the new jersey nonstructural strategies point system (nsps)...the new jersey nonstructural...

The New JerseyNonstructural Strategies

Point System(NSPS)

2011 Low Impact Development Symposium

Storm Water Management Consulting, LLC


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


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


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.”


Nonstructural StormwaterManagement 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.”



From NJAC 7:8-5.3 (b):

Nonstructural Strategies shall:1. Protect Areas that Provide Water Quality

or are Susceptible to Erosion2. Minimize, Break Up, and/or Disconnect

Impervious Surfaces3. Maximize Protection of Natural Drainage

Features and Vegetation



Nonstructural Strategies shall:4. Minimize Decrease in TC5. Minimize Land Disturbance, Clearing,

and Grading6. Minimize Soil Compaction7. Provide Low Maintenance Vegetation8. Provide Vegetated Conveyance Systems9. Provide Pollutant Source Controls


Nonstructural StormwaterManagement 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


Nonstructural StrategiesPoint 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



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


Theoretical Basis


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



Time

Run

off R

ate

Existing Site

Proposed Site

Base NSPS Pointson Amount of VariationBetween Existing and

Proposed HydrographsOver Selected Time

Period?



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



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


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


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


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 0.60 0.75 0.80 0.84 0.89 0.95

2 to10 Acres 0.69 0.84 0.89 0.93 0.98 1.04

> 10 Acres 0.80 0.95 1.00 1.04 1.09 1.15


Required Points by Planning Area and Site Size

50%

60%

70%

80%

90%

100%

110%

120%

Planning Area

% o

f Exi

stin

g Po

ints

Req

uire

d

<2 Acres2-10 Acres>10 Acres

1 2 3 4 54B


NSPS Points

Existing and Proposed NSPS Points Based upon: Site Soils Existing and Proposed Land

Uses/Land Covers Additional Proposed Nonstructural

Measures


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


NSPS Points for HSG A Soils

Land Use/Cover NSPS Points

Indigenous Woods 700

Meadow 650

Lawn 500

Directly Connected Impervious

0


NSPS Points for Indigenous Woods

HSG NSPS Points

A 700

B 463

C 322

D 253


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


Additional Nonstructural Measures

1. Amount of Impervious Cover Related Strategy: Minimize, Break Up,

and/or Disconnect Impervious Surfaces2. Amount of Disturbance Related Strategy: Minimize Land

Disturbance, Clearing, and Grading3. Extent of Vegetated Swales Related Strategy: Provide Vegetated

Conveyance Systems


Additional Nonstructural Measures

4. Clustering of Residential Lots Related Strategy: Minimize Land

Disturbance, Clearing, and Grading5. Lawn Grading with Lightweight

Equipment Related Strategy: Minimize Soil

Compaction


NSPS Program Input


Project Name and Description


Step 1 – Basic Site Information

Total Site Area

Planning Areas


Step 2 – Existing Site Conditions

Total Existing Site Points


Step 2 – Existing Site Conditions

Most Land Use/Cover Categories from TR-55 Six Additional NSPS Categories:Wetlands and Stream BuffersWoods – Planted Ponds, Lakes, and Open Waters Porous and Permeable Paving Two Unconnected Impervious Areas


Step 3 – Proposed Site Conditions



Computed on Maximum AllowableImpervious Cover Table

2. Proposed Impervious Cover:Select “Table”


Maximum Impervious Cover Table



3. Proposed Site Disturbance:

4. Proposed Vegetated Conveyance:



5. Clustering:

6. Soil Compaction:


NSPS Results


NSPS Results

NSPS Results

Total Proposed Site Points

Required Points Ratio

Proposed to Existing Points Ratio


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”


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



More Information at:www.njstormwater.org

Joseph J. Skupien, PE, PPPresident

Storm Water Management Consulting, LLC1108 Old York Road

P.O. Box 727Ringoes, New Jersey 08551

Phone: 908-806-7700Fax: 908-806-7721

[email protected]


the new jersey nonstructural strategies point system (nsps)...the new jersey nonstructural...

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