There are a few additional design considerations that will need to be taken into account when preparing a Stormwater Pollution Prevention Plan for Residential Subdivisions, particularly those developing subdivisions.
Residential Subdivision Guidance
Residential Disturbance Formula
Amount of Disturbance = 2[Max Restricted Building Size][Number of Lots] + Right of Way Areas
*Max Restricted Building Size = Maximum
Disturbed Area per Lot (Acres)
Residential Note for Plans
The site is not to be mass-graded. Only 2 times the footprint is to be cleared as the lots are developed. The assumed disturbance on each lot is _____ sq. ft.”
One of those considerations that will affect the stormwater management plan of a Residential Subdivision Projects is the decision if the subdivision is to be mass graded or not. If the decision is made for the site not to be mass graded the following steps must be implemented while developing the SWPPP:
- Determine the Disturbed Area based off the Residential Disturbance Formula provided in the Residential Subdivision Guidance to the right.
- Include a note on the plans that states the site is not to be mass graded and the amount of disturbance allotted for each lot. (See Residential Guidance)
- Provide a Residential Lot Detail that illustrates how much of the lot may be disturbed in addition to the placement of BMPs.
Developers may decide that they do not wish to include any of the residential lot’s disturbed area in their NPDES Permit Coverage when deciding to not mass grade the site. In this case, the Max Restricted Building Size value would be Zero (0) in the above Residential Disturbance Formula and each individual lot would have to apply for NPDES coverage under a separate permit number but part of a Larger Common Plan (LCP).
Bureau of Water . Phone: (803) 898-4300 . Fax: (803) 898-3795 .