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Volumetric Reduction Credit

In the live source corpus, the governing authority for volumetric reduction is the 2026 subsection at N.J.A.C. 7:8-5.6(d), supported by BMP Manual Chapter 14. This page keeps the familiar authored label "Volumetric Reduction Credit," but the underlying source-backed standard is the rule's volumetric-reduction requirement.

Structured citation evidence for this page lives in the sibling claim manifest.

Regulatory Summary

N.J.A.C. 7:8-5.6(d) requires the design engineer to demonstrate that a major development meets the minimum volumetric-reduction standard.

The first path in the subsection is retention of the Water Quality Design Storm through green infrastructure BMPs from Table 5-1 and Table 5-2, unless the technically-impracticable alternative in the subsection applies.

Offsite option

The 2026 rule also allows all or part of the volumetric-reduction standard to be met through offsite impervious-surface removal or offsite retention, subject to specific conditions:

  • the offsite work must remain within the same HUC-14 unless the public-transportation exception applies
  • the application must include enough information and property-owner permission to review the offsite work together with the project
  • the offsite work must be constructed prior to, or concurrent with, the major development

Chapter 14 Role

BMP Manual Chapter 14 exists to explain and work through the new volumetric-reduction standard. In the live source set, Chapter 14 ties the rule text to practical design paths such as:

  • onsite retention of the WQDS
  • technically-impracticable alternatives that use peak-flow and hydrograph-duration demonstrations
  • offsite impervious-surface removal or offsite retention

That makes Chapter 14 the technical-method chapter, while N.J.A.C. 7:8-5.6(d) remains the governing rule text.

Engineering Interpretation

The safest authored summary is:

  1. Start with N.J.A.C. 7:8-5.6(d), not a free-floating "VRC" concept.
  2. Determine whether the site can retain the WQDS through eligible BMPs.
  3. If not, evaluate the technically-impracticable path and, where allowed, the offsite options described in the rule.

The live source set supports volumetric reduction as a real 2026 compliance layer, but it does not support treating it as a standalone legacy section outside N.J.A.C. 7:8-5.6(d).

Cross References