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Home My WebLink AboutWPO201800045 Calculations 2018-07-24MEMORANDUM — Minor Hill Hydrologic Analysis i739 .'allied St., Suite A Charlottesville, VA 22903 i6 540.239.1-428 www.ecosystemservices.us info @ccosystcniscrvices. us July 24, 2018 FROM: Ecosystem Services, LLC SUBJECT: Minor Hill Hydrologic Analysis Overview — Objectives, Procedure, and Outputs Objectives: • Create a calibrated existing conditions hydrologic model • Iterate a proposed conditions hydrologic model for design while keeping proposed outflows equivalent to the original design discharge for the 10-year storm i.e. 11.6 cfs (see attached letter) Procedure: • Installed stream gage and rain gage • Parameterized existing conditions model using VGIN landuse data, WSS soils data, and total station survey data • Calibrated the existing conditions model to storm events between 10/8/2017 to 2/10/2018 • Parameterized the proposed conditions model based on the proposed grading and outlet configuration Outputs: • Soils and landuse maps (see attachments) • Peak pond inflow rate comparison between proposed and existing conditions: Recurrence Interval Model Output Description 1YR 2YR 10YR 25YR 100YR Existing Peak Outflow (cfs) 0 0.48 7.50 12.23 35.29 Proposed Peak Outflow (cfs) 5.59 7.03 11.03 17.94 19.97 • Water quality reduction comparison: TP (lb/yr) TN (lb/yr) Existing (Detention Pond) 0.49 1.99 Proposed (Bioretention) 5.20 39.84 Existing detention pond water quality outputs (attachment 4) were calculated by CWP pursuant to DEQ Guidance Memo No 15-2005 for crediting existing BMPs. This uses Chesapeake Bay Program efficiencies and downward modifications for missing design criteria. Proposed water quality reductions were calculated pursuant to DEQ Guidance Memo No 15-2005 and used the retrofit equation for runoff reduction practices and watershed land use information calculated through a watershed analysis. Minor Hill Hydrologic Analysis July 24, 2018 Attachments: 1. Watershed soils map 2. Watershed landuse map 3. VRRM Spreadsheet 4. Existing BMP water quality reduction spreadsheet S. County Approval Letter 10/2/1979 6. PCSWMM Outputs Ecosystem Services, LLC A 1739 Allied St., Suite A, Charlottesville, VA 22903 A 540.239.1428 A www.ecosystemllc.com Page 2 of 2 w - Soil Symbol Area %Total Hazel loam 39D 0.55 7.60% Elioak loam 2713 3.99 55.11% Glenelg loam 134C 1 2.71 37.29% 1739 ALLIED STREET, SUITE A, CHARLOTTESVILLE, VIRGINIA 540.578.4296 WWW.ECOSYSTEMSERVICES.US SOIL MAP MINOR HILL ALBEMARLE COUNTY, VIRGINIA Legend Project Watershed Soils 27B 27C 34 C 39 D s 65C 95 SCALE: 1 in = 200 feet PROJECT NO: 17-0035 PM: WKM DRAWN BY: WKM SOURCE: VGIN DATE: 5/20/2018 SHEET: 1 OF 2 Landuse Area % Total Forest 0.05 0.69% Impervious 2.63 36.33% Tree 1 2.671 36.88% Turf Grass 1 1.89 26.10% 1739 ALLIED STREET, SUITE A, CHARLOTTESVILLE, VIRGINIA 540.578.4296 WWW.ECOSYSTEMSERVICES.US Site ID Site Description CWP Conversion or Existing Practice Proposed Practice if Proposed Practice if Conversion (CBP RR or Staff Enhancement Conversion Nomenclature) ST 1 137.02 1Minor Hill Townhouses lConversion I Dry Detention Pond I Constructed Wetlar IBioretention A/B soils, underdrain I RR Enter dimensions in Columns O -- U, OR water quali measurements directly in Drainage Area Urban Impervious Urban Pervious Target Storage Available Available IWS Ponding Site ID (acre) (acres) (acres) Forest (acres) %IC %Turf P (in) Rv WQv (CF) Practice Practice (Yes/No) Depth (in) Width (ft) Length (ft) 37.02 7.24 2.63 4.61 0.00 36% 64% 1.00 0.49 12751.10 37.02 ty volume from comps and/or field Column Z Combo GIS- Total Estimated Soil Top estimated Total Volume % Water Dry Filter Wet Filter Gravel Bottom Ponding Storage Site ID Surface Bottom Volume Sum for Quality Depth (in) Depth (in) Depth (in) Surface Area Volume (CF) Volume Area (SF) Surface Area (CF) Projects in Volume (field value if (CF) (SF) Series* d iff't) 3921.00 31% TP TN Pollutant Pollutant TSS Pollutant Notes Load Load Load (Ibs/yr) (Ibs/yr) (Ibs/yr) 6.93 1 56.92 1 2,246.33 Site ID Runoff Depth Captured per Impervious Acre (in) Existing Practice Efficiency Modification) - Putting an x in the box modifies the initial efficiency Absence of Absence of a Short Undersized 1: D.A.<5 Undersized 2: Pre -Retrofit Sediment micropool/protect Circuiting ac + 3" orifice OR <12- Volume<2xWQV Performance Forebay ion at outlet hr drawdown (0.5"x IC) Discount Total Phosphorus Removal (%) Existing Removal (from Table I Total Phosphorus Removal (Ibs/yr) Total Nitrogen Removal (%) 37.02 10.41 x I x I X I 1 130% 17% 10.49 14% L-S) - with Modified Efficiencies Site ID Total Nitrogen Total TSS Removal Total TSS Removal Removal (Ibs/yr) (%) (Ibs/yr) 137.02 1 1.99 1 7% 1 157.24 1 B, AUBREY HUFFMAN & ASSOCIATES, LTD. �U CIVIL ENGINEERING - LAND SURVEYING - LAND PLANNING VIRGINIA LAND COMPANY BUILDING - ROUTE 29 NORTH MAILING ADDRESS - P. O. BOX 6124 CHARLOTTESVILLE, VIRGINIA 22906 epbone 973-3326 Mr. J. Harvey Bailey Albemarle County Engineer 414 East Market Street Charlottesville, VA 22901 RE: Wynridge, Phase II final plat Dear Mr. Bailey, burr, Edwards C. L. S. President B. Aubrey Huffman C. E. Vice Presid P Oct. 2, 1979 The Albemarle County Planning Commission, at its meeting on September 27, 1979, approved the above referenced plat subject to several conditions, one of which was compliance with the Storm water Detention requirements. When the plans were drawn for a detention pond for Phase I Wynridge, most of the area for Phase II was included in the calculations. The figures used to determine the pond capacity are underlined in red on the accompanying drawing (sheet one). The second phase will also involve an additional 6.9 acres which do not drain directly into the proposed pond (marked in red on sheet 2). I have revised the calculations to adjust for additional storage as follows: Peak flow computations 110 year storm frequency) prior to development - entire basin with additional 6.9 acres c=0.2, 1=3.5 in/hr (30 min.), a=30.4 acr q=21.3 cfs after development of entire basin with an additional 6.9 acres c=0.4, 1=3.5 in/hr (30 min.), a-30,4 q=42.6 cfs As indicated in the above figures, the maximum peak discharge for the entire area should not exceed 21.3 cfs. Since the additional 6.9 acres will not be affected by the pond, they will drain at a maximum peak of 9.7 cfs; if this rate is subtracted from the total allowable rate, the remainder is the maximum rate for the pond (2193 - 9.7 = 11.6 cfs). By reducing the size of the pipe to a 15" cmp and raising the maximum pool elevation to 9.1 ft. (increasing the storage capacity to 77,896 cubic feet) the maximum theoretical discharge becomes 11.3 cfs, within the allowable limit. W/ The emergency spillway design elevation will be 477.5, the dis- charge pipe will be a 15" cmp, all other design criteria are unchan c If this information is sufficient for the requirements of the g Stormwater Detention Ordinance, please so notify N. Mason Caperton of the Albemarle County Plannin De artment. questions or su g p If you have any ggestions, please contact me at your earliest convenience. enclosure cc Mr. J Ms N. .M. Hill Mason Caperton Res ctfully, homas N. Clair Legend • Junmons Oulfalls r Storages Conduits Visible TAG ='WDT' Orifices Weirs Subcalchments e.100yr c.10yr 35 30 25 20 3 0 c m 0 ~ 15 10 5 0 Node OR a.1yr d.25yr b.2yr Sun 18 Mon 19 Tue 20 Wed Feb 2018 Date/Time �. •� j' �' ,�� •.40* .i • i d � F ,L OG so �s Y 4I • O� f • mdge Rd �• Node OF1 e.100yr c.10yr a.1yr d.25yr b.2yr 20 18 16 14 y 12 w U 3 0 c 10 m 0 8 6 4 2 0 Sun 18 Mon 19 Tue 20 We( Feb 2018 Date/Time Pond e. 100yr 5.5 5.0 4.0 ................... 3.5----------- ----- 3.0 ........ a m 0 2.5 .................... 2.0 .................... 1.5............ 1.0 ..................... 0.5 ------------ ------- 0 Sun 18 Feb 2018 Objective functions for Depth (ft) .From 2/17/2018 20:25:21 to 2/21/2018 3:29:39 (3.29 days) Exceedance threshold (ft): 0 Deficit threshold (ft): 0 ......................................:............................. Pond e. 100yr Maximum Depth(ft): 5.611 Minimum Depth(ft): 0 .............................. i Mean Depth(ft): 0.618 Duration of Exceedances(h): 71.88 Duration of Deficits(h): 0.7167..............._ ------------------------- -- Number of Exceedances: 1 Number of Deficits: 1 Volume of Exceedances(ft): 0 .....................................................................................................€----------------------------- Mon 19 Tue 20 Date/Time Wed 21 C2 b. 2yr Sun 18 Mon 19 Tue 20 Wed 21 Feb 2018 Date/Time 14 12 10 C2 b. 2yr Sun 18 Mon 19 Tue 20 Wed 21 Feb 2018 Date/Time EPA STORM WATER MANAGEMENT MODEL - VERSION 5.1 (Build 5.1.012) EXISTING -------------------------------------------------------------- WARNING O1: wet weather time step reduced to recording interval for Rain Gage 2017- 7-18 to 2018-2-9 Element Count Number of rain gages ...... 8 Number of subcatchments ... 1 Number of nodes ........... 4 Number of links ........... 5 Number of pollutants ...... 0 Number of land uses ....... 0 Raingage Summary Data Recording Name Data Source Type Interval ------------------------------------------------------------------------ 100YR NOAA Type D 9.05in 100YR NOAA Type D 9.05in INTENSITY 6 min. 10YR NOAA Type D 5.52in 10YR NOAA Type D 5.52in INTENSITY 6 min. 1YR NOAA Type D 3.02in 1YR NOAA Type D 3.02in INTENSITY 6 min. 2017-7-18 to 2018-2-9 2017-7-18 to 2018-2-9 INTENSITY 1 min. 25YR NOAA Type D 6.78in 25YR NOAA Type D 6.78in INTENSITY 6 min. 2YR NOAA Type D 3.66in 2YR NOAA Type D 3.66in INTENSITY 6 min. d._25yr d._25yr INTENSITY 6 min. e. 100yr e. 100yr INTENSITY 6 min. ******************** Subcatchment Summary Name Area Width %Impery %Slope Rain Gage Outlet ------------------------------------------------------------------------------------ ----------------------- S1 7.24 463.86 36.23 10.6750 e._100yr Pond ************ Node Summary ************ Invert Max. Ponded External Name ------------------------------------------------------------------------------- Type Elev. Depth Area Inflow J2 JUNCTION 460.90 9.25 0.0 J3 JUNCTION 459.98 15.33 0.0 OF1 OUTFALL 457.02 15.33 0.0 Pond STORAGE 463.00 10.00 0.0 Link Summary Name From Node To Node Type Length %Slope Roughness ------------------------------------------------------------------------------------ C2 J2 J3 CONDUIT 34.0 2.7036 0.0110 C3 J3 OF1 CONDUIT 56.4 5.2553 0.0400 OR1 Pond J2 ORIFICE OR2 Pond J2 ORIFICE W1 Pond J3 WEIR ********************* Cross Section Summary Full Full Hyd. Max. No. of Full Conduit Shape Depth Area Rad. Width Barrels Flow ------------------------------------------------------------------------------------ C2 CIRCULAR 1.25 1.23 0.31 1.25 1 12.55 C3 Overflow 15.33 1086.59 7.47 129.00 1 35364.44 **************** Transect Summary Transect Overflow Area: 0.0014 0.0041 0.0068 0.0097 0.0131 0.0171 0.0215 0.0260 0.0307 0.0355 0.0416 0.0487 0.0591 0.0709 0.0830 0.0952 0.1078 0.1215 0.1357 0.1508 0.1667 0.1835 0.2010 0.2190 0.2386 0.2589 0.2797 0.3014 0.3251 0.3518 0.3799 0.4088 0.4377 0.4668 0.4968 0.5276 0.5588 0.5905 0.6225 0.6546 0.6877 0.7208 0.7543 0.7885 0.8228 0.8571 0.8920 0.9277 0.9637 1.0000 Hrad: 0.0223 0.0587 0.0917 0.1219 0.1331 0.1454 0.1750 0.2033 0.2302 0.2323 0.2529 0.2581 0.1975 0.2190 0.2522 0.2846 0.2991 0.3295 0.3585 0.3854 0.3754 0.3947 0.4190 0.4225 0.4457 0.4651 0.4945 0.5059 0.4759 0.4841 0.4991 0.5331 0.5668 0.5971 0.6148 0.6341 0.6668 0.6885 0.7212 0.7360 0.7685 0.8007 0.8148 0.8471 0.8791 0.9109 0.9266 0.9425 0.9718 1.0000 Width: 0.0705 0.0743 0.0782 0.0820 0.1007 0.1194 0.1228 0.1262 0.1295 0.1492 0.1766 0.2332 0.3052 0.3306 0.3345 0.3384 0.3654 0.3837 0.3963 0.4235 0.4478 0.4696 0.4846 0.5265 0.5446 0.5674 0.5763 0.6091 0.7063 0.7545 0.7907 0.7937 0.7967 0.8044 0.8312 0.8554 0.8590 0.8777 0.8808 0.9070 0.9099 0.9127 0.9383 0.9406 0.9429 0.9451 0.9666 0.9880 0.9935 1.0000 NOTE: The summary statistics displayed in this report are based on results found at every computational time step, not just on results from each reporting time step. Analysis Options Flow Units ............... CFS Process Models: Rainfall/Runoff ........ YES RDII ................... Snowmelt ............... Groundwater ............ Flow Routing ........... Ponding Allowed ........ Water Quality .......... Infiltration Method ...... Flow Routing Method ...... Starting Date ............ Ending Date .............. Antecedent Dry Days ...... Report Time Step ......... Wet Time Step ............ Dry Time Step ............ Routing Time Step ........ Variable Time Step ....... Maximum Trials ........... Number of Threads ........ Head Tolerance ........... ************************** Runoff Quantity Continuity ************************** Total Precipitation ...... Evaporation Loss ......... Infiltration Loss ........ Surface Runoff ........... Final Storage ............ Continuity Error (%) ..... Flow Routing Continuity ************************** Dry Weather Inflow ....... Wet Weather Inflow ....... Groundwater Inflow ....... RDII Inflow .............. External Inflow .......... External Outflow ......... Flooding Loss ............ Evaporation Loss ......... Exfiltration Loss ........ Initial Stored Volume .... Final Stored Volume ...... Continuity Error (%) ..... NO NO NO YES NO NO MODIFIED_GREEN_AMPT DYNWAVE 02/18/2018 00:00:00 02/20/2018 23:54:00 0.0 00:01:00 00:01:00 00:05:00 5.00 sec YES 8 1 0.005000 ft Volume Depth acre-feet inches 5.459 9.050 0.004 0.007 1.997 3.310 3.445 5.711 0.014 0.024 -0.013 Volume Volume acre-feet --------- 10^6 gal --------- 0.000 0.000 3.444 1.122 0.000 0.000 0.000 0.000 0.000 0.000 2.654 0.865 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.790 0.257 0.001 Time -Step Critical Elements Link C2 (16.12%) Highest Flow Instability Indexes All links are stable. Routing Time Step Summary ************************* Minimum Time Step 1.28 sec Average Time Step 4.49 sec Maximum Time Step 5.00 sec Percent in Steady State 0.00 Average Iterations per Step 2.00 Percent Not Converging 0.00 *************************** Subcatchment Runoff Summary *************************** Total Peak Runoff Total Total Total Total Total Precip Runon Evap Infil Runoff Runoff Runoff Coeff Subcatchment in in in in in 10^6 gal CFS ------------------------------------------------------------------------------------ -------------------- S1 9.05 0.00 0.01 3.31 5.71 1.12 53.50 0.631 Node Depth Summary -------------------------------------------------- Average Maximum Maximum Time of Max Reported Depth Depth HGL Occurrence Max Depth Node Type Feet Feet Feet days hr:min Feet --------------------------------------------------------------------------------- J2 JUNCTION 0.12 0.98 461.88 0 12:08 0.98 J3 JUNCTION 0.07 0.78 460.76 0 12:08 0.78 OF1 OUTFALL 0.07 0.78 457.80 0 12:08 0.78 Pond STORAGE 6.67 9.79 472.79 0 12:08 9.79 Node Inflow Summary Maximum Maximum Lateral Total Flow Lateral Total Time of Max Inflow Inflow Balance Inflow Inflow Occurrence Volume Volume Error Node Type CFS CFS days hr:min 10^6 gal 10^6 gal ------------------------------------------------------------------------------------ Percent ------------- J2 JUNCTION 0.00 12.00 0 12:08 0 0.679 -0.000 J3 JUNCTION 0.00 35.35 0 12:08 0 0.865 0.003 OF1 OUTFALL 0.00 35.35 0 12:08 0 0.865 0.000 Pond STORAGE 53.50 53.50 0 12:06 1.12 1.12 0.000 Node Surcharge Summary No nodes were surcharged. ********************* Node Flooding Summary ********************* No nodes were flooded. ********************** Storage Volume Summary ********************** ------------------------------------------------------------------------------------ -------------- Average Avg Evap Exfil Maximum Max Time of Max Maximum Volume Pcnt Pcnt Pcnt Volume Pcnt Occurrence Outflow Storage Unit 1000 ft3 Full Loss Loss 1000 ft3 Full days hr:min CFS ------------------------------------------------------------------------------------ -------------- Pond 32.276 53 0 0 58.858 97 0 12:08 35.35 *********************** Outfall Loading Summary *********************** ----------------------------------------------------------- Flow Avg Max Total Freq Flow Flow Volume Outfall Node Pcnt CFS CFS 10^6 gal ----------------------------------------------------------- OF1 97.33 ----------------------------------------------------------- 1.33 35.35 0.865 System 97.33 1.33 35.35 0.865 ******************** Link Flow Summary ******************** ----------------------------------------------------------------------------- Maximum Time of Max Maximum Max/ Max/ IFlowl Occurrence IVelocl Full Full Link ----------------------------------------------------------------------------- Type CFS days hr:min ft/sec Flow Depth C2 CONDUIT 12.00 0 12:08 15.87 0.96 0.70 C3 CHANNEL 35.35 0 12:08 5.86 0.00 0.05 OR1 ORIFICE 0.00 0 12:08 OR2 ORIFICE 12.00 0 12:08 W1 WEIR 23.34 0 12:08 0.39 Flow Classification Summary Adjusted ---------- Fraction of Time in Flow Class ---------- /Actual Up Down Sub Sup Up Down Norm Inlet Conduit Length Dry Dry Dry Crit Crit Crit Crit Ltd Ctrl ------------------------------------------------------------------------------------ C2 1.00 0.01 0.00 0.00 0.00 0.99 0.00 0.00 0.02 0.00 C3 1.00 0.01 0.00 0.00 0.76 0.23 0.00 0.00 0.01 0.00 ************************* Conduit Surcharge Summary ************************* No conduits were surcharged. Analysis begun on: Wed Mar 07 15:32:46 2018 Analysis ended on: Wed Mar 07 15:32:47 2018 Total elapsed time: 00:00:01 EPA STORM WATER MANAGEMENT MODEL - VERSION 5.1 (Build 5.1.012) PROPOSED -------------------------------------------------------------- WARNING O1: wet weather time step reduced to recording interval for Rain Gage 2017- 7-18 to 2018-2-9 Element Count Number of rain gages ...... 9 Number of subcatchments ... 1 Number of nodes ........... 5 Number of links ........... 7 Number of pollutants ...... 0 Number of land uses ....... 0 Raingage Summary Data Recording Name ------------------------------------------------------------------------ Data Source Type Interval 100YR NOAA Type D 9.05in 100YR NOAA Type D 9.05in INTENSITY 6 min. 10YR NOAA Type D 5.52in 10YR NOAA Type D 5.52in INTENSITY 6 min. 1YR NOAA Type D 3.02in 1YR NOAA Type D 3.02in INTENSITY 6 min. 2017-7-18 to 2018-2-9 2017-7-18 to 2018-2-9 INTENSITY 1 min. 25YR NOAA Type D 6.78in 25YR NOAA Type D 6.78in INTENSITY 6 min. 2YR NOAA Type D 3.66in 2YR NOAA Type D 3.66in INTENSITY 6 min. c._l0yr c._l0yr INTENSITY 6 min. d._25yr d._25yr INTENSITY 6 min. e. 100yr e. 100yr INTENSITY 6 min. ******************** Subcatchment Summary Name Area Width %Impery %Slope Rain Gage Outlet ----------------------- S1 Pond Node Summary 7.24 463.86 36.23 10.6750 c. l0yr Invert Max. Ponded External Name Type Elev. Depth Area Inflow ------------------------------------------------------------------------------- J1 JUNCTION 461.10 10.90 0.0 J2 JUNCTION 460.90 9.25 0.0 J3 JUNCTION 459.98 15.33 0.0 OF1 OUTFALL 457.02 15.33 0.0 Pond STORAGE 464.60 8.40 0.0 Link Summary Name From Node To Node Type Length %Slope Roughness ------------------------------------------------------------------------------------ C1 J1 J2 CONDUIT 20.0 1.0001 0.0130 C2 J2 J3 CONDUIT 34.0 2.7036 0.0110 C3 J3 OF1 CONDUIT 56.4 5.2553 0.0400 OR1 Pond J1 ORIFICE OR2 Pond J2 ORIFICE OR3 Pond Jl ORIFICE W1 Pond J3 WEIR Cross Section Summary Full Full Hyd. Max. No. of Full Conduit Shape Depth Area Rad. Width Barrels Flow ------------------------------------------------------------------------------------ C1 CIRCULAR 1.00 0.79 0.25 1.00 1 3.56 C2 CIRCULAR 1.25 1.23 0.31 1.25 1 12.55 C3 Overflow 15.33 1086.59 7.47 129.00 1 35364.44 **************** Transect Summary **************** Transect Overflow Area: 0.0014 0.0041 0.0068 0.0097 0.0131 0.0171 0.0215 0.0260 0.0307 0.0355 0.0416 0.0487 0.0591 0.0709 0.0830 0.0952 0.1078 0.1215 0.1357 0.1508 0.1667 0.1835 0.2010 0.2190 0.2386 0.2589 0.2797 0.3014 0.3251 0.3518 0.3799 0.4088 0.4377 0.4668 0.4968 0.5276 0.5588 0.5905 0.6225 0.6546 0.6877 0.7208 0.7543 0.7885 0.8228 0.8571 0.8920 0.9277 0.9637 1.0000 Hrad: 0.0223 0.0587 0.0917 0.1219 0.1331 0.1454 0.1750 0.2033 0.2302 0.2323 0.2529 0.2581 0.1975 0.2190 0.2522 0.2846 0.2991 0.3295 0.3585 0.3854 0.3754 0.3947 0.4190 0.4225 0.4457 0.4651 0.4945 0.5059 0.4759 0.4841 0.4991 0.5331 0.5668 0.5971 0.6148 0.6341 0.6668 0.6885 0.7212 0.7360 0.7685 0.8007 0.8148 0.8471 0.8791 0.9109 0.9266 0.9425 0.9718 1.0000 Width: 0.0705 0.0743 0.0782 0.0820 0.1007 0.1194 0.1228 0.1262 0.1295 0.1492 0.1766 0.2332 0.3052 0.3306 0.3345 0.3384 0.3654 0.3837 0.3963 0.4235 0.4478 0.4696 0.4846 0.5265 0.5446 0.5674 0.5763 0.6091 0.7063 0.7545 0.7907 0.7937 0.7967 0.8044 0.8312 0.8554 0.8590 0.8777 0.8808 0.9070 0.9099 0.9127 0.9383 0.9406 0.9429 0.9451 0.9666 0.9880 0.9935 1.0000 NOTE: The summary statistics displayed in this report are based on results found at every computational time step, not just on results from each reporting time step. Analysis Options **************** Flow Units ............... Process Models: Rainfall/Runoff ........ RDII ................... Snowmelt ............... Groundwater ............ Flow Routing ........... Ponding Allowed ........ Water Quality .......... Infiltration Method ...... Flow Routing Method ...... Starting Date ............ Ending Date .............. Antecedent Dry Days ...... Report Time Step ......... Wet Time Step ............ Dry Time Step ............ Routing Time Step ........ Variable Time Step ....... Maximum Trials ........... Number of Threads ........ Head Tolerance ........... ************************** Runoff Quantity Continuity ************************** Total Precipitation ...... Evaporation Loss ......... Infiltration Loss ........ Surface Runoff ........... Final Storage ............ Continuity Error (%) ..... Flow Routing Continuity Dry Weather Inflow ....... Wet Weather Inflow ....... Groundwater Inflow ....... RDII Inflow .............. External Inflow .......... CFS YES NO NO NO YES NO NO MODIFIED GREEN AMPT DYNWAVE 02/18/2018 00:00:00 02/20/2018 23:54:00 0.0 00:01:00 00:01:00 00:05:00 5.00 sec YES 8 1 0.005000 ft Volume acre-feet 3.330 0.004 1.515 1.797 0.014 -0.012 Volume acre-feet 0.000 1.797 0.000 0.000 0.000 Depth inches 5.520 0.007 2.511 2.979 0.024 Volume 10^6 gal 0.000 0.586 0.000 0.000 0.000 External Outflow ......... Flooding Loss ............ Evaporation Loss ......... Exfiltration Loss ........ Initial Stored Volume .... Final Stored Volume ...... Continuity Error (%) ..... *************************** Time -Step Critical Elements Link Cl (44.43%) Highest Flow Instability Indexes All links are stable. ************************* Routing Time Step Summary ************************* Minimum Time Step Average Time Step Maximum Time Step Percent in Steady State Average Iterations per Step Percent Not Converging *************************** Subcatchment Runoff Summary *************************** Total Peak Runoff 1.757 0.000 0.000 0.000 0.000 0.040 0.000 0.68 sec 3.76 sec 5.00 sec -0.00 2.02 0.22 0.573 0.000 0.000 0.000 0.000 0.013 Total Total Total Total Total Precip Runon Evap Infil Runoff Runoff Runoff Coeff Subcatchment in in in in in 10^6 gal CFS ------------------------------------------------------------------------------------ -------------------- S1 5.52 0.00 0.01 2.51 2.98 0.59 28.00 0.540 ****************** Node Depth Summary ****************** -------------------------------------------------- Average Maximum Maximum Time of Max Reported Depth Depth HGL Occurrence Max Depth Node Type Feet Feet Feet days hr:min Feet --------------------------------------------------------------------------------- J1 JUNCTION 0.28 2.66 463.76 0 12:19 2.66 J2 JUNCTION 0.14 0.91 461.81 0 12:19 0.91 J3 JUNCTION 0.08 0.45 460.43 0 12:19 0.45 OF1 OUTFALL 0.08 0.45 457.47 0 12:19 0.45 Pond STORAGE 0.72 3.30 467.90 0 12:19 3.30 ******************* Node Inflow Summary ******************* ------------------------------------------------------------------------------------ ------------- Maximum Maximum Lateral Total Flow Lateral Total Time of Max Inflow Inflow Balance Inflow Inflow Occurrence Volume Volume Error Node Type CFS CFS days hr:min 10^6 gal 10^6 gal ------------------------------------------------------------------------------------ Percent ------------- J1 JUNCTION 0.00 11.03 0 12:19 0 0.573 -0.001 J2 JUNCTION 0.00 11.03 0 12:19 0 0.573 0.003 J3 JUNCTION 0.00 11.03 0 12:19 0 0.573 -0.001 OF1 OUTFALL 0.00 11.03 0 12:19 0 0.573 0.000 Pond STORAGE 28.00 28.00 0 12:06 0.586 0.586 0.000 ********************** Node Surcharge Summary No nodes were surcharged. ********************* Node Flooding Summary ********************* No nodes were flooded. Storage Volume Summary ------------------------------------------------------------------------------------ -------------- Average Avg Evap Exfil Maximum Max Time of Max Maximum Volume Pcnt Pcnt Pcnt Volume Pcnt Occurrence Outflow Storage Unit 1000 ft3 Full Loss Loss 1000 ft3 Full days hr:min CFS ------------------------------------------------------------------------------------ -------------- Pond 2.800 5 0 0 16.545 28 0 12:19 11.03 Outfall Loading Summary ----------------------------------------------------------- Flow Avg Max Total Freq Flow Flow Volume Outfall Node Pcnt CFS CFS 10^6 gal ----------------------------------------------------------- OF1 50.26 2.04 11.03 0.573 ----------------------------------------------------------- System 50.26 2.04 11.03 0.573 Link Flow Summary ----------------------------------------------------------------------------- Maximum Time of Max Maximum Max/ Max/ IFlowl Occurrence IVelocl Full Full Link ----------------------------------------------------------------------------- Type CFS days hr:min ft/sec Flow Depth C1 CONDUIT 11.03 0 12:19 14.28 3.10 0.95 C2 CONDUIT 11.03 0 12:19 16.12 0.88 0.55 C3 CHANNEL 11.03 0 12:19 3.82 0.00 0.03 OR1 ORIFICE 11.03 0 12:19 1.00 OR2 ORIFICE 0.00 0 00:00 OR3 ORIFICE 0.00 0 00:00 W1 WEIR 0.00 0 00:00 0.00 *************************** Flow Classification Summary *************************** Adjusted ---------- Fraction of Time in Flow Class ---------- /Actual Up Down Sub Sup Up Down Norm Inlet Conduit Length Dry Dry Dry Crit Crit Crit Crit Ltd Ctrl ------------------------------------------------------------------------------------ C1 1.00 0.04 0.00 0.00 0.45 0.51 0.00 0.00 0.64 0.00 C2 1.00 0.04 0.00 0.00 0.37 0.59 0.00 0.00 0.49 0.00 C3 1.00 0.31 0.00 0.00 0.40 0.29 0.00 0.00 0.57 0.00 ************************* Conduit Surcharge Summary ************************* ---------------------------------------------------------------------------- Hours Hours --------- Hours Full -------- Above Full Capacity Conduit Both Ends Upstream Dnstream Normal Flow Limited ---------------------------------------------------------------------------- C1 0.01 1.23 0.01 1.57 0.01 Analysis begun on: Wed Mar 07 16:26:18 2018 Analysis ended on: Wed Mar 07 16:26:19 2018 Total elapsed time: 00:00:01