The following principles of subdivision and
land development, general requirements, and minimum standards of design,
including those shown on the Horsham Township Construction Standards
(H-Standards), shall be observed by the applicant in all instances, whether
or not the proposed improvements are to be accepted by the Township.
A. All portions of a tract being subdivided shall be
taken up in lots, streets, public lands or other proposed uses so
that remnants and landlocked areas shall not be created.
B. When only a portion of a tract is being reviewed relative
to subdivision and land development, but where future subdivision
and land development is imminent, the applicant shall, subject to
approval of his plan, demonstrate that the remainder of the tract
or parcel may be subdivided or developed in conformance with the existing
zoning classification of land use in a logical and satisfactory manner.
C. Whenever a parcel of land is being subdivided for
the specific purpose of being added to an adjoining parcel of land,
prior to subdivision approval, the applicant shall provide an executed
agreement of sale between the applicant for subdivision and the owner
of the parcel to which the subdivided parcel is to annexed. Any such
subdivision must result in a lot or lots owned by the applicant and
the adjoining landowner, which shall conform in all respects to the
regulations contained in this chapter.
D. As much as possible, applicants shall preserve trees,
groves, waterways, scenic points, historic resources and other community
assets and landmarks.
E. Subdivisions and land developments shall be laid out
so as to avoid the necessity for excessive cut or fill unless specifically
warranted by terrain or location.
F. Low-lying land subject to periodic flooding shall
not be subdivided or developed for residential development or for
such other uses as may involve danger to health, safety, and general
welfare.
G. Where no public water supply is available to the subdivision
or land development, the Council shall require the subdivider, developer
or builder to obtain from the Department of Environmental Protection
and other appropriate governmental agencies with jurisdiction, certificates
of approval as to the quality and adequacy of the water supply proposed
to be utilized by the subdivider, developer or builder, and approval
of the type of construction methods and materials to be employed in
the installation of the individual water supply system.
H. Where the subdivision or land development is inaccessible to sanitary sewers, the Council shall require the landowner to obtain from the Sewage Enforcement Officer and other appropriate governmental agency with jurisdiction, certificates of approval for the sewage disposal facilities to be provided by the landowner, and approval of the construction methods and materials to be employed in the installation of the individual on-site sewage treatment system(s). Where applicable, Pennsylvania Department of Environmental Protection planning modules shall be prepared and submitted to all appropriate reviewing agencies for approval or verification of waiver of planning module requirements submitted (see Subsection
Q below).
I. Applicants shall observe the ultimate right-of-way for contiguous existing streets as prescribed by this chapter. Additional portions of the corridors for such streets shall be offered to the government agency having jurisdiction at the time the subdivision or land development is consummated. Applicable building setback lines, as defined by Chapter
230, Zoning, shall be delineated as measured from the ultimate right-of-way street line.
J. Proposed subdivision and land development shall be
coordinated with the existing nearby neighborhood so that the community
as a whole may develop harmoniously.
K. Improvement construction requirements will be completed
under specifications of the Pennsylvania Department of Transportation,
the Pennsylvania Department of Environmental Protection or other appropriate
state agency, the Montgomery County Soil and Water Conservation District,
or other appropriate agency, or under the specifications included
herein, whichever specifications shall result in the stricter interpretation
of this chapter.
L. The Township Fire Marshal shall review all proposed
applications for subdivision and/or development or construction, where
applicable, for compliance with all currently accepted fire protection
standards. All proposed facilities shall conform to such standards
as specified in the Fire Marshal's report on the proposed application.
M. All proposed applications for land development shall
be reviewed by the Township Landscape Architect for compliance with
all Township requirements related to landscaping/planting and all
other currently accepted standards. All proposed applications shall
conform to such requirements/standards as specified in the Landscape
Architect's report on the application.
N. All proposed applications for land development shall
be reviewed by the Township Lighting Consultant, for compliance with
all Township requirements and/or any other currently accepted standard
related to lighting. All proposed applications shall conform to such
requirements/standards as specified in the Lighting Consultant's report
on the application.
O. All proposed applications which may have an impact on the existing characteristics of the sound pressure levels surrounding the subjects parcel, shall, at the direction of the Township Engineer, be studied to determine the impact of such proposed operations on existing sound pressure levels. Increase in sound pressure levels, in excess of the standards set forth in Chapter
230, Zoning, of the Code of Horsham Township, will not be permitted. All noise studies shall include the monitoring and analysis of existing background noises at all applicable sensitive points along the perimeter of the subject parcel, particularly adjacent to residential areas.
P. A traffic impact study shall be required for all subdivision and/or land development applications projected to exceed 50 or more trips during the weekday morning or evening street peak hours. Traffic impact study shall be completed by a professional engineer licensed in the State of Pennsylvania, and submitted to the Township for review and approval. The traffic impact study shall be used by the Township to determine if any additional improvements beyond the scope of the proposed application will be necessary to maintain existing levels of service that would be impacted by the development. The scope and extent of such a study shall be as determined by the Township Engineer; however, the locations of the study shall not include intersections covered in Act 209 study previously conducted. A study, when conducted, shall always include an analysis of the proposed site access. Township Council may waive the traffic impact study if recommended by the Township Engineer. In either case, the applicant shall pay traffic impact fees, in accordance with Chapter
122, Impact Fees, as amended from time to time, to the Township.
Q. Appropriate Pennsylvania Department of Environmental
Protection planning modules application shall be submitted for all
proposed public and private sanitary sewer facilities with all preliminary
plan applications (or with the final plan application if preliminary
plan is not required) or verification of waiver of planning module
requirements shall be submitted. Planning modules shall meet all requirements
contained in Pennsylvania Code, Title 25, Chapter 71, Administration
of Sewer Facilities Planning Program (including "Official Plan Requirements
for Alternative Evaluation"). Such planning modules shall also meet
all procedural and content requirements of Title 25, Chapter 71, §§
71.52 and 71.53, including the requirement that they be accompanied
by the comments of the Montgomery County Health Department and the
Montgomery County Planning Commission.
R. A Pennsylvania Department of Transportation highway
occupancy permit shall be required for all proposed subdivisions and/or
land developments having any impact on any portion of the right-of-way
of a state highway or where stormwater runoff is proposed to be carried
in any way onto or across the state highway right-of-way or into the
state highway storm sewer system. A Horsham Township road opening
permit shall be required for any proposed work within Township right-of-way.
S. Emergency access driveway(s) shall be provided for
all subdivisions and land developments where only one development
access point to a public street is proposed or where otherwise deemed
appropriate by Township Council. The alignment of such access driveways
shall be as approved by the Township Engineer and shall be located
to be as short as possible and with such turning radius as is required
to provide access for all types of emergency vehicles. Accessways
shall be constructed of reinforced concrete checker blocks (backfilled
with topsoil and seeded) or other similar paver approved by the Township
Engineer, over a compacted six-inch bed of PennDOT type 2A coarse
aggregate, shall have a maximum slope of 12%, and a minimum width
of 18 feet. Such accessways shall extend from paved public cartway
to the proposed paved cartway and vehicle movement through such shall
be restricted on either end with bollard and chain or other means
acceptable to Horsham Township. All emergency access drives shall
meet the approval of the Township Fire Marshal.
T. Refuse collection. For all nonresidential and multiresidential
developments, the following shall apply:
(1) Outdoor collection stations shall be provided for
garbage and trash removal when indoor collection is not provided.
(2) Collection stations shall be located to avoid being
offensive and shall be screened from view and landscaped.
(3) Collection stations shall not be located in buffer
yards.
U. Construction of facilities. The subdivider, developer
or builder shall, where specified by the Township, construct and install,
with no expense to the Township, the streets, curbs, sidewalks, water
mains, sanitary and storm sewers, streetlights, fire hydrants, street
signs, shade trees, monuments, and other facilities and utilities
specified in this chapter. Where applicable, all proposed facilities
shall be constructed in such a manner as to be accessible to the handicapped
and shall conform to the requirements of the Americans with Disabilities
Act. Construction and installation of facilities and utilities proposed
for construction shall be subject to inspection by appropriate Township
officials during the progress of the work and the subdivider, developer
or builder shall pay for inspection.
The standards and specifications of development
in this chapter shall be used to judge the adequacy of subdivision
and/or land development proposals. Where, after application by the
landowner, it is proven that a literal application of these specifications
and standards in certain cases would work an undue hardship or be
plainly unreasonable, the Township Council may, in the exercise of
its discretion, grant such reasonable exceptions as will not be contrary
to the public health, safety, and general welfare. In reviewing applications
for such exceptions, the Township Council shall be guided by the standards
set forth in the Pennsylvania Municipalities Planning Code pertaining
to the granting of variances and special exceptions by zoning hearing
boards. The specifications of this chapter may be modified to permit
reasonable utilization of property while securing substantial conformance
with the objectives of the regulations.
The minimum requirements for improvements shall
be contained in the Pennsylvania Department of Transportation Specifications
(Publication 408 and/or Publication 72 — Road Construction
Standards) as last revised.
All new streets and cul-de-sacs and widened
portions of all existing rights-of-way, intended for public use, including,
but not limited to state and county roadways, shall be dedicated to
the Township or other governmental body having jurisdiction at the
time of dedication subject to final acceptance based on compliance
with requirements of this chapter. All proposed streets and/or driveways
associated with an approved subdivision and/or land development under
land development agreement with the Township and financially secured,
shall be completed to the extent of the pavement base (storm sewer,
curb, stone subbase and bituminous concrete base course) prior to
commencement of construction of other facilities, with the exception
of detention/retention basins, approved with the development.
A. Street system.
(1) Conformance with adopted plans. The proposed street
pattern shall be properly regulated to existing streets, to the Township
plan of streets, and to such county and state road and highway plans
as have been duly adopted by that agency.
(2) Arrangement. Streets shall be arranged in a manner
to meet with the approval of Council considered in relation to both
existing and planned streets, and located so as to allow proper development
of surrounding properties. Secondary and through highways shall be
connected with such existing streets and highways so as to form continuations
thereof. Residential streets shall be laid out to discourage their
use as secondary streets or through highways.
(3) Conformity with topography. Streets shall be adjusted
to the contour of the land so as to produce usable lots and streets
of reasonable grade, alignment and drainage.
(4) Grading. The street shall be graded to the full width
of the right-of-way and provision made for slopes beyond the right-of-way
in conformance with Township specifications.
(5) Provisions of streets for future development. Access
shall be given to all lots and portions of the tract in the subdivision
and to adjacent nonsubdivided territory. Streets giving such access
shall be improved to the limits of the subdivision. Remnants, reserve
strips and landlocked areas shall not be created.
(6) New street. New streets shall be laid out to continue
existing streets at equal or greater right-of-way and cartway width,
where such continuations are reasonable and practical.
(7) Dead-end streets. Dead-end streets are prohibited,
unless designed as cul-de-sacs or designed for access exclusively
to neighboring tracts.
(8) Street names. Continuations of existing streets shall
be known by the same name. Names for new streets shall not duplicate
or closely resemble names of existing streets. All street names are
subject to the approval of Council.
(9) Half-street. The dedication of half streets at the
edges of a new subdivision is prohibited. If circumstances render
this impracticable, adequate provision for the concurrent dedication
of the remaining half of the street, must be furnished by the subdivider,
developer or builder. When a half-street exists in an adjoining subdivision,
the remaining half shall be provided by the proposed development.
(10)
No street shall be laid out or opened which
extends to or crosses any boundary between the Township and any other
municipality except with the specific approval of the Township Council
and upon such conditions as the Township may impose.
(11)
No new street will be permitted which will cause an existing principal structure to become nonconforming to front yard requirements of Chapter
230, Zoning.
B. Street alignment.
(1) Safe stopping sight distance on horizontal and vertical
curves. Proper sight distance shall be provided with respect to both
horizontal and vertical alignments. Measured along the center line,
this shall be 500 feet for major arterial streets; 400 feet for minor
arterial streets; 250 feet for collector streets; and 200 feet for
local streets, measured at the center line and at driver's eye height
of 3.5 feet and a target height of six inches.
(2) Horizontal curves shall be used at all changes in
excess of 2°. Except where noted below, long radius curves shall
be used rather than a series of curves connected by short tangents.
Minimum radius curves at the end of long tangents will not be approved.
(a)
Curvature. The minimum radius at the center
line for horizontal curves on arterial streets shall be 300 feet;
for collector streets, 200 feet; and for local streets, 100 feet.
For the purpose of controlling speed on local streets, the maximum
radius permitted on a local street shall be 500 feet.
(b)
Tangents between curves. Except for local streets,
there shall be a tangent of at least 100 feet measured at the center
line between reverse curves. For the purpose of controlling speed
on local streets, the maximum tangent permitted on a local street
shall be 200 feet.
(c)
Horizontal curves will not be permitted on a
proposed street within 100 feet of the ultimate right-of-way of an
existing or proposed street.
(3) Vertical curves. Vertical curves shall be used at
changes in grade of more than 1%. The length of the curve shall approximate
50 feet on secondary streets and 25 feet on local streets for each
1% of change in grade. Over summits or in sumps, vertical curves shall
not produce excessive flatness in grade. The high or low point on
a vertical curve must be definitely and clearly shown.
(4) Street grades.
(a)
There shall be a minimum grade of at least 1%
on all streets.
(b)
Maximum grades. A maximum grade of 7% on major
and secondary streets and 10% on residential streets for distances
of not more than 1,500 feet. However, grades in excess of 5% shall
be avoided wherever possible. The grade shall be measured along the
center line.
(c)
Curve-grade combinations. A combination of minimum
radius horizontal curves and maximum grades will not be approved.
(d)
Street intersections. The grade within 50 feet
of any side of an intersection or the outer perimeter of a cul-de-sac
shall not exceed 3%. The grade will be measured along the curbline
of the street.
(e)
Street grading. All streets shall be graded
to the grades shown on the street profile and cross section plan submitted
and approved with the preliminary plan of subdivision and land development.
They shall be inspected and checked for accuracy by the Township Engineer.
C. Ultimate (future) right-of-way width, paving width
and curbing.
(1) Classification. All streets will be classified as
local, collector, minor arterial, or major arterial.
(a)
Local streets. shall have a minimum right-of-way
width of 50 feet. Specific streets within Horsham Township classified
as local are as specified in Subsection (C)(3) of this section. Construction
of the street, curbing and sidewalk shall be in accordance with specifications
hereinafter included in these standards.
(b)
Collector streets. shall have a minimum right-of-way
width of 60 feet. Specific streets within Horsham Township classified
as collector are as specified in Subsection (C)(3) of this section.
Construction of the street, curbing and sidewalk shall be in accordance
with specifications hereinafter included in these standards.
(c)
Minor arterial streets. shall have a minimum
right-of-way width of 80 feet. Specific streets within Horsham Township
classified as minor arterial are as specified in Subsection (C)(3)
of this section. Construction of the street, curbing and sidewalk
shall be in accordance with specifications hereinafter included in
these standards.
(d)
Major arterial streets shall have a minimum
right-of-way of 100 feet. Specific streets within Horsham Township
classified as major arterial are as specified in Subsection (C)(3)
of this section. Construction of the street, curbing and sidewalk
shall be in accordance with specifications hereinafter included in
these standards.
(e)
Cul-de-sac streets shall have a minimum right-of-way
width of 50 feet. Specific streets within Horsham Township classified
as cul-de-sac are as specified in Subsection (C)(3) of this section.
Construction of the street, curbing and sidewalk shall be in accordance
with specifications hereinafter included in these standards.
[1]
A cul-de-sac will not be approved when a through
street is practicable. A cul-de-sac shall not be more than 500 feet
in length. A cul-de-sac must be a side street and not be the permanent
culmination of another street to form a four-way intersection. A cul-de-sac
shall have a circular turnaround with a minimum right-of-way radius
of 70 feet and an outer paving radius of 60 feet.
[2]
A cul-de-sac permanently terminated will not
be approved when a through street is practicable. The subdivider shall
have the burden of showing the impracticability of the through street
in order to justify a cul-de-sac.
[3]
A cul-de-sac permanently or temporarily exceeding
500 feet in length may be approved by Council if conditions of the
land so warrant. The minimum length of a cul-de-sac shall be 250 feet.
[4]
Where it is proposed that a road be constructed
to an abutting property line with the intention that such a road will
be extended onto the adjoining property at a future date, the temporarily
terminated cul-de-sac shall be constructed the same as one permanently
terminated; including the right-of-way (or temporary cul-de-sac easement)
width and outer paving radius.
[5]
A snow removal easement shall be provided at
the rear of all cul-de-sac bulbs for the piling and storage of plowed
snow by the Township or other snow removal entity. Such an easement
shall as much as possible be centered on the projection of the cartway
center line, into the bulb right-of-way. The easement shall have a
minimum width of 15 feet measured from the right-of-way line and minimum
arc length of 50 feet or as otherwise deemed necessary by the Township
to provide adequate snow storage area. Except for required sidewalks,
nothing shall be permitted to be placed or planted within the easement
including but not limited to driveways, mailboxes, street trees or
other landscaping, and lights. Snow removal easements shall be owned
and maintained by individual lot owners or other Township approved
entity and removal of snow from required sidewalks within the easement
shall be the responsibility of the individual lot owners or other
approved maintenance entity. Such easements shall be described on
the record plan with ownership and maintenance responsibilities defined.
[6]
The Township Engineer shall review commercial
and industrial cul-de-sacs for adequacy. When deemed necessary by
Township Council, additional cartway and/or right-of-way radius may
be required.
(2) Right-of-way. Where a proposed subdivision and/or
land development abuts or contains an existing public street or road
having a right-of-way width less than would be required if said street
or road were created under this chapter, sufficient additional width
for right-of-way shall be provided and dedicated to meet the foregoing
standards. Additional right-of-way may be required by Council to promote
public safety and convenience when required by special conditions.
(3) Specifications and categories.
(a)
The minimum widths of paving and the requirements
for curbing and sidewalk shall not be less than those of an existing
street of which the new street is to be a continuation, nor less than
the standards provided below. Where a subdivision and/or land development
fronts on an existing street, curb and sidewalk, where required, shall
be constructed and the existing paved cartway shall be extended to
the required curbline. Where a subdivision and/or land development
abuts an existing street, drainage improvements shall be made to the
existing street, where deemed necessary by Council. Additionally,
existing cartways shall be reconstructed where necessary to establish
the minimum construction standards of this chapter. Where reconstruction
is not required, leveling and overlay of the cartway with ID-2 binder
and wearing course material may be required to improve the cartway
surface. Additional cartway widths may be required by Council to promote
public safety and convenience when required by special conditions.
Construction of any such widening, curb, sidewalk, or drainage improvements
shall be as specified herein (Horsham Construction Standards) or as
directed by the Township Engineer.
Type of Street
|
Ultimate (Future) Right-of-Way Width
(feet)
|
Paving Width
(feet)
|
Curbing
|
Sidewalk
|
---|
Major Arterial
|
100
|
52 (or more as may be required)
|
Required
|
Required
|
Minor Arterial
|
80
|
40
|
Required
|
Required
|
Collector
|
60
|
40
|
Required
|
Required
|
Local
|
50
|
30
|
Required
|
Required
|
Cul-de-sac
|
50
|
30*
|
Required
|
Required
|
* Note: All cul-de-sac bulbs shall have a minimum-paving
radius of 60 feet.
|
(b)
The types of streets as herein set forth above
shall include specific streets as listed below:
[1]
Major arterial. This category shall include
the following streets:
|
Horsham Road
|
Blair Mill Road
|
|
Welsh Road
|
Easton Road
|
|
Bethlehem Pike
|
County Line Road
|
[2]
Minor arterial. This category shall include
the following streets:
|
Norristown Road
|
Lower State Road
|
|
Limekiln Pike
|
Dresher Road
|
[3]
Collector. This category shall include the following
streets:
|
Meetinghouse Road
|
Park Road
|
Witmer Road
|
|
Maple Avenue
|
Davis Grove Road
|
Prudential Road
|
|
Mann Road
|
Chestnut Lane
|
Rock Road
|
|
Jarrett Road
|
New Road
|
Gibraltar Road
|
|
Babylon Road
|
McKean Road
|
Precision Road
|
|
Moreland Road
|
Herman Road
|
Sheehy Drive
|
|
Tennis Avenue
|
Cedar Hill Road
|
Electronic Drive
|
|
Butler Pike
|
Privet Road
|
|
|
Keith Valley Road
|
|
|
[4]
Local and cul-de-sac. This category shall include
streets used primarily as the principal means of access to adjacent
properties and shall include all streets not otherwise categorized,
as appropriate.
D. Street paving. All street paving must conform to the
specifications incorporated in this section of the standards and Horsham
Township Construction Standards and be approved by the Township Engineer prior to acceptance
by Council. All grades, horizontal curves, vertical curves, intersections,
sight distances, and tangents shall conform to the requirements established
by this chapter and shall be subject to the approval of the Township
Engineer.
(1) Subgrade. The bottom of the excavation and the top
of the fill between the outer limits of the paving or base course,
when completed, will be known as the subgrade and shall conform to
the lines, grades and cross sections given. The subgrade for macadam
paving shall conform to the established line, grade and cross section
as approved by Council. The subgrade shall be solidly compacted for
a firm and unyielding state by rolling with a minimum of ten-ton power
roller. Unstable areas shall be removed and replace with suitable
fill and then rerolled as required to provide a uniform even, unyielding
surface.
(a)
Construction methods. After the excavation or
rough grading has been performed and all drains have been constructed,
the subgrade will be fine graded and shaped to the proper cross section.
It shall be brought to a firm unyielding surface by rolling the entire
area with an approved roller having a metal weight of not less than
10 tons. Solid rock, boulders, soft clay and all spongy materials,
which will not consolidate under the roller, shall be removed from
the subgrade to a depth to be determined by the Township Engineer
or other person designated by Council. The space shall be filled with
suitable material from the excavation and the subgrade rerolled until
it presents a smooth and firm surface of the proper shape and cross
section. Crown board and straight edge shall be used for checking
road and street construction. Maximum deviation shall not exceed 1/4
inch. It shall be the responsibility of the developer to verify required
stability of subgrade through compaction testing suitable to the Township
Engineer.
(2) Stone subbase. The subbase shall be PennDOT type 2A
crushed aggregate or other material approved by Township Council.
(a)
Type 2A crushed aggregate. Crushed aggregate
shall have a compacted thickness of six inches for streets of all
classifications, unless otherwise approved by Council.
(b)
Materials. Materials meeting the requirements
as specified in Sections 350.2 and 703.2 of the Pennsylvania Department
of Transportation Publication 408, latest revision, shall be used.
(c)
Construction methods. Construction and installation
of type 2A crushed aggregate subbase shall comply with Pennsylvania
Department of Transportation, Publication 408, latest revision, Section
350.3.
(3) Paving base course. The base course shall be "Superpave
Asphalt Mixture Design, 25 MM Mix, PG 64-22, HMA Base Course, 3.0
to 10.0 Million ESALS," or other material approved by Township Council.
[Amended 8-13-2014 by Ord. No. 2014-3]
(a)
Superpave Asphalt Mixture Design, 25 MM Mix,
PG 64-22, HMA Base Course, 3.0 to 10.0 Million ESALS. "Superpave Asphalt
Mixture Design, 25 MM Mix, PG 64-22, HMA Base Course, 3.0 to 10.0
Million ESALS" shall have a compressed thickness after compaction
of 4 1/2 for local and cul-de-sac classified roads/streets and
six inches for all other classified roads/streets, unless otherwise
approved by Council.
(b)
Materials. Materials meeting the requirements
as specified in Section 305.2 of the Pennsylvania Department of Transportation
Publication 408, latest revision, shall be used.
(c)
Construction methods. Construction and installation
of Superpave Asphalt Mixture Design, 25 MM Mix, PG 64-22, HMA Base
Course, 3.0 to 10.0 Million ESALS shall comply with Pennsylvania Department
of Transportation, Publication 408, latest revision, Sections 401.3
and 403.3, with the following additions:
[1]
Base course shall not be placed on surfaces
that are wet or at a temperature of 35° F. or lower, or when air
temperature is 35° F. or lower.
[2]
If the proposed base course thickness is greater
than five inches in compacted depth, it shall be placed in two or
more lifts of approximately equal depth, with no layer more than 2 1/2
inches. Base course shall be placed in layers of not less than four
inches in depth when the air temperature is less than 40° F.
(4) Superpave Asphalt Mixture Design, 9.5 MM Mix, HMA
Wearing Course, 3.0 to 10.0 Million ESALS, SRL-H. This surface course
shall consist a wearing course, of hot-mixed, hot-laid asphalitic
concrete, constructed on a prepared bituminous base course. The bituminous
surface course shall have a total thickness, after final compaction
of 1 1/2 inches or as approved by the Township. All street pavement
cross sections, except where superelevated for curves, will be a minimum
slope from the center of the road to the gutter of a minimum of 1/4
inch per foot to a maximum of 5/16 inch per foot, unless otherwise
approved by Council.
[Amended 8-13-2014 by Ord. No. 2014-3]
(a)
Materials. The materials shall conform to the
requirements as given in Section 420 of the Pennsylvania Department
of Transportation Specifications 408, latest revision.
(b)
Construction methods. The wearing course shall
be Superpave Asphalt Mixture Design, 9.5 MM Mix, HMA Wearing Course,
3.0 to 10.0 Million ESALS, SRL-H, as specified in Pennsylvania Department
of Transportation Publication 408, latest revision, and shall be applied
in strict accordance with Publication Section 420.3. No visible moisture
shall be present prior to the laying of each course. Road surface
and air temperature shall be a minimum of 40° Fahrenheit or greater
prior to laying of the bituminous surface. The air temperature shall
also be rising. Prior to placement of surface course, all unsuitable
materials from the surface of the existing pavement base course, including
loose and foreign material and excess joint sealer and crack filler,
shall be removed. Existing vertical surfaces (of curbs, gutters, structures,
etc.) shall be painted with a uniform bituminous material, as specified
in Pennsylvania Department of Transportation Publication 408, latest
revision, Section 401.3(f). When specified by the Township Engineer,
scratch or leveling courses shall be applied to wheel ruts and other
local, small depressions, in order to raise these areas to the level
of the surrounding uniform pavement. Scratch or leveling shall be
completed prior to placement of wearing course. Prior to placement
of wearing course, a tack coat conforming to Publication 408 Section
460.3 shall be applied to the bituminous base course (or binder course
where approved) when directed by the Township Engineer.
(c)
Horsham Township shall require delivery slips
for all materials used in the construction of streets.
(5) Underdrain. When directed by the Township Engineer
or where the finished roadway grade is within one foot of the seasonal
high water table as designated for site-specific soils type as designated
in the Soil Survey for Montgomery County, a combination storm sewer
and underdrain shall be place along the curbline of all new roads/streets,
in accordance with the construction standards defined in the "Horsham
Township Construction Standards" adopted as part of this chapter. An acceptable alternative to the combination storm sewer
and underdrain would be a six-inch perforated, corrugated polyethylene
pipe (or other approved by the Township Engineer).
(6) Shoulder. Supporting shoulder shall be constructed
on all sections of roads where a base course or pavement is approved
to be constructed without other permanent support along the sides
(such as concrete curb or granite/Belgian block curb, etc.). All shoulder
shall be thoroughly compacted and graded to provide drainage from
the macadam surface.
(a)
Construction methods. Where concrete curbing
is not to be constructed, shoulders are to be constructed adjacent
to the paving of the proposed road. The width and type of construction,
grade, and construction methods of these shoulders shall be as depicted
in the Horsham Township Construction Standards or as otherwise approved
by the Township Engineer or other person designated by Council.
E. Repair and maintenance of existing streets and roadways.
All public streets utilized by a developer for access to a site during
construction shall be maintained and repaired, as needed, by the developer
at their own expense, in accordance with Horsham Township Standards.
Where road improvements or utility work is required within the public
cartway of an existing street, the following maintenance/repair work
shall be required:
(1) Where the existing road along the frontage of the
parcel being developed is being widened, the remainder of the existing
cartway not being widened shall be milled and overlaid from the physical
center line to the face of new curb or edge of cartway (along the
entire frontage of the parcel). If the existing road surface is severely
damage by trenching and construction vehicle traffic, the existing
road pavement shall be entirely removed and replaced in accordance
with Township Standards.
(2) Where utilities are being installed in existing roads,
the cartway shall be milled and overlaid from the physical center
line to the face of curb or edge of cartway. This work shall be completed
over the entire extent of the utility work area where utilities are
only being installed in 1/2 of the road cartway. If utilities are
being installed on both sides of the road, the entire road cartway
shall be milled and overlaid in accordance with Township Standards,
along the entire extent of the utility work area.
(3) Where utility installation is not consistent with
that described above, the exact extent of road maintenance and repair
shall be determined by Council with the recommendation of the Township
Engineer.
(4) Where no utility work or widening is being completed
along an existing road, however, the existing road is being damaged
by construction vehicle traffic to a particular development site,
at the discretion of the Township Engineer, appropriate road repairs
shall be completed by the developer, at their expense, to restore
the road to its predevelopment condition. Such work shall include
but not be limited to milling, pavement replacement, and overlay across
a portion of or the entire road damage by the construction vehicle
traffic.
F. Street intersections.
(1) Number of intersections. No more than two streets
shall cross at the same point. When existing streets intersect at
odd angles, or have more than four approaches, the subdivider, developer
or builder shall be required to make corrective changes to eliminate
the odd angle or reduce the number of approaches to the intersection
by curving the lesser street.
(2) Minimum angle of intersection. Ninety-degree-angle
intersections shall be used when local or cul-de-sac streets connect
to arterial or collector streets. Intersection of all proposed streets
shall be made at ninety-degree angles.
(3) Center lines. Where center lines of streets are proposed
to open onto opposite sides of an existing or proposed street within
175 feet of each others center lines, they shall be made to coincide
by curving the street or streets of lesser classification.
(4) Primary thoroughfares. Wherever practicable, intersections
with arterial streets shall be kept to a minimum and shall be located
at least 1,200 feet apart.
(5) Intersection sight distance. Sight distance at proposed
driveway and/or street intersections shall conform to the requirements
of Pennsylvania Code, Title 67, Chapter 441 (and as stated in the
Horsham Construction Standards, adopted as part of this chapter), as from time to time amended. If necessary to achieve
the minimum required sight distance, the applicant shall be responsible
for altering on-site and off-site existing features along the sight
lines defined in Chapter 441. If such features are located outside
of the legal right-of-way of the fronting street or road, the applicant
shall be responsible for obtaining temporary construction and permanent
sight distance easements over the area requiring modification. In
all cases, permanent sight distance easements shall be established
over all off-site area, outside of the legal right-of-way and along
the sight lines of the proposed driveway or street intersection, if
sight lines cross adjacent private property. The record plan of the
subdivision and/or land development shall contain appropriate notations
defining ownership and maintenance within the area of any such easement.
The applicant as well as the entity ultimately responsible for maintenance
of the land development (homeowners' association, etc.) shall be responsible
for perpetual maintenance of the easement area in order to preserve
the required sight distance. All improvements to be completed within
such easement areas shall be completed in accordance with the requirements
of this chapter. The extent of improvements along the required sight
lines shall be verified by the applicant and approved by the Township
Engineer. Proof of required sight distance easement and/or temporary
construction easements shall be submitted to Horsham Township prior
to plan approval.
(6) Maximum grade. Maximum grade within any intersection
shall not exceed 1%, and approaches to an intersection shall follow
a straight horizontal course for 100 feet.
(7) Approach grades. All approaches to an intersection
shall not exceed 3% for a distance of 50 feet measured from the nearest
right-of-way line of the intersecting street.
(8) Radii of pavement and right-of-way at intersections.
Street intersections shall be rounded with tangential arcs at pavement
edge (curbline) and right-of-way as listed below. Where two streets
of different right-of-way widths intersect, the radii of curvature
for the widest street shall apply.
|
Type of Street
|
Minimum Radius of Curve at Intersection
of Pavement Edge or Curblines
(in feet)
|
Minimum Radius of Curve at Intersection
of Right-of-Way Lines
(in feet)
|
---|
|
Major arterial
|
40
(or more as may be required)
|
20
(or more as may be required)
|
|
Minor arterial and collector
|
35
|
20
|
|
Local
|
25
|
15
|
|
Cul-de-sac
|
25
|
15
|
G. Roadside barriers. Roadside barriers and guide rail shall be required in accordance with PennDOT Design Manual, Part
2, Highway Design, Chapter 12 (Publication No. 13), latest revision. Construction and materials shall be in accordance with applicable PennDOT Road Construction Standards (Publication No. 72).
H. Traffic control. Vehicular traffic control in work
zone areas on and along streets open to the public shall be in strict
accordance to requirements of PennDOT Publication 203, Work Zone Traffic
Control (67 Pa. Code, Chapter 203).
I. "P-loop" streets (loop streets from a single access
point) shall have an entrance leg not exceeding 500 feet. The loop
of a "P-loop" shall have a street length not exceeding 3,000 feet.
Within a Residential Golf Course Community,
all permitted structures and/or uses may be served by private streets.
Such streets shall be designed and constructed in accordance with
the requirements of this section. Private streets shall not be dedicated
to the Township; nor does the Township assume the responsibility for
their maintenance.
A. Street system. Private streets within a Residential Golf Course Community shall comply with §
198-31A, with the exception that continuations of existing streets shall not be required. All such streets shall be designed to provide access suitable for fire, ambulance and other emergency vehicles. The owner may limit nonemergency and nonmunicipal access onto private streets.
B. Street alignment. Private streets within a Residential Golf Course Community shall comply with the requirements for residential streets as set forth in §
198-31B.
C. Right-of-way width, paving width and curbing.
(1) Classification. Private streets within a Residential
Golf Course Community shall be classified and governed in accordance
with the following provisions:
(a)
Private connector streets. Private connector
streets shall be those private streets providing vehicular access
between existing public streets and areas within a Residential Golf
Course Community. On-street parking shall be prohibited, and driveways
serving individual dwelling units shall not be permitted to access
directly onto private connector streets. The minimum allowable right-of-way
width shall be 50 feet and the minimum allowable cartway width shall
be 24 feet for two-way streets and 18 feet for one-way streets. A
private connector street providing only stabilized emergency access
to an existing public street shall be designed to provide adequate
circulation for anticipated nonemergency traffic.
(b)
Private residential streets. private residential streets shall be those private streets providing vehicular access between private connector streets and residential areas of a Residential Golf Course Community, and vehicular access within such areas. Private residential streets shall not access directly onto existing arterial or collector streets except as may be required for emergency vehicular access. Such streets shall comply with §
198-33E.
[Amended 10-9-2002 by Ord. No. 4019]
A. Purposes. In order to protect the health, safety,
and general welfare of Horsham Township residents by protecting the
surface and groundwater of Horsham Township the developer shall construct
and install drainage and stormwater management practices, or shall
modify the design of proposed improvements, to achieve the following
purposes:
(1) Prevent erosion and to satisfactorily carry off or
detain and control the rate of release of surface waters. Prior to
finish grading of a development site and final overlay of streets,
roads, and driveways, temporary measures, acceptable to the Township,
shall be taken to ensure that all runoff intended to be intercepted
and collected by an inlet or other catch facility, will be collected.
Proposed land development plans shall specifically defines means to
accomplish this.
(2) Encourage all runoff control measures to percolate
the stormwater into the ground to aid in the recharge of ground waters.
(3) Carry surface water to the nearest adequate street,
storm drain, detention basin, and natural watercourse or drainage
facility.
(4) Take surface water from the bottom of vertical grades,
to lead water away from springs, and to avoid the use of cross gutters
at street intersections and elsewhere.
(5) No development shall be permitted that generates more runoff in the postdevelopment condition than the site in its natural condition for the same frequency storm (one-year through one-hundred-year), unless more strict standards are specified in Chapter
190, Stormwater Management, adopted previously.
(6) Not only handle the anticipated peak discharge from
the property being subdivided or developed in accordance with the
applicable release rate as set forth in this chapter, but also the
existing runoff being contributed from all land at a higher elevation
in the same watershed. The future use of undeveloped areas upstream
shall be taken into account in the calculation of pipe sizes for storm
sewer system designs. The capacity and maximum anticipated present
flow of the body or system receiving the proposed system(s) discharge
shall be calculated to verify its capability of receiving any additional
flow caused by the development or subdivision. The runoff from any
proposed development shall be subject to an evaluation that includes
the anticipated runoff from other existing or proposed developments
with the same watershed. Stormwater management facilities designed
to serve more than one property or development in the same watershed
are encouraged; consultation with the Township is required prior to
design of such facilities.
(7) Maintain and improve the existing water quality of
receiving waterways including streams, rivers, ponds, lakes, and impoundments.
(8) Maintain the adequacy of the natural stream channels.
Accelerated bank erosion shall be prevented by controlling the rate
and velocity of runoff discharge to these watercourses, so as to avoid
increasing occurrence of stream bank overflow.
(9) Preserve the adequacy of existing culverts and bridges
by suppressing the new flood peaks created by new land development.
(10)
If in the course of preparing or reviewing the
stormwater management plan, the Township determines that off-site
improvements are necessary to satisfactorily handle the stormwater
from the proposed development the developer shall be responsible for
those off-site improvements.
(11)
Maintain the existing predevelopment water balance
in watersheds and subwatersheds containing first-order streams and
other sensitive streams in Horsham Township, and to work to restore
natural hydrologic functions and habitat wherever possible throughout
the stream system.
(12)
Maintain the predevelopment volume of groundwater
recharge.
(13)
Maintain predevelopment runoff volumes, and
prevent a significant increase in surface runoff volumes, predevelopment
to postdevelopment, which could worsen flooding downstream in the
watershed, enlarge floodplains, erode streambanks, and create other
flood-related health-welfare-property losses.
(14)
Maintain or reduce predevelopment peak rates
of discharge, site-by-site, for specified reference storms so flooding
at adjacent downstream sites does not worsen, and to work to reduce
peak runoff rates to natural level.
(15)
Manage stormwater impacts close to the runoff
source which require a minimum of structures and maximize reliance
on natural processes.
(16)
Minimize non-point source pollutant loadings
to ground and surface waters throughout Horsham Township.
(17)
Minimize impacts on stream temperatures.
B. General requirements.
(1) Stormwater management plan. All major and minor subdivisions
and land developments that disturb greater than 5,000 square feet
shall submit a stormwater management plan and report. The stormwater
management plan and report shall contain, but not be limited to, the
following:
(a)
A suitable map of the total watershed (a United
States Geological Survey quadrangle map is sufficient) with predevelopment
(existing) and postdevelopment (proposed) areas outlined.
(b)
Suitable maps and drawings showing all existing
drainage facilities affecting the subject property.
(c)
A plan of the proposed stormwater drainage system
attributable to the subdivision or land development.
(d)
The design computations for the stormwater drainage
systems, including storm drain pipes, inlets, runoff control measures
and culverts, drainage channels, and other best management practices.
(e)
A grading plan, including all areas of disturbance,
of the subject subdivision or land development.
(f)
A plan of the erosion and sedimentation procedures
to be utilized.
(g)
A plan of the stormwater drainage system, showing
all pipes, swales, channels, structures, detention basins, other best
management practices shall be submitted as part of the stormwater
management plan. The drainage areas into each inlet or structure must
be delineated on the plan of the storm drainage system.
(h)
A maintenance plan consistent with the requirements of Subsection
I(3).
(i)
Delineate the pathways of all concentrated flow
(i.e., flow other than overland sheet flow).
(2) Permanent stormwater management standards. All minor
and major subdivisions and land developments that disturb greater
than 5,000 s.f. shall provide stormwater controls which are designed
and constructed to provide groundwater recharge, water quality treatment,
and peak flow attenuation in conformance with the following:
(a)
Recharge requirement. In order to preserve predevelopment
levels of groundwater recharge and minimize the increased volumes
of stormwater discharging into local streams, structural best management
practices shall be implemented on-site consistent with the following:
[1]
Structural best management practices including,
but not limited to, permeable pavement, infiltration trenches, and
seepage beds shall be used to mitigate for the decreased levels of
groundwater recharge and the increased volumes of stormwater caused
by land disturbance, and the creation of impervious surface.
[2]
Based upon the proposed area of land disturbance,
including impervious areas, and the underlying hydrologic soil grouping,
the following formula shall be used to determine the minimum volume
of water (acre-feet) to be intercepted and retained to infiltrate
on-site:
|
Recharge Volume (acre-feet) = [ (A * 0.38) +
(B * 0.25) + (C * 0.13) + (D * 0.06) ]/12
|
|
Where:
|
|
A
|
=
|
Disturbed acreage underlain by hydrologic soil
group "A"
|
|
B
|
=
|
Disturbed acreage underlain by hydrologic soil
group "B"
|
|
C
|
=
|
Disturbed acreage underlain by hydrologic soil
group "C"
|
|
D
|
=
|
Disturbed acreage underlain by hydrologic soil
group "D"
|
|
Example: Existing 15 acre parcel
with six acres of disturbance on "B" soils and three acres of disturbance
on "C" soils.
|
|
Recharge Volume = [ (0 * 0.38) + (6 * 0.25)
+ (3 * 0.13) + (0 * 0.06) / 12 = 0.158 acre feet
|
|
Therefore, structural best management practices
need to be designed and constructed on site to intercept and retain
a minimum of 0.158 acre-feet of stormwater.
|
(b)
Recharge alternatives.
[1]
Horsham Township Council may determine, upon
recommendation of the Township Engineer, that use of best management
practices to satisfy the recharge requirement is not possible due
to site configuration, existing soil, bedrock, water table, or other
site conditions, or may result in ground water contamination due to
existing or proposed site activities.
[2]
In place of the recharge requirement, the peak rate standards of Subsection
B(2)(d)[1], below, shall be modified so that the postdevelopment peak rate of discharge from the site must be equal to or less than 75% of the predevelopment peak rate for all storms up to and including the ten-year storm.
(c)
Water quality requirement. In order to reduce
the water quality impacts of stormwater on receiving streams, nonstructural
(vegetative) best management practices and dry basin discharge controls
shall be utilized on-site consistent with the following:
[1]
Nonstructural (vegetated) best management practices,
including but not limited to bioretention areas, filter strips, grass
swales, and riparian buffers, shall be used to mitigate the impacts
of stormwater from impervious areas on water quality. Based upon the
total site area and the underlying hydrologic soil grouping, the following
formula shall be used to determine the minimum percentage of impervious
area to be directed to and/or drained by nonstructural best management
practices:
|
Percent Area = (A * 38) + (B * 25) + (C * 13)
+ (D * 6)
|
|
Where:
|
|
A
|
=
|
Percentage of site underlain by hydrologic soil
group "A"/100
|
|
B
|
=
|
Percentage of site underlain by hydrologic soil
group "B"/100
|
|
C
|
=
|
Percentage of site underlain by hydrologic soil
group "C"/100
|
|
D
|
=
|
Percentage of site underlain by hydrologic soil
group "D"/100
|
|
Example: Existing 15 acre parcel
with 40% of the site underlain by "B" soils, 20% underlain by "C"
soils, and 40% of the site underlain by "D" soils.
|
|
Percent Area = (0 * 38) + (0.40 * 25) + (0.20
* 13) + (0.40 *6) = 15%
|
|
Therefore, a minimum of 15% of the site's proposed
impervious area shall be directed to and/or drained by nonstructural
best management practices.
|
[2]
The volume of stormwater for the one-year, twenty-four-hour
design storm (rainfall depth equals 2.7 inches) generated by areas
of impervious surface not directed to structural or nonstructural
best management practices shall be controlled so that the one-year
storm takes 24 hours to drain from the facility from a point where
the maximum volume of water captured by the facility for the one-year
storm is achieved (i.e., the maximum water surface elevation achieved
in the facility).
(d)
Peak flow attenuation. Following compliance
with the recharge and water quality requirements, peak flow from the
proposed development shall be attenuated consistent with the following
requirements:
[1]
The peak rate of stormwater discharge from the site for the design storms noted in Subsection
D(2) shall not exceed the peak discharge from the site of the same storm before proposed development:
[2]
To reduce the need for large wet and/or dry ponds to satisfy the peak flow attenuation requirements, other innovative best management practices located close to the source of the runoff generation (rooftop storage, bioretention, infiltration trenches) shall be considered, including a combination of best management practices (i.e., rooftop storage draining into an infiltration trench having overflow conveyed by a grass swale). In addition, the impact of structural and nonstructural best management practices implemented to meet the requirements of Subsection
B(2)(a) may be considered when designing the facility(s) to satisfy the peak flow attenuation requirement to reflect the volume of runoff being infiltrated and/or increased times of concentration.
(3) Watercourses, streams, or intermittent streams.
(a)
Whenever a watercourse, stream, or intermittent
stream is located within a development site, it shall remain open
in its natural state and location and shall not be piped. It shall
be the responsibility of the developer to stabilize eroded or erodible
stream banks that can cause sedimentation in downstream waterways.
(b)
The Township may require a developer to provide
a permanent easement along any watercourse located within or along
the boundary of any property being subdivided or developed. The purpose
of any such watercourse easement shall be for maintenance of the channel
of any watercourse; the terms of the easement shall prohibit excavation,
the placing of fill or structures, and any alterations that may adversely
affect the watercourse. The easement shall conform to the line of
the watercourse and shall be of sufficient width to protect the natural
drainage system which shall be calculated using a one-hundred-year
storm event, however, in no case shall the easement be less than 30
feet in width. The developer will retain the easement until such time
as one of the following is accomplished:
[1]
If an easement acceptable to the municipality
is established, the maintenance shall then be the responsibility of
the individual lot owners over whose property the easement passes.
For land developments the maintenance shall then be the responsibility
of the owner. The record plan shall contain description of such easement(s)
and notation indicating the maintenance responsibility.
[2]
A homeowners' association or other approved
legal entity, approved by the Township, assumes responsibility for
the maintenance of the development, including the watercourse easement.
(c)
Horsham Township will not accept dedication
of watercourse easements, however, shall, upon satisfactory installation
of improvements as specified in a land development agreement with
Horsham Township, maintain and repair only the structural improvements
within the easement, if any, such as: piping; inlets; headwalls/endwalls;
and energy dissipation structures or facilities. The Township will
not be responsible for any other repair/maintenance within the easement
such as: lawn/ground cover maintenance; vermin control; removal of
obstructions and accumulated sediment or vegetation; removal of litter
or garbage; repair of erosion; and restoration of vegetation. The
record plan and development agreement for the approved land development
shall contain a provision permitting access to such easement(s), at
any reasonable time, for inspection and/or emergency repair/maintenance
by Horsham Township or its designee, of all facilities deemed critical
to the public's welfare. In the event the lot owner or homeowners'
association responsible for maintenance fails to honor the responsibility
set forth herein, in any manner, Horsham Township shall have the right
of entry upon and within the area of the easement to undertake any
required corrective or maintenance effort. The total cost of such,
including administrative, engineering, and legal costs for enforcement,
may be imposed upon the responsible party as determined by Horsham
Township. Failure to remedy all associated costs described above,
may be subject of the imposition of a lien by the Township against
the owner(s) in question, in the same manner as the Township might
otherwise be empowered by law to assess or impose a lien against a
property for municipal improvements.
(4) The existing points/patterns and character of natural
drainage discharge onto and off of adjacent property shall not be
altered without the approval of the affected adjoining property owners.
Verification of such approval must be obtained in writing and a copy
filed with Horsham Township. Approval of plans by the Township does
not authorize or sanction drainage affecting adjoining properties.
(5) When directed by the Township Engineer and/or where
the finished roadway grade is within one foot of the seasonal high
water table as designated for the site-specific soils type as designated
by the Soil Survey for Montgomery County, storm sewer shall be designed
as a combination storm sewer and underdrain. An acceptable alternative
to the combination storm sewer and underdrain would be a six-inch
perforated corrugated polyethylene pipe. As much as practical, all
storm sewer, as required, shall be placed in the right-of-way, parallel
to the roadway. When located in undedicated land, storm sewer shall
be placed within an easement not less than 30 feet in width or as
otherwise approved by the Township Engineer.
(6) Where applicable, stormwater management facilities
or programs shall comply with the requirements of Chapter 102 (Erosion
Control), Chapter 105 (Dam Safety and Waterway Management), and Chapter
106 (Floodplain Management) of Pennsylvania Code, Title 25, Rules
and Regulations of the Department of Environmental Protection.
(7) A Pennsylvania Department of Transportation highway
occupancy permit is required if stormwater runoff is to be carried
in any way onto state Highway right-of-way or into the state Highway
storm drainage system. The Township shall defer final approval of
stormwater management facilities until the developer secures a highway
occupancy permit, as applicable.
(8) The developer may be required to participate in off-site storm drainage improvements in the drainage basin within which the proposed development is located. The specific contribution/ improvements required shall be as specified by the Township Council and as specified in Article
VIII of this chapter.
(9) Stormwater roof drains from nonresidential and multiresidential
buildings (where applicable) shall not discharge water directly onto
a sidewalk or a street and shall be constructed to discharge overland
prior to eventual discharge into a storm sewer system and/or detention
basin.
(10)
Water originating from other than natural sources,
such as air-conditioning units, sump pumps, or other dry weather flow,
wherever practical and possible, shall be discharged overland towards
natural watercourses on the property. These facilities shall not discharge
water under the sidewalk, through the curb, into the gutter.
(11)
All proposed subdivision and land developments within Little Neshaminy Creek Watershed shall comply with the requirements of Horsham Township Ordinance 221, Little Neshaminy Creek Watershed Stormwater Management Ordinance, previously adopted by the Township in conjunction with Pennsylvania Storm Water Management Act 167 (copy of the ordinance is
included as an attachment to this chapter).
(12)
Storm drainage facilities and appurtenances
shall be so designed and provided as to minimize erosion in swales,
watercourse channels, and at all points of discharge.
(13)
Where applicable, stormwater management plans/reports
shall document downstream effects of detention and delayed or altered
storm peaks, including necessary steps to avoid downstream combination
of peak flows.
(14)
All stormwater runoff and floodplain calculations
and stormwater management facilities design shall be prepared by a
professional engineer licensed in the State of Pennsylvania.
(15)
Flood protection. No stormwater runoff or natural
drainage shall be so diverted as to overload existing drainage systems,
or create flooding or the need for additional drainage structures
on other private properties or public lands, without proper and approved
provisions being made for resolving flooding conditions.
(16)
Low point drainage. The developer shall grade
and install all necessary drainage facilities to insure drainage of
all low points on subdivided or developed land areas (except in areas
of protected "wetlands").
(17)
No person, corporation, or other such entity
shall block, impede the flow of, alter, construct any structure, or
deposit any material or thing, or perform any work that will affect
the normal runoff onto or off of an adjacent parcel.
(18)
All plans wherein a sump pump or basement drain
is proposed to be installed shall provide for discharge of the sump
pump/drain overland to a natural watercourse, drainage swale, stormwater
easement, or storm sewer system.
(19)
Where stormwater or surface water will be gathered
within the subdivision or land development and discharged or drained
in volume over lands within or beyond the boundaries of the subdivision
or land development, the subdivider, developer, or builder shall reserve
or obtain easements over all lands affected. The easements shall be
adequate for such discharge of drainage and for carrying off of such
water and for the maintenance, repair, and reconstruction of the same,
including the right of passage over, including vehicles, machinery
and other equipment for such purposes, and which shall be sufficient
width for such passage and work. If requested by the Township, the
subdivider, developer, or builder shall convey, at no cost, the easements
to the Township. Otherwise, all such easements shall be owned and
maintained by individual lot owner(s) or another approved entity.
Ownership and maintenance responsibilities shall be noted on the record
plan and agreements for such shall be as approved by the Township
Solicitor.
C. Stormwater runoff peak rate requirements: Little Neshaminy
Creek Watershed.
(1) General. In order to implement the provisions of this chapter and to maintain consistency with the approved Little Neshaminy Creek Watershed Stormwater Management Plan (Pennsylvania Stormwater Management Act 167), the Township is hereby divided into stormwater runoff peak rate districts which are consistent with the Little Neshaminy Creek Watershed Stormwater Management Plan. The boundaries of the stormwater runoff peak rate districts are shown on an official Stormwater Runoff Peak Rate Map, included as part of Ordinance No. 221 (
included as an attachment to this chapter). This ordinance is also available for inspection at the
Township Administration Building.
(2) Release rate districts. These watershed areas require that the postdevelopment peak rate of stormwater runoff be controlled to the stated percentage of the predevelopment peak rate of stormwater runoff for the range of design storms set forth in Subsection
D(2) of this section (the one-year, twenty-four-hour storm through the one-hundred-year, twenty-four-hour storm) in order to protect downstream watershed areas. For the purposes of implementing the provisions of the Little Neshaminy Creek Watershed Stormwater Management Plan, portions of the Township have been subdivided into subareas. The delineation of subareas by number is shown on an official Subbasin Map that is available for inspection at the Township Administration Building. The release rate districts and their release rate controls are as follows:
(a)
Seventy-five-percent release rate district:
postdevelopment runoff peak rate shall be controlled to 75% of the
predevelopment runoff peak rate for Subarea 84.
(b)
One-hundred-percent release rate district: postdevelopment
runoff peak rate shall be controlled to 100% of the predevelopment
runoff peak rate, i.e., conventional "post- to predevelopment" peak
rate attenuation, for Subareas 22, 25-34, 44, 46, 49-59, 61-79, 82-83,
and all other areas of the Township not tributary to the Little Neshaminy
Creek.
(c)
Provisional direct discharge: one-hundred-percent
release rate district. Within this district, development sites shall
be permitted to discharge directly to the Little Neshaminy Creek main
channel or indirectly to the main channel through an existing stormwater
drainage system (storm sewer or tributary), provided such a system
has adequate capacity to convey the increased peak flows or will be
provided with improvements to furnish the required capacity for a
one-hundred-year design storm. Applicable Subarea: 45.
(3) Water quality requirements. The design storm for meeting the water quality requirement of Chapter
190, Stormwater Management, shall be based on the one-year return period, twenty-four-hour storm, as defined by Chapter
190, having a rainfall depth of 2.7 inches. The water quality requirement of infiltration, wet pond, and created wetland systems shall be based on retention of the postdevelopment runoff volume resulting from the one-year, twenty-four-hour storm. First flush or dual-purpose detention systems shall be considered the minimum best management practices for satisfying the water quality requirements of this chapter. First flush or dual-purpose detention systems shall detain the postdevelopment runoff from the one-year, twenty-four-hour storm so that it is released over a minimum period of 25 hours.
(4) In performing the stormwater calculations, all those
areas to be disturbed during construction and subsequently returned
to open space will be assumed to be reduced one hydrologic soil group
category level for postdevelopment runoff calculations (i.e., hydrologic
soil group B is reduced to hydrologic soil group C and so forth).
(5) Meadow in good condition shall be used in predevelopment
runoff calculations for all areas including areas of existing cultivation
and/or impervious surface.
(6) The Rational Method of stormwater calculation shall be limited to watersheds of 10 acres or less. The "Soil Cover Complex" method of stormwater calculation, as outlined in Subsection
D(1) and
(2), shall be used for all watersheds greater than 10 acres.
(7) All other provisions of Chapter
190, Stormwater Management, are to be addressed with any plan submission.
D. Requirements for runoff calculations outside Little
Neshaminy Creek Watershed:
(1) To calculate the potential increase in runoff and
peak flow rate resulting from a proposed site development, the "Soil
Cover Complex" method shall be used, as outlined in Urban Hydrology
for Small Watersheds, U.S. Department of Agriculture, Technical Release
55 (NTIS PB87-101580), with specific attention given to antecedent
moisture conditions, flood routing, time of concentration, and peak
discharge specifications included therein and in Hydrology National
Engineering Handbook, Section 4, both by the U.S. Department of Agriculture,
Natural Resources Conservation Service. Mathematical analyses described
in Computer Program for Project Formulation - Hydrology (S.C.S. Technical
Release 20, 1983) may also be utilized. Upon consultation with the
Township Engineer, designers of stormwater management facilities may
utilize the Modified Rational Method for calculation of runoff hydrographs
for small watersheds. The application of the Modified Rational Method
shall be in accordance with procedures set forth in the Pennsylvania
Department of Environmental Protection publication, "Recommended Hydrologic
Procedures for Computing Urban Runoff from Small Watersheds in Pennsylvania"
and shall be limited to watersheds of 10 acres or less.
(2) All calculations consistent with this chapter using
the "Soil Cover Complex" method shall use the appropriate design rainfall
depths for the various return period storms presented below. A type
II storm distribution, with twenty-four-hour duration, shall be used
as the basis for hydrograph generation. Antecedent moisture condition
shall be assumed as the average condition. When developing the necessary
"Soil Cover Complex" calculations or otherwise approved calculation
method, a predeveloped condition (existing condition) of farm field,
undeveloped land and/or disturbed earth, shall be considered "meadow
in good condition" for modeling purposes, unless the natural ground
cover would result in a lower curve number or Modified Rational runoff
coefficient ("C"). Runoff curve numbers (CN) for both existing and
proposed conditions to be used in the "Soil Cover Complex" method
shall be obtained from Urban Hydrology for Small Watersheds, TR-55
(as amended or replaced).
|
Return Period
|
24-Hour Rainfall Depth
(inches)
|
---|
|
1-year
|
2.7
|
|
2-year
|
3.3
|
|
5-year
|
4.2
|
|
10-year
|
5.0
|
|
25-year
|
5.8
|
|
50-year
|
6.4
|
|
100-year
|
7.2
|
(3) In performing the stormwater calculations, all those
areas to be disturbed during construction and subsequently returned
to open space will be assumed to be reduced one hydrologic soil group
category level for postdevelopment runoff calculations (i.e., hydrologic
soil group B is reduced to hydrologic soil group C and so forth).
(4) If approved by the Township Engineer, all calculations using the Modified Rational Method shall use rainfall intensities consistent with appropriate times of concentration for overland flow and return periods from the design storm curves (storm intensity- duration-frequency curves) for Region 5, found in the Pennsylvania Department of Transportation Design Manual Part
2, latest revision. Time of concentration (Tc) shall be defined as the interval of time required for water from the most remote portion of the drainage area to reach the point in question (design point). The Tc shall be representative of the developed area, i.e., a long Tc shall not be used if the majority of the proposed development is within close proximity to the detention facility. Time of concentration for overland flow shall be calculated using the methodology presented in Chapter 3 of Urban Hydrology for Small Watersheds, TR-55 (as amended or replaced). Times of concentration for channel and pipe flow shall be computed using Manning's equation. Runoff coefficients ("C") for existing and proposed conditions, for use in the Modified Rational Method, shall be obtained from the Pennsylvania Department of Transportation Publication, Design Manual Part
2, or upon consultation with the Township Engineer, may be obtained from the Pennsylvania Department of Environmental Protection publication, "Recommended Hydrologic Procedures for Computing Urban Runoff from Small Watersheds in Pennsylvania."
(5) In calculating the time of concentration (for either
analysis method) for a watershed, the maximum length of sheet flow
over paved or unpaved surfaces shall be 50 feet to 100 feet. The theoretical
maximum length of 300 feet shall be utilized only in unique situations
(as approved by the Township Engineer) such as uniformly sloped, smoothly
paved parking areas.
(6) Meadow in good condition shall be used in predevelopment
runoff calculations for all areas including areas of existing cultivation
and/or impervious surface.
E. Storm sewers and drainageways.
(1) General provisions. All storm drains and drainage
facilities such as gutters, catch basins, bridges, inlets, and culverts
shall be installed and the land graded for adequate drainage as shown
on the grading plan submitted and approved with the final plan. Construction
of these facilities shall generally conform with PennDOT Specifications
Publication 408, latest version.
(2) When required. Storm drains and appurtenances shall
be required to be constructed by the developer to take surface water
from the bottom of vertical grades to lead water away from springs,
and to avoid excessive use of cross gutters at street intersections
and elsewhere.
(a)
Open watercourses 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 of
piped drainage. Where necessary, stream corridor improvements, including
rock stabilization and gabions, shall be performed.
(b)
When submitting a plan for approval involving
the construction of storm drainage facilities the designer's computations
shall be submitted in duplicate to facilitate the checking of design.
(c)
Design of storm drainage facilities shall be
completed in accordance with accepted engineering practices subject
to approval by the Township Engineer.
(d)
Where practical, inlets shall be situated in
grassed swales or depressions.
(3) Unnatural drainage. Wherever construction stops or
concentrates the natural flow of storm drainage in such a way to affect
adjoining properties, approval of the owners shall be obtained in
writing and a copy filed with the Township. Approval of plans by the
Horsham Township does not authorize or sanction drainage affecting
adjoining properties.
(4) Design criteria.
(a)
Open channels should have a parabolic or trapezoidal
cross-section in compliance with accepted engineering practices.
(b)
Permissible channel velocities, slopes, and
cover shall be in accordance with the Natural Resource Conservation
Service Engineering Field Manual, Chapter 7, "Grassed Waterways and
Outlets."
(c)
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, with
approval of the Department of Environmental Protection (DEP) and the
Montgomery County Conservation District.
(d)
Acceptable energy dissipation devices shall
be installed to bring discharge velocities down to limits specified
in the DEP Erosion and Sediment Pollution Control Program Manual,
latest edition.
(e)
Rip-rapping and/or gabions may be required by
the Township Engineer where erosion potential is great.
F. Storm sewer design.
(1) Design flow rate.
(a)
The storm sewer system shall be designed to
carry the one hundred-year peak flow rate. The design one-hundred-year
peak flow rate into each inlet shall be indicated in storm sewer calculations
and the drainage area to each inlet shall be indicated on the stormwater
management plan. The one-hundred-year flow rate shall be determined
by the Rational Method formula Q = CIA, where:
|
Q
|
=
|
Peak runoff rate measured in cubic feet per
second (cfs).
|
|
C
|
=
|
Runoff coefficient. The coefficient of stormwater
runoff includes many variables, such as ground slope, ground cover,
shape of drainage area, etc.
|
|
I
|
=
|
Intensity. Average rainfall intensity in inches
per hour for a time equal to the time of concentration.
|
|
A
|
=
|
Area. Drainage area in acres.
|
(b)
Appropriate values for the rainfall intensity
can be found in the Pennsylvania Department of Transportation Design
Manual, Part 2. Appropriate values for the runoff coefficient shall
be as presented below:
|
Rational Method Runoff Coefficients ("C")
for the Design of Storm Sewer
|
|
Description of Area
|
Runoff Coefficient ("C")
|
|
Residential
|
|
|
2-acre lots
|
0.40
|
|
1-acre lots
|
0.45
|
|
1/2-acre lots
|
0.50
|
|
1/4-acre lots
|
0.60
|
|
Townhouses, multifamily
|
0.70
|
|
Commercial
|
0.75
|
|
Industrial
|
0.80
|
|
Parks, cemeteries
|
0.35
|
|
Meadow
|
0.30
|
|
Unimproved (forest, brush, meadow, mixed)
|
0.25
|
(c)
Where the above table is not applicable, the
following factors may be used for smaller drainage areas:
|
Rational Method Runoff Coefficients ("C")
for the Design of Storm Sewer (Smaller
Watersheds)
|
|
Description of Area
|
Runoff Coefficient ("C")
|
|
Roofs and all other impervious surfaces
|
0.95
|
|
Grass (or other similar pervious areas)
|
0.35
|
|
Forest
|
0.25
|
(d)
More specific runoff coefficients, as stated
in the Pennsylvania Department of Transportation Design Manual, Part
2, or as stated in the Pennsylvania Department of Environmental Protection
publication "Recommended Hydrologic Procedures for Computing Urban
Runoff from Small Watersheds in Pennsylvania" may be used upon consultation
with the Township Engineer.
(2) Consideration shall be given to future land use changes
in the drainage area in selecting the "C" coefficient. For drainage
areas containing several different types of ground cover, a weighted
value of "C" shall be used. In no case shall a weighted value of "C"
be less than 0.45 for an area to be changed from its natural state.
(3) In determining the peak flow rate to individual storm sewer inlets (or other collection structures) the time of concentration method [as referenced in Subsection
D(4) and
(5)] shall be used for inlet drainage areas in excess of 1.25 acres, unless otherwise specified by the Township Engineer, and a five-minute time of concentration shall be used for all other drainage areas, unless otherwise approved by the Township Engineer.
(4) In determining the required design flow rate through
a storm sewer piping system, a five-minute time of concentration (storm
duration) shall be used if the five-minute time of concentration does
not result in a maximum expected discharge that exceeds the capacity
of a thirty-inch-diameter pipe (or equivalent flow area of 4.9 square
feet).
(5) In determining the required design flow rate through a storm sewer piping system, if a five-minute time of concentration (storm duration) results in a pipe size exceeding a thirty-inch-diameter pipe (or equivalent flow area of 4.9 square feet), the time of concentration approach [as defined in Subsection
D(4)] shall be used in determining storm duration.
(6) In determining the required design flow rate through
a storm sewer piping system, if a five-minute time of concentration
results in a pipe size exceeding 30 inches, within any run of pipe,
the time of concentration approach may be used for sizing of pipes
from that point on, by adjusting the time of concentration.
G. Required stormwater management facilities.
(1) Storm sewer easements.
(a)
Easements shall be a minimum of 30 feet in width
and shall be provided in undedicated land to accommodate required
storm sewer facilities and drainage swales. Such easements shall be
offered for dedication to Horsham Township and shall be provided where
storm sewer, drainage swales, culverts, or other structures traverse,
enter or discharge onto private property. On private property, the
property owner shall maintain ground cover and landscaping within
the easement. The Township shall not maintain and/or repair any improvements
within that easement unless stormwater runoff from public roads or
public park land crosses through the easement. If stormwater runoff
from public roads or public lands crosses through the easement, the
Township shall, upon satisfactory installation of improvements as
specified in a land development agreement with Horsham Township, maintain
and repair only the structural improvements within the easement, if
any, such as: piping; inlets; stormwater manholes; headwalls/endwalls;
and energy dissipation structures or facilities. Horsham Township
will not be responsible for any other repair/maintenance within the
easement such as: lawn/ground cover maintenance; vermin control; removal
of obstructions from drainage swales; removal of accumulated sediment
or vegetation from drainage swales; removal of litter or garbage;
repair of erosion; and restoration of vegetation/ground cover.
(b)
The record plan and development agreement for
the approved land development shall define easement ownership, maintenance
responsibilities, and access. Specifically, the record plan shall
contain a provision permitting access to such easement(s), at any
reasonable time, for inspection and/or emergency repair/maintenance,
by Horsham Township or its designee, of all facilities deemed critical
to public welfare. In the event the lot owner or homeowners' association
fails to honor their maintenance responsibilities set forth herein,
in any manner, Horsham Township shall have the right of entry upon
and within the area of the easement to undertake any required corrective
or maintenance effort. The total cost of such, including administrative,
engineering, and legal costs for enforcement, may be imposed upon
the responsible party as determined by Horsham Township. Failure to
remedy all associated costs described above, may be subject of the
imposition of a lien by the Township against the owner(s) in question,
in the same manner as the Township might otherwise be empowered by
law to assess or impose a lien against a property for municipal improvements.
(2) Piping.
(a)
The minimum diameter of all storm sewer piping
shall be 18 inches (or other with an equivalent flow area of 1.76
square feet) including detention basin barrel pipes. Piping shall
be laid on a four-inch-minimum bed of PennDOT type 2A coarse aggregate
and shall be designed with a slope such that a minimum full-flow velocity
of two feet per second will be attained; however, the slope shall
not be less than 0.50%. No pipe shall exceed a slope that will permit
full-flow velocity in excess of 15 feet per second. Storm sewer piping
shall be reinforced concrete pipe (RCP), however, in areas that are
not to be dedicated for public use, either smooth-bore, high density
corrugated polyethylene (CPP) or aluminum corrugated pipe shall be
permitted. All outlet pipes through detention basin and retention
basin berms shall be reinforced concrete pipes with watertight "O-ring"
joints (O-ring RCP).
(b)
The capacity of all pipes shall, as a minimum,
shall provide the required carrying capacity as determined by the
U.S. Department of Commerce, Hydraulic Design Series No. 5, Hydraulic
Design of Highway Culverts. Where pressure flow is anticipated in
storm sewer pipes (non-open channel flow), the applicant's designer
shall be required to calculate the elevation of the hydraulic grade
line through the storm sewer system. Wherever the hydraulic grade
line elevation exceeds the pipe crown elevation for the design flow,
pipes with watertight joints must be specified.
(c)
The top of storm sewer pipes shall be at least
six inches below the subgrade elevation of bituminous pavements, except
for reinforced concrete pipe which may be at subgrade elevation provided
the applicant verifies the pipe will withstand current PennDOT HS-25
loading standards. For pipes in pervious areas, the top of pipe elevation
shall be a minimum of one foot below the finished surface.
(3) Overflow system. An overflow system shall be provided
to carry all bypass flow and/or flow in excess of storm sewer design
capacity, to the detention basin (or other approved outlet point)
when the capacity of the storm sewer system is exceeded. Stormwater
runoff will not be permitted to surcharge from storm sewer structures.
(4) Manholes.
(a)
Storm sewer manholes shall be spaced as necessitated
by the proposed piping alignment, however, in no case shall manhole
spacing exceed 300 feet, except between manholes connected by pipe
with a diameter of 48 inches or greater, where spacing shall then
not exceed 450 feet.
(b)
Manhole castings and covers shall conform to
requirements of Pennsylvania Department of Transportation Publications
72 and 408, latest revisions. Manhole covers shall have the word "STORM"
cast in two-inch-high letters on the top of the cover.
(5) Inlets.
(a)
Storm sewer inlets shall be spaced in accordance
with this chapter; however, in no case shall inlet spacing exceed
250 feet, except between inlets connected by pipe with a diameter
of 48 inches or greater, where spacing shall then not exceed 450 feet.
(b)
Any inlet to be utilized in a storm sewer system
shall conform to the design standards of Pennsylvania Department of
Transportation (PennDOT) Publications 408 and 72 (Road Construction
Standards). Specifically, inlets to be utilized within a public right-of-way
shall be Type "C" with the "Alternate" inlet concrete top unit (which
includes a Type "C" structural steel frame) and Type "M" with standard
concrete top unit. All other inlets shall be Type "C" and "M" with
standard concrete top units. All inlet grates shall be "bicycle safe"
structural steel.
(c)
At street intersections, inlets shall be placed
in the tangent and not in the curved portion of the curbing. The gutter
adjacent to and immediately upgrade from the inlet shall be so warped
as to direct the water into the inlet. Inlets shall be required on
the upslope side of all approaches to an intersection.
(d)
The crowns of all pipes tying into an inlet
or manhole shall be set at equal elevations. A minimum of two inches
shall be provided between the inlet pipe invert elevation and the
invert elevation of the outlet pipe.
(e)
The capacity of inlets shall be based on a maximum
surface flow to the inlet of four CFS (cubic feet per second). The
maximum flow to inlets located in low points of paved areas (such
as sag vertical curves) shall include the overland flow directed to
the inlet, as well as the cumulative bypass surface runoff from inlets
upstream. The bypass runoff from each upstream inlet shall be calculated
using inlet efficiency curves (or other analysis method approved by
the Township Engineer) found in the Pennsylvania Department of Transportation
Design Manual, Part 2, latest revision. An inlet at a low point of
a paved area may be designed to accept a maximum of six cubic feet
per second (CFS). Type "M" inlets shall be designed to accept a maximum
surface flow of six CFS, unless otherwise approved by the Township
Engineer. Double inlets will not be permitted where additional pipe
and inlets can be placed upstream to intercept the excessive surface
flow. Under special circumstances, a maximum of 12 CFS shall be permitted
to be collected by an inlet located in an isolated pervious area provided
the designer can prove such an inlet would not cause stormwater to
accumulate on any adjacent public or private property, outside of
the associated proposed storm sewer easement, and that the depth of
the accumulated stormwater would not exceed 12 inches. Double four-foot
or six-foot inlets separated by 20 linear feet of pipe shall be required
if adequate efficiency is not realized with four-foot inlets.
(f)
Inlet spacing in paved areas shall be arranged so that a minimum of 80% of the gutter flow tributary to the inlet will be captured. The designer shall be required to verify that bypass surface runoff from the one-hundred-year design storm will enter the storm sewer piping system at some point, prior to discharge into a detention basin or other approved outlet point. Inlets shall be spaced so that the accumulation of surface bypass runoff and surface runoff tributary to an individual inlet will not exceed other design requirement specified in this chapter. Inlet capacity shall be based on inlet efficiency curves provided in Pennsylvania Department of Transportation, Design Manual, Part
2.
(g)
A minimum of one foot of freeboard, between
the inlet grate and the design flow elevation, shall be provided in
all storm sewer systems (inlets and manholes).
(h)
Inlet castings, together with their covers or
gratings, shall conform to PennDOT or Horsham Township Standards,
as may be in effect at the time the design of the sewer is submitted.
(i)
All inlets shall be stenciled by the developer
to indicate that "No Dumping Allowed — This inlet flows to .
. . Creek," or other approved wording by Horsham Township. Specifications
for stenciling are to be provided by Horsham Township.
(j)
Inlets in paved areas shall incorporate grit
chambers.
(6) Headwalls and endwalls.
(a)
An endwall shall be provided at the end of all
pipe runs. Headwalls shall be provided at the beginning of all pipe
runs. A headwall shall also be required (instead of an inlet) where
calculated surface flows exceed the requirements for inlets in pervious
areas. Headwalls/endwalls with a height greater than three feet may
be required to have a safety fence or guiderail if so determined by
the Township Engineer. Rock apron (rip-rap) or other approved velocity
dissipation device shall be placed at all pipe outlets (endwalls)
to reduce flow velocity and prevent erosion.
(b)
All headwalls and endwalls shall be stenciled
by the developer to indicate that "No Dumping Allowed — This
inlet flows to . . . Creek," or other approved wording by Horsham
Township. Specifications for stenciling are to be provided by Horsham
Township.
(7) Curb and roadside swales.
(a)
Roadside swales adjacent to shoulders. When
swales are provided in cut areas, the water shall not encroach upon
the roadway area during a twenty-five-year design storm of five-minute
duration. Storm sewer inlets shall be provided to control the roadway
encroachment and water velocity.
(b)
Shoulder swales (in cut areas - no roadside
swale). Water flowing in the shoulder shall not encroach more than
2/3 the shoulder width during a twenty-five-year design storm of five-minute
duration (time of concentration). Storm sewer inlets shall be provided
to control the shoulder encroachment and water velocity.
(c)
Curbed sections. The maximum encroachment of
runoff on the roadway pavement shall not exceed 1/2 of the traveled
lane during a twenty-five-year design storm of five-minute duration.
Inlets shall be provided to control the encroachment of water on the
traveled lane.
(d)
The maximum velocity of flow as determined by
Manning's equation shall not exceed the allowable velocities as shown
in the following table for the specific type of material, unless otherwise
approved by the Township Engineer and the Montgomery County Conservation
District or as otherwise updated in the Pennsylvania Department of
Environmental Protection, Bureau of Soil and Water Conservation Publication,
Erosion and Sediment Control Program Manual, latest revision:
|
Material
|
Allowable Velocity
[feet per second (fps)]
|
---|
|
Well-established grass on good soil:
|
|
|
|
Short pliant bladed grass
|
4.0 to 5.0
|
|
|
Bunch grass - soil exposed
|
2.0 to 3.0
|
|
|
Stiff-stemmed grass
|
3.0 to 4.0
|
|
Earth without vegetation:
|
|
|
|
Fine sand or silt
|
1.0
|
|
|
Ordinary firm loam
|
2.0 to 3.0
|
|
|
Stiff clay
|
3.0 to 5.0
|
|
|
Clay and gravel
|
4.0 to 5.0
|
|
|
Coarse gravel
|
4.0 to 5.0
|
|
|
Soft shale
|
5.0 to 6.0
|
|
Shoulders:
|
|
|
|
Earth (as defined above)
|
|
|
|
Stabilized
|
6.0
|
|
|
Paved
|
10.0 to 15.0
|
(8) Bridges, culverts, and drainage channels.
(a)
Bridges and culverts shall be designed and constructed
to meet current Pennsylvania Department of Transportation construction
and loading standards (HS-25 loading standards). They shall be constructed
to the full width of the right-of-way or to an adequate dimension
to accommodate special grade conditions. Approval of the Pennsylvania
Department of Environmental Protection is required for all improvements
in and along all waters of the commonwealth. The applicant shall provide
verification of Department of Environmental Protection approval for
all such proposed bridges and culverts.
(b)
Approval of the Pennsylvania Department of Environmental
Protection is required for all improvements in and along waters of
the commonwealth. Where applicable, stormwater management facilities
or programs shall comply with the requirements of Chapter 102 (Erosion
Control), Chapter 105 (Dam Safety and Waterway Management), and Chapter
106 (Floodplain Management) of Pennsylvania Code, Title 25, Rules
and Regulations of the Department of Environmental Protection.
(c)
All bridges, culverts, and drainage channels
shall be designed to convey a flow rate equal to a one-hundred-year,
twenty-four-hour storm as defined by the U.S. Department of Agriculture,
Soil Conservation Service, Technical Release No. 55. All bridges and
culverts shall be designed to pass the one-hundred-year design storm
without increasing the extent and depth of the one-hundred-year floodplain.
(d)
Drainage channels shall be designed to convey
the design discharge at a stable, nonerosive velocity. Channel linings
that are assumed in the design must be established before the channel
is utilized for its stated objective. Diversions or alternate channel
linings may be necessary to provide channel conditions in the field
to match design assumptions. If the design channel lining cannot be
developed before the design discharge is introduced, then the designer
must check the stability of the channel assuming a bare earth condition.
(e)
Maximum channel velocities for vegetated and
rock-lined channels shall be as set forth in the Pennsylvania Department
of Environmental Protection, Bureau of Soil and Water Conservation
Publication, Erosion and Sediment Control Program Manual, latest revision.
(f)
The outfall of drainage channels shall be stable
under the design discharge. Energy dissipaters (rock lining/rip rap)
shall be utilized to return drainage channel discharge to a stable
velocity.
(g)
Any vegetated drainage channel requiring mowing
of the vegetation shall have a maximum grade (side slopes) of four
horizontal to one vertical (4:1 — 25%) on those areas to be
mowed.
(9) Stormwater detention/retention basins.
(a)
The design of stormwater basins shall be based on the criteria set forth in the latest revision of Urban Hydrology for Small Watersheds, U.S. Department of Agriculture, Soil Conservation Service, Technical Release 55 (NTIS PB87-101580) and following mathematical analyses described in Computer Program for Project Formulation - Hydrology (S.C.S. Technical Release 20, 1983). Upon consultation with the Township Engineer, designers of stormwater management basins may utilize the Modified Rational Method for calculation of runoff hydrographs for watersheds. The application of the Modified Rational Method shall be in accordance with procedures set forth in the Pennsylvania Department of Environmental Protection publication, "Recommended Hydrologic Procedures for Computing Urban Runoff from Small Watersheds in Pennsylvania," and shall be limited to watersheds of 10 acres or less. Rainfall depths for the Soil Conservation Service (TR-55) method shall be as stated in Subsection
D(2) of this section. Rainfall intensities for the Modified Rational Method (if approved for use by the Township Engineer) shall be consistent with appropriate times of concentration for overland flow and return periods as provided in the design storm curves (storm intensity-duration-frequency curves) for Region 5, found in the Pennsylvania Department of Transportation Design Manual, Part
2, latest revision. As much as possible, design of stormwater detention/retention basins shall incorporate best management practices as defined by Chapter
190, Stormwater Management, of the Code of Horsham Township.
(b)
Detention areas shall be designed so that the total rate of runoff from the entire site, after complete development, will not exceed the specified percentage of the total predeveloped runoff rate [specified in Subsections
A(5),
C and
D of this section] from the entire site. Individual points of concentrated runoff discharge from the site may be designed for up to a 100% release rate so long as the total runoff from the entire site, after development, is controlled to the applicable release rate.
(c)
Discharge piping from detention areas shall be designed to control the rate of runoff as referred to in Subsection
G(9)(a) and
(b) above, for a one-year through one-hundred-year frequency design storm.
(d)
If permanent ponds (retention basin) are proposed,
the developer shall demonstrate that such ponds are designed to protect
the public's health and safety.
(e)
Detention or retention basin easements, ownership,
and maintenance. Prior to granting of final approval of any subdivision
or land development plan, the developer shall provide written assurance,
satisfactory to the Township, that the detention or retention basin
and associated stormwater management facilities will be properly maintained.
Such assurances shall be in a form to act as a covenant that will
run with the land, and shall provide Township maintenance at the cost
of the landowner in case of default, and further provide for assessment
of costs and penalties in case of default. If all or a portion of
the facilities are on property which will be conveyed to an individual,
homeowners' association or any other eventual owner, the guarantees
must be in such a form that they will carry through to the new owners.
Horsham Township will not accept dedication or maintenance responsibilities
for any detention or retention basin or similar facility located on
private grounds, unless otherwise approved by Township Council.
[1]
When a private entity (such as a homeowners'
association) retains ownership of any stormwater management facility,
such entity shall be responsible for maintenance of the facility.
In such case, approval of the stormwater management facility plans
shall be conditioned upon the private entity agreeing to be responsible
for all maintenance of the stormwater management facility. This agreement
shall be in writing, shall be in recordable form and shall, in addition
to any other terms deemed necessary by the Township, contain a provision
permitting access to such facilities deemed critical to the public
welfare, for inspection at any reasonable time by Horsham Township
or its designee.
[2]
When any stormwater management facility is located
on an individual lot, and when maintenance thereof is the responsibility
of that landowner, a description of the facility or systems and the
terms of the required maintenance shall be incorporated on a plat
of the property. The plat shall be recorded with the Montgomery County
Recorder of Deeds within 90 days following Township approval. The
plat of the property shall also contain a provision permitting access
to such facilities deemed critical to public welfare, for inspection
at any reasonable time by Horsham Township or its designee. The Township
may also require as a condition of approval that any deed conveying
any interest in such lot contain language indicating that the conveyance
is subject to an express covenant by the grantee that the grantee
will maintain the stormwater management facility.
[3]
Upon presentation of proper credentials, duly
authorized representatives of Horsham Township may enter at any reasonable
time upon any property within the Township to investigate or to ascertain
the condition of the subject property with regard to any matter regulated
by this chapter.
[4]
The failure of any person, individual lot owner
or private entity to properly maintain any stormwater management facility
shall be construed to be a violation of this section and is declared
to be a public nuisance, subjecting the violator to any and all penalties
provided by law. Specifically, in the event the entity responsible
for maintenance fails to honor those responsibilities set forth herein,
in any manner, Horsham Township shall have the right of entry upon
the area of such facilities to undertake any required corrective or
maintenance effort. The total cost of such, including administrative,
engineering, and legal costs for enforcement, may be imposed upon
the responsible party as determined by Horsham Township. Failure to
remedy all associated costs described above may be subject of the
imposition of a lien by the Township against the owner(s) in question,
in the same manner as the Township might otherwise be empowered by
law to assess or impose a lien against a property for municipal improvements
(f)
When basins are provided, they shall be designed
to utilize the natural contours of the land whenever possible. When
such design is not practical, the construction of the basin shall
utilize slopes as flat as possible to blend the structure into the
terrain. Detention basins shall be designed to facilitate regular
maintenance, mowing and periodic de-silting and reseeding. In residential
developments, shallow broad basins shall be provided for recreational
use.
(g)
Except with the one-year design storm, basins
shall be designed so that they return to normal conditions within
approximately 12 hours after the termination of the storm, unless
the Township Engineer finds that downstream conditions may warrant
other design criteria for stormwater release.
(h)
Emergency overflow facilities shall be provided
for basins to handle runoff in excess of design flows, or in the event
the outlet structure becomes blocked and passes no flow.
(i)
If the land of the proposed subdivision or land
development will be conveyed to two or more separate owners, the developer
shall provide written assurance and deed restrictions to the Township
that the owners will properly maintain the basin(s).
(j)
Basins shall not be located within floodplains;
nor within areas of floodplain soils with the exception that areas
of alluvial soils may be utilized, if approved by the Pennsylvania
Department of Environmental Protection and Army Corps of Engineers
(where applicable), if proof is accepted that the area is not subject
to flooding.
(k)
The use of regional basins to combine and eliminate
numerous smaller basins is encouraged. Consultation with the Township
is required prior to design of a regional basin.
(l)
Landscaping and planting in and around the perimeter
of basins shall be provided. It shall be aesthetically pleasing and
compatible with surrounding land uses, and require minimum maintenance.
Proposed planting shall also be in accordance with the provisions
of this chapter and as recommended by the Township Landscape Architect.
A plan of basin planting shall be submitted to the Township for review
and approval.
(m)
If a stormwater management basin will serve
as a temporary sediment control device, the temporary sediment control
measures shall be shown including perforated riser pipes or standboxes,
filter berms, cleanout stakes and other measures as may be required
by Pennsylvania Department of Environmental Protection Chapter 102
regulations. Plans for such facilities shall require Montgomery County
Conservation District approval prior to implementation. Sedimentation
basins shall be in place prior to any earth-moving activities within
their tributary drainage areas. A note summarizing the above shall
be required on the record plan of subdivisions and land developments
as well as in land development agreement with the Township.
(n)
Stormwater management basins shall be in place
before the creation of any additional impervious surfaces on the site.
Runoff shall not be directed to an infiltration structure until all
tributary drainage areas are stabilized.
(o)
Where permanent retention (pond) facilities
are proposed, there shall be a safety ledge, three feet wide at the
maximum water surface level. If the pond is to be stocked, the Pennsylvania
Fish and Game Commission shall approve the stocking plan.
(p)
All basins shall have slopes of three horizontal
to one vertical (3:1 — 33.3%), or less on the basin's outer
berm and four horizontal to one vertical or less on the basin's inner
berm. The top or toe of any slope shall be located a minimum of five
feet from any property line. The maximum difference between the top
of berm elevation and the invert elevation of the outlet structure
shall be seven feet.
(q)
All portions of the detention basin bottom shall
have a minimum slope of 2%. The Township, on the recommendation of
the Township Engineer, may accept a basin bottom slope of less than
2% provided vegetative plantings consistent with current best management
practices are provided.
(r)
All basin embankments shall be placed in lifts
not to exceed one foot in thickness and each lift shall be compacted
to a minimum of 95% of Modified Proctor Density as established by
ASTM D-1557. Prior to proceeding to the next lift, the compaction
shall be checked by a Soils Engineer employed by the applicant/developer.
Compaction tests shall be run on the leading and trailing edge of
the berm along with the top of the berm. Verification of required
compaction shall be submitted to the Township Engineer prior to utilization
of any basin for stormwater management.
(s)
Emergency overflow facilities/spillway shall
be provided with basins in order to convey basin inflow in excess
of design flows, out of the basin, or in the event the outlet structure
becomes blocked and is unable to convey flow. Emergency spillways
discharging over embankments shall be lined. Lining for emergency
spillways shall incorporate native colors and materials where possible
including mono slab revetments, grass pavers and native stone. Mono
slab revetments and grass pavers shall be backfilled with topsoil
and seeded. The lining shall extend to the toe of the embankment on
the outside of the berm, and shall extend to an elevation of three
feet below the spillway crest on the inside of the berm. Vegetated
spillways may be utilized for spillways constructed entirely on undisturbed
ground (i.e., not discharging over fill material) if the designer
can demonstrate that flow velocities through the spillway will not
cause erosion of the spillway. A dense cover of vegetation shall be
rapidly established in such spillways by sodding or seeding with a
geotextile anchor. Such a vegetated spillway must be stabilized before
runoff is directed to the basin. The minimum capacity of all emergency
spillways shall be equivalent to the peak flow rate of the one hundred-year,
postdevelopment design storm (incoming to the basin) with the primary
outlet structure blocked. All spillway velocities shall be based upon
flows during an assumed clogged primary outlet condition.
(t)
In all cases, the discharge end of the basin
shall be provided with a properly designed outlet control structure
(headwall, orifice structure or other approved flow control structure),
culvert pipe, and endwall. Perforated riser pipes alone, without provision
for permanent outlet control structure (as stated above) and culvert
pipe, will not be acceptable for permanent basins.
(u)
The minimum top of basin berm width (at the
design elevation) shall be 10 feet. A cutoff trench (keyway) of impervious
material shall be provided under all embankments that require fill
material. The cutoff trench shall be a minimum of eight feet wide,
three feet deep and have side slopes of one horizontal to one vertical.
(v)
The minimum freeboard through the emergency
spillway shall be two feet. "Freeboard" is defined as the difference
between the design flow elevation through the spillway and the elevation
of the top of the settled basin berm.
(w)
Antiseep collars shall be installed around the
pipe barrel and shall be centered within the normal saturation zone
of the berm. The antiseep collars and their connections to the pipe
barrel shall be watertight. The antiseep collars shall be cast-in-place
and extend a minimum of two feet beyond the outside of the principal
pipe barrel. Precast collars may be permitted when approved by the
Township Engineer. A minimum of two collars shall be installed on
each basin outlet pipe.
(x)
A perforated riser, sized in accordance with
Montgomery County Conservation District requirements, shall be provided
at each basin outlet structure (if more than one is to be utilized)
for sediment control. Risers shall not be removed until such time
the entire area tributary to the basin has been permanently stabilized
and until approved by the Montgomery County Conservation District
and/or the Township Engineer.
(y)
All basin outlet pipes shall be watertight reinforced
concrete having "O-ring" joints. All joints shall be mortared. To
minimize clogging and to facilitate cleaning, outlet pipes shall have
an internal diameter of at least 18 inches and a minimum grade of
1/2%.
(z)
Energy dissipating devices (rock lining/rip-rap,
or other approved means) shall be provided at all basin outlets and
shall be sized in accordance with Pennsylvania Department of Environmental
Protection, Bureau of Soil and Water Conservation Publication, Erosion
and Sediment Control Program Manual, latest revision.
(aa)
Stone gabion baskets shall not be permitted
for use in construction of detention/retention basins.
(bb)
Access easement and stabilized drive to stormwater
detention facilities shall be provided for maintenance and operation.
This access easement shall be cleared and, when possible, be at least
30 feet in width. Proximity of detention facilities to public right-of-way
shall be encouraged in order to minimize the length of accessways.
Multiple accesses shall be encouraged for major facilities. The developer
shall provide access easements and drives of reinforced concrete checker-block
(backfilled with topsoil and seeded) or other similar paver acceptable
to the Township Engineer, over a six-inch bed of compacted PennDOT
type 2A coarse aggregate (or approved equivalent). Accessways to basins
shall be a minimum of 12 feet in width and be no steeper in slope
than 12 feet horizontal to one foot vertical. In addition, depressed
curb should be provided where the accessway enters a street/driveway
and the stabilized driveway shall extend from the bottom of the interior
basin berm embankment to the point of access to the basin. Access
easement shall be owned and maintained by the individual lot owner(s)
or homeowners' association but shall be established to permit access
by Horsham Township or its designee, for emergency inspection and/or
maintenance, at any reasonable time.
(cc)
The minimum distance between a proposed basin
discharge point and a downstream property boundary shall be 50 feet.
(10)
Best management practices. The Pennsylvania
Handbook of Best Management Practices for Developing Areas (1998)
shall serve as a design guide for structural and nonstructural best
management practices. Additional design guidance may also be obtained
from other related references prepared by the U.S. Environmental Protection
Agency, the Washington Metropolitan Council of Governments, the Natural
Resource Conservation Service, and the Pennsylvania Department of
Environmental Protection. In addition to the design requirements included
in the above documents, the following minimum design standards shall
be required for the best management practice identified below:
(a)
Infiltration trenches and dry wells shall meet
the following minimum design standards:
[1]
The lowest elevation of the infiltration area
shall be at least two feet above the seasonal high water table and
bedrock.
[2]
The infiltration system shall have positive
overflow controls to prevent storage within one foot of the finished
surface or grade.
[3]
The infiltration system shall be setback at
least 15 feet from all structures with subgrade elements (i.e., basements).
[4]
Infiltration systems shall be designed to infiltrate
the stored volume in 24 hours or less.
[5]
Infiltration rates shall not be used in computing
the storage volume of the infiltration system.
[6]
Surface inflows shall be designed to prevent
direct discharge of sediment into the infiltration system.
(b)
Dry basins shall be naturalized consistent with
the following minimum design standards:
[1]
Inlet structures and outlet structures shall
be separated to the greatest extent possible in order to maximize
the flow path through the basin. The minimum flow path length for
at least 50% the volume of water directed through the basin shall
be calculated using the following formula:
|
L = 3.1 (a/3.14).5
|
|
Where:
|
|
L
|
=
|
Minimum flow path length
|
|
a
|
=
|
Surface area of the basin in square feet at
the midpoint elevation between the lowest orifice elevation and the
emergency spillway elevation
|
[2]
Alternate design.
[a] To create a more freeform and curvilinear
basin so that from most edges of the basin the whole basin will not
be in view, the total perimeter length of the basin shall be increased
so that it is greater than or equal to the length derived by the following
formula:
|
P = 10.36 (a/3.14).5
|
|
Where:
|
|
P
|
=
|
Minimum basin perimeter length required
|
|
a
|
=
|
Surface area of the basin in square feet at
the midpoint elevation between the lowest orifice elevation and the
emergency spillway elevation.
|
[b] When the natural topography lends
itself to straight-sided basins, the basin shall contain an island
or peninsula planted with trees which is large enough and appropriately
placed to reduce the perceived size of the basin.
[3]
Basins shall be landscaped in accordance with the requirements of §
198-39E(7).
[4]
Inlet structures. The invert of the inlet pipe
into a basin shall be six inches above the basin floor or lining so
that the pipe can adequately drain after rain storms. Inlets shall
discharge into areas of the basin that slope toward the outlet structure.
[5]
Stabilization. Proper stabilization structures,
including stilling basins, energy dissipators, and channel lining,
shall be constructed at the outlets of all basins and emergency spillways.
The stabilization structures should control water to avoid erosion,
reduce velocities of released water and direct water so that it does
not interfere with downstream activities.
[6]
Discharge points. The minimum distance between
a proposed basin discharge point and a downstream property boundary
shall be 50 feet. The setback distance may be adjusted at the discretion
of the Horsham Township Engineer based upon factors such as topography,
soil conditions, and the location of structures.
(c)
Wet basins. Existing ponds or permanent pool
basins can be used provided they meet the following minimum design
standards:
[1]
The minimum permanent pool level shall be maintained
to allow sufficient depth throughout the year to reduce the growth
of unwanted vegetation and mosquitoes.
[2]
The pond must be of sufficient size to allow
the appropriate aquatic community needed to maintain a healthy pond
ecology.
[3]
An outlet structure shall be designed to allow
complete drainage of the pond for maintenance.
[4]
The design of a wet basin shall include the
determination of the proposed site's ability to support a viable permanent
pool. The design should take into account for such factors as the
required rate and quality of dry weather inflow, the quality of stormwater
inflow, seasonal and longer term variations in groundwater table,
and effects of suspected pollutant loadings. The Pennsylvania Fish
Commission and Natural Resource Conservation Service should be consulted
during the design of these facilities.
(d)
Grass swales shall meet the following minimum
design standards:
[1]
The bottom of the grass swale shall be two feet
minimum and six feet maximum with side slopes of 3:1 or flatter.
[2]
Grass swales proposed to satisfy the water quality requirements of Subsection
B(2)(c) shall be designed consistent with the following:
[a] The maximum flow velocity in the
grass swale for runoff from the water quality design storm (one-year,
twenty-four-hour) shall not exceed 1.5 feet per second (fps).
[b] The average slope of the grass
swale shall not exceed 4%, unless the swale is designed and protected
to provide adequate erosion control.
(e)
Riparian buffers proposed to meet the water
quality standards shall meet the following minimum requirements:
[1]
The minimum overland flow length through the
buffer shall be 75 feet.
[2]
The maximum overland flow length contributing
runoff to the boundary of the riparian buffer shall be 150 feet for
pervious surfaces and 75 feet for impervious surfaces.
[3]
The average contributing overland slope shall
not exceed 5%.
[4]
Runoff shall enter the riparian buffer as sheet
flow. A level spreading device shall be utilized where sheet flow
can no longer be maintained.
[5]
The riparian buffer shall be specifically designated on the final subdivision and/or land development plan and landscaped in accordance with the requirements of Chapter
230, Zoning, §
230-49E(7), and as recommended by the Township Landscape Architect. Plan notes should also indicate the portions of the riparian buffer being used to satisfy the requirements of Subsection
B(2)(c). Generally, the riparian buffer should be increased in effectiveness while maintaining a natural state as much as possible to maximize water quality benefits.
(f)
All disturbed topsoil on site is to be redistributed
on site in areas not covered by impervious surfaces. No removal of
topsoil from a site is allowed unless approved by Horsham Township.
H. Design submission.
(1) Stormwater management plans for a proposed subdivision
and/or land development shall contain the following:
(a)
Mapping of proposed watershed areas (predevelopment
and postdevelopment).
(b)
All identified impacts the subdivision and/or
land development will have on downstream conditions.
(c)
Computations of the stormwater runoff for all
points of runoff concentration, before, during and after development
including all supporting data.
(d)
Complete drainage systems. All existing drainage
features that are to be so identified with an explanation of the operations
of the facilities.
(e)
Plans depicting all existing and proposed drainage
facilities affecting the subject property.
(f)
Plan of the proposed stormwater drainage systems
including storm sewer piping and inlets, runoff control devices (basins,
etc.) and drainage channels.
(h)
Design computations for the sizing of the basin
pipe barrel and outlet structure as well as the perforated riser.
(i)
Stage versus storage curve for basin(s).
(j)
Basin routing calculations including stage versus
storage versus outflow rating curve.
(k)
Plan depicting the basin(s) berm embankment
and outlet structure, including the top of berm elevation, top width
of berm, berm side slopes, emergency spillway elevation, width, lining
material, and sizing calculation, relevant elevations of the outlet
structure and/or outlet pipe, outlet pipe size, length, slope, and
material type, size, number and spacing of the antiseep collars, and
size and location of the basin berm cutoff trench, etc.
(l)
Detailed plan of all proposed off-site improvements
(if any).
(2) All plans showing the proposed stormwater management
facilities construction must be accompanied by a complete design submitted
by a professional engineer registered in the State of Pennsylvania.
(3) When subdivisions or land developments are submitted
to the Township for approval in sections, a complete storm sewer design
for the proposed subdivision and land development shall be submitted.
The proposed design must include the entire tract and not a portion.
(4) If only a section of a subdivision or land development
is contemplated for construction, the engineer shall show how he proposes
to handle stormwater from this section in order to prevent damage
to adjacent properties. If temporary construction is required, the
engineer shall include such structures in the plan submitted.
I. Maintenance responsibilities.
(1) General responsibilities.
(a)
The owner of stormwater management facilities
shall be responsible for their proper maintenance during and after
development. A maintenance plan shall be prepared for review by the
Township Engineer, approved by Horsham Township and shall be executed
and signed by the applicant/developer.
(b)
On or before completion of subdivision or land
development improvements, the permanent stormwater management system
for a tract shall be fully installed and functional in accordance
with the approved stormwater management plan. Temporary sediment trapping
facilities in detention basins upon inspection and approval by the
Township Engineer shall be converted into permanent stormwater management
basins; additional facilities designed to serve more than an individual
lot shall begin operation. All such work shall be specified in the
approved stormwater management plan.
(2) Stormwater management facilities ownership and maintenance.
All stormwater management facilities identified within an approved
stormwater management plan shall be owned and maintained by one, or
a combination, of the following entities:
(a)
Individual lot stormwater facilities. Stormwater
management facilities and systems that are located on an individual
lot are the responsibility of that landowner to maintain. All deeds
shall incorporate the maintenance responsibilities specified in the
approved maintenance plan, making explicit individual owners responsibilities
for stormwater management measures and for the common property.
(b)
Homeowners' or condominium association ownership
(other than stormwater facilities located on individually owned lots).
A single entity taking the form of a private corporation, partnership
firm, estate or other legal entity empowered to own real estate exclusive
of individual lot owners shall be set up to manage stormwater management
facilities that are suitable for such management and perform other
functions defined in this section. Maintenance responsibilities specified
in the approved maintenance plan should be referenced on the plan
and recorded into lot deeds, homeowners or condominium association
articles of incorporation, or some other permanent legal document.
(c)
Municipal ownership. Where Horsham Township
has accepted an offer of dedication of the permanent stormwater management
facilities, Horsham Township shall be responsible for maintenance.
Municipal ownership notwithstanding, the applicant is required to
prepare a stormwater management plan including a maintenance component,
as defined above. Upon approval of the stormwater management facilities
by Horsham Township, the applicant shall provide a financial security,
in a form approved by Horsham Township Solicitor for maintenance guarantees,
as follows:
[1]
Long-term maintenance bond. The long-term maintenance
bond shall be in an amount and for a time period as determined by
Horsham Township. The estimated annual maintenance cost for the facilities
shall be based on a reasonable fee schedule provided by the Township
Engineer and adopted by Horsham Council.
[2]
Documentation. The terms of the maintenance
guarantees shall be documented as part of the stormwater management
plan and the maintenance plan subpart.
(3) Maintenance plan. A maintenance plan shall be prepared
to identify the ownership and maintenance responsibilities for all
stormwater management facilities. At a minimum the maintenance plan
shall include the following:
(a)
Any obligations concerning perpetuation and/or
maintenance of natural drainage or infiltration facilities, and other
facilities identified within the stormwater management plan.
(b)
A description of the facilities and systems
on the lot, as called for above, setting forth in deed restrictions
binding on the landowner's successors in interest.
(c)
Assurances that no action will be taken by any
lot owner to disrupt or in any way impair the effectiveness of any
stormwater management system, setting forth in deed restrictions the
ability of the Township to take corrective measures if it is determined
at any time that stipulated permanent stormwater management facilities
have been eliminated, altered, or improperly maintained, including
the ability of the Township to cause the work to be done and lien
all costs against the property should the required corrective measures
not be taken by the lot owner within a period of time set by the [Municipal]
Engineer.
[Amended 10-9-2002 by Ord. No. 4019]
In addition to the requirements of §
198-37I as set forth above in this chapter, all completed stormwater management facilities, including detention/retention basins, shall be surveyed by a professional land surveyor licensed in the State of Pennsylvania, to verify compliance with the character of stormwater management facilities as depicted on the approved final plan (or subsequently approved revision thereof). As-constructed plans shall be submitted to Horsham Township for review and approval, upon completion of construction of all facilities and prior to offer of dedication of any public facilities and/or submission of financial security for the required maintenance period. Public facilities will not be accepted by Horsham Township until such time the as-constructed plans have been reviewed and approved by the Township Engineer.
All water and gas mains and other underground
utility facilities shall be installed prior to street paving at locations
approved by the Township for the full width of the right-of-way.
A. Underground utilities. All water and gas mains shall
be installed underground. All electric, telephone, and communication
services both main and service lines shall be provided by underground
cable/conduit, installed in accordance with the prevailing standards
and practices of the utility or other companies providing such services,
except where it is demonstrated to the satisfaction of Council that
underground installations here required are not feasible because of
physical conditions of the lands involved. All main underground cables/conduit,
which are within the right-of-way of a street, shall be located as
much as possible, between the curb/edge of cartway and the back edge
of the sidewalk or as otherwise specified by Council.
(1) In order to promote and facilitate the undergrounding
of utility distribution lines, a letter of endorsement shall be required
from the suppliers of utility service (not limited to electrical,
telephone, or cable television) of the developer's choice, wherein
the applicant acknowledges that underground utility service shall
be placed on the final plan as a prerequisite to final approval of
such plan.
(2) The provisions in this chapter shall not be construed
as to limit or interfere with the construction, installation, operation
and maintenance of public utility structures or facilities which may
hereafter be located with public easements or rights-of-way designated
for such purposes.
Wherever practicable, provision shall be made
for suitable open space for parks, playgrounds, and recreational areas.
In commercial areas, provision shall be made for suitable open space
for walkways (connecting parking facilities with commercial structures),
malls, sitting areas and other amenities. Due consideration shall
be given to the preservation of natural features, including large
trees, groves, waterways, scenic points, historical resources, and
other community assets.