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From page 31... ... Annex A Volume Performance Tool Technical Documentation 1 Introduction and Purpose ..................................................................................................................... 1 2 Model Overview ..................................................................................................................................... Read the entire page →
From page 32... ... 7.4.1 Hypothesis ................................................................................................................................................ 26 7.4.2 Analysis .................................................................................................................................................... Read the entire page →
From page 33... ... 1 Introduction and Purpose The performance of volume reduction approaches (VRAs) is a function of many factors, including local climate and hydrology, storage volume, VRA design (i.e., footprint, depth, and discharge rates) Read the entire page →
From page 34... ... macro-enabled Excel spreadsheet that contains a "lookup database" – a directory of data files that contain summary statistics from the long term hydrologic and hydraulic model runs completed as part of developing the tool. The user navigates through the tool using navigation buttons or tabs, populating information about the specific project and VRA scenario and viewing estimated volume performance results. Read the entire page →
From page 35... ... Figure 1. Schematic Representation of VRAs for Purpose of Capture Efficiency and Volume Reduction Analysis 3.2 Capture Efficiency Capture efficiency (or "percent capture") Read the entire page →
From page 36... ... By isolating these two most important predictive variables, a limited number of continuous simulation model runs and associated results can be used to describe the expected long term performance of a wide range of VRA types and configurations. For example, the results of a long term model simulation for a 0.75-inch normalized storage depth with 24-hour drawdown would be representative of a wide range of different VRA configurations. Read the entire page →
From page 37... ... 3.4 Total Volume Reduction Performance The total volume reduction performance was expressed in terms of: • Watershed relative volume reduction – the relative reduction in surface discharge volume compared to the same tributary area without controls, calculated as: Watershed relative volume reduction = Σ (% Cap) Read the entire page →
From page 38... ... 2. For the first compartment, the tool computes the equivalent storm depth (i.e., the storm depth that would be required to produce runoff from the watershed equal to the storage volume of the compartment) Read the entire page →
From page 39... ... Figure 2: Example application of method for incorporating multi-compartment VRAs (hypothetical location) 3.6 Approach for Localizing Model Estimates The tool was pre-packaged with lookup databases containing model results for 344 climate divisions (represented by a single point location precipitation/weather gage for each division) Read the entire page →
From page 40... ... the relative magnitudes of the 85th percentile, 24-hour storm event at each point, then similarity in long term capture efficiency and volume reduction appear to be maintained. For example the capture efficiency would be expected to be similar for the following two points because their design volume as a fraction of the 85th percentile, 24-hour runoff volumes are the same: Point A: Runoff volume from 85th percentile, 24-hour storm = 3,200 cu-ft Actual VRA sized for 2,000 cu-ft Design volume as fraction of 85th percentile, 24-hour runoff volume = 2,000/3,200 = 0.625 Point B: Runoff volume from 85th percentile, 24-hour storm = 5,000 cu-ft Actual VRA sized for 3,125 cu-ft Design volume as fraction of 85th percentile, 24-hour runoff volume = 3,125/5,000 = 0.625 In other words, in order to achieve the same capture efficiency at Point B as Point A, the actual VRA size would need to be scaled up by the ratio of the 85th percentile, 24-hour storm depths. Read the entire page →
From page 41... ... For example: 1. The 85th percentile, 24-hour depth at the climate division gage that is used to represent the overall division in the modeling is 0.95 inches. Read the entire page →
From page 42... ... • Dispersion runs: Dispersion runs were used to represent VRA types that cannot be simply divided into compartments because water is dispersed in a thin layer and is acted upon by both infiltration and ET processes. The template model setup developed for these runs included a tributary subcatchment draining to two broad, shallow storage units in series (area varied between runs to represent different proportions of pervious area receiving dispersion) Read the entire page →
From page 43... ... Figure 3. NCDC Climate Divisions 4.2.2 Evapotranspiration Data Reference potential evapotranspiration data were obtained from the United States Geologic Service Oak Ridge National Laboratory (Vogel and Sankarasubramania 2005) Read the entire page →
From page 44... ... 4.2.3 SWMM Hydrologic Parameters Table 1 contains the parameters that were used in the SWMM simulation of rainfall-runoff. Table 1. Read the entire page →
From page 45... ... SWMM Runoff Parameters Units Values Source/Rationale Pervious Manning's n 0.15 McCuen et al. 1996 – Based on short grass Infiltration Model NA Green-Ampt Based on availability of parameters and supporting documentation. Read the entire page →
From page 46... ... NCHRP 25-41 Guidance for Achieving Volume Reduction of Highway Runoff in Urban Areas 4.2.5 Drawdown Increments For compartments of VRAs that can be approximated by a consistent drawdown time (i.e., drained by infiltration or by a surface discharge outlet) , model increments were defined by 10 standard drawdown times that are relevant for most VRAs (hours) Read the entire page →
From page 47... ... NCHRP 25-41 Guidance for Achieving Volume Reduction of Highway Runoff in Urban Areas Table 3. Increments of Input Parameters for Dispersion Runs Ratio of Impervious Area Draining to VRA to Pervious Area Receiving Dispersion Soil Properties of Underlying Soils Below Amended Soil in Dispersion Area Depth of Soil Amendment or Decompaction, inches Saturated Hydraulic Conductivity, in/hr Initial Moisture Deficit, inches/ inch Suction Head, inches 50 0.00 0.16 11.4 0 20 0.01 0.16 11.4 3 10 0.05 0.21 8.7 6 5 0.10 0.21 8.7 12 2.5 0.20 0.29 6.7 24 1.0 0.50 0.29 6.7 0.5 1.00 0.36 2.4 0.25 2.00 0.36 2.4 4.2.8 Summary of Supporting Model Runs Table 4 provides a summary of the supporting model runs that were executed to provide the back-end database to support the tool. Read the entire page →
From page 48... ... NCHRP 25-41 Guidance for Achieving Volume Reduction of Highway Runoff in Urban Areas Parameter Number of Increments Dispersion Model Runs Climate Divisions 344 Ratio of Impervious to Pervious 8 Soil Properties below Amended Soil 8 Amended Soil Depth 5 Total – Dispersion Model Runs 110,080 Total Number of Model Runs 168,560 Model runs were executed using macros that automate the development of SWMM files and execute these files in batch simulation model. Computationally it would have been possible to conduct more runs, however the size of the lookup database would increase and potentially create excessive file sizes for the Tool. Read the entire page →
From page 49... ... NCHRP 25-41 Guidance for Achieving Volume Reduction of Highway Runoff in Urban Areas o Estimate the volume of each compartment based on the design parameters specified by the user and the default parameter assumptions. o Normalize the volume of each compartment in terms of the runoff volume produced from an equivalent storm depth over the tributary area. Read the entire page →
From page 50... ... NCHRP 25-41 Guidance for Achieving Volume Reduction of Highway Runoff in Urban Areas • A sensitivity analysis interface allows the user to specify a high and low bound for up to three key parameters per VRA. An underlying sensitivity analysis algorithm is then executed to cycle through the tool calculations for the high and low bounds of each specified sensitivity parameter, holding the other specified parameters fixed at their original assigned value. Read the entire page →
From page 51... ... NCHRP 25-41 Guidance for Achieving Volume Reduction of Highway Runoff in Urban Areas 5. Model scenarios were based on discrete increments of input parameters, and interpolation is required between entries in the lookup database. Read the entire page →
From page 52... ... NCHRP 25-41 Guidance for Achieving Volume Reduction of Highway Runoff in Urban Areas Overall, these simplifying assumptions are expected to have a relatively minor impact on the model results and are considered to be reliable for planning level estimates of volume reduction performance. As with any modeling tool, a major source of error can arise from the user entering erroneous input parameters or entering input parameters that do not reflect realistic design scenarios. Read the entire page →
From page 53... ... NCHRP 25-41 Guidance for Achieving Volume Reduction of Highway Runoff in Urban Areas Figure 4. Precipitation gages used for testing the reliability of simplifying assumptions (with NCDC climate division boundaries shown) Read the entire page →
From page 54... ... NCHRP 25-41 Guidance for Achieving Volume Reduction of Highway Runoff in Urban Areas Runoff Coefficient = m × imp + b Where: imp = impervious cover as a fraction from 0 to 1; m and b are coefficients ranging from 0 to 1. Different coefficients were developed for different soil types. Read the entire page →
From page 55... ... NCHRP 25-41 Guidance for Achieving Volume Reduction of Highway Runoff in Urban Areas 7.1.3 Summary of Findings Based the summary presented in Table 5 and evaluation of individual runs (not reported) , average ranges of capture efficiency differences observed in the analysis for Washington D.C. Read the entire page →
From page 56... ... NCHRP 25-41 Guidance for Achieving Volume Reduction of Highway Runoff in Urban Areas Table 6. Analysis Performed to Test Simplifying Assumption 2 Climate Division Coop Id Station Name 85th Percentile (in) Read the entire page →
From page 57... ... NCHRP 25-41 Guidance for Achieving Volume Reduction of Highway Runoff in Urban Areas from the first compartment (or fills when the capacity of the first is exceeded) Read the entire page →
From page 58... ... NCHRP 25-41 Guidance for Achieving Volume Reduction of Highway Runoff in Urban Areas 7.3.3 Summary of Findings The analysis performed to test the graphical method for two typical VRA scenarios supports this simplifying assumption and validates the usage of the graphical approach presented Section 3.5. The relative error produced using this approach appears to be much smaller than the uncertainty in model inputs (based on the summary in Table 8 and evaluation of individual runs, not reported) Read the entire page →
From page 59... ... NCHRP 25-41 Guidance for Achieving Volume Reduction of Highway Runoff in Urban Areas 7.4.3 Summary of Findings Simulations with monthly normal ET data generated slightly smaller runoff quantities and slightly greater capture percentages than simulations with daily ET data. However, considering the small differences in predicted estimates and the simplicity offered by the use of monthly normal ET data, monthly normal data was considered most appropriate for this analysis. Read the entire page →
From page 60... ... NCHRP 25-41 Guidance for Achieving Volume Reduction of Highway Runoff in Urban Areas 9 Precipitation Gages Supported by Tool State Climate Division Number Climate Division Name Selected COOP Station COOP Station Name County Elevation, MSL Calculated 85th Percentile, 24-hour Storm Depth Calculated 95th Percentile, 24-hour Storm Depth Calculated Average Annual Precipitation Depth, inches AL 1 NORTHERN VALLEY 014064 HUNTSVILLE INTL AP MADISON 624 1.24 2.00 54.9 AL 2 APPALACHIAN MOUNTAIN 010831 BIRMINGHAM AP ASOS JEFFERSON 615 1.20 1.93 45.1 AL 3 UPPER PLAINS 010063 ADDISON WINSTON 818 1.30 2.10 51.2 AL 4 EASTERN VALLEY 014209 JACKSONVILLE CALHOUN 688 1.20 1.92 45.6 AL 5 PIEDMONT PLATEAU 012124 DADEVILLE 2 TALLAPOOSA 733 1.30 2.00 51.7 AL 6 PRAIRIE 015550 MONTGOMERY AP ASOS MONTGOMERY 202 1.25 2.01 51.0 AL 7 COASTAL PLAIN 010140 ALBERTA WILCOX 175 1.40 2.20 55.2 AL 8 GULF 015478 MOBILE REGIONAL AP MOBILE 215 1.45 2.42 58.6 AR 1 NORTHWEST 032356 EUREKA SPRINGS 3 WNW CARROLL 1,420 1.20 1.91 43.2 AR 2 NORTH CENTRAL 032794 GILBERT SEARCY 620 1.18 1.95 42.9 AR 3 NORTHEAST 030458 BATESVILLE LVSTK INDEPENDENCE 571 1.30 2.10 45.9 AR 4 WEST CENTRAL 032574 FT SMITH RGNL AP SEBASTIAN 449 1.20 1.92 42.3 AR 5 CENTRAL 034248 LITTLE ROCK ADAMS FLD PULASKI 258 1.28 2.10 29.3 AR 6 EAST CENTRAL 036920 STUTTGART 9 ESE ARKANSAS 198 1.30 2.20 47.8 AR 7 SOUTHWEST 032810 GILLHAM DAM POLK 520 1.50 2.40 54.3 AR 8 SOUTH CENTRAL 030220 ARKADELPHIA 2 N CLARK 196 1.44 2.30 52.5 AR 9 SOUTHEAST 035754 PINE BLUFF JEFFERSON 215 1.40 2.20 49.3 AZ 1 NORTHWEST 024645 KINGMAN #2 MOHAVE 3,539 0.80 1.20 9.0 AZ 2 NORTHEAST 029439 WINSLOW AP NAVAJO 4,886 0.48 0.75 7.3 AZ 3 NORTH CENTRAL 020487 ASH FORK 3 YAVAPAI 5,075 0.69 1.10 12.3 AZ 4 EAST CENTRAL 026323 PAYSON GILA 4,850 0.90 1.50 19.3 A-28 Read the entire page →
From page 61... ... NCHRP 25-41 Guidance for Achieving Volume Reduction of Highway Runoff in Urban Areas State Climate Division Number Climate Division Name Selected COOP Station COOP Station Name County Elevation, MSL Calculated 85th Percentile, 24-hour Storm Depth Calculated 95th Percentile, 24-hour Storm Depth Calculated Average Annual Precipitation Depth, inches AZ 5 SOUTHWEST 029660 YUMA WSO AP YUMA 206 0.58 1.11 2.9 AZ 6 SOUTH CENTRAL 026481 PHOENIX AP MARICOPA 1,107 0.67 1.02 7.2 AZ 7 SOUTHEAST 028820 TUCSON INTL AP PIMA 2,549 0.66 1.10 11.3 CA 1 NORTH COAST DRAINAGE 042910 EUREKA WFO WOODLEY IS HUMBOLDT 20 0.88 1.37 39.2 CA 2 SACRAMENTO DRNG. Read the entire page →
From page 62... ... NCHRP 25-41 Guidance for Achieving Volume Reduction of Highway Runoff in Urban Areas State Climate Division Number Climate Division Name Selected COOP Station COOP Station Name County Elevation, MSL Calculated 85th Percentile, 24-hour Storm Depth Calculated 95th Percentile, 24-hour Storm Depth Calculated Average Annual Precipitation Depth, inches FL 6 LOWER EAST COAST 085663 MIAMI INTL AP MIAMI-DADE 29 1.28 2.20 58.9 GA 1 NORTHWEST 092485 DALLAS 7 NE PAULDING 1,100 1.20 1.98 49.3 GA 2 NORTH CENTRAL 090451 ATLANTA/MUN., GA. Read the entire page →
From page 63... ... NCHRP 25-41 Guidance for Achieving Volume Reduction of Highway Runoff in Urban Areas State Climate Division Number Climate Division Name Selected COOP Station COOP Station Name County Elevation, MSL Calculated 85th Percentile, 24-hour Storm Depth Calculated 95th Percentile, 24-hour Storm Depth Calculated Average Annual Precipitation Depth, inches ID 8 NORTHEASTERN VALLEYS 105169 LEADORE LEMHI 6,000 0.40 0.60 8.5 ID 9 UPPER SNAKE RIVER PLAINS 107211 POCATELLO RGNL AP POWER 4,478 0.42 0.63 11.2 ID 10 EASTERN HIGHLANDS 104456 IDAHO FALLS 16 SE BONNEVILLE 5,828 0.50 0.70 16.4 IL 1 NORTHWEST 115751 MOLINE WSO AP ROCK ISLAND 592 0.96 1.56 36.9 IL 2 NORTHEAST 111577 CHICAGO MIDWAY AP 3SW COOK 620 0.90 1.50 36.4 IL 3 WEST 110082 ALEXIS 1 SW WARREN 680 0.97 1.60 33.2 IL 4 CENTRAL 116711 PEORIA GTR PEORIA RGNL PEORIA 650 0.93 1.47 35.3 IL 5 EAST 114198 HOOPESTON 1NE VERMILION 710 0.90 1.50 36.1 IL 6 WEST SOUTHWEST 118179 SPRINGFIELD LINCOLN AP SANGAMON 594 0.90 1.47 34.9 IL 7 EAST SOUTHEAST 116159 NEWTON 6 SSE JASPER 510 1.00 1.60 39.7 IL 8 SOUTHWEST 115983 MURPHYSBORO 2 SW JACKSON 550 1.10 1.74 43.9 IL 9 SOUTHEAST 112353 DIXON SPRINGS AG CTR POPE 527 1.15 1.82 45.8 IN 1 NORTHWEST 125535 MEDARYVILLE 5 N PULASKI 695 0.90 1.50 36.2 IN 2 NORTH CENTRAL 128187 SOUTH BEND AP ST. Read the entire page →
From page 64... ... NCHRP 25-41 Guidance for Achieving Volume Reduction of Highway Runoff in Urban Areas State Climate Division Number Climate Division Name Selected COOP Station COOP Station Name County Elevation, MSL Calculated 85th Percentile, 24-hour Storm Depth Calculated 95th Percentile, 24-hour Storm Depth Calculated Average Annual Precipitation Depth, inches KS 6 EAST CENTRAL 148167 TOPEKA BILLARD MUNI AP SHAWNEE 881 1.07 1.78 34.7 KS 7 SOUTHWEST 142164 DODGE CITY RGNL AP FORD 2,582 0.86 1.44 20.5 KS 8 SOUTH CENTRAL 148830 WICHITA MID-CONTINENT SEDGWICK 1,321 1.10 1.76 30.2 KS 9 SOUTHEAST 141351 CASSODAY 2SW BUTLER 1,440 1.15 1.80 32.2 KY 1 WESTERN 151631 CLINTON 4 S HICKMAN 350 1.20 1.90 46.5 KY 2 CENTRAL 154954 LOUISVILLE INTL AP JEFFERSON 488 0.95 1.51 43.9 KY 3 BLUE GRASS 154746 LEXINGTON BLUEGRASS AP FAYETTE 980 0.94 1.50 45.5 KY 4 EASTERN 151080 BUCKHORN LAKE PERRY 780 0.90 1.44 45.8 LA 1 NORTHWEST 168440 SHREVEPORT AP CADDO 254 1.32 2.16 42.5 LA 2 NORTH CENTRAL 169803 WINNFIELD 3 N WINN 160 1.40 2.30 56.0 LA 3 NORTHEAST 169806 WINNSBORO 5 SSE FRANKLIN 80 1.46 2.30 54.0 LA 4 WEST CENTRAL 165266 LEESVILLE VERNON 28 1.40 2.40 52.8 LA 5 CENTRAL 169357 VIDALIA #2 CONCORDIA 60 1.50 2.55 54.5 LA 6 EAST CENTRAL 160549 BATON ROUGE METRO AP EAST BATON ROUGE 64 1.36 2.30 57.7 LA 7 SOUTHWEST 165078 LAKE CHARLES AP CALCASIEU 9 1.47 2.55 55.6 LA 8 SOUTH CENTRAL 165021 LAFAYETTE LAFAYETTE 25 1.50 2.70 60.3 LA 9 SOUTHEAST 166660 NEW ORLEANS AP JEFFERSON 4 1.44 2.40 61.3 MA 1 WESTERN 193985 KNIGHTVILLE DAM HAMPSHIRE 630 1.00 1.68 44.5 MA 2 CENTRAL 190736 BLUE HILL NORFOLK 625 1.08 1.75 50.2 MA 3 COASTAL 190770 BOSTON SUFFOLK 12 0.96 1.57 43.1 MD 1 SOUTHEASTERN SHORE 188005 SALISBURY FAA AP WICOMICO 48 0.92 1.86 44.1 MD 2 CENTRAL EASTERN SHORE 183090 FEDERALSBURG CAROLINE 20 1.10 1.90 43.8 MD 3 LOWER SOUTHERN 186915 PATUXENT RIVER ST. Read the entire page →
From page 65... ... NCHRP 25-41 Guidance for Achieving Volume Reduction of Highway Runoff in Urban Areas State Climate Division Number Climate Division Name Selected COOP Station COOP Station Name County Elevation, MSL Calculated 85th Percentile, 24-hour Storm Depth Calculated 95th Percentile, 24-hour Storm Depth Calculated Average Annual Precipitation Depth, inches MD 8 ALLEGHENY PLATEAU 188315 SINES DEEP CREEK GARRETT 2,040 0.74 1.16 46.9 ME 1 NORTHERN 171175 CARIBOU WFO AROOSTOOK 624 0.70 1.06 37.0 ME 2 SOUTHERN INTERIOR 178641 SWANS FALLS OXFORD 400 1.00 1.60 43.1 ME 3 COASTAL 176905 PORTLAND JETPORT CUMBERLAND 45 0.97 1.62 43.7 MI 1 WEST UPPER 204090 IRON MT KINGSFORD WWTP DICKINSON 1,071 0.79 1.20 28.3 MI 2 EAST UPPER 207366 SAULT STE MARIE SNDRSN CHIPPEWA 722 0.62 1.02 32.6 MI 3 NORTHWEST 200662 BELLAIRE ANTRIM 625 0.70 1.10 31.2 MI 4 NORTHEAST LOWER 200164 ALPENA CO RGNL AP ALPENA 684 0.66 1.04 27.7 MI 5 WEST CENTRAL LOWER 205712 MUSKEGON CO AP MUSKEGON 625 0.71 1.15 32.1 MI 6 CENTRAL LOWER 203170 GLADWIN GLADWIN 775 0.80 1.40 18.3 MI 7 EAST CENTRAL LOWER 203580 HARBOR BEACH HURON 600 0.70 1.10 29.5 MI 8 SOUTHWEST LOWER 203333 GERALD R FORD INTL AP KENT 803 0.82 1.33 35.8 MI 9 SOUTH CENTRAL LOWER 204155 JACKSON 3N JACKSON 950 0.80 1.26 30.6 MI 10 SOUTHEAST LOWER 202846 FLINT BISHOP INTL AP GENESEE 770 0.71 1.16 26.2 MN 1 NORTHWEST 218235 THIEF LAKE REFUGE MARSHALL 1,142 0.80 1.30 23.2 MN 2 NORTH CENTRAL 214026 INTERNATIONAL FALLS AP KOOCHICHING 1,183 0.68 1.14 24.3 MN 3 NORTHEAST 212248 DULUTH INTL AP ST. Read the entire page →
From page 66... ... NCHRP 25-41 Guidance for Achieving Volume Reduction of Highway Runoff in Urban Areas State Climate Division Number Climate Division Name Selected COOP Station COOP Station Name County Elevation, MSL Calculated 85th Percentile, 24-hour Storm Depth Calculated 95th Percentile, 24-hour Storm Depth Calculated Average Annual Precipitation Depth, inches MO 4 WEST OZARKS 237976 SPRINGFIELD WSO AP GREENE 1,259 1.10 1.78 42.0 MO 5 EAST OZARKS 238620 VIENNA 2 WNW MARIES 770 1.11 1.74 41.3 MO 6 BOOTHEEL 233999 HORNERSVILLE DUNKLIN 250 1.25 2.07 46.4 MS 1 UPPER DELTA 221743 CLEVELAND 3 N BOLIVAR 140 1.40 2.30 50.4 MS 2 NORTH CENTRAL 227815 SARDIS DAM PANOLA 303 1.32 2.16 53.9 MS 3 NORTHEAST 229003 TUPELO RGNL AP LEE 361 1.30 2.13 54.4 MS 4 LOWER DELTA 228445 STONEVILLE EXP STN WASHINGTON 127 1.40 2.10 50.0 MS 5 CENTRAL 225062 LEXINGTON HOLMES 285 1.40 2.23 54.1 MS 6 EAST CENTRAL 228374 STATE UNIV OKTIBBEHA 185 1.30 2.11 51.8 MS 7 SOUTHWEST 227714 RUTH 1 SE LINCOLN 443 1.43 2.35 56.4 MS 8 SOUTH CENTRAL 227220 PURVIS 2N LAMAR 378 1.40 2.30 59.8 MS 9 SOUTHEAST 225776 MERIDIAN AP LAUDERDALE 294 1.30 2.12 55.2 MS 10 COASTAL 227840 SAUCIER EXP FOREST HARRISON 229 1.50 2.50 66.9 MT 1 WESTERN 245745 MISSOULA INTL AP MISSOULA 3,192 0.41 0.64 13.2 MT 2 SOUTHWESTERN 241309 BUTTE 8 S SILVER BOW 5,700 0.50 0.80 14.8 MT 3 NORTH CENTRAL 241737 CHOTEAU TETON 3,845 0.63 1.00 10.6 MT 4 CENTRAL 244055 HELENA AP ASOS LEWIS AND CLARK 3,828 0.45 0.73 11.0 MT 5 SOUTH CENTRAL 240807 BILLINGS INTL AP YELLOWSTONE 3,581 0.51 0.85 13.7 MT 6 NORTHEASTERN 241088 BREDETTE ROOSEVELT 2,638 0.65 1.02 12.3 MT 7 SOUTHEASTERN 248169 TERRY 21 NNW PRAIRIE 3,142 0.63 1.06 13.9 NC 1 SOUTHERN MOUNTAINS 310301 ASHEVILLE BUNCOMBE 2,238 0.82 1.37 37.8 NC 2 NORTHERN MOUNTAINS 319675 YADKINVILLE 6 E YADKIN 875 1.00 1.63 43.1 NC 3 NORTHERN PIEDMONT 313630 GREENSBORO AP GUILFORD 890 0.98 1.56 42.1 NC 4 CENTRAL PIEDMONT 317069 RALEIGH AP WAKE 416 0.99 1.57 42.2 NC 5 SOUTHERN PIEDMONT 311690 CHARLOTTE DOUGLAS AP MECKLENBURG 728 1.01 1.67 42.4 NC 6 SOUTHERN COASTAL PLAIN 319457 WILMINGTON INTL AP NEW HANOVER 33 1.24 2.19 54.7 A-34 Read the entire page →
From page 67... ... NCHRP 25-41 Guidance for Achieving Volume Reduction of Highway Runoff in Urban Areas State Climate Division Number Climate Division Name Selected COOP Station COOP Station Name County Elevation, MSL Calculated 85th Percentile, 24-hour Storm Depth Calculated 95th Percentile, 24-hour Storm Depth Calculated Average Annual Precipitation Depth, inches NC 7 CENTRAL COASTAL PLAIN 319476 WILSON 3 SW WILSON 110 1.10 1.74 38.5 NC 8 NORTHERN COASTAL PLAIN 311458 CAPE HATTERAS AP DARE 11 1.26 2.16 55.8 ND 1 NORTHWEST 329425 WILLISTON SLOULIN FLD WILLIAMS 1,902 0.57 1.02 13.4 ND 2 NORTH CENTRAL 320492 BALFOUR 3 SW MCHENRY 1,615 0.76 1.30 15.9 ND 3 NORTHEAST 321435 CAVALIER 7NW PEMBINA 890 0.90 1.50 19.3 ND 4 WEST CENTRAL 327585 RIVERDALE MCLEAN 1,977 0.80 1.35 16.6 ND 5 CENTRAL 322018 DAWSON KIDDER 1,730 0.79 1.38 17.5 ND 6 EAST CENTRAL 322859 FARGO HECTOR INTL AP CASS 900 0.74 1.30 20.0 ND 7 SOUTHWEST 327530 RICHARDTON ABBEY STARK 2,470 0.70 1.21 17.0 ND 8 SOUTH CENTRAL 320819 BISMARCK MUNI AP BURLEIGH 1,651 0.66 1.12 15.9 ND 9 SOUTHEAST 320382 ASHLEY MCINTOSH 2,014 0.80 1.40 17.6 NE 1 PANHANDLE 257665 SCOTTSBLUFF AP SCOTTS BLUFF 3,945 0.61 0.99 14.6 NE 2 NORTH CENTRAL 258760 VALENTINE MILLER AP CHERRY 2,590 0.73 1.22 18.3 NE 3 NORTHEAST 255995 NORFOLK AP MADISON 1,551 0.88 1.48 24.8 NE 5 CENTRAL 253395 GRAND ISLAND CTR NE AP HALL 1,840 0.88 1.45 23.9 NE 6 EAST CENTRAL 254795 LINCOLN AP LANCASTER 1,190 0.94 1.55 17.8 NE 7 SOUTHWEST 256065 NORTH PLATTE RGNL AP LINCOLN 2,778 0.81 1.25 19.4 NE 8 SOUTH CENTRAL 252560 EDISON FURNAS 2,120 0.90 1.41 21.2 NE 9 SOUTHEAST 258395 SYRACUSE OTOE 1,100 1.00 1.70 30.0 NH 1 NORTHERN 275639 MT WASHINGTON COOS 6,267 1.02 1.77 92.2 NH 2 SOUTHERN 271683 CONCORD ASOS MERRIMACK 346 0.85 1.33 38.1 NJ 1 NORTHERN 286026 NEWARK INTL AP ESSEX 7 0.99 1.61 44.0 NJ 2 SOUTHERN 280311 ATLANTIC CITY INTL AP ATLANTIC 60 1.01 1.63 41.2 NJ 3 COASTAL 281351 CAPE MAY 2 NW CAPE MAY 20 1.00 1.66 37.3 NM 1 NORTHWESTERN PLATEAU 293142 FARMINGTON AG SCI CTR SAN JUAN 5,625 0.50 0.70 7.7 NM 2 NORTHERN MOUNTAINS 292837 EL VADO DAM RIO ARRIBA 6,740 0.50 0.80 14.3 A-35 Read the entire page →
From page 68... ... NCHRP 25-41 Guidance for Achieving Volume Reduction of Highway Runoff in Urban Areas State Climate Division Number Climate Division Name Selected COOP Station COOP Station Name County Elevation, MSL Calculated 85th Percentile, 24-hour Storm Depth Calculated 95th Percentile, 24-hour Storm Depth Calculated Average Annual Precipitation Depth, inches NM 3 NORTHEASTERN PLAINS 292030 CONCHAS DAM SAN MIGUEL 4,244 0.80 1.30 13.7 NM 4 SOUTHWESTERN MOUNTAINS 292250 CUBERO CIBOLA 6,195 0.60 0.90 10.9 NM 5 CENTRAL VALLEY 290234 ALBUQUERQUE INTL AP BERNALILLO 5,310 0.51 0.77 8.6 NM 6 CENTRAL HIGHLANDS 297094 PROGRESSO TORRANCE 6,297 0.62 1.02 12.8 NM 7 SOUTHEASTERN PLAINS 290600 ARTESIA 6S EDDY 3,366 0.78 1.30 10.7 NM 8 SOUTHERN DESERT 294426 JORNADA EXP RANGE DONA ANA 4,266 0.65 1.07 9.2 NV 1 NORTHWESTERN 269171 WINNEMUCCA AP HUMBOLDT 4,296 0.39 0.58 7.9 NV 2 NORTHEASTERN 262631 ELY AIRPORT WHITE PINE 6,262 0.44 0.63 9.1 NV 3 SOUTH CENTRAL 268170 TONOPAH AIRPORT NYE 5,395 0.42 0.63 2.3 NV 4 EXTREME SOUTHERN 264436 LAS VEGAS AP CLARK 2,131 0.58 0.88 4.2 NY 1 WESTERN PLATEAU 303983 HORNELL ALMOND DAM STEUBEN 1,325 0.70 1.20 32.2 NY 2 EASTERN PLATEAU 300687 BINGHAMTON GREATER AP BROOME 1,595 0.74 1.16 37.1 NY 3 NORTHERN PLATEAU 303851 HIGHMARKET LEWIS 1,763 0.90 1.50 52.5 NY 4 COASTAL 305811 NEW YORK LA GUARDIA AP QUEENS 11 1.00 1.68 43.1 NY 5 HUDSON VALLEY 300042 ALBANY INTL AP ALBANY 275 0.80 1.27 36.7 NY 6 MOHAWK VALLEY 308586 TRIBES HILL MONTGOMERY 300 0.80 1.30 36.4 NY 7 CHAMPLAIN VALLEY 309389 WHITEHALL WASHINGTON 119 0.87 1.35 36.1 NY 8 ST. Read the entire page →
From page 69... ... NCHRP 25-41 Guidance for Achieving Volume Reduction of Highway Runoff in Urban Areas State Climate Division Number Climate Division Name Selected COOP Station COOP Station Name County Elevation, MSL Calculated 85th Percentile, 24-hour Storm Depth Calculated 95th Percentile, 24-hour Storm Depth Calculated Average Annual Precipitation Depth, inches OH 7 NORTHEAST HILLS 334992 MASSILLON STARK 930 0.90 1.40 11.2 OH 8 SOUTHWEST 332075 DAYTON WSO AP MONTGOMERY 1,000 0.80 1.34 37.5 OH 9 SOUTH CENTRAL 334004 JACKSON 3 NW JACKSON 800 0.90 1.45 36.7 OH 10 SOUTHEAST 338378 JENKINS DAM BURR OAK ATHENS 760 0.80 1.30 35.1 OK 1 PANHANDLE 343002 EVA TEXAS 3,574 0.80 1.30 15.1 OK 2 NORTH CENTRAL 343304 FORT SUPPLY 3SE WOODWARD 2,030 1.00 1.71 21.4 OK 3 NORTHEAST 348992 TULSA INTL AP TULSA 650 1.23 1.95 39.1 OK 4 WEST CENTRAL 345648 MAYFIELD BECKHAM 2,005 1.10 1.90 23.9 OK 5 CENTRAL 346661 OKLAHOMA CITY WILL ROGERS AP OKLAHOMA 1,285 1.17 1.87 33.2 OK 6 EAST CENTRAL 348497 STIGLER 1 SE HASKELL 570 1.35 2.30 43.1 OK 7 SOUTHWEST 343281 FT COBB CADDO 1,285 1.20 2.01 28.8 OK 8 SOUTH CENTRAL 344865 KINGSTON 5 SSE MARSHALL 684 1.34 2.18 38.0 OK 9 SOUTHEAST 340670 BENGAL 4 NNW LATIMER 667 1.40 2.40 48.3 OR 1 COASTAL AREA 350328 ASTORIA AP PORT OF CLATSOP 9 0.88 1.42 67.8 OR 2 WILLAMETTE VALLEY 356751 PORTLAND INTL AP MULTNOMAH 19 0.63 0.98 36.7 OR 3 SOUTHWESTERN VALLEYS 355429 MEDFORD INTL AP JACKSON 1,297 0.60 0.97 19.1 OR 4 NORTHERN CASCADES 352697 ESTACADA 24 SE CLACKAMAS 2,200 0.88 1.40 54.0 OR 5 HIGH PLATEAU 353232 GERBER DAM KLAMATH 4,850 0.60 1.20 17.7 OR 6 NORTH CENTRAL 356546 PENDLETON E OR RGNL AP UMATILLA 1,486 0.41 0.62 12.1 OR 7 SOUTH CENTRAL 354670 LAKEVIEW 2 NNW LAKE 4,890 0.50 0.79 15.4 OR 8 NORTHEAST 356845 PRAIRIE CITY RS GRANT 3,540 0.47 0.70 14.6 OR 9 SOUTHEAST 354321 JORDAN VALLEY MALHEUR 4,390 0.45 0.71 12.5 PA 1 POCONO MOUNTAINS 369705 WILKES-BARRE INTL AP LUZERNE 930 0.78 1.29 37.0 PA 2 EAST CENTRAL MOUNTAINS 360106 ALLENTOWN AP LEHIGH 390 0.99 1.57 44.1 PA 3 SOUTHEASTERN PIEDMONT 366889 PHILADELPHIA INTL AP PHILADELPHIA 10 0.99 1.60 41.5 PA 4 LOWER SUSQUEHANNA 363699 HARRISBURG CAPITAL CY YORK 340 0.84 1.47 32.5 A-37 Read the entire page →
From page 70... ... NCHRP 25-41 Guidance for Achieving Volume Reduction of Highway Runoff in Urban Areas State Climate Division Number Climate Division Name Selected COOP Station COOP Station Name County Elevation, MSL Calculated 85th Percentile, 24-hour Storm Depth Calculated 95th Percentile, 24-hour Storm Depth Calculated Average Annual Precipitation Depth, inches PA 5 MIDDLE SUSQUEHANNA 367931 SELINSGROVE 2 S SNYDER 420 1.00 1.70 24.6 PA 6 UPPER SUSQUEHANNA 368905 TOWANDA 1 S BRADFORD 760 0.80 1.21 32.7 PA 7 CENTRAL MOUNTAINS 362265 DU BOIS 7 E CLEARFIELD 1,670 0.75 1.15 40.6 PA 8 SOUTH CENTRAL MOUNTAINS 364001 HOLLIDAYSBURG 2 NW BLAIR 990 0.81 1.30 36.4 PA 9 SOUTHWEST PLATEAU 366993 PITTSBURGH ASOS ALLEGHENY 1,203 0.71 1.13 34.5 PA 10 NORTHWEST PLATEAU 362682 ERIE WSO AP ERIE 730 0.73 1.21 36.6 RI 1 ALL 376698 PROVIDENCE KENT 60 1.05 1.75 45.6 SC 1 MOUNTAIN 384581 JOCASSEE 8 WNW OCONEE 2,500 1.60 2.80 82.4 SC 2 NORTHWEST 383747 GRNVL SPART INTL AP SPARTANBURG 943 1.12 1.86 48.8 SC 3 NORTH CENTRAL 389327 WINNSBORO FAIRFIELD 560 1.20 1.90 35.6 SC 4 NORTHEAST 385306 LORIS 2 S HORRY 90 1.20 1.90 46.8 SC 5 WEST CENTRAL 386209 NEWBERRY NEWBERRY 476 1.20 1.90 44.9 SC 6 CENTRAL 381939 COLUMBIA METRO AP LEXINGTON 225 1.19 1.92 45.1 SC 7 SOUTHERN 381544 CHARLESTON INTL AP CHARLESTON 40 1.20 2.00 49.4 SD 1 NORTHWEST 394864 LEMMON PERKINS 2,567 0.71 1.20 16.7 SD 2 NORTH CENTRAL 396282 ONAKA 2N FAULK 1,610 0.80 1.40 18.1 SD 3 NORTHEAST 390020 ABERDEEN RGNL AP BROWN 1,297 0.79 1.32 18.6 SD 4 BLACK HILLS 396427 PACTOLA DAM PENNINGTON 4,720 0.70 1.20 18.5 SD 5 SOUTHWEST 392557 EDGEMONT FALL RIVER 3,610 0.62 1.02 15.0 SD 6 CENTRAL 396170 OAHE DAM STANLEY 1,660 0.80 1.30 15.0 SD 7 EAST CENTRAL 394127 HURON AP BEADLE 1,280 0.78 1.28 20.0 SD 8 SOUTH CENTRAL 395620 MISSION TODD 2,587 0.90 1.41 20.8 SD 9 SOUTHEAST 397667 SIOUX FALLS AP MINNEHAHA 1,428 0.85 1.41 23.9 TN 1 EASTERN 401656 CHATTANOOGA AP HAMILTON 671 1.12 1.79 53.1 TN 2 CUMBERLAND PLATEAU 406170 MONTEREY PUTNAM 1,860 1.19 1.82 55.7 TN 3 MIDDLE 406402 NASHVILLE ASOS DAVIDSON 600 1.05 1.75 47.8 A-38 Read the entire page →
From page 71... ... NCHRP 25-41 Guidance for Achieving Volume Reduction of Highway Runoff in Urban Areas State Climate Division Number Climate Division Name Selected COOP Station COOP Station Name County Elevation, MSL Calculated 85th Percentile, 24-hour Storm Depth Calculated 95th Percentile, 24-hour Storm Depth Calculated Average Annual Precipitation Depth, inches TN 4 WESTERN 405954 MEMPHIS INTL AP SHELBY 254 1.30 2.02 51.6 TX 1 HIGH PLAINS 415411 LUBBOCK INTL AP LUBBOCK 3,254 0.91 1.55 15.8 TX 2 LOW ROLLING PLAINS 419729 WICHITA FALLS MUNI AP WICHITA 1,017 1.13 1.86 27.5 TX 3 NORTH CENTRAL 413284 FT WORTH MEACHAM FLD TARRANT 687 1.20 2.03 28.6 TX 4 EAST TEXAS 419665 WHEELOCK ROBERTSON 420 1.36 2.20 36.6 TX 5 TRANS PECOS 412797 EL PASO AP EL PASO 3,918 0.60 1.04 8.5 TX 6 EDWARDS PLATEAU 418845 TARPLEY BANDERA 1,390 1.30 2.22 31.3 TX 7 SOUTH CENTRAL 410428 AUSTIN CAMP MABRY TRAVIS 670 1.21 2.01 32.3 TX 8 UPPER COAST 419364 VICTORIA ASOS VICTORIA 115 1.32 2.30 30.5 TX 9 SOUTHERN 414191 HINDES ATASCOSA 360 1.30 2.38 23.5 TX 10 LOWER VALLEY 411136 BROWNSVILLE INTL AP CAMERON 24 1.17 2.28 25.7 UT 1 WESTERN 422090 DELTA MILLARD 4,620 0.45 0.69 7.7 UT 2 DIXIE 427516 ST GEORGE WASHINGTON 2,770 0.55 0.80 7.1 UT 3 NORTH CENTRAL 427598 SALT LAKE CITY INTL AP SALT LAKE 4,225 0.51 0.80 15.3 UT 4 SOUTH CENTRAL 426135 NEPHI JUAB 5,128 0.50 0.75 14.3 UT 5 NORTHERN MOUNTAINS 422385 ECHO DAM SUMMIT 5,470 0.50 0.70 14.0 UT 6 UINTA BASIN 427395 ROOSEVELT RADIO UINTAH 5,014 0.46 0.70 6.8 UT 7 SOUTHEAST 420738 BLANDING SAN JUAN 6,032 0.58 0.90 11.6 VA 1 TIDEWATER 446139 NORFOLK INTL AP NORFOLK (CITY) Read the entire page →
From page 72... ... NCHRP 25-41 Guidance for Achieving Volume Reduction of Highway Runoff in Urban Areas State Climate Division Number Climate Division Name Selected COOP Station COOP Station Name County Elevation, MSL Calculated 85th Percentile, 24-hour Storm Depth Calculated 95th Percentile, 24-hour Storm Depth Calculated Average Annual Precipitation Depth, inches VT 3 SOUTHEASTERN 438556 UNION VILLAGE DAM ORANGE 460 0.77 1.26 34.3 WA 1 WEST OLYMPIC COAST 456858 QUILLAYUTE AP CLALLAM 185 1.20 1.97 101.9 WA 2 NE OLYMPIC SAN JUAN 456678 PORT TOWNSEND JEFFERSON 100 0.46 0.72 22.3 WA 3 PUGET SOUND LOWLANDS 456114 OLYMPIA AP THURSTON 188 0.79 1.27 47.9 WA 4 E OLYMPIC CASCADE FOOTHILLS 453357 GREENWATER PIERCE 1,730 0.79 1.31 52.6 WA 5 CASCADE MOUNTAINS WEST 458009 STAMPEDE PASS KITTITAS 3,959 1.07 1.80 80.3 WA 6 EAST SLOPE CASCADES 454849 LUCERNE 1 N CHELAN 1,200 0.68 1.16 26.7 WA 7 OKANOGAN BIG BEND 453515 HARRINGTON 1 NW LINCOLN 2,160 0.50 0.66 12.7 WA 8 CENTRAL BASIN 458207 SUNNYSIDE YAKIMA 747 0.40 0.60 7.6 WA 9 NORTHEASTERN 457938 SPOKANE INTL AP SPOKANE 2,353 0.45 0.66 16.5 WA 10 PALOUSE BLUE MOUNTAINS 456789 PULLMAN 2 NW WHITMAN 2,545 0.51 0.80 21.4 WI 1 NORTHWEST 470349 ASHLAND EXP FARM BAYFIELD 650 0.80 1.34 28.9 WI 2 NORTH CENTRAL 476939 RAINBOW RSVR TOMAHAWK ONEIDA 1,600 0.74 1.20 27.9 WI 3 NORTHEAST 476510 PESHTIGO MARINETTE 600 0.80 1.30 28.7 WI 4 WEST CENTRAL 475948 NEW RICHMOND ST. Read the entire page →
From page 73... ... NCHRP 25-41 Guidance for Achieving Volume Reduction of Highway Runoff in Urban Areas State Climate Division Number Climate Division Name Selected COOP Station COOP Station Name County Elevation, MSL Calculated 85th Percentile, 24-hour Storm Depth Calculated 95th Percentile, 24-hour Storm Depth Calculated Average Annual Precipitation Depth, inches WY 1 YELLOWSTONE DRAINAGE 485345 LAKE YELLOWSTONE TETON 7,870 0.43 0.70 20.2 WY 2 SNAKE DRAINAGE 486440 MORAN 5 WNW TETON 6,798 0.50 0.77 23.5 WY 3 GREEN AND BEAR DRAINAGE 487845 ROCK SPRINGS AP SWEETWATER 6,741 0.40 0.60 4.2 WY 4 BIG HORN 488852 TENSLEEP 4NE WASHAKIE 4,815 0.60 0.90 12.9 WY 5 POWDER, LITTLE MISSOURI, TONGU 488155 SHERIDAN AP SHERIDAN 3,945 0.52 0.83 14.3 WY 6 BELLE FOURCHE DRAINAGE 487270 PINE TREE 9 NE CAMPBELL 5,111 0.60 1.11 11.5 WY 7 CHEYENNE & NIOBRARA DRAINAGE 486660 NEWCASTLE WESTON 4,315 0.60 1.00 15.0 WY 8 LOWER PLATTE 481570 CASPER WSCMO NATRONA 5,338 0.45 0.80 11.9 WY 9 WIND RIVER 485390 LANDER AP FREMONT 5,557 0.60 0.97 12.9 WY 10 UPPER PLATTE 487105 PATHFINDER DAM NATRONA 5,918 0.50 0.75 9.2 A-41 Read the entire page →

From page 31...

... Annex A Volume Performance Tool Technical Documentation 1 Introduction and Purpose ..................................................................................................................... 1 2 Model Overview .....................................................................................................................................