Incorporating Restoration Planning and Transportation Controls into the Valley Creek Watershed Act 167 Stormwater Management Plan

Transcription

1 Incorporating Restoration Planning and Transportation Controls into the Valley Creek Watershed Act 167 Stormwater Management Plan Pennsylvania State Section American Water Resources Association Fall 2011 Conference

2 DISCUSSION TOPICS Unique Elements of the Valley Creek Stormwater Management Plan 1. Background of Plan 2. Transportation Standards 3. Improvement Plan

3 DISCUSSION TOPICS Unique Elements of the Valley Creek Stormwater Management Plan 1. Background of Plan 2. Transportation Standards 3. Improvement Plan

4 DISCUSSION TOPICS Unique Elements of the Valley Creek Stormwater Management Plan 1. Background of Plan 2. Transportation Standards 3. Improvement Plan

5 BACKGROUND OF THE PLAN

6 PROJECT TEAM Chester County Water Resources Authority Planning Commission Conservation District Montgomery County Planning Commission Conservation District CONSULTING ENGINEER

7 PROJECT PARTNERS PADEP Harrisburg Southeast Region Municipalities PennDOT PA Turnpike Commission Valley Creek Restoration Partnership Valley Forge National Historical Park

8 Location of Valley Creek Watershed Harrisburg Area Community College

9 Watershed Plan Advisory Committee

10 Drivers of the Plan

11 Driver Valley Forge National Historical Park

12 Driver Valley Forge National Historical Park

13 Driver Valley Forge National Historical Park

14 Flow (cfs) ) Goal: 10% Reduction in Current Volume and Rate Valley Creek at PA Turnpike Bridge near Valley Forge, PA Hypothetical Fully Forested Pre-Existing (1937) Existing (2005) Future Time (Hours)

15 Standards for State Roadway Projects

16 Breakdown of Plan Advisory Areas of Jurisdiction/Management Tredyffrin Township 46.7% East Whiteland Township 40.2% Valley Forge Nat l Hist. Park 5.7% Charleston Township 5.6% PennDOT 3.1% Willistown Township 2.6% Malvern Borough 2.1% Schuylkill Township 1.4% Penn Turnpike Commission 1.3% Upper Merion Township 1.3%

17 Breakdown of Plan Advisory Areas of Jurisdiction/Management Tredyffrin Township 46.7% East Whiteland Township 40.2% Valley Forge Nat l Hist. Park 5.7% Charleston Township 5.6% PennDOT 3.1% Willistown Township 2.6% Malvern Borough 2.1% Schuylkill Township 1.4% Penn Turnpike Commission 1.3% Upper Merion Township 1.3%

18 Standards for 13 Provisions Applicability Volume/Thermal Infiltration Rate Ground Cover Downgradient Properties O&M Alternative Approach

19 For Six Categories of Projects Road Maintenance, Bridge Replacement Projects, Minor Roadway Upgrade Projects, Major Roadway Upgrade Projects, New Roadway or Facility Projects, Pedestrian / Bicycle Facilities

20 For Six Categories of Projects Road Maintenance

21 Mandatory Minimum Standards For ROAD MAINTENANCE ACTIVITIES Applicability Thresholds Volume / Quality / Thermal Infiltration Ground Cover Assumptions Peak Rate Large storms Peak Rate Smaller storms Stream Channel Protection Any project that meets 25 Pa. Code 102 definition for road maintenance Not quantitative measure. Look for opportunities Not quantitative measure. Look for opportunities Not applicable because there are no quantitative measures. Not quantitative measure. Look for opportunities Not quantitative measure. Look for opportunities Not applicable.

22 Mandatory Minimum Standards For ROAD MAINTENANCE ACTIVITIES Selected Measures to be Used Impervious disconnection (e.g., disperse flow using a level spreader, discharge through a vegetated swale prior to reaching a surface water) Slope roughening (when a slope must be re-graded to maintain the road) Restore riparian vegetation (within the right-of-way) Convert an existing v-shaped vegetated channel into a vegetated swale BMP Preserve trees and re-vegetate using native plant species

23 For Six Categories of Projects Bridge Replacement

24 Mandatory Minimum Standards For BRIDGE REPLACEMENT PROJECTS Applicability Thresholds Volume / Quality / Thermal Infiltration Ground Cover Assumptions Peak Rate Large storms Peak Rate Smaller storms Stream Channel Protection All bridge replacements that are not required to obtain coverage under a NPDES permit. Not quantitative measure. Look for opportunities Not quantitative measure. Look for opportunities Not applicable because there are no quantitative measures. Not quantitative measure. Look for opportunities Not quantitative measure. Look for opportunities Not applicable.

25 Mandatory Minimum Standards For BRIDGE REPLACEMENT PROJECTS The goal for bridge projects to is maintain sheet flow as much as practicable through vegetated slopes in order to provide a proven, low cost, low maintenance, non-structural BMP. Impervious disconnection Slope roughening Protect and restore riparian vegetation (within the right-of-way) Convert an existing v-shaped vegetated channel into a vegetated swale BMP Preserve trees and re-vegetate using native plant species

26 For Six Categories of Projects Minor Roadway Projects

27 Mandatory Minimum Standards For MINOR ROADWAY UPGRADE PRJS The result of the activity is a minor increase in impervious area relative to existing conditions and does not generally change the direction of runoff or the potential for pollutants in the runoff. Significant acquisition of right-of-way is not typically within the project scope. Measures listed in previous categories Soil amendment (e.g., replace poorly draining soils in swales) Vegetated swale Bioretention (e.g., retrofit in medians or interchanges) Bioslope (where embankment will be disturbed)

28 Mandatory Minimum Standards For MINOR ROADWAY UPGRADE PRJS Applicability Thresholds Volume / Quality / Thermal Infiltration Ground Cover Assumptions Peak Rate Large storms Peak Rate Smaller storms Stream Channel Protection Increase in net impervious area. Less than 10 feet in cross-section. Permanently remove the net increase in runoff from the 2-year. Infiltrate the first one-half inch of runoff from the net new impervious area. 20% of the existing impervious area over has a ground cover of Meadow. No quantitative measure. No quantitative measure. Not applicable.

29 For Six Categories of Projects Major Roadway Projects

30 Mandatory Minimum Standards For MAJOR ROAD UPGRADE PRJS Major roadway upgrades are considered capacity adding projects and are characterized by significant increases in impervious area. Acquisition of right-of-way is sometimes necessary to accommodate the expansion. Measures listed in previous categories, Dry extended detention basin, Infiltration trench, Infiltration basin, Infiltration berm, Wet pond,

31 Mandatory Minimum Standards For MAJOR ROAD UPGRADE PRJS Applicability Thresholds Increase in net impervious area. Minimum 10 feet in cross-section. Volume / Quality / Thermal Infiltration Ground Cover Assumptions Post-development runoff volume shall not exceed the pre-development runoff volume for the 2-year storm Infiltrate the first one inch of runoff from the net new impervious area. 20% of the existing impervious area over has a ground cover of Meadow. Peak Rate Large storms Post-development = pre-development for 10- yr to 100-yr Peak Rate Smaller storms Post-development for 5-yr and 2-yr = Pre-development for 1-yr Stream Channel Protection Not applicable.

32 For Six Categories of Projects New Roadway or Facility Projects

33 Mandatory Minimum Standards For NEW ROADWAY OR FACILITY PRJS The activities in this category involve the construction of a new roadway or support facility. Post-construction runoff characteristics would be substantially different than pre-construction characteristics if no stormwater controls were implemented. Measures listed in previous categories, Permeable pavement (per PennDOT policy, not underneath the roadway pavement) Constructed wetland,

34 Mandatory Minimum Standards For NEW ROADWAY OR FACILITY PRJS Applicability Thresholds Volume / Quality / Thermal Infiltration Ground Cover Assumptions Increases the impervious ground cover over previously undeveloped ground. Post-development runoff volume shall not exceed the pre-development runoff volume for the 2-year storm Infiltrate a minimum of one inch of runoff from all areas disturbed. Utilize new development ground cover as specified for conventional development. Peak Rate Large storms Post-development = pre-development for 10- yr to 100-yr Peak Rate Smaller storms Post-development for 5-yr and 2-yr = Pre-development for 1-yr Stream Channel Protection Attenuate the 1-year, 24-hour storm for at least 24 hours.

35 For Six Categories of Projects Pedestrian/Bicycle Facilities.

36 Mandatory Minimum Standards For PEDESTRIAN / BICYLCE FACILITIES The standards applied to pedestrian and bicycle facilities will be determined by the overall type of project. If the pedestrian/bicycle facility is being constructed as part of a new roadway project, then the standards contained in this Plan for new roadways would apply. The minor roadway upgrade project standards would apply to a pedestrian/bicycle facility which is the only upgrade to the existing roadway and is adjacent to the existing roadway. The use of pervious surfaces such as dirt or wood chips exempts the facility from these standards.

37 Additional Provisions Protection of Downgradient Properties for Off-Site Conveyance Inlet and outlet ditches shall be maintained as far as necessary to achieve free flow of drainage to and from the outlet pipe, while avoiding excessive volume or velocity of water discharged onto private property. Outlet protection or a drop structure shall be provided for the following locations where outlet velocities exceed that capacity of downstream areas to resist erosion: storm drains, sediment traps, sediment basins, stormwater management basins, temporary slope pipes, ditches or channels (temporary or permanent).

38 Additional Provisions Long-Term Operation and Maintenance Responsibilities All stormwater management facilities and their appurtenant structures shall be maintained to provide for their effective long term operation and performance. This maintenance standard applies for all stormwater management facilities and their appurtenant features

39 Additional Provisions Alternative Approach Where it proves to be impracticable for the transportation agency to meet one or more of the mandatory minimum standards presented herein onsite, and only after a close evaluation of alternative site designs, the transportation agency shall work with the municipality and PA DEP to develop alternative measures.

40 Watershed Improvement Plan

41 Five Recommended Actions Watershed Coordination, Improving the Understanding of Runoff and Increasing Stewardship, Restoring the Hydrologic Regime, Restoring the Flood Carrying Capacity, & Improving Water Quality and Reducing Erosion and Sedimentation.

42 Watershed Coordination

43 Watershed Coordination Target: Annual watershed summit that is well-represented by various stakeholders Benchmarks: A1. Develop a Prioritized List of Projects for Implementation A2. Five Watershed Summits held (one each year)

44 Improving the Understanding of Runoff and Increasing Stewardship

45 Improving the Understanding of Runoff and Increasing Stewardship Targets: A. Outreach to each resident in the watershed at least 3 times each year. B. Stream Clean-up days held at 10 locations in the watershed Benchmarks: A.20,000 person contacts annually (repeated contacts encouraged) B. Stream Clean-up days held in 4 locations annually

46 Restoring the Hydrologic Regime

47 Restoring the Hydrologic Regime Targets: A. Reduce by 60% the difference in existing volume of runoff generated from a 1-inch storm compared to a meadow condition. B. Preserve an acre of land for every acre of new development. C. Achieve a 10% reduction in the peak rate of runoff for all storms throughout the watershed.

48 Restoring the Hydrologic Regime Benchmarks: A. One million gallons of stormwater collected and removed from runoff from 1-inch storms. B. 90 acres of lands preserved. C. Achieve a 1% reduction in the peak rate of runoff, which equates to a 64 cfs reduction in the peak rate for a 100-year storm at the USGS stream gage.

49 Restoring the Flood Carrying Capacity

50 Restoring the Flood Carrying Capacity Targets: A.80% of stream miles are connected to its floodplain B. 90% of culverts/bridges can safely pass the 5-yr storm, & 80% of culverts/bridges safely pass the 10-yr storm. C. 100% of stormwater management facilities will have a maintenance plan and an identified responsible party for long-term maintenance.

51 Restoring the Flood Carrying Capacity Benchmarks: A. 1,500 linear feet of stream restored B. 16 culverts improved C. 20% of existing stormwater systems will have an identified owner and a maintenance plan D. 100% of new stormwater systems will have an identified owner and a maintenance plan

52 Improving Water Quality and Reducing Erosion and Sedimentation

53 Improving Water Quality and Reducing Erosion and Sedimentation Targets: A. 100% of streams attaining all Pennsylvania designated uses B. 75% of stream reaches have wooded buffers on each side C. Native trees and vegetation to be more prevalent D. 50% of existing stormwater basins retrofitted to also improve water quality

54 Improving Water Quality and Reducing Erosion and Sedimentation Benchmarks: A. 1,500 linear feet of stream restored B. 2.5 acres of new or enhanced riparian buffers created C. 1,500 native trees and shrubs planted throughout the watershed (in addition to stream restoration plantings) D. 3 stormwater basins retrofitted to improve infiltration and/or

55 Craig Thomas Chester County Water Resources Authority

56 Pace of the Project 2004 to 2010

57 Phase I and Watershed Assessment

58 Characterizing the Watershed

59 Historic Mills and Dams

60 Obstructions

61 Goals and Objectives: Local and State Driven

62 Modeling of Multiple Land Use/ Land Cover

63 Modeling of Land Cover Conversion

64 Equitable Approach to Stormwater Management: Rate Control

65 Watershed Map

66 Original Approach: Release Rate Factors based on Subwatershed

67 Final Approach: Use Meadow Ground Cover *

68 * Promoting Re-Development: 20% Meadow

69 Municipal Implementation Technical Standards, not a Model Ordinance