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Home My WebLink AboutWPO202200029 Calculations 2022-07-11MONTICELLO CONTEMPLATIVE SITE COUNTY OF ALBEMARLE, VIRGINIA DESIGN CALCULATIONS & NARRATIVE REF. WP02022000xx JULY 19 2022 • TIMMONS GROUP YOUR VISION ACHIEVED THROUGH OURS. Prepared by: Kimberly Roeser, PE Timmons Group 608 Preston Ave, Suite 200 Charlottesville, VA 22903 434.327.1685 Kimberly A Roeser 7 be. No. 63054 a 111 11Z G?� Table of Contents Section Title Project Narrative 2 LD 229 — Storm Sewer Design Computations LD 204 — Storm Inlet Design Computations 4 LD 347 — Hydraulic Grade Line Computations Virginia Runoff Reduction Method Worksheet Summary Proiect Narrative: This project includes the construction of a new walking path, as well as associated landscaping. The limits of disturbance totals 0.39 acres. Stormwater ManaEement: Water Quality In the pre -developed condition, the site is an undeveloped area (0.39 acres managed turf). In the proposed condition, there will be 0.11 acres of impervious cover and 0.28 acres of managed turf. Per the Virginia Runoff Reduction Spreadsheet, this development will require that 0.21 lbs. of phosphorus be removed per year. Nutrient credits will be purchased to meet stormwater quality requirements. Water Quantity In existing condition, the entire site drains towards the southwest. In the developed condition, the runoff from the disturbed area will maintain the existing drainage pattern and drain towards the southwest as sheet flow. A level spreader is provided at the point of concentrated discharge to return runoff to sheet flow. Therefore, this project fulfills the requirements of section 9VAC25-970-66 Section D. LD229 STORM SEWER DESIGN COMPUTATIONS STORM FREQUENCY 70 PROJECT: Monticello Contemplative Site LOCATION: COUNTY: Albemarle Designed by: Checked by: UNITS ENGLISN PIPE NO FROM POMT TO POINT DRAM. AREA "A" Acre (3) RUNOFF COEFF, "C" (4) CA TOTAL INLET TIME Minutes (9) RAM FALL 1n (8) RUNOFF Q CPS (9) INVERTELEVATIONS LENGTH of Pipe Ft (12) SLOPE Ft/Ft. (13) SIZE (Dia. Or SpaNRise) In. (14) SHAPE Capacity CPS (15) Friction Slope FUFt. VEL V. PUS. (16) FLAW UME Min (19) REMARKS (I8) INCRE-ACCUM- MENT (5) ULATED (6) ADDTL CA UPPER END (10) LOWER END (11) REFERENCE (I) STA. REFERENCE (2) STA. IH 112 110 042/ 0450 0.192 0.192 0.000 6000 6230 1.197 830628 830"0 18778 0010 120W Circular 3858 0001 4.343 0On 109 110 108 0009 0.850 0NO, 0-1" 0.000 6-012 6209 1235 830338 830.130 20988 0-010 12000 Circular 3858 0001 44381 00/9 109 108 106 0000 O.OW 0.000 0.199 0-000 6151 6186 1231 830030 829-690 A1 366 0-010 12000 Cimular 3858 0001 44376 0.13/ 105 106 102 0000 O.OW 0000 0.199 0-000 6288 6146 Im 829569 829160 40942 0-010 12000 Cimuar 3-858 0001 4369 0.156 103 1M 102 0588 0450 0265 0265 0-000 6-000 6230 1"a 829657 829J60 24.868 0-020 120W Cimular 545I 0002 6098 0068 101 102 100 0000 0000 OOco oa64 0000 6445 6.102 2829 829055 828.800 8SI2 0030 12000 Cimuar 6683 0005 8.193 RRn FORM LO 201 STORMWATER INLET COMPUTATIONS SHEET 1 OF ROU PROJECT Mon lb come plal eSlle DESIGNER: KAM DATE 711aOM CHECKED: UNITSAGUSH INLETSOFT BY ENSOFTEC DATE711I LD347 PROJECT: Monticello Contemplative Site DESIGNED BY: HYDRAULIC GRADE LINE ANALYSIS Checked: INCIDENCE PROBABILITY 10 Year INLET OR JUNCTION INLET STATION OUTLET WATER SURFACE ElEV DIA PIPE Do (In) DESIGN DISCH. Go (CFS) LENGTH PIPE LO (ED FRICTION SLOPE. SW (FT/M FRICTION LOSS Hf (ED JUNCTION LOSS FINAL H (Ft) Inkt Waled su a E.H. RM Ek Coom V. Ho (R) OI N OM N'32g HI Ante HA HI 1.3 HI OE HI 102 $29.6 12 2.83 8.51 0.54% 0.05 8.17 0.26 1.65 6.1 10.05 0.58 0.2 89.59 0.21 0.67 0 TRUE 0.38 829.98 832.06 OK -2.08 106 829.98 12 1.22 40.94 0.10% 0.04 4.37 0.07 1.23 4.38 5.39 0.3 0.1 12.11 0.D4 0.22 0 TRUE 0.15 830.13 833.77 OK -3.64 108 830.47 12 1.23 36.02 0.10% 0.04 4.38 0.07 1.24 4.38 5.41 0.3 0.1 67.57 0.18 0.36 0 TRUE 0.22 830.69 834.44 OK -3.75 110 830.93 12 1.24 20.79 0.10% 0.02 4.38 0.07 1.2 4.34 5.2 0.29 0.1 68.04 0.18 0.36 0 TRUE 0.2 831.13 835.35 OK 4.22 112 831.24 12 1.2 18.78 0.10% 0.02 4.34 0.07 0 0 0 0 0 0 0 0.07 0.1 TRUE 0.07 831.31 834.68 OK -3.37 104 831.T 12 1.65 24.87 0.18% 0.05 6.1 0.14 0 0 0 0 0 0 0 0.14 0.19 TRUE 0.14 831.91 833.37 OK -1.45 DEQ Virginia Runoff Reduction Method Re -Development Compliance Spreadsheet - Version 3.0 02011 BMP Standards and Specifications 02013 Draft BMP Standards and Specifications data input cells Project Name: MONTICELLO CONTEMPLATIVE SITE Date: 5/27/2022 constant values Linear Development Project? No calculation cells Site Information Post -Development Project (Treatment Volume and Loads) Enter Total Disturbed Area (acres) -> D.39 Check., BMP Design Specifications List. 2013 Draft Stds & Specs Maximum reduction required. Lineorproject? No The site's net increase in impervious cover (acres) is: Land cover areas entered correctly? Post -Development '® Total disturbed area entered? ./ Pre-ReDevelopment Land Cover (acres) A sails BSoils CSoils Dsoils Totals Forest/Open Space (acres) -- undisturbed forest/open space OAO Managed Tort (acres) -- disturbed, graded for yards or other turf to be mowmed/anaged 0.39 0.39 Impervious Cover (acres) ON 0.00 0.39 Post -Development Land Cover (acres) A Soils BSoils CSoils Dsoils Totals Forest/Open Space (acres) -- undisturbed, protected forest/open space or reforested land 0.00 Managed Tud (acres) -- disturbed, graded for yards cur other turf to be mowed/managed 0.28 0.28 Impervious Cover (acres) 0.11 0.11 Area Check OR. OR. OR. OR. 0.39 Constants Runoff Coefficients Rv Annual Randall (inches) 43 ASoils BSoils CSoils Dsoils Target Rainfall Event (inches) IN Forest/Open Space 0.02 0.03 0.04 0.05 Total Phosphorus (TP) EMC(mg/L) 0.26 Managed Turf 0.15 0.20 0.22 0.25 Total Nitrogen (TN) EMC Img/L) 1.86 Impervious Cover 0.95 0.95 0.95 0.95 Target TP Load (lb/acre/W) 0.41 Pj(unitless correction factor) 0.90 mul TI:r= LAND COVER SUMMARY POST DEVELOPMENT Land Cover Summary -Pre Land Cover Summary-Post(Final) Land Cover Summary -Post Laird Cover Summnry-Post Pre-ReDevelopment Listed Adjusted' Post Renee. & New ImperviousPOSt-R•Developmen[ Pont -Development New Impervious Forest/Open Space Forest/Open Space Forest/Open Space Cover (acres) 0.00 0.00 0 0 .00 Cover (acres) Coast (a.) Weighted Rv(farest) OAO ON Weighted Rv(forest) ON Weighted Faltered) 0.00 %Forest 0% 0% %Forest 0% %Forest 0% Managed Turf Cover (acres) 0.39 0.28 Managed Turf Cover 028 Managed Tud Cover 028 (acres) (acres) Weighted Rv(turf) 0.20 0.20 Weighted Far (turf) 0.20 Weighted Rv(turq 0.20 %Managed Turf 100% IN% %Managed Turf 72% %Managed Tuff 100% Impervious Cover (acres) ON ON Impervious Cover (acres) 0.11 Re (acres) s 000 New Impervious Cover 0.11 Cove Cover (acres) (acres) Rv(impervious) 0.95 0.95 Rv(im"mious) 0.95 Rv(impervious) 0.95 Rv(impervious) 0.95 %Impervious 096 0% %Impervious 28% %Impervious 0% Total She Area lames) 0.39 0.28 Final Are Area (acres) 0.39 Total genes. $he Mea 0.28 Site Be 0.20 0.20 Final Post D. Site Re 0.41 Renee Site Rv 0.20 Treatment Volume and Nutrient Load Treatment Volume and Post-ReDevelopment Nutrient Load amen Pre-Rellevelo t Treatment Volume Final Post -Development Pont -Development (acre-k) IONS 0.0047 Treatment Volume (acre-k) 0.0134 Treatment Volume (acre-ft) 0.0047 Treatment Volume (acre-k) 0.0087 amen Pre-Rellevelo t Treatment Volume Final Port -Development Post-ReDevelopment Post -Development (cubic feet) 283 203 Treatment Volume 583 Treatment Volume 203 Treatment Volume(nrbic 379 (cubic feet) (cubicfeet) feet) Pre-ReDevelopment TP Load Final Post. Post-ReDevelopment Post -Development TP bad (lb/yr) 0.18 0.13 Developmen[TP Load 0.37 Load (TP) 0.13 (lb/yr) 0.24 (Ib/yr) (IbIW)" Pre-Renevelopmen[ TP Load per acre Final Poo -Development TP PoSPRenevelopment TP pmer,Tyr) OA6 0.46 Load per acre D.9a Load me acre D.4B pb/we/nl (lb/acre/,) Baseline TP Load (lb/yr) Max. Reduction Required (0.41 lbs/acre/yr applied to pre -redevelopment area excluding pervious 0.11 (Below Pre- 10% land proposed for new impervious cover) ReDevelopment bad) 'Adjusted Land CoveSumma r % ry. TP Load Reduction TP Load Reduction Pre ReDevelopment land rover minus pervious land coverer resL/open spare or monagetl Required for 0.01 Required for New 0.19 turf/ ocreagepmposedfornewimpervious cover Redeveloped Area Redeveloped Area (lb/yr) (Ib/yr) Adjusted total acreage is consistent wilt Post-ReDevelopment acreage (minus acreage of new impervious rover). Column I shows load redu ntlon requnement for new impervious cover (hosed on new developmentloadlimiq 0.41 Ihs/acre/year). Post -Development Requirement for TP Load Reduction Required (16/yr) 0.21 Nitrogen Loads (Informational Purposes Only) Final Pos -Development TN bad Pre-ReDevelopment TN Wad(lb/yr) 1.27 IPoaL-ReDevelopment&Newlmpervious) 2.62 Ib/yr) Site ulta(Water Quality Compliance) Area LM1x amlay w nlay nMe or uyyMe or aMa TwaMwitt VMumelR°I RunoR MJuaim Volume and TP By P'aWRe Area mlx'I wmO ne l�xMl u%u l�xMl TotalP Ihlns mao0Yn1 am ONnI reenOYnl- eml�xMt Total MWogan lau lrl rm4un Puryme[I maolVvrl MO I�xMI mm ObM Virginia Runoff Reduction Method Workshest DEC, Virginia Runoff Reduction Method Re -Development Compliance Spreadsheet - Version 3.0 LIMP Design Specifications List: 2013 Draft Stds & Specs Site Summary Project Title: MONTICELLO CONTEMPLATIVE SITE Date: 44708 Total Rainfall (in): 43 Total Disturbed Acreage: 0.39 Site Land Cover Summary Pre-ReDevelopment Land Cover (acres) Asoils BSolls CSolls DSolis Totals %of Total Forest/Open (acres) 0.00 0.00 0.00 0.00 0.00 0 Managed Turf(acres) 0.00 1 0.39 0.00 0.00 0.39 100 Impervious Cover (acres) 0.00 0.00 0.00 0.00 0.00 0 0.39 100 Post-ReDevelopment Land Cover (acres) Asoils BSoils CSolls DSoils Totals %of Total Forest/Open (acres) 0.00 0.00 0.00 0.00 0.00 0 Managed Turf(acres) 1 0.00 0.28 0.00 0.00 0.28 72 Impervious Cover (acres) 0.00 0.11 0.00 0.00 0.11 28 0.39 100 Site Tv and Land Cover Nutrient Loads Final Port -Development Post- post- Adjusted Pre- (Post-ReDevelopment ReDevelopmem Developmentm ReDevelopment ervious & New I p ) (New Impervious) Site Rv 0.41 0.20 0.95 0.20 Treatment Volume(ft) 583 203 379 203 TP Load(lb/yr) 0.37 0.13 0.24 0.13 Total TP Load Reduction Required (lb/yr) 0.21 0.01 0.19 Final Post-Developmem Load (Post-ReDevelopment & New Impervious) Pre- ReDevelopment TN Load (Ib/yr) 2.62 1.27 Pre, ReDevelopment Final Post -Development TP Load per acre TP Load per acre :S1 (Ib/acre/yr) (Ih/acre/yr) 0.46 0.94 Summary Print Virginia Runoff Reduction Method] Woftheet Site Compliance Summary Maximum% Reduction Required Below 10% Pre-ReDevelopment Load] Total Runoff Volume Reduction (k') 0 Total TP Load Reduction Achieved (lb/yr) 0.00 Total TN Load Reduction Achieved (lb/yr) 0.00 Remaining Post Development TP Load 0.37 (lb/yr) Remaining TP Load Reduction (lb/yr) 0.21 Required Summary Print