Borough of Edgeworth, PA
Allegheny County
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Table of Contents
Table of Contents

§ 107-9 General requirements for stormwater management.

A. 
No regulated earth disturbance activities within the municipality shall commence until the requirements of this part are met.
B. 
Erosion and sediment control during regulated earth disturbance activities shall be addressed as required by § 107-11.
C. 
Postconstruction water quality protection shall be addressed as required by § 107-12. Operations and maintenance of permanent stormwater BMPs shall be addressed as required by Article IV.
D. 
All best management practices (BMPs) used to meet the requirements of this part shall conform to the state water quality requirements, and any more stringent requirements as determined by the municipality.
E. 
Techniques described in Appendix A (Low-Impact Development) of this part are encouraged, because they reduce the costs of complying with the requirements of this part and the state water quality requirements.
F. 
In conjunction with meeting the requirements of this part, the applicant shall refer to and meet all conditions and requirements set forth in the Borough of Edgeworth's Municipal Separate Storm Sewer System (MS4) Prohibited Discharge Ordinance.[1]
[1]
Editor's Note: See Part 2 of this chapter.
G. 
In conjunction with meeting the requirements of this part, the applicant shall refer to and meet all conditions and requirements set forth in the Borough of Edgeworth's total maximum daily load (TMDL) plan as adopted and revised.

§ 107-10 Permit requirements by other government entities.

The following permit requirements may apply to certain regulated earth disturbance activities, and must be met prior to commencement of regulated earth disturbance activities, as applicable:
A. 
All regulated earth disturbance activities subject to permit requirements by DEP under regulations at 25 Pa. Code Chapter 102.
B. 
Work within natural drainageways subject to permit by DEP under 25 Pa. Code Chapter 105.
C. 
Any stormwater management facility that would be located in or adjacent to surface waters of the commonwealth, including wetlands, subject to permit by DEP under 25 Pa. Code Chapter 105.
D. 
Any stormwater management facility that would be located on a state highway right-of-way, or require access from a state highway, shall be subject to approval by the Pennsylvania Department of Transportation (PENNDOT).
E. 
Culverts, bridges, storm sewers or any other facilities which must pass or convey flows from the tributary area and any facility which may constitute a dam subject to permit by DEP under 25 Pa. Code Chapter 105.

§ 107-11 Erosion and sediment control during regulated earth disturbance activities.

A. 
No regulated earth disturbance activities within the municipality shall commence until approval by the municipality of an erosion and sediment control plan for construction activities.
B. 
DEP has regulations that require an erosion and sediment control plan for any earth disturbance activity of 5,000 square feet or more, under 25 Pa. Code § 102.4(b).
C. 
In addition, under 25 Pa. Code Chapter 92,[1] a DEP "NPDES Construction Activities" permit is required for regulated earth disturbance activities.
[1]
Editor's Note: Chapter 92 of Title 25 of the Pennsylvania Code was reserved 10-8-2010, effective 10-9-2010. It was replaced by Chapter 92a, National Pollutant Discharge Elimination System (NPDES) Permitting, Monitoring and Compliance.
D. 
Evidence of any necessary permit(s) for regulated earth disturbance activities from the appropriate DEP regional office or County Conservation District must be provided to the municipality. The issuance of an NPDES Construction Permit [or permit coverage under the statewide General Permit (PAG-2)] satisfies the requirements Subsection A.
E. 
A copy of the erosion and sediment control plan and any required permit, as required by DEP regulations, shall be available at the project site at all times.

§ 107-12 Water quality requirements after regulated earth disturbance activities are complete.

A. 
No regulated earth disturbance activities within the municipality shall commence until approval by the municipality of a plan which demonstrates compliance with state water quality requirements after construction is complete.
B. 
The BMPs must be designed, implemented and maintained to meet state water quality requirements, and any other more stringent requirements as determined by the municipality.
C. 
To control postconstruction stormwater impacts from regulated earth disturbance activities, state water quality requirements can be met by BMPs, including site design, which provide for replication of preconstruction stormwater infiltration and runoff conditions, so that postconstruction stormwater discharges do not degrade the physical, chemical or biological characteristics of the receiving waters. As described in the DEP Comprehensive Stormwater Management Policy (No. 392-0300-002, September 28, 2002), this may be achieved by the following:
(1) 
Infiltration: replication of preconstruction stormwater infiltration conditions;
(2) 
Treatment: use of water quality treatment BMPs to ensure filtering out of the chemical and physical pollutants from the stormwater runoff; and
(3) 
Stream bank and streambed protection: management of volume and rate of postconstruction stormwater discharges to prevent physical degradation of receiving waters (e.g., from scouring).
D. 
DEP has regulations that require municipalities to ensure design, implementation and maintenance of best management practices ("BMPs") that control runoff from new development and redevelopment after regulated earth disturbance activities are complete. These requirements include the need to implement postconstruction stormwater BMPs with assurance of long-term operations and maintenance of those BMPs.
E. 
Evidence of any necessary permit(s) for regulated earth disturbance activities from the appropriate DEP regional office must be provided to the municipality. The issuance of an NPDES Construction Permit [or permit coverage under the statewide General Permit (PAG-2)] satisfies the requirements of Subsection A.
F. 
BMP operations and maintenance requirements are described in Article IV of this part.

§ 107-13 Stormwater detention facilities.

The following provisions shall be considered the overriding performance standards against which all proposed stormwater control measures shall be evaluated, and they shall apply to all areas of the Borough.
A. 
Stormwater shall not be permitted, as a result of development undertaken after adoption of this part, to collect upon any property, or to pass from one property to another in a concentrated flow without benefit of a legal easement, or to cross a public street on the surface.
B. 
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:
(1) 
To assure that the maximum rate of stormwater runoff is no greater after development than that prior to development activities; and
(2) 
To manage the quality, velocity and direction of resulting stormwater runoff in a manner which will not adversely impact the health on, or value of, any affected properties.
C. 
In the case of a development in which the total of the building and paved surfaces on the site exceed 5,000 square feet, the developer shall provide as part of the design a stormwater management narrative signed and sealed by an engineer licensed in the Commonwealth of Pennsylvania. The stormwater management narrative shall include an analysis of both pre- and postdeveloped runoff conditions.
(1) 
For the analysis of redevelopment projects 20% of the existing impervious surface shall be considered meadow in good condition.
(2) 
Postdevelopment runoff rates after development shall not exceed the predeveloped runoff rates including the reduction in impervious surface required for redevelopment projects.
D. 
Design storms:
(1) 
The one-, two-, five-, ten-, twenty-five-, fifty- and one-hundred-year design storm frequencies shall be used for analyzing stormwater runoff in pre- and postdeveloped conditions as well as for the designing runoff control facilities.
(2) 
The SCS, Type II Rainfall Distribution shall be used for all analysis. The design storms, along with the twenty-four-hour total rainfall for these storm frequencies for the watershed area:
Design Storm
Rainfall Depth 24 Hours
(inches)
1 year
1.97
2 year
2.60
5 year
3.30
10 year
3.90
25 year
4.40
50 year
4.80
100 year
5.20
E. 
Release rate:
(1) 
The postdeveloped runoff rate may not exceed 90% of the predeveloped runoff rate for the one-, two-, five-, ten-, twenty-five-, fifty-, and one-hundred-year design storm frequencies.
F. 
Method of computation:
(1) 
All computations used in conjunction with the analysis and design of stormwater management facilities shall be based on one or more of the following methods:
(a) 
HEC-HMS: U. S. Army Corps of Engineers Hydrologic Modeling System.
(b) 
TR-55: Soil Conservation Service Technical Release No. 55.
(c) 
TR-20: Soil Conservation Service Technical Release No. 20.
(d) 
Modified Rational Method (watersheds less than 20 acres).
(e) 
Penn State Runoff Model.
(2) 
These methods for determining peak discharge shall be used 1) to determine predevelopment runoff conditions; 2) to analyze the impact of development; and 3) to perform calculations in the design of any detention/retention facilities used in controlling runoff. These methods of runoff computation developed and used by the Soil Conservation Service[1] and other authorities are hereby adopted by the Borough.
[1]
Editor's Note: The former Soil Conservation Service is now known as the Natural Resources Conservation Service.
G. 
Criteria for stormwater detention/retention facilities.
(1) 
If detention/retention facilities are utilized for the development site, the facility(s) shall be designed such that the postdevelopment peak runoff rates from the developed site are controlled to those rates previously defined for the one-, two-, five-, ten-, twenty-five-, fifty-, and one-hundred-year predeveloped design storms. Stormwater detention facilities shall drain within 24 hours to 72 hours from the end of the storm event.
(2) 
All detention/retention facilities shall be equipped with multistage outlet structure to provide discharge controls or the one-, two-, five-, ten-, twenty-five-, fifty-, and one-hundred-year storm frequencies provisions shall also be made for safely passing the postdevelopment one-hundred-year storm runoff flows without damaging (i.e., impairing the continued function of) the facilities.
(3) 
Where detention facilities will be utilized, multiple-use facilities, such as lakes, ball fields or similar recreational uses, are encouraged wherever feasible.
(4) 
Other considerations which should be incorporated into the design of the detention facilities include:
(a) 
Inflow and outflow structures shall be designed and installed to prevent erosion, and bottoms of impoundment-type structures should be protected from soil erosion.
(b) 
Control and removal of debris both in the storage structure and in all inlet or outlet devices shall be a design consideration.
(c) 
Inflow and outflow structures, pumping stations, and other structures shall be protected and designed to minimize safety hazards.
(d) 
The water depth of a storage pond which is not fenced shall be limited to two feet unless approved by the Borough Engineer. Otherwise, appropriate landscaped fencing at least four feet in height shall be required.
(e) 
Landscaping shall be provided for the facility which harmonizes with the surrounding area.
(f) 
All stormwater detention facilities shall be screened from view of existing roads or streets located within the Borough, which is a minimum of six feet in height with sufficient access for maintenance vehicles. The screening material must be approved by the Borough. Landscaping of the pond embankment shall not be permitted at any time.
(g) 
The facility shall be located to facilitate maintenance, considering the frequency and type of equipment that will be required.
(h) 
The facility shall be equipped with an access road at least eight feet wide and with a maximum of grade of 15%.
(i) 
All pond outlet structures shall have suitable gaskets to prevent leakage and piping of water through the pond embankment. All storm pipe installed through the pond embankment must be constructed of reinforced concrete pipe.
(j) 
The emergency spillway shall be sized to convey the one-hundred-year peak flow rate with a minimum of one foot of free board. All emergency spillways shall include a cutoff wall.
(5) 
A geotechnical investigation report for the construction of the stormwater detention/retention and infiltration facilities must be provided including design recommendations for embankment construction, interior and exterior slopes, drainage swales and infiltration areas.

§ 107-14 Collection and conveyance systems.

A. 
Applicants are encouraged to design conveyance systems that encourage infiltration and improve water quality wherever practicable.
B. 
Wherever conveyance channels are necessary, drainage shall be maintained by an open channel with landscape banks designed to carry the one-hundred-year, twenty-four-hour stormwater runoff from upstream contributory areas. If the runoff from stormwater collection and conveyance facilities would drain over land to a stormwater detention facility, the twenty-five-year frequency storm event may be used. The Borough Engineer with the approval of the Borough may increase the design storm, as conditions require. All open channels shall be designed with one foot of freeboard above the design water surface elevation of the design runoff condition.
C. 
Flood relief channels shall be provided and designed to convey the runoff from the one-hundred-year, twenty-four-hour storm, such that a positive discharge of this runoff is to a natural drainagecourse with a defined bed and bank.
D. 
Manholes and/or inlets shall not be spaced more than 300 feet apart for pipe sizes up to 24 inches in diameter and not more than 450 feet apart for larger pipe sizes.
E. 
Where drainage swales are used in lieu of or in addition to storm sewers, they shall be designed to carry the required runoff without erosion and in a manner not detrimental to the properties they cross. Drainage swales shall provide a minimum grade of 1% but shall not exceed a grade of 9%. Drainage swales used strictly for conveyance are not the same as open vegetated channels.
F. 
Street curbing for the purpose of stormwater conveyance is discouraged. On streets that must contain curbing, storm sewers shall be placed in front of the curbing. To the greatest extent possible, storm sewers shall not be placed directly under curbing. At curbed street intersections, storm inlets shall be placed in the tangent section of the road.
G. 
Use of grassed swales or open vegetated swales in lieu of curbing to convey, infiltrate and/or treat stormwater runoff from roadways is encouraged. Inlets shall be placed at the center of the shoulder swale draining the street and shall be located no closer than four feet from the edge of the cartway.
H. 
When requested by the Borough the developers shall obtain or grant a minimum twenty-foot-wide drainage easement over all storm sewers, drainage swales, channels, etc., that are a component of the stormwater management system when located within undedicated land. All permanent detention basins and/or other stormwater management facilities providing stormwater control for other than a single residential lot shall be located within a defined drainage easement that allows proper legal access and maintenance vehicle access.
I. 
No property owner shall obstruct or alter the flow, location or carrying capacity of a stream, channel or drainage swale to the detriment of any other property owner, whether upstream or downstream. All subdivision and/or land development plans containing streams, channels, drainage swales, storm sewers or other conveyance systems that cross property boundaries, existing or proposed, or whose discharge crosses such boundaries shall contain a note stating the above.
J. 
Water quality inlets. Storm drainage systems that collect runoff from parking areas and/or loading areas exceeding 10,000 square feet of impervious coverage and discharge to stormwater management systems, including surface or subsurface infiltration systems, shall have a minimum of one water quality inlet per each acre of drainage area. The purpose of water quality inlets is to remove oil, grease, and heavy particulates or total suspended solids, hydrocarbons and other floating substances from stormwater runoff. Methods other than water quality inlets may be permitted if the applicant demonstrates to the Borough's satisfaction that any such alternative will be as effective and as easily maintained. Periodic cleaning of these systems shall be addressed in the operation and maintenance plan submitted to the Borough.
K. 
Suitable drainage structures, culverts, storm sewers, swales and related installations shall be provided along roads to ensure removal of stormwater from all gutters, at all low points and at intervals elsewhere not exceeding 600 feet, such that the width of stormwater flow in any gutter does not exceed 1/4 of the total cartway width.
L. 
No stormwater pipe (public or private) shall be less than 15 inches in diameter that conveys surface runoff. All stormwater pipes shall be concrete unless otherwise approved by the Borough. The minimum pipe slope shall be such that a minimum of two feet per second velocity is maintained. Where a culvert or pipe is used to replace a stream, the cross-sectional area shall be at least as large as the original stream channel. All stormwater BMPs shall be constructed in accordance with the Borough's "Standard Details." Minimum pipe cover shall conform to the manufacturer's recommendations. Stormwater conveyance pipes utilized in BMPs shall have a pipe size of four-inch diameter or larger.
M. 
Where open watercourses for stormwater drainage are used the following standards shall apply:
(1) 
Artificial channels shall be of trapezoidal cross section, with the channel width at the bottom at least 10 times the maximum water depth which would be produced by the one-hundred-year design storm and with rough, permeable and flexible sides and bottom. No artificial channel shall be used to replace a natural stream.
(2) 
At all points in the drainage system the velocity shall be less than the erosion threshold of the conveyance material, including at the outlet from the construction area or subdivision site.
N. 
All stormwater collection and conveyance facilities (pipes, swales, and structures) shall be designed for a one-hundred-year design storm event, unless the runoff would naturally drain overland to a stormwater detention facility, in which case a twenty-five-year design storm event may be used. All drainage facilities shall be designed to contain the energy grade line for the peak flow rate for the design storm within the structures a minimum of two feet below surface elevation. The hydraulic grade line must be within the pipe. Swales and channels shall provide at least one foot of freeboard above the energy grade line. Backwater effects of pipes discharging under surcharge conditions shall be included in the calculations.
O. 
All workmanship and materials shall conform to the Borough's construction standards. In addition, all workmanship and materials shall conform to the latest edition of PennDOT Form 408 and be supplied by manufacturers or suppliers listed in PennDOT's Bulletin 15.
P. 
All connections to existing storm sewer pipes shall be made by construction of a suitable junction box (inlet or manhole) to provide access for cleanout. No blind connections shall be permitted.
Q. 
All pipe outlets shall discharge onto a stone riprap blanket to prevent erosion of soil. Riprap shall be sized considering pipe exit velocities.
R. 
The discharge of stormwater runoff shall be to a well-defined drainagecourse, which has a defined bed and bank. If stormwater runoff cannot be discharged to a defined drainagecourse, documentation of written permission from each downstream property owner shall be provided for all properties between the source of discharge and the defined drainagecourse.
S. 
Manholes for pipe sizes of 24 inches or less shall be spaced at a maximum of 400 feet and, for larger pipes sizes, the maximum distances between manholes shall be 600 feet. In addition, manholes shall be installed at all points of changes in horizontal alignment and vertical grade. Inlets may be substituted for manholes where practical.
T. 
Inlets at street intersections shall be placed on the tangent and not on the curved portion of the intersection radii.
U. 
Manhole and inlet structures and castings shall conform to the Pennsylvania Department of Transportation Form 408 and PennDOT Standards for Roadway Construction. Inlet grates shall be bicycle safe. Frames and grates shall be cast iron or structural steel. Concrete frames shall not be permitted.
V. 
All roof drains shall discharge to an on-lot sump, or to a storm sewer system which is controlled by a detention pond. Outlets from roof drain sumps shall not discharge directly to fill slopes. Outlets shall not discharge directly to the gutter line of any street. All pipes from roof drains shall be a minimum four-inch Schedule 40 ABS, PVC or SDR 26 pipe. Four-inch Schedule 40 PVC or ABS pipe is required for a distance of 10 feet from the foundation of the dwelling. No stormwater drainage system shall be permitted to be constructed through any curbing on any public street. Minimum pipe size for sump stormwater piping is four inches.
W. 
All bridges and culverts shall be designed to support expected loads and to carry expected flows and shall be designed to meet current standards of the Pennsylvania Department of Transportation. All bridges and culverts shall be subject to all permits required by the Pennsylvania Department of Environmental Protection, Bureau of Dams and Waterways.