Township of Upper Makefield, PA Stormwater Management Site Plan Requirements

A feasibility analysis that evaluates the potential application of infiltration, flow attenuation, bioretention, wetland, or wet pond BMPs must be submitted with the stormwater management plans required in Article IV, including those developments not intending the use of such facilities. This analysis shall provide:

(a)

A general assessment of the anticipated additional runoff based on the design storm and postdevelopment condition and utilizing the calculation procedures required in § 28B-304;

(b)

Indication of drainage areas on the development site resulting in impervious, pervious, and rooftop runoff;

(c)

Indication of type of land use (residential, nonresidential) generating the impervious surface runoff;

(d)

Delineation of soils on the site from the NRCS, Soil Survey of Bucks and Philadelphia Counties and on-site soil study. Soil study shall be conducted by a soil scientist and shall include sufficient probes/deep holes to evaluate application of BMPs;

(e)

Indication of soils generally suitable for infiltration and/or wet pond/artificial wetland BMPs as shown in the table entitled: "General Soil Suitability for Infiltration, Wet Pond and Artificial Wetland Best Management Practices With Consideration to Runoff Point of Origin and Land Use Type," including specification of those soils requiring modifications;

(f)

Calculated acreage of suitable soils for infiltration BMPs and wet pond or artificial wetland BMPs and percentage of suitable soils based on total site acreage;

(g)

Calculated acreage of suitable soils for infiltration BMPs and wet pond or artificial wetland BMPs made unavailable due to proposed development layout and justification that alternative development layout which would reduce impact on suitable soil availability is unfeasible;

(h)

Analysis of potential infiltration or wet pond or artificial wetland BMPs which could be implemented to manage the projected postdevelopment runoff with consideration of suitable soil availability runoff point of and type of land use Subsection A(1)(b) and (c) and the general design standards and maintenance issues included in this chapter including an indication of how most postdevelopment runoff can be managed by these BMPs (e.g., the entire postdevelopment runoff or partial amount of runoff expressed as a percentage); and

(i)

Rationale for the decision to not proceed with implementation of infiltration BMPs or wet pond or artificial wetland BMPs such as excessive cost of implementation, insufficient soil suitability, and development constraints.

The feasibility analysis must allow the municipality to review the general soil characteristics of a site and the proposed development for that site and determine if infiltration BMPs or wet pond or artificial wetland BMPs could have been more thoroughly pursued for use by the developer. The information required in the analysis is detailed enough to determine the potential applicability of these BMPs for a proposed development, but general enough not to force a developer into incurring excessive cost associated with conducting laborious field and/or laboratory soil testing for a site which ultimately may not be suitable for infiltration or wet pond or artificial wetland BMP implementation. However, with the requirements for conducting a feasibility analysis, developers will be aware that they are expected to use these BMPs wherever possible and are required to provide adequate justification if these BMPs are not to be implemented. Essentially, all developers will be conducting feasibility analysis since such analysis would become the preliminary step in evaluating the potential for implementation of these mandatory BMPs where possible. Developers for those sites that are determined to be generally suitable from these analyses (taking into consideration the areal extent of suitable soils necessary to accommodate an infiltration or wet pond or wetland BMP for the type and size of development proposed) are required to conduct the detailed soil testing and other feasibility testing required in other sections of this chapter which contain the description and additional design criteria of these BMPs.

A detailed geologic evaluation of the project site shall be performed to determine the suitability of recharge facilities. The evaluation shall be performed by a qualified deep hole testing and infiltration testing shall be performed by a Certified Professional Soil Scientist (CPSS), Certified Professional Soil Classifier (CPSC), or a Sewage Enforcement Officer (SEO) or geologist, and, at a minimum, address soil permeability, depth to bedrock, susceptibility to sinkhole formation, and subgrade stability.

General.

General description of project including stormwater management concept for the project.

General description of permanent stormwater management techniques, including construction specifications of the materials to be used for stormwater management facilities. If BMPs other than green infrastructure methods and LID practices are proposed to achieve the volume, rate, and water quality controls of this chapter, written justification for use of these BMPs must be submitted.

Complete hydrologic, hydraulic, and structural computations for all stormwater management facilities.

Map(s) of the project area shall be submitted on twenty-four-inch-by-thirty-six-inch sheets and shall be prepared in a form that meets the requirements for recording at the offices of the Recorder of Deeds of Bucks County. The contents of the maps(s) shall include, but not be limited to:

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

Existing contours at intervals of two feet. In areas of steep slopes (greater than 25%), five-foot contours may be used.

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

(4)

Other physical features, including flood hazard boundaries, sinkholes, streams, existing drainagecourses, wetlands, areas of natural vegetation to be preserved, and the total extent of the upstream area draining through the site. A determination of site conditions in accordance with the BMP Manual.[1] A detailed site evaluation shall be completed for projects proposed in areas of carbonate geology or karst topography, and other environmentally sensitive areas, such as brownfields.

[1]

Editor's Note: see § 28B-1001C.

(5)

The locations of all existing and proposed utilities, sanitary sewers, septic systems, wells, and waterlines located on the site and/or within 50 feet of property lines.

(6)

An overlay showing soil names and boundaries. This overlay shall include a table on the map showing the recharge capabilities of each soil represented on site in inches per hour and describe their recharge or infiltration capabilities.

(7)

Proposed changes to the land surface and vegetative cover, including the type and amount of impervious area that would be added.

(8)

Proposed structures, roads, paved areas, and buildings. Where pervious pavement is proposed for parking lots, recreational facilities, nondedicated streets, or other areas, pavement construction specifications shall be noted on the plan.

(9)

Final contours at intervals at two feet. In areas of steep slopes (greater than 25%), five-foot contour intervals may be used.

(10)

The name of the development, tax parcel number(s), the name and address of the owner of the property, and the name of the individual or firm preparing the plan.

(11)

The date of submission.

(12)

A graphic and written scale of one inch equals no more than 50 feet. For tracts of 20 acres or more, the scale may be one inch equals no more than 100 feet.

(13)

A North arrow.

(14)

The total tract boundary and size, with distances marked to the nearest foot and bearings to the nearest degree, as confirmed by a professional land surveyor licensed in the commonwealth.

(15)

Existing and proposed land use(s).

(16)

A key map showing all existing man-made features beyond the property boundary that may be affected by the project.

(17)

Horizontal and vertical profiles of all open channels and storm sewer systems, including hydraulic capacity.

(18)

Overland drainage paths and path utilized to determine time of concentration.

(19)

A twenty-foot-wide access easement around all stormwater management facilities that would provide ingress to and egress from a public right-of-way.

(20)

A note on the plan indicating the location and responsibility for maintenance of stormwater management facilities that would be located off site. All off-site facilities shall meet the performance standards and design criteria specified in this chapter.

(21)

A construction detail of any improvements made to sinkholes and the location of all notes to be posted, as specified in this chapter.

(22)

A statement, signed by the landowner, acknowledging the stormwater management system to be a permanent fixture that can be altered or removed only after approval of a revised plan by the Township, which shall be recorded with the record plan and which shall be applicable to all future landowners.

(23)

The location of all erosion and sedimentation control facilities.

(24)

The following signature block for the design engineer:

(Design engineer), on this date (date of signature), has reviewed and hereby certifies that the stormwater management plan meets all design standards and criteria of Upper Makefield Township Watershed Act 167 Stormwater Management Ordinance (Delaware River South).

Supplemental information.

A written description of the following information shall be submitted.

(a)

The overall stormwater management concept for the project.

(b)

Stormwater runoff computations as specified in this chapter, or as otherwise necessary to demonstrate that the maximum practicable measures have been taken to meet the requirements of this chapter, including the recommendations and general requirements in this chapter.

(c)

Stormwater management techniques to be applied both during and after development.

(d)

Expected project time schedule.

A soil erosion and sedimentation control plan, where applicable, including all reviews and approvals, as required by PADEP and/or Bucks Conservation District.

A geologic assessment of the effects of runoff on sinkholes and carbonate/karst topography as specified in this chapter.

(4)

The effect of the project (in terms of runoff volume, water quality, and peak flow) on adjacent properties and on any existing municipal stormwater collection system that may receive runoff from the project site.

(5)

A declaration of adequacy and highway occupancy permit from the PADOT district office, when utilization of a PADOT storm drainage system is proposed.

(6)

Plan and profile drawings of all SWM BMPs, including drainage structures, pipes, open channels, and swales.

(7)

SWM site plan shall show the locations of existing and proposed on-lot wastewater facilities and water supply wells.

(8)

The SWM site plan shall include an O&M plan for all existing and proposed physical stormwater management facilities. This plan shall address long-term ownership and responsibilities for O&M as well as schedules and costs for O&M activities.

(9)

A justification must be included in the SWM site plan if BMPs other than green infrastructure methods and LID practices are proposed to achieve the volume, rate and water quality controls under this chapter.

(10)

Construction details for all stormwater management BMPs, collection systems, and appurtenances.

Stormwater management BMPs facilities.

All existing and proposed stormwater management BMPs facilities must be located on a plan and described in detail.

When groundwater recharge methods, such as seepage pits, beds, or trenches, are proposed, the locations of existing and proposed septic tank infiltration areas and wells must be shown. A separation distance of no less than 20 feet shall be provided between any septic system and any facility used for stormwater management.