Questions about eCode360? Municipal users Join us daily between 12pm and 1pm EDT to get answers and other tips!
Borough of Elizabethtown, PA
Lancaster County
By using eCode360 you agree to be legally bound by the Terms of Use. If you do not agree to the Terms of Use, please do not use eCode360.
Table of Contents
Table of Contents
[Ord. 954, 12/19/2013]
1. 
Preparation of an SWM site plan is required for all regulated activities, unless preparation and submission of the SWM site plan is specifically exempted according to § 401 or the activity qualifies as a small project.
2. 
No regulated activities shall commence until the Borough of Elizabethtown issues unconditional written approval of a land disturbance plan in the form of a stormwater permit.
3. 
SWM site plans approved by the Borough of Elizabethtown, in accordance with § 406, shall be on site throughout the duration of the regulated activity.
4. 
The Borough may, after consultation with the DEP, approve measures for meeting the state water quality requirements other than those in this chapter, provided that they meet the minimum requirements of, and do not conflict with, state law, including, but not limited to, the Clean Streams Law. The Borough shall maintain a record of consultations with the DEP pursuant to this subsection. Where an NPDES permit for stormwater discharges associated with construction activities is required, issuance of an NPDES permit shall constitute satisfaction of consultation with the DEP. The applicant shall initiate and facilitate all consultations between the DEP and the Borough.
5. 
For all regulated activities, erosion and sediment control and stormwater management BMPs shall be designed, implemented, operated and maintained to meet the purposes and requirements of this chapter and to meet all requirements under Title 25 of the Pennsylvania Code and the Clean Streams Law. Various BMPs and their design standards are listed in the E&S Manual, BMP Manual and § 307 of this chapter.
6. 
Developers have the option to propose a regional stormwater management plan or participate in a regional stormwater management plan developed by others. A regional stormwater management plan may include off-site volume and rate control, as appropriate, and supported by a detailed design approved by the Borough in accordance with § 301, Subsection 4. A regional stormwater management plan must meet all of the volume and rate control standards required by this chapter for the area defined by the regional stormwater management plan, but not necessarily for each individual development site. Appropriate agreements must be established to ensure the requirements of this chapter and the requirements of the regional stormwater management plan are met.
7. 
Unless prohibited by Chapter 27, Zoning, or Chapter 8, Floodplains, which regulates construction and development within the areas of the Borough subject to flooding, and any other applicable requirements of the Flood Plain Management Act,[1] stormwater management facilities located in the floodplain are permitted when designed and constructed in accordance with the provisions of the BMP Manual, regulatory requirements and the requirements of this chapter.
[1]
Editor's Note: See 32 P.S. § 679.101 et seq.
8. 
Impervious Areas.
A. 
The measurement of impervious area shall include all of the impervious areas in the total proposed development even if development is to take place in stages or phases.
B. 
For development taking place in stages or phases, the entire development plan must be used in determining conformance with this chapter.
C. 
Any areas designed to initially be gravel or crushed stone shall be assumed to be impervious if subject to vehicular/pedestrian traffic.
9. 
All regulated activities shall include such measures as necessary to:
A. 
Protect health, safety and property;
B. 
Meet the water quality goals of this chapter by implementing measures to:
(1) 
Protect and/or improve the function of floodplains, wetlands and wooded areas.
(2) 
Protect and/or improve native plant communities, including those within the riparian corridor.
(3) 
Protect and/or improve natural drainageways from erosion.
(4) 
Minimize thermal impacts to waters of this commonwealth.
(5) 
Disconnect impervious surfaces by directing runoff to pervious areas, wherever possible.
10. 
The design of all stormwater management facilities over karst shall include an evaluation of measures to minimize adverse effects and to certify the following:
A. 
No stormwater facilities shall be placed in, over or immediately adjacent to the following features:
(1) 
Sinkholes.
(2) 
Closed depressions.
(3) 
Lineaments in carbonate areas.
(4) 
Fracture traces.
(5) 
Caverns.
(6) 
Intermittent lakes.
(7) 
Ephemeral streams.
(8) 
Bedrock pinnacles (surface or subsurface).
B. 
Stormwater management facilities shall not be located closer than 100 feet from the rim of sinkholes or closed depressions, nor within 100 feet from disappearing streams; nor shall these facilities be located closer than 50 feet from lineaments or fracture traces; nor shall these facilities be located closer than 25 feet from surface or identified subsurface pinnacles unless lined with an impermeable liner or equivalent design as signed and sealed by a professional geologist.
C. 
Stormwater resulting from regulated activities shall not be discharged into sinkholes.
D. 
It shall be the developer's responsibility to verify if the development is underlain by carbonate geology. The following certificate shall be included on all stormwater site plans and shall be signed and sealed by the developer's professional geologist:
"I, ___________________, certify that the proposed stormwater/BMP facility (circle one) is/is not underlain by carbonate geology."
E. 
Whenever an SWM facility will be located in an area underlain by carbonate geology, a geological evaluation of the proposed location by a registered professional geologist shall be conducted to determine susceptibility to sinkhole formation. The evaluation may include the use of impermeable liners to reduce or eliminate the separation distances listed in Subsection 10A and B.
11. 
Infiltration BMPs shall be spread out, made as shallow as practicable, and located to maximize use of natural on-site infiltration features while still meeting the other requirements of this chapter. Infiltration BMPs shall include pretreatment BMPs unless shown to be unnecessary.
12. 
Infiltration BMPs intended to receive runoff from developed areas shall be selected based on suitability of soils and development site conditions and shall be constructed on soils that have the following characteristics:
A. 
A minimum depth of 24 inches between the bottom of the facility and the limiting zone. Modifications will be considered if it is demonstrated to the satisfaction of the Borough that the selected BMP has design criteria which allow for a smaller separation.
B. 
A stabilized infiltration rate sufficient to accept the additional stormwater load and drain completely as determined by field tests conducted by the applicant's professional designer.
(1) 
The stabilized infiltration rate is to be determined in the same location and within the same soil horizon as the bottom of the infiltration facility.
(2) 
The stabilized infiltration rate is to be determined as specified in the BMP Manual.
13. 
The calculation methodology to be used in the analysis of volume and peak rates of discharge shall be as required in § 305.
14. 
A planting plan is required for all vegetated stormwater BMPs.
A. 
Native or naturalized/noninvasive vegetation suitable to the soil and hydrologic conditions of the development site shall be used unless otherwise specified in the BMP Manual.
B. 
Invasive vegetation may not be included in any planting schedule. The List of Invasive Vegetation in Pennsylvania can be found on the DCNR website at the following address: www.dcnr.state.pa.us/forestry/plants/invasiveplants/index.htm.
C. 
The limit of existing, native vegetation to remain shall be delineated on the plan along with proposed construction protection measures.
D. 
Prior to construction, a tree protection zone shall be delineated at the dripline of the tree canopy. All trees scheduled to remain during construction shall be marked; however, where groups of trees exist, only the tress on the outside edge need to be effectively marked to promote protection of the trees during construction. No construction, storage of material, temporary parking, pollution of soil, or regrading shall occur within the tree protection zone.
E. 
All planting shall be performed in conformance with good nursery and landscape practice. Plant materials shall conform to the standards recommended by the American Association of Nurseryman, Inc., in the American Standard of Nursery Stock.
(1) 
Planting designs are encouraged to share planting space for optimal root growth whenever possible.
(2) 
No staking or wiring of trees shall be allowed without a maintenance note for the stake and/or wire removal within one year of planting.
15. 
Areas proposed for infiltration BMPs shall be protected from sedimentation and compaction during the construction phase to maintain maximum infiltration capacity, including but not limited to fencing to limit construction traffic over the infiltration area. Staging of earthmoving activities and selection of construction equipment should consider this protection.
16. 
Infiltration BMPs shall not be constructed nor receive runoff from disturbed areas until the entire contributory drainage area to the infiltration BMP has achieved final stabilization.
17. 
A minimum twenty-foot-wide access easement shall be provided for all SWM facilities with tributary areas equal to or greater than 1,000 square feet and not located within a public right-of-way. Easements shall provide for ingress and egress to a public right-of-way. This shall be noted on the plan.
18. 
Drainage easements shall be provided where the conveyance, treatment or storage of stormwater, either existing or proposed, is identified on the SWM site plan. Drainage easements shall be provided to contain and convey the one-hundred-year frequency flood.
19. 
The Borough may require additional stormwater control measures for stormwater discharges to special management areas, including, but not limited to:
A. 
Water bodies listed as "impaired" on Pennsylvania's Clean Water Act 303(d)/305(b) Integrated List.
B. 
Any water body or watershed with an approved total maximum daily load (TMDL).
C. 
Critical areas with sensitive resources (e.g., state-designated special protection waters, cold-water fisheries, carbonate or other groundwater recharge areas highly vulnerable to contamination, drainage areas to water supply reservoirs, source water protection zones, etc.).
20. 
Roof drains and sump pumps shall be tributary to surface infiltration or vegetative BMPs. Use of catchment facilities for the purpose of reuse is also permitted. When it is more advantageous to connect directly to streets or storm sewers, roof drain connections to streets or roadside ditches may be permitted on a case-by-case basis by the Borough. It shall be the burden of the person seeking to make the connection to demonstrate to the Borough that such connection is more advantageous and such connection shall not violate any state or federal statute, rule or regulation. Proposed storm sewer piping may connect to an existing storm sewer piping system, provided the existing storm sewer is adequate.
21. 
Nonstructural BMPs shall be utilized for all regulated activities unless proven to be impractical.
[Ord. 954, 12/19/2013]
Volume control BMPs are intended to maintain existing hydrologic conditions for small storm events by promoting groundwater recharge and/or evapotranspiration as described in this section. Runoff volume controls shall be implemented using the Design Storm Method described in Subsection A below, or through continuous modeling approaches or other means as described in the BMP Manual. Small projects may use the method described in Subsection B to design volume control BMPs.
A. 
The Design Storm Method is applicable to any size of regulated activity. This method requires detailed modeling based on site conditions.
(1) 
Do not increase the post-development total runoff volume for all storms equal to or less than the two-year, twenty-four-hour storm event.
(2) 
For modeling purposes:
(a) 
Existing (predevelopment), nonforested, pervious areas must be considered meadow in good condition.
(b) 
When the existing project site contains impervious area, 20% of existing impervious area to be disturbed shall be considered meadow in good condition in the model for existing conditions.
(c) 
The maximum loading ratio for volume control facilities in karst areas shall be 3:1 impervious drainage area to infiltration area and 5:1 total drainage area to infiltration area. The maximum loading ratio for volume control facilities in nonkarst areas shall be 5:1 impervious drainage area to infiltration area and 8:1 total drainage area to infiltration area. A higher ratio may be approved by the Borough if justification is provided. Hydraulic depth may be used as an alternative to an area-based loading ratio if the design hydraulic depth is shown to be less than the depth that could result from the maximum area loading ratio.
B. 
Volume Control for Small Projects. At least the first one inch of runoff from new impervious surfaces or an equivalent volume shall be permanently removed from the runoff flow, i.e., it shall not be released into the surface waters of this commonwealth. Removal options include reuse, evaporation, transpiration and infiltration.
C. 
A detailed geologic evaluation of the development site shall be performed in areas of carbonate geology to determine the design parameters of recharge facilities. A report shall be prepared in accordance with Section 504 of this chapter.
D. 
Storage facilities, including normally dry, open-top facilities, shall completely drain the volume control storage over a period of time not less than 24 hours and not more than 72 hours from the end of the design storm. Any designed infiltration at such facilities is exempt from the minimum twenty-four-hour standard, i.e., may infiltrate in a shorter period of time based on a field-tested infiltration rate, provided that none of this water will be discharged into waters of this commonwealth.
E. 
Any portion of the volume control storage that meets all of the following criteria may also be used as rate control storage:
(1) 
Volume control storage that depends on infiltration is designed according to the infiltration standards in § 301.
(2) 
The volume control storage which will be used for rate control is that storage which is available within 24 hours from the end of the design storm based on the stabilized infiltration rate and/or the evapotranspiration rate.
F. 
Volume control storage facilities designed to infiltrate shall avoid the least-permeable hydrologic soil group(s) at the development site.
[Ord. 954, 12/19/2013]
Rate control for large storms, up to the one-hundred-year event, is essential to protect against immediate downstream erosion and flooding.
A. 
Match Predevelopment Hydrograph. Applicants shall provide infiltration facilities or utilize other techniques which will allow the post-development one-hundred-year hydrograph to match the predevelopment one-hundred-year hydrograph for the development site. To match the predevelopment hydrograph, the post-development peak rate must be less than or equal to the predevelopment peak rate, and the post-development runoff volume must be less than or equal to the predevelopment volume for the same storm event.
B. 
Where the predevelopment hydrograph cannot be matched, the post-development discharge rates shall not exceed the predevelopment discharge rates for the two-, ten-, twenty-five-, fifty- and one-hundred-year, twenty-four-hour storm events.* If it is shown that the peak rates of discharge indicated by the post-development analysis are less than or equal to the peak rates of discharge indicated by the predevelopment analysis for two-, ten-, twenty-five, fifty- and one-hundred-year, twenty-four-hour storms,* then the requirements of this section have been met. Otherwise, the applicant shall provide additional controls as necessary to satisfy the peak rate of discharge requirement.
* A twenty-four-hour SCS Type II storm or an IDF Curve Rational Method storm. (See Table 3-1 in § 305.)
C. 
Normally dry, open-top, storage facilities shall completely drain the rate control storage over a period of time less than or equal to 24 hours from the peak one-hundred-year water surface design elevation.
D. 
A variety of BMPs should be employed and tailored to suit the development site. The following is a partial listing of BMPs which can be utilized in SWM systems for rate control where appropriate:
(1) 
Decreased impervious surface coverage.
(2) 
Routed flow over grass.
(3) 
Grassed channels and vegetated strips.
(4) 
Bioretention areas (rain gardens).
(5) 
Concrete lattice block or permeable surfaces.
(6) 
Seepage pits, seepage trenches or other infiltration structures.
(7) 
Rooftop detention.
(8) 
Parking lot detention.
(9) 
Cisterns and underground reservoirs.
(10) 
Amended soils.
(11) 
Retention basins.
(12) 
Detention basins.
(13) 
Other methods as may be found in the BMP Manual.
E. 
Small projects are not required to provide for rate control.
[Ord. 954, 12/19/2013]
1. 
Runoff from impervious areas shall be drained to pervious areas within the development site, unless the site has 85% or more impervious cover and is a redevelopment,10 in which case the portion of the site that discharges to pervious areas shall be maximized.
2. 
Stormwater runoff from a development site to an adjacent property shall flow directly into a natural drainageway, watercourse or into an existing storm sewer system or onto adjacent properties in a manner similar to the runoff characteristics of the predevelopment flow.
3. 
Stormwater flows onto adjacent property shall not be created, increased, decreased, relocated or otherwise altered without evidence of a written certified letter of notification to the adjacent property owner(s) by the developer. Such stormwater flows shall be subject to the requirements of this chapter, including the establishment of a drainage easement. Copies of all such notifications shall be included in land disturbance plan submission.
4. 
Existing on-site natural and man-made SWM facilities shall be used to the maximum extent practicable.
5. 
Stormwater runoff shall not be transferred from one subwatershed to another unless they are subwatersheds of a common watershed that join together within the perimeter of the development site and the effect of the transfer does not alter the peak discharge onto adjacent lands.
6. 
Minimum floor elevations for all structures that would be affected by a basin, other temporary impoundments, or open conveyance systems where ponding may occur shall be two feet above the one-hundred-year water surface elevation. If basement or underground facilities are proposed, detailed calculations addressing the effects of stormwater ponding on the structure and waterproofing and/or floodproofing design information shall be submitted for approval.
7. 
All stormwater-conveyance facilities (excluding detention, retention, and wetland basin outfall structures) shall be designed to convey a twenty-five-year storm event.* All stormwater-conveyance facilities (excluding detention, retention, and wetland basin outfall structures) conveying water originating from off site shall be designed to convey a fifty-year storm event.* The SWM report shall also provide calculations verifying the safe conveyance of the one-hundred-year runoff event* to appropriate peak rate control BMPs must be demonstrated in the design.
* A twenty-four-hour SCS Type II storm or an IDF Curve Rational Method storm.
8. 
Erosion protection shall be provided along all open channels and at all points of discharge. Flow velocities from any storm sewer may not result in erosion of the receiving channel.
[Ord. 954, 12/19/2013]
1. 
Any stormwater runoff calculations involving drainage areas greater than 200 acres and time of concentration (Tc) greater than 60 minutes, including on- and off-site areas, shall use generally accepted calculation techniques based on the NRCS Soil-Cover-Complex Method.
2. 
Stormwater runoff from all development sites shall be calculated using either the Modified Rational Method, a Soil-Cover-Complex Methodology, or other method acceptable to the Borough. Table 3-1 summarizes acceptable computation methods. It is assumed that all methods will be selected by the design professional based on the individual limitations and suitability of each method for a particular development site.
Table 3-1
Acceptable Computation Methodologies for Stormwater Management Plans
Method
Method Developed by
Applicability
TR-20 (or commercial computer package based on TR-20)
USDA NRCS
Applicable where use of full hydrology computer model is desirable or necessary
Win TR-55 (or commercial computer package based on TR-55)
USDA NRCS
Applicable for land development plans within limitations described in TR-55
HEC-1/HEC-HMS
U.S. Army Corps of Engineers
Applicable where use of full hydrologic computer model is desirable or necessary
Rational Method (or commercial computer package based on Rational Method)
Emil Kuichling (1889)
For development sites less than 200 acres, Tc<60 min. or as approved by the Borough
EFH2
USDA NRCS
Applicable in rural and undeveloped areas subject to the program limits
Other methods
Varies
Other methodologies approved by the Borough
3. 
If the SCS Method is used, Antecedent Moisture Condition 1 is to be used in areas of carbonate geology, and Antecedent Moisture Condition 2 is to be used in all other areas. A Type II distribution shall be used in all areas.
4. 
If the Rational Method is used, the National Oceanic and Atmospheric Administration (NOAA) Atlas 14 data (see Subsection 2 above) or PennDOT Publication 584, "PennDOT Drainage Manual," shall be used to determine the rainfall intensity in inches per hour based on the information for the five- through sixty-minute duration storm events. (Refer to Appendix B-3).[1]
[1]
Editor's Note: Appendix B is included as an attachment to this chapter.
5. 
Hydrographs may be obtained from NRCS methods such as TR-55, TR20 or from use of the "modified" or "unit hydrograph" rational methods. If "modified" or "unit hydrograph" rational methods are used, the ascending leg of the hydrograph shall have a length equal to three times the time of concentration (3 x Tc), and the descending leg shall have a length equal to seven times the time of concentration (7 x Tc) to approximate an SCS Type II hydrograph.11
6. 
Runoff calculations shall include a hydrologic and hydraulic analysis indicating volume and velocities of flow and the grades, sizes and capacities of water-carrying structures, sediment basins, retention and detention structures and sufficient design information to construct such facilities. Runoff calculations shall also indicate both predevelopment and post-development rates for peak discharge of stormwater runoff from all discharge points.
7. 
For the purpose of calculating predevelopment peak discharges, all runoff coefficients, both on-site and off-site, shall be based on actual land use assuming summer or good land conditions. Post-development runoff coefficients for off-site discharges used to design conveyance facilities shall be based on actual land use assuming winter or poor land conditions.
8. 
Criteria and assumptions to be used in the determination of stormwater runoff and design of management facilities are as follows:
A. 
Runoff coefficients shall be based on the information contained in Appendix B-1 and B-2 if the actual land use is listed in those appendixes.[2] If the actual land use is not listed in those appendixes, runoff coefficients shall be chosen from other published documentation, and a copy of said documentation shall be submitted with the SWM plan for review and approval by the Borough.
[2]
Editor's Note: Appendix B is included as an attachment to this chapter.
B. 
A sample worksheet for calculating Tc is provided in Appendix B-5.[3] Times of concentration (Tc) shall be based on the following design parameters or as calculated by an approved hydraulic program:
(1) 
Sheet Flow: The maximum length for each reach of sheet or overland flow before shallow concentrated or open channel flow develops is 150 feet. Flow lengths greater than 100 feet shall be justified based on the actual conditions at each development site. Sheet flow may be determined using the nomograph in Appendix B-4 or Manning's kinematic solution shown in the sheet flow section of Worksheet No. 1 in Appendix B-5.[4]
[4]
Editor's Note: Appendix B is included as an attachment to this chapter.
(2) 
Shallow Concentrated Flow: Travel time for shallow concentrated flow shall be determined using Figure 3-1 from TR-55, Urban Hydrology for small watersheds, as shown in Appendix B-6.[5]
[5]
Editor's Note: Appendix B is included as an attachment to this chapter.
(3) 
Open Channel Flow: At points where sheet and shallow concentrated flows concentrate in field depressions, swales, gutters, curbs or pipe collection systems, the travel times to the downstream end of the development site between these design points shall be based upon Manning's Equation and/or acceptable engineering design standards as determined by the Borough Engineer.
[3]
Editor's Note: Appendix B is included as an attachment to this chapter.
C. 
The developer may use stormwater credits for nonstructural BMPs in accordance with the BMP Manual. The allowable reduction will be determined by the Borough.
D. 
Peak rate control is not required for off-site runoff. Off-site runoff may be bypassed around the site, provided all other discharge requirements are met. If off-site runoff is routed through rate control facilities, runoff coefficients for off-site discharges used to design those rate control facilities shall be based on actual land use assuming winter or poor land conditions.
9. 
Times of concentration shall be calculated based on the methodology recommended in the respective model used. Tc for channel and pipe flow shall be computed using Manning's Equation. Supporting documentation and calculations must be submitted for review and approval.
[Ord. 954, 12/19/2013]
1. 
In order to protect and improve water quality, a riparian corridor easement shall be created and recorded as part of any subdivision or land development that encompasses a riparian corridor.
2. 
Except as otherwise required by Chapter 102, the riparian corridor easement shall be measured to be the greater of the limit of the one-hundred-year floodplain or 35 feet from the top of stream bank (on each side).
3. 
Minimum Management Requirements for Riparian Corridors.
A. 
Existing native vegetation shall be protected and maintained within the riparian corridor easement.
B. 
Whenever practicable, invasive vegetation shall be actively removed and the riparian corridor easement shall be planted with native trees, shrubs and other vegetation to create a diverse native plant community appropriate to the intended ecological context of the site.
4. 
The riparian corridor easement shall be enforceable by the Borough and shall be recorded in the Lancaster County Recorder of Deeds' office, so that it shall run with the land and shall limit the use of the property located therein. The easement shall allow for continued private ownership and shall count toward the minimum lot area as required by Chapter 27, Zoning.
5. 
Any permitted use (as listed below) within the riparian corridor easement shall be conducted in a manner that will maintain the extent of the existing one-hundred-year floodplain, improve or maintain the stream stability and preserve and protect the ecological function of the floodplain.
6. 
The following conditions shall apply when public and/or private recreation trails are permitted within riparian corridors:
A. 
Trails shall be for nonmotorized use only.
B. 
Trails shall be designed to have the least impact on native plant species and other sensitive environmental features.
7. 
Septic drainfields and sewage disposal systems shall not be permitted within the riparian corridor easement and shall comply with setback requirements established under 25 Pa Code Chapter 73.
[Ord. 954, 12/19/2013]
1. 
General.
A. 
For all aboveground storage facilities, the bottom of the excavated basin shall be a minimum of two feet or 24 inches above the seasonal high water table or bedrock, or other limiting zone. Soil sampling, test pits or auger testing must be completed in the proposed location of the facilities in support of the design.
B. 
Aboveground storage facilities without restricted access shall have impoundment areas with side slopes no greater than five horizontal to one vertical (5:1). Basins with side slopes steeper than five horizontal to one vertical (5:1) shall be protected by fencing that will discourage access.
C. 
Aboveground storage facilities with a facility depth greater than eight feet shall not be permitted in residential areas.
D. 
Aboveground storage facilities with a facility depth greater than 15 feet require a dam permit from DEP.
E. 
All pipe collars, when required, shall be designed in accordance with Chapter 7 of the E&S Manual. The material shall consist of concrete, or otherwise nondegradable material approved by the Borough Engineer, around the outfall barrel and shall be watertight.
F. 
The embankment fill material shall be taken from an appropriate borrow area, which shall be free of roots, stumps, wood, rubbish, stones greater than six inches, or frozen or other objectionable materials.
G. 
When required, embankments shall be compacted by sheepsfoot or pad roller. The loose lift thickness shall be nine inches or less, depending on roller size, and the maximum particle size is six inches or less (2/3 of the lift thickness). Five passes of the compaction equipment over the entire surface of each lift are required. Embankment compaction to visible nonmovement is also required.
H. 
The minimum bottom slope of facilities not designed for infiltration shall be 1%. A flatter slope may be used if an equivalent dewatering mechanism is provided.
I. 
When required, dewatering shall be provided through the use of underdrain, surface device or alternate approved by the Borough Engineer. If the facility is to be used for infiltration, the dewatering device should be capable of being disconnected and shall only be made operational if the basin is not dewatering within the required time frame.
J. 
When required, pretreatment elements shall consist of forebays, filter strips or alternate approved by the Borough Engineer, to keep silt to a smaller portion of the facility for ease of maintenance.
K. 
Within basins designed for infiltration, existing native vegetation shall be preserved, if possible. For existing unvegetated areas or for infiltration basins that require excavation, a planting plan shall be prepared, in accordance with § 301, Subsection 14, and the BMP Manual, which is designed to promote infiltration.
L. 
For facilities with a depth of two feet or greater, a Type D-W endwall or riser box outlet structure shall be provided.
M. 
For facilities with a depth less than two feet, no outlet structure is required.
N. 
All discharge control devices with appurtenances shall be made of reinforced concrete and stainless steel. Bolts/fasteners shall be stainless steel.
O. 
The spillway shall be designed to provide a nonerosive, stable condition when the project is completed.
P. 
The spillway shall be designed to convey the one-hundred-year post-development peak inflow when required.
Q. 
Freeboard shall be measured from the top of the water surface elevation in the spillway to the top of the berm for emergency use.
R. 
The Borough may require a breach analysis for basins based on site-specific conditions and concern of threat for downstream property. When required, the breach analysis shall be conducted in accordance with the NRCS methodology, the United States Army Corps of Engineers methodology (HEC-1) or other methodologies as approved by the Borough.
S. 
Embankment construction.
(1) 
An impervious core/key trench, when required, shall consist of a cutoff trench (below existing grade) and a core trench (above existing grade). A key trench may not be required wherever it can be shown that another design feature, such as the use of an impermeable liner, accomplishes the same purpose.
(2) 
Materials used for the core shall conform to the Unified Soil Classification GC, SC, CH, or CL and must have at least 30% passing the No. 200 sieve. The contractor shall provide the soils test results to the Borough.
(3) 
The dimensions of the core shall provide a minimum trench depth of two feet below existing grade, a minimum width of four feet and a side slope of 1H:1V or flatter.
(4) 
The core should extend up both abutments to the ten-year water surface elevation or six inches below the emergency spillway elevation, whichever is lower.
(5) 
The core shall extend four feet below any pipe penetrations through the impervious core. The core shall be installed along or parallel to the center line of the embankment.
(6) 
Compaction requirements shall be the same as those for the embankment to assure maximum density and minimum permeability.
(7) 
The core shall be constructed concurrently with the outer shell of the embankment.
(8) 
The trench shall be dewatered during backfilling and compaction operations.
2. 
Aboveground Storage Facilities. Aboveground storage facilities consist of all stormwater facilities which store, infiltrate/evaporate/transpire, clean or otherwise affect stormwater runoff and the top of which is exposed to the natural environment. Aboveground storage facilities are located above the finished ground elevation. Aboveground storage facilities do not include stormwater management facilities designed for conveyance or cisterns.
A. 
Design Criteria. Refer to Table 3-2, Aboveground Storage Facility Design Criteria.
(1) 
Facility with facility depth of less than two feet:
(a) 
The minimum top of embankment width shall be two feet.
(b) 
The maximum interior side slope shall be 2:1.
(c) 
The maximum exterior side slope shall be 2:1.
(d) 
The minimum outlet pipe diameter shall be six inches.
(e) 
Outlet pipe material shall be PVC, HDPE or RCP.
(f) 
An anticlogging device is required in the outlet structure.
(g) 
The spillway freeboard shall be a minimum of three inches.
(h) 
The spillway may be used to route the one-hundred-year storm.
(2) 
Facility with depth of two to eight feet:
(a) 
The embankment minimum top width shall be five feet.
(b) 
The maximum interior side slope shall be 5:1.
(c) 
The maximum exterior side slope shall be 3:1.
(d) 
A key trench and antiseep collar shall be provided.
(e) 
Compaction density testing of the embankment is required. Test logs shall be provided to the Borough as part of the inspection requirements.
(f) 
A dewatering feature is required.
(g) 
Pretreatment filtering of runoff prior to entering the facility is required.
(h) 
The minimum outlet pipe diameter shall be 12 inches.
(i) 
Outlet pipe material shall be HDPE or RCP.
(j) 
An anticlogging device is required in the outlet structure.
(k) 
The outlet structure is required to have an antivortex design.
(l) 
Watertight joints shall be provided.
(m) 
The spillway freeboard shall be a minimum of six inches.
(n) 
The minimum spillway width is 10 feet, and the maximum spillway width is 50 feet.
(o) 
The downstream channel into which the spillway discharges shall be checked for adequate capacity and stability.
(p) 
The spillway shall not be considered to function as part of the primary outlet structure and shall be only for emergency situations.
(3) 
Facility with depth greater than eight feet:
(a) 
The embankment minimum top width shall be eight feet.
(b) 
The maximum interior side slope shall be 5:1.
(c) 
The maximum exterior side slope shall be 3:1.
(d) 
A key trench and antiseep collar shall be provided.
(e) 
Compaction density testing of the embankment is required. Test logs shall be provided to the Borough as part of the inspection requirements.
(f) 
A dewatering feature for the facility is required.
(g) 
Pretreatment filtering of runoff prior to entering the facility is required.
(h) 
The minimum outlet pipe diameter is 15 inches.
(i) 
Outlet pipe material shall be RCP.
(j) 
An anticlogging device is required in the outlet structure.
(k) 
The outlet structure is required to have an antivortex design as required.
(l) 
Watertight joints shall be provided.
(m) 
The spillway freeboard shall be a minimum of 12 inches.
(n) 
The minimum spillway width is 20 feet; the maximum spillway width is 50 feet.
(o) 
The downstream channel into which the spillway discharges shall be checked for adequate capacity and stability.
(p) 
The spillway shall not be considered to function as part of the primary outlet structure and shall be only for emergency situations.
(4) 
General Requirements for Aboveground Storage Facilities:
(a) 
Where practical, the spillway shall be constructed in undisturbed ground.
(b) 
The effect on the downstream areas if the facility embankment fails shall be considered in the design of all facilities. Where possible the facility shall be designed to minimize the potential damage caused by such failure of the embankment.
(c) 
For all aboveground facilities that do not rely on infiltration to dewater the runoff, a flow path length-to-width ratio of 2:1 shall be provided to maximize the treatment time between the inflow point and the outlet structure.
Table 3-2
Aboveground Storage Facility Design Criteria
Facility Depth
Less than 2 Feet
2 Feet to 8 Feet
Greater than 8 Feet
Embankment Geometry
Top width (minimum)
2 feet
5 feet
8 feet
Interior side slope (maximum)
2:1
5:1
5:1
Exterior side slope (maximum)
2:1
3:1
3:1
Embankment construction
Key trench
Not required
Required
Required
Pipe collar
Not required
Required
Required
Compaction density
Not required
Required
Required
Internal Construction
Dewatering feature
N/A
Required
Required
Pretreatment elements
Not required
Required
Required
Outlet Structure
Pipe size (minimum)
6 inches
12 inches
15 inches
Pipe material
HDPE, PVC, RCP
HDPE, RCP
RCP
Anticlogging devices
Required
Required
Required
Antivortex design
Not required
Required
Required
Watertight joints in piping
No
Yes
Yes
Spillway Requirements
Spillway freeboard (minimum)
3 inches
6 inches
12 inches
Width (minimum)
Not required
10 feet
20 feet
Width (maximum)
Not required
50 feet
50 feet
Spillway channel design
Not required
Required
Required
Routing of 100-year storm
Permitted
Not permitted
Not permitted
3. 
Subsurface Storage Facilities. Subsurface storage facilities consist of all SWM facilities which store, infiltrate/evaporate/transpire, clean or otherwise affect stormwater runoff and the top of which is not exposed to the natural environment. Subsurface facilities are located below the finished ground elevation. Subsurface facilities do not include SWM facilities designed for conveyance.
A. 
General.
(1) 
The stone used for infiltration beds shall be clean washed, uniformly graded coarse aggregate (AASHTO No. 3 or equivalent approved by the Borough). The void ratio for design shall be assumed to be 0.4.
(2) 
Material consistency and placement depths for backfill shall be (at a minimum) per all applicable pipe manufacturer's recommendations, further providing it should be free of large (not exceeding six inches in any dimension), objectionable or detritus material. Select nonaggregate material should be indigenous to the surrounding soil material for nonvehicular areas. Backfill within vehicular areas shall comply with this section unless otherwise specified in Chapter 21, Streets and Sidewalks, or Chapter 22, Subdivision and Land Development. Furthermore, if the design concept includes the migration of runoff through the backfill to reach the infiltration facility, the material shall be well-drained, free of excess clay or clay-like materials and generally uniform in gradation.
(3) 
Nonwoven geotextiles shall be placed on the sides and top of subsurface infiltration facilities. No geotextiles shall be placed on the bottom of subsurface infiltration facilities.
(4) 
When located under pavement, the top of the subsurface facility, facility piping or conveyance shall be a minimum of six inches below the bottom of the pavement subbase. Where located under vegetative cover, the top of the subsurface facility shall be a minimum of 12 inches below the surface elevation or as required to establish vegetation.
(5) 
Subsurface facilities shall be designed to safely convey and/or bypass flows from storms exceeding the design storm.
B. 
Design Criteria. Refer to Table 3-3, Subsurface Storage Facility Design Criteria.
(1) 
Infiltration and Storage Facility:
(a) 
Maximum depth from surface: two feet less than limiting zone.
(b) 
Loading ratio: per December 2006 BMP Manual, as amended. The maximum impervious loading ratio is 5:1 relating impervious drainage area to infiltration area. The maximum total loading ratio is 8:1 relating to total drainage area to infiltration area. In areas of karst geology, the maximum impervious drainage area to infiltration area is 3:1.
(c) 
The minimum distribution pipe size shall be four inches. Distribution system piping may be PVC or HDPE.
(d) 
Pretreatment of runoff to the facility is required to provide a method to eliminate solids, sediment, and other debris from entering the subsurface facility.
(e) 
Observation/access ports shall be provided in the facility. For facilities with the bottom less than 12 feet below the average grade of the ground surface, a cleanout shall be an acceptable observation port. For facilities with the bottom 12 feet or more below the average grade of the ground surface, a manhole or other means acceptable to the Borough shall be provided for access to and monitoring of the facility. The number of access points shall be sufficient to flush or otherwise clean out the system.
(f) 
The facility shall be designed to provide a means of evenly balancing the flow across the surface of the facility to be used for infiltration.
(2) 
Storage Without Infiltration Facility.
(a) 
The minimum distribution pipe size shall be four inches. Distribution system piping may be PVC, HDPE or RCP.
(b) 
Pretreatment of runoff to the facility is required to provide a method to eliminate solids, sediment, and other debris from entering the subsurface facility.
(c) 
Observation/access ports shall be provided in the facility. For facilities with the bottom less than 12 feet below the average grade of the ground surface, a cleanout shall be an acceptable observation port. For facilities with the bottom 12 feet or more below the average grade of the ground surface, a manhole or other means acceptable to the Borough shall be provided for access to and monitoring of the facility. The number of access points shall be sufficient to flush or otherwise clean out the system.
Table 3-3
Subsurface Storage Facility Design Criteria
Facility Type
Infiltration and Storage
Storage without Infiltration
Facility Geometry
Depth from surface (maximum)
2 feet less than limiting zone
N/A
Loading ratio (maximum)
Per BMP Manual*
N/A
Distribution System Requirements
Pipe size (minimum)
4 inches
4 inches
Pretreatment
Required
Required
Loading/balancing
Required
Not required
Observation/access ports
Required
Required
NOTES:
*Unless otherwise determined by professional geologic evaluation.
4. 
Conveyance Facilities. Conveyance facilities consist of all SWM facilities which carry flow, which may be located either above or below the finished grade. Conveyance facilities do not include SWM facilities which store, infiltrate/evaporate/transpire, or clean stormwater runoff.
A. 
General.
(1) 
Conveyance pipes, culverts, manholes, inlets and endwalls within the public street right-of-way or proposed for dedication shall conform to the requirements of PennDOT Standards for Roadway Construction, Publication No. 72M.
(2) 
Conveyance pipes, culverts, manholes, inlets and endwalls which are otherwise subject to vehicular loading shall be designed for the HS-25 loading condition.
(3) 
Backfill Material. Material consistency and placement depths for backfill shall be (at a minimum) per all applicable pipe manufacturer's recommendations, further providing it should be free of large (not exceeding six inches in any dimension), objectionable or detritus material. Select nonaggregate material should be indigenous to the surrounding soil material for nonvehicular areas. Backfill within vehicular areas shall comply with this section unless otherwise specified in governing municipal road/street or subdivision and land development ordinances.
(4) 
Inlets or manholes shall be placed at all points of changes in the horizontal or vertical directions of conveyance pipes. Curved pipe sections are prohibited.
(5) 
Access/maintenance ports. An access/maintenance port is required and may either be an inlet or manhole.
(6) 
Watertight joints shall be provided where pipe sections are joined, except for perforated pipe installed as pavement base drain.
(7) 
Elliptical pipe of an equivalent cross-sectional area may be substituted in lieu of circular pipe where cover or utility conflict conditions exist.
(8) 
The roughness coefficient (Manning's "n" values) used for conveyance pipe capacity calculations should be determined in accordance with the manufacturer's specifications or with PennDOT Publication 13M, Design Manual, Part 2, Highway Design, Chapter 10, Appendix 4, as included below in Table 3-4.
Table 3-4
Roughness Coefficient "n" for Manning's Equation
Manning's "n"
Types of Pipe
0.010
Polyvinyl chloride (PVC) with smooth inner walls
0.012
Porous cement concrete pipe; corrugated high-density polyethylene (HDPE) with smooth inner walls
0.015
Corrugated high-density polyethylene (HDPE) with corrugated inner walls
(9) 
All pipes must enter inlets completely through one of the sides. No corner entry of pipes is permitted.
(10) 
Within the public street right-of-way, the gutter spread based on the twenty-five-year storm shall be no greater than 1/2 of the travel lane and shall have a maximum depth of three inches at the curbline. A parking lane shall not be considered as part of the travel lane. In the absence of pavement markings separating a travel lane from the parking lane, the parking lane shall be assumed to be seven feet wide if parking is permitted on the street.
(11) 
Flow Depth Within Intersections. Within intersections of streets, the maximum depth of flow shall be 1 1/2 inches based on the twenty-five-year storm.
(12) 
Inlets in streets shall be located along the curbline and have PennDOT Type C top units. The hood shall be aligned with the adjacent curb height accounting for the required two-inch inlet sump.
(13) 
All inlets placed in paved areas shall have heavy-duty, bicycle-safe grating consistent with PennDOT Publication 72M. A note to this effect shall be added to the SWM site plan or inlet details therein.
(14) 
Inlets, junction boxes, or manholes greater than five feet in depth shall be detailed on the SWM site plan.
(15) 
A swale shall be considered as any man-made ditch designed to convey stormwater directly to another SWM facility or surface waters.
(16) 
Inlets within swales shall have PennDOT Type M top units or equivalent approved by the Borough Engineer.
(17) 
Swale capacities and velocities shall be computed using the Manning Equation using the following design parameters:
(a) 
Vegetated Swales.
[1] 
The first condition shall consider swale stability based upon a low degree of retardance ("n" = 0.03);
[2] 
The second condition shall consider swale capacity based upon a higher degree of retardance ("n" = 0.05); and
[3] 
All vegetated swales shall have a minimum slope of 1% unless otherwise approved by the Borough Engineer.
[4] 
The "n" factors to be used for paved or riprap swales or gutters shall be based upon accepted engineering design practices, as approved by the Borough Engineer.
(18) 
Trash racks shall be provided on all endwalls and storm sewer discharge points for pipe diameters of 18 inches of greater. The proposed trash rack shall be subject to review and approval by the Borough. Such protection devices shall be designed to be removable for cleaning.
(19) 
Headwalls and endwalls shall be constructed of concrete.
(20) 
Flared end sections shall be of the same material as the connecting pipe and shall be designed for the size of the connecting pipe.
(21) 
Level spreaders:
(a) 
Shall discharge at existing grade onto undisturbed vegetation.
(b) 
Shall discharge at a depth not exceeding 3.0 inches for a fifty-year, twenty-four-hour design storm.
(22) 
Energy dissipaters shall be designed in accordance with the requirements in the E&S Manual.
(23) 
SWM facilities which qualify as a dam per DEP regulations or facilities deemed a potential threat to the life, safety or welfare of the general public shall be subject to the following requirements:
(a) 
Facilities which qualify as a dam per DEP regulation shall obtain the required permit through the DEP and design the facility in accordance with DEP standards.
(b) 
Additional requirements and analysis may be required by the Borough to prove that the proposed facility has been designed to limit the potential risk to the life, safety or welfare of the general public.
(24) 
In addition to the material requirements in this section, culverts designed to convey waters of the commonwealth may be constructed with either a corrugated metal arch or a precast concrete culvert pending DEP approval of the necessary permit(s).
B. 
Design Criteria. Refer to Table 3-5, Conveyance Facility Design Criteria.
(1) 
Within a public street right-of-way:
(a) 
Conveyance system material shall consist of HDPE or RCP pipe.
(b) 
The minimum pipe slope shall be 0.5%.
(c) 
A minimum one foot of cover to the stone subgrade shall be provided over the conveyance pipes in paved or vehicular areas; in grassed areas, a minimum pipe cover of one foot shall be provided.
(d) 
The minimum pipe diameter shall be 15 inches.
(e) 
The minimum street-crossing angle for the conveyance system shall be 75° to 90°. The street-crossing angle shall be measured between the pipe center line and the street center line.
(f) 
The maximum spacing between access or maintenance ports shall be 400 feet.
(g) 
Inlets and manholes shall be concrete.
(h) 
Inlets shall be depressed a minimum of two inches below the surface grade to provide positive flow.
(i) 
Swales shall be provided with a minimum freeboard of six inches.
(j) 
The maximum swale velocity shall be determined based on the stability of the channel.
(k) 
The minimum allowable swale slope shall be 1%.
(l) 
Swale side slopes in residential and nonresidential areas shall be a maximum of 4:1.
(m) 
The bottom width to flow depth ratio in any swale shall be 12:1.
(n) 
Pipe entrances/discharges in public street rights-of-way shall be provided with a headwall/endwall treatment or equivalent as approved by the Borough.
(o) 
The conveyance system discharge locations shall be provided with an energy dissipater designed to handle the anticipated flow conditions. The supporting design calculations shall be provided in the stormwater management report.
(2) 
Outside public street right-of-way: vehicular loading.
(a) 
Conveyance system material shall consist of PVC, HDPE or RCP pipe.
(b) 
The minimum pipe slope shall be 0.5%.
(c) 
A minimum one foot of cover to the stone subgrade shall be provided over the conveyance pipes.
(d) 
The minimum pipe diameter shall be 15 inches.
(e) 
The maximum spacing between access or maintenance ports shall be 400 feet.
(f) 
Inlets and manholes shall be constructed of concrete.
(g) 
Inlets shall be depressed a minimum of two inches below the surface grade to provide positive flow.
(3) 
Outside public street right-of-way: nonvehicular loading.
(a) 
Conveyance system material shall consist of PVC, HDPE or RCP pipe.
(b) 
The minimum pipe slope shall be 0.5%.
(c) 
A minimum one foot of cover to the surface shall be provided over the conveyance pipes.
(d) 
The minimum pipe diameter shall be eight inches.
(e) 
Maximum spacing between access or maintenance ports shall be 400 feet.
(f) 
Manholes shall be constructed of concrete.
(g) 
Inlets shall be depressed a minimum of one inch below the surface grade to provide positive flow.
(h) 
Swales shall be provided with a minimum freeboard of six inches.
(i) 
The maximum swale velocity shall be determined based on the stability of the channel.
(j) 
The minimum swale slope (longitudinal) shall be 1%.
(k) 
Swale side slopes in residential areas shall be a maximum of 4:1, and a maximum of 3:1 in nonresidential areas.
(l) 
The bottom width to flow depth ratio in swales shall be 12:1.
(m) 
Pipe entrances/discharges in public street rights-of-way shall be provided with a headwall/endwall or flared end section treatment.
(n) 
The conveyance system discharge locations shall be provided with an energy dissipater designed to handle the anticipated flow conditions.
Table 3-5
Conveyance Facility Design Criteria
Location
Within Public Street Right-of-Way
Outside Public Street Right-of-Way
Loading
All
Vehicular Loading
Nonvehicular Loading
Pipe design
Material
HDPE, RCP
PVC, HDPE, RCP
PVC, HDPE, RCP
Slope (minimum)
0.5%
0.5%
0.5%
Cover
1 foot to stone subgrade
1 foot to stone subgrade
1 foot to surface
Diameter (minimum)
15 inches
15 inches
8 inches
Street-crossing angle
75° to 90°
N/A
N/A
Access/ maintenance port frequency (maximum)
400 feet
400 feet
400 feet
Inlet design
Material
Concrete
Concrete
N/A
Grate depression
2 inches
2 inches
1-inch minimum
Manhole design
Material
Concrete
Concrete
Concrete
Swale design
Freeboard (minimum)
6 inches
N/A
6 inches
Velocity (maximum)
Stability check
N/A
Stability check
Slope (minimum)
1%
N/A
1%
Side slopes (residential area)
4:1 max
N/A
4:1 max
Side slopes (nonresidential area)
4:1 max
N/A
3:1 max
Bottom width to flow depth ratio
12:1
N/A
12:1
Outlet design
End treatment
Headwall/ endwall
N/A
Headwall/ endwall or flared end section
Energy dissipater
Required
N/A
Required
5. 
Capture and Reuse Facilities.
A. 
Design Requirements:
(1) 
Calculation of water usage to ensure adequate capacity is available for storage of follow-up rainfall events. The property will draw from the cistern on a daily basis; the cistern shall be dewatered in 72 hours to maintain the capacity of the storage facility. This shall be noted on the plan and maintenance agreement.
(2) 
Verification of conveyance pipe capacity in the roof leader design shall be provided in the stormwater management report.
(3) 
The stormwater runoff storage container(s) shall be protected from direct sunlight to minimize algae growth.
(4) 
An alternative supply of water shall be available for the property use during dry periods if the reuse facility is used for supplying the dwelling with water.
(5) 
Stormwater runoff storage containers should be watertight with smooth interior surfaces.
(6) 
The cover (or lid) should have a tight fit to keep out surface water, children, animals, dust and light. The cover or lid opening should be a minimum 24 inches in order to access the facility for maintenance and repair.
(7) 
Cisterns shall be designed to store the runoff volume of a one-hundred-year storm event for the area served by the stormwater runoff storage facility.
(8) 
Every stormwater runoff storage facility (cistern, rain barrel, etc.) shall be provided with an overflow or an emergency outlet. The overflow shall be designed to discharge away from buildings and other structures and towards existing natural or man-made channels, stormwater facilities or vegetated slopes.
(9) 
The plans proposing a water storage facility shall include the following:
(a) 
All calculations and assumptions used in the design.
(b) 
Sufficient detail showing the proposed method of dewatering (i.e., pump).
(c) 
Structural details.
(10) 
Maintenance responsibilities for water storage and reuse facilities shall include flushing the storage units to remove any accumulated sediment; the inside surfaces shall be brushed and thoroughly disinfected.
(11) 
The stormwater runoff collected shall not be allowed to freeze in the devices.
[Ord. 954, 12/19/2013]
1. 
The applicant must comply with the erosion control rules and regulations of Chapter 102.
2. 
The design plan and construction schedule shall incorporate measures to prevent soil erosion and sedimentation.
3. 
The following principles shall be applied to the design plan and construction schedule to minimize soil erosion and sedimentation:
A. 
Erosion and sedimentation controls designed in conformance with the E&S Manual shall be implemented during the construction and post-construction periods to prevent soil erosion, sedimentation and other pollutants from entering streams, lakes, etc.
B. 
Natural vegetation shall be retained and protected on all undisturbed areas.
C. 
The extent of the disturbed area and the duration of its exposure shall be kept to a minimum. Stockpiles to remain in place longer than 20 days shall be seeded.
D. 
It shall be the applicant's responsibility during construction to prevent soil pollution to neighboring property, public streets, and streams. Soil dropped from construction equipment and sedimentation shall be immediately removed from roads, public and private property, and streams.
E. 
Drainage provisions shall accommodate the stormwater runoff both during and after construction.
F. 
Soil erosion and sedimentation facilities shall be installed prior to any on-site earth disturbances.
4. 
The developer shall maintain a copy of the erosion and sedimentation control plan and notes on site during construction.