§ 383-20. Drainage plan contents.

The following items shall be included in the drainage plan:

A. 

General.

(1) 

General description of project.

(2) 

General description of proposed permanent stormwater controls.

(3) 

The name and address of the project site, the name and address of the owner of the property and the name of the individual or firm preparing the drainage plan.

B. 

Map(s) of the project area showing:

(1) 

The location of the project relative to highways, municipalities or other identifiable landmarks.

(2) 

Existing contours at intervals of two feet. In areas of steep slopes (greater than 15%), five-foot contour intervals may be used. Off-site drainage areas impacting the project including topographic detail.

(3) 

Streams, lakes, ponds or other bodies of water within the project area.

(4) 

Other features including flood hazard boundaries, existing drainage swales, wetlands, closed depressions, sinkholes and areas of natural vegetation to be preserved.

(5) 

Locations of proposed underground utilities, sewers and water lines. The locations of all existing and proposed utilities, sanitary sewers and water lines within 50 feet of property lines of the project site.

(6) 

An overlay showing soil types and boundaries based on the Lehigh or Northampton County Soil Survey, as applicable, latest edition. Any hydric soils present on the site should be identified as such.

(7) 

An overlay showing geologic types, boundaries and any special geologic features present on the site.

(8) 

Proposed changes to land surface and vegetative cover.

(9) 

Proposed structures, roads, paved areas and buildings.

(10) 

Final contours at intervals of two feet. In areas of steep slopes (greater than 15%), five-foot contour intervals may be used.

(11) 

Stormwater management district boundaries applicable to the site.

(12) 

Clear identification of the location and nature of permanent stormwater BMPs.

(13) 

An adequate access easement around all stormwater BMPs that would provide municipal ingress to and egress from a public right-of-way.

(14) 

A schematic showing all tributaries contributing flow to the site and all existing man-made features beyond the property boundary that would be affected by the project.

(15) 

The location of all public water supply wells within 400 feet of the project and all private water supply wells within 100 feet of the project.

C. 

Stormwater management controls and BMPs.

(1) 

All stormwater management controls and BMPs shall be shown on a map and described, including:

(a) 

Groundwater recharge methods such as seepage pits, beds or trenches. When these structures are used, the locations of septic tank infiltration areas and wells shall be shown.

(b) 

Other control devices or methods such as rooftop storage, semipervious paving materials, grass swales, parking lot ponding, vegetated strips, detention or retention ponds, storm sewers, etc.

(2) 

All calculations, assumptions and criteria used in the design of the BMPs shall be shown.

(3) 

All site testing data used to determine the feasibility of infiltration on a site.

(4) 

All details and specifications for the construction of the stormwater management controls and BMPs.

D. 

The BMP Operations and Management Plan, as required in Article VII, describing how each permanent stormwater BMP will be operated and maintained and the identity of the person(s) responsible for operations and maintenance. A statement must be included, signed by the landowner, acknowledging that the stormwater BMPs are fixtures that cannot be altered or removed without approval by the municipality.

E. 

Environmental resources site design assessment.

(1) 

An Environmental Resources Site Design Assessment that describes the following:

(a) 

The extent to which the proposed grading and impervious cover avoid disturbance of significant environmental resources and preserve existing site hydrology.

(b) 

An assessment of whether alternative grading and impervious cover site design could lessen the disturbance of significant environmental resources and/or make better use of the site hydrologic resources.

(c) 

A description of how the proposed stormwater management controls and BMPs serve to mitigate any adverse impacts on environmental resources on the site.

(2) 

Significant environmental resources considered in the site design assessment include, but are not limited to, steep slopes, ponds, lakes, streams, wetlands, hydric soils, floodplains, riparian vegetation, native vegetation and special geologic features.