 Bigleaf maple 9 Codominant Fair Protected Save YesB168 Bigleaf maple 7 Codominant Fair Protected Save YesB169 Vine Maple 6 Suppressed Fair Protected Save YesB170 Bigleaf maple 7 Suppressed Fair Protected Save YesB171 Douglas Fir 15 Codominant Fair Protected Save YesB172 Bigleaf maple 19,7 Codominant Fair Protected Save YesB173 Bigleaf maple 11,4 Intermediate Fair Protected Save YesB174 Bigleaf maple 20,12 Dominant Fair Protected Save YesB175 Douglas Fir 7 Suppressed Fair Protected Save YesB176 Bigleaf maple 22 Codominant Fair Protected Save YesB177 Bigleaf maple 7 Suppressed Fair Protected Save YesB178 Bigleaf maple 8,8 Codominant Fair Protected Save YesB179 Bigleaf maple 7 Suppressed Poor Protected Save YesB180 Vine Maple 6 Suppressed Good Protected Save YesB181 Bigleaf maple 6 Suppressed Good Protected Save YesB182 Douglas Fir 15 Codominant Good Protected Save YesB183 Douglas Fir 15 Codominant Good Protected Save YesB184 Douglas Fir 12 Codominant Fair Protected Save YesB185 Western hemlock 14 Codominant Fair Protected Save YesB186 Western hemlock 14 Codominant Fair Protected Save YesB187 Douglas Fir 15 Codominant Fair Protected Save YesB188 Western hemlock 15 Dominant Fair Protected Save YesB189 Bigleaf maple 20 Dominant Fair Protected Save YesB190 Bigleaf maple 8 Suppressed Fair Protected Save YesB191 Douglas Fir 9 Intermediate Poor Protected Save YesB192 Douglas Fir 17 Dominant Poor Protected Save YesB193 Bigleaf maple 30 Dominant Fair Protected Save YesB194 Douglas Fir 16 Dominant Good Protected Save YesB195 Bigleaf maple 16 Dominant Good Protected Save YesPrepared byWashington ForestryConsultants, Inc.7 Tiffany ParkUpdated Tree Tract InventoryOctober 04, 2016Tract Tree # Species DBH (in)Crown PositionConditionRoot Protection Zone (ft)Drip Line (ft)Save or RemoveCount as Save Tree? NotesB196 Bigleaf maple 7 Suppressed Good Protected Save YesB197 Douglas Fir 30 Dominant Fair Protected Save Yes1 stem already cut;B198 Bigleaf maple 11,12 Codominant Poor Protected Save YesB199 Bigleaf maple 12,11 Codominant Fair Protected Save YesB200 Bigleaf maple 14 Codominant Fair Protected Save YesB201 Bigleaf maple 26 Dominant Good Protected Save YesB202 Bigleaf maple 24-22 Dominant Fair Protected Save YesB203 Bigleaf maple 12 Codominant Good Protected Save YesB204 Bigleaf maple 8 Codominant Fair Protected Save YesB205 Bigleaf maple 22 Dominant Fair Protected Save YesB206 Bigleaf maple 8 Intermediate Fair Protected Save YesB207 Bigleaf maple 10 Codominant Good Protected Save YesB208 Bigleaf maple 10 Codominant Fair Protected Save YesB209 Bigleaf maple 7 Codominant Fair Protected Save YesB210 Bigleaf maple 6 Intermediate Fair Protected Save YesB211 Western redcedar 6 Intermediate Fair Protected Save YesB212 Bigleaf maple 10 Codominant Fair Protected Save YesB213 Douglas Fir 28 Dominant Fair Protected Save YesB214 Bigleaf maple 10 Dominant fair Protected Save YesB215 Bigleaf maple 28,17 Dominant Fair Protected Save YesB216 Western hemlock 14 Dominant Very Poor Remove NoOn lot 1 - under wall;B217 Bigleaf maple 7 Codominant Good Protected Save YesM218 Bigleaf maple 8 Codominant Good Protected Save YesM219 Douglas Fir 22 Dominant Good Protected Save YesM220 Bigleaf maple 9 Codominant Good Protected Save YesM221 Bigleaf maple 7 Intermediate Fair Protected Save YesM222 Bigleaf maple 9 Intermediate Fair Protected Save YesM223 Bigleaf maple 10 Codominant Fair Protected Save YesM224 Bigleaf maple 15 Dominant Fair Protected Save YesM225 Bigleaf maple 5 Intermediate Fair Protected Save NoTree undersize - do not count;M226 Bigleaf maple 10 Codominant Fair Protected Save YesPrepared byWashington ForestryConsultants, Inc.8 Tiffany ParkUpdated Tree Tract InventoryOctober 04, 2016Tract Tree # Species DBH (in)Crown PositionConditionRoot Protection Zone (ft)Drip Line (ft)Save or RemoveCount as Save Tree? NotesM227 Bigleaf maple 12 Codominant Fair Protected Save YesM228 Bigleaf maple 15 Codominant Fair Protected Save YesM229 Bigleaf maple 6 Suppressed Fair Protected Save YesM230 Bigleaf maple 9 Codominant Fair Protected Save YesM231 Bigleaf maple 10 Codominant Fair Protected Save YesM232 Cottonwood 16 Dominant Fair Remove NoRemove due to grading - cut; M364Bigleaf maple 12 Dominant Good Protected Save YesWas #363 on survey mapM365 Douglas Fir 14 Dominant Good Protected Save YesM Buffer366 Cherry 6 Dominant Fair Protected Save NoM Buffer367 Cherry 7 Dominant Poor Protected Save NoM Buffer368 Bigleaf maple 10,8,9 Codominant Fair Protected Save NoM Buffer369 Cherry 7,5 Codominant Fair Protected Save NoM Buffer370 Bigleaf maple 8 Intermediate Fair Protected Save NoM Buffer371 Bigleaf maple 22 Dominant Poor Protected Save NoNo # on tree;M Buffer372 Bigleaf maple 13 Codominant Fair Protected Save NoNo # on tree;M Buffer373 Bigleaf maple 22 Dominant Fair Protected Save NoNo # on tree;M378 Bigleaf maple 8 Intermediate Very Poor Protected Save? YesNo # on tree; next to neighbor's yardA374 Scouler willow 10,10,10 Dominant Poor Remove NoPoor quality tree;A375 Cascara 7 Codominant Poor Protected Save YesA233 Douglas Fir 28 Dominant Good 12 E 16 A Save YesA234 Bigleaf maple 8 Codominant Fair Protected Save YesA235 Douglas Fir 20 Codominant Fair Protected Save YesA236 Douglas Fir 26 Dominant Fair Protected Save YesA237 Western redcedar 8 Intermediate Good Protected Save YesA238 Douglas Fir 24 Dominant Fair Protected Save YesA239 Bigleaf maple 6 Suppressed Fair Protected Save YesA240 Bigleaf maple 16 Dominant Good Protected Save YesA241 European White Birch 7 Dominant Fair Protected Save YesLeans over neighbors yard;A242 Western hemlock 15 Dominant Very Poor Remove NoA243 Western redcedar 8 Codominant Good Protected Save YesA244 Douglas Fir 15,9 Codominant Fair Remove NoToo close to wall;Prepared byWashington ForestryConsultants, Inc.9 Tiffany ParkUpdated Tree Tract InventoryOctober 04, 2016Tract Tree # Species DBH (in)Crown PositionConditionRoot Protection Zone (ft)Drip Line (ft)Save or RemoveCount as Save Tree? NotesA245 Bigleaf maple 19 Dominant Fair 14 E 16 A Save YesA246 Cherry 8 Dominant Fair Protected Save YesA247 Western redcedar 8 Codominant Good Protected Save YesA248 Bigleaf maple 10 Codominant Good Protected Save YesA249 Bigleaf maple 6,5 Suppressed Fair Protected Save YesA250 Cottonwood 36 Dominant Poor Remove NoHazard tree; Branches over lot lines;L251 Douglas Fir 6 Codominant Fair Protected Save YesL252 Douglas Fir 7 Codominant Fair Protected Save YesL253 Douglas Fir 6 Codominant Fair Protected Save YesL254 Douglas Fir 6 Codominant Fair Protected Save YesL255 Bigleaf maple 6 Suppressed Fair Protected Save YesL256 Red Alder 16 Codominant Poor Remove NoDying; Hazard tree;L257 Douglas Fir 26 Dominant Fair Protected Save YesL258 Douglas Fir 22 Codominant Fair Protected Save YesL259 Red Alder 12 Codominant Fair Protected Save NoL260 Cascara 6,5 Intermediate Fair Protected Save YesL261 Cascara 8 Intermediate Fair Protected Save YesL262 Bigleaf maple 30 Dominant Good Protected Save YesL263 Douglas Fir 30 Dominant Fair Protected Save YesL264 Western redcedar 6 Codominant Good Protected Save YesL265 Western redcedar 6 Codominant Good Protected Save YesL266 Western redcedar 8 Codominant Good Protected Save YesL267 Douglas Fir 25 Dominant Good Protected Save YesL268 Western redcedar 7 Suppressed Good 6 W 6 A Save YesL376 Bigleaf maple 36,13 Dominant Good Remove NoToo close to R/W edge;K269 Red Alder 10 Codominant Fair 6 W 8 A Save NoK270 Western hemlock 26 Dominant Fair Protected Save YesK271 Bigleaf maple 16 Dominant Good Protected Save YesK272 Bigleaf maple 6 Suppressed Good 4 W 6 A Save YesK273 Bigleaf maple 11 Codominant Fair Protected Save YesK274 Bigleaf maple 14 Codominant Fair Protected Save YesPrepared byWashington ForestryConsultants, Inc.10 Tiffany ParkUpdated Tree Tract InventoryOctober 04, 2016Tract Tree # Species DBH (in)Crown PositionConditionRoot Protection Zone (ft)Drip Line (ft)Save or RemoveCount as Save Tree? NotesK275 Bigleaf maple 16,10 Codominant Fair Protected Save YesK276 Bigleaf maple 29 Dominant Good Protected Save YesK277 Bigleaf maple 18 Codominant Fair Protected Save YesK278 Bigleaf maple 21 Codominant Good Protected Save YesK279 Bigleaf maple 8 Codominant Good Protected Save YesK377 Bigleaf maple 16 Dominant Good 5 E 18 A Save YesFill; Tree O.K.;J280 Vine Maple 10,6,4 Suppressed Good 6 NW 8 A Save YesFill; Tree O.K.;J281 Bigleaf maple 8 Suppressed Good Protected Save YesJ282 Bigleaf maple 9 Suppressed Good Protected Save YesJ283 Bigleaf maple 15 Codominant Good Protected Save YesJ284 Bigleaf maple 30 Dominant Good Protected Save YesJ285 Bigleaf maple 11 Codominant Good Protected Save YesJ286 Bigleaf maple 8 Suppressed Good Protected Save YesJ287 Bigleaf maple 9 Codominant Good 7 E 8 A Save YesFill; Tree O.K.;J288 Bigleaf maple 7 Codominant Good 6 E 7 A Save YesJ289 Bigleaf maple 8 Codominant Fair Remove NoUnder wall;I290 Bigleaf maple 26 Dominant Fair Protected Save YesI291 Bigleaf maple 15 Intermediate Fair Protected Save YesI292 Cottonwood 30 Dominant Fair Protected Save NoI293 Cottonwood 24 Dominant Fair Protected Save NoI294 Cottonwood 22 Dominant Fair Protected Save No1) Root protection zone = Distance to cut or fill needed to protect tree; Labeled as distance to the north (N), south (S), southwest (SW), etc.2) Dripline = Average dripline radius, or the radius to a cardinal direction when only a portion of dripline will be disturbed; 3) 'Protected' = Tree is surrounded by 'Save' trees;Prepared byWashington ForestryConsultants, Inc.11 The Reserve at Tiffany Park – Revised Tree Protection Plan 10/04/16 Washington Forestry Consultants, Inc Page 13 Attachment #5: Individual Tree Rating Key for Tree Condition RATING SYMBOL DEFINITION Very Good VG • Balanced crown that is characteristic of the species • Normal lateral and terminal branch growth rates for the species and soil type • Stem sound, normal bark vigor • No root problems • No insect or disease problems • Long-term, attractive tree Good G • Crown lacking symmetry but nearly balanced • Normal lateral and terminal branch growth rates for the species and soil type • Minor twig dieback O.K. • Stem sound, normal bark vigor • No root problems • No or minor insect or disease problems – insignificant • Long-term tree Fair F • Crown lacking symmetry due to branch loss • Slow lateral and terminal branch growth rates for the species and soil type • Minor and major twig dieback – starting to decline • Stem partly unsound, slow diameter growth and low bark vigor • Minor root problems • Minor insect or disease problems • Short-term tree 10-30 years RATING SYMBOL DEFINITION Poor P • Major branch loss – unsymmetrical crown • Greatly reduced growth • Several structurally import dead or branch scaffold branches • Stem has bark loss and significant decay with poor bark vigor • Root damage • Insect or disease problems – remedy required • Short-term tree 1-10 years Very Poor VP • Lacking adequate live crown for survival and growth • Severe decline • Minor and major twig dieback • Stem unsound, bark sloughing, previous stem or large branch failures, very poor bark vigor • Severe root problems or disease • No or minor insect or disease problems • Mortality expected within the next few years Dead DEAD • Dead The Reserve at Tiffany Park – Revised Tree Protection Plan 10/04/16 Washington Forestry Consultants, Inc Page 14 Cultural Care Needs: ABBRV. ACTIVITY DESCRIPTION CC Crown Cleaning Pruning of dead, dying, diseased, damaged, or defective branches over 1/2 inch in diameter –includes removal of dead tops CT Crown Thinning Pruning of branches described in crown cleaning, plus thinning of up to 20% of the live branches over ½ inch diameter. Branch should be 1/3 to ½ the diameter of the lateral branch. Thinning should be well distributed throughout crown of tree, and should release healthy, long-term branches. RC Crown Reduction Reduction of the crown of a tree by pruning to lateral branches. Generally used to remove declining branches or to lighten end weight on long branches. CR Crown Raising Pruning of lower branches to remove deadwood or to provide ground or building clearances. RMV Remove Remove tree due to decline or hazardous conditions that cannot be mitigated by pruning. RS Remove Sprouts Remove basal sprouts from stem of tree. Rep Replace Tree is small – is in decline or dead. Replace with suitable tree species. HT Hazard Tree Tree is hazardous and cannot be mitigated by pruning. Recommendation is to remove tree. None No Work No work necessary at this time. The Reserve at Tiffany Park – Revised Tree Protection Plan 10/04/16 Washington Forestry Consultants, Inc Page 15 Attachment #6: Description of Tree Evaluation Methodology The evaluation of the tree condition on this site included the visual assessment of: 1. Live-crown ratio, 2. Lateral and terminal branch growth rates, 3. Presence of dieback in minor and major scaffold branches and twigs, 4. Foliage color, 5. Stem soundness and other structural defects, 6. Visual root collar examination, 7. Presence of insect or disease problems. 8. Windfirmness if tree removal will expose this tree to failure. In cases where signs of internal defect or disease were suspected, a core sample was taken to look for stain, decay, and diameter growth rates. Also, root collars were exposed to look for the presence of root disease. In all cases, the overall appearance of the tree was considered relative to its ability to add value to either an individual lot or the entire subdivision. Also, the scale of the tree and its proximity to both proposed and existing houses was considered. Lastly, the potential for incorporation into the project design is evaluated, as well as potential site plan modifications that may allow otherwise removed tree(s) to be both saved and protected in the development. Trees that are preserved in a development must be carefully selected to make sure that they can survive construction impacts, adapt to a new environment, and perform well in the landscape. Healthy, vigorous trees are better able to tolerate impacts such as root injury, changes in soils moisture regimes, and soil compaction than are low vigor trees. Structural characteristics are also important in assessing suitability. Trees with significant decay and other structural defects that cannot be treated are likely to fail. Such trees should not be preserved in areas where damage to people or property could occur. Trees that have developed in a forest stand are adapted to the close, dense conditions found in such stands. When surrounding trees are removed during clearing and grading, the remaining trees are exposed to extremes in wind, temperature, solar radiation, which causes sunscald, and other influences. Young, vigorous trees with well-developed crowns are best able to adapt to these changing site conditions. The Reserve at Tiffany Park – Revised Tree Protection Plan 10/04/16 Washington Forestry Consultants, Inc Page 16 Attachment #7: Glossary of Forestry and Arboricultural Terminology DBH: Diameter at Breast Height (measured 4.5 ft. above the ground line on the high side of the tree). Caliper: In Issaquah - Caliper is referring to diameter measurement at DBH. Live Crown Ratio: Ratio of live foliage on the stem of the tree. Example: A 100’ tall tree with 40 feet of live crown would have a 40% live crown ratio. Conifers with less than 30% live crown ratio are generally not considered to be long-term trees in forestry. Crown: Portion of a trees stem covered by live foliage. Crown Position: Position of the crown with respect to other trees in the stand. Dominant Crown Position: Receives light from above and from the sides. Codominant Crown Position: Receives light from above and some from the sides. Intermediate Crown Position: Receives little light from above and none from the sides. Trees tend to be slender with poor live crown ratios. Suppressed Crown Position: Receives no light from above and none from the sides. Trees tend to be slender with poor live crown ratios. The Reserve at Tiffany Park – Revised Tree Protection Plan 10/04/16 Washington Forestry Consultants, Inc Page 17 Attachment #8: Tree Protection Fence Detail 6 ft. Temporary Chain Link Fence NO TRESPASSING - Protected Trees The Reserve at Tiffany Park – Revised Tree Protection Plan 10/04/16 Washington Forestry Consultants, Inc Page 18 Attachment #9: Assumptions and Limiting Conditions 1) Any legal description provided to the Washington Forestry Consultants, Inc. is assumed to be correct. Any titles and ownership's to any property are assumed to be good and marketable. No responsibility is assumed for matters legal in character. Any and all property is appraised or evaluated as though free and clear, under responsible ownership and competent management. 2) It is assumed that any property is not in violation of any applicable codes, ordinances, statutes, or other governmental regulations, unless otherwise stated. 3) Care has been taken to obtain all information from reliable sources. All data has been verified insofar as possible; however, Washington Forestry Consultants, Inc. can neither guarantee nor be responsible for the accuracy of information. 4) Washington Forestry Consultants, Inc. shall not be required to give testimony or to attend court by reason of this report unless subsequent contractual arrangements are made, including payment of an additional fee for such services as described in the fee schedule and contract of engagement. 5) Loss or alteration of any part of this report invalidated the entire report. 6) Possession of this report or a copy thereof does not imply right of publication or use for any purpose by any other than the person to whom it is addressed, without the prior expressed written or verbal consent of Washington Forestry Consultants, Inc. 7) Neither all or any part of the contents of this report, nor copy thereof, shall be conveyed by anyone, including the client, to the public through advertising, public relations, news, sales or other media, without the prior expressed written or verbal consent of Washington Forestry Consultants, Inc. -- particularly as to value conclusions, identity of Washington Forestry Consultants, Inc., or any reference to any professional society or to any initialed designation conferred upon Washington Forestry Consultants, Inc. as stated in its qualifications. 8) This report and any values expressed herein represent the opinion of Washington Forestry Consultants, Inc., and the fee is in no way contingent upon the reporting of a specified value, a stipulated result, the occurrence neither of a subsequent event, nor upon any finding in to reported. 9) Sketches, diagrams, graphs, and photographs in this report, being intended as visual aids, are not necessarily to scale and should not be construed as engineering or architectural reports or surveys. 10) Unless expressed otherwise: 1) information contained in this report covers only those items that were examined and reflects the condition of those items at the time of inspection; and 2) the inspection is limited to visual examination of accessible items without dissection, excavation, probing, or coring. There is no warranty or guarantee, expressed or implied, that problems or deficiencies of the tree or other plant or property in question may not arise in the future. Note: Even healthy trees can fail under normal or storm conditions. The only way to eliminate all risk is to remove all trees within reach of all targets. Annual inspections by an ISA Certified Arborist or Certified Forester will reduce the potential of tree failures. It is impossible to predict with certainty that a tree will stand or fail, or the timing of the failure. It is considered an ‘Act of God’ when a tree fails, unless it is directly felled or pushed over by man’s actions. Geotechnical Engineering Study Allura at Tiffany Park prepared by Earth Solutions NW, LLC dated November 11, 2016 6.4 EarthSolutionsNWLLC EarthSolutions NW LLC 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 ALLURA AT TIFFANY PARK SOUTHEAST 18th STREET & MONROE AVENUE SOUTHEAST RENTON,WASHINGTON ES-3633.03 Drwn. Checked Date Date Proj.No. Plate Earth Solutions NWLLC Geotechnical Engineering,Construction Monitoring EarthSolutionsNWLLC EarthSolutions NW LLC and Environmental Sciences Vicinity Map Allura at Tiffany Park Renton,Washington MRS KDH 11/11/2016 Nov.2016 3633.03 1 NORTH 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 Plate Proj.No. Date Checked By Drwn.ByEarthSolutionsNWLLCGeotechnicalEngineering,ConstructionMonitoringandEnvironmentalSciencesEarthSolutionsNWLLCEarthSolutionsNWLLCTestPitLocationPlanAlluraatTiffanyParkRenton,WashingtonMRS KDH 11/11/2016 3633.03 2NORTH080160320 Sc ale in Feet1"=160' 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. LEGEND Approximate Location of ESNW Test Pit,Proj.No. ES-3633.03,Nov.2016 Approximate Location of AESI Exploration Pit, Proj.No.KE120359A, Sept.2012 Subject Site Proposed Lot Number Wetland (Delineated by Others) MERCER ISLAND PIPELINE R/W TP-1 TP-2 TP-3 TP-4 EP-1 EP-2 EP-3 EP-4 EP-5 EP-6 EP-7 EP-8EP-9 EP-10 EP-11 TP-1 EP-12 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 414243 44 45 46 47 484950515253 545556 57 58 59 60 61 62 63 64 65 66 676869707172 73 74 75 76 7778 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 Tract A Tract B Tract C Tract D Tract E Tract F Tract H Tract I Tract J Tract K Tract L Tract M Tract G Drainage, Landscaping &Utilities EP-1 39 S.E. 158T H ST R EET 1 2 4 TH P L ACE S . E .S.E. 18 T H ST R EET S.E. 18TH STREET ROAD A Drwn. Checked Date Date Proj.No. Plate Earth Solutions NWLLC Geotechnical Engineering,Construction Monitoring and Environmental Sciences EarthSolutionsNWLLC EarthSolutions NW LLC RETAINING WALL DRAINAGE DETAIL 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-inch 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 Sheet Drain (See Note) Floor Slab (W here Applicable) Allura at Tiffany Park Renton,Washington MRS KDH 11/11/2016 Nov.2016 3633.03 3 Drwn. Checked Date Date Proj.No. Plate Earth Solutions NWLLC Geotechnical Engineering,Construction Monitoring and Environmental Sciences EarthSolutionsNWLLC EarthSolutions NW LLC 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 DRAW ING Allura at Tiffany Park Renton,Washington MRS KDH 11/11/2016 Nov.2016 3633.03 4 Tab 7.0 16055.016.doc 7.0 OTHER PERMITS 7.1 Postmaster / Mailbox Locations Approval 7.2 Roadway Easement and Agreement for 124th Pl S.E. 7.3 NPDES Permit dated March 22, 2017 Postmaster / Mailbox Locations Approval dated February 23, 2017 7.1 Roadway Easement and Agreement for 124th Place SE 7.2 NPDES Permit dated March 23, 2017 7.3 Tab 8.0 16055.016.doc 8.0 CONSTRUCTION STORMWATER POLLUTION PREVENTION PL AN (CSWPP) ANALYSIS AND DESIGN A. Erosion and Sediment Control (ESC) Plan Analysis and Design The erosion and sediment control plans were prepared in accordance with the 2009 King County Surface Water Design Manual, 2010 City of Renton Amendments to the KCSWDM, and standard industry practices throughout the construction process to limit the amount of sediment traveling into the downstream systems. The permanent drainage facility in Tract A will be constructed to provide sediment retention on site. Prior To its construction a large sediment pond may be used. Additional BMPs that are proposed include a rock construction entrance located at the roadway stub for SE 18th Street in the North West Corner of the Site, silt fence where needed, straw mulch for the areas that reach final grade in the lot areas, V-ditches with rock check dams, and hydroseeding. Clearing limits have been established as shown on the engineering plans. Sizing Calculations for the Sediment Ponds shown on the plans are included within this section of the report. B. Stormwater Pollution Prevention and Spill (SWPPS) Plan Design A SWPPS plan has been submitted as a separate document under the Early Clear and Grad permit application. A copy of the NPDES Permit has been included within section 7.3 of this report. Tab 9.0 16055.016.doc 9.0 BOND QUANTITIES, FACILITY SUMMARIES, AND DECLARATION OF COVENANT 9.1 Bond Quantities 9.2 Facility Summary Form Bond Quantities9.1 Planning Division |1055 South Grady Way – 6th Floor | Renton, WA 98057 (425) 430-7200Date Prepared: Name:PE Registration No:Firm Name:Firm Address:Phone No.Email Address:Project Name: Project Owner:CED Plan # (LUA):Phone:CED Permit # (U):Address: Site Address:Street Intersection:Addt'l Project Owner:Parcel #(s):Phone:Address: Clearing and grading greater than or equal to 5,000 board feet of timber? Yes/No:YESWater Service Provided by:If Yes, Provide Forest Practice Permit #:Sewer Service Provided by: SITE IMPROVEMENT BOND QUANTITY WORKSHEETPROJECT INFORMATIONCITY OF RENTONCITY OF RENTON1 Select the current project status/phase from the following options: For Approval - Preliminary Data Enclosed, pending approval from the City; For Construction - Estimated Data Enclosed, Plans have been approved for contruction by the City; Project Closeout - Final Costs and Quantities Enclosed for Project Close-out SubmittalN/AEngineer Stamp Required (all cost estimates must have original wet stamp and signature)Clearing and GradingUtility ProvidersProject Location and DescriptionProject Owner InformationAllura at Tiffany parkBellevue, WA 98004See BelowMainvue Wa, LLC(425) 646-402212/5/2016Prepared by:FOR APPROVALProject Phase 1btalkington@barghausen.comBarry J Talkington41423Barghausen Consulting Engineers, Inc.18215 72nd Avenue South(425) 251-6222S.E. 18th Street and 124th Place S.E.1110 112th Ave NE, Suite 202N/AN/AU16006368N/AAbbreviated Legal Description:212305-9044-02, 212-9051-02, 212605-9054-09, & 212605-9061-00N/APage 2 of 14Ref 8-H Bond Quantity WorksheetSECTION I PROJECT INFORMATIONUnit Prices Updated: 06/14/2016Version: 06/14/2016Printed 12/5/2016 CED Permit #:U16006368UnitReference #PriceUnitQuantity CostBackfill & compaction-embankmentESC-16.50$ CY Check dams, 4" minus rockESC-2SWDM 5.4.6.380.00$ Each947,520.00Catch Basin ProtectionESC-335.50$ Each8284.00Crushed surfacing 1 1/4" minusESC-4WSDOT 9-03.9(3)95.00$ CY DitchingESC-59.00$ CY Excavation-bulkESC-62.00$ CY Fence, siltESC-7SWDM 5.4.3.11.50$ LF35005,250.00Fence, Temporary (NGPE)ESC-81.50$ LF24003,600.00Geotextile FabricESC-92.50$ SY Hay Bale Silt TrapESC-100.50$ Each HydroseedingESC-11SWDM 5.4.2.40.80$ SY5760046,080.00Interceptor Swale / DikeESC-121.00$ LF Jute MeshESC-13SWDM 5.4.2.23.50$ SY Level SpreaderESC-141.75$ LF Mulch, by hand, straw, 3" deepESC-15SWDM 5.4.2.12.50$ SY Mulch, by machine, straw, 2" deepESC-16SWDM 5.4.2.12.00$ SY Piping, temporary, CPP, 6"ESC-1712.00$ LF Piping, temporary, CPP, 8"ESC-1814.00$ LF Piping, temporary, CPP, 12"ESC-1918.00$ LF116020,880.00Plastic covering, 6mm thick, sandbaggedESC-20SWDM 5.4.2.34.00$ SY Rip Rap, machine placed; slopesESC-21WSDOT 9-13.1(2)45.00$ CY Rock Construction Entrance, 50'x15'x1'ESC-22SWDM 5.4.4.11,800.00$ Each Rock Construction Entrance, 100'x15'x1'ESC-23SWDM 5.4.4.13,200.00$ Each13,200.00Sediment pond riser assemblyESC-24SWDM 5.4.5.22,200.00$ Each24,400.00Sediment trap, 5' high berm ESC-25SWDM 5.4.5.119.00$ LF70013,300.00Sed. trap, 5' high, riprapped spillway berm section ESC-26SWDM 5.4.5.170.00$ LF604,200.00Seeding, by handESC-27SWDM 5.4.2.41.00$ SY Sodding, 1" deep, level groundESC-28SWDM 5.4.2.58.00$ SY Sodding, 1" deep, sloped groundESC-29SWDM 5.4.2.510.00$ SY TESC SupervisorESC-30110.00$ HR Water truck, dust controlESC-31SWDM 5.4.7140.00$ HR UnitReference #PriceUnitQuantity Cost EROSION/SEDIMENT SUBTOTAL:108,714.00SALES TAX @ 9.5%10,327.83EROSION/SEDIMENT TOTAL:119,041.83(A)SITE IMPROVEMENT BOND QUANTITY WORKSHEETFOR EROSION & SEDIMENT CONTROLDescription No.(A)WRITE-IN-ITEMS Page 3 of 14Ref 8-H Bond Quantity WorksheetSECTION II.a EROSION_CONTROLUnit Prices Updated: 06/14/2016Version: 06/14/2016Printed 12/5/2016 CED Permit #:U16006368ExistingFuture PublicPrivateRight-of-WayImprovementsImprovements(D) (E)DescriptionNo. Unit PriceUnitQuant.CostQuant.CostQuant.CostQuant.CostGENERAL ITEMS Backfill & Compaction- embankmentGI-16.00$ CY1440086,400.0057600345,600.00Backfill & Compaction- trenchGI-29.00$ CYClear/Remove Brush, by hand (SY)GI-31.00$ SYBollards - fixedGI-4240.74$ EachBollards - removableGI-5452.34$ Each114,975.74Clearing/Grubbing/Tree RemovalGI-610,000.00$ Acre4.4644,600.0013.86138,600.00Excavation - bulkGI-72.00$ CY1440028,800.0057600115,200.00Excavation - TrenchGI-85.00$ CYFencing, cedar, 6' highGI-920.00$ LFFencing, chain link, 4'GI-1038.31$ LFFencing, chain link, vinyl coated, 6' highGI-1120.00$ LF1603,200.00Fencing, chain link, gate, vinyl coated, 20' GI-121,400.00$ EachFill & compact - common barrowGI-1325.00$ CYFill & compact - gravel baseGI-1427.00$ CYFill & compact - screened topsoilGI-1539.00$ CYGabion, 12" deep, stone filled mesh GI-1665.00$ SYGabion, 18" deep, stone filled mesh GI-1790.00$ SYGabion, 36" deep, stone filled meshGI-18150.00$ SYGrading, fine, by handGI-192.50$ SYGrading, fine, with graderGI-202.00$ SYMonuments, 3' LongGI-21250.00$ Each164,000.00Sensitive Areas SignGI-227.00$ EachSodding, 1" deep, sloped groundGI-238.00$ SYSurveying, line & gradeGI-24850.00$ DaySurveying, lot location/linesGI-251,800.00$ AcreTopsoil Type A (imported)GI-2628.50$ CYTraffic control crew ( 2 flaggers )GI-27120.00$ HRTrail, 4" chipped woodGI-288.00$ SYTrail, 4" crushed cinderGI-299.00$ SYTrail, 4" top courseGI-3012.00$ SYConduit, 2"GI-315.00$ LFWall, retaining, concreteGI-3255.00$ SF2660146,300.00295001,622,500.00Wall, rockeryGI-3315.00$ SF6900103,500.00SUBTOTAL THIS PAGE:313,300.002,330,375.74(B)(C)(D)(E)SITE IMPROVEMENT BOND QUANTITY WORKSHEETFOR STREET AND SITE IMPROVEMENTSQuantity Remaining (Bond Reduction) (B)(C)Page 4 of 14Ref 8-H Bond Quantity WorksheetSECTION II.b TRANSPORTATIONUnit Prices Updated: 06/14/2016Version: 06/14/2016Printed 12/5/2016 CED Permit #:U16006368ExistingFuture PublicPrivateRight-of-WayImprovementsImprovements(D) (E)DescriptionNo. Unit PriceUnitQuant.CostQuant.CostQuant.CostQuant.CostSITE IMPROVEMENT BOND QUANTITY WORKSHEETFOR STREET AND SITE IMPROVEMENTSQuantity Remaining (Bond Reduction) (B)(C)ROAD IMPROVEMENT/PAVEMENT/SURFACINGAC Grinding, 4' wide machine < 1000syRI-130.00$ SYAC Grinding, 4' wide machine 1000-2000syRI-216.00$ SY101016,160.00AC Grinding, 4' wide machine > 2000syRI-310.00$ SYAC Removal/DisposalRI-435.00$ SY66023,100.00Barricade, Type III ( Permanent )RI-556.00$ LFGuard RailRI-630.00$ LFCurb & Gutter, rolledRI-717.00$ LFCurb & Gutter, verticalRI-812.50$ LF50625.00665083,125.00Curb and Gutter, demolition and disposalRI-918.00$ LF50900.00Curb, extruded asphaltRI-105.50$ LFCurb, extruded concreteRI-117.00$ LFSawcut, asphalt, 3" depthRI-121.85$ LF12402,294.00Sawcut, concrete, per 1" depthRI-133.00$ LFSealant, asphaltRI-142.00$ LFShoulder, gravel, 4" thickRI-1515.00$ SYSidewalk, 4" thickRI-1638.00$ SY25950.003690140,220.001505,700.00Sidewalk, 4" thick, demolition and disposalRI-1732.00$ SY25800.00Sidewalk, 5" thickRI-1841.00$ SYSidewalk, 5" thick, demolition and disposalRI-1940.00$ SYSign, Handicap RI-2085.00$ EachStriping, per stallRI-217.00$ EachStriping, thermoplastic, ( for crosswalk )RI-223.00$ SF270810.00Striping, 4" reflectorized lineRI-230.50$ LFAdditional 2.5" Crushed SurfacingRI-243.60$ SYHMA 1/2" Overlay 1.5" RI-2514.00$ SY101014,140.00HMA 1/2" Overlay 2"RI-2618.00$ SYHMA Road, 2", 4" rock, First 2500 SYRI-2728.00$ SYHMA Road, 2", 4" rock, Qty. over 2500SYRI-2821.00$ SYHMA Road, 4", 6" rock, First 2500 SYRI-2945.00$ SY2500112,500.0083037,350.00HMA Road, 4", 6" rock, Qty. over 2500 SYRI-3037.00$ SY6370235,690.00HMA Road, 4", 4.5" ATBRI-3138.00$ SYGravel Road, 4" rock, First 2500 SYRI-3215.00$ SYGravel Road, 4" rock, Qty. over 2500 SYRI-3310.00$ SYThickened EdgeRI-348.60$ LFSUBTOTAL THIS PAGE:59,779.00571,535.0043,050.00(B)(C)(D)(E)Page 5 of 14Ref 8-H Bond Quantity WorksheetSECTION II.b TRANSPORTATIONUnit Prices Updated: 06/14/2016Version: 06/14/2016Printed 12/5/2016 CED Permit #:U16006368ExistingFuture PublicPrivateRight-of-WayImprovementsImprovements(D) (E)DescriptionNo. Unit PriceUnitQuant.CostQuant.CostQuant.CostQuant.CostSITE IMPROVEMENT BOND QUANTITY WORKSHEETFOR STREET AND SITE IMPROVEMENTSQuantity Remaining (Bond Reduction) (B)(C)PARKING LOT SURFACINGNo.2" AC, 2" top course rock & 4" borrowPL-121.00$ SY2" AC, 1.5" top course & 2.5" base coursePL-228.00$ SY4" select borrowPL-35.00$ SY1.5" top course rock & 2.5" base coursePL-414.00$ SYSUBTOTAL PARKING LOT SURFACING:(B)(C)(D)(E)LANDSCAPING & VEGETATIONNo.Street TreesLA-1350.00$ EA9934,650.00Median LandscapingLA-2Right-of-Way LandscapingLA-3Wetland LandscapingLA-425,000.00$ LS125,000.00SUBTOTAL LANDSCAPING & VEGETATION:34,650.0025,000.00(B)(C)(D)(E)TRAFFIC & LIGHTINGNo.SignsTR-1350.00$ EA31,050.00279,450.00Street Light System ( # of Poles)TR-29,500.00$ EA52494,000.00Traffic SignalTR-3Traffic Signal ModificationTR-4SUBTOTAL TRAFFIC & LIGHTING:1,050.00503,450.00(B)(C)(D)(E)WRITE-IN-ITEMSSUBTOTAL WRITE-IN ITEMS:STREET AND SITE IMPROVEMENTS SUBTOTAL:60,829.001,422,935.002,398,425.74SALES TAX @ 9.5%5,778.76135,178.83227,850.45STREET AND SITE IMPROVEMENTS TOTAL:66,607.761,558,113.832,626,276.19(B)(C)(D)(E)Page 6 of 14Ref 8-H Bond Quantity WorksheetSECTION II.b TRANSPORTATIONUnit Prices Updated: 06/14/2016Version: 06/14/2016Printed 12/5/2016 CED Permit #:U16006368ExistingFuture PublicPrivateRight-of-WayImprovementsImprovements(D) (E)DescriptionNo. Unit PriceUnitQuant.CostQuant.CostQuant.CostQuant.CostDRAINAGE (CPE = Corrugated Polyethylene Pipe, N12 or Equivalent) For Culvert prices, Average of 4' cover was assumed. Assume perforated PVC is same price as solid pipe.) Access Road, R/DD-126.00$ SY* (CBs include frame and lid)BeehiveD-290.00$ Each2180.00Through-curb Inlet FrameworkD-3400.00$ EachCB Type ID-41,500.00$ Each2740,500.0011,500.00CB Type ILD-51,750.00$ Each11,750.0023,500.00CB Type II, 48" diameterD-62,300.00$ Each49,200.002250,600.0049,200.00 for additional depth over 4' D-7480.00$ FT2311,040.00218104,640.004622,080.00CB Type II, 54" diameterD-82,500.00$ Each410,000.0037,500.00 for additional depth over 4'D-9495.00$ FT6230,690.002813,860.00CB Type II, 60" diameterD-102,800.00$ Each for additional depth over 4'D-11600.00$ FTCB Type II, 72" diameterD-126,000.00$ Each for additional depth over 4'D-13850.00$ FTCB Type II, 96" diameterD-1414,000.00$ Each for additional depth over 4'D-15925.00$ FTTrash Rack, 12"D-16350.00$ Each1350.00Trash Rack, 15"D-17410.00$ EachTrash Rack, 18"D-18480.00$ EachTrash Rack, 21"D-19550.00$ EachCleanout, PVC, 4"D-20150.00$ EachCleanout, PVC, 6"D-21170.00$ Each16528,050.00Cleanout, PVC, 8"D-22200.00$ EachCulvert, PVC, 4" (Not allowed in ROW)D-2310.00$ LFCulvert, PVC, 6" (Not allowed in ROW)D-2413.00$ LFCulvert, PVC, 8" (Not allowed in ROW)D-2515.00$ LFCulvert, PVC, 12" (Not allowed in ROW)D-2623.00$ LFCulvert, PVC, 15" (Not allowed in ROW)D-2735.00$ LFCulvert, PVC, 18" (Not allowed in ROW)D-2841.00$ LFCulvert, PVC, 24" (Not allowed in ROW)D-2956.00$ LFCulvert, PVC, 30" (Not allowed in ROW)D-3078.00$ LFCulvert, PVC, 36" (Not allowed in ROW)D-31130.00$ LFCulvert, CMP, 8"D-3219.00$ LFCulvert, CMP, 12"D-3329.00$ LFSUBTOTAL THIS PAGE:20,240.00238,360.0086,040.00(B)(C)(D)(E)SITE IMPROVEMENT BOND QUANTITY WORKSHEETFOR DRAINAGE AND STORMWATER FACILITIESQuantity Remaining (Bond Reduction) (B)(C)Page 7 of 14Ref 8-H Bond Quantity WorksheetSECTION II.c DRAINAGEUnit Prices Updated: 06/14/2016Version: 06/14/2016Printed 12/5/2016 CED Permit #:U16006368ExistingFuture PublicPrivateRight-of-WayImprovementsImprovements(D) (E)DescriptionNo. Unit PriceUnitQuant.CostQuant.CostQuant.CostQuant.CostSITE IMPROVEMENT BOND QUANTITY WORKSHEETFOR DRAINAGE AND STORMWATER FACILITIESQuantity Remaining (Bond Reduction) (B)(C)DRAINAGE (Continued)Culvert, CMP, 15"D-3435.00$ LFCulvert, CMP, 18"D-3541.00$ LFCulvert, CMP, 24"D-3656.00$ LFCulvert, CMP, 30"D-3778.00$ LFCulvert, CMP, 36"D-38130.00$ LFCulvert, CMP, 48"D-39190.00$ LFCulvert, CMP, 60"D-40270.00$ LFCulvert, CMP, 72"D-41350.00$ LFCulvert, Concrete, 8"D-4242.00$ LFCulvert, Concrete, 12"D-4348.00$ LFCulvert, Concrete, 15"D-4478.00$ LFCulvert, Concrete, 18"D-4548.00$ LFCulvert, Concrete, 24"D-4678.00$ LFCulvert, Concrete, 30"D-47125.00$ LFCulvert, Concrete, 36"D-48150.00$ LFCulvert, Concrete, 42"D-49175.00$ LFCulvert, Concrete, 48"D-50205.00$ LFCulvert, CPE, 6" (Not allowed in ROW)D-5114.00$ LFCulvert, CPE, 8" (Not allowed in ROW)D-5216.00$ LFCulvert, CPE, 12" (Not allowed in ROW)D-5324.00$ LFCulvert, CPE, 15" (Not allowed in ROW)D-5435.00$ LFCulvert, CPE, 18" (Not allowed in ROW)D-5541.00$ LFCulvert, CPE, 24" (Not allowed in ROW)D-5656.00$ LFCulvert, CPE, 30" (Not allowed in ROW)D-5778.00$ LFCulvert, CPE, 36" (Not allowed in ROW)D-58130.00$ LFCulvert, LCPE, 6"D-5960.00$ LF5300318,000.00Culvert, LCPE, 8"D-6072.00$ LFCulvert, LCPE, 12"D-6184.00$ LF1857155,988.0012810,752.00Culvert, LCPE, 15"D-6296.00$ LFCulvert, LCPE, 18"D-63108.00$ LF57061,560.0061366,204.0046650,328.00Culvert, LCPE, 24"D-64120.00$ LF52763,240.00Culvert, LCPE, 30"D-65132.00$ LF41354,516.0045660,192.00Culvert, LCPE, 36"D-66144.00$ LFCulvert, LCPE, 48"D-67156.00$ LFCulvert, LCPE, 54"D-68168.00$ LFSUBTOTAL THIS PAGE:61,560.00339,948.00439,272.00(B)(C)(D)(E)Page 8 of 14Ref 8-H Bond Quantity WorksheetSECTION II.c DRAINAGEUnit Prices Updated: 06/14/2016Version: 06/14/2016Printed 12/5/2016 CED Permit #:U16006368ExistingFuture PublicPrivateRight-of-WayImprovementsImprovements(D) (E)DescriptionNo. Unit PriceUnitQuant.CostQuant.CostQuant.CostQuant.CostSITE IMPROVEMENT BOND QUANTITY WORKSHEETFOR DRAINAGE AND STORMWATER FACILITIESQuantity Remaining (Bond Reduction) (B)(C)DRAINAGE (Continued)Culvert, LCPE, 60"D-69180.00$ LFCulvert, LCPE, 72"D-70192.00$ LFCulvert, HDPE, 6"D-7142.00$ LFCulvert, HDPE, 8"D-7242.00$ LFCulvert, HDPE, 12"D-7374.00$ LFCulvert, HDPE, 15"D-74106.00$ LFCulvert, HDPE, 18"D-75138.00$ LFCulvert, HDPE, 24"D-76221.00$ LFCulvert, HDPE, 30"D-77276.00$ LFCulvert, HDPE, 36"D-78331.00$ LFCulvert, HDPE, 48"D-79386.00$ LFCulvert, HDPE, 54"D-80441.00$ LFCulvert, HDPE, 60"D-81496.00$ LFCulvert, HDPE, 72"D-82551.00$ LFPipe, Polypropylene, 6"D-8384.00$ LFPipe, Polypropylene, 8"D-8489.00$ LFPipe, Polypropylene, 12"D-8595.00$ LFPipe, Polypropylene, 15"D-86100.00$ LFPipe, Polypropylene, 18"D-87106.00$ LFPipe, Polypropylene, 24"D-88111.00$ LFPipe, Polypropylene, 30"D-89119.00$ LFPipe, Polypropylene, 36"D-90154.00$ LFPipe, Polypropylene, 48"D-91226.00$ LFPipe, Polypropylene, 54"D-92332.00$ LFPipe, Polypropylene, 60"D-93439.00$ LFPipe, Polypropylene, 72"D-94545.00$ LFCulvert, DI, 6"D-9561.00$ LFCulvert, DI, 8"D-9684.00$ LFCulvert, DI, 12"D-97106.00$ LF28930,634.00Culvert, DI, 15"D-98129.00$ LFCulvert, DI, 18"D-99152.00$ LFCulvert, DI, 24"D-100175.00$ LFCulvert, DI, 30"D-101198.00$ LFCulvert, DI, 36"D-102220.00$ LFCulvert, DI, 48"D-103243.00$ LFCulvert, DI, 54"D-104266.00$ LFCulvert, DI, 60"D-105289.00$ LFCulvert, DI, 72"D-106311.00$ LFSUBTOTAL THIS PAGE:30,634.00(B)(C)(D)(E)Page 9 of 14Ref 8-H Bond Quantity WorksheetSECTION II.c DRAINAGEUnit Prices Updated: 06/14/2016Version: 06/14/2016Printed 12/5/2016 CED Permit #:U16006368ExistingFuture PublicPrivateRight-of-WayImprovementsImprovements(D) (E)DescriptionNo. Unit PriceUnitQuant.CostQuant.CostQuant.CostQuant.CostSITE IMPROVEMENT BOND QUANTITY WORKSHEETFOR DRAINAGE AND STORMWATER FACILITIESQuantity Remaining (Bond Reduction) (B)(C)Specialty Drainage ItemsDitching SD-19.50$ CYFlow Dispersal Trench (1,436 base+)SD-328.00$ LF French Drain (3' depth)SD-426.00$ LFGeotextile, laid in trench, polypropyleneSD-53.00$ SYMid-tank Access Riser, 48" dia, 6' deepSD-62,000.00$ EachPond Overflow SpillwaySD-716.00$ SYRestrictor/Oil Separator, 12"SD-81,150.00$ EachRestrictor/Oil Separator, 15"SD-91,350.00$ EachRestrictor/Oil Separator, 18"SD-101,700.00$ Each23,400.00Riprap, placedSD-1142.00$ CYTank End Reducer (36" diameter)SD-121,200.00$ EachInfiltration pond testingSD-13125.00$ HRPermeable PavementSD-14Permeable Concrete SidewalkSD-15Culvert, Box __ ft x __ ftSD-16SUBTOTAL SPECIALTY DRAINAGE ITEMS:3,400.00(B)(C)(D)(E)STORMWATER FACILITIES (Include Flow Control and Water Quality Facility Summary Sheet and Sketch)Detention PondSF-1Each Detention TankSF-2Each Detention VaultSF-3###########Each 11,437,500.00Infiltration PondSF-4Each Infiltration TankSF-5Each Infiltration VaultSF-6Each Infiltration TrenchesSF-7Each Basic Biofiltration SwaleSF-8Each Wet Biofiltration SwaleSF-9Each WetpondSF-10Each WetvaultSF-11Each Sand FilterSF-12Each Sand Filter VaultSF-13Each Linear Sand FilterSF-14Each StormFilterSF-15130,000.00$ Each 1130,000.00Rain GardenSF-16Each SUBTOTAL STORMWATER FACILITIES:1,567,500.00(B)(C)(D)(E)Page 10 of 14Ref 8-H Bond Quantity WorksheetSECTION II.c DRAINAGEUnit Prices Updated: 06/14/2016Version: 06/14/2016Printed 12/5/2016 CED Permit #:U16006368ExistingFuture PublicPrivateRight-of-WayImprovementsImprovements(D) (E)DescriptionNo. Unit PriceUnitQuant.CostQuant.CostQuant.CostQuant.CostSITE IMPROVEMENT BOND QUANTITY WORKSHEETFOR DRAINAGE AND STORMWATER FACILITIESQuantity Remaining (Bond Reduction) (B)(C)WRITE-IN-ITEMSWI-1WI-2WI-3WI-4WI-5WI-6WI-7WI-8WI-9WI-10WI-11WI-12WI-13WI-14WI-15SUBTOTAL WRITE-IN ITEMS:DRAINAGE AND STORMWATER FACILITIES SUBTOTAL:81,800.00578,308.002,096,212.00SALES TAX @ 9.5%7,771.0054,939.26199,140.14DRAINAGE AND STORMWATER FACILITIES TOTAL:89,571.00633,247.262,295,352.14(B) (C) (D) (E)Page 11 of 14Ref 8-H Bond Quantity WorksheetSECTION II.c DRAINAGEUnit Prices Updated: 06/14/2016Version: 06/14/2016Printed 12/5/2016 CED Permit #:U16006368ExistingFuture PublicPrivateRight-of-WayImprovementsImprovements(D) (E)DescriptionNo. Unit PriceUnitQuant.CostQuant.CostQuant.CostQuant.CostConnection to Existing WatermainW-12,000.00$ Each12,000.0012,000.00Ductile Iron Watermain, CL 52, 4 Inch DiameterW-250.00$ LFDuctile Iron Watermain, CL 52, 6 Inch DiameterW-356.00$ LFDuctile Iron Watermain, CL 52, 8 Inch DiameterW-460.00$ LF3543212,580.00Ductile Iron Watermain, CL 52, 10 Inch DiameterW-570.00$ LFDuctile Iron Watermain, CL 52, 12 Inch DiameterW-680.00$ LFGate Valve, 4 inch DiameterW-7500.00$ EachGate Valve, 6 inch DiameterW-8700.00$ EachGate Valve, 8 Inch DiameterW-9800.00$ Each1310,400.00Gate Valve, 10 Inch DiameterW-101,000.00$ EachGate Valve, 12 Inch DiameterW-111,200.00$ EachFire Hydrant AssemblyW-124,000.00$ Each624,000.00Permanent Blow-Off AssemblyW-131,800.00$ Each23,600.00Air-Vac Assembly, 2-Inch DiameterW-142,000.00$ EachAir-Vac Assembly, 1-Inch DiameterW-151,500.00$ Each11,500.00Compound Meter Assembly 3-inch DiameterW-168,000.00$ EachCompound Meter Assembly 4-inch DiameterW-179,000.00$ EachCompound Meter Assembly 6-inch DiameterW-1810,000.00$ EachPressure Reducing Valve Station 8-inch to 10-inchW-1920,000.00$ EachWATER SUBTOTAL:2,000.00254,080.00SALES TAX @ 9.5%190.0024,137.60WATER TOTAL:2,190.00278,217.60(B) (C) (D) (E)SITE IMPROVEMENT BOND QUANTITY WORKSHEETFOR WATERQuantity Remaining (Bond Reduction) (B)(C)Page 12 of 14Ref 8-H Bond Quantity WorksheetSECTION II.d WATERUnit Prices Updated: 06/14/2016Version: 06/14/2016Printed 12/5/2016 CED Permit #:U16006368ExistingFuture PublicPrivateRight-of-WayImprovementsImprovements(D) (E)DescriptionNo. Unit PriceUnitQuant.CostQuant.CostQuant.CostQuant.CostClean OutsSS-11,000.00$ Each9696,000.00Grease Interceptor, 500 gallonSS-28,000.00$ EachGrease Interceptor, 1000 gallonSS-310,000.00$ EachGrease Interceptor, 1500 gallonSS-415,000.00$ EachSide Sewer Pipe, PVC. 4 Inch DiameterSS-580.00$ LFSide Sewer Pipe, PVC. 6 Inch DiameterSS-695.00$ LF4900465,500.00Sewer Pipe, PVC, 8 inch DiameterSS-7105.00$ LF3053320,565.0032033,600.00Sewer Pipe, PVC, 12 Inch DiameterSS-8120.00$ LFSewer Pipe, DI, 8 inch DiameterSS-9115.00$ LFSewer Pipe, DI, 12 Inch DiameterSS-10130.00$ LFManhole, 48 Inch DiameterSS-116,000.00$ Each22132,000.00318,000.00Manhole, 54 Inch DiameterSS-136,500.00$ EachManhole, 60 Inch DiameterSS-157,500.00$ EachManhole, 72 Inch DiameterSS-178,500.00$ EachManhole, 96 Inch DiameterSS-1914,000.00$ EachPipe, C-900, 12 Inch DiameterSS-21180.00$ LFOutside DropSS-241,500.00$ LSInside DropSS-251,000.00$ LSSewer Pipe, PVC, ____ Inch DiameterSS-26Lift Station (Entire System)SS-27LSSANITARY SEWER SUBTOTAL:452,565.00613,100.00SALES TAX @ 9.5%42,993.6858,244.50SANITARY SEWER TOTAL:495,558.68671,344.50(B) (C) (D) (E)SITE IMPROVEMENT BOND QUANTITY WORKSHEETFOR SANITARY SEWERQuantity Remaining (Bond Reduction) (B)(C)Page 13 of 14Ref 8-H Bond Quantity WorksheetSECTION II.e SANITARY SEWERUnit Prices Updated: 06/14/2016Version: 06/14/2016Printed 12/5/2016 Planning Division |1055 South Grady Way – 6th Floor | Renton, WA 98057 (425) 430-7200Date:Name:Project Name: PE Registration No:CED Plan # (LUA):Firm Name:CED Permit # (U):Firm Address:Site Address:Phone No.Parcel #(s):Email Address:Project Phase: Site Restoration/Erosion Sediment Control Subtotal (a)(a)119,041.83$ Existing Right-of-Way Improvements Subtotal (b)(b)68,797.76$ Future Public Improvements Subtotal(c)(c)2,331,890.10$ Stormwater & Drainage Facilities Subtotal (d)(d)3,018,170.40$ Bond Reduction (Quantity Remaining)2(e)(e)-$ Site RestorationCivil Construction PermitMaintenance Bond1,083,771.65$ Bond Reduction2Construction Permit Bond Amount 3Minimum Bond Amount is $10,000.001 Estimate Only - May involve multiple and variable components, which will be established on an individual basis by Development Engineering.2 The City of Renton allows one request only for bond reduction prior to the maintenance period. Reduction of not more than 70% of the original bond amount, provided that the remaining 30% willcover all remaining items to be constructed. 3 Required Bond Amounts are subject to review and modification by Development Engineering.* Note: The word BOND as used in this document means any financial guarantee acceptable to the City of Renton.** Note: All prices include labor, equipment, materials, overhead and profit. T(P +R - S)Prepared by:Project InformationCONSTRUCTION BOND AMOUNT */**(prior to permit issuance)(425) 251-6222btalkington@barghausen.comAllura at Tiffany park S.E. 18th Street and 124th Place S.E.See BelowFOR APPROVALU1600636818215 72nd Avenue South8,306,850.13$ P (a) x 150%SITE IMPROVEMENT BOND QUANTITY WORKSHEET BOND CALCULATIONS12/5/2016Barry J Talkington41423Barghausen Consulting Engineers, Inc.R((b)+(c)+(d)) x 150%EST1((b) + (c) + (d)) x 20%-$ MAINTENANCE BOND */**(after final acceptance of construction)119,041.83$ 68,797.76$ 8,128,287.38$ 178,562.75$ -$ 2,331,890.10$ 3,018,170.40$ S(e) x 150%Page 14 of 14Ref 8-H Bond Quantity WorksheetSECTION III. BOND WORKSHEETUnit Prices Updated: 06/14/2016Version: 06/14/2016Printed 12/5/2016 Facility Summary Form9.2 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL 2009 Surface Water Design Manual 1/9/2009 1 STORMWATER FACILITY SUMMARY SHEET DDES Permit Number__________________ (provide one Stormwater Facility Summary Sheet per Natural Discharge Location) Overview: Project Name _______________________________________________________Date___________________ Downstream Drainage Basins Major Basin Name _____________________________ Immediate Basin Name __________________________ Flow Control: Flow Control Facility Name/Number ________________________________ Facility Location________________________________________________________________________ ___ If none, Flow control provided in regional/shared facility (give location)___________________________________ No flow control required_____________ Exemption number _______________________________ General Facility Information: Type/Number of detention facilities: Type/Number of infiltration facilities: ______ ponds ______ ponds ______ vaults ______ tanks ______ tanks ______ trenches Control Structure Location _____________________________________________________________________ Type of Control Structure ______________________________ Number of Orifices/Restrictions _____________ Size of Orifice/Restriction: No. 1 ________________ No. 2 ________________ No. 3 ________________ No. 4 ________________ Flow Control Performance Standard _________________________________ Allura at Tiffany Park 11/11/16 Cedar River Ginger Creek Tract A N/A N/A N/A 1 Tract A (Inside Detention Vault) Dual Orifice Restrictor 2.50 in 3.90 in Flow Control Duration Standard Matching Forested Site Conditions 16055-F-StormWATR Facility Summary-KC-2016-11-11 KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL 2009 Surface Water Design Manual 1/9/2009 2 Live Storage Volume __________________ Depth _______________ Volume Factor of Safety ________________ Number of Acres Served ____________________ Number of Lots ____________________ Dam Safety Regulations (Washington State Department of Ecology) Reservoir Volume above natural grade ________________ Depth of Reservoir above natural grade _______________ Facility Summary Sheet Sketch All detention, infiltration and water quality facilities must include a detailed sketch. (11"x17" reduced size plan sheets may be used) 229,130 cf 11 ft 24.48 Acres 94 0 cf 0 ft KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL 2009 Surface Water Design Manual 1/9/2009 3 Water Quality: Type/Number of water quality facilities/BMPs: ______ biofiltration swale ______ sand filter (basic or large) (regular/wet/ or continuous inflow) ______ sand filter, linear (basic or large) ______ combined detention/wetpond ______ sand filter vault (basic or large) (wetpond portion basic or large) sand bed depth______ (inches) ______ combined detention/wetvault ______ stormwater wetland ______ filter strip ______ storm filter ______ flow dispersion ______ wetpond (basic or large) ______ farm management plan ______ wetvault ______ landscape management plan ______ Is facility Lined? ______ oil/water separator If so, what marker is used above (baffle or coalescing plate) Liner?____________________ ______ catch basin inserts: Manufacturer____________________________________________ ______ pre-settling pond ______ pre-settling structure: Manufacturer__________________________________________ ______ high flow bypass structure (e.g., flow-splitter catch basin) ______ source controls _________________________________________________________ Design Information Water Quality design flow ______________________________ Water Quality treated volume (sandfilter) ___________________ Water Quality storage volume (wetpool) ___________________ Facility Summary Sheet Sketch 1 0.47 cfs KING COUNTY, WASHINGTON, SURFACE WATER DESIGN MANUAL 2009 Surface Water Design Manual 1/9/2009 4 All detention, infiltration and water quality facilities must include a detailed sketch. (11"x17" reduced size plan sheets may be used) ALLURA AT TIFFANY PARK ALLURA AT TIFFANY PARKTED-40-39235/4/17 ALLURA AT TIFFANY PARK ALLURA AT TIFFANY PARKTED-40-39235/4/17 ALLURA AT TIFFANY PARK ALLURA AT TIFFANY PARKTED-40-39235/4/17 800-338-1122 513-645-7000 513-645-7993 FAX 9025 Centre Pointe Dr., Suite 400, West Chester, OH 45069 SF0822 STORMFILTER STANDARD DETAILTHIS PRODUCT MAY BE PROTECTED BY ONE OR MORE OF THE FOLLOWING U.S. PATENTS: 5,322,629; 5,524,576; 5,707,527; 5,985,157; 6,027,639; 6,649,048; RELATED FOREIGN PATENTS, OR OTHER PATENTS PENDING. STORMFILTER TREATMENT CAPACITY IS A FUNCTION OF THE CARTRIDGE SELECTION AND THE NUMBER OF CARTRIDGES. THE STANDARD VAULT STYLE IS SHOWN WITH THE MAXIMUM NUMBER OF CARTRIDGES (56). VAULT STYLE OPTIONS INCLUDE INLET BAY (49), INLET BAY/OUTLET BAY (46), OUTLET BAY (51), NLET BAY/FULL HEIGHT BAFFLE WALL (41), FULL HEIGHT BAFFLE WALL (46). STORMFILTER 8X22 PEAK HYDRAULIC CAPACITY IS 1.8 CFS. IF THE SITE CONDITIONS EXCEED 1.8 CFS AN UPSTREAM BYPASS STRUCTURE IS REQUIRED. FOR M AINTENANCE CA L L 1.8 0 0 .3 3 8 .1122 C le a n w a t e r s t ar ts here GENERAL NOTES 1.CONTECH TO PROVIDE ALL MATERIALS UNLESS NOTED OTHERWISE. 2.DIMENSIONS MARKED WITH ( ) ARE REFERENCE DIMENSIONS. ACTUAL DIMENSIONS MAY VARY. 3.FOR SITE SPECIFIC DRAWINGS WITH DETAILED VAULT DIMENSIONS AND WEIGHTS, PLEASE CONTACT YOUR CONTECH ENGINEERED SOLUTIONS LLC REPRESENTATIVE. www.ContechES.com 4.STORMFILTER WATER QUALITY STRUCTURE SHALL BE IN ACCORDANCE WITH ALL DESIGN DATA AND INFORMATION CONTAINED IN THIS DRAWING. 5.STRUCTURE SHALL MEET AASHTO HS20 LOAD RATING, ASSUMING EARTH COVER OF 0' - 5' AND GROUNDWATER ELEVATION AT, OR BELOW, THE OUTLET PIPE INVERT ELEVATION. ENGINEER OF RECORD TO CONFIRM ACTUAL GROUNDWATER ELEVATION. CASTINGS SHALL MEET AASHTO M306 AND BE CAST WITH THE CONTECH LOGO. 6.FILTER CARTRIDGES SHALL BE MEDIA-FILLED, PASSIVE, SIPHON ACTUATED, RADIAL FLOW, AND SELF CLEANING. RADIAL MEDIA DEPTH SHALL BE 7-INCHES. FILTER MEDIA CONTACT TIME SHALL BE AT LEAST 38 SECONDS. 7.SPECIFIC FLOW RATE IS EQUAL TO THE FILTER TREATMENT CAPACITY (gpm) DIVIDED BY THE FILTER CONTACT SURFACE AREA (sq ft). 8.STORMFILTER STRUCTURE SHALL BE PRECAST CONFORMING TO ASTM C-857 AND AASHTO LOAD FACTOR DESIGN METHOD. INSTALLATION NOTES A.ANY SUB-BASE, BACKFILL DEPTH, AND/OR ANTI-FLOTATION PROVISIONS ARE SITE-SPECIFIC DESIGN CONSIDERATIONS AND SHALL BE SPECIFIED BY ENGINEER OF RECORD. B.CONTRACTOR TO PROVIDE EQUIPMENT WITH SUFFICIENT LIFTING AND REACH CAPACITY TO LIFT AND SET THE STORMFILTER VAULT (LIFTING CLUTCHES PROVIDED). C.CONTRACTOR TO INSTALL JOINT SEALANT BETWEEN ALL VAULT SECTIONS AND ASSEMBLE VAULT. D.CONTRACTOR TO PROVIDE, INSTALL, AND GROUT PIPES. MATCH OUTLET PIPE INVERT WITH OUTLET BAY FLOOR. E.CONTRACTOR TO TAKE APPROPRIATE MEASURES TO PROTECT CARTRIDGES FROM CONSTRUCTION-RELATED EROSION RUNOFF. STORMFILTER DESIGN NOTES CARTRIDGE HEIGHT SPECIFIC FLOW RATE (gpm/sf) CARTRIDGE FLOW RATE (gpm) RECOMMENDED HYDRAULIC DROP (H) 27"18"LOW DROP 3.05'2.3'1.8' CARTRIDGE SELECTION 18.79 12.53 8.35 2 gpm/sf 22.5 11.25 15 10 57.5 1.67* gpm/sf 1 gpm/sf 2 gpm/sf 1.67* gpm/sf 1 gpm/sf 2 gpm/sf 1.67* gpm/sf 1 gpm/sf * 1.67 gpm/sf SPECIFIC FLOW RATE IS APPROVED WITH PHOSPHOSORB® (PSORB) MEDIA ONLY HYDRAULIC DROP(H) INLET INV.TO OUTLET INV.INSIDE VAULT HEIGHT6' TYPICALSECTION A-A OUTLET PIPE OVERFLOW ASSEMBLY GRADE RING/RISERS INLET DISSIPATOR INLET PIPE CONTRACTOR TO GROUT TO FINISHED GRADE STORMFILTER CARTRIDGE FLOW KIT STEP OUTLETINLET PLAN VIEW VAULT STYLE: OUTLET SUMP (NIB) INLET DISSIPATOR (9'-3") OUTLET SUMP 2'-0"A A (2'-0") STORMFILTER CARTRIDGE 22'-0"8'-0"ALTERNATE PIPE LOCATION (TYP) 6" CONCRETE WALL WIDTH MAY VARY REGIONALLY ** STRUCTURE ID WATER QUALITY FLOW RATE (cfs) PEAK FLOW RATE (cfs) RETURN PERIOD OF PEAK FLOW (yrs) NUMBER OF CARTRIDGES REQUIRED MEDIA TYPE (PERLITE, ZPG, PSORB) PIPE DATA:I.E.MATERIAL DIAMETER INLET PIPE #1 INLET PIPE #2 OUTLET PIPE SITE SPECIFIC DATA REQUIREMENTS WIDTH HEIGHTANTI-FLOTATION BALLAST NOTES/SPECIAL REQUIREMENTS: DOWNSTREAM RIM ELEVATION CARTRIDGE FLOW RATE (gpm/f) * PER ENGINEER OF RECORD CARTRIDGE HEIGHT (27", 18", LOW DROP(LD)) UPSTREAM RIM ELEVATION ** 402.5 18"CPEP384.60 18"CPEP386.90 ZPG 1.00 53 100 5.53 0.47 SF#1 18" 402.5 ALLURA AT TIFFANY PARK ALLURA AT TIFFANY PARKTED-40-39235/4/17 ALLURA AT TIFFANY PARK ALLURA AT TIFFANY PARKTED-40-39235/4/17 Tab 10.0 16055.016.doc 10.0 OPERATIONS AND MAINTENANCE MANUAL Allura at Tiffany Park has a single Detention Vault and a Contech StormFilter vault located within Tract A of the proposed plat. Maintenance of these facilities shall be the responsibility of the individual lot owners within the project development. The onsite conveyance system consists of a series of catch basins and storm pipes which direct stormwater to the drainage facilities within Tract A. Onsite Conveyance Systems within the right of way will be inspected and maintained by the City of Renton. Onsite conveyance systems within the drainage easements or tracts will be maintained by the property owners through the Homeowners' Association created by the subdivision (with each property owner having equal responsibility for maintenance). These conveyance elements include those entering and exiting the tract from/to the public right-of-way. For conveyance pipes entering the tract from right-of-way, responsibility begins at the last structure prior to entering the tract. For conveyance pipes exiting the tract to right-of-way, responsibility ends at the next downstream structure. The easement shall grant the City rights for inspection. Maintenance of the above listed stormwater facilities shall be conducted on an annual basis. Please refer to the maintenance requirements within this section. Tab 11.0 Appendix A