The NJDEP has proposed changes to its stormwater rules that would require green infrastructure practices for all major developments. Major developments are defined as projects disturbing one acre or more of land, increasing impervious surface by a quarter acre, or involving a quarter acre of regulated motor vehicle surfaces. The proposed changes would modify standards to mandate green infrastructure for groundwater recharge, stormwater runoff quality and quantity. It would also update definitions and provide guidance to municipalities on mitigation and community stormwater basins.

1. NJDEP’S NEW PROPOSED STORMWATER RULE
Michele Adams, PE LEED AP
Meliora Design
michelea@melioradesign.com

2. Proposed changes published December 3, 2018
https://www.nj.gov/dep/rules/notices/20181203a.html
Written comments until February 1, 2019
This is the first of additional updates and changes the
Department is considering.
TIMELINE

3. REMOVED:
Identify non-structural stormwater management strategies and
require that they be incorporated into the design of major
development to the “maximum extent practicable”
N.J.A.C. 7:8-5.3
ADDED:
Minimum Standards for groundwater recharge, stormwater runoff
quality, and stormwater runoff quantity shall be met using green
infrastructure.
Updating definitions, minor changes, and cross-references
KEY PROPOSED CHANGES FOR MAJOR DEVELOPMENTS

4. APPLICABLE TO MAJOR DEVELOPMENT
MAJOR DEVELOPMENT
• Disturbing 1 or more acres of land or
• Increasing Impervious by one quarter acre or more
• One-quarter acre or more of “regulated motor vehicle surfaces”
• Government projects included

5. MODIFIED AND ADDED DEFINITIONS
GREEN INFRASTRUCTURE
Manages Stormwater close to its source by:
1. Treating stormwater runoff through infiltration into subsoil
2. Treating stormwater runoff through filtration by vegetation or soil
3. Storing stormwater runoff for reuse

6. Porous Paving
Conventional
Paving
“The use of Green Infrastructure BMPs such as Pervious
Paving, Infiltration Basins, and Bioretention Systems will
more effectively achieve the Department’s goals under
existing rules.”

7. Pervious Paving
Pervious Paving
Conventional Paving

8. Infiltration Basins

9. Bioretention

10. • Groundwater Recharge
• Retain 100% average annual preconstruction GW recharge or
• Recharge 2-year net increase, pre- to post-development
• Stormwater Runoff Quantity
• Maintain 2-, 10-, and 100-year pre- to post hydrographs
• Maintain 2-, 10-, and 100-year pre- to post peak rates and no downstream
damage
• Peak rates reduced 50%, 75%, and 80% for 2-, 10-, and 100 year events
• Tidal Hazard areas – downstream impacts
MINIMUM STANDARDS FOR GROUNDWATER RECHARGE
AND STORMWATER RUNOFF QUANTITY UNCHANGED

11. “applicable when the major development results in an increase of
¼ acre or more of regulated vehicle surface”
• 1.25-inch water quality design storm
MINIMUM STANDARD FOR STORMWATER RUNOFF
QUALITY MODIFIED AS FOLLOWS:

12. OTHER MODIFIED AND ADDED DEFINITIONS
CONTRIBUTARY DRAINAGE AREA
Area from which stormwater runoff drains to a stormwater management
measure, not including the area of the stormwater management area itself.

13. OTHER MODIFIED AND ADDED DEFINITIONS
MOTOR VEHICLE SURFACE
• Used by Motor Vehicles
• Pervious or Impervious
REGULATED IMPERVIOUS SURFACE (new)
• Net increase in impervious
• Total area of impervious surface collected by new stormwater system
• Total area of impervious surface to be collected by an existing system
• Total area of impervious surface collected by an existing stormwater
conveyance system where the capacity of that system is increased.
OTHERS
• Tidal Flood Hazard Area, Water Control Structure, Community Basin,
Disturbance

15. (Continued)

18. • Guidance to municipalities on mitigation (offsetting)
• Guidance on Community Basins for municipalities to address
flooding and CSOs
OTHER PROPOSED CHANGES FOR MAJOR DEVELOPMENTS

19. SOCIAL ECONOMIC ENVIRONMENTAL BENEFITS
• Reduce Flooding
• Improve Water Quality
• Increasing Groundwater
Recharge
• Protecting Stream
Channel Integrity
• Reducing Erosion
• Maintaining Adequacy of
Bridges and Culverts
• Improving Air Quality
• Reducing Heat Island
• Decreasing Energy Use
A Triple Bottom
Line approach

21. Questions?