[Amended 9-26-2022 by Ord. No. 2022-4]
A. 
For all regulated activities, unless preparation of an SWM site plan is specifically exempted in § 252-11:
(1) 
Preparation and implementation of an approved SWM site plan is required.
(2) 
No regulated activities shall commence until the Township issues written approval of an SWM site plan which demonstrates compliance with the requirements of this chapter.
B. 
SWM site plans approved by the Township, in accordance with § 252-26, shall be on site throughout the duration of the regulated activity.
C. 
The Township may, after consultation with 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 Township shall maintain a record of consultations with DEP pursuant to this subsection. Where the Township identifies a potential water quality issue raised by an application or project, the application or project information will be forwarded to PA DEP for consultation, along with the proposed Township decision on the application or project. If the Township does not receive a response from PA DEP within 15 business days from DEP receipt, the Township will issue its decision to the applicant noting that the PA DEP has not responded to the consultation.
(1) 
DEP is not required to be consulted for waiver of the requirements within:
(a) 
Section 252-15, Design criteria.
(b) 
Section 252-16, Regulations governing stormwater management facilities.
(c) 
Section 252-17, Calculation methodology.
(d) 
Section 252-18, Carbonate geology.
(e) 
Section 252-19, Erosion and sedimentation control requirements.
D. 
For all regulated earth disturbance activities, erosion and sediment control BMPs shall be designed, implemented, operated, and maintained during the regulated earth disturbance activities, i.e., during construction, 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 Erosion and Sediment Pollution Control Program Manual (E&S Manual) 2, No. 363-2134-008 (April 15, 2000), as amended and updated.
E. 
For all regulated activities, implementation of the volume controls in § 252-12 is required, unless specifically exempted under § 252-11, or exempted by an approved modification request as specified in § 252-23B of this chapter.
F. 
Impervious areas.
(1) 
The measurement of impervious areas shall include all of the impervious areas in the total proposed development even if development is to take place in phases.
(2) 
For development taking place in phases, the entire development plan must be used in determining conformance with this chapter.
(3) 
For projects that add impervious area to a parcel, the total impervious area on the parcel is subject to the requirements of this chapter; except that the volume controls in § 252-12, especially Subsection A(2)(b), and the peak rate controls of § 252-13, especially Subsection A, do not need to be retrofitted to existing impervious areas that are not being altered by the proposed regulated activity. An existing impervious area is considered to be altered when it is physically changed by the proposed regulated activity, except that maintenance work of an existing impervious surface (i.e. repaving, reroofing, etc.) shall not be considered alteration.
G. 
Stormwater flows onto adjacent property shall not be created, increased, decreased, relocated, or otherwise altered without written notification of the adjacent property owner(s). Such stormwater flows shall be subject to the requirements of this chapter.
H. 
All regulated activities shall include such measures as necessary to:
(1) 
Protect health, safety, and property;
(2) 
Meet the water quality goals of this chapter, as stated in § 252-3, Purpose, by implementing measures to:
(a) 
Minimize disturbance to floodplains, wetlands, wooded areas, and existing vegetation.
(b) 
Maintain or extend riparian buffers.
(c) 
Avoid erosive flow conditions in natural flow pathways.
(d) 
Minimize thermal impacts to waters of this commonwealth.
(e) 
Disconnect impervious surfaces by directing runoff to pervious areas, wherever possible.
(f) 
Minimize soil disturbance and compaction. Topsoil, if removed, shall be replaced to a minimum depth equal to its depth prior to removal or four inches, whichever is greater. (Additional topsoil may be needed for vegetation other than sod.)
(3) 
Incorporate methods described in the Pennsylvania Stormwater Best Management Practices Manual (BMP Manual, see § 252-45C). If methods other than green infrastructure and LID methods are proposed to achieve the volume and rate controls required under this chapter, the SWM site plan must include a detailed justification demonstrating that the use of LID and green infrastructure is not practicable.
I. 
The design of all facilities in areas of carbonate geology or karst topography shall include an evaluation of measures to minimize adverse effects, including hydrogeologic studies if required by the Township.
J. 
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. In addition, infiltration BMPs shall include pretreatment BMPs where appropriate.
K. 
All natural streams, channels, swales, drainage systems and/or areas of surface water concentration shall be maintained in their existing condition unless an alteration is approved by the Township. All encroachment activities shall comply with the requirements of PA DEP 25 Pa. Code Chapter 105 (Water Obstructions and Encroachments), Rules and Regulations of PA DEP. Any approvals or permits issued do not relieve compliance as referenced in § 252-6, Compatibility with other permit and ordinance requirements.
L. 
All stormwater management facilities (excluding individual residential underground infiltration facilities) are considered structures and must comply with building setback requirements. The outside toe of slope of the embankment in a fill condition or the top of embankment in a cut condition shall be considered as the point that must meet the setback requirements. Individual residential underground infiltration facilities shall be a minimum of 10 feet from the property line. Discharge of controlled flows can be no closer to an adjacent property than two times the length of the required discharge rip-rap apron. This requirement applies to discharge aprons that do not outlet to a defined waterway or an existing storm sewer. Minimum distance is 10 feet.
M. 
All storage facilities shall completely drain both the volume control and rate control capacities over a period of time not less than 24 hours and not more than 72 hours from the end of the design storm. However, 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, so long as none of the stormwater flowing into the infiltration facility is discharged directly into the surface waters of the commonwealth. (Inordinately rapid infiltration rates may indicate the presence of large fractures or other conditions for which an additional soil buffer may be required.)
N. 
The design storm volumes and precipitation intensities to be used in the analysis of discharge or runoff shall be obtained from the Precipitation-Frequency Atlas of the United States, Atlas 14, Volume 2, Version 3.0, U.S. Department of Commerce, National Oceanic and Atmospheric Administration (NOAA), National Weather Service, Hydrometeorological Design Studies Center, Silver Spring, Maryland. NOAA's Atlas 14 website is provided in Appendix D.[1]
[1]
Editor's Note: Appendix D is included as an attachment to this chapter.
O. 
For all regulated activities, SWM 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, the Clean Streams Law, and the Stormwater Management Act.
P. 
Various BMPs and their design standards are listed in the BMP Manual.
Q. 
All work shall be in accordance with the Township's Construction and Material Specifications.
R. 
The technical standards provided within this chapter are considered the baseline for the design and layout of an SWM site plan. Use of other alternative and innovative designs for controlling stormwater runoff may be permitted when approved by the Township Engineer.
[Amended 1-25-2016 by Ord. No. 2016-1; 9-26-2022 by Ord. No. 2022-4]
Any regulated activity that meets the following exemption criteria is exempt from the part(s) of this chapter as specified herein. However, the requirements of the chapter shall otherwise remain in effect. The criteria for exemption in this section apply to the total development proposed, including instances in which the development is proposed to take place in phases. The date of enactment of this chapter shall be the starting point from which future development and the respective proposed impervious surface computations shall be cumulatively considered and regulated. Exemption shall not relieve an applicant from implementing such measures as necessary to meet the intent of this chapter, or compliance with any NPDES permit requirements.
A. 
Regulated activities.
(1) 
Small projects. Regulated activities that propose less than 400 square feet of additional impervious area may be fully exempt and a fee in lieu may be paid. Refer to Appendix C hereto to determine the requirements for exempt small projects, as defined by Appendix C.[1]
[1]
Editor's Note: Appendix C is included as an attachment to this chapter.
(2) 
Regulated activities for residential uses: For the first 400 square feet of new impervious area, created after the enactment date of this Part, a credit shall be granted subject to Subsection A above, whereby the regulated activity is exempt from the requirements of this Part. For the next 600 square feet of new impervious area, created after the enactment date of this Part, the regulated activity is subject only to the volume control requirements of this Part; therefore, a simplified stormwater management permit application to Fairview Township is required. The Township may elect to adopt by resolution, modified requirements for small projects. Under these regulations, regulated activities that involve up to 1,000 square feet of proposed impervious surfaces may apply the modified requirements presented in the "Simplified Approach to Stormwater Management for Small Projects" (simplified approach) to comply with the requirements of this chapter.
(3) 
Regulated activities that create disconnected impervious areas (DIAs) greater than 1,000 square feet and equal to or less than 5,000 square feet are exempt only from the peak rate control requirement of this chapter, the regulated activity is subject only to the plan preparation and volume control requirements of this Part.
(4) 
Applicants proposing regulated activities which qualify as a DIA with the availability of minimum separation distances are exempted from various requirements of this chapter according to the following table and regulations:
Minimum Separation Distances
New Impervious Area
(square feet)
Minimum Separation Distance
(feet)
Sheet Flow
Roof Drain
0 to 250
See Appendix B
See Appendix B
251 to 400
See Appendix B
See Appendix B
401 to 1,000
75
110
1,001 to 1,500
100
150
1,501 to 2,000
125
190
2,001 to 2,500
150
225
2,501 to 3,000
175
260
3,001 to 4,000
200
300
4,001 to 5,000
225
340
A roof with no roof drain is sheet flow. Where Fairview Township believes that conditions present in the receiving area (due to slope, soil type, existing drainage problems, etc.) warrant additional separation distance, Fairview Township may require additional separation distance or require stormwater management controls.
(a) 
Minimum separation.
[1] 
New impervious cover shall be separated from the features listed in § 252-11A(3)(a)[2] below and in accordance with the minimum separation distances listed in the table above.
[2] 
Minimum separation distance is the shortest distance from the edge of the proposed new impervious cover, or roof drain discharge point, in the flow direction of runoff, to any of the following:
[a] 
Perennial or intermittent streams or watercourses;
[b] 
Swales or ditches;
[c] 
Wetlands;
[d] 
Lakes, ponds, and other surface water bodies;
[e] 
Storm sewer or combined sewer systems;
[f] 
Public roads;
[g] 
Property lines;
[h] 
Cropland, pastureland, manure storage areas and other agricultural land;
[i] 
Other features deemed relevant by Fairview Township.
(b) 
Multiple impervious areas.
[1] 
If the proposed new impervious area receives runoff from an existing contiguous impervious area or contributes runoff to an existing contiguous impervious area, the total impervious area to be considered for this exemption shall be the new impervious area only.
[2] 
If the existing and proposed new impervious areas are not contiguous, the total impervious area to be considered for this exemption shall be the new impervious area only. In this case, the total separation areas may include the distance between two impervious areas.
[3] 
Separation from the features listed in § 252-11A(3)(a)[2] shall be determined from the edge or roof drain discharge, of either the existing or the proposed new impervious area, whichever is the most downslope.
[4] 
Fairview Township reserves the right to consider existing conditions and run-off issues in determining the needed separation area under this section.
(c) 
Discharge.
[1] 
With the exception of roof drains, runoff from the proposed new impervious cover may not be concentrated. Roof drains:
[a] 
Must discharge to a stabilized separation area meeting the criteria in the above table for minimum separation distance shown above and § 252-11A(3).
[b] 
May not discharge to concentrated flow areas. Separation shall be determined from the roof drain discharge point unless the discharge is to an impervious area. In this case the separation shall be determined from the edge of the pervious area.
(d) 
Separation area.
[1] 
The area separating the proposed new impervious discharge from any features such as those listed in § 252-11A(3)(a)[2] must always meet the following criteria:
[a] 
Be maintained in stable vegetative cover.
[b] 
Eroded areas in the separation area must be immediately repaired.
[c] 
No new impervious cover may be installed in the separation areas unless the requirements of this chapter are met.
[d] 
Runoff in the separation area must be maintained as unconcentrated flow.
[2] 
The separation area may contain cropland, pastureland, manure storage areas and other agricultural land provided the land is in compliance with Title 25, Chapter 102.4.a (relating to erosion and sediment pollution control on agricultural land), and Title 25, Chapter 91.36.a (relating to pollution control at agricultural operations), of The Pennsylvania Code.
(e) 
Obligation to meet other requirements.
[1] 
Nothing in this section shall relieve the applicant of any responsibility under other regulations such as, but not limited to, municipal ordinances or codes and state and federal regulations related to stormwater management, NPDES permitting requirements for erosion and sediment pollution control and post-construction stormwater management, stream and wetland encroachment or floodplain management.
B. 
Agricultural activity is exempt from the rate control and SWM site plan preparation requirements of this chapter, provided the activities are performed according to the requirements of 25 Pa. Code § 102. For regulated activities that meet this exemption criteria, no formal application to the Township is required.
C. 
Forest management and timber operations are exempt from the rate control and SWM site plan preparation requirements of this chapter provided the activities are performed according to the requirements of 25 Pa. Code § 102. For regulated activities that meet this exemption criteria, no formal application to the Township is required.
D. 
Domestic gardening and landscaping are exempt from specific approval and permitting under this chapter so long as those activities are associated with one, and only one, dwelling unit and the activities comply with all other applicable ordinances and statutes.
E. 
Exemptions from certain provisions of this chapter shall not relieve the applicant from the requirements in § 252-10D through N.
F. 
The Township may deny or revoke any exemption pursuant to this section at any time for any project that the Township determines poses a threat to public health, safety, property or the environment.
[Amended 9-26-2022 by Ord. No. 2022-4]
The green infrastructure and low impact development practices provided in the BMP Manual, see § 252-45C, shall be utilized for all regulated activities wherever possible. Water volume controls shall be implemented using the Design Storm Method in Subsection A or the Simplified Method in Subsection B below. For regulated activity areas equal or less than one acre that do not require hydrologic routing to design the stormwater facilities, this chapter establishes no preference for either methodology; therefore, the applicant may select either methodology on the basis of economic considerations, the intrinsic limitations on applicability of the analytical procedures associated with each methodology and other factors.
A. 
The Design Storm Method (CG-1 in the BMP Manual, see § 252-45C) 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 duration precipitation.
(2) 
For modeling purposes:
(a) 
Existing (predevelopment) non-forested pervious areas must be considered meadow in good condition.
(b) 
Twenty percent of existing impervious area, when present, shall be considered meadow in good condition in the model for existing conditions.
B. 
The Simplified Method (CG-2 in the BMP Manual, see § 252-45C) provided below is independent of site conditions and should be used if the Design Storm Method is not followed. This method is not applicable to regulated activities greater than one acre or for projects that require design of stormwater storage facilities. For new impervious surfaces:
(1) 
Stormwater facilities shall capture at least the first two inches of runoff from all new impervious surfaces.
(2) 
At least the first inch of runoff from new impervious surfaces 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.
(3) 
Wherever possible, infiltration facilities should be designed to accommodate infiltration of the entire permanently removed runoff; however, in all cases at least the first 0.5 inch of the permanently removed runoff should be infiltrated.
(4) 
This method is exempt from the requirements of § 252-13, Rate controls.
[Amended 9-26-2022 by Ord. No. 2022-4]
A. 
For computation of predevelopment peak discharge rates, 20% of the existing impervious area of a project site, when present, shall be considered meadow.
B. 
Postdevelopment discharge rates shall not exceed the predevelopment discharge rates for the one-, two-, five-, ten-, twenty-five-, fifty-, and one-hundred-year twenty-four-hour storms. If it is shown that the peak rates of discharge indicated by the postdevelopment analysis are less than or equal to the peak rates of discharge indicated by the predevelopment analysis for one-, two-, five-, 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.
C. 
For areas covered by a release rate map from an approved Act 167 Stormwater Management Plan:
For the one-, two-, five-, ten-, twenty-five-, fifty-, and 100-year, twenty-four-hour storm events, the post-development peak discharge rates will follow the applicable approved release rate maps. For any areas not shown on the release rate maps, the post-development discharge rates shall not exceed the pre-development discharge rates.
[Added 9-26-2022 by Ord. No. 2022-4]
A. 
In order to protect and improve water quality, a riparian buffer easement shall be created and recorded as part of any subdivision or land development that encompasses a riparian buffer.
B. 
Except as required by Chapter 102, the riparian buffer easement shall be measured to be the greater of the limit of the 100-year floodplain or a minimum of 35 feet from the top of the streambank (on each side).
C. 
Minimum management requirements for riparian buffers.
(1) 
Existing native vegetation shall be protected and maintained within the riparian buffer easement.
(2) 
Whenever practicable, invasive vegetation shall be actively removed, and the riparian buffer 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.
D. 
The riparian buffer easement shall be enforceable by the municipality and shall be recorded in the appropriate 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 the continued private ownership and shall count toward the minimum lot area required by Zoning, unless otherwise specified in the municipal Zoning Ordinance.
E. 
Any permitted use within the riparian buffer easement shall be conducted in a manner that will maintain the extent of the existing 100-year floodplain, improve or maintain the stream stability, and preserve and protect the ecological function of the floodplain.
F. 
Permitted uses. The following uses shall be permitted within the riparian buffer easement, provided that they are in compliance with the provisions of the underlying zoning district, are not prohibited by another Fairview Township ordinance or regulation.
(1) 
Common open space, nature preserves and wildlife sanctuaries, forest preserves, passive recreational and park areas, trails, greenways, and similar uses.
(2) 
Fishing, swimming, boating, etc.
(3) 
Boat launch facilities, provided that parking areas and other uses associated with the boat launch are placed outside of the riparian buffer easement.
(4) 
River-oriented uses.
(5) 
Municipal-owned uses.
(6) 
Educational and scientific uses.
(7) 
Essential services.
(8) 
Stream bank and watershed improvements approved by the York County Conservation District, and/or the Commonwealth of Pennsylvania.
(9) 
Crossings by recreational trails, roads, railroads, sewer and water lines, and public utility transmission lines, provided that all necessary permits and approvals from federal, state, and local agencies are received and that required plantings are of native species and maintained.
G. 
Prohibited uses. The following uses shall be prohibited in the riparian buffer easement.
(1) 
Grading, filling, or earthmoving which alters or changes the natural ridgelines and/or stream banks.
(2) 
Storage and/or disposal of any toxic, hazardous, or noxious substance.
(3) 
Storing of junk (residential and non-residential).
(4) 
Unenclosed storage.
(5) 
Septic drainfields and sewage disposal systems shall not be permitted within the riparian buffer easement and shall comply with setback requirements established under 25 Pa. Code Chapter 73.
H. 
Required vegetation. Within the riparian buffer easement, vegetative plantings including trees, shrubs and ground cover shall be provided and shall be maintained for stream bank stabilization, soil stability, and habitat for native animal species.
(1) 
Existing vegetative plantings shall not be removed within the riparian buffer easement, except:
(a) 
When associated with the development of an access point for a trail or other similar corridor, the width of such access point shall not exceed 12 feet in width.
(b) 
The removal of dead, diseased or damaged vegetation.
(c) 
The removal of invasive species and replacement with native species.
(d) 
Any new vegetative plantings and/or replacement of existing vegetative plantings shall be of native plant materials to stabilize any disturbed landscapes, improve the function of the floodplain, screen and buffer adjacent land uses and improve the aesthetic condition of the condition of the easement whenever possible.
(e) 
Regular maintenance/pruning of landscaping, including the removal of dead and/or diseased vegetation, shall be permitted.
I. 
The following conditions shall apply when public and/or private recreation trails are permitted within riparian buffers:
(1) 
Trails shall be for non-motorized use only.
(2) 
Trails shall be designed to have the least impact on native plant species and other sensitive environmental features.
(3) 
Trails shall be located a minimum 15 feet from the top of bank or edge of the watercourse.
A. 
For the purposes of the Act 167 Stormwater Management (Plan) elements contained within the York County Integrated Water Resources Plan, and this chapter, design policy pertaining to stormwater management facilities for Pennsylvania Department of Transportation (PennDOT) and Pennsylvania Turnpike Commission (PTC) roadways and associated facilities is provided in Section 13.7 (Antidegradation and Post Construction Stormwater Management Policy) of PennDOT Publication No. 13M, Design Manual Part 2 (August 2009), as developed, updated, and amended in consultation with the Pennsylvania Department of Environmental Protection (DEP). As stated in DM-2.13.7.D (Act 167 and Municipal Ordinances), PennDOT and PTC roadways and associated facilities shall be consistent with Act 167 Plans. DM-2.13.7.B (Policy on Antidegradation and Post-Construction Stormwater Management) was developed as a cooperative effort between PennDOT and DEP. DM-2.13.7.C (Project Categories) discusses the anticipated impact on the quality, volume, and rate of stormwater runoff.
B. 
Where standards in the Act 167 elements of the IWRP and this chapter are impractical, PennDOT or the PTC may request assistance from DEP, in consultation with the County, to develop an alternative strategy for meeting state water quality requirements and the goals and objectives of the Act 167 elements within the IWRP.
C. 
For the purposes of the Act 167 elements in the IWRP and this chapter, road maintenance activities are regulated under 25 Pa. Code Chapter 102.
A. 
Off-site areas. Off-site areas which drain through a proposed development site are not subject to release rate criteria when determining allowable peak runoff rates. However, on-site drainage facilities shall be designed to safely convey off-site flows through the development site.
B. 
On-site areas. On-site areas proposed to remain undisturbed as part of the regulated activity, including previously developed areas, that are not within the drainage area of any proposed BMPs shall be considered as existing conditions, without considering any reductions in cover type.
C. 
Downstream hydraulic capacity analysis. Any existing downstream hydraulic capacity analysis shall be conducted in accordance with this chapter.
(1) 
All downstream facilities impacted by the total site area of the regulated activity shall be studied to determine if the facility has adequate capacity to handle existing and proposed flows. An impacted downstream facility is one to which the runoff from the total site area of the regulated activity comprises more than 50% of the total flow to such a facility. The study shall end at a perennial stream. Downstream facilities include, but are not limited to, man-made or natural swales and open channels, pipes, inlets, culverts, bridges and roadways.
(2) 
If any private facility is found to be undersized, the applicant shall be responsible for updating the facility in coordination with the regulated activity.
(3) 
If any public facility is found to be undersized or inadequate, the applicant shall work with the Township on upgrading the facility in coordination with the regulated activity.
D. 
Regional detention alternatives. For certain areas within the study area, it may be more cost-effective to provide one control facility for more than one development site than to provide an individual control facility for each development site. The initiative and funding for any regional runoff control alternatives are the responsibility of prospective developers. The design of any regional control basins must incorporate reasonable development of the entire upstream watershed. The peak outflow of a regional basin would be determined on a case-by-case basis using the hydrologic model of the watershed consistent with protection of the downstream watershed areas. "Hydrologic model" refers to the calibrated model as developed for the stormwater management plan.
E. 
Capacity improvements of local drainage networks. In certain instances, local drainage conditions may dictate more stringent levels of runoff control than those based upon protection of the entire watershed. In these instances, if the developer could prove that it would be feasible to provide capacity improvements to relieve the capacity deficiency in the local drainage network, then the capacity improvements could be provided by the developer in lieu of runoff controls on the development site. Any capacity improvements would be designed based upon development of all areas tributary to the proposed improvement and the capacity criteria specified in § 252-17. In addition, all new development upstream of a proposed capacity improvement shall be assumed to implement the applicable runoff controls consistent with this chapter, except that all new development within the entire subarea(s) within which the proposed development site is located shall be assumed to implement the developer's proposed discharge control, if any.
F. 
Capacity improvements may also be provided as necessary to implement any regional or subregional detention alternatives.
G. 
Where the potential for groundwater and/or surface water contamination exists, based on the proposed use of the regulated activity, safeguards shall be incorporated into the site:
(1) 
For industrial or commercial sites where it is possible that toxic or hazardous substances may come into contact with stormwater runoff, pretreatment of the first-flush (first 1/2 inch) runoff over areas where industrial and commercial operations take place shall be provided. Pretreatment shall include means for separating light and heavy toxic and hazardous substances from the stormwater before the stormwater is conveyed to the general stormwater management facility(ies).
(2) 
Infiltration systems may be used to handle runoff from commercial or industrial working or parking areas only after the first-flush stormwater from these areas has been pretreated for removal of toxic and hazardous substances.
H. 
Roof drains and sump pumps shall discharge to infiltration or vegetative BMPs and to the maximum extent practicable satisfy the criteria for DIAs.
A. 
Any stormwater facility located on state highway rights-of-way shall be subject to approval by the Pennsylvania Department of Transportation (PennDOT).
B. 
Any stormwater management facilities regulated by this chapter that would be located in or adjacent to waters of the commonwealth or wetlands shall be subject to approval by PA DEP through the joint permit application process, or, where deemed appropriate by PA DEP, the general permit process. When there is a question whether wetlands may be involved, it is the responsibility of the developer or his agent to show that the land in question cannot be classified as wetlands; otherwise, approval to work in the area must be obtained from PA DEP.
C. 
Any stormwater management facility located within the vicinity of a floodplain shall be subject to approval in accordance with PA DEP 25 Pa. Code Chapter 106 (Floodplain Management) of PA DEP's Rules and Regulations.
D. 
All earthmoving activities must be reviewed and approved by the York County Conservation District prior to commencing work.
E. 
The design of all stormwater management facilities shall incorporate good engineering principles and practices. The Township shall reserve the right to disapprove any design that would result in the occupancy or continuation of adverse hydrologic or hydraulic conditions within the watershed.
F. 
The existing points of concentrated drainage that discharge onto adjacent property shall not be altered without permission of the adjacent property owner(s) and shall be subject to any applicable discharge criteria specified in this chapter.
G. 
Areas of existing diffused drainage discharge shall be subject to any applicable discharge criteria in the general direction of existing discharge, whether proposed to be concentrated or maintained as diffused drainage areas, except as otherwise provided by this chapter. If diffused flow is proposed to be concentrated and discharged onto adjacent property, the developer must document that adequate downstream conveyance facilities exist to safely transport the concentrated discharge, or otherwise prove that no erosion, sedimentation, flooding or other harm will result from the concentrated discharge.
H. 
Where a development site is traversed by watercourses, drainage easements shall be provided conforming to the line of such watercourses. The terms of the easement shall prohibit excavation, the placing of fill or structures, and any alterations that may adversely affect the flow of stormwater within any portion of the easement. Also, maintaining of vegetation in a natural state within the easement shall be required, except as approved by the appropriate governing authority.
I. 
When it can be shown that, due to topographic conditions, natural drainageways on the site cannot adequately provide for drainage, open channels may be constructed conforming substantially to the line and grade of such natural drainageways. Work within natural drainage ways shall be subject to approval by PA DEP through the joint permit application process, or, where deemed appropriate by PA DEP, through the General Permit process.
J. 
Roof drains must not be connected to streets, sanitary or storm sewers or roadside ditches to promote overland flow and infiltration/percolation of stormwater where advantageous to do so. When it is more advantageous to connect directly to streets or storm sewers, then it shall be permitted on a case-by-case basis by the Township.
K. 
Special requirements for areas falling within defined exceptional value and high-quality subwatersheds. The temperature and quality of water and streams that have been declared as exceptional value and high quality is to be maintained as defined in Chapter 93, Water Quality Standards, Title 25 of Pennsylvania Department of Environmental Protection Rules and Regulations. Temperature-sensitive BMPs and stormwater conveyance systems are to be used and designed with storage pool areas and supply outflow channels and should be shaded with trees. This will require modification of berms for permanent ponds and the relaxation of restrictions on planting vegetation within the facilities, provided that capacity for volumes and rate control is maintained. At a minimum, the southern half on pond shorelines shall be planted with shade or canopy trees within 10 feet of the pond shoreline. In conjunction with this requirement, the maximum slope allowed on the berm area to be planted is 10 to 1. This will lessen the destabilization of berm soils due to root growth. A long-term maintenance schedule and management plan for the thermal control BMPs is to be established and recorded for all development sites within defined exceptional value and/or high-quality subwatersheds.
[Amended 1-25-2016 by Ord. No. 2016-1; 9-26-2022 by Ord. No. 2022-4]
A. 
Stormwater runoff from all development sites shall be calculated using the Rational Method, Modified Rational Method, or a Soil Cover Complex methodology.
(1) 
Any stormwater runoff calculations involving drainage areas greater than 200 acres, including on- and off-site areas, shall use generally accepted calculation technique that is based on the NRCS Soil Cover Complex method. 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 site.
(2) 
The Township may allow the use of the Rational Method or Modified Rational Method to estimate peak discharges from drainage areas that contain less than 200 acres. Use NRES when NPDES permit is required.
(3) 
All calculations consistent with this chapter using the Soil Cover Complex method shall use the appropriate design rainfall depths. If a hydrologic computer model such as PSRM or HEC-RAS is used for stormwater runoff calculations, then the duration of rainfall shall be 24 hours. The NRCS Rainfall Type II curve shall be used for the rainfall distribution.
(4) 
For the purposes of predevelopment flow rate determination, undeveloped land, including areas to be disturbed as part of the regulated activity, shall be considered as "meadow" in good condition, unless the natural ground cover generates a lower curve number or Rational "C" value (i.e., forest), as listed in Tables 1 and 2, respectively.[1]
[1]
Editor's Note: Tables 1 and 2 are included as attachments to this chapter.
(5) 
All calculations using the Rational Method shall use rainfall intensities consistent with appropriate times-of-concentration for overland flow and return periods. Times-of-concentration for overland flow shall be calculated using the methodology presented in Chapter 3 of Urban Hydrology for Small Watersheds, NRCS, TR-55 (as amended or replaced from time to time by NRCS). Time-of-concentration for channel and pipe flow shall be computed using Manning's equation.
(6) 
Runoff Curve Numbers (CN) for both existing and proposed conditions to be used in the Soil Cover Complex method shall be obtained from Table 1.
(7) 
Runoff coefficients (c) for both existing and proposed conditions for use in the Rational Method shall be obtained from Table 2.
(8) 
Where uniform flow is anticipated, the Manning equation shall be used for hydraulic computations such as the capacity of open channels, pipes, and storm sewers. Values for Manning's roughness coefficient (n) shall be consistent with Table 3.[2]
(9) 
The design of any stormwater detention facilities intended to meet the performance standards of this chapter shall be verified by routing the design storm hydrograph through these facilities, using either manual methods or computerized routing. Routing shall be based upon the modified PULS method; other routing methodologies shall be subject to the approval of the Township Engineer.
(10) 
The stormwater collection system shall be designed using the peak discharge computed using the Rational Formula.
B. 
Water carrying facilities:
(1) 
All storm sewer pipes, grass waterways, open channels, swales, and other water-carrying facilities that service drainage areas within the site shall be designed to convey the twenty-five-year storm event unless in the opinion of the Township or Township Engineer the character of development and potential for damage warrant design for the fifty- or 100-year storm.
(2) 
Storm water management facilities that convey off-site water through the site shall be designed to convey the fifty-year storm event.
(3) 
All developments shall include provisions that allow for the overland conveyance and flow of the post-developed 100-year storm event without damage to public or private property.
(4) 
A 100-year storm frequency may be required for design of the stormwater collection system to ensure that the resultant stormwater runoff from the post-development storm is directed into the management facility.
(5) 
Conveyance facilities shall comply with the design criteria in the following table:
Conveyance Facility Design Criteria
Location
Within Public Street Right-of-Way/Paved Areas
Outside Public Street Right-of-Way
a) Pipe Design
1. Material
SLHDPE/RCP
SLHDPE/RCP
2. Slope (minimum)
0.50%
0.50%
3. Cover
1' to stone subgrade
1' to surface
4. Diameter (minimum)
18 inches
Per design calculations
5. Street crossing angle
90°
N/A
6. Access/maintenance port frequency (maximum)
400 feet
400 feet
b) Inlet Design
1. Material
Concrete
Concrete
2. Grate depression
N/A
6 inches
c) Manhole Design
1. Material
Concrete
Concrete
d) Swale Design
1. Freeboard (minimum)
6 inches
6 inches
2. Velocity (maximum)
Stability check
Stability check
3. Slope (minimum)
2%
1%
4. Side Slopes
3:1 max
3:1 max
5. Bottom width to flow depth ratio
12:01
12:01
e) Pipe Inlet/Outlet Design
1. End treatment
Concrete headwall/endwall
Concrete headwall/endwall
2. Energy dissipator
Required
Required
(6) 
Storm sewer pipes, culverts, manholes, inlets, endwalls, and end sections proposed for dedication or located along streets shall conform to the requirements of the Pennsylvania Department of Transportation, Bureau of Design, Standards for Roadway Construction, Publication No. 72, in effect at the time the design is submitted.
(7) 
The roughness coefficient (Manning "n" values) used for conveyance pipe capacity calculations shall be determined in accordance with PennDOT Publication 584, PennDOT Drainage Manual, or per the manufacturer's specifications.
(8) 
Inlets shall be placed along streets as follows:
(a) 
On both sides of streets at low spots. All inlets at low points along the roadway shall have a ten-inch curb reveal and shall be equipped with pavement base drain extending 50 feet in either direction, parallel to the center line of the roadway.
(b) 
At all changes in the horizontal or vertical direction of storm sewers.
(c) 
Stormwater runoff on roadways (i.e., gutter spread, lane encroachment, etc.) shall be controlled in accordance with PennDOT Publications 13M, "Design Manual, Part 2" and 584, "Drainage Manual."
(d) 
At or beyond the curb radius points at intersections.
[1] 
For the purpose of inlet location at intersections, the depth of flow shall be considered for each gutter.
[2] 
At intersections, the depth of flow for the twenty-five-year storm across the through streets shall not exceed one inch.
(9) 
Inlets shall be depressed below the grade of the road-side swale or ground surface as indicated in the above design chart.
(10) 
An access/maintenance port may either be an inlet or manhole.
(11) 
Manholes may be substituted for inlets at locations where inlets are not required to collect surface runoff.
(12) 
Material consistency and placement depths for storm sewer pipe 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) stone, rock, or other objectionable or detritus material.
(13) 
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.
(14) 
All inlets placed in paved areas shall have heavy duty bicycle-safe grating consistent with PennDOT Publication 72M, latest edition. A note to this effect shall be added to the stormwater management site plan or inlet details therein.
(15) 
Where the connecting pipe has a diameter 18 inches or greater, headwalls and endwalls shall be provided with a protective barrier device to prevent entry of the storm sewer pipe by unauthorized persons. Such protection devices shall be designed to be removable for cleaning.
(16) 
Flow velocities from any storm sewer shall not result in a degradation of the receiving channel.
(17) 
Energy dissipaters shall be placed at the outlets of all storm sewer pipes where flow velocities exceed maximum permitted channel velocities.
(18) 
Roadway crossings located within flood-prone areas, as defined by Chapter 151 of the Fairview Township Code, or as otherwise directed by the Township Engineer, must be able to safely convey runoff from the 100-year design storm with a minimum of one foot of freeboard measured below the lowest point along the top of the roadway. For bridges, freeboard shall be measured below the low chord elevation of the bridge.
(19) 
Drainage conveyance facilities to or exiting from stormwater management facilities (i.e., detention basins) shall be designed to convey the design flow to or from that structure.
(20) 
The capacities of swales shall be computed from the Manning Equation using the following design parameters: Permissible open channel velocities and design standards shall be in accordance with good engineering practice as documented in the Engineering Field Manual for Conservation Practices, U.S.D.A., S.C.S., or in Design Charts for Open-Channel Flow, Hydraulic Design Series No. 3, U.S. Department of Transportation.
(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] 
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 Township Engineer.
(b) 
All swales shall be designed to maximize infiltration and concentrate low flows to minimize siltation and meandering unless geotechnical conditions do not permit infiltration.
(c) 
All grass-lined swales shall be provided with a minimum of four inches of topsoil. Swales shall be mulched and seeded with Formula B seed mixture in areas that will be mowed and Formula D seed mixture in areas with limited access that will not be mowed, in accordance with the latest edition of PennDOT Publication 408, § 804, or its successor publications pertaining to the same subject matter.
C. 
Above ground storage facilities:
(1) 
Above ground storage facilities shall consist of all stormwater facilities which store, infiltrate/evaporate/transpire, clean, release, or otherwise affect stormwater runoff and the top of which is exposed to the natural environment. Above ground storage facilities shall be located above the finished ground elevation. Above ground storage facilities do not include stormwater management facilities designed for conveyance, or cisterns.
(2) 
Facilities with a facility depth greater than six feet shall not be permitted in residential areas. Facility depth shall be measured from the bottom of the emergency spillway to the lowest point in the facility.
(3) 
Above ground storage facilities shall comply with the design criteria in the following table:
Above Ground Storage Facility Design Criteria
Facility Depth
Less than 2 feet
2 feet to 6 feet
Greater than 6 feet
a. Embankment Geometry
1. Top width (minimum)
2 feet
6 feet
8 feet
2. Interior side slope (maximum)
3:1
4:1
4:1
3. Exterior side slope (maximum)
3:1
4:1
4:1
b. Embankment Construction
1. Clay/Impervious Core
Not required
Required
Required
2. Pipe collar
Not required
Required
Required
3. Compaction density
Not required
Required
Required
c. Internal Construction
1. Dewatering feature
N/A
Required
Required
2. Pretreatment elements
Not required*
Required
Required
d. Outlet Structure
1. Pipe size (minimum)
12 inches
18 inches
18 inches
2. Pipe material
SLHDPE, PVC, RCP
SLHDPE**, RCP
SLHDPE**, RCP
3. Anticlogging devices
Required
Required
Required
4. Antivortex design
Not required
Required
Required
5. Watertight joints in piping
Yes
Yes
Yes
e. Spillway Requirements
1. Spillway freeboard (minimum)
3 inches
6 inches
12 inches
2. Width (minimum)
5 feet
10 feet
20 feet
3. Width (maximum)
20 feet
50 feet
50 feet
4. Spillway channel design
Required
Required
Required
5. Routing of 100-year storm
Permitted
Permitted
Permitted
NOTES:
*
Pretreatment is required for infiltration BMPs unless shown to be unnecessary.
**
SLDPE pipe shall be provided with a concrete cradle extending through the basin embankment.
N/A = Not applicable
SLHDPE = Smooth lined high density polyethylene pipe; PVC = Polyvinyl chloride;
RCP = Reinforced concrete pipe
(4) 
If required, pretreatment elements shall be designed according to the BMP manual, see § 252-45C.
(5) 
All above ground storage facilities shall be structurally sound and shall be constructed of sound and durable materials.
(a) 
All discharge control devices with appurtenances shall be made of reinforced concrete and stainless steel.
(b) 
Bolts/fasteners shall be stainless steel.
(c) 
The completed structure and the foundation of all basins shall be stable under all probable conditions of operation.
(d) 
Spillways shall be capable of discharging the peak discharge of a post-development 100-year storm event through the emergency spillway facilities, in a condition that assumes the primary outlet(s) are blocked, which will not damage the integrity of the facility or the downstream drainage areas.
(e) 
Use of the spillway to convey flows greater than the fifty-year design storm shall be permitted.
(f) 
The effect on downstream areas if the above ground storage facility embankment fails shall be considered in the design of all basins. The basin shall be designed to minimize the potential damage caused by such failure of the embankment.
(g) 
An easement shall be provided from the spillway outfall to a natural or artificial watercourse.
(6) 
All detention basins shall include an outlet structure to permit draining the Rate Control Volume within 24 hours, exclusive of BMP storage.
(7) 
All outlet structures and emergency spillways shall include a satisfactory means of dissipating the energy of flow at its outlet to assure conveyance of flow without endangering the safety and integrity of the basin and the downstream drainage area. Discharges from piping outlets of stormwater management facilities shall be provided with a concrete "level spreader" to convert point discharge back to simulated sheet flow. The length of the spreader shall be equal to 10 times the outlet pipe diameter (e.g., an eighteen-inch discharge pipe would require a fifteen-foot-wide level spreader).
(8) 
A concentrated discharge of stormwater to an adjacent property shall be within a natural drainageway or watercourse, or an easement shall be required.
(9) 
Easement. SWM site plans showing outlet control structures shall contain an easement dedication as follows: "An easement is hereby granted to Fairview Township to access and modify the basin outlet control device at the expense of the developer so as to function within design parameters."
(10) 
Plans for infiltration must show the locations of existing and proposed septic tank infiltration areas and wells. A minimum twenty-five-foot separation from on-lot disposal system (OLDS) infiltration areas, including replacement areas, is required. Infiltration rates shall be based upon perc and probe tests conducted at the site of the proposed facility.
(11) 
Where a basin embankment is constructed using fill on an existing 15% or greater slope, the basin must be keyed into the existing grade.
(12) 
A clay/impervious core shall consist of a cutoff trench (below existing grade) and a core trench (above existing grade).
(a) 
A clay/impervious core may not be required wherever the facility depth is less than two feet.
(b) 
Materials used for the clay/impervious core shall conform to the Unified Soil Classification GC, SC, CH, or CL and must have at least 30% passing the No. 200 sieve.
(c) 
The dimensions of the clay/impervious core shall provide a minimum trench depth of two feet below existing grade, minimum width of four feet and side slope of 1H:1V or flatter.
(d) 
The clay/impervious core should extend up to the twenty-five-year water surface elevation or six inches below the emergency spillway elevation, whichever is lower.
(e) 
The clay/impervious core shall extend four feet below any pipe penetrations through the impervious core.
(f) 
The core shall be installed along or parallel to the centerline of the embankment.
(g) 
Compaction requirements for the clay/impervious core shall be the same as those for the embankment to assure maximum density and minimum permeability.
(13) 
All pipe collars, if required, shall be designed in accordance with Chapter 7 of the PA DEP Erosion and Sediment Control Manual. The material shall consist of concrete or otherwise non-degradable material around the outfall barrel and shall be watertight.
(14) 
The embankment fill material shall be free of topsoil, organic material, roots, stumps, wood, rubbish, stones greater than six inches, frozen or other objectionable materials.
(15) 
The minimum freeboard for spillways shall be provided above the 100-year design elevation of the water surface at the emergency spillway in a condition that assumes the primary outlet(s) is (are) blocked.
(16) 
The minimum bottom slope of facilities not designed for infiltration shall be 2%. A flatter slope may be used if an equivalent dewatering mechanism is provided.
(17) 
If required, dewatering shall be provided through the use of underdrain, surface device, or an alternate approved by the Township Engineer. If the facility is to be used for infiltration, the dewatering device should be capable of being disconnected and only be made operational if the basin is not dewatering within the required timeframe.
(18) 
Within basins designed for infiltration, a planting plan shall be prepared in accordance with this Ordinance and the BMP Manual, see § 252-45C.
(19) 
Lots adjacent to basins shall have a lowest floor elevation at least 1 1/2 feet higher than the 100-year water surface elevation in the basin.
(20) 
All stormwater runoff storage facilities must be located outside of flood prone areas, as defined by Chapter 151 of the Fairview Township Code.
(21) 
Access. All stormwater management facilities shall be accessible by vehicular means along stabilized access roads in order to allow for proper maintenance as required.
(22) 
Fencing. Any aboveground stormwater management detention/retention facility that is designed to store at least a two-foot depth of runoff, or where determined necessary by the Township Engineer, shall be subject to the following fencing requirements:
(a) 
Stormwater facility must be completely surrounded by a chain-link fence of not less than four feet in height. Alternative fences and barriers may be permitted upon request to and approval by the Township.
(b) 
All gates or doors opening through such enclosure shall be equipped with a latching device for keeping the gate or door securely closed at all times, when not in actual use.
(23) 
Where required, impermeable liner shall be constructed to meet the following minimum requirements:
(a) 
The minimum liner required is 30-mil high density polyethene (HDPE) and must be UV resistant. Actual individual liner specifications shall be provided by the manufacturer for each individual pond.
(b) 
The liner must be placed on a layer of fine-grained soil that has been rolled with a smooth drum roller in both directions to produce a smooth level base for the liner. The soil may not contain sharp angular rock or other debris that could puncture the liner and must meet all manufacturers' specifications for a liner bedding. All vegetation, roots, and grass must be removed, and any cracks or voids shall be filled.
(c) 
If rock is encountered in the bedding area, this rock must be excavated to a depth of six inches below the liner and backfilled with a fine-grained soil. This area should then be covered with geotextile fabric, extending three feet beyond the limits of the rock outcrop before placing the pond liner.
(d) 
Installation of the liner may only take place when the ambient temperature is within the manufacturer's specifications. The number of field seams shall be minimized by requiring factory fabrication of large panels. Any field seams performed must be in accordance with the manufacturer's specifications.
(e) 
All structures (i.e., headwalls, pipes, outlet structures) which come in contact with the liner must have a waterproof seal installed to prevent leaks around the structure. These seals shall be installed per manufacturer's recommendations.
(f) 
A minimum of 12 inches of earth cover shall be placed over the lining. Soil containing sharp jagged rocks, roots, debris, or any other material that may puncture the liner shall not be used as cover material.
(g) 
The liner must be installed to a minimum height of the 100-year flood water elevation in the facility.
D. 
Subsurface storage facilities:
(1) 
Subsurface storage facilities shall consist of all stormwater facilities which store, infiltrate/evaporate/transpire, clean, release, or otherwise affect stormwater runoff and the top of which is not exposed to the natural environment. Subsurface facilities shall be located below the finished ground elevation. Subsurface facilities shall not include stormwater management facilities designed for conveyance.
(2) 
Subsurface storage facilities shall comply with the design criteria in the following table:
Subsurface Storage Facility Design Criteria
Facility Type
Infiltration and Storage
Storage without Infiltration
a. Facility Geometry
1. Depth from surface (maximum)
2 feet less than limiting zone
N/A
2. Loading ratio (maximum)
Per BMP Manual (see § 252-45C)*
N/A
b. Distribution System Requirements
1. Pipe size (minimum)
4 inches
4 inches
2. Loading/balancing
Required
Required
3. Observation/access ports
Required
Required
NOTES:
*
Unless otherwise determined by professional geologic evaluation.
(3) 
The facility shall be designed according to the BMP Manual, see § 252-45C, to provide pretreatment to eliminate solids, sediment, and other debris from entering the subsurface facility.
(4) 
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.
(5) 
Observation/access ports shall be provided for all subsurface storage facilities as follows:
(a) 
For facilities with the bottom less than five feet below the average grade of the ground surface, a clean-out shall be an acceptable observation port.
(b) 
For facilities with the bottom five feet or more below the average grade of the ground surface, a manhole or other means acceptable to the Township shall be provided for access to and monitoring of the facility.
(c) 
The number of access points shall be sufficient to flush or clean out the system.
(6) 
Storage and distribution system piping shall be PVC, SLHDPE, or RCP.
(7) 
The stone used for infiltration beds shall be clean washed, uniformly graded coarse aggregate. The void ratio for design shall be assumed to be 40%.
(8) 
Material consistency and placement depths for backfill shall be (at a minimum) per all applicable pipe manufacturer's recommendations.
(a) 
Backfill material shall be free of large (not exceeding six inches in any dimension) stone, rock, or other objectionable or detritus material.
(b) 
Select non-aggregate backfill material should be indigenous to the surrounding soil material for non-vehicular areas.
(c) 
Backfill material within vehicular areas shall comply with the requirements of the governing municipal road/street or subdivision and land development ordinance.
(d) 
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.
(9) 
Non-woven geotextiles shall be placed on the sides and top of subsurface infiltration facilities.
(10) 
When located under pavement, the top of the subsurface facility shall be a minimum of three inches below the bottom of 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.
(11) 
Subsurface facilities shall be designed to safely convey and/or bypass flows from storms exceeding the design storm.
A. 
In areas of carbonate geology, a geologist shall certify to the following:
(1) 
No stormwater management facility will be placed in, over, or immediately adjacent to the following features:
(a) 
Closer than 100 feet from sinkholes.
(b) 
Closer than 100 feet from closed depressions.
(c) 
Closer than 100 feet from caverns, intermittent lakes, or ephemeral streams.
(d) 
Closer than 50 feet from lineaments in carbonate areas.
(e) 
Closer than 50 feet from fracture traces.
(f) 
Closer than 25 feet from bedrock pinnacles (surface or subsurface).
(2) 
Stormwater resulting from regulated activities shall not be discharged into sinkholes.
(3) 
If the developer can prove through analysis that the project site is an area underlain by carbonate geology, and such geologic conditions may result in sinkhole formations, then the project site is exempt from recharge requirements as described in § 252-12, Volume control. However, the project site shall still be required to meet all other standards found in this chapter.
(4) 
It shall be the developer's responsibility to verify if the project site is underlain by carbonate geology to the satisfaction of the Township Engineer. The following note shall be attached to all stormwater management plans and signed and sealed by the developer's geologist: "I, _____________________, certify that the proposed stormwater management facility (circle one) is/is not underlain by carbonate geology."
(5) 
Whenever a stormwater management facility will be located in an area underlain by carbonate geology, a geological evaluation of the proposed location by a geologist shall be conducted to determine susceptibility to sinkhole formation, or if carbonate geology is known to the Township or its engineers or consultants. The evaluation may include the use of impermeable liners to reduce or eliminate the separation distances listed in the BMP Manual. Additionally, the evaluation shall, at a minimum, address soil permeability, depth to bedrock, seasonally high groundwater table, susceptibility for sinkhole formation, suitability of stormwater management facilities, subgrade stability and maximum infiltration capacity in depth of water per unit area.
(6) 
A detailed soils evaluation of the project site shall be performed to determine the suitability of recharge facilities. The evaluation shall be performed by a qualified professional, and at a minimum, address soil permeability, depth to bedrock, susceptibility to sinkhole formation, and subgrade stability. The general process for designing the infiltration BMP shall be:
(a) 
Site evaluation to determine general areas of suitability for infiltration practices.
(b) 
Provide field test throughout the area proposed for development to determine appropriate percolation rate and/or hydraulic conductivity. At least one infiltration test must be included in each soil group and at least one infiltration test must be conducted for each five lots proposed for development. Infiltration tests must be taken at the location and depth of all proposed infiltration structures.
(c) 
Design infiltration structure for required storm volume based on all available data.
(7) 
Extreme caution shall be exercised where infiltration is proposed in geologically susceptible areas such as strip mine or limestone areas. It is also extremely important that the design professional evaluate the possibility of groundwater contamination from the proposed infiltration/recharge facility and recommend a hydrogeologic justification study be performed if necessary. Whenever a basin will be located in an area underlain by limestone, a geological evaluation of the proposed location shall be conducted to determine susceptibility to sinkhole formations. The design of all facilities over carbonate formations shall include measures to prevent groundwater contamination and, where necessary, sinkhole formation. The infiltration requirement in the high-quality/exceptional waters shall be subject to the Department's Chapter 93 and antidegradation regulations. A detailed hydrogeologic investigation may be required by the Township and, where appropriate, the Township may require the installation of an impermeable liner in detention basins.
A. 
As required in § 252-10D, whenever the vegetation and topography are to be disturbed, such activity must be in conformance with PA DEP 25 Pa. Code Chapter 105, Rules and Regulations, Part I, Subpart C, Protection of Natural Resources, Article II, Water Resources, Chapter 102, "Erosion Control," and in accordance with the York County Conservation District.
B. 
It is extremely important that strict erosion and sedimentation control measures be applied surrounding infiltration structures during installation to prevent the infiltrative surfaces from becoming clogged. Additional erosion and sedimentation control design standards and criteria must be applied where infiltration BMPs are proposed shall include the following:
(1) 
Areas proposed for infiltration BMPs shall be protected from sedimentation and compaction during the construction phase, so as to maintain their maximum infiltration capacity.
C. 
Fencing for sedimentation basins or traps must comply with § 252-17C(1)(j).
D. 
The developer shall demonstrate that the postdevelopment hydrograph flows during erosion and sedimentation control phase are less than or equal to the predevelopment hydrograph flows to assure the rate and volume of runoff leaving the site is controlled for the two-, five-, and ten-year frequency storms. All calculation methodology shall be in accordance with §§ 252-12 through 252-19.