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Home My WebLink AboutRaleigh Regional Office - 17-158 Farmville Public Library - STMWM Narrative CONTENTS Design Narrative Maps Quad Map Soils Map FEMA Firm Map Supporting Calculations NOAA Atlas14 Storm Drainage System Stormwater Management Design Narrative Farmville Public Library CLH Project No.: 17-158 February 2019 PROJECT DESCRIPTION Farmville Public Library is an existing public library that is proposed to undergo a complete site and building renovation. The facility is located in the Town of Farmville, North Carolina, on the southeast corner of S Walnut Street and W Church Street. Refer to Quad Map. The 0.51-ac site, which consists of an existing building with two parking areas and sidewalks, will be demolished. The proposed improvements consist of the following: new library building, outdoor seating areas, two book drop-off parking stalls, parking area, and associated construction of storm drainage, utility relocation, curb and gutter, sidewalks, landscaping, etc. NC DEQ was contacted to determine if the site had an existing stormwater permit; however, it is believed that the original 1950’s library predates the current regulations. Farmville Public Library will be closed during construction. The disturbed area for this project will be approximately 0.78-ac, which encroaches into the right-of-way (ROW) of Walnut Street, W Church Street, and the neighboring properties. The project will result in a net decrease in built upon area (BUA) on site from 0.42-ac to 0.37-ac. Soils on the site consist of Norfolk sandy loam (NrA – hydrologic soil group A). Refer to Soils Map. Surface water features are not present on the site. The site mostly drains southwest, towards W Church Street, and is located in the Neuse River Basin. FEMA FIRM #3720461700K and #3720462700K dated April 16, 2013 indicates that the site is outside the 100-year flood plain. Refer to the FEMA Firm Map. STORMWATER MANAGEMENT Farmville Public Library is located in the Town of Farmville and must go through State Post- Construction Stormwater permitting. According to 15A NCAC 02H.1001, redevelopment as defined in G.S. 143-214.7(a1) is not subject to stormwater management programs. G.S. 143-217.7(a1) defines redevelopment as “any land-disturbing activity that does not result in a net increase in built-upon area and that provides greater or equal stormwater control to that of the previous development”. Since the redevelopment of Farmville Public Library will reduce the BUA by 0.05-ac and provide equal stormwater control, no additional stormwater treatments are proposed. MAPS USGS The National Map: Orthoimagery. Data refreshed October, 2017. National Flood Hazard Layer FIRMette 0 500 1,000 1,500 2,000250Feet Ü77°35'33.50"W 35°36'3.03"N 77°34'56.05"W35°35'33.77"N SEE FIS REPORT FOR DETAILED LEGEND AND INDEX MAP FOR FIRM PANEL LAYOUT SPECIAL FLOODHAZARD AREAS Without Base Flood Elevation (BFE)Zone A, V, A99With BFE or Depth Zone AE, AO, AH, VE, AR Regulatory Floodway 0.2% Annual Chance Flood Hazard, Areasof 1% annual chance flood with averagedepth less than one foot or with drainageareas of less than one square mile Zone X Future Conditions 1% AnnualChance Flood Hazard Zone XArea with Reduced Flood Risk due toLevee. See Notes.Zone X Area with Flood Risk due to Levee Zone D NO SCREEN Area of Minimal Flood Hazard Zone X Area of Undetermined Flood Hazard Zone D Channel, Culvert, or Storm SewerLevee, Dike, or Floodwall Cross Sections with 1% Annual Chance17.5 Water Surface ElevationCoastal Transect Coastal Transect BaselineProfile BaselineHydrographic Feature Base Flood Elevation Line (BFE) Effective LOMRs Limit of StudyJurisdiction Boundary Digital Data Available No Digital Data Available Unmapped This map complies with FEMA's standards for the use of digital flood maps if it is not void as described below. The basemap shown complies with FEMA's basemap accuracy standards The flood hazard information is derived directly from theauthoritative NFHL web services provided by FEMA. This mapwas exported on 1/15/2019 at 10:16:03 AM and does notreflect changes or amendments subsequent to this date andtime. The NFHL and effective information may change orbecome superseded by new data over time. This map image is void if the one or more of the following mapelements do not appear: basemap imagery, flood zone labels,legend, scale bar, map creation date, community identifiers,FIRM panel number, and FIRM effective date. Map images forunmapped and unmodernized areas cannot be used forregulatory purposes. Legend OTHER AREAS OFFLOOD HAZARD OTHER AREAS GENERALSTRUCTURES OTHERFEATURES MAP PANELS 8 1:6,000 B 20.2 The pin displayed on the map is an approximate point selected by the user and does not represent an authoritative property location. SUPPORTING CALCULATIONS STORM DRAINAGE / HYDRAULIC GRADE LINEDATEDESIGN PHASEANALYSIS1/14/2019PRELIM/x /PROJECT NAMEPROJECT NO CONSTR/ /Farmville Public Library17-158REVISION/ /LOCATIONBYRECORD/ /Farmville, NCDALOTHER/ /CHECKED BY (SPECIFY)SJMn= 0.013 STORM DRAINAGE SCHEDULE CONTINUEDg= 197 h= 20I= 7.88INLETTc I CcINLET INLET Cc INLET TOTAL INLET PIPE TIME RUNOFFFROM TO AREA AREA IMPERVIOUS RUNOFF DISCHARGE AREAS TIME TIME OF CONC. INTENSITY COEFF.(SF) (AC) (%) COEFF. (CFS) (AC) (MIN) (MIN) (MIN) (IN/HR)A1 A2 1,900 0.04 85 0.85 0.29 0.04 5.00 0.00 5.00 7.88 0.85A2 A3 1,060 0.02 85 0.85 0.16 0.07 5.00 0.05 5.05 7.86 0.85A3 A4 13,320 0.31 99 0.94 2.27 0.37 5.00 0.41 5.41 7.75 0.93A4 A5 1,760 0.04 100 0.95 0.30 0.41 5.00 0.82 5.82 7.63 0.93A40 A4 1,270 0.03 98 0.94 0.22 0.03 5.00 0.00 5.00 7.88 0.94A50 A5 2,180 0.05 55 0.66 0.26 0.05 5.00 0.00 10.00 6.57 0.66A500 A5 2,070 0.05 70 0.76 0.28 0.05 5.00 0.00 10.00 6.57 0.76B1 B2 3,750 0.09 90 0.89 0.60 0.09 5.00 0.00 5.00 7.88 0.8917-158 STRM-1-INVERTSSTORM Page 1 of 4 n= 0.013g= 197h= 20I= 7.88FROM TOA1 A2A2 A3A3 A4A4 A5A40 A4A50 A5A500 A5B1 B2STORM DRAINAGE / HYDRAULIC GRADE LINEDATEDESIGN PHASEANALYSIS1/14/2019PRELIM/x /PROJECT NAMEPROJECT NO CONSTR/ /Farmville Public Library17-158REVISION/ /LOCATIONBYRECORD/ /Farmville, NCDALOTHER/ /CHECKED BY (SPECIFY)SJM STORM DRAINAGE SCHEDULE - CONTINUED Q QUPSTREAMSIDE-CAPACITY SEGMENT UPPER LOWER TOP PIPEDISCHARGE STREAM SLOPE DIA. (FULL) V FULL LENGTH TIME INV. INV. ELEV. COVER(CFS) (CFS) (IN) (CFS) (FPS) (FT) (MIN) (FT) (FT) (FT) (FT)0.29 0.00 0.0125 8 1.4 3.9 12 0.05 81.00 80.85 83.75 2.020.46 0.00 0.0049 15 4.5 3.7 79 0.36 79.80 79.41 84.05 2.892.69 0.00 0.0050 15 4.6 3.7 92 0.41 79.31 78.85 83.20 2.533.15 0.22 0.0043 15 4.2 3.4 82 0.40 78.75 78.40 83.30 3.190.22 0.00 0.0107 8 1.3 3.6 70 0.33 79.80 79.05 82.50 1.970.22 0.00 0.0105 8 1.2 3.5 95 0.45 79.80 78.80 82.50 1.970.24 0.00 0.0108 8 1.3 3.6 60 0.28 79.80 79.15 82.50 1.970.60 0.00 0.0108 8 1.3 3.6 60 0.28 79.00 78.35 82.00 2.2717-158 STRM-1-INVERTSSTORM Page 2 of 4 n= 0.013g= 197h= 20I= 7.88FROM TOA1 A2A2 A3A3 A4A4 A5A40 A4A50 A5A500 A5B1 B2STORM DRAINAGE / HYDRAULIC GRADE LINEDATEDESIGN PHASEANALYSIS1/14/2019PRELIM/x /PROJECT NAMEPROJECT NO CONSTR/ /Farmville Public Library17-158REVISION/ /LOCATIONBYRECORD/ /Farmville, NCDALOTHER/ /CHECKED BY (SPECIFY)SJM HYDRAULIC GRADE LINE CONTINUEDBEND LOSS K's90° = 0.70 70° = 0.61 50° = 0.47 30° = 0.28 20° = 0.1680° = 0.6660° = 0.5540° = 0.3825° = 0.2215° = 0.10PIPE HYDRAULIC SIDESTREAM HEAD LOSSBEND FRICTION FRICTIONAREA RADIUS SUMMATION Hf Hc He Hb Ht LOSS SLOPE VELOCITY(FT) (FT) (CFS)K (FT/FT) (FPS)0.3491 0.1667 0.00 0.01 0.00 0.00 0.00 0.01 0.00 0.0006 0.841.2272 0.3125 0.00 0.00 0.00 0.00 0.01 0.02 0.70 0.0000 0.371.2272 0.3125 0.00 0.16 0.02 0.00 0.00 0.18 0.70 0.0017 2.181.2272 0.3125 0.22 0.19 0.03 0.03 0.01 0.26 0.16 0.0024 2.560.3491 0.1667 0.00 0.02 0.00 0.00 0.00 0.02 0.00 0.0003 0.620.3491 0.1667 0.00 0.03 0.00 0.00 0.00 0.03 0.00 0.0003 0.620.3491 0.1667 0.00 0.02 0.00 0.00 0.00 0.02 0.00 0.0003799580.670.3491 0.1667 0.00 0.15 0.01 0.00 0.00 0.16 0.00 0.0025 1.7217-158 STRM-1-INVERTSSTORM Page 3 of 4 n= 0.013g= 197h= 20I= 7.88FROM TOA1 A2A2 A3A3 A4A4 A5A40 A4A50 A5A500 A5B1 B2STORM DRAINAGE / HYDRAULIC GRADE LINEDATE DESIGN PHASEANALYSISPRELIM/x /PROJECT NAMEPROJECT NO CONSTR/ /Farmville Public Library17-158REVISION/ /LOCATIONBY RECORD/ /Farmville, NCDALOTHER/ /CHECKED BY (SPECIFY)SJMDESIGN CRITERIA: HYDRAULIC GRADE LINE - CONTINUED 1. DESIGN FOR THE 10 YR STORM2. ASSUME TIME OF CONCENTRATION TOAN INDIVIDUAL INLET = 5 MIN.INLET W.S. ELEV.3. INTENSITY = g/(h+T), FOR 10 YR STORMOUTLET OUTLET INLET USE FLOW FREE- UPSTREAM4. MANNINGS "n" FACTOR= .013W.S. ELEV CONTOL CONTROL CONDITION BOARD INLET COMMENTS5. RATIONAL METHOD: C= .30 GRASS, C= .95 PAVEMENT(FT) (FT) (FT) (FT) CONTROL (FT) TYPE80.85 80.86 81.36 81.36 INLET 2.39 YI OK80.14 80.16 80.43 80.43 INLET 3.12 CB OK79.66 79.84 80.14 80.14 INLET 2.56 CB OK79.40 79.66 79.66 79.66 INLET 3.64 MH OKTailwater Elev= 79.4079.66 79.68 80.15 80.15 INLET 2.35 YI OKTailwater Elev= 79.6679.40 79.43 80.15 80.15 INLET 2.35 YI OKTailwater Elev= 79.4079.68 79.71 80.15 80.15 INLET 2.35 YI OKTailwater Elev= 79.6878.88 79.04 79.46 79.46 INLET 2.54 YI OKTailwater Elev= 78.881/14/201917-158 STRM-1-INVERTSSTORM Page 4 of 4