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Design Workflow

Workflow Module

The Design Workflow module guides engineers through the staged process of translating regulatory requirements into a compliant, site-appropriate stormwater management system.

Reference: [Agents/14_stormwater_design_decision_trees.md](https://github.com/InfusedChooch/Opal_Rev1/blob/main/Agents/14_stormwater_design_decision_trees.md)

Workflow Stages

Stage Purpose Key Outputs
1. Site Constraints Analysis Gather site data and identify feasibility limits Soil report, SHWT, drainage map, constraint summary
2. Hydrologic Analysis Quantify pre/post development hydrology CN values, WQV, recharge deficit, peak flows
3. BMP Selection Select BMP candidates filtered by constraints BMP alternatives, GI/Non-GI classification
4. BMP Sizing Size BMPs to meet design storm standards Storage volumes, footprints, grading plans
5. Maintenance Planning Establish long-term O&M requirements Maintenance agreement, inspection schedule

Engineering Reasoning Chain

Regulation -> BMP Strategy -> Site Constraints -> [This Workflow]

Each stage output feeds the next. Document decisions at each stage for regulatory traceability.

How Stages Connect to Other Modules

  • Stage 1 draws from Engineering Constraints to identify site limits
  • Stage 2 applies standards from the Regulatory Explorer
  • Stage 3 filters candidates from the BMP Library
  • Stage 4 uses design criteria from individual BMP pages
  • Stage 5 references maintenance tabs on each BMP page

Source Alignment (Auto-Synced Draft)

Auto-synced from Outs/Phase1C_Engineering_Content.md -> "4.1 Changes in Design Workflow" on 2026-03-05. Manual review required before release.

The transition from 2023 to 2026 standards requires several specific adjustments in how stormwater design is sequenced:

  1. GI Feasibility Analysis moves earlier. The 2026 framework requires documented GI feasibility (soil investigation, SHWT mapping, setback analysis, hotspot screening) before proposing any Non-GI BMP alternative for the water quality standard. This is a pre-design task, not a permit-response task. Engineering scope of work for major projects should include a GI feasibility phase scoped to the new soil investigation protocol.

  2. Volumetric reduction accounting is now a distinct calculation step. Under the 2026 standard, the design sequence for water quality compliance is: (a) calculate WQV; (b) design proposed GI BMP; (c) calculate VRv per Chapter 14; (d) compare VRv to WQV; (e) if residual exists, size a compliant Non-GI BMP for the residual. This is a more structured and multi-step workflow than the 2023 approach of sizing a single BMP to the WQV.

  3. Soil borings are required for all recharge-based BMPs. Under the 2026 soil investigation protocol, desktop assessment is insufficient for design confirmation. Site investigation must be scheduled into the project timeline before final BMP sizing.

  4. CN table updates require verification for existing designs. Projects designed under 2023 standards that are being updated or revised must confirm whether WQV and recharge calculations use the 2026 CN and Table 6-1 values, as updated values may alter BMP sizing even if the site design is otherwise unchanged.