Township of Lower Saucon, PA Article III Stormwater Management

§ 137-11 General requirements.

A. All regulated activities in the Township shall be subject to the stormwater management requirements of this chapter.

B. Storm drainage systems shall be provided to permit unobstructed flow in natural watercourses except as modified by stormwater detention facilities, recharge facilities, water quality facilities, pipe systems or open channels consistent with this chapter.

C. The existing locations of concentrated drainage discharge onto adjacent property shall not be altered without prior written approval of the affected property owner(s).

D. Areas of existing diffused drainage discharge onto adjacent property shall be managed such that, at minimum, the peak diffused flow does not increase in the general direction of discharge, except as otherwise provided in this chapter. If diffused flow is proposed to be concentrated and discharged onto adjacent property, the developer must document that there are adequate downstream conveyance facilities to safely transport the concentrated discharge to the point of predevelopment flow concentration, to the stream reach or otherwise prove that no harm will result from the concentrated discharge. Areas of existing diffused drainage discharge shall be subject to any applicable release rate criteria in the general direction of existing discharge, whether they are proposed to be concentrated or maintained as diffused drainage areas.

E. Where a site is traversed by watercourses other than those for which a 100-year floodplain is defined by the Township, there shall be provided drainage easements conforming substantially with the line of such watercourses. The width of any easement shall be adequate to provide for unimpeded flow of storm runoff based on calculations made in conformance with § 137-14 of this chapter for the 100-year return period runoff and to provide a freeboard allowance of 0.5 foot above the design water surface level. The terms of the easement shall prohibit excavation, the placing of fill or structures, and any alterations which may adversely affect the flow of stormwater within any portion of the easement. Also, periodic maintenance of the easement to ensure proper runoff conveyance shall be required. Watercourses for which the 100-year floodplain is formally defined are subject to the applicable Township floodplain regulations.

F. Post-construction BMPs shall be designed, installed, operated and maintained to meet the requirements of the Clean Streams Law[1] and implementing regulations, including the established practices in 25 Pa. Code Chapter 102 and the specifications of this chapter.

[1] Editor's Note: See 35 P.S. § 691.1 et seq.

G. No earth disturbance activities associated with any regulated activities shall commence until approval by the Township of a plan which demonstrates compliance with the requirements of this chapter.

H. Techniques described in Appendix F (Low-Impact Development) of this chapter[2] are encouraged because they reduce the costs of complying with the requirements of this chapter and the commonwealth water quality requirements.

[2] Editor's Note: Appendix F is included as an attachment to this chapter.

I. Infiltration for stormwater management is encouraged where soils and geology permit, consistent with the provisions of this chapter and, where appropriate, the Recommendation Chart for Infiltration Stormwater Management BMPs in Carbonate Bedrock in Appendix D of this chapter.[3]

[3] Editor's Note: Appendix D is included as an attachment to this chapter.

§ 137-12 Stormwater management districts.

A. To implement the provisions of the several DEP-approved Act 167 stormwater management plans that include areas of the Township, the Township is hereby divided into stormwater management districts consistent with the release rate maps presented in the plans. The boundaries of the stormwater management districts are shown on official maps which are available for inspection at the Township office. Any areas of the Township which are outside of a DEP-approved stormwater management plan area are subject to 100% release rate criteria.

B. Description of stormwater management districts not within the Delaware River (North) Watershed. In all stormwater management districts not within the Delaware River North Watershed, the two-year post-development peak discharge must be controlled to 30% of the predevelopment two-year runoff peak. Two types of stormwater management districts are applicable, namely Conditional/Provisional No Detention Districts and Dual Release Rate Districts, which are further regulated as described below.

(1) Conditional/Provisional No Detention Districts. Within these districts, the capacity of the local runoff conveyance facilities (as defined in Article II) must be calculated to determine if adequate capacity exists. For this determination, the developer must calculate peak flows assuming that the site is developed as proposed and that the remainder of the local watershed is in the existing condition. The developer must also calculate peak flows assuming that the entire local watershed is developed per current zoning and that all new development would use the runoff controls specified by this chapter. The larger of the two peak flows calculated will be used in determining if adequate capacity exists. If the site is found unsuitable for infiltration (and only to the extent that it is found unsuitable) per § 137-17 and adequate capacity exists to safely transport runoff from the site to the main channel (as defined in Article II), these watershed areas may discharge post-development peak runoff without peak rate control for any storms greater than the two-year storm. If the capacity calculations show that the local runoff conveyance facilities lack adequate capacity, the developer shall either use a 100% release rate control or provide increased capacity of downstream elements to convey increased peak flows consistent with § 137-13N. Any capacity improvements must be designed to convey runoff from development of all areas tributary to the improvement consistent with the capacity criteria specified in § 137-13D. By definition, a storm drainage problem area associated with the local runoff conveyance facilities indicates that adequate capacity does not exist. Sites in these districts are still required to meet all of the water quality requirements of this chapter.

(2) Dual release rate districts. Within these districts, the ten-, twenty-five-, and 100-year post-development peak runoff must be controlled to the stated percentage of the predevelopment peak. Release rates associated with the ten- through 100-year events vary from 50% to 100%, depending upon location in the watershed.

C. Description of stormwater management districts within the Delaware River (North) Watershed. Two types of stormwater management districts are applicable to the areas of the Township within this watershed. These are the 100% Release Rate District and the 75% Release Rate District as described below.

(1) One hundred percent release rate districts. These subareas are not expected to incur a great deal of development growth due to location, topography, soils or a combination of all three factors. Also, the location in the watershed of these subareas is of minor importance in supporting the overall watershed level runoff control. Therefore, these areas are allowed to release development runoff at a rate that does not exceed the existing rates of runoff.

(2) Seventy five percent release rate districts. Certain subareas require the control of stormwater runoff to a portion of the existing runoff equal to 75%. These areas are located in upper reaches of the watershed. In order to ensure uniform watershed-level runoff control, the assignment of this release rate on a widespread basis will uniformly restrict the future runoff in a fashion that favors no particular subwatershed.

§ 137-13 Stormwater management district implementation.

A. Applicants shall provide a comparative pre- and post-construction stormwater management hydrograph analysis for each direction of discharge and for the site overall to demonstrate compliance with the provisions of this chapter.

B. Any stormwater management controls required by this chapter and subject to a dual release rate criteria shall meet the applicable release rate criteria for each of the two-, ten-, twenty-five-, and 100-year return period runoff events consistent with the calculation methodology specified in § 137-14 of this chapter.

C. The exact location of the stormwater management district boundaries as they apply to a given development site shall be determined by mapping the boundaries using the two-foot topographic contours provided as part of the drainage plan. The district boundaries as originally drawn coincide with topographic divides or, in certain instances, are drawn from the intersection of the watercourse and a physical feature, such as the confluence with another watercourse or a potential flow obstruction (e.g., road, culvert, bridge, etc.). The physical feature is the downstream limit of the subarea, and the subarea boundary is drawn from that point up slope to each topographic divide along the path perpendicular to the contour lines.

D. Any downstream capacity analysis conducted in accordance with this chapter shall use the greater of § 137-19E or the following criteria for determining adequacy for accepting increased peak flow rates:

(1) Natural or man-made channels or swales must be able to convey the increased runoff associated with a two-year return period event within their banks at velocities consistent with protection of the channels from erosion.

(2) Natural or man-made channels or swales must be able to convey the increased twenty-five-year return period runoff without creating any hazard to persons or property.

(3) Culverts, bridges, storm sewers or any other facilities which must pass or convey flows from the tributary area must be designed in accordance with the Pennsylvania Department of Environmental Protection (DEP) Chapter 105[1] regulations (if applicable) and, at minimum, pass the increased twenty-five-year return period runoff.

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

E. For a proposed development site located within one release rate category subarea, the total runoff from the site shall meet the applicable release rate criteria. For development sites with multiple directions of runoff discharge, individual drainage directions may be designed for up to a 100% release rate so long as the total runoff from the site is controlled to the applicable release rate.

F. For a proposed development site located within two or more release category subareas, the peak discharge rate from any subarea shall be the predevelopment peak discharge for that subarea multiplied by the applicable release rate. The calculated peak discharges shall apply regardless of whether the grading plan changes the drainage area by subarea. An exception to the above may be granted if discharges from multiple subareas recombine in proximity to the site. In this case, peak discharge in any direction may be a 100% release rate, provided that the overall site discharge meets the weighted average release rate.

G. For sites straddling major watershed divides (e.g., Monocacy Creek and Bushkill Creek), runoff volumes shall be managed to prevent diversion of runoff between watersheds, as practicable.

H. Within a release rate category area, for a proposed development site which has areas which drain to a closed depression(s), the design release from the site will be the lesser of a) the applicable release rate flow assuming no closed depression(s) or b) the existing peak flow actually leaving the site. In cases where b) would result in an unreasonably small design release, the design discharge of less than or equal to the release rate will be determined by the available downstream conveyance capacity to the main channel calculated using § 137-13D of this chapter and the minimum orifice criteria.

I. 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 using the capacity criteria in Chapter § 137-13D of this chapter and the detention criteria in this chapter. In addition to the criteria in Chapter § 137-13D of this chapter, on-site conveyance systems designed to carry runoff to a detention basin must be able to transport the basin's 100-year tributary flow either in-system, in-gutter or overland.

J. For development sites proposed to take place in phases, all detention ponds shall be designed to meet the applicable release rate(s) applied to all site areas tributary to the proposed pond discharge direction. All site tributary areas will be assumed as developed, regardless of whether all site tributary areas are proposed for development at that time. An exception shall be sites with multiple detention ponds in series where only the downstream pond must be designed to the stated release rate.

K. Where the site area to be impacted by a proposed development activity differs significantly from the total site area, only the proposed impact area shall be subject to the release rate criteria. The impact area includes any proposed cover or grading changes.

L. Development proposals which, through groundwater recharge or other means, do not increase either the rate or volume of runoff discharged from the site compared to predevelopment are not subject to the release rate provisions of this chapter.

M. No-harm water quantity option. For any proposed development site, the developer has the option of using a less restrictive runoff control if the developer can prove that special circumstances exist for the proposed development site and that no harm would be caused by discharging at a higher runoff rate than that specified by this chapter. Special circumstances are defined as any hydrologic or hydraulic aspects of the development itself not accommodated by the runoff control standards of this chapter. Proof of no harm would have to be shown from the development site through the remainder of the downstream drainage network to the confluence with the Lehigh River. Proof of no harm must be shown using the capacity criteria specified in § 137-13D of this chapter if downstream capacity analysis is a part of the no-harm justification.

(1) Attempts to prove no harm based upon downstream peak flow versus capacity analysis shall be governed by the following provisions:

(a) Any available capacity in the downstream conveyance system as documented by a developer may be used by the developer only in proportion to his development site acreage relative to the total upstream undeveloped acreage from the identified capacity (i.e., if his site is 10% of the upstream undeveloped acreage, he may use up to 10% of the documented downstream available capacity);

(b) Developer-proposed runoff controls which would generate increased peak flow rates at storm drainage problem areas would, by definition, be precluded from successful attempts to prove no harm; and

(c) Any downstream capacity improvements proposed by the developer as part of a no-harm justification would be designed using the capacity criteria specified in § 137-13D of this chapter. Peak flow contributions to the proposed improvements shall be calculated as the larger of 1) assuming the local watershed is in the existing condition, or 2) assuming that the local watershed is developed per current zoning and using the specified runoff controls.

(2) Any no-harm justifications shall be submitted by the developer as part of the drainage plan submission per Article 4 of this chapter. Developers submitting "no harm" justifications must still meet all of the water quality requirements of this chapter. The Township will process all eligible no-harm requests in accordance with § 137-14.1O of this chapter.

N. Capacity improvements. In certain instances, primarily within the Conditional/Provisional No Detention areas, 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. Peak flow calculations shall be done assuming that the local watershed is in the existing condition and then assuming that the local watershed is developed per current zoning and using the specified runoff controls. Any capacity improvements would be designed using the larger of the above peak flows and the capacity criteria specified in Subsection D of this section. All new development in 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.

O. Release rates need to be met year-round. Designs involving BMPs that function differently in winter versus nonwinter conditions (e.g., capture/reuse with spray irrigation shutoff for the winter) must still meet release rates during the winter.

§ 137-14 Calculation methodology.

A. Stormwater runoff from all development sites shall be calculated using either the Rational Method or the Soil Cover Complex Methodology.

B. Infiltration BMP loading rate percentages.

(1) Infiltration BMP loading rate percentages in the Recommendation Chart for Infiltration Stormwater Management BMPs in Carbonate Bedrock in Appendix D[1] shall be calculated as follows:

[1] Editor's Note: Appendix D is included as an attachment to this chapter.

(2) The area tributary to the infiltration BMP shall be weighted as follows:

(a) All disturbed areas to be made impervious: weight at 100%.

(b) All disturbed areas to be made pervious: weight at 50%.

(c) All undisturbed pervious areas: weight at 0%.

(d) All existing impervious areas: weight at 100%.

C. Soil thickness.

(1) Soil thickness is to be measured from the bottom of any proposed infiltration system. The effective soil thickness in the Recommendation Chart for Infiltration Stormwater Management BMPs in Carbonate Bedrock in Appendix D[2] is the measured soil thickness multiplied by the thickness factor based on soil permeability (as measured by the adapted 25 Pa. Code § 73.15 percolation test in Appendix G), as follows:[3]

Permeability Range1 (inches per hour)	Thickness Factor
6.0 to 12.0	0.8
2.0 to 6.0	1.0
1.0 to 2.0	1.4
0.75 to 1.0	1.2
0.5 to 0.75	1.0

NOTES:

If the permeability rate (as measured by the adopted 25 Pa. Code § 73.15 percolation test in Appendix G) falls on a break between two thickness factors, the smaller thickness factor shall be used.

[2] Editor's Note: Appendix D is included as an attachment to this chapter.

[3] Editor's Note: Appendix G is included as an attachment to this chapter.

(2) Sites with soil permeability greater than 12.0 inches per hour or less than 0.5 inch per hour, as measured by the adapted 25 Pa. Code § 73.15 percolation test in Appendix G, are not recommended for infiltration.

D. The design of any detention basin intended to meet the requirements of this chapter shall be verified by routing the design storm hydrograph through the proposed basin using the storage indication method or other methodology demonstrated to be more appropriate. For basins designed using the Rational Method technique, the design hydrograph for routing shall be either the Universal Rational Hydrograph or another rational hydrograph that closely approximates the volume of the Universal Rational Hydrograph.

E. BMPs designed to store or infiltrate runoff and discharge to surface runoff or pipe flow shall be routed using the storage indication method.

F. BMPs designed to store or infiltrate runoff and discharge to surface runoff or pipe flow shall provide storage volume for the full WQv below the lowest outlet invert.

G. Wet detention ponds designed to have a permanent pool for the WQv shall assume that the permanent pool volume below the primary outlet is full at the beginning of design event routing for the purposes of evaluating peak outflows.

H. All aboveground stormwater detention facilities shall provide a minimum 0.5 feet of freeboard above the maximum pool elevation associated with the two- through 100-year runoff events, or an additional 10% of the 100-year storage volume as freeboard volume, whichever is greater. All below-ground stormwater detention and infiltration facilities shall have an additional 10% of the 100-year storage volume available within the storage medium, as well as a minimum of 0.5 feet of freeboard. The freeboard shall be measured from the maximum pool elevation to the invert of the emergency spillway for aboveground facilities, and from the maximum pool elevation to the lowest overflow elevation for below-ground facilities. The two- through 100-year storm events shall be controlled by the primary outlet structure. An emergency spillway for each aboveground basin shall be designed to pass the 100-year return frequency storm peak basin inflow rate with a minimum 0.5 foot freeboard measured to the top of basin. The freeboard criteria shall be met considering any off-site areas tributary to the basin as developed, as applicable.

(1) Exceptions to the freeboard requirements are as follows:

(a) Bioretention BMPs with a ponded depth less than or equal to 0.5 foot are exempt from the freeboard requirements;

(b) Small detention basins, with a ponded depth less than or equal to 1.5 feet or having a depth to the top of the berm less than or equal to 2.5 feet, may provide 20% additional storage volume measured from the maximum ponded depth to the invert of the emergency spillway in lieu of the above requirements. The depth of the emergency spillway must be sufficient to pass either two times the 100-year peak or the 100-year peak with 0.2 foot of freeboard to the top of berm, whichever is greater; and

(c) Small infiltration basins, with a ponded depth less than or equal to 1.5 feet or having a depth to the top of the berm less than or equal to 2.5 feet, may provide 20% additional storage volume measured from the maximum ponded depth to the top of the berm in lieu of the above requirements. In this case, an emergency spillway is only necessary if runoff in excess of the basin volume would cause harm to downstream owners. If a spillway is necessary, it must be sufficiently sized to pass the 100-year peak inflow.

(2) If this detention facility is considered to be a dam as per DEP Chapter 105, the design of the facility must be consistent with the Chapter 105 regulations, and may be required to pass a storm greater than the 100-year event.

I. The minimum circular orifice diameter for controlling discharge rates from detention facilities shall be three inches. Designs where a lesser size orifice would be required to fully meet release rates shall be acceptable with a three-inch orifice, provided that as much of the site runoff as practical is directed to the detention facilities. The minimum three-inch diameter does not apply to the control of the WQv.

J. Runoff calculations using the Soil Cover Complex method shall use the Natural Resources Conservation Service Type II twenty-four-hour rainfall distribution. The twenty-four-hour rainfall depths for the various return periods to be used consistent with this chapter may be taken from NOAA Atlas 14, Precipitation Frequency Atlas of the United States, current volume, or the Pennsylvania Department of Transportation Drainage Manual, 2015 Edition, for Region 4. The following values are taken from the Drainage Manual:

Return Period	24-Hour Rainfall Depth
1-year	2.64 inches
2-year	3.16 inches
5-year	3.91 inches
10-year	4.57 inches
25-year	5.60 inches
50-year	6.53 inches
100-year	7.63 inches

A graphical and tabular presentation of the Type II, twenty-four-hour distribution is included in Appendix C of this chapter.[4]

[4] Editor's Note: Appendix C is included as an attachment to this chapter.

K. Runoff calculations using the Rational Method shall use rainfall intensities consistent with appropriate times of concentration and return periods and NOAA Atlas 14, Volume 2 Version 2.1, 2004, or the Intensity-Duration-Frequency Curves as presented in Appendix C of this chapter.

L. Runoff curve numbers (CNs) to be used in the Soil Cover Complex Method shall be based upon the matrix presented in Appendix C of this chapter.

M. Runoff coefficients for use in the Rational Method shall be based upon the table presented in Appendix C of this chapter.

N. All time of concentration calculations shall use a segmental approach which may include one or all of the flow types below:

(1) Sheet flow (overland flow) calculations shall use either the NRCS average velocity chart (Figure 3-1, Technical Release-55, 1975) or the modified kinematic wave travel time equation (Equation 3-3, NRCS TR-55, June 1986). If using the modified kinematic wave travel time equation, the sheet flow length shall be limited to 50 feet for designs using the Rational Method and limited to 150 feet for designs using the Soil Cover Complex Method.

(2) Shallow concentrated flow travel times shall be determined from the watercourse slope, type of surface and the velocity from Figure 3-1 of TR-55, June 1986.

(3) Open channel flow travel times shall be determined from velocities calculated by the Manning Equation. Bank-full flows shall be used for determining velocities. Manning N-values shall be based on the table presented in Appendix C of this chapter.

(4) Pipe flow travel times shall be determined from velocities calculated using the Manning Equation assuming full flow and the Manning N-values from Appendix C of this chapter.

O. If using the Rational Method, all predevelopment calculations for a given discharge direction shall be based on a common time of concentration considering both on-site and any off-site drainage areas. If using the Rational Method, all post-development calculations for a given discharge direction shall be based on a common time of concentration considering both on-site and any off-site drainage areas.

P. The Manning Equation shall be used to calculate the capacity of watercourses. Manning N-values used in the calculations shall be consistent with the table presented in Appendix C of this chapter or other appropriate standard engineering N-value resources. Pipe capacities shall be determined by methods acceptable to the Township Engineer.

Q. The DEP, 25 Pa. Code Chapter 105, Rules and Regulations apply to the construction, modification, operation or maintenance of both existing and proposed dams, water obstructions and encroachments throughout the watershed. Criteria for design and construction of stormwater management facilities according to this chapter may differ from the criteria that are used in the permitting of dams under the Dam Safety Program.

R. When conditions exist such that a proposed detention facility may experience a tailwater effect, the basin shall be analyzed without any tailwater effect for all storm events for comparison against the required release rates. An additional routing of the 100-year storm with the full tailwater effect shall be performed to check that the basin has sufficient storage to contain the 100-year tributary flow and meet freeboard requirements.

§ 137-14.1 Post-construction water quality criteria.

A. No regulated earth disturbance activities within the Township shall commence until approval by the Township of a drainage plan which demonstrates compliance with this chapter;

B. The Water Quality Volume (WQv) shall be captured and treated with vegetated/surface and/or direct recharge/subsurface BMPs. The WQv shall be calculated as the difference in runoff volume from predevelopment to post-development for the twenty-four-hour, two-year return period storm. This may be calculated using either the Soil Cover Complex Method or Rational Method using the two-year rainfall depth as noted in § 137-14J of this chapter. The effect of closed depressions on the site shall be considered in this calculation. The WQv shall be captured and treated in a manner consistent with the standards outlined in § 137-14.2 of this Chapter;

C. The WQv shall be calculated for each post-development drainage direction on a site for sizing BMPs. Site areas having no impervious cover and no proposed disturbance during development may be excluded from the WQv calculations and do not require treatment;

D. The applicant shall document the bedrock type(s) present on the site from published sources. Any apparent boundaries between carbonate and noncarbonate bedrock shall be verified through more detailed site evaluations by a qualified geotechnical professional;

E. For each proposed regulated activity in the watershed where an applicant intends to use infiltration BMPs, the applicant shall conduct a preliminary site investigation, including gathering data from published sources, a field inspection of the site, a minimum of one test pit and a minimum of two percolation tests, as outlined in Appendix G of this chapter.[1] This investigation will determine depth to bedrock, depth to the seasonal high water table, soil permeability and location of special geologic features, if applicable. This investigation may be done by a certified Sewage Enforcement Officer (SEO) except that the location(s) of special geologic features shall be verified by a qualified geotechnical professional;

[1] Editor's Note: Appendix G is included as an attachment to this chapter.

F. Sites where applicants intend to use infiltration BMPs must meet the following criteria:

(1) Depth to existing bedrock below the invert of the BMP greater than or equal to two feet;

(2) Depth to seasonal high water table below the invert of the BMP greater than or equal to two feet; except for infiltration of residential roof runoff where the seasonal high water table must be below the invert of the BMP;

(3) Soil permeability (as measured using the standards listed in Appendix C of the Pennsylvania Stormwater Best Practices Manual) greater than or equal to 0.1 inch/hour and less than or equal to 10 inches per hour;

(4) Setback distances or buffers as follows:

(a) One hundred feet from water supply wells, or 50 feet in residential development;

(b) Ten feet downgradient or 100 feet upgradient from building foundations;

(5) Fifty feet from septic system drainfields;

(6) Fifty feet from a geologic contact with carbonate bedrock, unless a preliminary site investigation is done in the carbonate bedrock to show the absence of special geologic features within 50 feet of the proposed infiltration area;

G. In entirely carbonate areas, where the applicant intends to use infiltration BMPs, the preliminary site investigation described in Appendix G of this chapter[2] shall be conducted. For infiltration areas that appear feasible based on the preliminary site investigation, the applicant shall conduct the additional site investigation and testing as outlined in Appendix G of this chapter. The soil depth, percolation rate and proposed loading rate, each weighted as described in § 137-14B of this chapter, along with the buffer from special geologic features shall be compared to the Recommendation Chart for Infiltration Stormwater Management BMPs in Carbonate Bedrock in Appendix D[3] of this chapter to determine if the site is recommended for infiltration. In addition to the recommendation from Appendix D of this chapter, the conditions listed in § 137-14.1F of this chapter are required for infiltration in carbonate areas;

[2] Editor's Note: Appendix G is included as an attachment to this chapter.

[3] Editor's Note: Appendix D is included as an attachment to this chapter.

H. Site areas proposed for infiltration shall be protected from disturbance and compaction except as necessary for construction of infiltration BMPs;

I. If infiltration of the entire WQv is not proposed, the remainder of the WQv shall be treated by acceptable BMPs for each discharge location. Acceptable BMPs are listed in Appendix H of this chapter;[4]

[4] Editor's Note: Appendix H is included as an attachment to this chapter.

J. Stormwater runoff from hot spot land uses shall be pretreated. Suggested methods of pretreatment are listed in Appendix H of this chapter;

K. The use of infiltration BMPs is prohibited on hot spot land use areas, unless the applicant can demonstrate that existing and proposed site conditions, including any proposed runoff pretreatment, create conditions suitable for runoff infiltration under this chapter;

L. Stormwater infiltration BMPs shall not be placed in or on a special geologic feature(s). Additionally, stormwater runoff shall not be discharged into existing on-site sinkholes;

M. Stormwater drainage wells may only be used for runoff from roof areas;

N. Applicants shall request, in writing, public water suppliers to provide the Zone I wellhead protection radius, as calculated by the method outlined in the Pennsylvania Department of Environmental Protection Wellhead Protection regulations, for any public water supply well within 400 feet of the site. In addition to the setback distances specified in § 137-14.1F of this chapter, infiltration is prohibited in the Zone I radius as defined and substantiated by the public water supplier in writing. If the applicant does not receive a response from the public water supplier, the Zone I radius is assumed to be 100 feet; and

O. The municipality may, after consultation with DEP, approve alternative methods 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.[5]

[5] Editor's Note: See 35 P.S. § 691.1 et seq.

§ 137-14.2 Green infrastructure and existing water balance preservation standards.

A. The entire WQv as calculated in § 137-14.1B of this chapter shall be captured and treated by either direct recharge/subsurface and/or vegetated/surface BMPs.

B. As much proposed impervious area as practical shall be directed to water quality BMPs.

C. Existing impervious area that is not proposed to be treated by direct recharge/subsurface BMPs should be excluded from all water balance calculations.

D. Vegetated/surface BMPs shall be employed first for the site to capture the equivalent of a minimum of 0.38 inches of runoff for each square foot of impervious area, unless proven not feasible by the applicant. For proposed impervious cover directed to multiple BMPs, the vegetated/surface BMP capture volume chart in Appendix C[1] shall be used to determine overall site compliance. Direct recharge/subsurface BMPs may be used first for portions of the impervious cover, provided the overall vegetated/surface BMP first standard is met.

[1] Editor's Note: Appendix C is included as an attachment to this chapter.

E. A maximum of 30% of the total annual rainfall for a site may be directly recharged to groundwater using direct recharge/subsurface BMPs, for runoff from impervious areas.

(1) For development sites with greater than 33% proposed impervious cover:

(a) If all impervious cover is directed to vegetated/surface BMPs to capture the entire two-year, twenty-four-hour event, the direct recharge standard is met;

(b) Up to 33% of the site as impervious cover may be directed to direct recharge/subsurface BMPs designed to capture the entire two-year, twenty-four-hour event, provided the overall vegetated/surface BMP first standard is met. All remaining impervious cover shall be directed to vegetated/surface BMPs designed to capture the remainder of the WQv; and

(c) For vegetated/surface and/or direct recharge/subsurface BMPs designed for runoff from impervious areas designed to capture less than the entire two-year, twenty-four-hour event, Appendix C[2] shall be used to assure that the maximum direct recharge standard is met.

[2] Editor's Note: Appendix C is included as an attachment to this chapter.

(2) The maximum 30% direct recharge standard applies on an overall site basis, rather than in each drainage direction.

§ 137-15 through § 137-16. (Reserved)

§ 137-17 Stormwater infiltration.

A. Infiltration practices shall be designed and constructed in accordance with the standards in Appendix A.[1]

[1] Editor's Note: Appendix A is included as an attachment to this chapter.

B. All stormwater runoff from residential (principal and accessory) structures which have a cumulative square footage of 1,200 square feet or greater shall be infiltrated in an infiltration practice with a void volume equal to three inches over the impervious surface, with a minimum cover of one foot, and which has a footprint area of at least 1/5 the size of the proposed impervious area. Probes shall be performed to determine the required vertical separations from limiting zones; however, no percolation testing is required. Where geologic or soil evaluations do not support infiltration, the stormwater flow rate shall be regulated so as to not exceed 0.25 cubic foot per second greater than predevelopment rates during the two-, ten-, twenty-five-, and 100-year storms.

§ 137-18 Detention basins.

Detention facilities shall be permitted only where the geology of the tract being developed precludes the use of infiltration volume control and only to the extent that geology precludes infiltration, or as may be allowed by the Township only where unique physical circumstances of the development property exist. Permission to use detention facilities shall not be granted for economic reasons. Where the Township allows detention facilities, such detention facilities shall be designed in accordance with the following requirements:

A. The detention facilities shall be designed to retard stormwater runoff rates after development to the peak runoff rate established by this chapter.

B. Detention facility spillways shall be protected from erosion.

C. Detention facility pipe outlet arrangements shall provide complete outletting of all detained water, unless provisions for permanent ponding have been approved by the Township Council. Basin forebay infiltration areas may be allowed on a case-by-case basis if it is deemed the most suitable BMP applicable to the site.

D. Detention pond lining and carbonate geology requirements.

(1) A detention facility, if utilized, shall be lined with an impervious lining in areas of carbonate geology. This liner shall be constructed to meet the following minimum requirements:

(a) The minimum liner required is 30 mil PVC and must be UV-resistant. Actual individual liner specifications shall be provided by the manufacturer for each individual facility.

(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 facility 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 floodwater elevation in the facility.

(2) If a detention facility is proposed without lining, the developer's engineer/surveyor must sign and seal the following note which shall be attached to all drainage plans, subdivision plans, and land development plans: "I, [name], certify that the proposed facility(ies) is/are not underlain by carbonate geology."

(3) Basins shall not be placed where prohibited by the carbonate geology area requirements of Chapter 180, Zoning, of the Code of the Township of Lower Saucon.

E. The minimum circular orifice diameter for controlling discharge rates from detention facilities shall be three inches. Designs where a lesser size orifice would be required to fully meet release rates shall be acceptable with a three-inch orifice, provided that as much of the site runoff as practical is directed to the detention facilities.

F. The detention facility shall be planted with wet-tolerant wildflower or low-maintenance grass satisfactory to the Township. Detention basins shall be planted with ground cover in accordance with Township standards.

G. An access ramp of 10 to 1, 10 feet wide, shall be provided to allow maintenance equipment to reach the basin floor.

H. Where allowed by waiver of Council, fencing for detention basins shall provide a suitable barrier, at least four feet in height, of material approved by the Township, such as 0.4 retention pressure treated wooden post-and-rail fence (three-rail) with black vinyl-coated metal hardware fabric. Access to the basin shall be provided by a locking gate or gates, having a total opening of at least 10 feet, at such a location as to provide ready access to the detention basin by maintenance forces with maintenance equipment or suitable equivalent approved by the Township during the plan review. The fence shall be at least three feet from the inside edge of the berm (or top of slope) or five feet from the outside top of the berm.

I. Landscaping, subject to approval of the Township, shall be provided adjacent to the detention facility so as to provide a buffer between the facility and the adjacent development. If a fence is required, the detention basin fence shall be screened in accordance with improvements construction standards, as outlined in SALDO.[1]

[1] Editor's Note: See Ch. 145, Subdivision and Land Development.

J. Where no fence is included, detention basin berms shall have a minimum width of six feet.

K. In all cases, the outside slope of a berm shall not be steeper than a ratio of 3:1, horizontal to vertical.

L. To minimize the visual impact of detention basins, basins shall be designed to avoid the need for safety fencing. To meet this requirement, basins shall be designed to the following specifications:

(1) The maximum depth of detained runoff shall be 24 inches for a two-year or ten-year storm event.

(2) The maximum depth of detained runoff shall be 36 inches for a 100-year storm event.

(3) Interior slopes shall not be steeper then a ratio of 5 to 1 horizontal to vertical.

(4) The basin shall never exceed a depth of 24 inches for more than four hours.

(5) Basins shall drain completely within eight hours of the end of the rainfall.

(6) These depths and slopes may be exceeded by permission of the Township on a case-by-case basis for detention basin areas having a natural slope greater than 5% and/or having substantial woodland ground cover. In such a case, fence and landscape screens will be required. These requirements shall not be waived for economic reasons.

M. If fencing is allowed by waiver of Council, and a basin is proposed to be dedicated to the Township, the basin design shall provide a level area (2% slope), 12 feet in width, on both the inside and outside of the fence, along the entire length of the fence for proper access by Township maintenance equipment. The total width of this generally level area shall be at least 24 feet.

N. The minimum slope of the bottom of a detention facility shall be 1% toward the outlet structure, except for approved BMP areas.

O. All stormwater detention facilities shall provide a minimum 1.0 foot freeboard above the maximum pool elevation associated with the two-year through twenty-five-year runoff events. A 0.5-foot freeboard shall be provided above the maximum pool elevation of the 100-year runoff event. The freeboard shall be measured from the maximum pool elevation to the elevation of the emergency spillway. The two-year through 100-year storm events shall be controlled by the primary outlet structure. An emergency spillway for each basin shall be designed to pass the 100-year return frequency storm peak basin inflow rate, as if the basin were full prior to the storm, with a minimum 0.5-foot freeboard measured to the top of basin. The freeboard criteria shall be met considering any off-site areas tributary to the basin as developed, as applicable. If this detention facility is considered to be a dam as per DEP Chapter 105,[2] the design of the facility must be consistent with the Chapter 105 regulations, and may be required to pass a storm greater than the 100-year event.

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

P. The detention basin 100-year water storage surface elevation perimeter shall be shown on all plans. Principal residential structures shall be set back 100 feet from any detention basin 100-year water storage surface elevation perimeter. Where this setback is more restrictive than the zoning setback, the new setback line shall be shown on the plan with a dimension to the 100-year water storage surface elevation perimeter provided. Accessory residential structures and all nonresidential structures shall be set back 25 feet from any detention basin 100-year water storage surface elevation perimeter.

Q. Soils used for the construction of basins shall have low-erodability factors ("K" factors).

R. All detention facility outflows, including emergency spillways, shall comply with §§ 137-11F, 137-19D and 137-23K.

S. The top of slope or toe of outside slope of any detention or retention basin shall be no closer than 50 feet from any property line, or ultimate right-of-way line.

§ 137-19 Collection systems.

A. Fixed pipe collection system. The Township may require a fixed-pipe collection system with inlets. Such fixed-pipe collection system with inlets shall be used in all areas with street curbs and gutters, when required.

B. Low-point drainage. The developer shall grade and install all necessary stormwater management facilities to ensure the drainage of all low points on subdivided lots or within the subdivision or developed land areas (except in areas of protected lakes, ponds, or wetlands, vernal ponds and in approved infiltration practices). Underdrains are required at a minimum of 50 feet upward from a road low point along each side of each approach road to the low point.

C. Street drainage. All streets shall be designed so as to provide for the discharge of surface water from their rights-of-way. Concentrated discharges of stormwater from rights-of-way shall be directed to an acceptable watercourse, pipe, culvert or swale.

D. Stormwater discharge.

(1) Concentrated stormwater runoff to downstream properties, including piped storm sewer system outlets, detention facility discharge structures and swales shall discharge into an adequately sized watercourse or storm sewer system after meeting all required release rate criteria. (See also § 137-23K.) If a level spreader is incorporated within the design of the outlet system, the post-development peak rate of discharge across the width of the level spreader shall not exceed the predevelopment peak flow across the same width at the same location. Level spreaders shall be located a minimum of 100 feet from the downstream limit of any drainage easement boundary under the control of the developer and no closer than 100 feet to an existing or ultimate public road right-of-way.

(2) Level spreaders shall be designed to remain level and to resist frost-related movement.

E. Capacity for design storms:

(1) Unless a more conservative design is required by another regulation or is required because of conditions particular to an individual development, the following storm criteria shall be used to design storm collection and conveyance systems:

Area	Design Storm Return (years)
Residential areas
Fixed pipe	10
Total conveyance	100
Nonresidential areas
Fixed pipe	25
Total conveyance	100
Culvert crossings of any road
In culvert	25
Total conveyance	100

(2) Adequate overland conveyance of the 100-year storm must be provided to any detention basin or other stormwater management facility designed to manage runoff from the 100-year storm assuming all stormwater inlets are clogged. Conveyance of the 100-year storm to infiltration practices must be assured.

F. Open swales and gutters. Open swales shall be designed on the basis of Manning Formula, as indicated for collection systems, with the following considerations:

(1) Roughness coefficient. The roughness coefficient shall be 0.040 for vegetated swales.

(2) Bank slopes. Slopes for swale banks shall not be steeper than one vertical for three horizontal.

(3) Flow velocity. Design velocity in grass or vegetated swales shall not exceed four feet per second.

(4) Swale right-of-way and easement width. Swale right-of-way or easements shall be sufficiently wide to include a ten-foot access strip in addition to the width of the swale from the bank top. The Township may, under unusual conditions, require a wider swale right-of-way.

(5) Swales adjacent to road paving which meet the Township standards for roadside swales shall be permitted to carry a maximum flow of five cubic feet per second for the ten-year design storm return in residential areas and the twenty-five-year design storm return in nonresidential area prior to discharge away from the street surface, unless it is proven to the satisfaction of the Township by engineering calculations that the road slopes or other factors would allow higher swale capacity. Gutter flow along a curb shall not be permitted to exceed 1/2 of a travel lane in width, for the twenty-five-year design storm return.

(6) Flows larger than those permitted in gutters and roadside swales may be carried in swales outside the required road right-of-way in separate drainage easements or may be carried in pipes or culverts inside or outside the required road right-of-way.

(7) Swales shall be stabilized with vegetation or other materials approved by the Township to prevent erosion.

(8) Paved swales are not permitted.

G. Fixed pipe collection system standards. Culverts, drainage structures and other parts of the stormwater drainage system that are not open swales or gutters shall be designed on the basis of Manning Formula, as indicated for collection systems, with the following considerations:

(1) Inlets. Curb inlets shall be located at curb tangents on the uphill side of street intersections. The design and location of curb inlets shall be approved by the Township. The collection capacity of curbed inlets is to be determined using PennDOT standard efficiency charts for the capture capacity of Type C inlets.

(a) Gutter flows shall not be permitted across street intersections.

(b) All inlets shall be labeled with an embedded plastic disk indicating a prohibition against pollutants.

(2) State approvals. Drainage structures that are located on state highway rights-of-way shall be approved by the Pennsylvania Department of Transportation, and a copy of the highway occupancy permit shall be submitted to the Township.

(3) Pipe materials. Existing storm piping shall be extended using the same pipe materials to the next connected stormwater structure. Otherwise, all storm piping shall be new Class III reinforced concrete piping with O-ring joints, or smooth-lined HDPE pipe, with watertight joints. All storm piping shall meet all requirements of PennDOT. Piping shall be saw cut at the ends, as needed, and not hammered or broken.

(4) Minimum pipe size. Minimum pipe size shall be 15 inches.

(5) Minimum pipe slope. The minimum pipe slope shall be 0.5%.

(6) Minimum ground cover. The minimum cover shall be 12 inches from finished grade to the top of the pipe. A minimum cover shall be 18 inches from the top of the cartway to the top of the pipe.

(7) Maximum pipe length. Storm sewer piping shall have a maximum length of 300 feet between junction boxes, manholes or inlets which would allow access and cleaning from the surface of the ground.

(8) Inlet and manhole construction. Inlet and manhole castings and concrete construction shall be equivalent to Pennsylvania Department of Transportation design standards. A cover of at least four inches shall be provided above any pipe in any proposed concrete structure which is subject to vehicular traffic.

(9) Roof drainage. Stormwater roof drains and pipes shall not discharge water over impervious areas.

(10) Open-end pipes must be fitted with concrete end walls or wing walls in accordance with PennDOT standards. Flared end sections are not permitted. In addition, all end walls, wing walls and detention facility outlet control structures shall be provided with a concrete footings that extend below the frost line for scour and frost protection. This concrete footing shall be a minimum depth of 30 inches below ground level.

(11) Upstream open culvert headwalls or wing walls for pipes shall be fitted with slanted durable protective grates.

(12) No end of a storm sewer pipe shall be permitted inside the ultimate road right-of-way. An exception to this requirement is in cases where new driveways must cross existing deep roadside swales adjacent to existing roads. In the case of this exception to the standard, the pipe shall be located as far off the edge of pavement as possible (at least 16 feet from the road center line) and shall be adequately sized by a professional engineer per this chapter.

(13) Flow velocity. Storm drains shall be designed to produce a minimum velocity of 3.0 feet per second when flowing full. The maximum permissible velocity shall be 15.0 feet per second.

(14) Fixed pipe conveyance of stormwater must be to the same destination (detention basin, off-site point of study, etc.) as stormwater would be conveyed overland if the fixed pipe conveyance system were to fail.

(15) All concentrated stormwater discharge directed toward public right-of-way shall be captured into the fixed pipe collection system.

(16) Inlets and manholes shall be spaced at intervals not exceeding 300 feet and shall be located wherever branches are connected or sizes are changed and wherever there is a change in alignment or grade.

(17) Inlets shall have sufficient capacity to accept design flows.

(18) Carbonate geology. In areas of carbonate bedrock and in carbonate geologic areas as defined in Chapter 180, Zoning, of the Code of the Township of Lower Saucon, mortar joint and metal-banded sewer piping is prohibited.

(19) Storm drainage system discharges shall not be directed toward any of the carbonate features.

(20) All nonsumped structures shall have its lowest invert out at least 0.1 foot lower than its lowest invert in. All sumped structures shall have its lowest invert "out" at least as high as the highest invert "in" unless an oil/water separator is utilized.

H. Bridges and culverts. Bridges and culverts shall be designed to support expected loads, to carry expected flows and to be constructed to the full width of the right-of-way. Such bridges or culverts shall be designed in accordance with Pennsylvania Department of Transportation construction standards. Separate design plans and specifications shall be required for each bridge and culvert, which plans and specifications shall be subject to review and approval of the Township.

I. Design conditions. All storm drainage systems shall be designed in accordance with PennDOT Design Manual 2 Chapter 10 requirements. For storm drainage systems which are not proposed within PennDOT right-of-way, an exception shall apply such that any requirement contained in a Township chapter shall supersede any directly conflicting requirement of PennDOT Design Manual 2 Chapter 10.

J. Flood protection. All storm drainage calculations for facility sizing and for flood conveyance and flood protection shall be provided using the assumption that the contributing undeveloped upstream watershed is developed in conformance with regulations of the current Chapter 180, Zoning.

§ 137-20 Permanent erosion and sediment control.

A. Special structures, such as check dams, drop outlets or other energy-dissipating structures or riprap may be required to prevent scour or erosion in locations with large runoff quantities or steep slopes. In no case may a change be made in the existing topography which would result in a slope exceeding the normal angle of slippage of the material involved. No paved swales will be allowed without the approval of the Township.

B. Energy dissipaters shall be placed at the outlets of all pipes.

C. Erosion and sedimentation control measures shall be in accordance with the applicable state and county standards and specifications.

§ 137-21 Erosion and sediment control during regulated earth disturbance activities.

A. No regulated earth disturbance activities within the Township shall commence until approval by the Township of an erosion and sediment control plan for construction activities. Written approval by DEP or a delegated county conservation district shall satisfy this requirement.

B. An erosion and sediment control plan is required by DEP regulations for any earth disturbance activity under 25 Pa. Code § 102.4(b).

C. A DEP NPDES stormwater discharges associated with construction activities permit is required for regulated earth disturbance activities under 25 Pa. Code Chapter 92.

D. Evidence of any necessary permit(s) for regulated earth disturbance activities from the appropriate DEP regional office or county conservation district must be provided to the Township before the commencement of an earth disturbance activity.

E. A copy of the erosion and sediment control plan and any permit, as required by DEP regulations, shall be available at the project site at all times.

F. All construction shall be done in accordance with the approved erosion and sedimentation control plan.

§ 137-22 Permit requirements by other government entities.

A. The following permit requirements apply to certain regulated and earth disturbance activities and must be met prior to commencement of regulated and earth disturbance activities, as applicable:

(1) All regulated and earth disturbance activities subject to permit requirements by DEP under regulations at 25 Pa. Code Chapter 102.

(2) Work within natural drainageways subject to permit by DEP under 25 Pa. Code Chapters 102 and 105.

(3) Any stormwater management facility that would be located in or adjacent to surface waters of the commonwealth, including wetlands, subject to permit by DEP under 25 Pa. Code Chapter 105.

(4) Any stormwater management facility that would be located on a state highway right-of-way or require access from a state highway or discharge onto a state highway right-of-way shall be subject to approval by the Pennsylvania Department of Transportation (PennDOT).

(5) Culverts, bridges, storm sewers or any other facilities which must pass or convey flows from the tributary area and any facility which may constitute a dam subject to permit by DEP under 25 Pa. Code Chapter 105.

B. All plans with all supporting calculations submitted to government agency for review to receive permits shall have substantially the same design as the drainage plan submitted for review by the Township; a copy of all plans, with supporting calculations, which have received a government agency permit, shall be provided to the Township and Township Engineer.

§ 137-23 Additional design requirements.

A. All stormwater management facilities proposed shall be designed in accordance with Chapter 145, Subdivision and Land Development, of the Code of Lower Saucon Township, and the general design and construction standards of this chapter.

B. Lots shall be graded to secure proper drainage away from buildings and, to the extent possible, away from street areas, except streets where curbs, storm sewer piping system or roadside swales exist.

C. (Reserved)

D. The developer shall construct and/or install such drainage structures and/or pipes which are necessary to prevent erosion damage and to satisfactorily manage surface waters in accordance with Pa. Code Title 25, Rules and Regulations, Part I, Commonwealth of Pennsylvania Department of Environmental Protection, Subpart C, Protection of Natural Resources, Article II, Water Resources, Chapter 102, Erosion Control. Any drainage system not operating as planned or which causes downstream damage shall be corrected at the expense of the developer.

E. No person, firm, or corporation shall modify, fill, excavate or regrade the land in any manner as to endanger or damage any adjoining public street, sidewalk, alley or any other public or private property without supporting and protecting such property from settling, cracking, erosion, sediment, stormwater ponding (except in those cases where ponding is approved) or other physical damage or personal injury which might result. Such activity without the required support or protection will constitute a nuisance punishable by the provisions of this chapter.

F. No person, firm or corporation shall deposit or place any debris or other material whatsoever, or cause such to be thrown or placed, in any drainage ditch or drainage structure in such a manner as to reduce the ability of the stormwater management facility to operate.

G. Stockpiling of topsoil shall be protected from erosion.

H. All disturbed areas shall be seeded, sodded and/or planted or otherwise protected from erosion within 60 days of ground-breaking, and shall be watered, tendered and maintained until growth is well established. If state regulations require a shorter time, the shorter time shall be required

I. All permanent grading shall be designed and undertaken to meet the following criteria:

(1) Provide positive surface drainage away from on-site sewage disposal systems;

(2) Provide positive surface drainage away from buildings and structures; and

(3) Provide that no cutting or filling, either temporarily or permanently, shall be allowed to occur within two feet of any side or rear property line, except at locations where specific grading and/or drainage easements exist for the purposes of such grading.

J. The developer shall limit stormwater runoff rate and concentration from the subject lot to other lands in a manner that will minimize risk of damage to downstream property owners.

K. Stormwater discharge facilities outletting water to the surface of the ground shall be designed and constructed to meet the following criteria in addition to other regulations:

(1) Stormwater roof drains and any sump pump drains shall not discharge water directly onto a sidewalk, a lane, or a street, or within the street, or within the street right-of-way and shall not direct water toward improved portions of adjacent lots (i.e., buildings, driveways, on-lot sewer facilities, etc.).

(2) Stormwater roof drains and sump pump drains shall be constructed to disperse the discharge on the lot which is the subject of the application or to an approved stormwater system.

(3) Any stormwater outlet pipe (including detention basin outlet pipe) or structure (including detention basin spillway) that discharges water to the surface of the ground shall be located no closer than 100 feet from an adjacent property line or right-of-way line and shall discharge into a drainage channel, swale or pipe within a drainage easement that has been designed, constructed and/or analyzed to receive the water discharge from that outlet. Emergency overflow pipes from subsurface infiltration facilities may be located within 20 feet of a property or right of way line if the pipe is designed to provide for emergency relief only. Downspout pipes discharging stormwater runoff from portions of a roof of less than 500 square feet of roof area shall be exempt from this regulation if the following criteria are met:

(a) The outlet shall be located no closer than five feet from a property line;

(b) A standard splash pad or apron shall be provided to spread the flow; and

(c) A swale or ground slope shall be provided or available to protect the immediate adjacent downstream property.

(4) If a stormwater outlet pipe discharges in the direction of a public right-of-way, the alignment of that discharging stormwater shall be within an angle of 20° or less to a line parallel to the roadside swale or gutter, unless inlet facilities are provided to relieve that flow.

L. All persons, firms or corporations shall adequately operate, maintain, repair, restore and/or replace (if necessary) any stormwater management facility on its premises to keep them in good operating condition. For example, all watercourses, drainage ditches, culverts, drainpipes, infiltration facilities, detention basins and structures shall be kept open and operating at all times.

M. No ground may be proposed or altered to exceed a slope steeper than one vertical for three horizontal.