City of Greensburg
The City of Greensburg adopted stormwater management regulations to manage and control stormwater runoff resulting from alteration and disturbance activities related to development. In accordance with the watershed stormwater management plans adopted pursuant to the Pennsylvania Stormwater Management Act, the city seeks to utilize the desirable existing natural drainage systems and to preserve the flood-carrying capacity of the streams. While the City of Greensburg looks to use these regulations to encourage natural infiltration of rainfall to enhance groundwater supplies and stream flows, the ordinance provides for adequate maintenance of all permanent stormwater structures in the municipality.
Excerpts from the City of Greensburg Stormwater Code
Chapter 219. SEWERS AND SEWAGE DISPOSAL
Article V. Stormwater Management
City of Greensburg, PA
§ 219-107. Stormwater management performance standards.
A. Stormwater management performance districts.
- For purposes of stormwater management, the City of Greensburg is divided into the following stormwater management districts:
- Northjmont Watershed.
- Shaller's Watershed.
- The location and boundaries of the watersheds and subareas are shown on the Municipal Stormwater Management District Map hereby adopted as part of this section.
B. General standards. The following provisions shall be considered the overriding performance standards against which all proposed stormwater control measures shall be evaluated and shall apply throughout the City of Greensburg:
- Any landowner and any person engaged in the alteration or development of land which may affect stormwater runoff characteristics shall implement such measures as are reasonably necessary to prevent injury to health, safety or other property. Such measures shall include such actions as are required:
- To assure that the maximum rate of stormwater runoff is no greater after development than prior to development activities; or
- To manage the quantity, velocity and direction of resulting stormwater runoff in a manner which otherwise adequately protects health and property from possible injury.
- The stormwater management plan for the development site must consider all stormwater runoff flowing over the site.
- No discharge of toxic materials (i.e., materials that would be in violation of the Pennsylvania Clean Streams Law) shall be permitted into any stormwater management system.
C. Watershed standards.
- Storm frequencies. Stormwater management facilities on all development sites shall control the peak stormwater discharge for the two-, ten- , twenty-five- and one-hundred-year storm frequencies. The SCS twenty-four-hour, Type II rainfall distribution shall be used for analyzing stormwater runoff for both pre- and post-development conditions.
- Calculation methods.
- Development sites. For purpose of computing peak flow rates and runoff hydrographs from development sites, calculations shall be performed using one (1) of the following: SCS publications, Technical Release (TR) 55 or 20, HEC Ior Penn State Runoff Model. For sites less than five (s) acres, the Rational Method may be used as approved by the municipal/consulting engineer. The intensity for the rational formula will be the rainfall depths listed above.
- Stormwater collection/conveyance facilities. For the purposes of designing storm sewers, open swales and other stormwater runoff collection and conveyance facilities, any of the above-listed calculation methods or the Rational Method may be used. Rainfall intensities for design should be obtained from the Pennsylvania Department of Transportation rainfall charts.
- Predevelopment conditions. Predevelopment conditions shall be assumed to be those which exist on any site. Hydrologic conditions for all areas with pervious cover (i.e., field’s woods, lawn areas, pastures, cropland, etc.) shall be assumed to be in °good0 condition, and the lowest recommended SCS runoff curve number (CN) shall be applied for all pervious land uses within the respective range for each land use and hydrologic soil group.
- Routing of hydrographs through the detention/retention facilities for the purpose of designing those facilities shall be accomplished using the Modified-Puls Method or recognized reservoir routing method subject to the approval of the municipality and county.
- Release rate percentage.
- Definition. The release rate percentage defines the percentage of the predevelopment peak rate of runoff that can be discharged from an outfall on the site after development or alterations within the subarea. A delineation of the release rate percentages by subarea is shown on the Municipal Stormwater Management District Map.C2l
- Procedure for use.
- Identify the specific subarea in which the development site is located and obtain the subarea release rate percentage from the watershed map.
- Compute the pre- and post-development runoff hydrographs for each stormwater outfall on the development site using an acceptable calculation method for the two-, ten- , and twenty-five- and one-hundred-year storms. Apply to on-site detention for stormwater management but include any techniques to minimize impervious surfaces and/or increase the time of concentration for stormwater flowing from the development site. If the post-development peak runoff rate and volume are less than or equal to the pre-development peak runoff rate and volume, then additional stormwater control shall not be required at that outfall. If the post-development peak runoff rate and volume are greater than the pre-development peak runoff rate and volume, then stormwater detention will be required and the capacity of the detention facility must be calculated in the manner prescribed below.
- Multiply the subarea release rate percentage by the pre-development rate of runoff from the development site to determine the maximum allowable release rate from any detention facility for the four (4) prescribe storm events.
- Design the outlet control facility and size the volume of the detention facility using the calculated post development hydrograph and accepted hydrograph routing procedures in consideration of the maximum allowable release rate.
§ 219-110. Maintenance of stormwater management controls.
A. Maintenance responsibilities.
- The stormwater management plan for the development site shall contain an operation and maintenance plan prepared by the developer and approved by the Municipal/Consulting Engineer. The operation and maintenance plan shall outline required routine maintenance actions and schedules necessary to ensure proper operation of the facility (ies).
- The stormwater management plan for the development site shall establish responsibilities for the continuing operation and maintenance of all proposed stormwater control facilities, consistent with the following principles:
- If a development consists of structure or lots which are to be separately owned and in which streets, sewers and other public improvements are to be dedicated to the municipality, stormwater control facilities shall also be dedicated to and maintained by the municipality. All stormwater control facilities must be on a separate parcel(s) dedicated by deed to the municipality. Dedication and acceptance therefor shall be at the sole election of the municipality.
- If a development site is to be maintained in a single ownership or if sewers and other public improvements are to be privately owned and maintained, then the ownership and maintenance of stormwater control facilities shall be the responsibility of the owner or private management entity.
- The Council of the City of Greensburg, with recommendations from the Municipal/Consulting Engineer, shall make the final determination on the continuing maintenance responsibilities prior to final approval of the stormwater management plan. The Council reserves the right to accept the ownership and operating responsibility for any or all of the stormwater management controls.
B. Maintenance agreement for privately owned stormwater facilities.
- Prior to final approval of the site's stormwater management plan, the property owner shall sign and record, in the Westmoreland County Recorder of Deeds office, a maintenance agreement covering all stormwater control facilities which are to be privately owned. The agreement shall stipulate that:
- The owner shall operate and maintain all facilities in accordance with the approved operation and maintenance schedule and shall keep all facilities in a safe and attractive manner.
- The owner shall convey to the municipality easements and/or rights-of-way to assure access for periodic inspections by the municipality and maintenance if required.
- The owner shall keep on file with the municipality the name, address and telephone number of the person or company responsible for maintenance activities; in the event of change, now information will be submitted to the municipality within ten (10) days of the change.
- If the owner fails to maintain the stormwater control facilities, the municipality is hereby authorized and directed to give notice, by personal service or by United States Mail to the owner by certified mail, to correct the problem(s) or to otherwise conform to the requirements of the operations and maintenance plan within thirty (30) days after issuance of such notice.
- In case the owner shall neglect, fail or refuse to comply with such notice within the period of time stated therein, the municipality may perform the necessary maintenance work or corrective action and the owner shall reimburse the municipality for all cost, including reasonable attorney's fees, together with any additional payment authorized by law, and may be collected by the municipality from such owner in the manner provided by law for the collection of municipal claims or by an action of assumption and the said sum shall be a legal and/or equitable lien or charge upon the subject land and facilities from the date of completion of said work.
- Other items may be included in the agreement where determined necessary to guarantee the satisfactory maintenance of all facilities. The maintenance agreement shall be subject to the review and approval of the municipal solicitor and Council.
§ 219-111. Stormwater plan requirements.
A. General requirements. No final subdivision/land development plan shall be approved, no permit authorizing construction issued nor any earthmoving or land disturbance activity initiated until the final stormwater management plan for the development site is approved in accordance with the provisions of this article.
B. Exemptions for small developments.
- At the time of application, the municipality shall determine if the subdivision/land development qualifies as a small development and, therefore, is eligible for a simplified stormwater management plan submission. For the purpose of this article, a small development is any subdivision or land development which results (or will result when fully constructed) in the creation of five thousand (5,000) or less square feet of impervious area and one (1) area or less of any land cover change.
- Applications for small developments shall include a plan which describes the type and location of proposed on-site stormwater management techniques or the proposed connection to an existing storm sewer system. The plan should show accurately site boundaries, two-foot-interval contours, locations of watershed and/or subarea boundaries on the site (if applicable) and any watercourses, floodplains or existing drainage facilities or structures located on the site. Contingent upon the approval of the Municipal/Consulting Engineer, alternative runoff computational techniques such as the Rational Method may be used where applicable. The municipality reserves the right to require that the plan be prepared by a registered professional engineer, surveyor or landscape architect.
- The Municipal/Consulting Engineer shall review and approve the proposed provisions for stormwater management in accordance with the standards and requirements of this article.
C. Stormwater plan contents.
- General format. The stormwater plan shall be drawn to a scale of not less than one (1) inch equals two hundred (200) feet. All sheets shall contain a title block with the name and address of the applicant and engineer, scale, North arrow, legend and date of preparation.
- Existing and proposed features. The plan shall show the following:
- Watershed location: provide a key map showing the location of the development site within the watershed(s) and watershed subarea(s). On all site drawings, show the boundaries of the watershed(s) and subarea(s) as they are located on the development site and identify watershed name(s) and subarea number(s).
- Floodplain boundaries: identify one-hundred-year floodplains on the development site (as appropriate) based on the municipal Flood Insurance Study maps.
- Natural features: show all bodies of water (natural or artificial), watercourses (permanent and intermittent), swales, wetlands and other natural drainage courses in the development site or which will be affected by runoff from the development.
- Soils: provide an overlay showing all soil types and boundaries within the development site (consult Westmoreland County Soil Survey).
- Contours: show existing and final contours at intervals of two (2) feet; in areas with slopes greater than twenty percent (20%), ten-foot contour intervals may be used.
- Land cover: show existing and final land cover classifications as necessary to support and illustrate the runoff calculations performed.
- Drainage area delineations: show the boundaries of the drainage areas employed in the runoff calculations performed.
- Stormwater management controls: show any existing stormwater management or drainage controls and/or structures, such as sanitary and storm sewers, swales, culverts, etc., which are located on the development site or which are located off-site but will be affected by runoff from the development.
- Professional certification. The stormwater management plan (including all calculations) must be prepared and sealed by a registered professional engineer, surveyor or landscape architect with training and expertise in hydrology and hydraulics. Documentation of qualifications may be required by the municipality.
- Runoff calculations. Calculations for determining pre- and post-development discharge rate and for designing proposed stormwater control facilities must be submitted with the stormwater management plan. All calculations shall be prepared using the methods and data prescribed by §219-107 of this article.
- Stormwater controls. All proposed stormwater runoff control measures must be shown on the plan, including methods for collecting, conveying and storing stormwater runoff on-site, which are to be used both during and after construction. Erosion and sedimentation controls shall be shown in accordance with applicable municipal and county conservation district requirements. The plan shall provide information on the exact type, location, sizing, design and construction of all proposed facilities and the relationship to the existing watershed drainage system.
- If the development is to be constructed in stages, the applicant must demonstrate that stormwater facilities will be installed to manage stormwater run-off safely during each stage of development.
- A schedule for the installation of all temporary and permanent stormwater control measures and devices shall be submitted.
- If appropriate, a justification shall be submitted as to why any preferred stormwater management techniques, as listed in §219-108 of this article, are not proposed for use.
- Easements, rights-of-way and deed restrictions. All existing and proposed easements and rights-of-way for drainage and/or access to stormwater control facilities shall be shown and the proposed owner identified. Show any areas subject to special deed restrictions relative to or affecting stormwater management on the development site.
- Other permits/approvals. A list of any approvals/permits relative to stormwater management that will be required from other governmental agencies (including DER Chapter 105 and 106 permits) and anticipated dates of submission/receipt should be included with the stormwater plan submission. Copies of permit applications may be requested by the municipality where they may be helpful for the plan review.
- Maintenance program. The application shall contain a proposed maintenance plan for all stormwater control facilities in accordance with the following:
- Identify the proposed ownership entity (e.g. Municipality, property owner, Private Corporation, homeowners association or other entity).
- Include a maintenance program for all facilities, outlining the type of maintenance activities, probable frequencies, personnel and equipment requirements and estimated annual maintenance costs.
- Identify method of financing continuing operation and maintenance if the facility is to be owned by other than the municipality.
- Submit any legal agreements required to implement the maintenance program and copies of the maintenance agreement as required by this article.
- Financial guaranties. The developer shall post securities with the City of Greensburg to secure the completion of all required improvements in accordance with the provisions of this article, and the amount and administration shall be in accordance with Section 509 of the Pennsylvania Municipalities Planning Code.
§ 219-115. Inspection of stormwater management controls.
A. The Municipal/Consulting Engineer or a designated representative shall inspect the construction of the temporary and permanent stormwater management system for the development site. The permittee shall notify the engineer forty-eight (48) hours in advance of start and completion of key development phases such as:
- Preliminary site preparation, including stripping of vegetation, stockpiling of topsoil and construction of temporary stormwater management and erosion control facilities.
- Rough grading. Permanent drainage construction and other site improvements and any permanent ground cover.
- Construction of all permanent stormwater control facilities. (4) Final grading and site stabilization.
B. No work shall commence on any subsequent phase until the preceding one has been inspected and approved. If there are deficiencies in any phase, the Municipal/Consulting Engineer shall issue a written description of the required corrections and stipulate the time by which they must be made.
C. If, during construction, the contractor or permitted identifies any site condition, such as subsurface soil conditions or alterations in surface or subsurface drainage, which could affect the feasibility of the approved stormwater facilities, he/she shall notify the Municipal/Consulting Engineer within twenty-four (24) hours of the discovery of such conditions and request a field inspection. The Municipal/Consulting Engineer shall determine if the condition requires a stormwater plan modification.
D. In cases where stormwater facilities are to be installed in areas of landslide-prone soils or other special site conditions exist, the municipality may require special precautions such as soil testing and core borings, full-time inspectors and/or similar measures. All cost of any such measures shall be borne by the permitted.
Greensburg Ordinance Stormwater Code
Greensburg Stormwater Management Plan