Loading...
The URL can be used to link to this page
Your browser does not support the video tag.
Home
My WebLink
About
Stormwater and Erosion/Sediment Control - PLN General - 7/27/2006
0�N STATFO� MASON COUNTY �P MC PUBLIC WORKS DIRECTOR/COUNTY ROAD ENGINEER N Shelton, Washington 98584 r27 N Y O y TO BE KEG' o � T IN THE '864 DATE: July 27, 2006 PARCEL FILE INTER-DEPARTMENTAL COMMUNICATIONS TO: Kell McAboy PARCEL # 32135-33-00000 FROM: John Sliva, Programs Engineer-PW BUILDING PERMIT NUMBER: BLD2006-01091 SUBJECT: Stormwater Drainage Review NAME: O'Day Michael Kell, The Stormwater and Erosion/Sediment Control Plan for the proposed new Equestrian Riding Arena at 4771 E SR3 near Shelton has been received and reviewed by Public Works. The plan addresses the runoff from the new structure and the associated area. The stormwater system will be comprised of 3 shallow infiltration trenches that run along three sides of the arena. Roof runoff that is not infiltrated while in the trench will be directed to a final infiltration trench that is constructed with a level top. The last trench will allow remaining runoff to fill the trench and spill uniformly out of the trench and sheet flow into the near by forest. The author of he report indicates the calculated runoff entering the trees will be less than the calculated undeveloped runoff and will satisfy stream bank and erosion control requirements. Erosion control features during construction were also addressed. Based on the contents of this report, the Stormwater and Erosion/Sediment Control Site Plan was found to be satisfactory. I recommend accepting this report as satisfying the County's requirements for a stormwater site plan. An Operation and Maintenance covenant will not be required. Recommendations and comments contained in the report should be incorporated into the site development plans and made conditions for permit issuance. Adequate erosion and sediment control features need to be implemented during land disturbing activities to protect neighboring properties and State waters from adverse stormwater runoff impacts. The migration or release of silty water or mud from the applicant's property will be considered a violation of County and State water quality protection regulations. Please feel free to contact me at 724 if you have any questions regarding these comments, or if you feel any features need further discussion or attention. Sin ely, 1 John Sliva Programs Engineer MASON COUNTY PUBLIC WORKS WORK ORDER REG I Permit#: L Date: tlo Requested by: _ Au Authorized by: Type of Work: Public Works employee in charge: ,;,Jo K CHARGE TO: Name: Billing Address: Phone: WORK PERFORMED: Employee: l-huh t� Date: Hours: 1 Hourly Rate: y S Total: f , ACCOUNTS RECEIVABLE INFO: Billed Date: Invoice #: Amount Billed: Receipt# Date: Amount Paid: RECEIVED JUL 2 0 2006 MASONCOl11aTYPi MM STORMWATER AND EROSION/SEDIMENT CONTROL SITE PLAN for Equestrian Riding Arena Site Location: 4771 E SR 3, Shelton, Washington Prepared for Owner/Contractor: Michael N. O'Day Janis Snoey Hawk Hill LLC 4771 E SR 3 Shelton, WA 98584 Phone: (360) 426-8431 Cell: 360-791-3636 Prepared by: MARLEY L. YOUNG,CONSULTING ENGINEER P.O. Box 1343 Shelton,WA 98584 Phone: (360)426-7475/cell(360) 490-0939 Fax: (360)426-5789 e-mail: myoung3542@aol.com Project No. 2006-33 July 19,2006 l �. MARLEY L. YOUNG, CONSULTING ENGINEER :Civil Engineering] P.O. BOX 1343, SHELTON, WA 98584-0959 Stormwater site Plans (360)426-7475 FAX (360)426-5789 Sewer Extensions Marley L. Young, P.E., P.L.S. o Civil Engineer&Land Surveyor O IIIIIIIII PROJECT ENGINEER'S CERTIFICATION I hereby certify that this Stormwater and Erosion/Sediment Control Site Plan prepared for Michael N. O'Day,has been prepared by me or under my supervision and meets minimum standards of Mason County and normal standards of engineering practice. I understand that the jurisdiction does not and will not assume liability for the sufficiency, suitability,or performance of drainage facilities designed by me. Marley L. Young,P.E.,P.L.S. tSSQ¢o�Y 5d t1° . `FSA �C 14144 d IXri"n=� s/5/p$ Marley L.Young,Consulting Engineer Project No.2006-33 Son County Map Output Page Page rof 1 J u+s•r"o2 Mason County Map + 4 53 LEGEND ;11lp1 { y Hlgt-"Vr1's Cnv of Shelt;n ==ts+itttttt+ RlvcaeRFlrvurt'le: ;;ir,XdyFYi•up.,Ify F�re.ls Comni*w)r-piDstm;W acuaos � L�kaS gpN72 , t s 3 s:r DISCLAIMER AND LIMITATION OF LIABILITY: t The data used to make This map have been tested for accuracy,and every effort has been made to ensure that these data are timely,accurate and reliable.However, Mason County makes no guarantee or warranty to its accuracy as to labeling,dimensions,or placement or location of any map features contained herein.The boundaries depicted by these data are approximule,and are not necessarily accurate to surveying or engineering + standards,and are intended for informational purposes only.Mason County does not assume any legal liability or responsibility arising from the use of this map in it s4s manner not intended by Mason County.In no event shall Mason County be liable for direct,indirect,incidental, consequential.special.or tort damages of any kind, 347 including,but not limited to,loss of anticipated profits or benefits arising from use of or reliance on the information contained herein soou+ooeae oost i . � O 2006-Mason County GIS 415 N.Sixth Street Shelton,WA 98584 Michael O'Day—Equestrian Riding Arena TABLE OF CONTENTS Page Engineer's Certification Table of Contents Best Management Practices(BMPs) .............................................................. 1 Large Parcel Stormwater Site Plan I. Project Overview .............................................................. 2 Minimum Requirements#2411 .............................................................. 2 U. Plot Plan .............................................................. III. Preliminary Conditions Summary .............................................. W. Off-site Analysis ...................................... 4 V. Permanent Stormwater Quality Control Plan .......................... ............ ...... 4 Storm Event Design Assumptions .............................................................. 4 WaterWorks History 5-6F VI. Special Reports and Studies (Not Applicable to this Plan) ...................................... 7 VII. Basin and Community Planning(NA) .............................................................. 7 VIII. Permits .............................................................. IX. Erosion and Sediment Control Plan .............................................................. 7 Minimum Requirements#I-#15 .............................................................. 7 X. Bond Quantity Worksheets(NA),Detention Facility Summary Sheet and Sketch (NA), Declaration of Covenant .............................................................. 9 XI. Operation and Maintenance Manual .............................................................. 10 Changed Conditions .............................................................. 10 ATTACHMENTS SUPPORTING CALCULATIONS Marley L.Young,Consulting Engineer Project No.2006-33 l t STORMWATER AND EROSION/SEDIMENT CONTROL SITE PLAN for A 17,600 Square Foot Equestrian Riding Arena Located on Private Property Owned by Michael N. O'Day The Puget Sound Water Quality Management Plan(PSWQMP),which is administered by the State of Washington Department of Ecology,mandates that all counties and cities within the Puget Sound drainage basin adopt ordinances to control runoff from new development and redevelopments. The PSWQMP also directs local governments to adopt stormwater programs that must include minimum requirements that are consistent with the PSWQMP,and which are substantially equivalent to the Dept.of Ecology's Stormwater Management Manual for the Puget Sound Basin,(Ecology's Technical Manual). The goal of the Puget Sound Water Quality Management Plan is to: ■ Protect and restore beneficial uses of aquatic resources, including shellfish beds, fish habitat,and other resources; ■ Prevent contamination of sediments from urban runoff; ■ Meet standards for water and sediment quality by reducing pollutant discharges from stormwater throughout Puget Sound. BEST MANAGEMENT PRACTICES(BMPs) Best management practices(BMPs)are defined as physical, structural,or management practices that, when used singly or in combination,prevent or reduce pollution of water. Specific BMPs have been developed by Ecology to control stormwater runoff(quality and quantity)for protection of receiving waters. There are three main reasons for applying BMPs before considering advanced treatment. First, it has been shown through research and experience that BMPs can significantly reduce pollutants in stormwater. Using BMPs to control localized discharges is cost effective in comparison to treating large volumes of water. Second,our lakes and streams depend on stormwater to provide adequate flow for fish habitat and water quality. Our groundwater resources also depend on stormwater for recharge. BMP implementation offers a way to discharge water back into the natural system. Third,and perhaps most important,stormwater management programs demand the conscientious use of best management practices to protect water quality. Specific BMPs that cover stormwater runoff quality and quantity have been included in Ecology's Technical Manual. Those BMPs can be divided into three basic categories, including Source Control BMPs, Runoff Treatment BMPs and Streambank Erosion Control BMPs. Source Control BMPs are designed to prevent pollutants from entering stormwater by eliminating the source of pollution or by preventing contact of pollutants with rainfall and runoff. Source controls are usually the most cost-effective because they reduce or eliminate the need for treatment BMPs. Implementing source control BMPs generally involves relatively simple and straightforward actions. Examples of source control BMPs include erosion control(e.g.,covering disturbed soil),covering material storage areas,and eliminating illicit discharges. Marley L.Young,Consulting Engineer Project No.2006-33 Michael O'Day—Equestrian Riding Arena Runoff Treatment BMPs are designed to remove pollutants contained in stormwater runoff. These types of BMPs are the second line of defense in protecting stormwater quality. Examples of runoff treatment BMPs include infiltrated basins,bioswales and sediment ponds. Streambank Erosion Control BMPs are designed to protect stream ecosystems from erosion and sedimentation. Types of streambank erosion control BMPs include flow attenuation BMPs for reducing peak flows from a development(e.g.,detention ponds, infiltration trenches), and streamside stabilization BMPs used to stabilize eroding streambanks. I. PROJECT OVERVIEW PROPOSED PROJECT DESCRIPTION: Mr.O'Day is proposing to construct a roof-covered equestrian riding arena 80 feet wide by 200 feet long. Because the roof area is 17,600 SF,this proposal has caused Mason County to stipulate that a stormwater control plan must be prepared by a Civil Engineer and approved by the county. This report will focus on the amount of runoff that is collected by the riding arena roof and what should be done to reduce this runoff to a quantity that is less than the calculated undeveloped run off. The proposed location of the arena is just easterly of the existing horse barn. A forest exists easterly and southeasterly of the proposed arena,running beyond the O'Day property boundaries. O'Day's easterly property boundary lies approximately 800 feet from the arena,and the south boundary lies approximately 1,100 feet from the arena. Any runoff from the arena roof that is discharged into the forest will use the natural vegetation for treatment and infiltration. A shallow infiltration ditch will be constructed along three sides of the arena. The roof runoff that is not infiltrated while in the trenches will be directed to a final infiltration trench that is constructed with a level top. This last trench shall allow remaining runoff to fill the trench and spill uniformly out of the trench and sheet flow into the forest. The calculated runoff entering the trees will be less than the calculated undeveloped runoff and will also satisfy stream bank erosion control requirements. LEGAL DESCRIPTION The site is located in the SW '/4 of the SW '/a of Section 35,Township 21 North,Range 3 West,W.M., Mason County, Washington. Mason County Auditor's Parcel No. 321-35-3300000 EXISTING CONDITIONS: The forty-acre site contains an operating horse ranch and residence. GENERAL LOCATION: The site address is 4771 E SR3, Shelton,Washington 98584. STORMWATER AND EROSION/SEDIMENT CONTROL PLAN REOUIREMENT DETERMINATION: Projects that add 5,000 square feet or more of new impervious surface must comply with the Large Parcel Minimum Requirements. A Large Parcel Erosion and Sediment Control Plan is discussed,and the necessary BMPs are included in this report. The report will review the components of the Large Parcel Stormwater Site Plan,which include the temporary erosion and sediment control necessary during construction,permanent stormwater 2 Marley L.Young,Consulting Engineer Project No.2006-33 a Michael O'Day—Equestrian Riding Arena quantity control,civil drawings and specifications,and operation and maintenance recommendations for the needed stormwater facilities. This project will comply with the following Large Parcel minimum Requirements#2 through#11 found in Section I-2.5 through I-2.15 of the Department of Ecology's Stormwater Management Manual for the Puget Sound Basin(the Technical manual). Minimum Requirement#2: PRESERVATION OF NATURAL DRAINAGE SYSTEMS Natural drainage patterns shall be maintained,and discharges from the site shall occur at the natural location,to the maximum extent practicable. No surface water drainage flows through this project. The stormwater control solution will complement the forested areas and the contours. Minimum Requirement#3: SOURCE CONTROL OF POLLUTION Soil erosion and gravel migration are not expected to become an issue. Soils are classified asAlderwood (Ab), SCS Soil Group C. If deemed necessary to prevent the migration of silt during construction, the owner/contractor shall construct channels to keep overland flows away from the area under construction. If dust becomes a problem, dust control methods using water shall be employed. If required, migrat ion-sensitive soils shall be covered with straw mulch or black plastic to prevent off-site migration of soil. This project is located far from any stream and is 2,000 feet plus away from any public highway. An existing forest lies to the south and down slope from the arena and will act as a buffer to minimize the impact of the arena runoff. The erosion control plan shall be simple. Install hay bales when deemed necessary because of any signs of erosion. Hay bales are chosen because on a horse ranch they are readily available. Minimum Requirement#4: RUNOFF TREATMENT BMPS The final discharge into the forest will act as treatment. Minimum Requirement#5: STREAMBANK EROSION CONTROL argued be ar it might meeting Although ht ed that Streambank Erosion Control is not required, the sheet flow into g g the woods will meet and exceed Streambank Erosion Control. Minimum Requirement#6: WETLANDS NA—Thesi te does not include wetlands. Minimum Requirement#7: WATER QUALITY SENSITIVE AREAS NA Minimum Requirement#8: OFF-SITE ANALYSIS AND MITIGATION NA—The calculated final runoff is less than the calculatedpre project runoff; therefore, offsite analysis is not required. Minimum Requirement#9: BASIN PLANNING An adopted and implemented basin plan may be used to develop requirements for water quality sensitive areas that are tailored to a specific basin. NA—No basin plan has been established at this location. 3 Marley L.Young,Consulting Engineer Project No.2006-33 Michael O'Day—Equestrian Riding Arena Minimum Requirement#10: OPERATION AND MAINTENANCE An operation and maintenance schedule shall be required for all proposed stormwater facilities and BMPs, and the party(or parties)responsible for maintenance shall be identified. The owner is responsible for operation and maintenance of the stormwater facilities. To ensure that the �\ proposed stormwater control facilities are adequately operated and maintained, an Operation and Maintenance (O&* Covenant will be required. A "Declaration of Covenants Associated With rivately Maintained Storm Drainage Facilities"has been created for the proposed stormwater facilities. he applicant will need to complete the form, record the signed and notarized document with the C PP County Auditor's office, and deliver a copy of the recorded document to Mason County Public Works for monitoring and administration. A copy of the unsigned document is included in the Attachments. Minimum Requirement#11: FINANCIAL LIABILITY Performance bonding or other appropriate financial instruments shall be required for all projects to ensure compliance with these standards. NA—Mason County has not indicated that a financial instrument will be required. II. PLOT PLAN Engineer's Civil Drawings have been developed for the project showing the location of the improvements and the layout of the proposed Permanent Stormwater Control BMPs, and an Erosion/Sediment Control Plan to be used during construction. By reference these drawings are made a part of this report. III. PRELIMINARY CONDITIONS SUMMARY See Section I, Project Overview. IV. OFF-SITE ANALYSIS (No off-site analysis is required. See Min. Req. #8 above.) Wetlands or Water of the State This site does not contain wetlands. Analysis of the 100-year Flood This site does not contain or abut a Federal Emergency Management Administration(FEMA)identified stream and is,therefore,outside any 100-year flood plain. V. PERMANENT STORMWATER QUALITY CONTROL PLAN All storm events are collected and directed to the infiltration trench through a grass swale STORM EVENT DESIGN ASSUMPTIONS Based on DOE's Stormwater Management Manual: STORM EVENT The stormwater program Water Works(software for hydrology by Engenious Systems, Inc.)was used to model the storm flows,retention, infiltration and releases. Rain Precipitation(in.) Six-month,24-hour Storm Event 2.40 (6-mo. @ 64% of 2-yr.) Two-year,24-hour Storm Event 3.75 Ten-year, 24-hours Storm Event 5.20 Hundred-year, 24-hour Storm Event 7.25 4 Marley L.Young,Consulting Engineer Project No.2006-33 i Michael O'Day—Equestrian Riding Arena Rainfall choice IA Hydrograph SBUH** ** Santa Barbara Urban Hydrograph method DRAINAGE BASIN Alderwood gravelly sandy loam(Ab), 5-15 percent slopes Hydrologic Soil Group C Infiltration Rate for Trench 20&30 min./inch CN#for Post Development Impervious-Roof 98 CN#for Pre Development Pervious 85 Grass 87 NOTE: Given the Storm Event, Soil Type and Land Use,the Runoff Curve Number(CN#) is an indicator of the total surface and subsurface runoff. ACREAGE UNDER CONSIDERATION Equestrian Riding Arena—220'x80' = 17,600 sf=0.40 acres One quarter of roof area plus=0.14 acres One half of roof area plus=0.28 acres Total roof area plus=0.56 acres Grassy area=0.28 acres Pre developed area under consideration=0.83 acres STORMWATER CALCULATIONS The following is the"History"printout from WaterWorks. The History shows the calculated reduction of cfs caused by infiltration and the final discharge to the woods. It also compares the final discharge to the pre project discharge. For ease of reading the history,the explanation of abbreviations and codes is included: BASIN ID: are defined as: ra=The calculated runoff for'/4 of the arena and roof area for a 6-month,24-hour storm event. rb=The calculated runoff for%4 of the arena and roof area for a 2-year,24-hour storm event. rc=The calculated runoff for'/4 of the arena and roof area for a 10-year,24-hour storm event. rd=The calculated runoff for'/4 of the arena and roof area for a 100-year,24-hour storm event. The ra through rd is used twice to represent the north half of the roof. Because WaterWorks does not have a method of calculating a rock filled trench for runoff and infiltration,the engineer must narrow the trench width to compensate for the lost volume caused by the washed rock. For calculation purposes the width of Troofl,Troof2,Troof3,and Troof4 is reduced by 3 3%to 1.16 feet. Note: The construction width of each trench shall be 3.5 feet. Troofl is the first infiltration trench and follows the northerly long side of the arena. 2ra=The calculated runoff for'/2 of the arena roof area to flow to the trench on the southerly side of the arena for a 6-month,24-hour storm event. 2rb=The calculated runoff for'/z of the arena roof area to flow to the trench on the southerly side of the arena for a 2-year,24-hour storm event. 2rc=The calculated runoff for'/z of the arena roof area to flow to the trench on the southerly side of the arena for a 10-year,24-hour storm event. 2rd=The calculated runoff for'/z of the arena roof area to flow to the trench on the southerly side of the 5 Marley L.Young,Consulting Engineer Project No.2006-33 Marley Young Engineer page 1 7/13/06 8:29:45 pm MICHAEL O'DAY 4771 E SR3 Horse Arena Stormwater Control Proj 2006-33 HISTORY OF HYDROGRAPH ACTIVITY Date of Session: 7/13/06 8:29:36 pm CLEARRIS REMARK ra thru rd are the 6 month, 2 year, 10 year and 100 year storm events over 1/2 of the roof area. Dividing the roof into two parts was down to determine the smallest diam. drain pipe. LSTEND MOVE ra to 1 0.0688 cfs 0.0253 ac-ft 8.00 hrs MOVE rb to 2 D.1095 cfs 0.0409 ac-ft 8.00 hrs MOVE rc to 3 0.1528 cfs 0.0578 ac-ft 8.00 hrs MOVE rd to 4 0.2138 cfs 0.0817 ac-ft 8.00 hrs REMARK Troofl is the rock filled trench running below the north roof line. Troofl is 110' long (half the roof length). Troofl provides some infiltration. The four PkStg and OutQ represent the four storm events. LSTEND LPOOL 1 16M0" 1 1 Troofl W 5 ume Description Match0Q PeeakOQ StTZoofDisW Pk49g31 OUt03 hyd Vo1167.41 cf bM0 LPOOL 2 "2YR" 2 2 Troofl W 6 Description MatchQ PeakQ Sto Dis PkStq OutQ hyd Volume 2YR 0.11 0.11 Troofl W 100.06 0.11 6 263.03 cf LPOOL 3 110YR" 3 3 Troofl W 7 OutQ hyd Volume Description MatchQ PeakQ Sto Dis PkStq 10YR 0.15 0.15 Troofl W 100.03 0.15 7 259.52 cf LPOOL 4 "100YR" 4 4 Troofl W 8 Description MatchQ 0. 1 Troofl W PeakQ STrDis P100g05 OutQ hyd hyd8 Vo12me 61.85 cf 100YR REMARK The four SPLIT below again represent the four storm events. The top # cfs flows above ground and the second # infiltrates to ground. LSTEND SPLIT W 1 13 17 0.0000 cfs 0.0000 ac-ft 0.00 hrs 0.0291 cfs 0.0253 ac-ft 8.67 hrs SPLIT W 2 14 18 0.1095 cfs 0.0022 ac-ft 8.08 hrs 0.0399 cfs 0.0387 ac-ft 8.25 hrs Co A MICHAEL O'DAY 4771 E SR3 Horse Arena Stormwater Control Proj 2006-33 ------------------------------------------------------------------ ---------------------------------- HISTORY OF HYDROGRAPH ACTIVITY SPLIT W 3 15 19 0.1124 cfs 0.0072 ac-ft 8.08 brs 0.0403 cfs 0.0502 ac-ft 8.08 brs SPLIT W 4 16 20 0.1730 cfs 0.0184 ac-ft 8.08 hrs 0.0405 cfs 0.0620 ac-ft 8.08 hrs REMARK Below the storm discharge from the second half to the north side of the arena is is added to the above ground flow shown earlier. LSTEND ADD 1 13 9 0.0688 cfs 0.0253 ac-ft 8.00 hrs ADD 2 14 10 0.1982 cfs 0.0432 ac-ft 8.08 hrs ADD 3 15 11 0.2648 cfs 0.0650 ac-ft 8.00 hrs ADD 4 16 12 0.3867 cfs 0.1001 ac-ft 8.00 hrs ZERO 1 8 REMARK Troof2 is the rock filled trench that located below the remaining northerly roof eave and continues along the east end of the arena to the south east corner of the arena. Troof2 is 190' long and provides some infiltation. LSTBND LPOOL 1 06M0" 9 9 Troof2 W 5 Description MatchQ PeakQ Sto Dis PkStq OutQ hyd Volume 6MO 0.07 0.07 Troof2 W 98.85 0.03 5 188.42 cf LPOOL 2 "2YR" 10 10 Troof2 W 6 Description MatchQ PeakQ Sto Dis PkStg OutQ hyd Volume 2YR 0.20 0.20 Troof2 W 99.99 0.05 6 438.74 cf LPOOL 3 "IOYR" 11 11 Troof2 W 7 Description MatchQ PeakQ Sto Dis PkStg OutQ hyd Volume 10YR 0.26 0.26 Troof2 W 100.08 0.26 7 459.14 cf LPOOL 4 0100YR° 12 12 Troof2 W 8 Description MatchQ PeakQ Sto Dis PkStg OutQ hyd Volume 100YR 0.39 0.39 Troof2 W 100.10 0.39 8 463.05 cf REMARK In the SPLIT the top # cfs will flow southwesterly and the bottom # will infiltate. Note that the 6 month storm event has infiltated to ground and none is available to discharge further down the pipe. LSTBND (o 13 page MICHAEL O'DAY 4771 E SR3 Horse Arena Stormwater Control Proj 2006-33 HISTORY OF HYDROGRAPH ACTIVITY SPLIT W 1 13 17 0.0000 cfs 0.0000 ac-ft 0.00 hrs 0.0253 cfs 0.0252 ac-ft 9.08 hrs SPLIT W 2 14 18 0.0000 cfs 0.0000 ac-ft 0.00 hrs 0.0454 cfs 0.0430 ac-ft 8.92 hrs SPLIT W 3 15 19 0.2648 cfs 0.0114 ac-ft 7.92 hrs 0.0168 cfs 0.0527 ac-ft 8.17 hrs SPLIT W 4 16 20 0.3386 cfs 0.0312 ac-ft 8.08 hrs 0.0474 cfs 0.0664 ac-ft 8.08 hrs REMARK the total south half of the roof area (220 x 40) is shown as 2ra thru 2rd, (the four store events). These discharges are colled in the trench below the arena south eave. LSTEN➢ MOVE 2ra to 1 0.1377 cfs 0.0506 ac-ft 8.00 hrs MOVE 2rb to 2 0.2189 cfs 0.0819 ac-ft 8.00 hrs MOVE 2rc to 3 0.3055 cfs 0.1156 ac-ft 8.00 hrs MOVE 2rd to 4, 0.4276 cfs 0.1633 ac-ft 8.00 hrs RENARE Troof3 is the rock filled trench that located below the southerly roof eave and will connect with Troof2 at the south east corner of the arena. Troof3 is 2201 long and provides some infiltation. LSTEND LPOOL 1 5690" 1 1 Troof3 W 5 Description MatchQ PeakQ Sto Dis PkStg OutQ hyd Volume 6M0 0.14 0.14 Troof3 W 99.79 0.05 5 456.57 cf LPOOL 2 °2YR° 2 2 Troof3 W 6 Description MatchQ PeakQ Sto Dis PkStg OutQ hyd Volume 2YR 0.22 0.22 Troof3 W 100.08 0.22 6 529.64 cf LPOOL 3 'IOYR° 3 3 Troof3 W 7 Description MatchQ PeakQ Sto Dis PkStg OutQ hyd Volume 10YR 0.31 0.31 Troof3 W 100.08 0.31 7 529.69 cf LPOOL 4 0100YRO 4 4 Troof3 W 8 Description MatchQ PeakQ Sto ➢is PkStg OutQ hyd Volume / MICHAEL O'DAYr r 4771 E SR3 Horse Arena Stormwater Control Proj 2006-33 HISTORY OF HYDROGRAPH ACTIVITY 100YR 0.43 0.43 Troof3 W 100.13 0.43 8 544.81 cf RENARK In the SPLIT below the top # cfs will flow southwesterly and the bottom # will infiltate. LSTEND SPLIT W 1 9 17 0.0000 cfs 0.0000 ac-ft 0.00 hrs 0.0485 cfs 0.0502 ac-ft 9.17 hrs SPLIT W 2 10 18 0.2189 cfs 0.0118 ac-ft 7.83 hrs 0.0534 cfs 0.0681 ac-ft 8.25 hrs SPLIT W 3 11 19 0.2510 cfs 0.0271 ac-ft 8.08 hrs 0.0543 cfs 0.0842 ac-ft 8.08 hrs SPLIT W 4 12 20 0.4276 cfs 0.0616 ac-ft 8.00 hrs 0.0549 cfs 0.0949 ac-ft 7.92 hrs ZERO 17 20 RENARK The ADD below is combining the total runoff from the roof arena that has not been infiltrated. These flows are directed south westerly in another trench. LSTEND ADD 9 13 17 0.0000 cfs 0.0000 ac-ft 0.00 hrs ADD 10 14 18 0.2189 cfs 0.0118 ac-ft 7.83 hrs ADD 11 15 19 0.5158 cfs 0.0384 ac-ft 8.08 hrs ADD 12 16 20 0.7662 cfs 0.0928 ac-ft 8.08 hrs REMARK Troof4 is the rock filled trench that located along the grass slope and connects with Troof2 and Troof3 at the south east corner of the arena. Troof4 is 200' long and provides some infiltation. LSTEND LPOOL 1 "00" 17 17 Troof4 W 5 Description NatchQ PeakQ Sto Dis PkStg OutQ hyd Volume 6NO 0.00 0.00 Troof4 W 98.00 0.00 5 0.00 cf LPOOL 2 "ZYR" 18 18 TIoof4 W 6 Description NatchQ PeakQ Sto Dis PkStg OatQ hyd Volume 2YR 0.22 0.22 Troof4 W 99.30 0.05 6 301.79 cf (Q D MICHAEL O'DAY 4771 E SR3 Horse Arena Stormwater Control Proj 2006-33 ------- HISTORY OF HYDROGRAPH ACTIVITY LPOOL 3 '10YR' 19 19 Troof4 W 7 Description MatchQ PeakQ Sto Dis PkStg OutQ hpd Volume IOYR 0.52 0.52 Troof4 W 100.14 0.52 7 496.88 cf LPOOL 4 5100YR' 20 20 Troof4 W 8 Description MatchQ PeakQ Sto Dis PkStg OutQ hpd Volume 100YR 0.77 0.77 Troof4 W 100.17 0.77 8 502.77 cf REMARK In the SPLIT the top # cfs will flow southerly into the trees and the bottom # will infiltate. Note that the 6 month story event has infiltated to ground and none is available to discharge further down the pipe. LSTEND SPLIT W 1 9 13 0.0000 cfs 0.0000 ac-ft 0.00 hrs 0.0000 cfs 0.0000 ac-ft 0.00 hrs SPLIT W 2 10 14 0.0000 cfs 0.0000 ac-ft 0.00 hrs 0.0525 cfs 0.0118 ac-ft 8.42 hrs SPLIT W 3 11 15 0.5158 cfs 0.0125 ac-ft 8.17 hrs 0.0751 cfs 0.0255 ac-ft 8.25 hrs SPLIT W 4 12 16 0.7662 cfs 0.0456 ac-ft 8.17 hrs 0.0762 cfs 0.0472 ac-ft 8.08 hrs REMARK The da thru dd is the four storm events on the area of the grass slope between the grass slope and the arena. This area is expected to sheet flow into the trees. LSTEND MOVE da to 1 0.0758 cfs 0.0286 ac-ft 8.00 hrs MOVE db to 2 0.1563 cfs 0.0561 ac-ft 8.00 hrs MOVE do to 3 0.2464 cfs 0.0875 ac-ft 8.00 hrs MOVE dd to 4 0.3747 cfs 0.1332 ac-ft 8.00 hrs REMARK Below the final roof runoff and the grass slope runoff are combined for a total. Note - all the pipes are to be perforated, and the last trench (Troof4) is expected to fill to capacity and sheet flow to the trees. The trench should be as level as practical. 7/13/06 8.29:45 pm Mariey Young nngiaeer rayC MICHAEL O`DAY 4771 E SR3 Horse Arena Stormwater Control Proj 2006-33 HISTORY OF HYDROGRAPH ACTIVITY These four ADD 1 cfs thru ADD 4 cfs represent the four storm events and must be compared to A thru D below. LSTEND ADD 1 9 13 0.0758 cfs 0.0286 ac-ft 8.00 hrs ADD 2 10 14 0.1563 cfs 0.0561 ac-ft 8.00 hrs ADD 3 11 15 0.6552 cfs 0.0999 ac-ft 8.17 hrs ADD 4 12 16 0.9998 cfs 0.1789 ac-ft 8.00 hrs REMARK A thru D are the calculated Pre developed runoff. As per the 'manual' the Post- runoff roust not exceed the Pre developed runoff. Note- no strean are in the area, however the Stream Bank Erosion Control requirement is satisfied. LSTEND MOVE A to 1 0.1814 cfs 0.0755 ac-ft 8.00 hrs MOVE B to 2 0.4022 cfs 0.1535 ac-ft 8.00 hrs MOVE C to 3 0.6569 cfs 0.2440 ac-ft 8.00 hrs MOVE D to 4 1.0246 cfs 0.3772 ac-ft 8.00 hrs REMARK NOTE - A thru D cfs are greater than the four ADD immediately above. O.H. LSTEND End program file E:\EGENIO-1\06-330DA.pgE � r Michael O'Day—Equestrian Riding Arena VI. SPECIAL REPORTS AND STUDIES None VII. BASIN AND COMMUNITY PLANNING NA VIIL PERMITS Agency Permit/Approval Mason County Building Permit IX. EROSION and SEDIMENT CONTROL PLAN Temporary Erosion Control This project includes temporary erosion control. See Civil Drawings. The disturbance to the property is minimal. The types of soils are sandy,gravelly, and do not lend themselves to migration. Erosion control will use hay/straw bales. Because of the gravelly texture of the soil, silt and soil migration is not considered to become a problem. Project Description/Existing Site Conditions Refer to Section I, Project Overview. Adjacent Areas Impacts NA—No impact anticipated. SCS Soils Description The Soil conservation Service—Soil Survey of Mason County Series 1951,No.9,Issued September 1969, shows this property having soils type Alderwood gravelly sandy loam(Ab), 5-15 percent slopes. Soils conditions found on the property may not match exactly the soils described by SCS. Critical Areas No critical areas have been identified on this site. Erosion and Sediment Control Measures Minimum Requirements Mason County has adopted the Department of Ecology"Stormwater Management Manual for the Puget Sound Basin. All projects that disturb more than one acre must develop a Permanent Stormwater Quality Control Plan. (Mason County Ordinance 141-97) EROSION AND SEDIMENT CONTROL REQUIREMENTS I feel that the erosion and sediment control system hereinafter proposed will adequately provide the necessary erosion and sediment protection. The fifteen large parcel minimum requirements specified by DOE are: #1: Stabilization and Sediment Trapping All exposed and unworked soils shall be stabilized by suitable application of BMPs. From October I to April 30,no exposed and unworked soils shall remain unstabilized for more than 2 days. From May 1 to September 30,no exposed and unworked soils shall remain unstabilized for more than 7 days. Prior to 7 Marley L.Young,Consulting Engineer Project No.2006-33 Michael O'Day—Equestrian Riding Arena leaving the site, stormwater runoff shall pass through a sediment pond or sediment trap,or other appropriate BMPs. #2: Delineate Clearing and Easement Limits The clearing limits shall be defined by the owner. #3: Protection of Adjacent Properties The underlying soils have very little potential for migration. Protecting adjacent property from damage from sediment deposition does not appear to be a problem. #4: Timing and Stabilization of Sediment Trapping Measures Sediment traps will be used as necessary. #5: Cut and Fill Slopes Other than the construction of the shallow vertical-sided infiltration trench, no other slopes are proposed. #6: Controlling Off-site Erosion Off-site erosion is not anticipated to become an issue. #7: Stabilization of Temporary Conveyance Channels and Outlets The water velocity for ground surface flows is not anticipated to reach erosion velocity. All stormwater will be infiltrated on site. #8: Storm Drain Inlet Protection N/A—No storm drain inlets in the area. #9: Underground Utility Construction Architectural and Civil drawings put contractor on notice as to the installation requirements of underground utilities. #10: Construction Access Routes Construction vehicles access shall be,whenever possible,limited to one route. Access points shall be stabilized to minimize the tracking of sediment onto public roads. There is one access to the site for construction purposes. Note: The project is approximately 2,000 feet away from SR3. #11: Removal of Temporary BMPs All temporary erosion and sediment control BMPs will be removed when final site stabilization is achieved. #12: Dewatering Construction Sites N/A #13: Control of Pollutants Other Than Sediment on Construction Sites All pollutants other than sediments that occur onsite during construction shall be handled and disposed of in a manner that does not cause contamination of stormwater. #14: Maintenance All temporary and permanent erosion and sediment control BMPs shall be maintained and repaired as needed to assure continued performance of their intended function. 8 Marley L.Young,Consulting Engineer Project No.2006-33 t Michael O'Day—Equestrian Riding Arena #15: Financial Liability Not Applicable to this project. Permanent Stabilization At the conclusion of site construction improvements,within seven days Wrmanent site stabilization shall be completed by spreading seed and mulch on all exposed soils to establish a ground cover. Use the following recommended seed mixture for erosion control or a County-approved alternate seed mixture. Proportions Percent Percent Name by Wei t Purity Germination Redtop(Aerostis alba) 10 percent 92 90 Annual rye(Lolium multiflorum) 40 percent 98 90 Chewing fescue 40 percent 97 80 (Festuca rubra commutata) (Jamestown.Banner,Shodow,or Koket) White dutch clover(Trifolium repens) 10 percent 96 90 The following is a guide for use of recommended mulch material: Application Rates Depth Mulch Quality Per 1000 Per of Material Standards Sg.Feet Acre Application Remarks Gravel,Crushed Washed 3/.to 9 CY 3 inches Good for short slope and Stone 1'/z-inch around woody plants and ornaments. Use where Subject to foot traffic. Hay or straw Air dry.Free from 75-100 lbs 1.5 to Min.2 inches Use where needed for more weed seed and pounds 2.5 tons than 3 mos. Subject to coarse material. (Approx. blowing--keep moist or 2 in.thick) 90-120 Bales When used on critical areas, Wood Fiber No growth organism 25 to 30 1000 to 1500 double application rate. Cellulose(Partly inhibiting factors pounds pounds Apply with hydromulcher. Digested wood factors. No tie-down required. fibers) Stormwater Management Considerations Please see Section V, "Permanent Stormwater Quality Control Plan"for a complete description of the Sormwater management plan. Maintenance The responsibility for maintaining the facilities will lie with the owners of the property or their assigns. For maintenance recommendations please see Section XI, "Operation and Maintenance Manual"below. Calculations Calculations are briefly described in Section V, "Permanent Stormwater Quality Control Plan"above, and included in the attached Supporting Calculations. X. BOND QUANTITIES WORKSHEET,RETENTIONMETENTION FACILITY SUMMARY SHEET AND SKETCH,AND DECLARATION OF COVENANT Bond Quantities Worksheet—NA Retention/Detention Facility Summary sheet—NA 9 Marley L.Young,Consulting Engineer Project No.2006-33 1 Michael O'Day—Equestrian Riding Arena Declaration of Covenant—To ensure that the proposed stormwater control facilities are adequately operated and maintained,a "Declaration of Covenants Associated with Privately Maintained Storm Drainage Facilities"will be required to be created for the proposed stormwater facilities. The applicant will need to complete the form,record the signed and notarized document with the County Auditor's office, and deliver a copy of the recorded document to Public Works for monitoring and administration. A!gQa ofthe unsigned document is included in the Attachments. XI. OPERATION&MAINTENANCE MANUAL MAINTENANCE PLAN The responsibility for maintaining the facilities will lie with the owners of the property or their assigns (e.g.,Contractor). The facilities are designed to minimize the need for extensive maintenance. MAINTENANCE OF TEMPORARY EROSION BMWs DURING CONSTRUCTION During construction the major maintenance activity is to inspect the hay/straw bales. If the drainage carries mud or debris,hay/straw bales should be placed in the path of the drainage to eliminate any siltation from exiting the project site. All erosion and sediment control BMPs installed shall be inspected regularly,especially after any rm. Maintenance including removal and proper disposal of sediment should be done as large storm. g P Pe . necessary. (Generally sediment that restricts the sheet flow or infiltration must be removed.) MAINTENANCE OF PERMANENT STORMWATER CONTROL FACILITIES The final trench should be inspected to ensure that stormwater that escapes the trench sheet flows uniformly along its length and does not cause sediment migration or erosion before or after entering the trees. CHANGED CONDITIONS: The conclusions and recommendations in this report are based on my interpretation of site conditions,and the expectation that my onsite exploratory efforts adequately define the surface and sub-surface conditions throughout the site. In the event that the scope of the project or location of the improvements or surface/subsurface conditions differ from those I relied on in this report,I should be advised. At that time,a review of the changed conditions will be made and alternative or remedial recommendations given as requested. This Stormwater Site Plan has been prepared by: 72� Marley L.You ,P. . 10 Marley L.Young,Consulting Engineyr Project No.2006-33 Michael O'Day-Equestrian Riding Arena ATTACHMENTS Marley L.Young,Consulting Engineer Project No.2006-33 Michael O'Day-Equestrian Riding Arena DECLARATION OF COVENANTS ASSOCIATED WITH PRIVATELY MAINTAINED STORM DRAINAGE FACILITIES (Copy of unsigned document) Marley L.Young,Consulting Engineer Project No.2006-33 RETURN ADDRESS GRANTOR(S)(Last,First and Middle Initials) GRANTEE: MASON COUNTY DEPARTMENT OF PUBLIC WORKS DECLARATION OF COVENANTS ASSOCIATED WITH PRIVATELY MAINTAINED STORM DRAINAGE FACILITIES Declaration of Covenant In consideration of approval of the development known as the Lilliwaup,Washington Post Office,relating to real property legally described as follows: SW'/<of the SW'/.Tract 2 of Survey 18/9,of Section 35,T21N,R3W,W.M.,Mason County WA County Assessor's Property Tax Parcel Number(s)32330-51-56013 The undersigned,as owner(s),covenant and agree that: 1. If at any time Mason County reasonably determines that maintenance or repair work is required to be done to the existing, approved storm drainage facilities installed on the property described above and located outside of any public right-of-way(which will mean repair and or clean out of the existing system only to the same standards as originally installed and approved), the Director of the Department of Public Works shall give the current owners seven days notice that the County intends to perform such maintenance or repairs, or to have them performed by others. If the current owners have not completed or are not diligently pursuing the repair or maintenance of the system and it becomes necessary for Mason County to perform the work, the current owners will assume responsibility for the cost of such maintenance or repair and will reimburse the County within thirty days of receipt of the invoice. Overdue payments will require payment of interest at the current legal rte for liquidated judgments, and any costs or fees incurred by the County, should any legal action be required to collect such payments,will be borne by the parties responsible for said reimbursements. 2. If at any time Mason County reasonably determines that the existing and approved storm drainage system on the property poses a hazard to life and limb, or endangers property, or adversely affects the safety and r non-maintenance of the existing on-site storms stem, to failure damage o o g Y operations of a public way, due g P P and that the situation is so adverse as to preclude written notice to said owners the Director of the Department of Public Works may take the measures necessary to eliminate the hazardous situation(which will mean repair or clean out of the existing system only to the same standards as originally installed and approved) provided the Director has first made a reasonable effort to locate said owner before acting. The current owners will assume responsibility for the cost of such maintenance or repair; and will reimburse the County within thirty days of receipt of the invoice. Overdue payments will require payment of interest at the current legal rate for liquidated judgments, and any costs or fees incurred by the County, should any be borne by the parties responsible for said reimbursements. 3. The owner shall keep the Mason County public Works Department informed at all times as to the name, address and telephone number of the contact person responsible for the performance of maintenance or repair work to the storm drainage facilities. These covenants are intended to protect the value and desirability of the real property described above, and to benefit all the citizens of Mason County. They shall run with the land and be binding on all parties having or acquiring from the current owners or their successors, any right, title or interest therein, and to the benefit of all the citizens of Mason County. Signature Signature Owner Owner City,State,Zip City,State,Zip Phone: Phone: STATE OF WASHINGTON, ss. (INDIVIDUAL ACKNOWLEDGMENT) County of MASON I, Notary Public in and for the State of Washington, residing at do hereby certify that on this _ day of , 20_, personally appeared before me to me know to be the individual described in and who executed the within instrument and acknowledged that signed and sealed the same as _ free and voluntary act and deed for the uses and purposes herein mentioned. GIVEN UNDER MY HAND AND OFFICIAL SEAL this_day of ,20_. Notary Public in and for the State of Washington,residing at in said County. My Commission expires ** Burn Ban in Effect ** Click I lore for more informaiton Mason County Fair-July 28th- 30th,2006- C'lick here fo more information Assessor i'�af cel aju13f13e1-: 32I35330011'10 w aP -n-CaSUrer Owner Information -- - 4771 E STATE ROUTE 3 c's iO'DAY,MICHAEL N&JANIS SNOEY �SHELTON WA 98584-8529 ►New Search -- - ►Parcel Detail Taxpayer Information __ - �(4771 E STATE ROUTE 3 ►Parcel Value O'DAY, MICHAEL N&JANIS SNOEY SHELTON WA 98584-8529 ►Site Built BIIlIC1111L5 Lego Description ►MH and Personal __ Property - ------- — - -- ISW SW TR 2 OF SURVEY 18/9 — -_ - -_ ►Sales Into Site Address 4771 E STATE ROUTE 3 SHELTON (1 Field Sheet FS 08983: ►Permits Reval Area , _ —' Land Use AGRICUL ►ProI1Ie (Summary Land Size* 40.00 (CURREN View of all items) - Tax Code 191 Tax Code Description 1 402 S P3 Census Tract Click Here * if the value is .00(zero)then the property is most likely in a plat and acreage is i carried on platted lots Last Updated:7/05/2006 Information may be inaccurate and outdated. Please refer to the Assessor/Treasurer Offices to verify any information assessor Home Treasurer Home search OIn bite Disclaimer )irector\ http://www.co.mason.wa.us/astr2/parcel detail.php?pucel_number=321353300000&Item... 7/18/2006 Ison County Map Output Page Page 1 bf 1 x ; ,3.7 Mason County Map a21347s951 LEGEND teas (ed0rai 1 arils 13a320000 .., 321M1 - 321347500154 �11gtkv0 C0V GP$haltecn P'V&S4Streams IJ Coonty rtiir;(mgp) . 4Sie1tCRI5 � Comml;s�brw,5'tk,tnrt5 __1 SlCttvn5 � tJIc4S ;. t�.I Townshys Pugat Sound S Majol L*V; As � s 3213475901 low 147SO0172 DISCLAIMER AND LIMITATION OF LIABILITY: uta}75utn The data used to make this map have been tested for accuracy,and every effort has been made to ensure that t these data are timely,accurate and reliable.However, Mason County makes no guarantee or warranty to its 321347s5N accuracy as to labeling,dimensions,or placement or location of any map features contained herein.The boundaries depicted by these data are approximate,and are not necessarily accurate to surveying or engineering t3g555t51 •• standards.and are intended for informational purposes t only.Mason County does not assume any legal liability Q or responsibility arising from the use of this map in a 32047550103 y manner not intended by Mason County.In no event shalt Macon County be liable for direct,indirect,incidental, consequential,special,or tort damages of any kind, ttl476N200 including,but not limited to,lass of anticipated profits or benefits arising from use of or reliance on the information contained herein 12M7/1 115001 � it 320922200039 ®2006-Mason County GIS 415 N.Sixth Street Shelton,WA 985M GEOTECKNICAL TESTING LABORATORY MICHAEL O'DAY JULY 7,2006 4771 EAST STATE ROUTE 3 SHELTON,WASHINGTON 98584-8529 RE: INFILTRATION TESTING PROJECT: 4771 EAST STATE ROUTE 3 SHELTON WASHINGTON 98584-8529 GPS LOCATION: N47015' 40.1" W1230 2' 6.7" PARCEL NUMBER: 321353300000 Gentlemen: As requested, infiltration testing has been conducted at the above referenced property. Six locations were selected for testing by Mr. Marley Young, the client's engineer. The plan for development at the site is an 80-foot by 220-foot horse riding arena. This structure will create an impervious area of 17,600 square feet, or approximately 0.4 acres. INFILTRATION TESTING The infiltration testing was repeated over four intervals. The last three intervals are used, eliminating the wetting front. The distance the water elevation fell was measured over a fixed time. Soils were tested at depths of 2-feet,3-feet, and 5-feet. The observed rate of infiltration ranged from 3.75 to 10 inches per hour. Using a factor of safety of 2, the reported rates of infiltration range from approximately Observed Rate [Factor lculated Rate with g LocationDe .� of Safety of 2 2 inches per hour to 5 Identification p (Inches/Hour) inches per hour. The Soil (Inches/Hour) Survey of Mason County, Washington, describes the #1 5 feet 3.75 1.875 infiltration of this soil as "Good". The Soil Survey #2 5 feet 4.375 2.1875 of Thurston County assigns the range of the Alderwood #3 2 Feet 3.75 1.875 gravelly sandy loam in the range of 2.0 to 6.0 inches per hour and this rate is #4 2 Feet 10 5 consistent with the observed rates in the field. #5 3 Feet 5.9375 2.96875 Testing locations are indicated on the site drawing(Last Page) #6 3 Feet 6.875 3.4375 10011 Blomberg Street SW,Olympia,WA 98512 1 Phone#(360)754-4612 Fax#(360)754-4848 GEOTECHNICAL TESTING LABORATORY REGIONAL GEOLOGY The Geologic Map of Washington — Northwest Quadrant (2002) has mapped the site geology as glacial outwash deposits(Qgo) of continental glacial origin. The report reads: Undifferentiated outwash —Recessional and proglacial stratified sand, gravel, and cobbles with minor silt and clay interbeds deposited in delta, ice-contact, beach, and meltwater stream environments; may include advance outwash. Includes part of the Partridge Gravel, ri undivided. part of the Everson Glaczomarrne Drift, and part of the Vashon D ft SITE GEOLOGY The Soil Survey of Mason County, Washington, USDA Soil Conservation Service (1960) has mapped the site soils in the northern portion of the parcel as Alderwood gravelly sandy loam, with slopes of 5 to 15 percent (Ab); the soils in the southern portion of the site are mapped as Cloquallum silt loam, 5 to 15 percent slopes (Cc). The survey describes the Alderwood gravelly sandy loam as follows: This is the most extensive, soil of the Alderwood series. It occupies undulating to rolling moraines. In undisturbed areas a 1- to 2-inch mat of very dark brown, acid organic matter is on the surface. This grades to a thin, dark grayish-brown, highly organic mineral soil. The surface soil consists of a friable, brown, medium acid gravelly sandy loam 8 to 13 inches deep. It has a weak granular structure and contains numerous rounded shot. Below the surface soil, to depths ranging from 18 to 24 inches, is a pale-brown gravelly sandy loam that is very friable, is single grained; and contains small to moderate amounts of shot. Between this layer and the cemented till is a 3- to 10-inch layer of very pale brown gravelly sandy loam. It contains no shot and is firmer but has the same texture as the layer above. However, it is faintly to distinctly spotted and horizontally streaked with brown and yellow. The cemented till consists of light-gray, gravelly sandy loam, and it normally occurs at depths ranging from 24 to 32 inches. It is impermeable to roots and very slowly permeable to water. The first few inches is usually laminated and streaked with reddish brown and yellow. Below this, to a depth of many feet, the till is uniformly cemented,fairly uniform light gray, and medium to strongly acid. A thin mat of roots often lies over the till. The cemented substratum tends to restrict the rapid downward movement of moisture. The survey describes the Cloquallum silt loam as follows: This soil is readily accessible and is the most extensive in the series. It is gently rolling to rolling. The surface soil is a medium acid, friable, moderately granular, pale-brown to brown silt loam that is 8 to' 12 inches thick It contains a moderate amount of rounded shot that are pale brown on the outside but reddish brown on the inside. The subsurface laver is friable, more coarsely granular, pale-brown and reddish-brown silt loam ranging from 1 to 12 inches in 10011 Blomberg Street SW,Olympia,WA 98512 2 Phone#(360)754-4612 Fax#(360)754-4848 GEOTECHNICAL TESTING LABORATORY thickness. This laver contains less shot than the surface layer, and it is faintly mottled with yellowish brown. Its thickness is fairly uniform in some. areas but extremely variable in others. The subsurface layer grades to a subsoil of light-brown to brown silt loam that is mottled with very pale brown and light reddish brown. It is firm, contains no shot, and is more clayey than the surface soil. At depths of 24 to 28 inches the silt loam grades to firm, very pale brown and brownish yellow, laminated silt, light clay, and very fine sand. The root channels are stained with rust brown, and the laminated planes, with yellowish brown. CLOSING We have completed infiltration testing in the area of the proposed dispersal area. Our testing and research indicates the infiltration rate of the Alderwood gravelly sandy loam is approximately 2 to 5 inches/hour, using a factor of safety of 2. Should you have any further question regarding procedures used in conducting this testing, or have any further testing needs, do not hesitate to call. Respectfully Submitted, GEOTECHNICAL TESTING LABORATORY Blaise Jelinek, EIT Hydrological Engineer 10011 Blomberg Street SW,Olympia,WA 98512 3 Phone#(360)7544612 Fax#(360)7544848 GEOTECHNICAL TESTING LABORATORY Infiltration Test Locations 0 Of o ° RM-4 0 0 0 10011 Blomberg Street SW,Olympia,WA 98512 4 Phone#(360)754-4612 Fax#(360)7544948 Michael O'Day-Equestrian Riding Arena SUPPORTING CALCULATIONS Marley L.Young,Consulting Engineer Project No.2006-33 7/13/06 8:31 :29 pm Marley Young Engineer page 1 MICHAEL O'DAY 4771 E SR3 Horse Arena j Stormwater Control Proj 2006-33 ---------- BASIN SUMMARY BASIN ID: 2ra NAME: 6 month storm 1/2 roof SBUH METHODOLOGY TOTAL AREA. . . . . . . : 0.28 Acres BASEFLOWS: 0.00 cfs RAINFALL TYPE. . . . : TYPElA PERV IMP PRECIPITATION. . . . : 2.40 inches AREA. . : 0.00 Acres 0 .28 Acres TIME INTERVAL. . . . : 5.00 min CN. . . . : 0.00 98.00 TC. . . . . 0.00 min 5. 00 min ABSTRACTION COEFF: 0.20 PEAK RATE: 0. 14 cfs VOL: 0.05 Ac-ft TIME: 480 min BASIN ID: 2rb NAME: 2year storm 1/2 roof SBUH METHODOLOGY TOTAL AREA. . . . . . . : 0.28 Acres BASEFLOWS: 0.00 cfs RAINFALL TYPE. . . . : TYPEIA PERV IMP PRECIPITATION. . . . : 3. 75 inches AREA. . : 0. 00 Acres 0.28 Acres TIME INTERVAL. . . . : 5.00 min CN. . . . : 0.00 98.00 TC. . . . . 0. 00 min 5.00 min ABSTRACTION COEFF: 0.20 PEAK RATE: 0.22 cfs VOL: 0.08 Ac-ft TIME: 480 min BASIN ID: 2rc NAME: 10year storm 1/2 roof SBUH METHODOLOGY TOTAL AREA. . . . . . . : 0.28 Acres BASEFLOWS: 0.00 cfs RAINFALL TYPE. . . . : TYPElA PERV IMP PRECIPITATION. . . . : 5.20 inches AREA. . : 0.00 Acres 0. 28 Acres TIME INTERVAL. . . . : 5.00 min CN. . . . : 0.00 98.00 TC. . . . . 0.00 min 5.00 min ABSTRACTION COEFF: 0.20 PEAK RATE: 0.31 cfs VOL: 0. 12 Ac-ft TIME: 480 min BASIN ID: 2rd NAME: 100year storm 1/2 roof SBUH METHODOLOGY TOTAL AREA. . . . . . . : 0.28 Acres BASEFLOWS: 0.00 cfs RAINFALL TYPE. . . . : TYPElA PERV IMP PRECIPITATION. . . . : 7.25 inches AREA. . : 0 .00 Acres 0.28 Acres TIME INTERVAL. . . . : 5.00 min CN. . . . : 0.00 98 .00 TC. . . . . 0.00 min 5.00 min ABSTRACTION COEFF: 0.20 PEAK RATE: 0.43 cfs VOL: 0. 16 Ac-ft TIME: 480 min 7/13/06 8:31:29 pm Marley Young Engineer page 2 MICHAEL O'DAY 4771 E SR3 Horse Arena Stormwater Control Proj 2006-33 � BASIN SUMMARY=-===-________-_____________ BASIN ID: A NAME: 6 month storm pre project SBUH METHODOLOGY TOTAL AREA. . . . . . . : 0.83 Acres BASEFLOWS: 0.00 cfs RAINFALL TYPE. . . . : TYPEIA PERV IMP PRECIPITATION. . . . : 2.40 inches AREA. . : 0.83 Acres 0.00 Acres TIME INTERVAL. . . . : 5.00 min CN. . . . : 85.00 0.00 TC. . . . . 10.00 min 0 .00 min ABSTRACTION COEFF: 0.20 PEAK RATE: 0. 18 cfs VOL: 0.08 Ac-ft TIME: 480 min BASIN ID: B NAME: 2 year storm SBUH METHODOLOGY TOTAL AREA. . . . . . . : 0.83 Acres BASEFLOWS: 0.00 cfs RAINFALL TYPE. . . . : TYPEIA PERV IMP PRECIPITATION. . . . : 3.75 inches AREA. . : 0.83 Acres 0.00 Acres TIME INTERVAL. . . . : 5.00 min CN. . . . : 85.00 0.00 TC. . . . : 10.00 min 0 .00 min ABSTRACTION COEFF: 0.20 PEAK RATE: 0.40 cfs VOL: 0. 15 Ac-ft TIME: 480 min BASIN ID: C NAME: 10 year storm SBUH METHODOLOGY TOTAL AREA. . . . . . . : 0.83 Acres BASEFLOWS: 0.00 cfs RAINFALL TYPE. . . . : TYPEIA PERV IMP PRECIPITATION. . . . : 5.20 inches AREA. . : 0.83 Acres 0.00 Acres TIME INTERVAL. . . . : 5.00 min CN. . . . : 85.00 0.00 TC. . . . : 10.00 min 0.00 min ABSTRACTION COEFF: 0.20 PEAK RATE: 0.66 cfs VOL: 0.24 Ac-ft TIME: 480 min BASIN ID: D NAME: 100 year storm SBUH METHODOLOGY TOTAL AREA. . . . . . . : 0.83 Acres BASEFLOWS: 0.00 cfs RAINFALL TYPE. . . . : TYPEIA PERV IMP PRECIPITATION. . . . : 7.25 inches AREA. . : 0.83 Acres 0.00 Acres TIME INTERVAL. . . . : 5.00 min CN. . . . : 85.00 0.00 TC. . . . : 10.00 min 0.00 min ABSTRACTION COEFF: 0.20 PEAK RATE: 1.02 cfs VOL: 0.38 Ac-ft TIME: 480 min 7/13/06 8:31 :29 pm Marley Young Engineer page 3 MICHAEL O'DAY 4771 E SR3 Horse Arena Stormwater Control Proj 2006-33 BASIN SUMMARY BASIN ID: da NAME: 6 month storm grass slope SBUH METHODOLOGY TOTAL AREA. . . . . . . : 0.28 Acres BASEFLOWS: 0.00 cfs RAINFALL TYPE. . . . : TYPElA PERV IMP PRECIPITATION. . . . : 2.40 inches AREA. . : 0.28 Acres 0.00 Acres TIME INTERVAL. . . . : 5.00 min CN. . . . : 87.00 0 .00 TC. . . . . 5.00 min 0.00 min ABSTRACTION COEFF: 0.20 PEAK RATE: 0.08 cfs VOL: 0.03 Ac-ft TIME: 480 min BASIN ID: db NAME: 2 Year storm grass slope SBUH METHODOLOGY TOTAL AREA. . . . . . . : 0.28 Acres BASEFLOWS: 0.00 cfs RAINFALL TYPE. . . . : TYPEIA PERV IMP PRECIPITATION. . . . : 3. 75 inches AREA. . : 0.28 Acres 0.00 Acres TIME INTERVAL. . . . : 5.00 min CN. . . . : 87.00 0.00 TC. . . . . 5.00 min 0.00 min ABSTRACTION COEFF: 0.20 PEAK RATE: 0. 16 cfs VOL: 0.06 Ac-ft TIME: 480 min BASIN ID: do NAME: 10 Year storm grass slope SBUH METHODOLOGY TOTAL AREA. . . . . . . : 0.28 Acres BASEFLOWS: 0.00 cfs RAINFALL TYPE. . . . : TYPElA PERV IMP PRECIPITATION. . . . : 5.20 inches AREA. . : 0.28 Acres 0.00 Acres TIME INTERVAL. . . . : 5.00 min CN. . . . : 87.00 0.00 TC. . . . : 5.00 min 0.00 min ABSTRACTION COEFF: 0.20 PEAK RATE: 0.25 cfs VOL: 0.09 Ac-ft TIME: 480 min BASIN ID: dd NAME: 100 Year storm grass slope SBUH METHODOLOGY TOTAL AREA. . . . . . . : 0.28 Acres BASEFLOWS: 0.00 cfs RAINFALL TYPE. . . . : TYPEIA PERV IMP PRECIPITATION. . . . : 7.25 inches AREA. . : 0.28 Acres 0.00 Acres TIME INTERVAL. . . . : 5.00 min CN. . . . : 87.00 0.00 TC. . . . . 5.00 min 0.00 min ABSTRACTION COEFF: 0.20 PEAK RATE: 0.37 cfs VOL: 0.13 Ac-ft TIME: 480 min 7/13/06 8:31:29 pm Marley Young Engineer page 4 MICHAEL O'DAY 4771 E SR3 Horse Arena Stormwater Control Proj 2006-33 BASIN SUMMARY BASIN ID: ra NAME: 6 month storm 1/8th roof SBUH METHODOLOGY TOTAL AREA. . . . . . . : 0. 14 Acres BASEFLOWS: 0.00 cfs RAINFALL TYPE. . . . : TYPEIA PERV IMP PRECIPITATION. . . . : 2.40 inches AREA. . : 0.00 Acres 0. 14 Acres TIME INTERVAL. . . . : 5.00 min CN. . . . : 0.00 98.00 TC. . . . : 0.00 min 5.00 min ABSTRACTION COEFF: 0.20 PEAK RATE: 0.07 cfs VOL: 0.03 Ac-ft TIME: 480 min N D• r NAME: 2 Year storm 1 8th roo BASIN I b / SBUH METHODOLOGY TOTAL AREA. . . . . . . : 0.14 Acres BASEFLOWS: 0.00 cfs RAINFALL TYPE. . . . : TYPEIA PERV IMP PRECIPITATION. . . . : 3.75 inches AREA. . : 0.00 Acres 0.14 Acres TIME INTERVAL. . . . : 5.00 min CN. . . . : 0.00 98.00 TC. . . . . 0.00 min 5.00 min ABSTRACTION COEFF: 0.20 PEAK RATE: 0. 11 cfs VOL: 0.04 Ac-ft TIME: 480 min BASIN ID: rc NAME: 10 Year storm 1/8th roo SBUH METHODOLOGY TOTAL AREA. . . . . . . : 0.14 Acres BASEFLOWS: 0.00 cfs RAINFALL TYPE. . . . : TYPEIA PERV IMP PRECIPITATION. . . . : 5.20 inches AREA. . : 0.00 Acres 0. 14 Acres TIME INTERVAL. . . . : 5.00 min CN. . . . : 0.00 98.00 TC. . . . . 0.00 min 5.00 min ABSTRACTION COEFF: 0.20 PEAK RATE: 0. 15 cfs VOL: 0.06 Ac-ft TIME: 480 min BASIN ID: rd NAME: 100 Year storm 1/8th roo SBUH METHODOLOGY TOTAL AREA. . . . . . . : 0.14 Acres BASEFLOWS: 0.00 cfs RAINFALL TYPE. . . . : TYPEIA PERV IMP PRECIPITATION. . . . : 7.25 inches AREA. . : 0.00 Acres 0.14 Acres TIME INTERVAL. . . . : 5.00 min CN. . . . : 0.00 98.00 TC. . . . . 0.00 min 5.00 min ABSTRACTION COEFF: 0.20 PEAK RATE: 0.21 cfs VOL: 0.08 Ac-ft TIME: 480 min 7/13/06 8:31:29 pm Marley Young Engineer page 5 MICHAEL O'DAY 4771 E SR3 Horse Arena Stormwater Control Proj 2006-33 STORAGE STRUCTURE LIST 3`3% Vot©� TRAPEZOIDAL BASIN ID No. Troofl 0 PE:r-) Description: equal section of roof -rp-E-K)C-w 3.50 Length: 110.00 ft. Width: -1-36 ft. Side Slope 1 : 0 Side Slope 3: 0 Side Slope 2: 0 Side Slope 4: 0 Infiltration Rate: 20.00 min/inch TRAPEZOIDAL BASIN ID No. Troof2 Description: equal section of roof Length: 190.00 ft. Width: �-1-d ft. . Side Slope 1: 0 Side Slope 3: 0 Side Slope 2: 0 Side Slope 4: 0 Infiltration Rate: 30.00 min/inch TRAPEZOIDAL BASIN ID No. Troof3 Description: equal section of roof Length: 220.00 ft. Width: 1:--16- ft. Side Slope 1 : 0 Side Slope 3: 0 Side Slope 2 : 0 Side Slope 4: 0 Infiltration Rate: 30.00 min inch TRAPEZOIDAL BASIN ID No. Troof4 Description: equal section of roof Length: 200.00 ft. Width: 1 16- ft. 73 j Side Slope 1 : 0 Side Slope 3: 0 Side Slope 2: 0 Side Slope 4: 0 Infiltration Rate: 20.00 min/inch 7/13/06 8:31:29 pm Marley Young Engineer page 6 MICHAEL O'DAY 4771 E SR3 Horse Arena Stormwater Control Proj 2006-33 DISCHARGE STRUCTURE LIST OVERFLOW WEIR ID No. W Description: weir for calculation only Ratio (h:1v) : 3.2100 Weir length: 3.0000 ft. El : 100.00 ft. Weir Increm: 0.1 7/13/06 8:54: 31 pm Marley Young Engineer page 1 MICHAEL O'DAY 4771 E SR3 Horse Arena Stormwater Control Proj 2006-33 DISCHARGE STRUCTURE LIST OVERFLOW WEIR ID No. W Description: weir for calculation only Ratio (h:lv) : 3.2100 Weir length: 3.0000 ft. El: 100.00 ft. Weir Increm: 0.10 7/13/06 8. 29 .45 pm Marley Young Engineer page 1 MICHAEL O'DAY 4771 E SR3 Horse Arena Stormwater Control Proj 2006-33 HISTORY OF HYDROGRAPH ACTIVITY Date of Session: 7/13/06 8:29:36 pm CLEAREIS REMARK ra thru rd are the 6 ,onth, 2 year, 10 year and 100 year storm events over 1/2 of the roof area. Dividing the roof into two parts was down to determine the smallest diam. drain pipe. LSTEND MOVE ra to 1 0.0688 cfs 0.0253 ac-ft 8.00 hrs MOVE rb to 2 0.1095 cfs 0.0409 ac-ft 8.00 hrs MOVE rc to 3 0.1528 cfs 0.0578 ac-ft 8.00 hrs MOVE rd to 4 0.2138 cfs 0.0817 ac-ft 8.00 hrs REMARK Troofl is the rock filled trench running below the north roof line. Troofl is 110' long (half the roof length). Troofl provides some infiltration. The four PkStg and OutQ represent the four storm events. LSTEND LPOOL 1 "6MO" 1 1 Troofl W 5 Description MatchQ PeakQ Sto Dis PkStg OutQ hyd Volume 6MO 0.07 0.07 Yraofl W 99.31 0.03 5 167.41 cf LPOOL 2 "2YR" 2 2 Troofl W 6 Description MatchQ PeakQ Sto Dis PkStg OutQ hyd Volume 2YR 0.11 0.11 Troofl W 100.06 0.11 6 263.03 cf LPOOL 3 110YR" 3 3 Troofl W 7 Description MatchQ PeakQ Sto Dis PkStg OutQ hyd Volume 10YR 0.15 0.15 Troofl W 100.03 0.15 7 259.52 cf LPOOL 4 "100YR" 4 4 Troofl W 8 Description MatchQ PeakQ Sto Dis PkStg OutQ hyd Volume 100YR 0.21 0.21 Troofl W 100.05 0.21 8 261.85 cf REMARK The four SPLIT below again represent the four storm events. The top cfs flows above ground and the second # infiltrates to ground. LSTEND SPLIT W 1 13 17 0.0000 cfs 0.0000 ac-ft 0.00 hrs 0.0291 cfs 0.0253 ac-ft 8.67 hrs SPLIT W 2 14 18 0.1095 cfs 0.0022 ac-ft 8.08 hrs 0.0399 cfs 0.0387 ac-ft 8.25 hrs 7/13/06 8:29:45 pm Marley Young Engineer page Z MICHAEL O'DAY 4771 E SR3 Horse Arena Stormwater Control Proj 2006-33 ----------------- --------- - HISTORY OF HYDROGRAPH ACTIVITY SPLIT W 3 15 19 0.1124 cfs 0.0072 ac-ft 8.08 hrs 0.0403 cfs 0.0502 ac-ft 8.08 hrs SPLIT W 4 16 20 0.1730 cfs 0.0184 ac-ft 8.08 hrs 0.0405 cfs 0.0620 ac-ft 8.08 hrs REMARK Below the storm discharge from the second half to the north side of the arena is is added to the above ground flow shown earlier. LSTEND ADD 1 13 9 0.0688 cfs 0.0253 ac-ft 8.00 hrs ADD 2 14 10 0.1982 cfs 0.0432 ac-ft 8.08 hrs ADD 3 15 11 0.2648 cfs 0.0650 ac-ft 8.00 hrs ADD 4 16 12 0.3867 cfs 0.1001 ac-ft 8.00 hrs ZERO 1 8 REMARK Troof2 is the rock filled trench that located below the remaining northerly roof eave and continues along the east end of the arena to the south east corner of the arena. Troof2 is 190' long and provides some infiltation. LSTEND LPOOL 1 "6MO" 9 9 Troof2 W 5 Description MatchQ PeakQ Sto Dis PkStg OutQ hyd Volume 6MO 0.07 0.07 Troof2 W 98.85 0.03 5 188.42 cf LPOOL 2 "29" 10 10 Troof2 W 6 Description MatchQ PeakQ Sto Dis PkStg OutQ hyd Volume 2YR 0.20 0.20 Troof2 W 99.99 0.05 6 438.74 cf LPOOL 3 "10YR" 11 11 Troof2 W 7 Description MatchQ PeakQ Sto Dis PkStg OutQ hyd Volume 10YR 0.26 0.26 Troof2 W 100.08 0.26 7 459.14 cf LPOOL 4 "100YR" 12 12 Troof2 W 8 Description MatchQ PeakQ Sto Dis PkStg OutQ hyd Volume 100YR 0.39 0.39 Troof2 W 100.10 0.39 8 463.05 cf REMARK In the SPLIT the top $ cfs will flow southwesterly and the bottom # will infiltate. Note that the 6 month storm event has infiltated to ground and none is available to discharge further down the pipe. LSTEND i/IJ/ub 8:29:45 pm Marley Young Engineer page 3 MICHAEL O'DAY 4771 E SR3 Horse Arena Stormwater Control Proj 2006-33 HISTORY OF HYDROGRAPH ACTIVITY SPLIT W 1 13 17 0.0000 cfs 0.0000 ac-ft 0.00 hrs 0.0253 cfs 0.0252 ac-ft 9.08 hrs SPLIT W 2 14 18 0.0000 cfs 0.0000 ac-ft 0.00 hrs 0.0454 cfs 0.0430 ac-ft 8.92 hrs SPLIT W 3 15 19 0.2648 cfs 0.0114 ac-ft 7.92 hrs 0.0468 cfs 0.0527 ac-ft 8.17 hrs SPLIT W 4 16 20 0.3386 cfs 0.0312 ac-ft 8.08 hrs 0.0474 cfs 0.0664 ac-ft 8.08 hrs REMARK the total south half of the roof area (220 a 40) is shown as 2ra thru 2rd, (the four storm events). These discharges are collect in the trench below the arena south eave. LSTEND MOVE 2ra to 1 0.1377 cfs 0.0506 ac-ft 8.00 hrs MOVE 2rb to 2 0.2189 cfs 0.0819 ac-ft 8.00 hrs MOVE 2rc to 3 0.3055 cfs 0.1156 ac-ft 8.00 hrs MOVE 2rd to 4 0.4276 cfs 0.1633 ac-ft 8.00 hrs REMARK Troof3 is the rock filled trench that located below the southerly roof eave and will connect with Troof2 at the south east corner of the arena. Troof3 is 220' long and provides some infiltation. LSTEND LPOOL 1 "6M0" 1 1 Troof3 W 5 Description MatchQ PeakQ Sto Dis PkStg OutQ hyd Volume 6M0 0.14 0.14 Troof3 W 99.79 0.05 5 456.57 cf LPOOL 2 "2YR" 2 2 Troof3 W 6 Description MatchQ PeakQ Sto Dis PkStg OutQ hyd Volume 2YR 0.22 0.22 Troof3 W 100.08 0.22 6 529.64 cf LPOOL 3 "IOYR" 3 3 Troof3 W 7 Description MatchQ PeakQ Sto Dis PkStq OutQ hyd Volume 10YR 0.31 0.31 Troof3 W 100.08 0.31 7 529.69 cf LPOOL 4 "100YR" 4 4 Troof3 W 8 Description MatchQ PeakQ Sto Dis PkStg OutQ hyd Volume 7/13/06 8 :29 :45 pm Marley Young Engineer page 4 MICHAEL O'DAY 4771 E SR3 Horse Arena Stormwater Control Proj 2006-33 HISTORY OF HYDROGRAPH ACTIVITY 100YR 0.43 0.43 Troof3 W 100.13 0.43 8 544.81 cf REMARK In the SPLIT below the top # cfs will flow southwesterly and the bottom # will infiltate. LSTEND SPLIT W 1 9 17 0.0000 cfs 0.0000 ac-ft 0.00 hrs 0.0485 cfs 0.0502 ac-ft 9.17 hrs SPLIT W 2 10 18 0.2189 cfs 0.0118 ac-ft 7.83 hrs 0.0534 cfs 0.0681 ac-ft 8.25 hrs SPLIT W 3 11 19 0.2510 cfs 0.0271 ac-ft 8.08 hrs 0.0543 cfs 0.0842 ac-ft 8.08 hrs SPLIT W 4 12 20 0.4276 cfs 0.0616 ac-ft 8.00 hrs 0.0549 cfs 0.0949 ac-ft 7.92 hrs ZERO 17 20 REMARK The ADD below is combining the total runoff from the roof arena that has not been infiltrated. These flows are directed south westerly in another trench. LSTEND ADD 9 13 17 0.0000 cfs 0.0000 ac-ft 0.00 hrs ADD 10 14 18 0.2189 cfs 0.0118 ac-ft 7.83 hrs ADD 11 15 19 0.5158 cfs 0.0384 ac-ft 8.08 hrs ADD 12 16 20 0.7662 cfs 0.0928 ac-ft 8.08 hrs REMARK Troof4 is the rock filled trench that located along the grass slope and connects with Troof2 and Troof3 at the south east corner of the arena. Troof4 is 200' long and provides some infiltation. LSTEND LPOOL 1 16MO" 17 17 Troof4 W 5 Description MatchQ PeakQ Sto Dis PkStg OutQ hyd Volume 6M0 0.00 0.00 Troof4 W 98.00 0.00 5 0.00 cf LPOOL 2 "2YR" 18 18 Troof4 W 6 Description MatchQ PeakQ Sto Dis PkStg OutQ hyd Volume 2YR 0.22 0.22 Troof4 W 99.30 0.05 6 301.79 cf 7/13/06 8:29 :45 pm Marley Young Engineer page 5 MICHAEL O'DAY 4771 E SR3 Horse Arena Stormwater Control Proj 2006-33 HISTORY OF HYDROGRAPH ACTIVITY LPOOL 3 "IOYR" 19 19 Troof4 W 7 Description MatchQ PeakQ Sto Dis PkStg OutQ hyd Volume IOYR 0.52 0.52 Troof4 W 100.14 0.52 7 496.88 cf LPOOL 4 "100YR" 20 20 Troof4 W 8 Description MatchQ PeakQ Sto Dis PkStg OutQ hyd Volume 100YR 0.77 0.77 Troof4 W 100.17 0.77 8 502.77 cf REMARK In the SPLIT the top # cfs will flow southerly into the trees and the bottom # will infiltate. Note that the 6 month storm event has infiltated to ground and none is available to discharge further down the pipe. LSTEND SPLIT W 1 9 13 0.0000 cfs 0.0000 ac-ft 0.00 hrs 0.0000 cfs 0.0000 ac-ft 0.00 hrs SPLIT W 2 10 14 0.0000 cfs 0.0000 ac-ft 0.00 hrs 0.0525 cfs 0.0118 ac-ft 8.42 hrs SPLIT W 3 11 15 0.5158 cfs 0.0125 ac-ft 8.17 hrs 0.0751 cfs 0.0255 ac-ft 8.25 hrs SPLIT W 4 12 16 0.7662 cfs 0.0456 ac-ft 8.17 hrs 0.0762 cfs 0.0472 ac-ft 8.08 hrs REMARK The da thru dd is the four storm events on the area of the grass slope between the grass slope and the arena. This area is expected to sheet flow into the trees. LSTEND MOVE da to 1 0.0758 cfs 0.0286 ac-ft 8.00 hrs MOVE db to 2 0.1563 cfs 0.0561 ac-ft 8.00 hrs MOVE do to 3 0.2464 cfs 0.0875 ac-ft 8.00 hrs MOVE dd to 4 0.3747 cfs 0.1332 ac-ft 8.00 hrs REMARK Below the final roof runoff and the grass slope runoff are combined for a total. Note - all the pipes are to be perforated, and the last trench (Troof4) is expected to fill to capacity and sheet flow to the trees. The trench should be as level as practical. -i/1.i/Ub b:Z9 :4b pm Marley Young Engineer page 6 MICHAEL O'DAY 4771 E SR3 Horse Arena Stormwater Control Proj 2006-33 HISTORY OF HYDROGRAPH ACTIVITY These four ADD 1 cfs thru ADD 4 cfs represent the four storm events and must be compared to A thru D below. LSTEND ADD 1 9 13 0.0758 cfs 0.0286 ac-ft 8.00 hrs ADD 2 10 14 0.1563 cfs 0.0561 ac-ft 8.00 hrs ADD 3 11 15 0.6552 cfs 0.0999 ac-ft 8.17 hrs ADD 4 12 16 0.9998 cfs 0.1789 ac-ft 8.00 hrs REMARK A thru D are the calculated Pre developed runoff. As per the `manual' the Post- runoff must not exceed the Pre developed runoff. Note- no stream are in the area, however the Stream Bank Erosion Control requirement is satisfied. LSTEND MOVE A to 1 0.1814 cfs 0.0755 ac-ft 8.00 hrs MOVE B to 2 0.4022 cfs 0.1535 ac-ft 8.00 hrs MOVE C to 3 0.6569 cfs 0.2440 ac-ft 8.00 hrs MOVE D to 4 1.0246 cfs 0.3772 ac-ft 8.00 hrs REMARK NOTE - A thru D cfs are greater than the four ADD immediately above. O.K. LSTEND End program file E:\EGENIO-1\06-330DA.pgm REVIEW OF PIPE SIZE, PIPE SLOPE AND MAXIMUM VERSUS ACTUAL CFS A A B C D E F G H 1 J 1 PIPES RUNNING 80%FULL USING PVC PIPE 2 Pi Des that run at 80%full nun at full ca as Revised 8/15101 3 4 Q= 1.486/n "Rh^2/3 t S^1/2'Area I= area of water inpiw--±-- 5 1SA1/2 = slope of pipe ft/ft to the 1/2 power 6 1 RhA2/3 = h dralic radius to the 2/3 ower 1.4Wn if n= 0.013 then 1.486/n= 114.3077 8 As a reference 9 TABLE 3 AREA WETTED PERIMETER AND HYDRAULIC RADIUS 10 OF PARTIALLY FILLED CIRCULAR PIPE 11 Section 7.3- Pace 138; Book-Hydraulics of Culverts by Hendrickson Jr 12 Published bv the American Concrete Pipe Association 1957 13 14 d/D = 0.8 80% of the diameter filled with water 15 area/DA21 0.6736 factor when d/D= 0.8 16 Wet. er./D - 2.2143 factor when d/D= 0.8 17 h d.rad./D = 0.3042 factor when d/D= 0.8 18 then 19 pipel slope= Q= V= pipe Slope Q = V = 20 Diam. ft/ft cis velocity Diam ftfft cis velocity 21 3 0.0065 0.070 1.6528 4 0.0065 0.150 2.0024 22 3 0.01 0.086 2.0501 4 0.01 0.186 2.4837 23 3 0.015 0.106 2.5108 4 0.02 0.263 3.5125 24 3 0.02 0.122 2.8992 4 0.04 0.372 4.9674 25 3 0.03 0.149 3.5508 4 0.06 0.455 6.0838 26 1 3 0.04 0.173 4.1001 4 0.07 0.492 6.5713 27 1 3 0.05 0.193 4.5841 4 0.11 0.588 7.8542 28 3 0.06 0.211 5.0216 4 0.15 0.720 9.6194 29 3 0.07 0.228 5.4240 4 0.25 0.929 12.4186 30 31 6 0.004 0.347 2.0587 8 0.004 0.747 2.4941 32 6 0.005 0.388 2.3017 8 0.005 0.835 2.7885 33 6 0.006 0.425 2.5213 8 0.006 0.915 3.0547 34 6 0.01 0.548 3.2550 8 0.00867 1.099 3.6720 35 6 0.02 0.775 4.6033 8 0.01 1.181 3.9436 36 6 0.03 0.9491 5.6379 8 0.01286 1.339 4.4721 37 6 0.07 1.450 8.6120 8 0.015 1.446 4.8299 38 6 0.1 1.733 10.2933 8 0.03 2.045 6.8305 39 6 0.15 2.123 12.6067 8 0.04 2.361 7.8871 40 41 10 0.0028 1.133 2.4216 12 0.0022 1.633 2.4241 42 10 0.003 1.173 2.5066 12 0.005 2.462 3.6545 43 10 0.004 1.354 2.8944 12 0.0422 7.152 10.6169 44 10 0.006 1.658 3.5449 12 0.0642 8.821 13.0951 45 46 18 0.0012 3.556 2.3463 24 0.0038 13.630 5.0585 47 18 0.003 5.623 3.7098 24 0.005 15.634 5.8025 48 18 0.0175 13.580 8.9601 24 0.02 31.268 11.6050 49 181 0.02 14.518 9.5788 24 0.032 39.552 14.6793 50