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Incomplete Prelim Drain & Erosion Control1 BEEHIVE M GEMENT ROUP, INC. EASTH VEN VILLA ADDITION 311 CULL S ROAD, NORTHWEST YELM, WA 98597 DRAIN~GE AND EROSION CONTROL PRELIMINARY REPORT ~'1 _ ,\ ~/ ~ .~ ~ ,, 11, 2002 Easthaven Assisted Care Facility Addition Yelm WA PRELIMINARY REPORT PROJECT INFORMATION Project: Easthaven Assisted Caze Facility Addition Prepared: 7-10-02 Prepared For: Easthaven Villa, LLC 311 Cullens Road NW Yelm, WA 98597 360-866-1263 Contact: Marvin Pratt REVIEWING AGENCY Jurisdiction: City of Yelm Project Number: [] Project Contact: Dave Gibson PROJECT ENGINEER Prepared By: MC Squazed, Inc. 1235 E. 4`h Avenue Suite 101 Olympia, WA 98506 PH.360-754-9339 FAX 360-352-2044 Project Contact: Mazk J. Leingang, PE Project Number: 22234-C File Name/Number: m:projects/falter azchitecture/easthaven/documents PROJECT ENGINEER'S CERTIFICATION I hereby certify that this Preliminary Drainage Report for the Easthaven Assisted Caze Facility Addition in Yelm, WA has been prepared by me or under by supervision and meets the intent of the City of Yelm Development Guidelines unless noted otherwise, and normal standards of engineering practice. I understand that the City of Yelm does not and will not assume liability for the sufficiency, suitability, or performance of drainage facilities designed for this development. MC Squared,lnc. 7/11/02 E7~IRFS 1 Easthaven Assisted Care Facility Addition Yelm WA PRELIMINARY REPORT Table of Contents Part / Drainage Report SECTION 1 - EXISTING CONDITIONS 3 SECTION 2 - PROJECT DESCRIPTION q SECTION 3 - INFILTRATION RATES/SOILS REPORT 6 SECTION 4 - WELLS & SEPTIC SYSTEMS 6 SECTION 5 - FUEL TANKS 6 SECTION 6 - SUB-BASIN DESCRIPTION 6 SECTION 7 - ANALYSIS OF 100-YEAR FLOOD ~ SECTION 8 - AESTHETIC CONSIDERATIONS FOR STORMWATER FACILITIES 7 SECTION 9 - DOWNSTREAM CONSIDERATIONS ~ SECTION 10 - COVENANTS, DEDICATIONS, EASEMENTS 7 SECTION 11 - PROPERTY OWNERS ASSOCIATION ARTICLES OF INCORPORATION 7 Part 7l Erosion Controt Report SECTION 1 - CONSTRUCTION SEQUENCE AND PROCEDURE g SECTION 2 - TRAPPING SEDIMENT g SECTION 3 - PERMANENT EROSION CONTROL & SITE RESTORATION 9 SECTION 4 - GEOTECHNICAL ANALYSIS AND REPORT 9 SECTION 5 - INSPECTION SEQUENCE q SECTION 6 - CONTROL OF POLLUTANTS OTHER TRAN SEDIMENTS 10 Part /II Maintenance Ptan SECTION 1 - REQUIRED MAINTENANCE 13 SECTION 2 - RESPONSIBLE ORGANIZATION x SECTION 3 - VEGETATION MANAGEMENT PLAN x SECTION 4 - SOURCE CONTROL x Appendices Appendix I Drainage Calculations Appendix II Soils ReporUSCS Soils Map and Description Appendix III Vicinity Map Appendix IV STORMFILTERO Product/Maintenance Information Appendix V Thurston County Geodata Query Results (Excerpt) Appendix VI Prelimary Drainage and Erosion Control Plan MC Squared, Inc. 2 7111/02 Easthaven Assisted Care Facility Addition Yelm WA PRELIMINARY REPORT The format of this report follows the outline provided in the Drainage Design and Erosion Control Manual (DDECM) for Thurston County. DOE Standazds have been used for the design, however. SECTION 1 -EXISTING CONDITIONS The 0.61-acre site is located within the City of Yelm, immediately southwest of the existing Easthaven Villa Site. The site is currently used for growing Christmas trees and has recently been surveyed for this addition. There is no significant off-site flow tributary to the site; a minor portion of the land to the west gently slopes to the site, and surface water can be assumed to sheet flow onto the property. The amount of surface water is limited however because the soils aze very well drained gravels and sands. Soils on site aze Spanaway gravelly sandy loam according to the Thurston County Soil Survey published by the Soils Conservation Service. There is an existing pond that serves as an infiltration facility for the existing assisted living facility. It is not adequately sized to handle the addition. The conveyance system to the pond will not handle the additional flows from the new addition. A new system will be designed. The project site is located in an aquifer sensitive azea. We will need to provide treatment of the runoff prior to infiltration. This project will comply with the intent of the stormwater treatment requirements of the City of Yelm development guidelines. MC Squared, Inc. 7/11 /02 Easthaven Assisted Care Facility Addition, Yelm, WA PRELIMINARY REPORT SECTION 2 -PROJECT DESCRIPTION Project Proponent: Easthaven Villa, LLC 311 Cullens Road NW Yelm, WA 98597 Marvin Pratt 503-357-3793 Total Project Area: ±0.61 Acres Site Address: 311 Cullens Road NW Yelm, WA 98597 Required Permits: Grading, utility, paving, building, plumbing, mechanical, electrical, etc. Sec/Township/Range: NE'/< Section 24, Township 17 North, Range 1 East, W.M., Thurston County, WA Zoning: Commercial The proponent proposes to add a 12,600 sf addition to an existing assisted caze facility and pazking for approximately 11 cars- Frontage improvements on Cullens Road aze to be included for this project. The owner proposes to add a stormwater system for collection, conveyance, treatment and dischazge of runoff to an underground infiltration gallery in the new drive on the developed project site. The system will be enhanced to accommodate landscape islands and new drain lines for roof and courtyazd runoff. Site development will be constructed in two phases. The first phase will include erosion control measures, site cleazing, and demolition of asphalt, grading, storm drainage improvements, and underground utilities such as power, cable, water, sewer and telecommunications. The second phase will include construction of the building, paving, site concrete work, landscaping, pavement restoration, seal coating, and striping. Site development will increase the total impervious area. Currently, small trees, with trunk diameter less than 12 inches, cover the entire site. Development will include creation of approximately 0.22 acres of access road and parking, which is treatable impervious surface. . There will be approximately 0.10 acres of perimeter landscaping, and building azea landscaping. The building will add approximately 0.29 acres of clean impervious surface. This will increase the site's impervious azea to approximately 0.51 acres. MC Squared, Inc. 4 7/11 /02 Easthaven Assisted Care Facility Addition. Yelm WA PRELIMINARY REPORT Development Coverage Summary Impervious Roof Area: Impervious Paved/Concrete Area: Landscaped or Pervious Area: Totals Existing Proposed 0 ac ±0.29 ac 0 ac ±0.22ac 0.61 ac ±0.10 ac ±0.61 ac ±0.61 ac A. Stormwater Treatment The effect of lack of relief, lack of azea and tight setbacks combine to eliminate several treatment BMPs; the following systems have been considered for this site: Bioswale Option: The proposed site layout and lack of topographic relief across The site makes it difficult to achieve significant success with biofiltration swales or filter strips. This BMP was not explored for the project. Wet Pond Option: This is not a feasible treatment measure for this site, because a suitable area is not available to accommodate the pond's 3-foot permanent pool depth, 3:1 length to width ratio, 3:1 side slopes, and the depth required for site drainage. This BMP was not explored for the project. StormfilterOOption: This product, distributed by Stormwater Management, Inc. is an appropriate treatment BMP for this project. A single Stormfilter0 catch basin CBSF-3-SD unit would treat the 6-month flow rate of 0.20 cfs. The unit could be placed in-line with the proposed 8-inch storm drain, just upstream infiltration gallery. Preferred Treatment Alternative: After considering the treatment options above, we have determined that the best option is the Stormfilter0 option. We recommend this to City of Yelm staff as the most practical and environmentally beneficial option. B. Stormwater Storage: Due to the excessively drained soils, the infiltration gallery will be sized to serve as both detention and disposal. Both will occur on site. All stormwater runoff will be infiltrated on site. There will not be a release offsite. C. Roof Runoff: MC Squared, Inc. 7/11 /02 Easthaven Assisted Care Facility Addition, Yelm, WA PRELIMINARY REPORT Roof runoff from the proposed addition will be tight lined to drywells for infiltration. The roof leaders will not be combined with the proposed pazking/asphalt treatable infiltration system. D. Landscape Area: In general, parking lot landscape azea runoff will sheet flow to driveway and pazking azeas for collection in the site's stonnwater system. Some azeas adjacent to the buildings will require yazd drains to collect runoff for dischazge to the drywell system mentioned above for roof drains. SECTION 3 -INFILTRATION RATES/SOILS REPORT The Soil Conservation Service (SCS) soil survey of Thurston County classifies the onsite soils as "Spanaway Gravelly Sandy Loam, 0 to 3 percent slopes". A typical soil profile is described by SCS as follows: "These deep, somewhat excessively drained soils aze on terraces. It formed in glacial outwash and volcanic ash. For the SCS soils description and map, see Appendix II. SECTION 4 -WELLS & SEPTIC SYSTEMS The owner is not awaze of any abandoned or existing wells on-site. Water service for the proposed project will be provided by the City of Yelm. The existing building has a STEP system that serves its sanitary sewer needs. No abandoned or existing septic systems were identified on-site for the property utilized for the addition during MC Squazed, Inc.'s site investigation. The additions sanitary sewer will be handled by a STEP system. Sewer service will be provided by the City of Yelm. SECTION 5 -FUEL TANKS No fuel tanks were located during our site inspection. The owner is not awaze of any existing tanks in the project azea. SECTION 6 -SUB-BASIN DESCRIPTION The site is situated within the City of Yelm commercial district. A minor amount of off-site runoff from the west is tributary to the site. However, given the permeable soil, any runoff from the west is assumed to be negligible. The other existing drainage conditions and systems aze detailed in Section 1 -Existing Conditions and is shown on Sheet C- 2 ofthe project civil engineering drawings, (enclosed in Appendix I). MC Squared, Inc. 7/11 /02 Easthaven Assisted Care Facility Addition. Yelm WA PRELIMINARY REPORT No hazardous materials aze expected to be handled or transported within the site other than cleaning/maintenance products associated with janitorial operations. SECTION 7 -ANALYSIS OF 100-YEAR FLOOD The FEMA FIRM Panel indicates the site is not in a 100-yeaz flood hazard azea. SECTION 8 -AESTHETIC CONSIDERATIONS FOR STORMWATER FACILITIES All pervious azeas will be vegetated and landscaped to provide an aesthetically pleasing environment per the requirements of the City. Landscaping plans have been prepazed by the landscape azchitectural design firm of [to be determined] SECTION 9 -DOWNSTREAM CONSIDERATIONS Runoff from the site will be infiltrated on site. There are not any downstream impacts anticipated. SECTION 10 -COVENANTS, DEDICATIONS, EASEMENTS On-site storm lines, catch basins, and roof drains will require routine maintenance. A maintenance schedule is included in Part III of this report. The owner's maintenance crews will maintain parking lot storm piping systems and catch basins. The building owners will maintain building roof drain lines. SECTION 11 -PROPERTY OWNERS ASSOCIATION ARTICLES OF INCORPORATION In light of the commercial nature of this project, special covenants covering landscape, maintenance, signage, stormwater and site maintenance will not be applicable. The building owner will perform maintenance of storm drainage facilities. The building owners will perform maintenance of the roof drain lines and courtyazd drains adjacent to the building. MC Squared,lnc. 7 7/11 /02 Easthaven Assisted Care Facility Addition, Yelm, WA PRELIMINARY REPORT SECTION 1 -CONSTRUCTION SEQUENCE AND PROCEDURE Development of the property will include site grading and erosion control measures designed to contain silt and soil within the project boundaries during construction until permanent erosion control is in place. Erosion/sedimentation control will be achieved by a combination of structurallvegetative cover measures and construction practices tailored to fit the site. Best Construction Management Practices (BMPs) will be employed to properly demolish, clear and grade the site and to schedule construction activities. Before any construction begins on-site, erosion control facilities shall first be installed. The contractor shall refer to the erosion control plans. The planned construction sequence is as follows: 1. Schedule preconstruction meeting with City. 2. Install temporary gravel construction entrance (as needed). 3. Install inlet protection for existing catch basins per Thurston County DDECM details 38 and 139 as shown on civil plans. 4. Install filter fabric fence (as needed). 5. Perform asphalt demolition, clearing, earthwork operations, and foundation excavation. 6. Install storm drainage improvements; install or relocate other utility lines. 7. Install inlet protection for all new on-site catch basins. 8. Hydroseed or cover all exposed areas subject to erosion, i.e., steep slopes, landscape islands, etc. 9. Designate an area for washing of equipment and concrete trucks to control wash down runoff and eliminate entry into storm drainage systems. 10. Complete building and site improvements. 11. Remove temporary erosion control facilities once site landscaping is stabilized. SECTION 2 -TRAPPING SEDIMENT The on-site soils belong to the Spanaway soil group and have slight erosion potential according to the SCS. If necessary, a stabilized construction entrance shall be installed at a single entry point to the site to prevent vehicles from tracking soil away from the disturbed areas. If sediment is tracked off-site, sediment shall, on a daily basis, be swept or shoveled from paved surfaces and not washed into the storm system. Unless the City inspector approves otherwise, the contractor shall not be allowed to leave disturbed areas greater than 5,000 sf, that are to be left unworked for more than 30 days uncovered during the rainy season from November 1 through March 31. Mulch, sodding or plastic covering will be used to prevent erosion in these areas. MC Squared, Inc. 7/11/02 Easthaven Assisted Care Facility Addition. Yelm WA PRELIMINARY REPORT During construction, the contractor may also be required to install filter fabric fencing, as needed, and/or as directed by the engineer, or city inspector. SECTION 3 -PERMANENT EROSION CONTROL & SITE RESTORATION All disturbed azeas will be paved, covered with a building or landscaped with ground cover, shrubbery or trees. SECTION 4 - GEOTECHNICAL ANALYSIS AND REPORT A geo-technical engineering study was not prepazed to address site work issues. No on- site slopes exceed 15%. An infiltration test is pending for stormwater infiltration system design. SECTION 5 -INSPECTION SEQUENCE In addition to the normal City inspections, the Project Engineer shall inspect the facilities related to stormwater treatment, erosion control, storage and conveyance during construction. At a minimum, the following items shall be inspected at the time specified: The erosion control facilities shall be inspected before the start of cleazing and grading to ensure the following structures are in place: a. Construction Entrance (if installed) b. Filter Fabric Fences (if installed) c. Catch Basin Inlet Protection 2. The conveyance systems shall be inspected after construction of the facility, but before the project is completed to ensure the following are in working order: a. Pazking Lot Surface Drainage b. Storm Lines, Catch Basins and Yazd Drains The permanent site restoration measures shall be inspected after landscaping is completed. A final inspection shall be performed to verify final grades, setting of control structures and all necessary information to complete Thurston County's Engineer's Construction Inspection Report Form and Commercial Agreement To Maintain Stormwater Facilities. These documents must be completed prior to final City construction approval. MC Squared, Inc. 7/11/02 Easthaven Assisted Care Facility Addition Yelm WA PRELIMINARY REPORT SECTION 6 -CONTROL OF POLLUTANTS OTHER THAN SEDIMENTS Washout from concrete trucks shall not be dumped into the storm drain, or onto soil or pavement, which carries stormwater runoff. It can be dumped into a designated azea to be later backfilled or hazdened and broken up for disposal into a dumpster. The Contractor will be required to designate a wash down azea for equipment and concrete trucks. MC Squared, Inc. 10 7/11!02 Easthaven Assisted Care Facility Addition. Yelm, WA PRELIMINARY REPORT INSTRUCTIONS The following pages contain maintenance needs for most of the components that aze part of the site drainage system. Advise the City of Yelm if there aze any components that aze missing from these pages. Ignore the requirements that do not apply to the system. Plan to complete a checklist for all system components on the following schedule: 1) Monthly from November through April. 2) Once in late summer (preferable September). 3) After any major storm (use "1" in 24 hours as a guideline). Using photocopies of these pages, check off the problems you looked for each time an inspection was performed. Add comments on problems found and actions taken. Keep these "checked" sheets in your files, as they will be used to write your annual report (due in May). Some items do not need to be looked at every time an inspection is done. Use the suggested frequency at the left of each item as a guideline for your inspection. Call the City for technical assistance if needed. MC Squared, Inc. 11 7111 /02 Easthaven Assisted Care Facility Addition. Yelm, WA PRELIMINARY REPORT MAINTENANCE PROGRAM COVER SHEET Inspection-Period: Number of Sheets Attached: Date Inspected: Name of Inspector: Inspector's Signature: MC Squared, Inc. 12 7/11 /02 Easthaven Assisted Care Facility Addition Yelm WA PRELIMINARY REPORT SECTION 1- REQUIRED MAINTENANCE The drainage facilities will require occasional maintenance. The following general requirements aze the minimum requirements as set forth in the Drainage Design and Erosion Control Manual of Thurston County. The required maintenance for storm drainage facilities and frequency of maintenance aze as follows: Maintenance Checklist for Conveyance Systems (Pipes and Swales) MC Squared, Inc. 13 7/11 /02 APPENDIX 1 DRAINAGE CALCULATIONS ~L`N ,~ r n/~ APPENDIX 11 BRADLEY-NOBLE SOILS/INFILTRATION REPORT APPENDIX 111 VICINITY MAP miles ~_ _. ° s 1 0 metersa .SOU.. 1000 , 7500 , 2040 APPENDIX IV STORMFILTER CBSF-3-SD PRODUCT AND MAINTENANCE INFORMATION E7ut~ ia~lC APPENDIX V THURSTON COUNTY GEODATA QUERY RESULTS EXCERPTS APPENDIX VI PRELIMINARY DRAINAGE AND EROSION CONTROL PLAN