How are single lot improvements such as structures, home additions, patios and driveways permitted to ensure proper stormwater management?

A Stormwater Management (SWM) Permit Application must be completed for any improvements that will result in 100 square feet or more of new impervious (water cannot get through) surface.  Examples would include sheds, home additions, patios and driveways. A copy of our Stormwater Management Permit Application can be obtained by clicking the following link:

SWM Permit Application

The SWM application is typically completed at the time a building permit application is completed. Following the completion of a SWM application, Township Staff will utilize the following criteria in reviewing the application and information provided as part of the building permit application.


  • Will the project result in 1000 square feet or more of new impervious surface?
    • Yes, the applicant will be required to provide a SWM Site Plan which will require the services of a qualified professional. The completed SWM Site Plan will then need to be reviewed and approved by the Township Engineer before Township Staff can issue a SWM Permit.
    • No, Township Staff will review the SWM Application and will work with the Property Owner and/or Contractor to determine the Best Management Practice (BMP) to be used for managing rainwater runoff from the new impervious surface.


  • Does the project site qualify as a Disconnected Impervious Area (DIA)?
    • Yes, there are adequate on-site conditions to ensure that runoff from the new impervious surface will infiltrate into the soil and not leave the property. A slope of less than 5%, no more than 500 SF of roof drainage discharged to any one point, and a flow path greater than 75 feet would constitute adequate on-site conditions. If the site is approved for a DIA, the completion of an SWM Permit will not be required.
    • No, some form of Structural BMP will be required such as infiltration beds, infiltration trenches, and/or Rain Gardens. The completion of a SWM Permit will be required.


A copy of our SWM Small Project Guide can be obtained by clicking on the following link:

SWM Small Project Guide

Our SWM Small Project Guide describes the on-site conditions necessary to qualify for a Disconnected Impervious Area (DIA) along with specifications and diagrams of the structural BMPs (beds, trenches, and Rain Gardens) that Township Staff can approve and permit.

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