The New Jersey Nonstructural Strategies Point System (NSPS)

Transcription

1 2011 Low Impact Development Symposium The New Jersey Nonstructural Strategies Point System (NSPS)

2 NJDEP SWM Rules (NJAC 7:8) Issued Jointly with NJDEP Municipal Stormwater Regulation Program (NJAC 7:14) in 2004 Developed in Response to 1999 EPA Final Phase II Stormwater Rules SWM Rules Address Phase II Rules Post-Construction Stormwater Management Requirements

3 NJDEP SWM Rules (NJAC 7:8) Four Primary Design Requirements: Stormwater Quality Standards Stormwater Quantity Standards Groundwater Recharge Standards Nonstructural Stormwater Strategies

4 Nonstructural Stormwater Management Strategies From NJAC 7:8-5.2 (a): Stormwater management measures for major developments shall be developed to meet the erosion control, groundwater recharge, stormwater runoff quantity, and stormwater runoff quality standards at NJAC 7:8 5.4 and 5.5.

5 Nonstructural Stormwater Management Strategies To the maximum extent practicable, these standards shall be met by incorporating nonstructural stormwater management strategies at NJAC 7:8-5.3 into the design.

6 Nonstructural Stormwater Management Strategies From NJAC 7:8-5.3 (b): Nonstructural Strategies shall: 1. Protect Areas that Provide Water Quality or are Susceptible to Erosion 2. Minimize, Break Up, and/or Disconnect Impervious Surfaces 3. Maximize Protection of Natural Drainage Features and Vegetation

7 Nonstructural Stormwater Management Strategies Nonstructural Strategies shall: 4. Minimize Decrease in TC 5. Minimize Land Disturbance, Clearing, and Grading 6. Minimize Soil Compaction 7. Provide Low Maintenance Vegetation 8. Provide Vegetated Conveyance Systems 9. Provide Pollutant Source Controls

8 Nonstructural Stormwater Management Strategies Since 2004 Issuance of SWM Rules, Defining Maximum Extent Practicable Requirement has been Difficult Question: How Much Nonstructural is Enough? Response: Nonstructural Strategies Points System

9 Nonstructural Strategies Point System (NSPS) NSPS can be Used to: Directly Demonstrate Compliance with Maximum Practicable Requirement Provide Objective Basis of Discussion of Project Compliance Provide Basis for Contention of Nonstructural Infeasibility

10 Nonstructural Strategies Point System (NSPS) NJDEP Policies for NSPS Use: Achieving Required NSPS Points Sufficient for Approval of Proposed Nonstructural Strategies Failing to Achieve Required NSPS Points CANNOT be used as Basis of Denial

11 Theoretical Basis

12 Theoretical Basis of NSPS Goal of Nonstructural Stormwater Management: Maintain Existing Site Hydrology under Proposed Site Conditions Therefore, NSPS Uses Existing Site as Basis for Determining Adequacy of Nonstructural Measures at Proposed Site

13 Theoretical Basis of NSPS Runoff Rate Base NSPS Points on Amount of Variation Between Existing and Proposed Hydrographs Over Selected Time Period? Existing Site Proposed Site Time

14 Theoretical Basis of NSPS NSPS Computes Nonstructural Site Points for Both Existing and Proposed Site Conditions NSPS Adequacy Determination Based upon Achieving Required Percentage of Existing Site Points under Proposed Conditions

15 Theoretical Basis of NSPS Required Percentage Based upon Project Size and State Planning Area Rationales: Greater Opportunity for Nonstructural Measures on Larger Sites Greater Need to Maintain Existing Hydrology in Environmentally Sensitive Zones

16 Total Project Size Larger Projects must Achieve Greater Percentage of Existing Points than Smaller Ones Typical Project Size Ranges: Less than 2 Acres 2 to 10 Acres Greater than 10 Acres Required Percentage Based upon Sliding Scale from 0.1 to 10+ Acres

17 Planning Area Projects in Higher Planning Areas must Achieve Greater Percentage of Existing Points than Ones in Lower Planning Areas NSPS Planning Areas: PA-1, 2, 3, 4, 4B, and 5 Required Percentages Shown on Data and Formulas Worksheet in NSPS

18 Required Point Ratios by Planning Area and Site Size Planning Area: PA-1 PA-2 PA-3 PA-4 PA-4B PA-5 < 2 Acres to10 Acres > 10 Acres

19 Required Points by Planning Area and Site Size 120% % of Existing Points Required 110% 100% 90% 80% 70% 60% <2 Acres 2-10 Acres >10 Acres 50% B 5 Planning Area

20 NSPS Points Existing and Proposed NSPS Points Based upon: Site Soils Existing and Proposed Land Uses/Land Covers Additional Proposed Nonstructural Measures

21 Soils and Land Uses/Covers For Same Soil: Lower Runoff Land Use/Cover Given More Points than Higher Runoff Land Use/Cover For Same Land Use/Cover: More Pervious Soils Given More Points than Less Pervious Soils

22 NSPS Points for HSG A Soils Land Use/Cover NSPS Points Indigenous Woods 700 Meadow 650 Lawn 500 Directly Connected Impervious 0

23 NSPS Points for Indigenous Woods HSG NSPS Points A 700 B 463 C 322 D 253

24 Existing Soils and Uses/Covers NSPS Points Based upon NRCS Curve Numbers (CNs) for Various Soils and Land Uses/Land Covers Complete Table of NSPS Points for Soils and Land Uses/Covers on Data and Formulas Worksheet in NSPS

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26 Additional Nonstructural Measures 1. Amount of Impervious Cover Related Strategy: Minimize, Break Up, and/or Disconnect Impervious Surfaces 2. Amount of Disturbance Related Strategy: Minimize Land Disturbance, Clearing, and Grading 3. Extent of Vegetated Swales Related Strategy: Provide Vegetated Conveyance Systems

27 Additional Nonstructural Measures 4. Clustering of Residential Lots Related Strategy: Minimize Land Disturbance, Clearing, and Grading 5. Lawn Grading with Lightweight Equipment Related Strategy: Minimize Soil Compaction

28 NSPS Program Input

29 Project Name and Description

30 Step 1 Basic Site Information Total Site Area Planning Areas

31 Step 2 Existing Site Conditions Total Existing Site Points

32 Step 2 Existing Site Conditions Most Land Use/Cover Categories from TR-55 Six Additional NSPS Categories: Wetlands and Stream Buffers Woods Planted Ponds, Lakes, and Open Waters Porous and Permeable Paving Two Unconnected Impervious Areas

33 Step 3 Proposed Site Conditions

34 Step 3 Proposed Site Conditions 2. Proposed Impervious Cover: Select Table Computed on Maximum Allowable Impervious Cover Table

35 Maximum Impervious Cover Table

36 Step 3 Proposed Site Conditions 3. Proposed Site Disturbance: 4. Proposed Vegetated Conveyance:

37 Step 3 Proposed Site Conditions 5. Clustering: 6. Soil Compaction:

38 NSPS Results

39 NSPS Results Total Proposed Site Points Proposed to Existing Points Ratio Required Points Ratio NSPS Results

40 NSPS Results If Required NSPS Points Ratio Achieved: Proposed Nonstructural Measures are Adequate If Required NSPS Points Ration Not Achieved: Further Review of Proposed Nonstructural Measures is Necessary

41 Nonstructural Strategies Point System (NSPS) NSPS Used Successfully Since 2006 to Address Maximum Extent Practicable Requirement NSPS Used from Project Planning to Final Design NSPS Used to Teach and Promote Awareness of Nonstructural SWM New Version Expected by End of 2011

42 More Information at:

43 Joseph J. Skupien, PE, PP President 1108 Old York Road P.O. Box 727 Ringoes, New Jersey Phone: Fax: