Anacostia River Watershed Restoration Plan Fort Dupont Subwatershed Provisional Restoration Project Inventory - July 2009 Table of Contents I. Background ................................................................................................................. 2 II. Restoration Inventory .................................................................................................. 3 A. Impervious Features Summary ............................................................................ 4 B. Existing Stormwater Management Facilities Summary ...................................... 7 C. Candidate Restoration Project Summary ........................................................... 10 D. Fort Dupont Candidate Restoration Projects ..................................................... 13 1 I. Background The Fort Dupont tributary is a third order tributary to the Anacostia River and is 443 acres (0.69 square miles). Although the tributary lies entirely within the District of Columbia, the National Park Service (NPS) owns about 85-percent of the land (376 acres) drained by Fort Dupont and its three small tributaries. Approximately 80-percent of the NPS-owned land is forested by mature eastern hardwoods. The average impervious level in the watershed is 13.3-percent, located primarily in the watershed’s headwaters. Despite this relatively low level of imperviousness, the impacts of uncontrolled stormwater runoff to the stream channel are clear. Approximately 1.5 miles of the Fort Dupont’s 1.9-mile main stem has unstable, eroding banks, caused by downcutting. These unstable banks contribute sediment to the Anacostia River. Since approximately 85-percent of the watershed is part of Fort Dupont National Park, which is used as recreational/preserved lands and is covered by eastern deciduous hardwoods, nutrient loading of the tributary is less of a concern. The upper portion of the watershed does, however, lie in residential areas, which contribute runoff pollution to the stream in the form of oil and other automobile fluids. Measurements taken during storm events also show that high stormwater flows may also move high levels of copper (Cu) and iron (Fe) from the stream banks into the stream. Approximately 2,240 linear feet of the Fort Dupont tributary is piped, prohibiting all fish migration and decreasing the habitat area for macro-invertebrates. The longest piped sections are at the downstream end of the tributary and the section that passes under Fort Davis drive and the associated fill area. Recognizing both the severity and extent of environmental and ecological problems affecting the Anacostia River watershed and the need to better coordinate restoration efforts and resources, the three jurisdictions and the Metropolitan Washington Council of Governments entered into a Federal cost-sharing agreement with the U.S. Army Corps of Engineers to prepare a 10-year watershed restoration plan. The Anacostia River Watershed Restoration Plan will identify opportunities and approaches for restoring and protecting the 14 major subwatersheds and the tidal river reach within the Anacostia River basin. 2 Northwest Paint )"108 Branch Branch Little Paint Branch )"97 "198 Prince )"28 ) )"650 George's )"198 County )"182 Indian ut29 Creek Upper Beaverdam Lower Creek ¦¨§95 Ely d n Montgomery 2 Montgomery d 197 3 E )" r 3 3 a t o s F County 895 e )" n 295 in ÆÄ M 295 t )" t n 97 s a )" 1 G R s 3 s i d d i n F g o o r r e 201 2 t Du 3 ¦¨§495 )" C pont F Trib o utar rt y D e 516 l u )" d p n o a n C t h A R B M a la a u p ss r b 320 a n l a )" 193 c in )" hu s m L s ou et F a d ts o r t R 787 )" D id M g h a e t v h t 4 is 4 3 195 3 )" Still Creek )"212 Middle n we District of Brier Ditch Bo District of )"410 Ma B ss e ac c hu ma k 501 se Alaba Columbia )" tts )"450 Upper )"208 Hickey Run )"202 Lower ut29 Beaverdam )"295 ut50 Creek )"704 ut50 ¦¨§395 )"214 )"332 ± Watts Branch Fort Dupont ¦¨§295 ± 0123 Miles Pope Branch Tributary Fort Dupont Tributary Figure 1- Fort Dupont Subwatershed Figure 2- Fort Dupont Subwatershed Unit II. Restoration Inventory The following sections include stormwater retrofit, stream restoration, wetland restoration, fish blockage removal, and riparian restoration projects, and actions for further evaluation by others. As previously noted, the restoration projects presented herein are conceptual or planning level only. It is recognized that more detailed drainage and site analyses are required, and that facility size and costs shown represent approximations. To facilitate reader understanding of the Fort Dupont Subwatershed: Provisional Restoration Project Inventory, information has been organized into the following four sections: Section A - Impervious Features Summary Section B - Existing Stormwater Management Facilities Summary Section C - Candidate Restoration Project Summary Section D - Fort Dupont Candidate Restoration Projects 3 A. Impervious Features Summary 4 Figure 3 - Summary: Fort Dupont Impervious Features Lower Ely d n d 2 E r 3 3 3 a t o s F e n 295 in ÆÄ M t t n s a 1 s 3 G s R i i o d r F g d C o rt e n Dup 2 ont 3 F Tri o buta rt ry D e l u d p n o a n C t h A R B a la u p r b n l M in a L as s m o sa For ud ch a us e t t R ts D i M dg a h e t v h 4 i s 4t 3 3 Middle wen Bo Ma B ss e ac c hu ma k se laba tts A Upper Legend Streams Subcatchment Subwatershed Unit Waterbody Buildings ± Roads, Parking Lot, and Sidewalks 0 750 1,500 3,000 Feet 5 Table 1. Fort Dupont: Summary - Impervious Surfaces Category Acres Miles 1. Roads 26.1 8.5 a. State/Fed 1.9 0.1 b. Local 24.2 8.4 2. Parking Lots 10.6 a. Public/Institutional 9.9 b. Private 0.7 3.Roofs 12.6 a. Public/Institutional 2.3 b .Private 0.1 c. Single Family 10.2 3. Other a. Sidewalks * 3.0 b. Single Family Driveways ^ 5.3 Total 57.6 Avg. % Imperviousness 12% # of Single Family Homes 379 Total Drainage area 494 ^ Driveways assumptions Average Driveway=0.014 Acres Width equal to 4 feet with a sidewalk running the * Sidewalks assumptions length of one side of the road. Note: Drainage area and tributary area calculated using the USGS 30-meter digital elevation model (DEM) 6 B. Existing Stormwater Management Facilities Summary 7 Figure 4 - Summary: Fort Dupont Existing Stormwater Management BMP Sites ! Lower Area: 106 ac # of BMPs: 0 Ely d n ! d 2 E r ! 3 3 ! 3 a t o s F e n 295 in ÆÄ M t t n 1s a G 3 !! R s s i i d g o F d o r rt e n D C up 2 ont 3 F Tri o buta rt ry D e u l p d o n n C ! t A a B h ! a la R u p r b n l M in a L as s m o sa For ud ch a us e t t R ts D i M dg a e th v h 4 i s 3 4t 3 Middle Area: 224 ac wen # of BMPs: 2 Bo Ma B ss e ac c hu ma k se laba tts A Upper Area: 201 ac # of BMPs: 0 Legend Subwatershed Unit ! Existing Stormwater BMP Stormwater Controlled Drainage Area ± Subcatchment 0 750 1,500 3,000 Feet 8 Table 2. Fort Dupont: Summary –Existing Stormwater Management BMPs No. of Percent of D.A. Controlled Type Facilities Total BMP's (ac.) 1. Dry Pond 2. ED Dry Pond 3. Wet Pond 4. ED Wet Pond 5. Wetland (non-ED and ED) 6. Infiltration (Trench or Basin) 7. Oil Grit Separator Water Quality Inlet (e.g. 8. Stormreceptor, Bay Saver, etc) Bioretention /Rain Garden 9. 5 100.0 2.4 10. 'Green Street'* 11. Bioswale 12. Grass Swale w/ Check Dams 13. Porous Pavement 14. Sand Filter 15. Underground Pipe Storage 16. Cistern 17. Green Roof 18. Other Total 5 100.0 2.4 May include a mix of LID techniques including, but not limited to: bioretention, * rain garden, bioswale, soil amendment, etc. 9 C. Candidate Restoration Project Summary 10 Table 3. Summary: Restoration Candidate Projects Impervious Number Estimated Acreage Length Acreage Candidate Project Type of Cost ($) Controlled (ft) (ac) Projects (ac) 1 Stormwater Retrofit 16 4,575,133 42.8 - 72.5 2 Stream Restoration 7 2,280,000 - 7,600 - 3 Wetland Creation/Restoration 2 30,000 - - 0.6 Fish Blockage 4 11 5,175,000 - 8,185 - Removal/Modification Riparian Reforestation, 5 Meadow Creation, Street Tree 1 14,000 - - 1.0 and Invasive Management 6 Trash Reduction 0 - - - - 7 Toxic Remediation 0 - - - - 8 Parkland Acquisition 2 2,370,000 - - 23.7 Total 39 14,444,000 42.8 15,785 97.8 11 Table 4. Fort Dupont Subwatershed: Provisional Restoration Project Inventory ‘Unit Costs’* No. Practice Approx. Unit Cost ($) Stormwater Retrofit Existing Stormwater Management 1 ~ $1,000-3,000/acre of drainage Pond/Wetland Retrofitting New Stormwater Management 2 ~$3,000-5,000/acre of drainage Pond/Wetland Construction LID-Bioretention (w/Underdrain 3 ~ $100,000/ impervious acre System) 4 LID-Curbside/Street Planter ~ $100,000/ impervious acre 5 LID-Tree Box Filter ~ $54,450 - $65,340/impervious acre 6 LID-Green Roof ~ $42/square foot LID-Single Family Home Rain 7 ~ $5,000 per individual garden Garden LID-Single Family Home Rain 8 ~ $200/barrel (Typically, two per house) Barrel 9 Sand Filter ~ $20,000 to $25,000 per impervious acre** 10 Underground Pipe Storage ~ $15,000 per impervious acre*** 11 Permeable Pavement ~ $4.00 per square foot 12 LID Bioswale ~ $100,000/impervious acre 13 Storm Filter ~ $80,000/acre Stream Restoration/Fish Passage/Wetland Creation 14 Stream Restoration ~ $300/LF 15 Concrete Stream Channel Removal ~ $1,000/LF 16 Stream ‘Day Lighting’ ~ $2,000/LF Regenerative Stormwater 17 ~ $370/ft Conveyance System Fish Passage/Riffle Grade Control 18 ~ $150,000 per one foot barrier height Structure 19 Wetland Creation ~50,000/Acre Riparian Reforestation/Meadow Creation/ Invasive Plant Management 20 Riparian Reforestation ~ $9,000/acre 21 Wildflower Meadow Creation ~ $5,000/acre 22 Invasive Plant Management ~ $5,000/acre Trash Reduction/Water Quality 23 Manual Trash Pickup ~ $300/100 LF 24 Fresh Creek Trash Netting System ~ $1,000/acre of drainage 25 Signage ~ $1600 26 End–of-Pipe Trash Catching System ~ $4,000/ acre of drainage 27 Street Sweeping**** ~ $50/curb mile/year 28 Storm Drain Trash Grate ~ $500/inlet Land Acquisition 29 Land Acquisition ~ $100,000/acre *includes (where appropriate) design and construction/installation costs ** escalated to 2009 dollars from “Schueler, T.R.