Paxton Creek Watershed TMDL Strategy

Transcription

1 Paxton Creek Watershed TMDL Strategy Public Review Meetings: November 17, 2015 November 18, 2015 December 10, 2015 Paxton Creek Watershed Cooperative Progressive approach to achieving water quality improvements. Long-term partnership to define, implement integrated solutions. Seek affordable schedule considering regional financial capabilities. Collaboration to seek outside financial support. 2

2 Paxton Creek Watershed Facts Paxton Creek drains over 27 square miles of metropolitan Harrisburg. Pennsylvania DEP considers 20 miles of Paxton Creek impaired by sediment and habitat degradation. Over 85 percent of the sediment is contributed by stream erosion. 3 Paxton Creek Watershed Facts In 2008, USEPA defined a Total Maximum Daily Load (TMDL) for Paxton Creek the allowable sediment load to resolve impairment. (Note: Phosphorus was removed from the TMDL at a later date) Source Land Use / Source Existing Load (ton/year) Allocated Load (ton/year) Percent Reduction Nonpoint Sources Agriculture % Forest % Open Space % Low Intensity Development % High Intensity Development % Instream Erosion % Nonpoint Source Subtotal % Municipal Separate Storm Sewer Systems (MS4) Agriculture % Forest % Open Space % Low Intensity Development % High Intensity Development % Instream Erosion % MS4 Subtotal 2, , % CSO % Permitted Facilities % Total 2, , % 4

3 Paxton Creek Watershed Facts The City of Harrisburg, Lower Paxton Township, and Susquehanna Township comprise over 98 percent of the Paxton Creek Watershed. Capital Region Water (CRW) owns and operates combined and separate storm sewer systems within the City of Harrisburg. A myriad of entities discharge to Paxton Creek. Table 2-1. Approximate Drainage Areas within Paxton Creek Watershed Approximate Drainage Area (acres) Jurisdiction Separate (to MS4 Outfall) Combined (to CSO) Other MS4s 1 Direct Drainage 2 Non-Urban Area 3 Total Capital Region Water / Harrisburg 148 1, ,348 Lower Paxton Township 4, ,885 7,395 Susquehanna Township 4, , ,413 Middle Paxton Township Penbrook Borough Swatara Township Total 9,562 1,720 1,839 1,464 2,836 17,421 1 For example, PennDOT, Commonwealth of Pennsylvania, Harrisburg Area Community College, Dauphin County 2 Private property not discharging to an MS4, where known; included in Separate (to MS4 Outfall) area where unknown. 3 Non-urban areas are areas not defined as an urbanized area by the 2000 U.S. Census 5 Responding to the TMDL DEP requires MS4s to prepare and implement a 2-phase TMDL Plan, consisting of: A TMDL Strategy (due December 31, 2015) that outlines the type/extent of projects, operational practices, and/or policies they plan to implement to meet the TMDL. A TMDL Design Details Plan (Due September 2017) that provides site-specific information about and an implementation schedule for the proposed controls. CRW, Lower Paxton Township, and Susquehanna Township proposed, and DEP agreed, that a single TMDL Strategy for the entire watershed (Watershed TMDL Strategy) would satisfy permit requirements. 6

4 Responding to the TMDL A MapShed model of Paxton Creek matching the 2008 TMDL existing loading was created. The model estimates that seven projects constructed since 2008 have reduced the sediment load by 57.9 ton/year. With these projects, an additional ton/year sediment load reduction is required to achieve the TMDL. 7 Responding to the TMDL The MapShed model projects that the following controls will achieve the remaining ton/year sediment load reduction: Anticipated controls for CRW s combined sewer overflows (CSOs). 11 miles of stream stabilization (includes.. 9 miles of riparian area enhancement). New/retrofit land-based BMPs serving 10 percent of the watershed. Preservation of existing riparian areas. Continued enforcement of construction site erosion and sediment control. Appropriate maintenance of stormwater controls. 8

5 Responding to the TMDL An initial assessment of 8.2 miles of Paxton Creek (18 reaches) utilized the Unified Stream Assessment (USA) method: Eight reaches received optimal/ suboptimal scores may be considered reference reaches. Eleven reaches received marginal/ poor scores, exhibiting erosion, physical constraints, and poor riparian function. 9 Responding to the TMDL 10

6 Responding to the TMDL 18 potential early action projects were identified at locations of extreme stream erosion. 3 projects were recommended for implementation during development of TMDL Design Details where erosion threatened public infrastructure and/or property. Early action projects will also be pursued in CRW s combined sewer system. 11 Responding to the TMDL: Stream Stabilization Options Bioengineered Bank Stabilization Outlet Protection/ Velocity Dissipation Naturalized Drainage Channel Floodplain Connection Grade Control 12

7 Next Steps: TMDL Design Details Plan Complete field assessment of stream channel stability. Develop and apply a hydrologic/hydraulic model. Prepare/prioritize design concepts: Stream-based (restoration, preservation). Land-based (capture sediment, enhance flows). Multi-objective benefits (e.g., community development, flood control, recreation). Define implementation requirements: Additional collaborative partners / cost-share / funding Compliance monitoring / modeling (adaptive management) Integrated, affordable stormwater/wastewater compliance schedule Complete plan by September We want your feedback Review the strategy, submit your comments at: ; Capital Region Water, 212 Locust Street, Suite 500, Harrisburg, PA Lower Paxton Township, 425 Prince Street, Harrisburg, PA Susquehanna Township, 1900 Linglestown Road, Harrisburg, PA. Ask questions / provide comments tonight. Future Board considerations: Budget Long-term support Water quality awareness 14

8 Questions?