The Antrim Township Board of Supervisors finds that:
A. 
Inadequate management of accelerated stormwater runoff resulting from development throughout a watershed increases flood flows and velocities, contributes to erosion and sedimentation, overtaxes the carrying capacity of existing streams and storm sewers, greatly increases the cost of public facilities to convey and manage stormwater, undermines floodplain management and flood reduction efforts in upstream and downstream communities, reduces groundwater recharge, and threatens public health and safety.
B. 
A comprehensive program of stormwater management, including reasonable regulation of development and activities causing accelerated erosion, is fundamental to the public health, safety, welfare and the protection of the people of the municipality and all the people of the commonwealth, their resources, and the environment.
The purpose of this chapter is to promote the public health, safety and welfare by minimizing damages described in the previous section of this chapter through provisions designed to:
A. 
Manage accelerated runoff and erosion and sedimentation problems at their source by regulating activities that cause such problems.
B. 
Utilize and preserve the existing natural drainage systems.
C. 
Encourage recharge of groundwater where appropriate and prevent degradation of groundwater quality.
D. 
Maintain existing flows and quality of streams and watercourses in Antrim Township and the existing regional watersheds.
E. 
Preserve the flood-carrying capacity of streams.
F. 
Provide proper maintenance of all permanent stormwater management facilities that are constructed in Antrim Township and existing regional watersheds.
G. 
Provide performance standards and design criteria for stormwater management and planning within Antrim Township and the existing regional watersheds.
The following activities are defined as "regulated activities" and shall be regulated by this chapter:
A. 
Land development.
B. 
Subdivision.
C. 
Construction of new or additional impervious or semipervious surfaces (driveways, parking lots, etc.)
D. 
Construction of new buildings or additions to existing buildings.
E. 
Diversion or piping of any natural or man-made stream channel.
F. 
Installation of stormwater management facilities or appurtenances thereto.
G. 
Any activity requiring that a land development or subdivision plan (as defined in Chapter 125) be filed as required by Chapter 125.
A. 
Regulated activities that meet the exemption criteria in the following table may be eligible for an exemption from the requirements of Article III of this chapter, subject to a review by the Township Engineer and at the sole discretion of the Township Supervisors. Requests for exemptions shall be submitted in writing for review by the Township and shall clearly identify the justification and basis for the request. The exemption criteria shall apply to all regulated activities proposing construction of impervious surfaces after the effective date of this chapter. Regulated activities related to commercial and/or industrial development shall not be eligible for exemptions. The total impervious surface area at a site shall be calculated for the area inclusive of both existing and proposed impervious surfaces. Gravel and stone areas shall be included in the impervious area calculation but can be reduced according to the area reduction factors and sample calculation provided in Exhibit 2, Figure B-1.[1] When subdivision is proposed, the impervious area calculation shall be applied to the entire parent tract (not individual parcels) even if the development is proposed in phases. The date of adoption of this chapter shall be the starting point from which to consider tracts as parent tracts for which impervious areas shall be inclusively considered.
Stormwater Management Exemption Criteria
Total Parcel Size
(acres)
Maximum Impervious Area Exemption
(square feet)
Less than or equal to 1/4
2,500
1/4 to 1
5,000
1 to 2
10,000
2 to 5
15,000
More than 5
20,000
[1]
Editor's Note: Figure B-1 is included at the end of this chapter.
B. 
Requests for exemption shall be reviewed by the Board of Supervisors on an individual site basis using the criteria outlined in this section. An exemption shall not relieve the applicant from implementing any measures that would be necessary to protect the public health, safety, welfare, property, the resources of the people and/or the environment. Protective measures shall be required for proposed conditions, including, but not limited to, direct discharge of concentrated stormwater flows onto adjoining and/or adjacent properties.