A Model for the Local Stormwater Management Plan Review Process
At any new development site, the design engineer will need to prepare both a "concept" plan, and a final stormwater management plan. The concept plan identifies basic site information, locations of proposed development features, and preliminary locations and sizing of stormwater treatment practices. The final plan provides more detailed design information for stormwater practices, and includes much greater detail in terms of hydrologic conditions and site features. The concept plan is also typically reviewed in conjunction with a preliminary plan or site plan. The accompanying figure summarizes important stormwater management plan review elements. The process can be explained in seven steps.
Step 1. What permits are required for this site, and what waivers are applicable?
In this step, the design engineer applies for appropriate permits, and requests waivers where available. A more detailed description of this process is described in the Post-Construction Stormwater Ordinance.
Step 2. Does the plan incorporate Better Site Design techniques to meet stormwater objectives?
In this step, a reviewer evaluates the site plan to see if the designer used available opportunities to meet stormwater objectives using innovative site design techniques. Click here for a Better Site Design Checklist that an applicant can use to demonstrate how these techniques were incorporated into the site plan. In some communities, these techniques are directly integrated into the stormwater planning process through the use of Stormwater Credits.
Step 3. Are the selected practices appropriate for this site?
In both the concept plan and final plan stages, the reviewer needs to ensure that the practices selected for the site are appropriate. The Stormwater Selection Criteria section of the Manual Builder provides guidance on how to locate practices on a site.
Step 4. Are the practices designed to meet minimum performance criteria?
In this step, the reviewer also needs to evaluate if the site plan as presented captures the necessary volume to meet the groundwater recharge, water quality, stream channel protection, and flood control goals outlined in the manual. The Sizing Criteria section outlines options for sizing stormwater treatment practices. The reviewer also evaluates design information in the plan to determine if the practices meet minimum design standards. The Performance Criteria section details specific requirements for each STP option.
Step 5. Does the Plan meet other resource protection requirements?
New developments are often subject to local, state, or federal regulations in addition to stormwater management, and the stormwater review process needs to be integrated with review for these other resource protection measures. Click here for example ordinances for:
Step 6. Do the As-Built Designs satisfy construction specifications?
During and after construction, inspectors determine if the plan is implemented adequately. The Manual Builder includes Construction Specifications, which provide detailed information on construction materials and techniques, as well as a Construction Inspection Checklist for each practice type.
Step 7. Are provisions for long-term maintenance adequate?
The stormwater management plan should provide for long-term maintenance of stormwater treatment practices. These maintenance measures may be assumed by the local government, or by the land owner. Click here to obtain Maintenance Inspection Checklists for each STP group.