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Home My WebLink AboutSW6080602_Stormwater Report_20240730 O • • civilconsultants • • LAND DEVELOPMENT CONSULTANTS STORMWATER IMPACT STATEMENT PROJECT GAIN June 10, 2024 Project # 31004 `,,•,•••4\A C ARO% Q, aFess��ti, ` S. SEAL I ! 3 I IV Pi '',1j11141 NN% w110/24 Prepared For: CRB ARCHITECTS-ENGINEERS 701 Emerson Road SUITE 500 ST. LOUIS, MO 63141 LAND PLANNERS + CIVIL ENGINEERS 3708 LYCKAN PARKWAY, SUITE 201 DURHAM, NC 27707, PHONE:919.490.1645 WWW.CIVIL-CONSULTANTS.COM LIC.C-1030 Stormwater Impact Statement Purpose The purpose of this report is to assess stormwater impacts associated with proposed construction of a parking lot and building expansion in Robeson County. The site has existing stormwater permits associated with the site. This project will be a modification to existing permit SW6080602. The property falls within the NCDEQ Fayetteville Regional Office's jurisdiction but stormwater is reviewed by the Raleigh Regional Office. This analysis addresses requirements prescribed in the State's regulations related to stormwater runoff control. Existing Site Conditions and Drainage Characteristics The subject property is located at 2120 NC-71 in Maxton,NC. The site is developed with industrial buildings and supporting infrastructure. Runoff leaves the property in three locations, at the north west property line through a 24" culvert pipe, to the east via an existing drainage canal, and to the south west property line to the Lumber River. Impervious Surface Area The east side of the project will add 118,373 SF of new impervious on site. These areas are associated with the parking lot expansion. All new impervious areas will drain a proposed wet pond for treatment. The west side of the project will add 100,574 SF of new impervious on site. These areas are associated with the building addition and truck dock. The building addition will be in existing drainage area B and drain to drainage area A to reorganize drainage areas from existing stormwater permit SW6080602. Applicability of Local Stormwater Regulations The relevant performance requirements for this site are: High density projects SCMs shall be designed, constructed, and maintained so that the project achieves either "runoff treatment" or "runoff volume match" per 15A NCAC 02H .1003. Stormwater outlets shall be designed so that they do not cause erosion downslope of the discharge point during the peak flow from the 10-year storm event as shown by engineering calculations. 2 TSS Removal Runoff from proposed site development will be managed by two on-site wet ponds. These ponds have been designed per the MDC stormwater design criteria and will be used to satisfy water quality requirement. 1-Year Volume Management Stormwater runoff will be managed utilizing the on site wet ponds. The ponds will catch a portion of the drainage area limiting the outgoing runoff from the increased impervious. The analysis of the stormwater device was performed using Hydraflow Hydrographs with Autodesk Civil 3D. This software is accepted by industry standards. The point of interest (POI)was modeled in the pre and post conditions for the 1-, 2-, and 10-year storm events. Peak Runoff Rate From a stormwater runoff mitigation perspective, the wet ponds will slow down runoff rates, which inherently provides reductions in runoff quantity and peak runoff rate. Allowing for the effective drainage area mitigation, the Qi value will not significantly change between the Baseline Date and Post-Development conditions. West Side Drainage Basin Summary Storm Events (cfs) Site Condition 1 Year 2 Year 10 Year Pre Development 4.76 7.35 15.57 Post Development 0.06 0.07 3.14 East Side Drainage Basin Summary Storm Events (cfs) Site Condition 1 Year 2 Year 10 Year Pre Development 4.34 6.94 15.34 Post Development 0.05 0.20 6.03 Conclusion: Based on the information contained herein, proposed site improvements for the subject project will meet State regulations and policies applicable to management of stormwater runoff quantity and quality from the subject property. End 3 .11r ..Li. 013 4 + rY. Jr /3 % Jr �, r— /( Jr J Air rl► A/ rlr +I. S h. r .. rr rlr rlr T.4 R, / G t�� irrrar'S alr •Jr 4. 4. . ,= r __ /3 �, y 46 ,� Florali ,M. 4i 4 .1r1 College PROJECT w - LOCATION t 0. -_ -- Q�� — ._r_-.J otAi� - . I ..16. 4. -Si / . /— — ....../ ... ..... t. = __ -41111111111r0 .k ., ' -A— I -DipARl0 1- Hydrologic Soil Group—Robeson County,North Carolina,and Scotland County, North Carolina o N n 651100 651500 651900 652300 652700 653100 653500 653900 654300 654700 655100 655500 34°46'53"N 1 lim_8 34°46'53"N 1 ,,. -.- KanA - P�oB Mc g _ KB NsC P ("oA WS �� rW NA cA WkB 17.1106„:1 WkB L � R a PeA \r � A, w' GA aAKB ,iq VaA ‘W� Co RuA o Lb • t. , NC 11-M 1aB % R 111 Ba ts *410 N KnBAnBJoA%.›.1L�ruOsAo. Kly ( * '& WaB JoA e M Pip 'KnAoBPm MD FaB at.,..., .1%1' LuA g1 70 ,WkB II IA OCIAIP W 8 PrE3 .o011k . e Pmip • • . LaB Pm nLi`�3 WaB Lu,lit A cfrif 34°45'19"N 34°45'19"N 651500 651900 652300 652700 653100 653500 653900 654300 654700 655100 655J00 3 3 Map Scale:1:20,600 if printed on A landscape(11"x 8.5")sheet. Pi Meters N 0 300 600 1200 1800 Feet 0 1000 2000 4000 6000 Map projection:Web Mercator Comer coordinates:WCS84 Edge tics:UTM Zone 17N WGS84 USDA Natural Resources Web Soil Survey 2/7/2024 00. Conservation Service National Cooperative Soil Survey Page 1 of 5 1900000 FEET 1910000 FEET 380000 FEET 79°19.30"W 79°19'0'W 79°18'30"W 79°16'0'W 380000 FEET �' ,, .... ‘,,,,i.,i.i iii:.5...;:t:i.i a e ,� 34°4730 N L y.(,�k''','.nu :. .''''.;t1,1'7...' .,',. .1.11,‘•,. q ,iii:- 34°47'30"N it 1. • ',. • 0 e • af: �, .. = - • r • 34°470'N �� p1\ / C 4; i 34 47 a N Sc: � < `o, r tehOOS 9 �''I I oNIVCOR°0 0 /S �' ,'.. , I'rao )3 ° •✓� Mg i • •- 0.,I ,rCi---- 404.4,i, ', ,:f:•' • `v_ 1 . °, �1 11 r..lico, , F'°" • 34"46'30"N c +1 - �_ i�� ,�1 �`N iY 1544 ``{" •t.- .L 34"46'30"N } 40 .... , ..„,..,. . \ . \,‘ , • . [ 4 b4t•V 7. , , „,.• .: .„...N, ... \SI ` '''',..4 .- • \- \ , P #" . .\\. ...„.'r$•:,••, k • J y \ 111 ' /� _ ,� \\ � r" :::,, {�� ZONE ACE O +'t '.•`• \1 .s ��MA3 J�/ it •.. ) a y� . `4 4 -4 liA'—',... ir:IIII.':lriii -...' 1I 11 1111111 y` \] i _ plea ./. _,- , . '',....,9/, - 34°48'0'N a A' � �.^ ! �, ',. 34.46.0"N 370000 FEET 370000 FEET 79°19'307/ 79.10.01N 79°1030"W 79°18'0"W 1900000 FEET 1910000 FEET g,rxrr ... ..1, „crating Technical State This digital Flood Insurance Rate Map(FIRM)was produced through a unique cooperative partnership between the State of North Carolina and the Federal Emergency Management Agency(FEMA). The State of North Carolina has Implemented a long term approach to fbodplain management to decrease the costs associated with flooding.This is demonstrated by the State's commitment to map flood hazard areas et the local level.Asa part of this effort,the State of North Carolina has joined in a Cooperating Technical State agreement with FEMA to produce and maintain this digital FIRM. FLOOD HAZARD INFORMATION NOTES TO USERS SCALE NORTH CAROLINA FLOODPLAIN MAPPING PROGRAM SEE FIS REPORT FOR ZONE DESCRIPTIONS AND INDEX MAP For information and questions about this map,available products associated with this FIRM including Map Projection: E NATIONAL FLOOD INSURANCE PROGRAM historic versions of this FIRM,how to order products or the National Flood Insurance Program in general, THE INFORMATION DEPICTED ON THIS MAP AND SUPPORTING North Carolina State Plane Projection Feet(Zone 3200) 'OOD INSURANCE RATE MAP please call the FEMA Map Information eXchange at 1-677-FEMA-MAP(1-877336-2627)or visit the FEMA Map DOCUMENTATION ARE ALSO AVAILABLE IN DIGITAL FORMAT AT ServiceCenterwebsiteathttps://msc.fema.gov.An accompanying Flood Insurance Study report,teas of Map Datum:NAD1983(Horizontal),NAVD1988(Vertical) Revision(LOMR)or Letter of Map Amendment(LOMA)revising portions of this panel,and digital versions of this HTTP://FRIS.NC.GOV/FRIS FIRMmaybe available.AMapsirviceCnter. lineFloodplainMappingProgramwebsitaalMlp:rwww.neoodmaps.com, a 0.0 NORTH CAROLII I oe4"`�nTea OIRM ma me FEMA Map isit tit a orth C. l inch=500 feet 1:6,000 O , p Without Base Flood Elevation(BFE) Communities annexing land on adjacent FIRM panels must obtain a current copy of the adjacent panel as well as 0 250 500 1,000 L T Zone'A,V,A99 the current FIRM Index.These may be ordered directly from the Map Service Center at the number listed above. PANEL 9307 With BFE or Depth Zone AE,AG,AH,VE,AR Feet r—, ¢F,Np sly For community and countywide map dates refer to the Flood Insurance Study report for this jurisdiction. Meters W SPECIAL FLOOD .. f,: Regulatory FloodwayTo determine if flood insurance is available in the community,contact your Insurance agent or call the National 0 75 150 300 r` U FEMA 0"HAZARD AREAS Flood Insurance Program at 1-800-638-6620. IW� 0.2%Annual Chance Flood Hazard,Areas Flood Insurance Study(FIS)means an examination,evaluation,and determination of flood hazards,corresponding PANEL LOCATOR water surface elevations,good hazard risk zones,and other flood data in a community issued by the North Carolina es ,,, co ,el Contains: of 1%Annual Chance Flood with Average Floodplain Mapping Program(NCFMP).The Flood Insurance Study(FIS)is comprised of the following products Depth Less Than One Foot or With Drainage used ogether:the Digital ranee HazaN Database,the Water Surtace Elevation Rasters,the tligitally de ved, ? P g auegenerated Floodlnsurance Rate Mapandthe Floodlnsurance Survey Report.AFloodlnsurance Survey isa COMMUNITY CID PANEL SUFFIX Areas of Less Than One Square Mile Zone X ompilation and pnesen orlon of flood risk tla a for specific watercourses,lakes,and oas al flootl hazard areas within '41 943 49,03 ROBESON COUNTY munity.This report contains detailed flood elevation data,data tables and FIRM indices.When a flood study is 370316 9307 M Future Conditions 1%Annual completed for the NFIP,the digital informatlon,reports and maps are assembled into anFlS.Information shown on i 946294a�8294920002�,12 aO'L� SCOTLANDCOUNTy 370316 9307 M this FIRM is provided in digital format by the NCFMP.Base map information shown on this FIRM was provided in Hoke L ` Cumberland Chance Flood Hazard Zone X digital format by the NCFMP.The source of this information can be determined from the matadotaacallablaln the 9451 9431 9491 0401 041 421 digital FLOOD database and in the Technical Support Data Notebook(TSDN). 94fi0 OTHER AREAS OF9440450 94809490'400,d0ii20 „ Area with Reduced Flood Risk due to Levee /y _—____—__ FLOOD HAZARD ACCREDITED LEVEE NOTES TO USERS:If an accredited levee note appears on this panel check with your local 8 99�/ O See Notes Zone X community to obtain more information,such as the estimated level of protection provided(which may exceed the 9308 9328 9348 9388 9388 0308 03�i6 OTHER 1-percent-annual-chance level)and Emergency Action Ran,on the levee system(s)shown as providing protection. Scotland even O Areas Determined to be Outside the To mitigate flood risk in residual risk areas,property owners and residents are encouraged to consider flood \ AREASinsurance and flootlproofing or other protective measures.For more information on flood insurance,interested 8397 931] 9387 9397 Robeson 0.2%Annual Chance Floodplain Zone X parties should visit the FEMA Website at hdps//www fema gov/nabonakflood-insurance-program, 9326 9346 9366 0326 0346 639693089318 93869398 ' II Channel,Culvert,or Storm Sewer PROVISIONALLY ACCREDITED LEVEE NOTES TO USERS:If a Provisionally Accredited Levee(PAL)note 930593159325egoseo459355 938593es Accredited or Provisionall Accredited appears on this panel,check with your localcommunitytoobtainmoreinfornation,suchastheestimatedlevelof 8364 8384 9364 0304 0324 p34- y protection provided(which may exceed the 1-percent-annual-chance level)and Emergency Action Plan,on the 930493149324933493449354 93849394 ` Levee,Dike,or Floodwall levee system(s)shown as providing protection.To maintain accreditation,the levee owner or community Is GENERAL 9303 93130323 9333 934393539363 9373 9383 9393 0303 0313 ft required to submit the data and documentation necessary to comply with Section 65.10 of the NFIP regulations. tithe community does not de the necessary data and documentation or if the data and documentation 832 8382 0322 0342; STRUCTURES t t t t t t t t t t t t t Non-accredited Levee,Dike,or Floodwall or owner provide ry 930293129322 93329342935293629372 93829392 0302 0312, flen 0 provided indicates the levee system does not comply with Section 65.10 requirements,FEMA will revise the flood BM5510 x North Carolina Geodetic Survey bench mark hazard and risk information for this area to reflect de-accreditation of the levee system.To mitigate flood risk in 932193319341935 936193719381939103010311 '/ }� residual risk areas,properly owners and residents are encouraged to consider flood insurance and floodprooflng 83 8380 9300 0320 0340 BM5510 or other protective measures.For more information on flood insurance,interested parties should visit the FEMA 9320 9330 9340 9350-9360 9370 9380 9390 0300 0310 f MS ® National Geodetic Survey bench mark Website at hops://www.fema.gov/national-flood-insurance-program. BM55100201 02190229 0239 5( Contractor Est.NCFMP Surveybench mark 82 9208 9228 9248 92fi8 9288 0248 ® LIMIT OF MODERATE WAVE ACTION NOTES TO USERS:For some coastal flooding zones the AE Zone g` 0208 0.218)0228023B( 01 a-2—Cross Sections with 1%Annual Chance category has been divided bye Limit of Moderate Wave Action(LIMWA),The LIMWA represents the approximate \ ) landward limit of the 1.5-foot breaking wave.The effects of wave hazards between the VE Zone and the LIMWA 9267 9277 0207 0217 0227 0237 Water Surface Elevation(BEE) (or between the shoreline and the LiMWA for areas where SE Zones are not identified)will be similar to,but less 9 20 9226 9246 9286 0246 severe than those In the VE Zone. 92669276 0206 0216 0226 03.361, as Coastal Transect 9204 ,rtt o215—T Limit of Moderate Wave Action(LiM WA) az4 seed seta 92sa 0224 VERSION NUMBER ------- Coastal Transect Baseline 020 14 —- Profile Baseline g222 g2 ,a/Laad263 a 2UMBER 34 .3.3.2 2 9262 �� ^`ma \\ g2s2 g_t cmwmnns ale MAP NUMBER Hydrographic Feature I924692619271928f9291 1 > 3710930700M 926092)i 28U OTHER Limit Of Study 9179� p ":/?� MAP REVISED FEATURES Jurisdiction Boundary @9w`.,w•' December 06,2019 Hydrologic Soil Group—Robeson County, North Carolina,and Scotland County, North Carolina MAP LEGEND MAP INFORMATION Area of Interest(AOI) p c The soil surveys that comprise your AOI were mapped at scales Area of Interest(AOI) ▪ C/D ranging from 1:12,000 to 1:20,000. Soils Please rely on the bar scale on each map sheet for map Soil Rating Polygons • D measurements. 0 A p Not rated or not available Source of Map: Natural Resources Conservation Service n A/D Water Features Web Soil Survey URL: Streams and Canals Coordinate System: Web Mercator(EPSG:3857) B Maps from the Web Soil Survey are based on the Web Mercator Transportation 0 B/D projection,which preserves direction and shape but distorts Rails distance and area.A projection that preserves area,such as the n C •.i Interstate Highways Albers equal-area conic projection,should be used if more accurate calculations of distance or area are required.C/D US Routes This product is generated from the USDA-NRCS certified data as 0 D Major Roads of the version date(s)listed below. n Not rated or not available Local Roads Soil Survey Area: Robeson County, North Carolina Soil Rating Lines Background Survey Area Data: Version 22,Sep 13,2023 A • Aerial Photography Soil Survey Area: Scotland County,North Carolina • A/D Survey Area Data: Version 31,Sep 13,2023 •v B Your area of interest(AOI)includes more than one soil survey area.These survey areas may have been mapped at different B/D scales,with a different land use in mind,at different times,or at • • c different levels of detail.This may result in map unit symbols,soil properties,and interpretations that do not completely agree • • C/D across soil survey area boundaries. • • D Soil map units are labeled(as space allows)for map scales • • Not rated or not available 1:50,000 or larger. Soil Rating Points Date(s)aerial images were photographed: Apr 17,2022—May O A 20,2022 O A/D The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background ▪ B imagery displayed on these maps.As a result,some minor shifting of map unit boundaries may be evident. • B/D USDA Natural Resources Web Soil Survey 2/7/2024 Conservation Service National Cooperative Soil Survey Page 2 of 5 Hydrologic Soil Group-Robeson County, North Carolina,and Scotland County, North Carolina Hydrologic Soil Group LIME1.1 Map unit name Rating Acres in AOI Percent of AOI BB Bibb soils A/D 214.0 13.3% Co Coxville loam C/D 5.4 0.3% FaB Faceville fine sandy B 0.2 0.0% loam,2 to 6 percent slopes GoA Goldsboro loamy sand, B 4.9 0.3% 0 to 2 percent slopes, Southern Coastal Plain Jo Johns sandy loam C 164.8 10.2% KaA Kalmia loamy sand,0 to B 118.6 7.4% 2 percent slopes LaB Lakeland sand,0 to 6 A 91.1 5.7% percent slopes Lu Lumbee sandy loam B/D 212.0 13.2% Ly Lynchburg sandy loam, B/D 2.9 0.2% 0 to 2 percent slopes MaA Marlboro sandy loam,0 B 18.2 1.1% to 2 percent slopes Mc McColl loam D 26.7 1.7% NoA Norfolk loamy sand,0 to A 82.7 5.1% 2 percent slopes NsC Norfolk and Faceville A 14.3 0.9% soils,6 to 10 percent slopes Pa Pactolus loamy sand A 9.1 0.6% Pm Plummer and Osier soils ND 33.2 2.1% PoB Pocalla loamy sand,0 to A 38.3 2.4% 3 percent slopes Pt Portsmouth loam B/D 166.5 10.3% Ra Rains sandy loam,0 to ND 2.5 0.2% 2 percent slopes W Water 21.2 1.3% WaB Wagram loamy sand,0 A 31.5 2.0% to 6 percent slopes WkB Wakulla sand,0 to 6 A 167.0 10.4% percent slopes Subtotals for Soil Survey Area 1,425.3 88.4% Totals for Area of Interest 1,611.6 100.0% USDA Natural Resources Web Soil Survey 2/7/2024 001. Conservation Service National Cooperative Soil Survey Page 3 of 5 Hydrologic Soil Group—Robeson County, North Carolina,and Scotland County, North Carolina Map unit symbol Map unit name Rating Acres in AOI Percent of AOI JoA Johns fine sandy loam, C 39.4 2.4% 0 to 2 percent slopes, rarely flooded KaA Kalmia loamy sand,0 to B 19.3 1.2% 2 percent slopes KnB Kenansville loamy sand, A 25.1 1.6% moderately wet,0 to 4 percent slopes LuA Lumbee sandy loam,0 B/D 23.2 1.4% to 2 percent slopes, rarely flooded MxA Maxton loamy sand,0 to B 25.1 1.6% 2 percent slopes OsA Osier loamy sand,0 to 2 A/D 4.2 0.3% percent slopes,rarely flooded PcA Pamlico and Johnston A/D 45.8 2.8% soils,0 to 1 percent slopes,frequently flooded RuA Rutlege loamy sand,0 A/D 3.0 0.2% to 2 percent slopes, rarely flooded Ud Udorthents,borrow pits B 1.0 0.1% Subtotals for Soil Survey Area 186.2 11.6% Totals for Area of Interest 1,611.6 100.0% USDA Natural Resources Web Soil Survey 2/7/2024 Conservation Service National Cooperative Soil Survey Page 4 of 5 Hydrologic Soil Group—Robeson County, North Carolina,and Scotland County, North Carolina Description Hydrologic soil groups are based on estimates of runoff potential. Soils are assigned to one of four groups according to the rate of water infiltration when the soils are not protected by vegetation, are thoroughly wet, and receive precipitation from long-duration storms. The soils in the United States are assigned to four groups (A, B, C, and D) and three dual classes (A/D, B/D, and C/D). The groups are defined as follows: Group A. Soils having a high infiltration rate (low runoff potential)when thoroughly wet. These consist mainly of deep, well drained to excessively drained sands or gravelly sands. These soils have a high rate of water transmission. Group B. Soils having a moderate infiltration rate when thoroughly wet. These consist chiefly of moderately deep or deep, moderately well drained or well drained soils that have moderately fine texture to moderately coarse texture. These soils have a moderate rate of water transmission. Group C. Soils having a slow infiltration rate when thoroughly wet. These consist chiefly of soils having a layer that impedes the downward movement of water or soils of moderately fine texture or fine texture. These soils have a slow rate of water transmission. Group D. Soils having a very slow infiltration rate (high runoff potential)when thoroughly wet. These consist chiefly of clays that have a high shrink-swell potential, soils that have a high water table, soils that have a claypan or clay layer at or near the surface, and soils that are shallow over nearly impervious material. These soils have a very slow rate of water transmission. If a soil is assigned to a dual hydrologic group (A/D, B/D, or C/D), the first letter is for drained areas and the second is for undrained areas. Only the soils that in their natural condition are in group D are assigned to dual classes. Rating Options Aggregation Method: Dominant Condition Component Percent Cutoff.None Specified Tie-break Rule: Higher USDA Natural Resources Web Soil Survey 2/7/2024 Conservation Service National Cooperative Soil Survey Page 5 of 5 CID C M Cid W w = e n Eli Iy - -'f3 �G - - + .-_�ems - T. 1 AREA t1 7' . , _,. _ �; _i'_[_-. s;. \ ` f - < 1 ,, ., I ii 00 I! 1 ' 0. 410 1 i i Fl J,o / , /} 1 _may; j 1 w' 3 c :,'- o PROJECT RE �.'' �;: .•.,. . " Ilr . y1,'/y.�y✓' y,� 'ay4' ",t'I+ N1 .{ 1 ,_ / ly 79 .2f C' 1[�' 11J•S//' iij . • ,Fr ,g. ��' � _.. '_ • .i , ,. - �\ \� --4 Ts i 4 L. __ _ ----„ „ ---,- , ,,.,/ , . , K Y I Y � r1-1 Li.- f r P a Ht AREA N�„ kL ',1 =xd 11 7 % z z w 1 .fill if. L -> Wpz ao lk �F 1 it 0 ,--1 � a • J` � C� x d '' a Wei ` ,yh e A O W / _. 1 I SITE DRAINAGE AREAS SCALE:1'=150' z 0 DRAINAGE AREA A a DRAINAGE AREA EXISTING IMPERVIOUS 66,551 SF=1.53 AC ¢ TOTAL DRAINAGE AREA-AREA'A" PROPOSED IMPERVIOUS 100,574 SF=2.31 AC RI 555,750 SF=12.75 AC. TOTAL IMPERVIOIIS 167,125 SF=3.84 AC ❑ PROJECT AREA W PROPOSED IMPERVIOUS IN PROJECT AREA: Q 100,574 SF=2.31 AC PERCENT IMPERVIOUS 30.11% DRAINAGE AREA B DRAINAGE AREA EXISTING IMPERVIOUS 28,024 SF=0.64 AC TOTAL DRAINAGE AREA-AREA'B'• PROPOSED IMPERVIOUS 73.648 SF=1.69 AC 984,353 SF=22.59 AC. TOTAL IMPERVIOUS 101,672 SF=2.33 AC W 0 PROJECT AREA DATE: JUNE 10. PROPOSED IMPERVIOUS IN PROJECT AREA: ARE THE PROPERTY Or CIVIL CONSULTANTS. 2024 73,648 SF=1.69 ACTHIS DRAWING AND TNE DESIGN XEIREON INC THE INFORMATION ON THIS DRAWING IS NOT FOR USE ON ANY OTHER SHE OR PROJECT PERCENT IMPERVIOUS 10.31% TNE REPRODUCTION OR 0-111E11 USE OF.15 DRAINAGE AREA C(NO CHANGE) DRAWING IN WHOLE OR IN PAPT.W11,10. DRAINAGE AREA TOTAL DRAINAGE AREA-AREA"C" WRITTEN CONSENTis PROHIBITED LTAurs'iuc.. COPYRIGHT 2021 CIVIL CONSULTANTS.INC. 2,776,900 SF=63.7 AC. PROJECT AREA IMPERVIOUS IN PROJECT AREA: SHEET NO. 12,614 SF=0.29 AC GRAPHIC SCALE PERCENT IMPERVIOUS 0.457100 0 USE GUIDELINES FOR A LOW DENSITY TREATMENT(GRASSED SWALE) m�_� (IN Fur) 1 inch=100 ft. 2:\Shared Folders\Projects\Corona\31004\DWG\Production\.SWM-DRAINAGE AREA-31009.dwg,11X17 POST RWH,6/10/202910:5,45 PM Exhibit 1 —Drainage Area Map for Pre-Development Conditions r >_ -. cA ..1_,. gi S o C —. = z -�..,�., '-' -� ,,. --� 2 _/ _�' /G�n I ,.,r^. l+�Y` �- `"_-,�,r �. - �_��- \"41 r ^ice ^ice/1 > a _ _ f _"iw- �_`__ - v\r_�un.� \ — �_--�.�i--�/�J\_�._-.�94--.---- _ice' -�3-- Cn VI - " --"J _-..•_`- , r asa—.-, —ass-•-r OAS ' - U $ w W P01 1g 1-e,� ��----'o-`'` vain w EXISTING RIGHT-OF-WAY 1 �� - �� '� �' H \_L `-, o \ \ 93 EXISTING EDGE OF PAVEMENT �L__ `7' o-=,, `,_ —,... ` ��_ --- 31 a in XI'0'� II ,— �/ -- ,9a� —ago_ — -a4a ill / 4'—":— - x / -- -- —,.ate--- +sz ---- — —wz_— '`—_ - ,Lem ae — _ - =-XF .r'' --- --xE- - x Sx° P / / / / /;- )I I I ) j I X / `''� '/�/ // /'/ - -/ _ r' 1 1 I / 1 I Fg. INV.=186.98 1 r' ,,e ' r41 x I I j r I ,/ ///' /j!\ v/- --�i,w3- -J_...-�\�//lae.-� `�\ ^\ ® I I 1 11 _ 1 �/ /� ' I :o x / I \,`\/� // //� -r✓'° <�� /i c `�/�\ o I 1 , /J \ -- - v 1 ,': 1 / J ✓1 ' / \ `.,, , \ i )0 - 0 I / / I 1 / l _ / � 1 X _/- r J/`' �\ ^ ^> vo'' rr/ (l�� - �` - --- , I / - — / �s - - I / /i I \�, I �'< - 1 "x I' / I -- ( \ I - / / it � �� \ I _ � � z I ' I 1 I x xw --1 —xw— \ xw----xw— / xw----xw— p I/ / ; I ®�----XW--- —XW---- F I r / / 1 ; 9e 0 1 i_ o I196 O I I 6 DATE: a y�r \� 2024 O 1 1// I1 I �" J �� EXISTING BUILDING HO IZ.SCALE: o \ (_L LII Z \ VERT.SCALE: I j II I a \ (77 E N/A p I I %v3 J� + \ _ , W PROJ.MANAGER: O I I I L/ /I -� U i Curve Number Calculations EXISTING LANDSCAPE-71—-1 --7--p 9 `r`/^3�'� _„W a1 DRAWN BY: W 1ir _ o Catchment Area(ac.) LandCover HSG Curve Number Composite CN 192 - Z PROJECT NO: Time of Concentration Calculations w a 1 0.19 Impervious B 98 18.8 2-year,24-hour rainfall depth(in.) 3.54 W O 1 0.00 Gravel,Fair B 85 0.0 EXIST Q'i al DRAWING NAME: Average Hydraulic p., O 1 0.00 Woods, Fair B 60 0.0 Catchment Flow Regime Length Land Cover Roughness Start Elev. End Elev. Time(min) SWM-31004.DWG Slope Radius 1 3L11 .48 Open Space,Fair B 69 239.9 // 1 Sheet Flow 100 Open 0.02 195.80 195.25 0.01 3.11 1>cc SHEET NO. • TOTAL 1 3.67 70.52 1 1 Shallow Concentrated Flow 283 Unpaved 195.25 186.98 0.03 1.71 EXHIBIT N Rounded CN 71 TOTAL 1 4.82 Exhibit 2—Drainage Area Map for Post-Development Conditions r 1 >- m r CCtr e = w 0 q ryr = z 2.._. "�'' _ . N" ) / �G"^l ��"I .-�... >eY .. ,ea�.� ^— —�—� 4S3 ^ice !I G�t1 d_ _ _per _-xis f �_"iw' —`__ -- . i-- / J�_ . -.�s4-_. +e - _-_-__- _-_�^J —�� .� r ,ya—.-, O:S � — — =a a o - f e D f --- "A` EXISTING RIGHT-OF-WAY - BLII / •�i . LIJ H P01 1 — — --, --- --- _ __ O =� `\ J EXISTING EDGE OF PAVEMENT ��__ `�' ��_�� ;� �^�'�_ ` _ - 1 * li Il i / .... _� ,-� e 1 OSX� y / _ / -192-- 992..... ,, ,, ,..- ,.. 191 �� > I I ), II J 'e! / � -_-_• _ — _ -..-- �� .4 ---may YI / /y I tea- GGG119J E _ �—— rs � _ — !e imiti_745474-0411=14210m...—___/": jiff .1°14.7 M.F7/,7Are--- 14..., '‘...A...*" I I i tqW=Th r (... , 1 i h I III Ix ' I " I 1/ 1/r /�Y� /ii',/, MIr Ii L _ I ) , i \-- z 101 aVi rar/ .WA/ 'WilZ V- Z / t i I '- I J 1 \ /' 1 , I 1.N_; , II I I' V �=j W V % A_ _ �' ( �,;\� % I,` 1 / //.W W#' /I' //// //.;/ ie t.�.1-- 0 �r93\--� - 0 2 ' �_r_ Imop I_A% AW I//.// firrf_ e / '- ( _ 1 / 1 ; A• 4Kr� �% Ii!�/ "��%� % �m��••r ems; _ _oo x I/ / I x / / If ________________xw__________ 2 \ 1 / /I A% % % iap / z I I I / /, 4 ,o, , , Arti.V . A44,,K— A% A - I Ar ,!..,,-- Am p r A -XW- ./ e A W Z,A 4Alerei04114FAVA1( dipcc :(1 • :: R Curve Number Calculations - AWN BY: w --EXISTING LANDSCAPE- P,9z , '� ,, 7 '�cti o Catchment Area(ac.) LandCover HSG Curve Number Composite CN _ - - �_/�, k\ / _,\ - _ r Z PROJECT NO: a. 1 2.92 Impervious B 98 286.4 `\ / 1 _ — / E / 0O A DRAWING NAME: W 1 0.00 Gravel,Fair B 85 0.0 EXISTING PAVEMENT 1 /lam _1 �- `.. - I _ i a SWM-31004.DWG O 1 0.00 Woods, Fair B 60 0.0 I(�^�_�_„__. � ` �, Tc — LESS THEN FIVE MINUTES \`` SHEET NO. w 1 0.75 Open Space,Fair B 69 51.5; // , i i r. \/ 1 • TOTAL 1 3.67 92.10 CC �� ir� EXHIBIT co Rounded CN 92 t / Exhibit 3 —SCS Curve Number for Volume Analysis WEST SIDE - POND 1 Hydrograph Report Hydraflow Hydrographs Extension for Autodesk®Civil 3D®by Autodesk, Inc.v2023 Monday,06/10/2024 Hyd. No. 2 Pre Dev 1 - West Hydrograph type = SCS Runoff Peak discharge = 4.761 cfs Storm frequency = 1 yrs Time to peak = 718 min Time interval = 2 min Hyd. volume = 9,713 cuft Drainage area = 3.670 ac Curve number = 71 Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = User Time of conc. (Tc) = 5.00 min Total precip. = 3.03 in Distribution = Type II Storm duration = 24 hrs Shape factor = 484 Pre Dev 1 - West Q (cfs) Hyd. No. 2 -- 1 Year Q (cfs) 5.00 5.00 4.00 4.00 3.00 3.00 2.00 2.00 1.00 1.00 L J0.00 , 0.00 0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560 Hyd No. 2 Time (min) Hydrograph Report Hydraflow Hydrographs Extension for Autodesk®Civil 3D®by Autodesk, Inc.v2023 Monday,06/10/2024 Hyd. No. 2 Pre Dev 1 - West Hydrograph type = SCS Runoff Peak discharge = 7.349 cfs Storm frequency = 2 yrs Time to peak = 718 min Time interval = 2 min Hyd. volume = 14,736 cuft Drainage area = 3.670 ac Curve number = 71 Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = User Time of conc. (Tc) = 5.00 min Total precip. = 3.68 in Distribution = Type II Storm duration = 24 hrs Shape factor = 484 Pre Dev 1 - West Q (cfs) Hyd. No. 2 -- 2 Year Q (cfs) 8.00 - 8.00 6.00 • 6.00 4.00 • 4.00 2.00 - • 2.00 0.00 - s - 0.00 0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560 Hyd No. 2 Time (min) Hydrograph Report Hydraflow Hydrographs Extension for Autodesk®Civil 3D®by Autodesk, Inc.v2023 Monday,06/10/2024 Hyd. No. 2 Pre Dev 1 - West Hydrograph type = SCS Runoff Peak discharge = 15.57 cfs Storm frequency = 10 yrs Time to peak = 718 min Time interval = 2 min Hyd. volume = 31,339 cuft Drainage area = 3.670 ac Curve number = 71 Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = User Time of conc. (Tc) = 5.00 min Total precip. = 5.51 in Distribution = Type II Storm duration = 24 hrs Shape factor = 484 Pre Dev 1 - West Q (cfs) Hyd. No. 2 -- 10 Year Q (cfs) 18.00 18.00 15.00 15.00 12.00 12.00 9.00 9.00 6.00 6.00 3.00 3.00 4114.".--- 0.00 0.00 0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560 Hyd No. 2 Time (min) Hydrograph Report Hydraflow Hydrographs Extension for Autodesk®Civil 3D®by Autodesk, Inc.v2023 Monday,06/10/2024 Hyd. No. 5 Post Dev 1 - West Hydrograph type = SCS Runoff Peak discharge = 13.00 cfs Storm frequency = 1 yrs Time to peak = 716 min Time interval = 2 min Hyd. volume = 27,345 cuft Drainage area = 3.670 ac Curve number = 92 Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = User Time of conc. (Tc) = 5.00 min Total precip. = 3.03 in Distribution = Type II Storm duration = 24 hrs Shape factor = 484 Post Dev 1 - West Q (cfs) Hyd. No. 5-- 1 Year Q (cfs) 14.00 14.00 12.00 12.00 10.00 10.00 8.00 8.00 6.00 6.00 4.00 - 4.00 2.00 - 2.00 0.00 - 0.00 0 120 240 360 480 600 720 840 960 1080 1200 1320 Hyd No. 5 Time (min) Hydrograph Report Hydraflow Hydrographs Extension for Autodesk®Civil 3D®by Autodesk, Inc.v2023 Monday,06/10/2024 Hyd. No. 5 Post Dev 1 - West Hydrograph type = SCS Runoff Peak discharge = 16.43 cfs Storm frequency = 2 yrs Time to peak = 716 min Time interval = 2 min Hyd. volume = 35,087 cuft Drainage area = 3.670 ac Curve number = 92 Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = User Time of conc. (Tc) = 5.00 min Total precip. = 3.68 in Distribution = Type II Storm duration = 24 hrs Shape factor = 484 Post Dev 1 - West Q (cfs) Hyd. No. 5-- 2 Year Q (cfs) 18.00 18.00 15.00 15.00 I 12.00 12.00 9.00 9.00 6.00 6.00 3.00 3.00 0.00 - 0.00 0 120 240 360 480 600 720 840 960 1080 1200 Hyd No. 5 Time (min) Hydrograph Report Hydraflow Hydrographs Extension for Autodesk®Civil 3D®by Autodesk, Inc.v2023 Monday,06/10/2024 Hyd. No. 5 Post Dev 1 - West Hydrograph type = SCS Runoff Peak discharge = 26.01 cfs Storm frequency = 10 yrs Time to peak = 716 min Time interval = 2 min Hyd. volume = 57,306 cuft Drainage area = 3.670 ac Curve number = 92 Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = User Time of conc. (Tc) = 5.00 min Total precip. = 5.51 in Distribution = Type II Storm duration = 24 hrs Shape factor = 484 Post Dev 1 - West Q (cfs) Hyd. No. 5 -- 10 Year Q (cfs) 28.00 28.00 24.00 24.00 20.00 20.00 16.00 16.00 12.00 12.00 8.00 8.00 4.00 4.00 0.00 ' 0.00 0 120 240 360 480 600 720 840 960 1080 1200 Hyd No. 5 Time (min) Hydrograph Report Hydraflow Hydrographs Extension for Autodesk®Civil 3D®by Autodesk, Inc.v2023 Monday,06/10/2024 Hyd. No. 8 Pond 1 Hydrograph type = Reservoir Peak discharge = 0.104 cfs Storm frequency = 1 yrs Time to peak = 1440 min Time interval = 2 min Hyd. volume = 15,669 cuft Inflow hyd. No. = 5 - Post Dev 1 - West Max. Elevation = 188.69 ft Reservoir name = <New Pond> Max. Storage = 25,443 cuft Storage Indication method used. Wet pond routing start elevation=184.00 ft. Pond 1 Q (cfs) Hyd. No. 8 -- 1 Year Q (cfs) 14.00 14.00 12.00 12.00 10.00 10.00 8.00 8.00 6.00 6.00 4.00 4.00 2.00 - - 2.00 0.00 — — 0.00 0 600 1200 1800 2400 3000 3600 4200 4800 5400 6000 Time (min) Hyd No. 8 Hyd No. 5 111111111 Total storage used = 25,443 cuft Pond Report Hydraflow Hydrographs Extension for Autodesk®Civil 3D®by Autodesk, Inc.v2023 Monday,06/10/2024 Pond No. 1 - <New Pond> Pond Data Contours-User-defined contour areas.Conic method used for volume calculation.Begining Elevation=181.78 ft Stage/Storage Table Stage(ft) Elevation(ft) Contour area(sqft) Incr.Storage(cuft) Total storage(cuft) 0.00 183.00 2,004 0 0 1.00 184.00 2,691 2,339 2,339 2.00 185.00 3,449 3,062 5,401 3.00 186.00 4,279 3,856 9,257 4.00 187.00 5,181 4,722 13,979 5.00 188.00 7,160 6,143 20,122 6.00 189.00 8,235 7,690 27,813 7.00 190.00 9,366 8,794 36,607 8.00 191.00 10,553 9,953 46,559 9.00 192.00 11,797 11,168 57,727 10.00 193.00 13,098 12,441 70,168 11.00 194.00 14,455 13,770 83,937 Culvert/Orifice Structures Weir Structures [A] [B] [C] [PrfRsr] [A] [B] [C] [D] Rise(in) = 18.00 1.25 Inactive 0.00 Crest Len(ft) = 36.00 10.00 0.00 0.00 Span(in) = 18.00 1.25 4.00 0.00 Crest El.(ft) = 189.78 191.65 0.00 0.00 No.Barrels = 1 1 1 0 Weir Coeff. = 3.33 2.60 3.33 3.33 Invert El.(ft) = 187.00 185.78 189.00 0.00 Weir Type = 1 Broad --- --- Length(ft) = 100.00 1.00 1.00 0.00 Multi-Stage = Yes No No No Slope(%) = 1.00 1.00 1.00 n/a N-Value = .013 .013 .013 n/a Orifice Coeff. = 0.60 0.60 0.60 0.60 Exfil.(in/hr) = 0.000(by Contour) Multi-Stage = n/a Yes No No TW Elev.(ft) = 0.00 Note:Culvert/Orifice outflows are analyzed under inlet(ic)and outlet(oc)control. Weir risers checked for orifice conditions(ic)and submergence(s). Stage(ft) Stage/Discharge Elev(ft) 12.00 195.00 10.00 193.00 8.00 191.00 6.00 189.00 4.00 187.00 2.00 185.00 0.00 183.00 0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0 90.0 100.0 110.0 120.0 Total Q Discharge(cfs) Hydrograph Report Hydraflow Hydrographs Extension for Autodesk®Civil 3D®by Autodesk, Inc.v2023 Monday,06/10/2024 Hyd. No. 8 Pond 1 Hydrograph type = Reservoir Peak discharge = 0.127 cfs Storm frequency = 2 yrs Time to peak = 1440 min Time interval = 2 min Hyd. volume = 23,206 cuft Inflow hyd. No. = 5 - Post Dev 1 - West Max. Elevation = 189.49 ft Reservoir name = <New Pond> Max. Storage = 32,133 cuft Storage Indication method used. Wet pond routing start elevation=184.00 ft. Pond 1 Q (cfs) Hyd. No. 8 -- 2 Year Q (cfs) 18.00 - 18.00 15.00 15.00 12.00 12.00 9.00 9.00 6.00 6.00 3.00 3.00 0.00 -, 0.00 0 600 1200 1800 2400 3000 3600 4200 4800 5400 6000 Time (min) Hyd No. 8 Hyd No. 5 111111111 Total storage used = 32,133 cuft Hydrograph Report Hydraflow Hydrographs Extension for Autodesk®Civil 3D®by Autodesk, Inc.v2023 Monday,06/10/2024 Hyd. No. 8 Pond 1 Hydrograph type = Reservoir Peak discharge = 8.629 cfs Storm frequency = 10 yrs Time to peak = 724 min Time interval = 2 min Hyd. volume = 45,277 cuft Inflow hyd. No. = 5 - Post Dev 1 - West Max. Elevation = 189.88 ft Reservoir name = <New Pond> Max. Storage = 35,589 cuft Storage Indication method used. Wet pond routing start elevation=184.00 ft. Pond 1 Q (cfs) Hyd. No. 8 -- 10 Year Q (cfs) 28.00 28.00 24.00 - 24.00 20.00 20.00 16.00 16.00 12.00 12.00 8.00 8.00 4.00 4.00 0.00 - — 0.00 0 360 720 1080 1440 1800 2160 2520 2880 3240 3600 Time (min) — Hyd No. 8 — Hyd No. 5 TTTTT1 II Total storage used = 35,589 cuft East Side - Pond 2 Hydrograph Report Hydraflow Hydrographs Extension for Autodesk®Civil 3D®2019 by Autodesk, Inc.v12 Tuesday,06/4/2024 Hyd. No. 2 Pre Dev 1 East Hydrograph type = SCS Runoff Peak discharge = 7.507 cfs Storm frequency = 1 yrs Time to peak = 718 min Time interval = 2 min Hyd. volume = 15,012 cuft Drainage area = 4.040 ac Curve number = 77 Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = User Time of conc. (Tc) = 5.00 min Total precip. = 3.03 in Distribution = Type II Storm duration = 24 hrs Shape factor = 484 Pre Dev 1 Q (cfs) Hyd. No. 2 -- 1 Year Q (cfs) 8.00 - 8.00 6.00 6.00 4.00 4.00 2.00 - 2.00 0.00 - ' 0.00 0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560 Hyd No. 2 Time (min) Hydrograph Report Hydraflow Hydrographs Extension for Autodesk®Civil 3D®2019 by Autodesk, Inc.v12 Tuesday,06/4/2024 Hyd. No. 2 Pre Dev 1 East Hydrograph type = SCS Runoff Peak discharge = 10.73 cfs Storm frequency = 2 yrs Time to peak = 718 min Time interval = 2 min Hyd. volume = 21,524 cuft Drainage area = 4.040 ac Curve number = 77 Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = User Time of conc. (Tc) = 5.00 min Total precip. = 3.68 in Distribution = Type II Storm duration = 24 hrs Shape factor = 484 Pre Dev 1 Q (cfs) Hyd. No. 2 -- 2 Year Q (cfs) 12.00 12.00 10.00 - 10.00 8.00 - 8.00 6.00 - 6.00 4.00 - 4.00 2.00 2.00 0.00 s '- 0.00 0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560 Hyd No. 2 Time (min) Hydrograph Report Hydraflow Hydrographs Extension for Autodesk®Civil 3D®2019 by Autodesk, Inc.v12 Tuesday,06/4/2024 Hyd. No. 2 Pre Dev 1 East Hydrograph type = SCS Runoff Peak discharge = 20.71 cfs Storm frequency = 10 yrs Time to peak = 716 min Time interval = 2 min Hyd. volume = 42,003 cuft Drainage area = 4.040 ac Curve number = 77 Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = User Time of conc. (Tc) = 5.00 min Total precip. = 5.51 in Distribution = Type II Storm duration = 24 hrs Shape factor = 484 Pre Dev 1 Q (cfs) Hyd. No. 2 -- 10 Year Q (cfs) 21.00 21.00 18.00 18.00 15.00 15.00 12.00 12.00 9.00 9.00 6.00 6.00 3.00 3.00 0.00 ' 0.00 0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 Hyd No. 2 Time (min) Hydrograph Report Hydraflow Hydrographs Extension for Autodesk®Civil 3D®2019 by Autodesk, Inc.v12 Tuesday,06/4/2024 Hyd. No. 5 Post Dev 1 EAST Hydrograph type = SCS Runoff Peak discharge = 11.92 cfs Storm frequency = 1 yrs Time to peak = 716 min Time interval = 2 min Hyd. volume = 24,271 cuft Drainage area = 4.040 ac Curve number = 87 Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = User Time of conc. (Tc) = 5.00 min Total precip. = 3.03 in Distribution = Type II Storm duration = 24 hrs Shape factor = 484 Post Dev 1 Q (cfs) Hyd. No. 5-- 1 Year Q (cfs) 12.00 12.00 10.00 - 10.00 8.00 1 - 8.00 6.00 - 6.00 4.00 - 4.00 2.00 2.00 0.00 ' 0.00 0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 Hyd No. 5 Time (min) Hydrograph Report Hydraflow Hydrographs Extension for Autodesk®Civil 3D®2019 by Autodesk, Inc.v12 Tuesday,06/4/2024 Hyd. No. 5 Post Dev 1 EAST Hydrograph type = SCS Runoff Peak discharge = 15.68 cfs Storm frequency = 2 yrs Time to peak = 716 min Time interval = 2 min Hyd. volume = 32,239 cuft Drainage area = 4.040 ac Curve number = 87 Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = User Time of conc. (Tc) = 5.00 min Total precip. = 3.68 in Distribution = Type II Storm duration = 24 hrs Shape factor = 484 Post Dev 1 Q (cfs) Hyd. No. 5-- 2 Year Q (cfs) 18.00 18.00 15.00 15.00 12.00 ` 12.00 9.00 9.00 6.00 6.00 3.00 3.00 — 0.00 0.00 0 120 240 360 480 600 720 840 960 1080 1200 1320 Hyd No. 5 Time (min) Hydrograph Report Hydraflow Hydrographs Extension for Autodesk®Civil 3D®2019 by Autodesk, Inc.v12 Tuesday,06/4/2024 Hyd. No. 5 • Post Dev 1 Hydrograph type = SCS Runoff Peak discharge = 26.35 cfs Storm frequency = 10 yrs Time to peak = 716 min Time interval = 2 min Hyd. volume = 55,680 cuft Drainage area = 4.040 ac Curve number = 87 Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = User Time of conc. (Tc) = 5.00 min Total precip. = 5.51 in Distribution = Type II Storm duration = 24 hrs Shape factor = 484 Post Dev 1 Q (cfs) Hyd. No. 5 -- 10 Year Q (cfs) 28.00 28.00 24.00 24.00 20.00 20.00 16.00 16.00 12.00 12.00 8.00 8.00 4.00 4.00 0.00 - 0.00 0 120 240 360 480 600 720 840 960 1080 1200 Hyd No. 5 Time (min) Hydrograph Report Hydraflow Hydrographs Extension for Autodesk®Civil 3D®2019 by Autodesk, Inc.v12 Tuesday,06/4/2024 Hyd. No. 8 Pond 2 Hydrograph type = Reservoir Peak discharge = 0.059 cfs Storm frequency = 1 yrs Time to peak = 1442 min Time interval = 2 min Hyd. volume = 11,059 cuft Inflow hyd. No. = 5 - Post Dev 1 Max. Elevation = 187.42 ft Reservoir name = <New Pond> Max. Storage = 28,450 cuft Storage Indication method used. Wet pond routing start elevation=186.31 ft. Pond 2 Q (cfs) Hyd. No. 8 -- 1 Year Q (cfs) 12.00 12.00 10.00 10.00 8.00 8.00 6.00 6.00 4.00 4.00 2.00 2.00 0.00 — 0.00 0 600 1200 1800 2400 3000 3600 4200 4800 5400 6000 Time (min) Hyd No. 8 Hyd No. 5 111111111 Total storage used = 28,450 cuft Pond Report Hydraflow Hydrographs Extension for Autodesk®Civil 3D®2019 by Autodesk, Inc.v12 Tuesday,06/4/2024 Pond No. 2 <New Pond> Pond Data Contours-User-defined contour areas.Conic method used for volume calculation.Begining Elevation=182.00 ft Stage/Storage Table Stage(ft) Elevation(ft) Contour area(sqft) Incr.Storage(cuft) Total storage(cuft) 0.00 182.00 2,748 0 0 1.00 183.00 3,526 3,129 3,129 2.00 184.00 4,361 3,936 7,064 3.00 185.00 5,252 4,799 11,863 4.31 186.31 6,200 7,492 19,355 5.00 187.00 8,265 4,973 24,328 6.00 188.00 11,579 9,875 34,203 7.00 189.00 18,344 14,831 49,034 8.00 190.00 20,852 19,583 68,616 Culvert/Orifice Structures Weir Structures [A] [B] [C] [PrfRsr] [A] [B] [C] [D] Rise(in) = 15.00 1.50 Inactive 0.00 Crest Len(ft) = 25.00 25.00 Inactive 0.00 Span(in) = 15.00 1.50 4.00 0.00 Crest El.(ft) = 187.75 188.00 0.00 0.00 No.Barrels = 1 1 1 0 Weir Coeff. = 3.33 2.60 3.33 3.33 Invert El.(ft) = 186.31 186.31 189.00 0.00 Weir Type = 1 Broad --- --- Length(ft) = 100.00 1.00 1.00 0.00 Multi-Stage = Yes No No No Slope(%) = 1.00 1.00 1.00 n/a N-Value = .013 .013 .013 n/a Orifice Coeff. = 0.60 0.60 0.60 0.60 Exfil.(in/hr) = 0.000(by Contour) Multi-Stage = n/a Yes Yes No TW Elev.(ft) = 0.00 Note:Culvert/Orifice outflows are analyzed under inlet(ic)and outlet(oc)control. Weir risers checked for orifice conditions(ic)and submergence(s). Stage(ft) Stage/ Discharge Elev(ft) 8.00 190.00 6.00 - 188.00 4.00 - 186.00 2.00 184.00 0.00 182.00 0.0 20.0 40.0 60.0 80.0 100.0 120.0 140.0 160.0 180.0 200.0 Total Q Discharge(cfs) Hydrograph Report Hydraflow Hydrographs Extension for Autodesk®Civil 3D®2019 by Autodesk, Inc.v12 Tuesday,06/4/2024 Hyd. No. 8 Pond 2 Hydrograph type = Reservoir Peak discharge = 0.202 cfs Storm frequency = 2 yrs Time to peak = 962 min Time interval = 2 min Hyd. volume = 16,251 cuft Inflow hyd. No. = 5 - Post Dev 1 Max. Elevation = 187.71 ft Reservoir name = <New Pond> Max. Storage = 31,385 cuft Storage Indication method used. Wet pond routing start elevation=186.31 ft. Pond 2 Q (cfs) Hyd. No. 8 -- 2 Year Q (cfs) 18.00 - 18.00 15.00 15.00 12.00 12.00 9.00 9.00 6.00 6.00 3.00 3.00 0.00 0.00 0 600 1200 1800 2400 3000 3600 4200 4800 5400 6000 Time (min) Hyd No. 8 Hyd No. 5 111111111 Total storage used = 31,385 cuft Hydrograph Report Hydraflow Hydrographs Extension for Autodesk®Civil 3D®2019 by Autodesk, Inc.v12 Tuesday,06/4/2024 Hyd. No. 8 Pond 2 Hydrograph type = Reservoir Peak discharge = 6.036 cfs Storm frequency = 10 yrs Time to peak = 724 min Time interval = 2 min Hyd. volume = 34,480 cuft Inflow hyd. No. = 5 - Post Dev 1 Max. Elevation = 188.00 ft Reservoir name = <New Pond> Max. Storage = 34,245 cuft Storage Indication method used. Wet pond routing start elevation=186.31 ft. Pond 2 Q (cfs) Hyd. No. 8 -- 10 Year Q (cfs) 28.00 28.00 24.00 24.00 20.00 20.00 I 16.00 16.00 12.00 12.00 8.00 8.00 4.00 4.00 0.00 - 0.00 0 240 480 720 960 1200 1440 1680 1920 2160 Time (min) Hyd No. 8 Hyd No. 5 111111111 Total storage used = 34,245 cuft Exhibit 4—Wet Pond Maintenance Procedures Operation & Maintenance Agreement Project Name: Project Gain' rr Project Location: 2120 NC 71, Maxton, NC 28364 Cover Page Maintenance records shall be kept on the following SCM(s). This maintenance record shall be kept in a log in a known set location. Any deficient SCM 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 pollutant removal efficiency of the SCM(s). The SCM(s)on this project include(check all that apply&corresponding O&M sheets will be added automatically): Infiltration Basin Quantity: Location(s): Infiltration Trench Quantity: Location(s): Bioretention Cell Quantity: Location(s): Wet Pond Quantity: a Location(s): East side of building tea. 44 e.tf'K Stormwater Wetland Quantity: Location(s): Permeable Pavement Quantity: Location(s): Sand Filter Quantity: Location(s): Rainwater Harvesting Quantity: Location(s): Green Roof Quantity: Location(s): Level Spreader- Filter Strip Quantity: Location(s): Proprietary System Quantity: Location(s): Treatment Swale Quantity: Location(s): Dry Pond Quantity: Location(s): Disconnected Impervious Surface Present: No Location(s): User Defined SCM Present: No Location(s): Low Density Present: No Type: I acknowledge and agree by my signature below that I am responsible for the performance of the maintenance procedures listed for each SCM above,and attached O&M tables. I agree to notify NCDEQ of any problems with the system or prior to any changes to the system or responsible party. Responsible Party: Mark Rogers Title&Organization: Associate VP Site Operations,Campbell Soup Supply Company LLI Street address: One Campbell Place City,state,zip: Camden,NJ 08103 Phone number(s): 877-858-3855 Email: mark_rogers@campbells.com Signature: )) ,, / Date: 5--ae—p�,�- I, tit- �Yl f. . • f(,U ,a Notary Public for the State off, n t 6County of /tZ iS 'S�' ,do hereby certify that /Vt• 1( tc 5 personally appeared before me this c2 day of /✓1 and acknowledge the due execution of the 0 ations and Maintenance AgCement. , Witness my hand and official seal, 444.k_ r++M��MW1111N *, 4.i:.A0CARy% " '�f•• 30% ��%.,�.,i My commission expires , /� 5 ; STORM-EZ 5/23/2024 Version 1.5 O&M Agreement Page 1 of 1 Wet Pond Maintenance Requirements Important operation and 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 pond should be fertilized of ter the initial fertilization that is required to establish the plants on the vegetated shelf. Stable groundcover will be maintained in the drainage area to reduce the sediment load to the wet pond. If the pond must be drained for an emergency or to perform maintenance, the flushing of - sediment through the emergency drain will be minimized as much as possible. At least once annually, a dam safety expert will inspect the embankment. Any problems that are found will be repaired immediately. 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. After the wet pond is established, it will be inspected quarterly and within 24 hours after every storm event greater than 1.0 inches (or 1.5 inches if in a Coastal County). Records of operation and maintenance shall be kept in a known set location and shall be available upon request. Inspection activities shall be performed as follows. Any problems that are found shall be repaired immediately. SCM element: Potential problem: How to remediate the problem: The entire wet pond Trash/debris is present. Remove the trash/debris. Areas of bare soil and/or Regrade the soil if necessary to remove the gully, plant The perimeter of the erosive gullies have ground cover and water until it is established. Provide lime wet pond formed. and a one-time fertilizer application. The inlet pipe is clogged (if applicable). Unclog the pipe. Dispose of the sediment off-site. The inlet pipe is cracked or otherwise damaged (if Repair or replace the pipe. The inlet device applicable). Regrade the swale if necessary and provide erosion Erosion is occurring in control devices such as reinforced turf matting or riprap to the swale (if applicable). avoid future problems with erosion. Sediment has Search for the source of the sediment and remedy the accumulated to a depth problem if possible. Remove the sediment and dispose of greater than the original it in a location where it will not cause impacts to streams or design depth for the SCM. sediment storage. The forebay - Provide additional erosion protection such as reinforced Erosion has occurred. turf matting or riprap if needed to prevent future erosion problems. Remove the weeds, preferably by hand. If pesticide is Weeds are present. used, wipe it on the plants rather than spraying. Wet Pond Maintenance Requirements (Continued) SCM element: Potential problem: How to remediate the problem: Sediment has Search for the source of the sediment and remedy the accumulated to a depth problem if possible. Remove the sediment and dispose of greater than the original it in a location where it will not cause impacts to streams or design sediment storage the SCM. depth. The main treatment Algal growth covers over Consult a professional to remove and control the algal area 50% of the area. growth. Cattails, phragmites or other invasive plants Remove the plants by wiping them with pesticide (do not cover 50% of the basin spray). surf ace. Best professional practices show that pruning is needed to Prune according to best professional practices. maintain optimal plant health. The vegetated shelf Determine the source of the problem: soils, hydrology, Plants are dead, disease, etc. Remedy the problem and replace plants. diseased or dying. Provide a one-time fertilizer application to establish the ground cover if a soil test indicates it is necessary. Remove the weeds, preferably by hand. If pesticide is Weeds are present. used, wipe it on the plants rather than spraying. Shrubs have started to grow on the Remove shrubs immediately. embankment. tviuciwc Vi iiiuoniaL Vi Consult a professional to remove muskrats or beavers and beaver activity is repair any holes or erosion. Pi t p�pp tiaJ JIai ICU IV The embankment grow on the Consult a dam safety specialist to remove the tree. am Honk mn ant An annual inspection by an appropriate professional shows that Make all needed repairs immediately. the embankment needs repair. Clean out the outlet device and dispose of any sediment in Clogging has occurred. a location where it will not cause impacts to streams or the The outlet device SCM. The outlet device is damaged. Repair or replace the outlet dev ice. vvccuo Vi V uiuincci trees are growing on the Remove the weeds or trees. rn at Floating wetland The anchor cable is island (if applicable) damaged, disconnected Restore the anchor cable to its design state. or missing. Wet Pond Maintenance Requirements (Continued) SCM element: Potential problem: How to remediate the problem: Erosion or other signs of damage have occurred Repair the damage and improve the flow dissipation at the outlet. structure. The receiving water Discharges from the wet pond are causing erosion Contact the local NCDEQ Regional Office. or sedimentation in the receiving water. Wet Detention Pond Design Summary Wet Pond Diagram WETPOND ID FOREBAY MAIN POND 2 Permanent Pool El. 186.31 Permanent Pool El. 186.31 Temporary Pool El: 187.75 Temporary Pool El: 187.75 Pretreatment other ' No Clean Out Depth: 4.31 Clean Out Depth: 4.31 than forebay? Sediment Removal El 182 Sediment Removal El 182 Has Veg.Filter? No Bottom Elevation: 182.5 Bottom Elevation: 182.5 WETPOND ID FOREBAY MAIN POND 1 Permanent Pool El. 185.58 Permanent Pool El. 185.58 Temporary Pool El: 189.78 Temporary Pool El: 189.78 Pretreatment other No Clean Out Depth: 3 Clean Out Depth: 3 than forebay? Sediment Removal El 182.58 Sediment Removal El 182.58 Has Veg.Filter? Bottom Elevation: 181.58 Bottom Elevation: 181.58 ATTACH ADDITIONAL SHEETS IF NECESSARY Exhibit 5—Wet Pond Supplemental Forms SUPPLEMENT-EZ COVER PAGE FORM$LQADEr PROJECT INFORMATION 1 Project Name Project Gain Larkspur 2 Project Area(ac) 8 3 Coastal Wetland Area(ac) 0 4 Surface Water Area(ac) 0 5 Is this project High or Low Density? High 6 Does this project use an off-site SCM? No COMPLIANCE WITH 02H.1003(4) 7 Width of vegetated setbacks provided(feet) 0 8 Will the vegetated setback remain vegetated? N/A 9 II BUA is proposed in the setback,does it meet NCAC 02H.1003(4)(c-d)? N/A 10 Is streambank stabilization proposed on this project? No NUMBER AND TYPE OF SCMs: 11 Infiltration System 12 Bioretention Cell 13 Wet Pond _ 2 14 Stormwater Wetland 15 Permeable Pavement --- 16 Sand Filter 17 Rainwater Harvesting(RWH) 18 Green Roof 19 Level Spreader-Fitter Strip(LS-FS) 20 Disconnected Impervious Surface(DIS) _ 21 Treatment Swale _ 22 Dry Pond 23 StormFilter 24 Silva Cell _ 25 Bayfitter 26 Filterra FORMS LOADED DESIGNER CERTIFICATION 27 Name and Title: William Akin,PE 28 Organization: _ Civil Consultants,Inc 29 Street address: 3708 Lyckan Parkway,Suite 201 30 City,State,Zip: Durham,NC 27707 31 Phone number(s): 919-490-1645 32 Email: randy.akin@civil-consultants.com Certification Statement I certify,under penalty of law that this Supplement-EZ form and all supporting information were prepared under my direction or supervision;that the information provided in the form is,to the best of my knowledge and belief,true,accurate,and complete;and that the engineering plans, specifications,operation and maintenance agreements and other supporting information are consistent with the information provided here. t7eslpner 00111 n7 frll�.rr, SEp�l_ i = Signature of Designer 045959 j s ''„,„/Aaili ll"►�t,_ `,, Date DRAINAGE AREAS 1 Is this a high density project? Yes 2 If so,number of drainage areas/SCMs 2 3 Does this project have low density areas? No 4 If so,number of low density drainage areas 0 Is all/part of this project subject to previous rule 5 versions? No o r, EHAC,tu DRAINAGE AREA INFORMATION Entire Site 1 2 4 Type of SCM Wet Pond Wet Pond 5 Total drainage area(sq ft) _ 159817 ~-175893 6 Onsite drainage area(sq ft) _ _ _ 159817 175893 7 Offsite drainage area(sq ft) _ - 0 0 8 Total BUA in project(sq ft) 127313 sf 110643 sf_ New BUA on subdivided lots(subject to 9 permitting)(sq ft) sf sf New BUA not on subdivided lots(subject to 10 permitting)(sf) 127313 sf 110643 sf 11 Offsite BUA(sq ft) sf sf 12 Breakdown of new BUA not on subdivided lots: -Parking(sq ft) 82854 sf 49958 sf -Sidewalk(sq ft) 4459 sf 1081 sf -Roof(sq ft) 59604 sf -Roadway lsq ft) —7-Future(sq ft) -Other,please specify in the comment box below(sq ft) New infiltrating permeable pavement on 13 subdivided lots(sq ft) sf sf New infiltrating permeable pavement not on 14 subdivided lots(sq ft) sf sf Existing BUA that will remain(not subject to 15 permitting)(sq ft) sf sf 16 Existing BUA that is already permitted(sq ft) sf sf 17 Existing BUA that will be removed(sq ft) sf sf 18 Percent BUA 80% 63% 19 Design storm(inches) 1.0 in 1.0 in 20 Design volume of SCM(cu ft) 10214 cf 9031 cf 21 Calculation method for design volume SA/DA SA/DA ADDITIONAL INFORMATION Please use this space to provide any additional information about the 22 drainage area(s): WET POND Drainage area number I 1 I 2 2 Minimum required treatment volume(cu ft) 10214 d 9031 cf GENERAL MDC FROM 02H.1050 3 Is the SCM sized to treat the SW from all surfaces at build-out? Yes Yes 4 Is the SCM located away from contaminated sods? Yes Yes 5 What are the side slopes of the SCM(H:V)? _ 3:1 3:1 6 Does the SCM have retaining walls,gabion walls or other No No engineered side slopes? 7 Are the inlets,outlets,and receiving stream protected from erosion Yes Yes (10-year storm)? 8 Is there an overflow or bypass for inflow volume in excess of the Yes Yes design volume? 9 What is the method for dewatering the SCM for maintenance? Pump(preferred) Pump(preferred)_ 10 If applicable,will the SCM be cleaned out after construction? Yes Yes , 11 Does the maintenance access comply with General MDC(8)? Yes Yes 12 Does the drainage easement comply with General MDC(9)? Yes Yes 13 If the SCM is on a single family lot,does(will?)the plat comply with N/A N/A General MDC(10)? ____ 14 Is there an O&M Agreement that complies with General MDC(11)? Yes Yes 15 Is there an O&M Plan that complies with General MDC(12)? Yes Yes 16 Does the SCM follow the device specific MDC? Yes Yes 17 Was the SCM designed px an NC licensed professional? Yes Yes WET POND MDC FROM 02H.1053 18 Sizing method used SA/DA SA/DA 19lHas a stage/storage table been provided in the calculations? Yes Yes Elevation of the excavated main pool depth(bottom of sediment20 181 78 182.00 removal)(fmsl) 21 Elevation of the main pool bottom(top of sediment removal)(fmsl) 182.78 183.00 22 Elevation of the bottom of the vegetated shelf(fmsl) 185.28 186.00 23 Elevation of the permanent pool(fmsl) 185.58 186.31 24 Elevation of the top of the vegetated shell(frnsl) 185.88 186.61 25 Elevation of the temporary pool(fmsl) 189.78 187.75 26 Surface area of the main permanent pool(square feet) 4990 6200 27 Volume of the main permanent pool(cubic feet) 13441 d 17613 cf 281Average depth of the main pool(feet) 3.50 ft 2.84 ft 29 Average depth equation used Equation 2 Equation 2 30 If using equation 3,main pool perimeter(feet) 31 If using equation 3,width of submerged veg.shelf(feet) 32 Volume of the forebay(cubic feet) 2494 d 3115 d 33 Is this 15-20%of the volume in the main pool? Yes Yes 34 Clean-out depth for forebay(inches) 12 in 12 in 35 Design volume of SCM(cu ft) 31086 d 17896 d 36 Is the outlet an orifice or a weir? Orifice Orifice 37 If orifice,orifice diameter(inches) 1 in 1 in 38 If weir.weir height(inches) 39 If weir.weir length(inches) 40 Drawdown time for the temporary pool(days) 2.88 2.22 41 Are the inlet(s)and outlet located in a manner that avoids short- Yes Yes circuiting? 42 Are berms or baffles provided to improve the flow path? Yes Yes 43 Depth of forebay at entrance(inches) 48 in 48 in 44 Depth of forebay at exit(inches) 48 in 48 in 45 Does water flow out of the forebay in a non-erosive manner? Yes Yes 46 Width of the vegetated shelf(feet) 6 ft 6 ft 47 Slope of vegetated shell(H:V) 10:1 10:1 a6 Does the orifice drawdown from below the top surface of the No No permanent pool? 49 Does the pond minimize impacts to the receiving channel from the I. Yes Yes yr,24-hr storm? 50 Are fountains proposed?(If Y,please provide documentation that No No MOC(9)is met.) 51 Is a trash rack or other device provided to protect the outlet system? Yes Yes 52 Are the dam and embankment planted in non-clumping turf grass? Yes Yes 53 Species of turf that will be used on the darn and embankment 54 Has a planting plan been provided for the vegetated shelf? Yes Yes ADDITIONAL INFORMATION Please use this space to provide any additional information about 55 the wet pond(s): Wet Pond 1 Drains drainage area B:Wetpond 2 draings drainage area A Wet Pond 1 3 8:40 AM 6/11/2024