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BMP Selection

BMP selection is the stage where the project team matches the site evidence chain to the BMPs that can actually satisfy the applicable NJAC and BMP Manual standards. In the live source set, that means screening candidate practices against the governing Tables 5-1, 5-2, and the applicable BMP chapters before detailed sizing starts.

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

Selection Logic

The current source-backed selection sequence is simpler than many of the older narrative summaries:

  • start with the standards that apply to the project: recharge, runoff quality, runoff quantity, and, for the 2026 rules, volumetric reduction
  • determine whether the proposed strategy depends on infiltration into subsoil, because that immediately triggers Chapter 12 soil-testing and Chapter 13 hydraulic-impact review
  • identify which BMP tables and source chapters are actually available under the governing NJAC subsection
  • narrow the shortlist to BMPs whose chapter-level constraints fit the site

This is why BMP selection cannot be separated from the soil, SHWT, and hydraulic-impact work done earlier in the workflow.

What the Source Set Supports

The enrolled source set supports these working rules:

  • recharge and runoff-quality selection starts with the BMPs and alternatives allowed by N.J.A.C. 7:8-5.3(b)
  • runoff-quantity selection uses the BMP tables and exception structure in N.J.A.C. 7:8-5.3(c)-(d)
  • the 2026 volumetric-reduction pathway in N.J.A.C. 7:8-5.6(d) and BMP Manual Chapter 14 makes GI retention a first-order selection issue rather than a late-stage afterthought
  • infiltration-dependent BMPs only stay on the shortlist when Chapter 12 and Chapter 13 support them

Multi-BMP coordination

Selection has to stay explicit once one BMP is not enough. For runoff-quality treatment trains, N.J.A.C. 7:8-5.5(e) requires the series-removal formula instead of adding TSS percentages by hand.

For groundwater-recharge solutions that split runoff between multiple recharge BMPs, BMP Manual Chapter 6 requires the designer to assign each BMP its own exact Aimp and Vdef rather than carrying the NJGRS default sitewide values through the whole design.

That means the selection output should name not just the BMP family, but also which runoff area and which portion of the recharge deficit each BMP is intended to handle.

Selection Outputs

The useful deliverable from this stage is a source-backed shortlist, not just a preferred BMP label. At minimum, the stage should end with:

  • the governing NJAC path for each selected BMP family
  • confirmation of whether infiltration-dependent options remain feasible
  • a clear note on whether one BMP is enough or whether a treatment train is still needed
  • a record of which routes were rejected because the site evidence or table logic did not support them

Practical Shortlist Questions

The page-level decision questions that remain stable across the live source set are:

  1. Does the selected BMP chapter actually authorize this practice for the needed standard?
  2. Does the site investigation support infiltration, recharge use, or only lined / underdrained treatment?
  3. Can one BMP satisfy the required standards, or does the project need more than one BMP working together?
  4. Is the selected BMP still within the chapter-scale limits for drainage area, drain time, SHWT separation, and maintenance burden?