Borough of Downingtown, PA Stormwater Management (SWM) Site Plan Requirements

A general description of the proposed project.

A listing of all regulatory approvals required for the proposed project and the status of the review and approval process for each. Final approval or adequacy letters must be submitted to the municipality prior to (or as a condition of) the municipality's issuing final approval of the SWM site plan. Proof of application or documentation of required permits or approvals for the programs listed below shall be part of the SWM site plan, if applicable:

NPDES permit for stormwater discharges associated with construction activities;

PADEP permits as needed:

PADEP joint permit application;

Chapter 105 (Dam Safety and Waterway Management);[1]

Editor's Note: See 25 Pa. Code Chapter 105.

[3]

Chapter 106 (Floodplain Management);[2]

Editor's Note: See 25 Pa. Code Chapter 106.

PennDOT highway occupancy permit;

Erosion and sediment control plan letter of adequacy; and

Any other permit under applicable state or federal regulations.

A statement, signed by the applicant, acknowledging that any revision to the approved SWM site plan shall be submitted to and approved by the municipality, and that a revised erosion and sediment control plan shall be submitted to, and approved by, the Conservation District or municipality (as applicable) for a determination of adequacy prior to construction of the revised features.

The following signature block signed and sealed by the qualified licensed professional responsible for the preparation of the SWM site plan:

"I (name), on this date (date of signature), hereby certify to the best of my knowledge that the SWM site plan meets all design standards and criteria of the Borough of Downingtown Ordinance No. 2023-01, Stormwater Management Ordinance." [Note: Include signature, name, discipline of professional license, and license stamp or seal here]

The following signature block for the municipality:

"On behalf of [Municipality name], (Municipal official or designee), on this date [Signature date], has reviewed and hereby certifies to the best of my knowledge that the SWM site plan meets all design standards and criteria of the Municipal Ordinance No. 2023-01."

Maps or plan sheets. Map(s) or plan sheets of the site shall be submitted on minimum twenty-four-inch by thirty-six-inch sheets and shall be prepared in a form that meets the requirements for recording at the Chester County Office of the Recorder of Deeds and the requirements of the operation and maintenance (O&M) plan and O&M agreement (Article VII). If the SALDO has additional or more stringent criteria than this chapter, then the SALDO criteria shall also apply. Unless otherwise approved by the Municipal Engineer, the contents of the maps or plan sheets shall include, but not be limited to:

A location map, with a scale of one inch equals 2,000 feet or greater, showing the site location relative to highways, municipal boundaries, or other identifiable landmarks.

The name of the project, tax parcel number(s), and the names, addresses and phone numbers of the owner of the property, the applicant, and firm preparing the plan.

Signature and seal of the qualified licensed professional(s) responsible for preparation of the maps and plan sheets.

The date of SWM site plan submission and revision dates, as applicable.

A graphic and written scale of one inch equals no more than 50 feet.

(6)

A North arrow.

(7)

Legal property boundaries, including:

The total project property boundary and size with distances marked to the nearest foot and bearings to the nearest degree.

Boundaries, size, and description of purpose of all existing easements and deed-restricted areas of the project property, with distances marked to the nearest foot and bearings to the nearest degree.

(8)

Existing natural resources and natural or man-made hydrologic features that are located within the site or receiving discharge from, or that may otherwise be impacted by, the proposed regulated activity, including but not limited to:

All existing natural resources, hydrologic features and drainage patterns including natural waterways, water bodies, wetlands, streams (intermittent and perennial), ponds, lakes, vernal pools, etc., natural infiltration areas and patterns, areas of significant natural evapotranspiration, and other water features and aquatic resources.

Any existing man-made drainage features, BMPs, conveyances, facilities, open channels, swales, drainage patterns, or other flood, stormwater, or drainage control features.

For the site, discharge points and locations of concentrated flows and their drainage areas.

For named waters, show names and their watershed boundaries within the site.

Special management areas (as per § 246-301Q).

(f)

For the water bodies, streams and wetlands identified in Subsection B(8)(a), label or otherwise show the following attributes, if applicable:

The designated use as determined by PADEP (25 Pa. Code Chapter 93);

Impairments listed on the PADEP "Integrated List" (as updated) and the listed source and cause of impairment;

[3]

Name, date, and target pollutant(s) for any approved total maximum daily load (TMDL); and

[4]

Drainages to water supply reservoirs.

(g)

Areas that are part of the Pennsylvania Natural Diversity Inventory (PNDI) and a list of potential impacts and clearances received (for regulated activities involving one acre or more proposed earth disturbance).

(h)

Woods, vegetated riparian buffers and other areas of natural vegetation.

(i)

Topography using contours (with elevations based on established benchmarks) at intervals of two feet. The datum used and the location, elevation and datum of any benchmarks used shall be shown.

(j)

Areas classified by the municipality as steep slopes.

(k)

Soil names and boundaries, general type of soils with hydrologic soil group noted, and in particular note areas most conducive to infiltration BMPs, such as Groups A and B, etc., estimated permeabilities in inches per hour, and location and other results of all soil tests and borings.

(l)

If present, areas with underlying carbonate geologic units, existing sinkholes, subsidence or other karst features, and any associated groundwater recharge areas with increased vulnerability to contamination.

(m)

Any contaminated surface or subsurface areas of the site.

(n)

Water supply wells.

Location of existing well(s) on the project property and delineation of the(ir) recharge area(s) (if known), or a fifty-foot diameter assumed recharge area;

Location of existing well(s) within 50 feet beyond the boundary of the project property boundary (if public water supply is proposed for the regulated activity).

(o)

Current FEMA 100-year floodplain boundaries, elevations, and floodway boundaries for any special flood hazard areas on or within 100 feet of the property.

(p)

Boundaries of a fifty-foot construction nondisturbance buffer to protect streams (intermittent and perennial), wetlands and other water bodies during construction of the proposed regulated activity.

(9)

Location of the proposed regulated activity, limits of earth disturbance (disturbed area), and BMPs and conveyances relative to the location of existing natural resources and hydrologic features and special management areas resulting from the site design process of § 246-304.

(10)

Description of existing and proposed ground cover and land use, including the type and total area.

(11)

Existing and proposed man-made features, including roads, paved areas, buildings, and other impervious and pervious surfaces on the project property (or an appropriate portion of the property as determined in consultation with the Municipal Engineer) and within the proposed disturbed area, and including the type and total area of the following:

Existing impervious surfaces (must differentiate existing impervious surfaces installed after March 27, 2013);

Existing impervious surfaces proposed to be replaced;

Existing impervious surfaces to be permanently removed and replaced with pervious ground cover;

New or additional impervious surfaces; and

Percent of the site covered by impervious surfaces for both the existing and proposed post-construction conditions.

(12)

The total extent of the upstream area draining through the site.

(13)

All BMPs, conveyances and other stormwater management facilities shall be located on the plan sheets, including design drawings, profile drawings, construction details, materials to be used, description of function, etc.

(14)

Complete delineation of the flow paths used for calculating the time of concentration for the predevelopment and post-construction conditions shall be included.

(15)

The locations of all existing and proposed utilities, sanitary sewers, on-lot wastewater facilities (including subsurface tanks and leach fields), and water supply lines within the site and within 50 feet beyond the proposed limits of earth disturbance.

(16)

A grading plan, including all areas of proposed earth disturbance and the proposed regulated activity and delineating the boundary or limits of earth disturbance of the site. The total disturbed area of the site shall be noted in square feet and acres.

(17)

Proposed final grade elevations and contours at intervals of two feet.

(18)

For each proposed BMP and conveyance included in the SWM site plan (including any to be located on any property other than the property being developed by the applicant), the following shall be included on the SWM site plan map or plan sheets:

Identification of the person responsible for ongoing inspections, operation, repair, and maintenance of the BMP or conveyance after completion of construction.

Delineation of the land area, structures, impervious surfaces, and conveyances draining to and from the BMP or conveyance.

Easements, as per the requirements of Article VII, that shall include:

Boundaries labeled with distances shown in feet and bearings to the nearest degree;

Notes or other documentation, as needed, to grant the municipality the right of access to all BMPs and conveyances for the purposes of inspection and enforcement of the requirements of this chapter, and any applicable O&M plans and O&M agreements;

[3]

Notes or other documentation, as needed, to grant the municipality the right of access to all roadways necessary to access all BMPs and conveyances, where roadways are not to be dedicated to the municipality;

[4]

Notes or other documentation as needed to grant the owner of any BMP or conveyance the right of access for the purpose of inspection, operation, maintenance, and repair of the BMP or conveyance that is to be owned, operated, and maintained by a person other than the municipality, and other than the owner of the property on which the BMP or conveyance is located;

[5]

A minimum twenty-foot-wide perimeter, or other width as determined by the municipality, around all BMPs and conveyances;

[6]

Sufficient vehicular ingress to and egress from a public right-of-way or roadway, as determined in consultation with the Municipal Engineer; and

[7]

Accompanying notes or other documentation as needed, and in accordance with Article VII, describing the type, purpose, and total area of easements, who the easement is granted to, and the rights, duties, and obligations of the parties with respect to every BMP or conveyance.

Boundaries of land areas (if any) for which deed restrictions are required for the purpose of protecting and prohibiting disturbance to a BMP or conveyance, indicating the area to which the restriction applies with distances shown in feet and bearings to the nearest degree, and a written description of the type, purpose, and nature of the restriction.

Other items that may be needed to comply with all other requirements of Article VII.

A written description of the following information shall be included in the SWM site plan:

Existing features, conditions, natural resources, hydrologic features, and special management areas [as listed in § 246-402B(8)];

How the site design achieves the requirements of § 246-304, and, if applicable, where they could not be achieved and why;

The overall stormwater management design concept for the project and how the site design achieves the requirements of §§ 246-301 through 246-311 of Article III;

Proposed features and conditions, proposed erosion and sediment control features, proposed BMPs, conveyances, and any other stormwater facilities;

A description of the effect of the project (in terms of flow alteration and runoff volumes, water quality and peak flows, etc.) on existing natural resources, hydrologic features and special management areas, adjacent and downgradient properties, and any existing municipal or other stormwater conveyance system(s), that may be affected by or receive runoff from the regulated activity (whether located within or outside of the area of the regulated activity), and specifics of how erosion, water quality and flow impacts will be avoided or otherwise mitigated;

(6)

Proposed nonpoint source pollution controls and justification and confirmation that the proposed project will not result in any increased pollutant loadings to any existing stream or stream impairment identified by PADEP, or to any receiving water body;

(7)

Expected project time schedule; and

(8)

Description of construction stages or project phases, if so proposed.

A detailed site evaluation conducted by a qualified licensed professional for projects proposed in areas of carbonate geology or karst topography and other environmentally sensitive areas, such as contaminated sites and brownfields, as described in § 246-301O and R of this chapter.

Stormwater runoff design computations and documentation, such as hydrologic, hydraulic, and structural computations, assumptions, BMP loading ratios, etc., consistent with the guidelines and criteria presented in the PA BMP Manual (as amended) or other guidance acceptable to the Municipal Engineer, and used in the design of the BMPs, conveyances and other features proposed to be utilized for stormwater management, or as otherwise necessary to demonstrate that the requirements of this chapter have been met, specifically including the requirements in §§ 246-301 and 246-304 through 246-309.

Inspections, operation and maintenance requirements. The following documents shall be prepared and submitted to the municipality for review and approval as part of the SWM site plan, in accordance with the requirements of Article VII, for each BMP and conveyance included in the SWM site plan (including any to be located on any property other than the property being developed by the applicant):

An O&M plan;

An O&M agreement;

Any easement agreements that are needed to ensure access, inspection, maintenance, operation, repair and permanent protection of any permanent BMP(s) and conveyances associated with the regulated activity;

Any written deed, deed amendment or equivalent document (if needed) to be recorded against a subject property, as shown on the SWM site plan maps or plan sheets, or recorded plan sheets for the purpose of protecting and prohibiting disturbance to a BMP or conveyance; and

Written approval, easement agreements, or other documentation for discharges to adjacent or downgradient properties when required to comply with § 246-301G and Article VII of this chapter.

An erosion and sediment control plan, where applicable, as prepared for and submitted to the Conservation District and/or municipality. A letter of adequacy from the Conservation District, if applicable, must be submitted to the municipality prior to (or as a condition of) the municipality's final approval of the SWM site plan.

A highway occupancy permit from the Pennsylvania Department of Transportation (PennDOT) District Office must be submitted to the municipality prior to (or as a condition of) the municipality's final approval of the SWM site plan when utilization of a PennDOT storm drainage system is proposed.

The SWM site plan shall be submitted to the municipality for review by the Municipal Engineer for consistency with this chapter and the respective PA Act 167 stormwater management plan(s). The Municipal Engineer will review the SWM site plan for any subdivision or land development for compliance with this chapter and the municipal SALDO provisions not otherwise superseded by this chapter.

If applicable, the applicant shall have received a letter of adequacy from the Conservation District or other PADEP approval for the proposed regulated activity prior to (or as a condition of) final approval by the municipality.

The Municipal Engineer will notify the applicant and the municipality in writing, within 45 calendar days, whether the SWM site plan is consistent with the requirements of this chapter. If the SWM site plan involves a subdivision and land development plan, the notification shall occur within the time period allowed by the MPC (as amended). If a longer notification period is provided by other statute, regulation, or ordinance, the applicant will be so notified by the municipality.

If the Municipal Engineer determines that the SWM site plan is consistent with this chapter, the Municipal Engineer shall forward a letter of consistency to the municipality, who shall then forward a copy to the applicant.

The municipality may approve the SWM site plan with conditions reasonably defined to make the SWM site plan compliant with the terms of this chapter, and, if so, shall provide the conditions for approval in writing.