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Extended Detention Basin

Extended detention basins in the live source corpus are governed by BMP Manual Chapter 11.2. This page now stays with that source-backed reading: a non-GI storage-and-drawdown BMP whose value comes from controlled release and basin management rather than from infiltration credit.

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

Overview

In the live source set, extended detention is fundamentally a storage-and-drawdown basin concept. It should not be described as GI by default, and it should not be treated as though detention alone creates recharge or volumetric-reduction credit.

Source Mapping

The live citations layer resolves this route directly to the following canonical source bundles.

  • Route type: canonical
  • 2023 source bundle: Chapter 11.2 (2023_BMP_11_2) - Extended Detention Basins (Non-GI)
  • 2026 source bundle: Chapter 11.2 (2026_BMP_11_2) - Extended Detention Basins (Non-GI)

Key verified claims already tied to this page manifest: - Extended detention basins are source-backed through Chapter 11.2. - Extended detention basins remain non-GI storage-and-release BMPs in the live source set. - Extended-detention maintenance stays tied to forebay, outlet, sediment, and structural component condition.

Design Criteria

The reconciled design criteria below come from the live crosswalk and page-level claim set, not from the older narrative snapshot.

This route does not have a dedicated parameter table in the crosswalk, so the controlling criteria stay tied to the verified claims and canonical source-bundle mapping below.

Source-backed criteria that still control this route: - Extended detention basins are source-backed through Chapter 11.2. - Extended detention basins remain non-GI storage-and-release BMPs in the live source set. - Extended-detention maintenance stays tied to forebay, outlet, sediment, and structural component condition.

Siting Constraints

The current source-backed siting review should focus on:

  • whether the project has enough area and access to operate a detention-basin footprint correctly
  • whether the design is overstating infiltration or GI benefit that the source chapter does not actually provide
  • whether outlet control, structural component condition, and maintenance access are being treated as core design issues

Maintenance

Maintenance remains basin-centered:

  • protect forebay and sediment-storage capacity
  • keep outlet and drawdown controls working
  • monitor structural component and basin condition as operating infrastructure

Source Bundles

Use these source bundles when checking the live extracted text or paired OCR evidence:

  • 2023 bundle: Chapter 11.2 (2023_BMP_11_2) - Extended Detention Basins (Non-GI)
  • 2026 bundle: Chapter 11.2 (2026_BMP_11_2) - Extended Detention Basins (Non-GI)