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Home My WebLink About20080162 Ver 1_Stormwater Info_20080512 CAVANAU G H Solutions through integrity and partnership lb 8-0ILPZ May 9, 2008 Ms. Sue Homewood NC DENR Division of Water Quality 585 Waughtown Street Winston-Salem, NC 27107 Dear Sue, Mq y 12 2008 `/ DSAND 3T p8?A e Please find attached the revised plans and calculations for the Ira Myers Hwy 18 Commercial Building stormwater submittal. The following is a detailed explanation of the comments received in Steve Tedder's letter of April 17, 2008: 1. The volume of the forebay has not been designed in accordance with the Division's Stormwater BMP manual. Please redesign so that the forebay volume is adequately sized as 20% of the total volume. We have redesigned the basin and forebay and the forebay is now 21.27% of the total volume. 2. Please provide a complete sectional view of the stormwater pond including a cross-section of the entire pond. Please note that the interior slopes of the pond above the vegetative shelf must be designed (and called out on the plans) at 3:1 slopes. This is not noted on the drawings that have been submitted. The complete cross-section has been added to the plans and the 3:1 slopes have been called out on the plans. 3. Please provide a more detailed planting plan for the pond. Per the BMP manual "the planting plan should provide specifications for the selection of vegetation, its installation, and the post-installation care for the vegetated shelf, the 3:1 side slopes and the immediately surrounding areas. We have modified the vegetative shelf planting specification to include post- installation care. Additionally, we have added planting soil specifications and a maintenance table. 4. Please provide a pond that is designed to have a length to width ration of 1.5:1 minimum as noted in the BMP manual. The pond has been redesigned to meet the minimum requirement. 5. The average depth of the permanent pool is insufficient per the calculation worksheet submitted. Please note that this is average depth, not the maximum depth in a specific area. This depth should not include the 1 foot that should be provided at the bottom of the pond for sediment storage. We have modified the designed to account for the average depth. This value has been used to recalculate the required surface area. 6. The average depth must be utilized to properly calculate the Surface Area to Drainage Area calculation using Tables 10-1 through 10-4. Please re-verify this calculation. Per response to Comment #5, this recalculation has been included. Please provide a complete construction sequence that clearly indicates all construction phases of this project with regards to the stormwater pond. This must include site grading, scheduling of the pond construction and protection of the pond during construction phases and/or use and restoration of the pond during construction. The required items checklist indicates this pond will not be used as a sediment and erosion control pond, however the plans submitted note that it will be used. You must determine this information accurately and then provide details regarding use or protection during site development. We have included a construction sequence and included in that are notes relative to the use of the basin as an erosion control measure and its conversion to a permanent pond, post-construction. We hope that you find the revised submittal to be in accordance with all regulations and await a successful conclusion to this phase of the project. Please do not hesitate to contact me should there be additional questions. Sincerely, CAVANAUGH & SSOCIATES, P.A. Tory N. W goner, P.E. Cc: Ian McMillan, NCDWQ Ira Myers Michael Brame, ECS Carolinas, LLP am CAVANAU G H o g - o l 1.0 D- Stormwater calcul For Ira Myers Prop -1 ¦. SEAL Design Staff: 4 33174 : 4? Will J. Jernigan, P.E. Z Tory N. Wagoner, P.E. Cavanaugh & Associates, ?v May 2008 %20 (FORTH TFtAOC STREET, SUITE 3020 WINSTON-SALEM. NORTH CAROLINA 271 01 • 336.759.9001 0 336.759, 1005 WWW.CAVANAUGHSOLUTIONS.00M Permit No (to be provided by DWQ) IL REQUI !f TIf#9"C C S, Please indicate the page or plan sheet numbers where the supporting documentation can be found. An incomplete submittal package will result in a request for additional information. This will delay final review and approval of the project. Initial in the space provided to indicate the following design requirements have been met. If the applicant has designated an agent, the agent may initial below. If a requirement has not been met, attach justification. Pagel Plan Initials Sheet No. - Nvv C .l .0 1. Plans (1" - 50' or larger) of the entire site showing: - Design at ultimate build-out, - Off-site drainage (if applicable), - Delineated drainage basins (include Rational C coefficient per basin), - Basin dimensions, - Pretreatment system, - High flow bypass system, - Maintenance access, - Proposed drainage easement and public right of way (ROW), - Overflow device, and - Boundaries of drainage easement. TN w C . . 0 2, Partial plan (1" = 30' or larger) and details for the wet detention basin showing: - Outlet structure with trash rack or similar, - Maintenance access, - Permanent pool dimensions, - Forebay and main pond with hardened emergency spillway, - Basin cross-section, - Vegetation specification for planting shelf, and - Filter strip. 70vV 0 3. Section view of the dry detention basin (1" = 20' or larger) showing: - Side slopes, 3:1 or lower, - Pretreatment and treatment areas, and - Inlet and outlet structures. 1NW C. 1.0 4. If the basin is used for sediment and erosion control during construction, clean out of the basin is specified on the plans prior to use as a wet detention basin. -rw w C g? tu(r%t;ong 5. A table of elevations, areas, incremental volumes & accumulated volumes for overall pond and for forebay, to verify volume provided. TNw 6 .1.0 6. A construction sequence that shows how the wet detention basin will be protected from sediment until the entire drainage area is stabilized. -Ww 7. The supporting calculations. -ro U Calo?taf;,A f 8. A copy of the signed and notarized operation and maintenance (0&M) agreement. 9. A copy of the deed restrictions (if required). 10. A soils report that is based upon an actual field investigation, soil borings, and infiltration tests. County soil maps are not an acceptable source of soils information. Form SW401-Wet Detention Basin-Rev.4 Part III. Required Items Checklist, Page 3 of 3 Table of Contents Ira Myers tnwattempt.gpw Hydraflow Hydrographs by Intelisolve 10 -Year Tuesday, May 6 2008,1:12 PM Summary Report ................................................................................................................. 1 Hydrograph Reports ........................................................................................................... 2 Hydrograph No. 2, Reservoir, stormwater ........................................................................ 2 Pond Report ................................................................................................................. 3 100 - Year Summary Report ................................................................................................................. 4 Hydrograph Reports ........................................................................................................... 5 Hydrograph No. 2, Reservoir, stormwater ........................................................................ 5 Pond Report ................................................................................................................. 6 Hydrograph Summary Report Hyd. No. Hydrograph type (origin) Peak flow (cfs) Time interval (min) Time to peak (min) Volume (cuft) Inflow hyd(s) Maximum elevation (ft) Maximum storage (cuft) Hydrograph description 1 Rational 40.95 1 10 24,571 ---- ------ ------ storm 2 Reservoir 0.13 1 20 17,330 1 1133.62 24,476 stormwater Ira Myers tnwattempt.gpw Return Period: 10 Year Tuesday, May 6 2008, 1:11 PM Hydraflow Hydrographs by Intelisolve 2 Hydrograph Plot Hydraflow Hydrographs by Intelisolve Tuesday, May 6 2008, 1:11 PM Hyd. No. 2 stormwater Hydrograph type = Reservoir Peak discharge = 0.13 cfs Storm frequency = 10 yrs Time interval = 1 min Inflow hyd. No. = 1 Max. Elevation = 1133.62 ft Reservoir name = detention Max. Storage = 24,476 cuft Storage Indication method used. Q (cfs) 50.00 stormwater Hyd. No. 2 -- 10 Yr 40.00 30.00 Hydrograph Volume = 17,330 cuft 20.00 10.00 0.00 -L 0 Q (cfs) 50.00 40.00 30.00 20.00 10.00 0.00 5 10 15 19 24 29 34 39 44 48 Time (hrs) Hyd No. 2 Hyd No. 1 Pond Report Hydraflow Hydrographs by Intelisolve Tuesday, May 6 2008, 1:11 PM Pond No. 1 - detention Pond Data Pond storage is based on known contour areas. Average end area method used. Stage / Storage Table Stage (ft) Elevation (ft) Contour area (sqft) Incr. Storage (cuft) Total storage (cuft) 0.00 1132.00 12,727 0 0 1.00 1133.00 15,756 14,242 14,242 2.00 1134.00 17,331 16,544 30,785 3.00 1135.00 18,963 18,147 48,932 3.50 1135.50 19,458 9,605 58,537 Culvert / Orifice Structures [A] [B] [C] [D] Rise (in) = 15.00 2.00 0.00 0.00 Span (in) = 15.00 2.00 0.00 0.00 No. Barrels = 1 1 0 0 Invert El. (ft) = 1125.00 1132.00 0.00 0.00 Length (ft) = 0.00 0.00 0.00 0.00 Slope (%) = 0.00 0.00 0.00 0.00 N-Value = .013 .013 .000 .000 Orif. Coeff. = 0.60 0.60 0.00 0.00 Multi-Stage = n/a Yes No No Weir Structures [A] [B] [C] [D] Crest Len (ft) = 16.00 10.00 0.00 0.00 Crest EI.(ft) = 1134.00 1134.50 0.00 0.00 Weir Coeff. = 3.33 3.33 0.00 0.00 Weir Type = Riser Rect --- --- Multi-Stage = Yes No No No Exfiltration = 0.000 in/hr (Contour) Tailwater Elev. = 0.00 ft Note: Culvert/Orifice outflows have been analyzed under inlet and outlet control. Stage (ft) 4.00 3.00 2.00 1.00 0.00 ' ' ' 0.00 Stage (ft) 4.00 3.00 2.00 1.00 0.00 5.00 10.00 15.00 20.00 25.00 30.00 35.00 40.00 45.00 50.00 55.00 Discharge (cfs) Total Q 3 Hydrograph Summary Report Hyd. No. Hydrograph type (origin) Peak flow (cfs) Time interval (min) Time to peak (min) Volume (cult) Inflow hyd(s) Maximum elevation (ft) Maximum storage (cult) Hydrograph description 1 Rational 56.54 1 10 33,927 ---- ------ ------ storm 2 Reservoir 3.07 1 19 22,886 1 1134.14 33,326 stormwater Ira Myers tnwattempt.gpw Return Period: 100 Year Tuesday, May 6 2008, 1:12 PM Hydraflow Hydrographs by Intelisolve 5 Hydrograph Plot Hydraflow Hydrographs by Intelisolve Tuesday, May 6 2008,1:12 PM Hyd. No. 2 stormwater Hydrograph type = Reservoir Peak discharge = 3.07 cfs Storm frequency = 100 yrs Time interval = 1 min Inflow hyd. No. = 1 Max. Elevation = 1134.14 ft Reservoir name = detention Max. Storage = 33,326 cuft Storage Indication method used. Hydrograph Volume = 22,886 cuft Q (cfs) 60.00 50.00 40.00 30.00 20.00 10.00 stormwater Hyd. No. 2 -- 100 Yr Q (cfs) 60.00 50.00 40.00 30.00 20.00 10.00 0.00 1n I I - I I _I I I 10.00 0 5 10 15 19 24 29 34 39 44 48 Time (hrs) Hyd No. 2 Hyd No. 1 Pond Report Hydraflow Hydrographs by Intelisolve Tuesday, May 6 2008, 1:12 PM Pond No. 1 - detention Pond Data Pond storage is based on known contour areas. Average end area method used. Stage / Storage Table Stage (ft) Elevation (ft) Contour area (sqft) Incr. Storage (cuft) Total storage (cult) 0.00 1132.00 12,727 0 0 1.00 1133.00 15,756 14,242 14,242 2.00 1134.00 17,331 16,544 30,785 3.00 1135.00 18,963 18,147 48,932 3.50 1135.50 19,458 9,605 58,537 Culvert / Orifice Structures Weir Structures [A] [B] [C] [D] [A] [B] [C] [D] Rise (in) = 15.00 2.00 0.00 0.00 Crest Len (ft) = 16.00 10.00 0.00 0.00 Span (in) = 15.00 2.00 0.00 0.00 Crest El. (ft) = 1134.00 1134.50 0.00 0.00 No. Barrels = 1 1 0 0 Weir Coeff. = 3.33 3.33 0.00 0.00 Invert El. (ft) = 1125.00 1132.00 0.00 0.00 Weir Type = Riser Rect --- Length (ft) = 0.00 0.00 0.00 0.00 Multi-Stage = Yes No No No Slope (%) = 0.00 0.00 0.00 0.00 N-Value = .013 .013 .000 .000 Orif. Coeff. = 0.60 0.60 0.00 0.00 Multi-Stage = n/a Yes No No Exfiltration = 0 .000 in/hr (Con tour) Tailwater Elev. = 0.00 ft Note: Culvert/Orifice outflows have been analyzed under inlet and outlet control. Stage (ft) 4.00 3.00 2.00 1.00 0 00 Stage / Discharge Stage (ft) 4.00 3.00 2.00 1.00 0 00 6 0.00 5.00 10.00 15.00 20.00 25.00 30.00 35.00 40.00 45.00 50.00 55.00 Total Q Discharge (cfs) EC Outlet Devices (NY DOT Dissipator Method) (for tailwater conditions greater than 0.5 ft) Outlet No. Pipe Size Velocity Equation Length (1-2) Width Rip-Rap Minimum 1Discri tlon inches (fps) Number Feet Feet Class Thickness In. 18 _%00' 3 12 6.3 Class 1 25.5 2 15 2 50. 'I 5 3.25 Class B 16 4 1 1 1 .1 f SS J _ Notes: For Multiple Culverts use 1.25 times diameter of pipe For Outlets on slopes greater than 10% use next higher equation number If "Special" appreas in the results box, another method should be used for design NC DOT Rip-Rap sizes used (T=1.5*Dmax) Appendices NEW YORK DOT DISSIPATOR METHOD FOR USE IN DEFINED CHANNELS (Source; Bank and channel lining procedures", New Yolk Depart?nent: of Transportation, Division of Design and Construction, 1971) Note: To use the following chart you must brow: (1) Q full capacity (2) Qto (3) V full (4) Vlo where Q = discharge in efs and V = Velocity in FPS. ESTIMATION OF STONE SIZE AND DIMENSIONS FOR CULVERT APRONS Step 1) Compute flow velocity Vo at culvert or paved channel outlet. Step 2) For pipe culverts Do is diameter. For pipe arch, arch and box culverts, and paved channel outlets, Do--Ao, where A.= cross-sectional area of flow at outlet. For multiple culverts, use Do=1,250o of single culvert. Step 3) For apron grades of 10015 or steeper, use recommendations For next highevzone. (Zones 1 through 6). a . U O W, 0• 10' 15- w DIAMETER (Ft.) Figure 8.06.h.1 Rev. 12193 0 APRON tM1ATERIAI o PHEVt?fT scours OLE USE L2 ALIYAYS LZ STONE FILLING (FfNE} 4 x Da STONE FILLING UGH' W B X Do? STONE FILLING (MEDIUM e x Do STONE FILLING (HEAVY) 8 x Da STONE FILLING (HEAVY] 10 x Do S70NE FILLING (HEAVYI 10 x Do. EC IAL STUDY REQUIRED (ENERGY DISSIPATORS, S7{LLING ASIN on LARGER SIZE STONNE). Fig. 8.06.b,2 Width = 3 times pipe dia. (min,) DETEP.MINATION OF STONE SIXES FOR DUMPED STONE CHANNEL LININGS AND REVETMENTS Step 1) Use figure 8.061.3 to determine maximum stone size (e.g, for 12 Fps=20" or 550 lbs. Step 2) Use figure 8.06.b,4 to determine acceptable size range for stone (for 12 FPS it is 125-500 lbs, for 75% of stone, and the maximum and minimum range in weight should be 25-5001bs.) Note: In detennining channel velocities for stone linings and revetment, use the following coefficients of roughness; Diameter Mannin's min, thickness (inches) "n" of lining (inches) Fine • 3 0,031 9 12 Light 6 0.035 12 18 ' Medium 13 0,040 18 24 Heavy 23 0.044 30 36 (Chapmels) (DISSapoton) Rev, 12193 8,06.6 Permit Number: (to be provided by DWQ) Drainage Area Number: Wet Detention Basin Inspection and Maintenance Agreement I will keep a maintenance record on this BMP. This maintenance record will be kept in a log in a known set location. Any deficient BMP elements noted in the inspection will be corrected, repaired or replaced immediately. These deficiencies can affect the integrity of structures, safety of the public, and the removal efficiency of the BMP. The wet detention basin system is defined as the wet detention basin, pretreatment including forebays and the vegetated filter if one is provided. This system (check one): LA'_' does F-1 does not This system (check one): ? does does not incorporate a vegetated filter at the outlet. incorporate pretreatment other than a forebay. Important maintenance procedures: - Immediately after the wet detention basin is established, the plants on the vegetated shelf and perimeter of the basin should be watered twice weekly if needed, until the plants become established (commonly six weeks). - No portion of the wet detention pond should be fertilized after the first initial fertilization that is required to establish the plants on the vegetated shelf. - Stable groundcover should be maintained in the drainage area to reduce the sediment load to the wet detention basin. - If the basin must be drained for an emergency or to perform maintenance, the flushing of sediment through the emergency drain should be minimized to the maximum extent practical. - Once a year, a dam safety expert should inspect the embankment. After the wet detention pond is established, it should be inspected once a month and within 24 hours after every storm event greater than 1.0 inches (or 1.5 inches if in a Coastal County). Records of inspection and maintenance should be kept in a known set location and must be available upon request. Inspection activities shall be performed as follows. Any problems that are found shall be repaired immediately. BMP element: Potential problem: How I will remediate the problem: The entire BMP Trash/ debris is resent. Remove the trash/ debris. The perimeter of the wet Areas of bare soil and/or Regrade the soil if necessary to detention basin erosive gullies have formed. remove the gully, and then plant a ground cover and water until it is established. Provide lime and a one-time fertilizer application. Vegetation is too short or too Maintain vegetation at a height of long. approximately six inches. Form SW401-Wet Detention Basin I&M-Rev.2 Permit Number: (to be provided by DWQ) Drainage Area Number: BMP element: Potential problem: How I will remediate the problem: The inlet device: pipe or The pipe is clogged. Unclog the pipe. Dispose of the swale sediment off-site. The pipe is cracked or Replace the pipe. otherwise damaged. Erosion is occurring in the Regrade the swale if necessary to swale. smooth it over and provide erosion control devices such as reinforced turf matting or riprap to avoid future problems with erosion. The forebay Sediment has accumulated to Search for the source of the a depth greater than the sediment and remedy the problem if original design depth for possible. Remove the sediment and sediment storage. dispose of it in a location where it will not cause impacts to streams or the BMP. Erosion has occurred. Provide additional erosion protection such as reinforced turf matting or riprap if needed to prevent future erosion problems. Weeds are present. Remove the weeds, preferably by hand. If pesticide is used, wipe it on the plants rather than spraying. The vegetated shelf Best professional practices Prune according to best professional show that pruning is needed practices to maintain optimal plant health. Plants are dead, diseased or Determine the source of the dying. problem: soils, hydrology, disease, etc. Remedy the problem and replace plants. Provide a one-time fertilizer application to establish the ground cover if a soil test indicates it is necessary. Weeds are present. Remove the weeds, preferably by hand. If pesticide is used, wipe it on the plants rather than spraying. The main treatment area Sediment has accumulated to Search for the source of the a depth greater than the sediment and remedy the problem if original design sediment possible. Remove the sediment and storage depth. dispose of it in a location where it will not cause impacts to streams or the BMP. Algal growth covers over Consult a professional to remove 50% of the area. and control the algal growth. Cattails, phragmites or other Remove the plants by wiping them invasive plants cover 50% of with pesticide (do not spray). the basin surface. Form SW401-Wet Detention Basin I&M-Rev.2 Permit Number: (to be provided by DWQ) Drainage Area Number: BMP element: Potential problem: How I will remediate the problem: The embankment Shrubs have started to grow Remove shrubs immediately. on the embankment. Evidence of muskrat or Use traps to remove muskrats and beaver activity is present. consult a professional to remove beavers. A tree has started to grow on Consult a dam safety specialist to the embankment. remove the tree. An annual inspection by an Make all needed repairs. appropriate professional shows that the embankment needs repair. The outlet device Clogging has occurred. Clean out the outlet device. Dispose of the sediment off-site. The outlet device is damaged Repair or replace the outlet device. The receiving water Erosion or other signs of Contact the local NC Division of damage have occurred at the Water Quality Regional Office, or outlet. the 401 Oversight Unit at 919-733- 1786. The measuring device used to determine the sediment elevation shall be such that it will give an accurate depth reading and not readily penetrate into accumulated sediments. When the permanent pool depth reads 6.15 feet in the main pond, the sediment shall be removed. When the permanent pool depth reads 1 O feet in the forebay, the sediment shall be removed. BASIN DIAGRAM ill in the blanks) 0 Permanent Pool Elevation l i 3z Sediment Removal ?? 3? YPe anen Pool - - - - - - - - - - - - - - Volume Sediment Removal Elevation Volume ??30 ------alEle tio ---------------- alum Bottom Elevatio Min. ediment Bottom Elevation I?Zy•ZS 1-ft Storage Sedimei Storage FOREBAY MAIN POND Form SW401-Wet Detention Basin I&M-Rev.2 MAY-08-2008 THU 02:37 PM Carolina Realty Incorp MAY, 7, 2008 4:16PM FCS f I i FAX NO. 13368381988 NO-4889 P. 5 pp[ltlit N1pI1b0[: ??. I (to bepawidedbyDlirQ- I aclawwIeilp and agme by my gig oUn below theft 1 am responsible for the 1 pufor>ame of *c t t to me proeedtutaa listed above, I agm to notit DWQ ofsay probi ms with the system" prior to my c wmp to the syst m or raspostlsrble party. protect tee', Mtok M'I S a o p F tt BW drainage area number; I - - P. 01/0"D print i a i i 12E?rrr - - Address;_... 9. Wit` , W164 S a"d" zrr C Note: The legsily reap4nsibis platy should not be R ham$QVMors association unless more than 90°?b of the lots have been geld and a realdent of the subdivision has bash nsowd the prasident. I, ((S f I!t?2. f 1 ? 1 o Notary Public for the Stste of 014 1 &ryfihy . County of K/if.4 , do hemby cer ft that 42A fllr/ PIS-- personally appeared before me this dory of - DD . jmd acknowledge the do execution of the forgoing wet detention basin mWnl mane requirements. Witness my hand attd ofI•ioW seal, NADINE A. LIEBERMAN NOTARY PUBLIC WILKCS COUNTY, NC My Commission Expires 81.1?12D1 SEAL My commission txpimas . _t Fom SW401-Wet Datentiion Basin I&M-Hzv,2 Permit No. (to be provided by DWQ) =GA NCDENR STORMWATER MANAGEMENT PERMIT APPLICATION FORM 401 CERTIFICATION APPLICATION FORM p??? W AT e9?G y r > y WET DETENTION BASIN SUPPLEMENT This form must be filled out, printed and submitted. The Required Items Checklist (Part III) must be printed, filled out and submitted along with all of the required information. ROJECT INEORMw' ION Project name Ira Myers Contact person Tory Wagoner Phone number 336/759-9001 Date 5/6/2008 Drainage area number 1 II D,.ESIGN; INFARM??TION Site Characteristics Drainage area 326,700.00 ft2 Impervious area 294,030.00 ft2 % impervious 90.00 0 0 Design rainfall depth 1.00 in Storage Volume: Non-SR Waters Minimum volume required 24,100.00 ft3 Volume provided 38,540.00 ft3 Storage Volume: SR Waters 24-hr runoff depth 1-yr in , Pre-development 1-yr, 24-hr runoff ft3 Post-development 1-yr, 24-hr runoff ft3 Minimum volume required ft3 Volume provided ft3 Peak Flow Calculations 1-yr, 24-hr rainfall depth 2.85 in Rational C, pre-development 0.35 (unitless) Rational C, post-development 0.90 (unitless) Rainfall intensity:1-yr, 24-hr storm 3.01 in/hr Pre-development 1-yr, 24-hr peak flow 9.54 ft3/sec Post-development 1-yr, 24-hr peak flow 0.11 ft3/sec Pre/Post 1-yr, 24-hr peak flow control -9.43 ft3/sec Basin Elevations Basin bottom elevation 1,124.25 ft Sediment cleanout elevation 1,125.25 ft Bottom of shelf elevation 1,131.50 ft Permanent pool elevation 1,132.00 ft SHWT elevation n/a ft Top of shelf elevation 1,132.50 ft Temporary pool elevation 1,134.00 ft Form SW401-Wet Detention Basin-Rev.4 Parts I. & II. Design Summary, Page 1 of 2 Permit No. (to be provided by DWQ) 1110MG NIINO ' 0 Volume and Surface Area Calculations SAIDA ratio 3.74 (unitless) Surface area at the bottom of shelf 7,875.00 ft2 Volume at the bottom of shelf 30,138.00 ft3 Permanent pool, surface area required 12,577.00 ftZ Permanent pool, surface area provided 12,727.00 ftZ OK Permanent pool volume 39,645.00 ft3 Average depth for SAIDA tables 3.12 ft OK Surface area at the top of shelf 11,645.00 ftZ Volume at the top of shelf 37,193.00 ft3 Forebay volume 8,432.00 ft3 Forebay % of permanent pool volume 21.27 % OK Temporary pool, surface area provided 17,331.00 -ft' Drawdown Calculations Treatment volume drawdown time 2.00 days Treatment volume discharge rate 0.11 ft3/s Pre-development 1-yr, 24-hr discharge 9.54 ft3/s Post-development 1-yr, 24-hr discharge 0.11 ft3/s Additional Information Diameter of orifice 2 in Design TSS removal 85 % Basin side slopes 3.00 :1 Vegetated shelf slope 10.00 :1 Vegetated shelf width 10.00 ft Length of flowpath to width ratio 3.00 :1 Length to width ratio 1.50 :1 Trash rack for overflow & orifice? y (Y or N) Freeboard provided 1.34 ft Vegetated filter provided? y (Y or N) Recorded drainage easement provided? n (Y or N) Capures all runoff at ultimate build-out? y (Y or N) Drain mechanism for maintenance or emergencies 8" gate valve OK OK OK OK OK OK OK OK OK OK OK Need a recorded drainage easement OK Form SW401-Wet Detention Basin-Rev.4 Parts I. & II. Design Summary, Page 2 of 2 BEFORE YOU DIGI SCALE; 1" = 50~ NC ONE CALL 50 0 50 NOTES: ~ 1. L IS LENGTH OF RIP l (TOLL FREE) RAP APRON. W IS THE • NCGS "BILBO" NAD 83 N~282808.871 M WIDTH OF THE RIP RAP ~ I ~ APRON. I E~413835.711M O REDUCED SCALE OF MAP MAY BE Combine Factor~0.9999303 f03 2. SEE PLAN FOR 1155 _ DIMENSIONS AND MATERIALS '~'i ~ ~ DUE TO METHODS OF REPRODUCTION. TO BE USED. I _ ~ PLAC PLACE RIP-RAP AROUND I , m PI PIPE AS DIRECTED BY 3. FlLLER FABRIC SHOULD I -~'s~t 1HE ENgNEER BE INSTALLED BETWEEN RIP ~`~i;~ / ~ ry / i / RAP AND SOIL FOUNDA110N. 1150 ~ ti.-11 ~ OR 1-800-632-4949) do 11~~ ~ 1'~~ ~ ~ S 86 32 2 E 141.43' - ' ~ ; 1\;% c A- i ~ - ~ 125 ~ X ~ , ~ 4 " " .74% . - 81'43 33 ~ X O1 E ~,`lll 1i1~: ,a Q E ~ N ~ ~ FEMCE 134 ~ ~ ~ - 4p8 ~ X . '8J ~ ~ w 1145 . -,1~--.._-, _ ~ N ~ ~ ~ ~ ~ _ , . , i ~ ~ g- , ~ t~ Z C o / ' X29 ~ 1.. ~ w_ _ -1 X60 ' ~ Mm H•I• ~ 1~1~=, EwsnNC t't~'"~ ~ ~ ~ ` - e~ ~ ~ / f a / z--- I i / f _ . s ~ 1140 GRADE -11t~ a ~ d i . i .1 ~t. C ;.,~.~~s ~ r ~ ~ f,,\SPRING BOX ~ , ~ ~ ~ Rn .t.y-~, ,1' tTf i - , . SEE NC DOT ~ ~ ~ H -6~ STD. 840.41 ~ / SLOPE ~ :`Vt~,. I_~ > ~ ~ /i;' - x`115 / ~ / / / ~ ~ (2.84 Acres / ~ d 1135 ,~~~ii- ~ i X11; t'i ~ ~ ~ ~p 14 1 - \ ~ \ ~r EXISTING ~ 'C { i , i ' /'I ~ ~ 1 ~ \ ~ ~ ~ \ / ' ~ ~ ~ E~. NCDOT R/N+ Dhk ' FlLTER BLANKET MIRAFl 500X FILTER FABRIC OR 18" CMP1y~~~ 1~1 SUBGRADE; ~ / / ` ~ / ~ ~ ~ \ ~ ~ , • F•no• Cann ~ ' ~ ~ \ / APPROVED EQUAL ~ 1~ Section a-A 1~ 30 t t. t t _ 4 h ~ ti 9 R•ba wt ~ v ~ :,`v ~ ` i \ ~ ~ 420 LF OF 18 CMP ~'S8 i + 1 ' ' , ~ TO BE INSTALLED IN ~ I 0.3 ~ ~ C RIP RAP APRON ? g T1 ~M ~1 / ~ EX .fie ~ \ ~1 ~ EXISTING STREAM BED ~ ~ ~ % INSTALL PIPE ' 11 ~ MIN 8" OF DETAIL INV. 0.3' B0.0W N0.57 STONE ~ ~ V' ~A / / 1~ + ~ ~ A~ ~ ~ ~ ~ / . SCALE: NOT TO SCALE C~1 ~0 1125 EXISTING gZADE ~ a f ` . 1 , ~ \ , ~ 1 ~ ~ \ \ ~ ` ; EXPANDED EXPANDED METAL (ALUMINUM OR l \ 1 A , A ~ ; ~ ~ ; NCDOT Pr ert ~ ~ ~ HOT-DIPPEI HOT-DIPPED GALVANIZED) GRATING TO CROSS SECTIQN A 722-588 ~ ~ ~ t ~ \ ~ ~ , ~ \ ~ / j EXTEND 1- ,A. ~ ~ , ~ ~ ~ CT N ~ ~ ~ CONNE -EXTEND 1-0" BELOW TOP OF SPILLWAY. HORIZONTAL SCALE.' 1 "'50' CONNECT WITH STAINLESS STEEL VERTICAL SCALE.' i ".'5' ~ ~ ~ \ ~ ~ , \ + ~ ~ HARDWARE \ , ~ ~ HARDWARE (OR APPROVED EQUAL) TRASH RACK SHALL BE CONSTRUCTED TO ALLOW ~ v A ~ / LOCKABLE HINGED ACCESS AND MAN PASSAGE TO v y. ~ v ~ ~ 't ~ o ~ / OPERATE/INSPECT. VALVES PERMANENT SEEDING SPECIFlCAl10NS , ~ 1. TOP OF RISER SEEDING MIXTURE I ~ ~ 7'-8" ~ Sacies Rate (ID/ocn) a setae Sericea kepedeza 100 11'5212 W 32,34 \ P , ~ \ ; + / ~ Koroan lespedeza 20 \ ~ I , ~ / / j N V j p~ ~ ~ • STANDARD VALVE STEM SHALL BE R~P~y ~ 15 ~ CONNECTED TO STRUCTURE Kmtuc bi race ~G. ~ ~ ! G~ ~ ~ ' ~ 11 + y ~ / _ MANHOLE STEPS I I MATH STAINLESS STEEL SEWING NOTE 5 ' ~ ~ S ~ A V " ~ \ \ ~ + \ ~ % 16 MAK. SPACING ) 5 / e~ Nanc York Pr ert ~ , ; / Y aP Y PROPERTY LINE SHALL ~ p5 I 11'~! l/ " I I A i ` ' After Au . 1 use unecarffled seed for serlcea lee za. BRACKETS (MIN. OF 6) g ~ P~ ~„V 833-278 ~ ` SERVE AS THE G ti ~ \ ~ , . ~ ~ ! 2 WATER I 1 I AND HARDWARE NURSE PW~TS n I Between May 1 and Aug. 15 add 10 ~/Acro Gemwn~t or 15 ~/Acn Sudongraee. Prbr sC J to May 1 a after Aag. 15, add 40 Ib Acro tye (groin). ft may M beneAcial to plant the ~ Z Z NEA DRAINAGE ~ ~ ~ ti \ + ~ DEU TED 5~ , i + fi, , , , V ~ ~4',, QUALITY ORIFICE BASIN, TYP. + I ~ , 1 , ~ , ,1 , . ~ 0 i ELEV. - 113200 I I grosses in bte summer and overeeed the lapedezae 1n Mach. / `I~ 1 II ~ ~ 1~ O `V I o ~ SEWING D11TES Acceptable ~ j,~ ~ O ~ O I 0 ^ Bebw 2500 ft.: Aug.15 to Sept. 1 Juy 25 to Sept. 15 ~ ~ 0 w ~ ~ I ~ I I + , 1 •~1 / T F NN I j . , , , ~ B00 TYPE LEXIBLE CO EC110N ~ I I Mar. 1 to Apr. 1 .Mar. 1 to May 10 O r ` V I i i ~ ~ + ( USE STAINLESS STEEL HARDWARE , _ m / 1..- AND COMPLY WITH ASTM`C923 _ ~ I POP + 1 1 ~G+I.A 1 RIP-RAP ~ " (4.86 Acres) o DRAINAGE , ~ , 8" GATE VALVE SERIES Above 2500 ft: day 25 to Aug. 15 _ Jay-15 to Aug. 30 V ~ 2500, 250 PSI RESILIENT Mar. 20 to Apr. 20 Mar. 5 to May 15 ~ ~ I , , O N 0 ( ` , \ \ , 1 OUTLET PROTEC110N " ~ ~ . , + EASEMENT ~ + , ~ , ~ YY~8.5 I I '~1' Complete eeedtng earlier to fall, and start later in spring an north and east facing ek>pes. tY WL I WEDGE GATE VALVE (OR °"'"`~~I'•'~ SOIL AMENDMENTS Q~ O (W'; ~,I,1) Donna Huffman Pr ert ~ BOUNDARY ~ ~ + ~ Qo ~5 DOWEL BAR MIN. OF 12 ~ Y i . t 1 ~ + ' ,=j- ~ , ~ ' L 12 EVENLY SPACED TO INSURE h I I APPROVED EQUAL) follow recommendatkne of eon testa or appy 4,000 Ib/Acn ground agricultural Ameetone ~y 2 722-315 ~ ~ I • , ~ 8" I , ,°,T~2 CONNECTION TO f , ~ ; " ~ _ VALVE SHALL BE and 1000 Ib/Acn 5-10-10 }ertill:er. "V O CONNECTED TO MULCH v , ; ' / ~ + , do~18 O ANT FLOTATION FOUNDA710N I STRUCTURE WITH ,A~p~ 4,000-5,000 Ib/Acro grain straw or equMalent cover of another euttabk mukhfnq materkl. . I....... 4` +,1 + , ' ~ 'SEE DETAIL 1 C.t.d (OR APPROVED EQUAL) ~ STAINLESS STEEL " method on c till ~o a'kinq with aephaft, roving, or netting. Netting b the pMemed anchorin 2 ~y 5/8 SQUARE ALUMINUM BAR P Pe g ~ ~ ~L ARDWARE MAX. 6" SPACING BETWEEN BARS MNNTENAJ~CE W O W . . ' ~ ~ i EMERGENCY' . ~ ; I t ~ Z / y / ~ ~ . _ - ~ SPILLWAY` ~1 1~,,+'' o, / I ~ I ~ I ~ Mow no moro than once a year. Refertllize In the second yea unless growth h faly adequate. V ~ J Reseed, refertiAze and mulch damaged anon innnedtatdy. _ 3TORMWATER POND l \ ~CLAS,S A~ t, ~ UNNAMED ALUMINUM SHOP FABRICATED ~ ~ S~~q~`n~ V W CONSTRUCTION ~ / ~ 1,, , - I BASIN TO BE 3:1 , ~ RIPR ,1 i " ~ SEE DETAIL 4 C.10 ; • , , ; ~ , ;1 + + TRIBUTARY OF i MIN, 6 X57 WASHED STONE ON SIDE SLOPES ABOVE / , OUTLET TRASH RACK (OR APPROVED SEWING MIXTURE ~ Y S E U EN C E ~ ~ d . - I , 1, CUB CREEK / i 4 d< BELOW VEG. SHELF! / ~ ~ ~ ~ • + ~ / / ~ WOVEN STABILIZATION FABRIC STRUCTURE EQUAL) CONNECT TO CONCRETE Species Rate {Ib/A~cn) ~ 3 1 OBTAIN PLAN APPROVAL AND ALL ~ 0 ~ ~ " ~ ' 1 + i O FOREBAY TO BE 3 ~ ~ ~1, ; ~ / i , SHALL BE STRUCTURE MATH STAINLESS STEEL Rye (yrnln) 120 ANCHORED TO HARDWARE Mnual IeepedeZa (Kobe to Piedmont and ~ O q~ APPLICABLE PERMITS. FT IN DEPTH WITH ~ ~ ~ 1, r / CONCRETE Coastal Pialn, Korean In Mountaim) 50 (2) CLEAR SITE, BUT DO NOT GRUB MAX 2:1 SIDE SLOPES / ~ ~ ~ ~ ~ ' . ~ 1 I 1 CI~! , ~ ' I ANTI-FLOTATION Omit annual lespede:a when duroHorl of temporary cover is not to eztend beyond June. FOUNDATION TRASH RACK s®INC DATES ~ (3) INSTALL ALL EROSION AND SEDIMENT ~ ~ ~ { ~ VEGETATIVE 6'-0" CONTROL MEASURES, k .f' / 1 ti i ~ ~ I , + + / FILIER STRIP COMPACTED SUBGRADE SHALL BE Mountains -Above 2300 ft: Feb. 15 to May 15 (4} GRUB SITE. Z I f 0 ~ ~ ~ ` ~ i ' 1 - I MINIMUM OF 95% STANDARD PROCTOR I. / SIDE Below 250D ft: Fib. 1 to May 1 Piedmont - Jan. 1 to May 1 (5) CONSTRUCT STORM WATER POND AS / , ~ 1 \ . ' I ~ _ SEDIMENT BASIN. m ~ - , , . ~ CLASS B RIP RAP MAXIMUM DRY DENSITY (ASTM D-698) Coastal Plain - Dec. 1 to Apr. 15 ~ ~ ~ I E OUTLET PROTECTION I 6 COMMENCE ROUGH GRADING OF 1HE SITE. ¢y, ~ ~ ~ SOIL AMENDMENTS Follow recommendations of Boil tests or appy 2,000 Ib/Acn ground agricultural Ameetone (7) INSTALL STORMWATER MANAGEMENT ~ ~ ~ti f 'h 11@ LF ~ ~ , L¦5' ' , ~ , 15 RCP ~ . , , " and 750 Ib/Acro 10-10-10 ferftlizer. 00 MULCH W O DEVICES. ~ FOREBAY B RM ~ ~ % ~t , { , . . , r,, ~r , , T 1a RI R A M Y T L DE A L (8) ROUGH GRADE THE SITE. > EL. 1133 ~ ~ ' . ' ~ • Apply 4,000 Ib/Acro straw. Mchor straw by tacking with oephaR, netting, a o mulch Q (9) SCARIFY, SEED, FERTILIZE AND MULCH ALL w (CLASS GRIP-RAP) ~ , STRU±~IURE ' ' SEE DET anchoring tool. A dick with blada set Healy straight can be aced as a muk:h anchoring tool. Q MNNTENANCE \ ~ ~ ' _ \ AIL 1/C.1.0 DISTURBED AREAS, SEE DETAIL 4 C.1.0 ' _ . ! Refertllize K rowth is not fuly adequate. Reseed, nfert~izs and mrdch immediatey folbwing erosion or other damage. (10) AFTER DISTURBED AREAS ARE STA ~ . ~ 10 Fr' VEGETATED Sf~ j C , i,~;' i WITH VEGETATION, THE CONTRACTOR SHALL I ; ~ o ALL , oN ALL SIDES OF MAIN , 1 ~ \ SCALE: NOT TO SCALE C,~,O RETURN TO THE SITE AND REM VE r. .0 ~ w , ~ POND (10:1 SLOPE) I I`„_/, ~ ~ TEMPORARY EROSION CONTROL MEASURES ~ . \ T A IN N ` SEE DETAIL 8 CJ.O I I / a ~ ~ AND REMOVE SEDIMEN FROM B S / R STORE 0 ~ / i ' ` REPAIR EROSION FEATURES AND E y , •y ~ i , , , • f 9 f j~. , ~ SOIL TRIANGLE OF THE BASIC TEXTURAL DETAIL ~ 0 VEGETATIVE SHELF. CONTRACTOR SHALL ~.~'S , I , i i, ~ ~ ~ 8~ CLASSES, FROM PRINCE GEORGES CO, 1993 SCALE: NOT TO SCALE C,1,0 W V ASSURE THAT BASIN IS RESTORED TO THE w - DEPRESS 9ERM EL i! ! EMBANKMENT d• ~ , ORIGINAL DESIGN CONFIGURATION AND J U.S.D.A. TEXTURAL TRIANGLE o ~ . ~ TO 1132 FOR FLOW ~ TOP DAM ELEV: 1135,50 ELEVATIONS. d ' ENTRANCE j~~ 100 3 CLAY wa~aaaaaittu~waolsaNdsaNru~ 0 ~ ~ , ~PEgES PLANTING PATTERN PLANTING DATES ~ -TOP OF DAM ; ~ M SPILLWAY ELEV: 1134.50 1.36 FREEBOARD 100 YR FLOOD ELEV: 1134.14 ELEV. 1134.14 ~ ~.n~nb ~larA-aN3a " a H s ~ , 4 O.C. March-June 0 %i Leerala oryzoidea 2 , PIA 1~G SOIL GUIDELINES: " March-June 3 ~I . ~ II TRASH RACK Juncue effueua 24 O.C. , 9 ~ » _ ro w ~ O- 3:1 SIDE - ~ I i, 4 3 (SEE DETAIL) ~QQ~ ~ ~bW - 50FT TEXTURE AND STRUCTURE - ~ ^ 90 10 PLANTING SOILS FOR BIORETENTION ~ Juncua coriaceua 24 O.C. March June 99 SLOPE MAX - RISER ELEV: 1134.00 Scirpua valldue 24" O.C. March-June ~ 's?• _ - - I ~ 1 48"X48" - - - - - - - - - - - - - - - - - ELEV_i134_00 AREA SHALT HAVE A SANDY LOAM, PROPOStD - - -I+ _ _ _ _ _ _ _10 YR STORM ELEV: 1133.62 I_ELEV: 1133.62_ 2 'uj 4 LOAMY SAND, OR LOAM TEXTURE. 1) PLANT SPACING FOR SPECIES LISTED IS TO BE RANDOM MAINTANENCE - CONCRETE RISER - - - - - - - - - - - -I {NATURALISTIC), ANO NOT IN A REGULAR GRID PATTERN. ON-CENTER 2 Robert E. Aehle Pr ert ~ ACCESS POINT - - - (SEE DETA?L) FOREBAY BERM: 1133.0 80 20 `~a CLAY CONTENT RANGING FROM 10x SHEET N0. 1 ~ TO 25Y0. Y oP Y SPAgNG IS TO BE AN AVERAGE SPAgNG DIMENSION. 720-537 ;h~' - WATER QUALITY ELEV: 1132.0 `/PERMANENT POOL tMANENT POOL p - INFlLTRATION RATE OF SOIL SHALL 2)POST INSTALLATION CARE: THE PLANTING SHALL HAVE A MINIMUM .~8 101'x88' 101'x88' SEDIMENT REMOVAL 70 a"Y 30 BE GREATER THAN 0.5 IN/HR. C.' ~ O ELEV: 1131.0 ~ -SOIL ACIDITY -SOIL pH SHOULD LIE TWO YEAR WARRANTY PERIOD FOR PUNT SURVIVAL/REPLACEMENT. AT ,~9 THE END OF THE FIRST YEAR AND AGAIN AT THE END OF THE TWO ~g ~<v 2 BETWEEN 5.5 AND 6.5. YEAR WARRANTY PERIOD, ALL PLANTS THAT DO NOT SURVIVE MUST BE 0 ~ 2 FOREBAY BOTTOM: 1130.0 60 40 ~ -SOIL SHALL BE OF UNIFORM S COMPOSITION, FREE OF STONES, REPLACED. 9 ~ o PERMANENTS IM T ST t , 5 ,c ED EN ORAGE 125 2 '125.25 STUMPS, ROOTS, OR ANY OTHER 0 ~ p ~ OUTLET LEV: 1123,15 110 LF 15" RCP PRINCIPAL SPILLWAY BARREL ~ 1,0% ~ BOTTOM ELEV:' 1124:25' ' NTLNG NOTES A TATIVE SHE VG 5' ' 50 50 MATERIAL OR SUBSTANCE WHICH q ~ W ~ MAY BE HARMFUL TO PLANT N ~ 4J ~ ~ A w GROWTH. 2 INV ELEV: 1124.25 -SOIL SHALL BE FREE OF PLANTS OR d' ~ Q 3 ~ Vv 40 air s~TM 60 PLANT PARTS OF BERMUDA GRASS, , , ~ ~ RIP RAP OUTLET 4'X4'X8" -CONCRETE ~ QUACK GRASS, JOHNSON GRASS, _ SCALE: NOT TO SCALE C.1.0 ~ PROTECTION DRAIN DIAPHRAGM ~ ~av+ MUGWORT, NUTSEDGE, POISON IVY, U ~ V~ 30 sµar 70 CANADIAN THISTLE, OR OTHERS AS Q ~ O~ DRAIN FILTER STORMWATER BASIN DESIGN TABLE NOTES: ~ SPECIFIED. ~ WETBASIN M IN NANCE 1. ACCUMULATED SEDIMENT SHALL BE REMOVED AT THE END OF COMSTRUC110N. SPILLWAY SPILLWAY SA SA VOLUME VOLUME VOLUME Q~ ~ LUJ 2 Y REMOVED SEDIMENT SHALL BE DEPOSITED IN A SUITABLE AREA. POND MUST BE WIDTH SIDE SLOP READ, PROVIDED. READ. SCHE ~ STABILIZED WITHIN 14 DAYS AFTER THE COMPLETION OF CONSTRUCTION. D. READ. PROVIDED 20 80 SOIL TESTING Iii ~ ~ U J ~ou~r -PRIOR TO INSTALLATION, TESTING Q ~ W _ V TASK SCHEDULE NCGS "ROSCOE" NAD 83 2. THE CUT AND FILL SLOPES SHALL BE 3H:1V OR FLATTER. 10' 3:1 12,577 SF 12,727 SF 24,100 CF SF 24,100 CF 30,785 CF ~n nn MUST BE PFRFORMF~ TO FNSIIRF ~ 4 Q V ~ u-nc~eea etn~ 3. PROVIDE DRAIN TO COMPLETELY EMPTY BASIN FOR MAINTENANCE. 4. RISER SHALL HAVE TRASH RACK ANTI-FLOTATION AND ANA-VORTEX DEVICES. LOAM LOAM SLT THE SOIL MEETS THE FOLLOWING Combine Factor-0.9999297 6. NO TREES, SHRUBS AND VEGETATIVE PLANTS TO BE PLANTED ON DAM EMBANKMENT. TOTAL 114'x171' Y CRITERIA: UNING ANNUAL _FOREBAY 114'x48' sAno - pH 100% 90 SO 70 60 50 40 30 20 10 100% ORGANIC 5.5 - s.5 BASIN 114'x23' RGANIC MATTER: 1.5 RENEWAL ANNUAL STORMWAMR POND DETAIL SAND SILT - 3.0% PERCENT SAND MAGNESIUM (MG): 35 Fir LANT AS NEEDED SM Elev. 1154.33' LBS/ACRE ? i t ACEMENT DETAIL r4 PLANTING SOIL SPECIFICATIONS PHOSPHORUS (P209): i 03iia q REMOVAL EVERY 3 YEARS SITE PLAN I 100 LBS/ACRE SOLUBLE SALTS: NOT DETAIL LREMOVEE REMOVAL WEEKLY E~413264,472M 5. DRAINAGE PIPE BARREL SHALL BE RCP PIPE ONLY BASIN DIMENSIONS: OR R AS NEEDED DU ING SCALE: NOT TO SCALE C. 1.~ SEDIMENT M H R N A TO EXCEED 500 PPM P'. •`Y SCALE.• 1 ".'50' ER MOWING A S NEEDED SCALE: NOT TO SCALE V-1 .