Township of Marlborough, PA Design Standards

General.

The management of stormwater on a site, both during and upon completion of the disturbances associated with a proposed subdivision or land development, or associated with building construction and other land disturbance activities, shall be accomplished in accordance with the standards and criteria of this section.

(2)

All drainage provisions shall be of such design as to carry surface water to the nearest practical infiltration facility, swale, storm sewer, detention basin, or natural watercourse.

(3)

The developer or applicant shall construct and/or install such stormwater facilities (BMPs) which are necessary to control stormwater runoff and erosion damage.

(4)

All storm sewer and drainage facilities, such as infiltration facilities, catch basins, inlets, detention basins, swales, bridges and culverts, shall be installed, and the land graded, for adequate drainage as shown on the stormwater and erosion control plan submitted, approved and prepared in accordance with Articles III and IV herein.

(5)

Design of storm drainage facilities (BMPs) shall be completed in accordance with accepted engineering practices, subject to approval by the Township Engineer.

(6)

Wherever construction stops or concentrates the natural flow of storm drainage in such a way as to affect adjoining properties, approval by the owners of all affected properties shall be obtained in writing and a copy filed with the Township. Approval of plans by the Township does not authorize or sanction drainage affecting adjoining properties and does not constitute a representation of any kind relating to the potential damage which may or may not result from such drainage.

(7)

Water originating from other than natural sources, such as air-conditioning units, swimming pools, sump pumps, or other dry-weather flow, wherever practicable, shall be discharged across lawn/meadow/wooded areas into natural watercourses on the property. The discharge of such water under the sidewalk through the curb into the street gutter is prohibited unless no other feasible discharge point is found.

(8)

The discharge of any type of water directly onto adjacent properties is prohibited. Grading shall be such that surface and roof runoff travel along the property lines to the closest BMP.

(9)

Existing stream channels shall be maintained in their natural state. Only under unusual circumstances will it be permitted to line, straighten, or relocate an existing stream, and such activities shall be only with the permission of any or all agencies having jurisdiction, including, but not limited to, the Federal Emergency Management Agency, the Pennsylvania Department of Environmental Protection, the Pennsylvania Department of Transportation, and the Montgomery County Conservation District, as well as the Township, or other affected municipalities.

(10)

The design of any stormwater management plan shall contemplate and provide for corrective measures to existing stormwater problems that originate in whole or in part on the property to be disturbed or that would impact the end users of a proposed development. Such corrective measures may include on-site and off-site improvements.

(11)

Stormwater control facilities (BMPs) shall be required, including, but not limited to, when one of the following conditions is present:

(a)

Runoff from proposed development will exceed the capacity of downstream facilities;

(b)

Runoff from a proposed parking facility or building will increase the peak discharge from the existing conditions;

(c)

A subdivision or land development, as defined by the Marlborough Township Subdivision and Land Development Ordinance, is proposed;

(d)

Construction activities meet the definition of a regulated earth disturbance; and

(e)

Stormwater control facilities (BMPs) are necessary for the protection of the public health, safety and welfare as determined by the Township Supervisors.

(12)

Recharge facilities, detention facilities, storm sewers, culverts, bridges and related drainage installations shall be designed and constructed to meet the following purposes:

(a)

To permit unimpeded flow of natural watercourses. Such flow may only be redirected when unavoidable, subject to the approval of the Pennsylvania Department of Environmental Protection;

(b)

To ensure adequate drainage of all low points as may be related to streets;

(c)

To intercept stormwater runoff along streets at intervals reasonably related to the extent and grade of the area drained to prevent flow of stormwater across intersections and into travel lanes during the design storm;

(d)

To ensure adequate and unimpeded flow of stormwater under driveways in, near, or across natural watercourses or drainage swales. Properly sized pipes or other conduits shall be provided as necessary;

(e)

To prevent excessive flow on or across streets, sidewalks, drives, parking areas, and any other paved surface or accessway; and

(f)

To lead stormwater away from springs.

(13)

When storm drainage will be directed into an adjacent municipality, all provisions for accommodating such storm drainage shall be submitted to the governing body of that municipality for review.

Stormwater management design philosophy. Stormwater management facilities (BMPs) shall be provided in order to control the volume, discharge, and quality of stormwater runoff from the entire site in accordance with the following:

(1)

The choice and design of stormwater management systems are to be developed through a procedure that selects and locates BMPs, viewing components in the following priority:

(a)

Seeking to control runoff at its source through infiltration;

(b)

Improving the quality of the stormwater during conveyance; and

(c)

Providing for detention.

(2)

The choice and design of stormwater management facilities used to meet the requirements of this section shall be based on the system types and specifications set forth in the Pennsylvania Handbook of Best Management Practices for Developing Areas, published by the Commonwealth of Pennsylvania. The use of other control methods, such as those contained in other publications that provide the desired controls established in this chapter, may be permitted if approved by the Township Engineer. Various combinations of methods are encouraged and should be tailored to suit the particular requirements for the type of development and the local site conditions.

Site discharge and runoff volume requirements.

(1)

Stormwater management facilities (BMPs) shall be provided such that, after installation of the proposed stormwater management facilities, stormwater runoff from the entire site shall be in accordance with the following:

(a)

During a two-year frequency storm, the maximum discharge from the site after construction shall be no greater than from a one-year frequency storm before construction.

(b)

During a five-year frequency storm, the maximum discharge from the site after construction shall be no greater than from a two-year frequency storm before construction.

(c)

During a ten-year frequency storm, the maximum discharge from the site after construction shall be no greater than from a five-year frequency storm before construction.

(d)

During the twenty-five-, fifty- and one-hundred-year frequency storms, the maximum discharge from the site after construction shall be no greater than from the twenty-five-, fifty- and one-hundred-year frequency storms before construction, respectively.

(e)

During a two-year frequency storm, the maximum volume of runoff from the site after construction shall be no greater than from a two-year frequency storm before construction. The difference in the two-year runoff volume, if any, must be infiltrated.

(f)

Under certain conditions, the Township, upon recommendation of the Township Engineer, may impose the following additional restrictions on stormwater discharges:

[1]

Peak discharge may be further restricted when it can be shown that a probable risk to downstream structures or unique natural areas exists or that existing severe flooding problems could be further aggravated.

[2]

Measures shall be imposed to protect against ground- or surface water pollution where the type of business activity may result in significant non-point-source pollution ("hot spots") or the nature of the soils or bedrock underlying a stormwater management structure constitutes substantial risk of contamination, such as might be the case in limestone formations. Special provisions to be followed in these cases will be provided by the Township Engineer.

[3]

Where groundwater yields are very low or where a groundwater supply already is heavily used, the Township may require that the entire volume of the two-year frequency rainfall (3.2 inches in 24 hours) be retained and infiltrated.

[4]

Only after the Township Engineer confirms that the use of infiltration systems is not realistic, and therefore the volume of runoff controls per § 202-24C(1)(e) cannot be achieved on the site due to existing soil characteristics, bedrock, water table, or other conditions on the parcel, then it shall be provided that 18 hours after the peak volume of a one-year frequency storm occurs, 10% of the peak volume remains in the basin.

(2)

Significant loadings of non-point-source pollutants shall not be discharged into either surface water or groundwater. "Significant" is defined as resulting in an increase greater than 10% of existing background concentrations of all water quality parameters of consequence identified in federal and state criteria for the watershed. In particular, nutrients (nitrate and total phosphorus), metals (cadmium and lead), total petroleum hydrocarbons (PH) and synthetic organic compounds identified by the United States Environmental Protection Agency (EPA) as toxic or hazardous substances must be controlled. If the volume and peak rate standards above [§ 202-24C(1)(a) through (e)] are met, then water quality impacts are assumed to be adequately controlled. If the volume standard [§ 202-24C(1)(e)] above cannot be achieved, in order to mitigate the potential polluting of surface waters and groundwaters by pollutants such as salt, petroleum products, and antifreeze flowing from paved parking lots, pretreatment of the runoff shall be required. The extent of the treatment shall be set by the Township Engineer and will be determined by such factors as the area of the parking lot or areas and the course of the runoff as it is recharged or flows into natural waterways.

Infiltration systems.

(1)

The United States Department of Agriculture, Soil Conservation Service, TR-55 method shall be used to determine the volume of runoff to be infiltrated (inches of runoff multiplied by the acreage of the contributing drainage area).

(2)

Infiltration systems shall be selected based on suitability of soils and site conditions.

(3)

Measures may include underground infiltration beds located under paved areas, vegetated infiltration beds, swales and trenches, or other structures that allow for seepage of stormwater from the structure.

(4)

The infiltration system type and construction details shall be approved by the Township Engineer.

(5)

Soil infiltration tests shall be performed for all proposed infiltration areas; these tests shall include evaluation of selected soil horizons by deep pits and percolation measurements. Testing methods shall be reviewed and approved by the Township Engineer. When used in the proposed design, the soil infiltration rate of discharge from the infiltration area shall be based on these measurements.

(6)

The soil infiltration rate of discharge from infiltration areas shall not be used in the proposed detention design due to both short- and long-term concerns regarding proper operation of such systems.

(7)

The lowest elevation of the infiltration system shall be at least two feet above the seasonal high-water table.

(8)

The lowest elevation of the infiltration system shall be at least two feet above bedrock, except in the case of limestone formation, in which case the distance shall be three feet.

(9)

All infiltration systems shall have appropriate positive overflow controls to prevent storage within one foot of the finished surface or grade.

(10)

All infiltration systems shall have a minimum setback of 15 feet from all residential structures. Care should be taken to prevent any seepage into subgrade structures.

(11)

Recharge systems shall be located at least 25 feet from wastewater treatment areas.

(12)

Any recharge system designed to handle runoff from any commercial or industrial parking or outside storage area shall be a minimum of 50 feet from any water supply well or any wastewater treatment area.

(13)

All infiltration systems shall be designed to infiltrate the stored volume within 48 hours.

(14)

All surface inflows shall be provided with measures to prevent the direct discharge of sediment into the infiltration system since accumulated sediment reduces stormwater storage capacity and ultimately clogs the infiltration mechanism.

(15)

Where flow across or through a pervious or impervious surface contributes to the flow to an infiltration system, no sand or other particulate matter may be applied for winter ice conditions.

(16)

The following procedures and materials shall be required during the construction of all infiltration systems and shall be noted on the stormwater and erosion control plan:

(a)

All infiltration system components shall be protected from compaction due to heavy equipment operation and/or from storage of fill or construction material.

(b)

Excavation for the infiltration system shall be performed with equipment which will not compact the bottom of the seepage bed/trench or like facility.

(c)

The bottom of the bed and/or trench shall be scarified prior to the placement of aggregate.

(d)

Only clean aggregate, free of fines, shall be allowed. AASHTO No. 1 stone is recommended.

(e)

The top and sides of all infiltration systems shall be covered with geotextile fabric. Fabric shall meet the specifications of PennDOT Publication 408, Section 735, Construction Class 1.

(f)

Perforated distribution pipes connected to centralized catch basins and/or manholes with provision for the collection of debris shall be provided in all systems. The perforated pipes shall distribute stormwater throughout the entire infiltration.

(g)

Infiltration systems shall be protected from sedimentation. All areas designated for recharge shall not receive runoff until the contributory drainage has achieved final stabilization.

(17)

All infiltration systems which service more than one lot and are considered a common facility shall have an easement provided to the Township for future access if necessary.

(18)

Prior to the end of the typical eighteen-month maintenance period required for public improvements associated with subdivision and land development plans, should any infiltration system not be functioning as designed, additional soil infiltration testing may be required and modifications shall be made to the facility based upon the results.

Detention basins.

(1)

Detention basin design criteria.

(a)

Facility design shall be in accordance with reservoir routing methods. In all cases where detention is necessary, completely developed hydrograph routing is required. The United States Department of Agriculture, Soil Conservation Service, TR-55 method shall be used. Outflow hydrographs shall be developed for discharge structures.

(b)

Facilities shall be designed so that they drain within 48 hours after the termination of the storm, unless the Township Engineer finds that downstream conditions may warrant other design criteria for stormwater release.

(c)

When basins or ponds are used, the applicant shall demonstrate that they will be designed and protected to assure that public safety is maximized and that health problems are prevented.

(d)

If the facilities remain in private ownership, the applicant shall assure proper maintenance in the form of recorded deed restrictions, bonds, or escrows, as approved by the Board of Supervisors.

(e)

If the contributing drainage area exceeds 100 acres, the greatest depth of water at maximum storage exceeds 15 feet, or the impounding capacity at maximum storage elevations exceeds 50 acre-feet, a permit is required from the PA DEP.

(2)

General basin requirements.

(a)

The design of all stormwater basins must be approved by the Township Engineer based upon their function, ease of maintenance, safety, health and welfare considerations, access, and conformance to existing landscape and surrounding uses.

(b)

Stormwater basins shall be integrated into natural contours and shall be located based upon geological, topographic, and soil conditions. When such design is impracticable, the construction of the basin design shall utilize slopes as shallow as possible to blend the structures into the existing terrain. The use of multiple retention/detention facilities, which are smaller and less intrusive on the site, is encouraged.

(c)

Stormwater basins shall be planned to avoid excessive earthmoving, tree clearance or destruction of natural amenities.

(d)

In order to reduce runoff and erosion when possible, topsoil, trees and shrubs should be preserved within and surrounding the stormwater basin, excluding the basin berm.

(e)

Any land which must be disturbed for basin construction shall be planted with cover such as, but not limited to, naturalized grass species, wetlands plants or lawn grass. The choice of cover vegetation shall be based upon the intended use of the basin, maintenance requirements, and conformity with the surroundings. Impervious surfaces are prohibited except where required for emergency spillways.

(f)

In sites where existing ponds may be used for stormwater retention or where permanent pool stormwater basins can be constructed, stormwater detention requirements may be fulfilled by these facilities, provided the design criteria are met.

(g)

The design criteria for the stormwater detention facility shall be agreed upon by the Township Engineer. Developers are encouraged to investigate all measures to reduce and detain water, for discharge at a delayed rate or groundwater recharge. All reasonable methods will be considered.

(3)

Basin construction design requirements.

(a)

The side slopes of stormwater basins shall be gently graded to permit ease of maintenance and for safety considerations. If necessary, additional basins shall be planned to achieve this standard.

[1]

All inside slopes should not be steeper than five horizontal to one vertical.

[2]

Outside slopes shall not be steeper than three horizontal to one vertical, and flatter slopes are encouraged.

[3]

Fences are not required for well-designed basins, but they are recommended for basins with side slopes of three horizontal to one vertical.

(b)

Proper stabilization shall be constructed at basin outlets. The stabilization structures should control water to: avoid erosion, reduce velocities, and direct water so as to not interfere with downslope activities.

(c)

Anti-seep collars shall be installed around the principal pipe outlet within the normal saturation zone and shall be watertight. Size and spacing of anti-seep collars shall be per a design method acceptable to the Township Engineer.

(d)

Outlet pipes shall be concrete and shall utilize O-ring watertight joints.

(e)

A key trench shall be provided for the basin berm which extends two feet into undisturbed soil and has a top width of six feet and side slopes of 1:1.

(f)

The top of the berm shall be a minimum of 10 feet wide.

(g)

A clay core shall be provided for the basin berm which has a top elevation at the water surface elevation determined in the design criteria of § 202-24E(2)(b), a minimum top width of four feet and side slopes of 1:1.

(h)

Inlet and outlet structures shall be placed as far apart as possible to ensure maximum water quality benefits, including settling, filtration, and bioactivity.

(i)

When necessary to avoid indefinite ponding of stormwater, a minimum grade of 2% across the bottom of the basin shall be maintained for all sheet flow. A minimum grade of 1% shall be maintained for all channel flow. These standards do not apply if the basin is approved to be utilized for infiltration or as a biofiltration device.

(j)

The outside top of the berm of a stormwater retention or detention basin shall be set back a minimum of 50 feet from property lines, wetlands, regulated floodplains, tops of stream banks, and structures.

(4)

Outlet structure requirements.

(a)

The outlet structure shall be a concrete riser placed on a concrete footing that extends a minimum of two feet below grade.

(b)

Trash racks/filtering screens shall be installed over the low-stage orifice(s) and may be required for other small pipes, spillways or orifices which are part of a designed outlet structure.

(c)

The flow from the fifty-year post-development to the ten-year predevelopment design criteria shall pass exclusively through the principal outlet control structure with the water surface elevation obtained when meeting the design criteria being a minimum of six feet below the crest of the emergency spillway.

(5)

Emergency spillway requirements.

(a)

Whenever possible the emergency spillway shall be constructed on undisturbed ground.

(b)

The emergency spillway must be designed to carry a one-hundred-year storm after development assuming the primary outlet is not functioning.

(c)

A minimum of six inches of freeboard shall be provided above the water surface elevation of the one-hundred-year storm when considered through the emergency spillway and the top of the berm.

(d)

Proper stabilization shall be provided for emergency spillways. Supporting calculations shall be provided.

Storm sewers.

(1)

General.

(a)

Storm sewers and appurtenances shall be required to be constructed to take surface water from the bottom of vertical grades, to lead water away from springs, to intercept water at such intervals as necessary along streets to provide safe vehicular movement, and to eliminate use of cross gutters at street intersections and elsewhere.

(b)

All pipe material, workmanship, and its installation shall conform to PennDOT specifications contained in Chapter 408, current edition.

(c)

Inlets, headwalls, manholes and other appurtenances shall be per details shown in PennDOT Standards for Roadway Construction or as approved by the Township Engineer.

(d)

Wherever practicable, storm sewers shall be located within the right-of-way of the street.

(2)

Sizing criteria.

(a)

Storm sewers shall be adequate for the anticipated runoff when the area draining to the system is fully developed as permitted by zoning.

(b)

The storm sewer system shall be capable of carrying a twenty-five-year frequency storm determined using the Rational Method and good engineering practices.

(c)

The system shall be evaluated for both gravity (Manning's Equation) and pressure (inlet/outlet control, hydraulic grade line).

(d)

The water surface elevation must be a minimum of one foot below the grate elevations of the inlet or manhole top elevations.

(e)

Excessive headwater depths shall not be created at inlets in sump, headwalls or culverts.

(f)

Provision must also be made to transport a fifty-year frequency storm to the appropriate stormwater management facility (BMP) in a manner such that surface waters will not damage property or flood streets.

(g)

Rainfall intensity shall be based upon the Field Manual of the PennDOT Storm Intensity-Duration-Frequency Charts, May 1986, or most-current revision.

(3)

Pipe/culvert requirements.

(a)

The minimum internal diameter of all pipe to be installed shall be 15 inches.

(b)

All pipes shall be either reinforced concrete or smooth bore high-density polyethylene.

(c)

The minimum pipe slope shall be 1/2 of 1%.

(d)

The maximum pipe diameter shall be 60 inches.

(e)

The minimum cover (top of pipe) shall be 18 inches.

(f)

The Manning's "n" coefficient shall be appropriate for the type of pipe specified and a minimum of 0.012 for reinforced concrete pipe.

(g)

When storm sewer is located within a street cartway, the pipe shall be bedded on six inches of 2 RC select granular material and backfilled with 2 RC select granular material placed and compacted in six-inch lifts.

(h)

When storm sewer is located in lawn areas, the pipe shall be bedded on six inches of 2 RC select granular material and backfilled with 2 RC granular material placed to a point one foot above the tope of the pipe. The remainder of the trench shall be clean fill compacted in six-inch lifts.

(i)

Provisions shall be made for watertight joints. O-ring gaskets shall be specified for reinforced concrete.

(j)

A manhole or inlet shall be provided at all horizontal deflections in the storm pipe system exceeding 5°.

(k)

All culverts or related structures conveying a watercourse with a drainage area of over 1/2 square mile shall be designed in accordance with all applicable PennDOT requirements for bridges.

(l)

Underdrains shall be used in order to eliminate soft spots or springs within/under roadways at all areas as directed by the Township Engineer.

(4)

Inlet requirements.

(a)

The storm drainage system serving the street shall be designed to collect water at the sag points of vertical curves and on the tangent of the curb radius approaching all intersections. Inlets shall not be placed on the curved portions of the curb unless unavoidable in order to be located at a low point.

(b)

All inlets must be spaced in order to accommodate the peak flow rate. The capacity and efficiency of each inlet shall be indicated in the stormwater calculations. The capacity of all C-, M-, or S-type inlets shall be determined from the latest edition of the following source:

Commonwealth of Pennsylvania

Department of Transportation

Design Manual, Part 2

Highway Design

(c)

Inlet design shall be submitted on the standard PennDOT form or equivalent form acceptable to the Township Engineer.

(d)

No inlet smaller than standard PennDOT Inlet Types C, M, and S shall be used.

(e)

Double inlets, separated by 20 feet, shall be used if adequate efficiency is not realized with standard inlets.

(f)

Inlets shall be designed and located to prevent hazards to vehicles, bicycles and pedestrians as per PennDOT requirements.

(g)

Inlet grates shall conform to PennDOT or Township standards as may be in effect at the time the design of the storm sewer is submitted.

(h)

Inlet grates shall have the following legend cast or inserted: "NO DUMPING DRAINS TO CREEK."

(5)

Manhole requirements.

(a)

Manholes shall be located on a continuous storm sewer at all abrupt changes of grade, at all locations where a transition in storm sewer pipe sizing is required, at all angle points and at all points of convergence of two or more influent storm sewer mains.

(b)

The maximum spacing of manholes on pipes of twenty-four-inch diameter shall be 300 feet and not more than 450 feet when larger size pipes are installed.

(c)

Inlets should be substituted for manholes where possible in order to facilitate inspection of the system.

(d)

Manhole frames and covers shall be good-quality cast iron. Covers shall be marked "STORM NO DUMPING DRAINS TO CREEK" and have a minimum weight of 220 pounds. Covers shall conform to PennDOT or Township standards as may be in effect at the time the design of the storm sewer is submitted.

(6)

Headwalls, endwalls, flared end sections and similar structures.

(a)

Such structures shall conform to PennDOT standards.

(b)

At-grade pipe outlets and inlets shall be provided with one of these structures.

(c)

All end treatments shall be concrete regardless of pipe material used.

(d)

Safety facilities shall be constructed, such as a debris structure utilizing a six-by-six-inch rebar grid. Such structures shall be acceptable to the Township Engineer.

(e)

Acceptable energy-dissipation devices shall be installed to bring discharge velocities down to limits specified in PA DEP's Erosion and Sedimentation Pollution Control Manual. Riprap and/or gabions may be required by the Township Engineer where erosion potential is great.

(7)

Roof drains.

(a)

Where site conditions permit, roof drains shall discharge to infiltration systems with appropriate measures such as leaf traps and cleanouts provided to prevent clogging by vegetation and debris.

(b)

Where infiltration is not possible, roof drains shall be discharged to lawn or landscaped areas and subsequently to drainage swales or to another appropriate BMP which will minimize the effects of increased runoff.

(c)

Roof drains will not be permitted to discharge directly onto parking areas, driveways, drive aisles or streets, whether in high-density residential, commercial, shopping center, industrial or low-density residential developments.

(d)

No roof drains shall discharge directly to streets or other impervious areas without approval of the Township Engineer. Only where topography conditions prohibit other design should roof drains discharge directly to the street or other impervious area, and only upon approval by the Township Engineer.

Swales.

(1)

Swales shall be sized in accordance with the criteria of § 202-24B(2).

(2)

Swales shall not be less than 1% grade. Underdrain may be required as determined by the Township Engineer in order to prevent ponding of stormwater.

(3)

Swales shall be sodded or planted as required.

(4)

Open swales will be permitted where they exist naturally and where, in the opinion of the Township Engineer, they will not interfere with public convenience or safety but in fact will provide comparable or superior drainage capabilities over piped drainage.

(5)

When located within the street right-of-way, swales shall be parabolic, not exceeding six feet in width and 1 1/2 feet in depth.

(6)

Swales shall be designed to carry the design storm with three inches of freeboard.

(7)

When curbing is installed, swales shall not be used in street rights-of-way.

(8)

Appropriate erosion control linings shall be provided based upon design requirements for stabilization during and post-construction.

(9)

Swales shall not be used to convey stormwater within a street right-of-way on slopes exceeding 8%. In those cases, storm sewer shall be used.

Sump pumps.

(1)

Where lots in a subdivision or land development are proposed to be less than one acre, or where multifamily, or other dense housing is proposed, the subdivider, developer or builder shall provide a drainage system for the collection and conveyance of sump pump discharges that will emanate from the basements of the proposed housing.

(2)

The drainage system shall run between rows of houses to collect sump pump drainage from adjacent properties.

(3)

The sump pump discharge collection system shall consist of smooth bore plastic pipe (Sc. 40 or SD 35) and have a minimum diameter of six inches.

(4)

The collection system and sump pump discharge piping shall be a minimum of three feet below grade.

(5)

The collection system shall be designed to take discharged sump pump water from adjacent houses and convey it by gravity to a positive outlet at another drainage facility, such as a catch basin, where it will be conveyed away from the residences without creating a drainage problem. Connection to other drainage facilities may not interfere with the receiving drainage facility function.

(6)

The sump pump drainage system may also be used to convey roof water, provided that the piping is sized appropriately.

(7)

Sump pump drainage systems shall be provided with cleanouts at two-hundred-foot intervals to permit unblocking the system if necessary.

(8)

A ten-foot easement shall be provided over the collection systems to provide access for maintenance of the system.

(9)

Connection of sump pumps to the collection system shall be via a wye, tee, or saddle connection. Break-in connections shall not be permitted.

Grading. All grading shall be conducted only in compliance with the following standards.

(1)

All grading shall be set back from property lines a sufficient distance to prevent any adverse effects on adjacent properties. A minimum of 10 feet is recommended.

(2)

Where grading will increase the volume, discharge, or velocity of stormwater flow toward a property line, the applicant shall install and maintain drainage facilities sufficient to prevent adverse effects on the adjoining property, designed in accordance with the standards contained elsewhere in this chapter. The construction and operation of these facilities shall not cause any adverse effects on abutting properties.

(3)

Along property lines, where grading creates an abrupt drop-off from the abutting property, in contrast to a previously existing gradual change, the applicant shall be required to install a fence or other suitable protective barrier.

(4)

Grading will not be done in such a way so as to divert water onto the property of another landowner.

(5)

Sites shall be graded to secure proper drainage away from buildings and to allow the collection of stormwater in proposed BMPs.

(6)

Minimum grades of 2% away from structures shall be required.

(7)

Grading and cut-fill operations shall be kept to a minimum to ensure conformity with the natural topography, to minimize the erosion hazard, and to adequately handle the surface runoff.

(8)

Cut-and-fill slopes shall not be steeper than 3:1, unless stabilized by a retaining wall or cribbing when handled under special conditions.

(9)

Adequate provisions shall be made to prevent surface water from damaging the cut face of excavations or the sloping surfaces of fills.

(10)

Cut and fills shall not endanger adjoining property.

(11)

Fill shall be placed and mechanically compacted to minimize sliding or erosion of the soil.

(12)

Fills shall not encroach on natural watercourses or constructed channels.

(13)

Fills placed near natural watercourses or constructed channels shall have suitable protection against erosion during periods of flooding.

(14)

During grading operations, necessary measures for dust control will be exercised.

(15)

Grading equipment will not be allowed to cross live streams. Provision will be made for the installation of culverts or bridges. The proper PA DEP permit(s) must be obtained.

(16)

Notwithstanding any provision of this chapter or any condition of the land disturbance approval, the applicant is responsible for the prevention of damage to other property, or personal injury, which may arise from the activity requiring a grading permit.

(17)

No person, firm or corporation shall modify, fill, excavate, pave, grade, or regrade land in any manner so close to a property line as to endanger or damage any adjoining street, sidewalk, alley, or any other public or private property and/or persons without supporting and protecting such property from settling, cracking, erosion, sediment, flooding, or any other physical damage or personal injury which might result. If, in the opinion of the Township Engineer, the nature of the disturbance is such as to create a hazard to life or property unless adequately safeguarded, the applicant shall construct such walls, fences, guardrails or other structures to safeguard the street, sidewalk, alley or other property and/or persons, as the Township Engineer may require.

(18)

No person, firm or corporation shall deposit or place any debris or any other material whatsoever, or cause such to be thrown or placed, in any drainage ditch or drainage structure in such a manner as to obstruct free flow.

(19)

No person shall dump, move or place any soil, trees or shrubs, bedrock or other material or divert or increase the flow of water so as to cause the same to be deposited upon, or roll, flow or wash upon or over, the premises of another without the express written consent of the owner of such premises so affected, or upon or over any public street, street improvement, road sewer, storm drain, watercourse or right-of-way or any public property.

(20)

No person, firm, or corporation shall fail to adequately maintain, in good operating order, any drainage facility on his premises. All drainage ditches, culverts, drainpipes, and drainage structures shall be kept open and free-flowing at all times.

(21)

The owner of any property on which any work has been done pursuant to a land disturbance approval granted under this chapter shall continuously maintain and repair all graded surfaces and anti-erosion devices, retaining walls, drainage structures or means and other protective devices, and ground cover, installed or completed. The Township is responsible for maintenance and repair within the right-of-way of municipal roads only.

(22)

All trees in an area of extreme grade change shall be protected with suitable tree wells, unless it is shown that complete removal of the tree is necessary to protect the public health, safety or welfare, as determined in the sole discretion of the Township Engineer or Township Supervisors. Wherever possible, trees shall be preserved and the unnecessary removal of trees shall be prevented.

(23)

A quality-control program is critical for fills; therefore, wherever fill material is to be used, the person, firm, or corporation shall be responsible for testing to determine its dry density as per ASTM D1556. The density of each layer shall be not less than 95% of maximum density as determined by ASTM D1557.

(a)

Inspection procedures shall follow the general procedure as stated in Article VIII.

(b)

Compaction test reports shall be kept on file at the site and be subject to review at all times.

(c)

The degree of compaction required shall be determined by the Township Engineer following the guidelines in this section.

Easements.

(1)

Drainage easements, a minimum width of 20 feet, shall be required along natural watercourses.

(2)

Where conditions warrant, such as in floodplains, additional width will be required for easements along natural watercourses. Such width shall be that necessary to convey the one-hundred-year floodplain.

(3)

Where stormwater or surface water will be gathered within a subdivision or land development or other site where land disturbance is proposed and where the water will be discharged or drained in volume over lands within or beyond the boundaries of the site, the subdivider, developer, or builder shall reserve or obtain easements over all lands affected, both on- and off-site. This includes detention basins, storm sewer, swales and other BMPs.

(4)

Easements shall be adequate to access and encompass the stormwater facilities (BMPs) necessary to convey the anticipated amount of runoff, as well as adequate for maintenance, repair and reconstruction of the same. Easement width shall be adequate for the right of passage over the easement by vehicles, machinery, and other equipment which may be necessary for such purposes.

(5)

The subdivider, developer, or builder shall convey, at no cost to the Township, easements to the Township upon demand, at the completion and stabilization of all the improvements.

Phasing.

(1)

When subdivisions, land developments or other land disturbances are submitted to the Township for approval in phases or sections, a complete stormwater and erosion control plan for the proposal shall first be submitted. The proposed design must include the entire tract and not a portion.

(2)

If only a section of a subdivision, land development or other land disturbance is contemplated for construction, the applicant's engineering consultant shall show the proposed handling of stormwater from the constructed section in order to prevent damage to adjacent properties in future phases. If temporary construction is required, such structures shall be included on the plan.

(3)

In the event temporary measures cannot ensure protection to adjacent properties or future phases, the main outfall line of the storm sewer shall be included as part of the construction for the currently proposed section.