The provisions of this article are enacted in order:
A. To recognize the need to direct increasing urbanization to appropriate
locations in the Township;
B. To accommodate for housing of all required forms at a scale and design
configuration which compliments the semi-rural, open character of
the Township;
C. To encourage desirable innovations in residential and nonresidential
design which preserve and incorporate the agricultural, natural, scenic,
historic and open space resources of the Township;
D. To provide uniform procedures which relate the type, design and layout
of a unified development to the particular physical characteristics
of site;
E. To establish design provisions which allow for flexible lot layout
and more efficient use of land and open space than is afforded under
conventional zoning;
F. To prolong the effective life of community services and facilities,
maintain fiscal solvency of the Township and protect property values
within the Township;
G. To develop large tracts of land in accordance with Article
XIV, Natural Resource Protections; and
H. To further implement the goals and objectives of the Township's
Comprehensive Plan and the Open Space, Recreation and Environmental
Resources Plan.
The provisions of this article shall be interpreted in relation
to the goals and objectives of the Thornbury Township Comprehensive
Plan. Every development plan for approval of a PRD shall be based
and interpreted in relationship to the Comprehensive Plan. Specifically,
the development plan shall be designed to:
A. Guide and encourage the future development of Thornbury Township
in accordance with Comprehensive Planning of land use and population
density that represents the most beneficial and convenient relationship
among the agricultural, residential, commercial and other areas within
the Township, having regard to their suitability for the various uses
appropriate to each of them and their potential for such uses;
B. Minimize the grading or other alteration of the site, in order, among
other things, to prevent soil erosion and to conserve important vegetative
and scenic resources;
C. Protect the character and the social and economic stability of the
Township and encourage orderly and beneficial growth;
D. Protect and conserve the value of land and buildings throughout the
Township appropriate to the various uses proposed;
E. Aid in bringing about the most beneficial relationship between land
use and the traffic circulation patterns throughout the Township,
having particular regard to the avoidance of congestion in the roads
and the provision of safe and convenient access appropriate to the
various land uses;
F. Aid in providing a guide for public policy and action in the efficient
provision of public facilities and services, in the provision of safe
and proper sanitary sewage disposal;
G. Protect and preserve historic resources as shown on the Thornbury
Township Historic Resources Map; and
H. Protect and conserve those resources mapped in the Open Space, Recreation
and Environmental Resources Plan and in particular the water resources
(Map 2), steep slopes (Map 3) and biotic resources (Map 4).
The following conditions shall be satisfied prior to the consideration
of the Board of Supervisors on any application request for a PRD:
A. The tract of land so developed shall be in single ownership or, in
the case of multiple ownership of the tract, the application shall
be filed jointly by all of the owners of the tract and, in any case,
it shall be agreed that the tract will be developed, within the time
limits specified by the Board, under a single direction and in the
manner approved;
B. The tract shall be located entirely in the PRD District;
C. Tract size.
(1)
A tract in the PRD District shall have a minimum contiguous
area of 100 acres. In the event that the minimum tract acreage in
the PRD District is not contiguous due to separation by one or more
public roads or public rights-of-way, such separation shall not preclude
development of the tracts as a PRD if they are developed in a unified
manner as a single PRD.
(2)
Those portions of the tract encumbered by land conservancy easements
or similar easements requiring the eased land to be maintained as
open space or parkland shall not be included in the tract area for
purposes of the calculation of density of dwellings.
D. All PRDs shall have primary access onto a designated collector road;
E. The tract shall be served by either an approved community or public
water and community or public sewer systems;
F. Soil and subsoil conditions must be suitable for excavation and site
preparation and for on-site water systems, where applicable;
G. Impact studies shall be developed in accordance with §
155-704 and made part of the application for tentative plan approval so that existing and possible negative impacts will be mitigated;
H. The development will preserve and incorporate a limited visibility
of the proposed development into the proposed landscaping, to the
maximum extent possible, taking into consideration natural features
such as topographic conditions, ponds, streams, tree stands, shrubs
and other vegetation;
I. The topography of the tract of land and its drainage shall be suitable
for the proposed development, with consideration given to preventing
soil erosion;
J. All dwelling units shall have direct access to internal streets within
the proposed PRD; and
K. The application shall provide a minimum of 40% open space.
In order to facilitate a comprehensive review of site suitability,
the following standards shall be applied to sites being considered
for a PRD except wherein 25 acres are developed for mobile homes,
wherein the mobile home ordinance standards shall apply:
A. Modification of otherwise applicable standards.
(1)
The uniqueness of each proposal for PRD may require that the standards and specifications in the other parts of this chapter and/or Chapter
115, Subdivision and Land Development, may be subject to modification for such features as: the width and surfacing of the streets and highways; alleys; public utilities; curbs; gutters; sidewalks; pathways/trails; streetlights; public parks and playgrounds; school grounds; stormwater drainage; water supply and distribution; sanitary sewers and sewage collection and treatment; parking spaces and areas; and setbacks and separations of structures in relation to each other and property lines.
(2)
The Board of Supervisors may modify certain standards and specifications, provided that the modifications of such standards and specifications are: consistent with the public interest; consistent with the purpose and intent of this chapter; and that such modification represents the least change to the chapter. Where there is conflict between standards and specifications of this article and other ordinance provisions, the Board of Supervisors shall determine which ordinance provisions will prevail; and where not specifically modified by the Board of Supervisors, the provisions of the other parts of this chapter and Chapter
115, Subdivision and Land Development, shall fully apply to developments under this article.
B. General tract considerations. In order to determine which areas of
a prospective tract are suitable for development and which areas should
remain in open space, a thorough analysis of the natural and man-made
resources of the site shall be mapped and described in a written report.
The Township shall require site design proposals to address the results
of these analyses in a way which will conserve natural resources.
The analysis shall include the following inventory:
(1)
Natural features such as lakes, streams, wetlands and wooded
slopes to be preserved and incorporated into the proposed landscaping
of the development plan to the maximum extent possible. The applicant
shall demonstrate the means whereby trees and other natural features
shall be protected during construction. The location of such trees
and other natural features must be considered when planning and designing
such features as: common open space, locations of buildings, underground
utilities and services, sidewalks, pathways, paved areas and finished
grade levels.
(2)
An analysis of the watershed in which the tract is located,
including site-specific analysis of water resources such as streams,
drainage swales, floodplain areas, wetlands and areas with high water
table soils. Water bodies shall be preserved in their natural state
and incorporated into the design of the development.
(3)
An analysis of rock formation characteristics underlying the
tract, including aquifers, areas of shallow soil and rock outcroppings
and areas which are unsuitable to serve as foundation materials.
(4)
An analysis of the terrain of the tract, including the mapping
of elevation in at least twenty-foot bands on a topographic elevation
map and the delineation of slope into the following categories: 0%
to 15%, 15% to 25% and over 25% slope. The mapping of slopes shall
be performed using a two-foot contour interval aerial or field-derived
topographic survey. All moderate and steep slopes shall be mapped.
However, restrictions on use of the slopes shall apply whenever three
or more consecutive two-foot contours (six cumulative feet or more)
are impacted. Slopes exceeding 25% shall be reserved in their natural
state. Seeding, sodding and other plantings shall be applied to stabilize
steep slopes and to enhance the appearance of open areas.
(5)
Where adequate surface drainage is not possible by grading alone,
a supplementary drainage system approved by the Township shall be
required.
C. General design guidelines. The following guidelines shall apply:
(1)
All housing shall be designed with regard to the topography
and natural features of the site. All proposed building locations
shall be set back at least 10 feet from slopes in excess of 25%, floodplain
areas and wetlands. In addition, all proposed building locations shall
be free of high water table soil types and unstable geologic formations.
The effects of prevailing winds, seasonable temperature and hours
of sunlight on the physical layout and form of the proposed development
shall be demonstrated.
(2)
Variations in the building design shall be required to create
architectural interest in the layout and character of dwellings. Such
variations may be achieved, among other ways, through the design of
buildings to include such features as porches, courtyards or atrium
spaces formed by attached dwellings or multifamily buildings and arcade/foyer
spaces formed by nonresidential buildings.
(3)
All dwellings shall be designed to ensure natural light and
ventilation, while affording maximum privacy.
(4)
Access to vehicular parking and pedestrian walks shall be convenient
to dwellings without creating a nuisance or detracting from privacy
of residents. All dwellings shall be served by local streets.
(5)
The entire perimeter of the tract(s) to be developed shall include
a landscape buffer in accordance with this article. However, if the
Design Review Committee determines that sufficient existing vegetation
and/or topography buffer and screen views of the proposed development,
the buffer requirement may not be required. All proposed residential
principal structures shall be set back from the tract boundary a minimum
distance of 100 feet, and all proposed residential accessory structures
shall be set back at least 50 feet from the tract boundary, both of
which shall be measured from the adjacent property lines, or, in the
case of a street, alley, roadway or highway, from the ultimate right-of-way
lines.
(6)
Dwelling units and lots shall be clustered to minimize the disruption
of the site and to provide for an adequate open space design.
(7)
This article is intended to encourage good quality development
by taking into consideration the appearance of all elevations and
layouts of buildings and external spaces and materials used therein.
The Design Review Committee shall evaluate the quality of development
proposed and may make recommendations to the Board to improve such
quality.
(8)
Lots, buildings, roads and other structures shall be grouped
into clusters so as to create a sense of neighborhood. A sense of
neighborhood shall be achieved by incorporating the following features
into the development plan: a neighborhood center; parks, playgrounds
or other recreation facilities within a one-fourth-mile radius of
a group or cluster of dwellings; a street, sidewalk and pathway system
designed in an integrated manner and leading to and from the neighborhood
center; and parking on the side and rear of buildings in the neighborhood
center so as to create and promote pedestrian space between the building
façades and the street lines.
(a)
A sense of neighborhood may also be created by the design and
placement of dwellings and structures in the form of a traditional
neighborhood with: buildings 25 feet from the street line and detached
garages accessible from a rear service alley; front porches; street
trees; sidewalks on both sides of the street; and pathways leading
to parks and a neighborhood center.
(9)
Development shall be located on areas of the tract to minimize
the disruption of sensitive environmental features such as hedgerows,
woodlands, steep slope areas and water bodies. These features shall
be incorporated into the common open space to provide visual screening
between clusters. Clusters of lots shall be defined and separated
by common open space in order to allow direct access to open space
and recreational facilities. The common open space between clusters
shall have a minimum width of 100 feet. A minimum setback of 20 feet
from the exterior walls of all multiple-dwelling structures shall
be achieved in order to define the boundary of the common open space
close to proposed buildings.
(10)
All areas designed for open space and recreational use shall also conform to §
155-709.
(11)
Historic resources, as shown on the Thornbury Township Historic
Resources Map, shall be protected and, when not proposed as a residence,
shall be preserved in a setting surrounded by open space. The applicant's
proposal for protection and preservation shall include provisions
for future ownership and maintenance approved by the Design Review
Committee.
(12)
Eighty percent of the area of the minimum required lot size
shall be outside areas subject to floodplain management, wetlands,
steep slopes, and stormwater management basins. For purposes of this
regulation, the area of a stormwater basin shall be calculated by
measuring the area of the water surface within the basin projected
to exist at the level of the basin overflow. Every lot shall be free
of wetlands, floodplains and steep slopes. Whenever this subsection
conflicts with any other provision of this section, the stricter regulation
shall apply.
D. Optional sketch plan review and discussion.
(1)
Although optional, the applicant is strongly urged to submit
a sketch plan for review and discussion with the Township.
(2)
The sketch plan shall embody and be accompanied by maps, plans and other data to express: the general tract considerations as set forth in §
155-703B above and the general design guidelines of §
155-703C above, except that the contour interval for slope mapping may be at 10 feet.
(3)
The sketch plan shall include typical elevations of the proposed
buildings.
(4)
The sketch plan review and discussion process is intended to
provide the Thornbury Township Board of Supervisors, Planning Commission
and Design Review Committee with an opportunity to engage in a meaningful
analysis of design issues, alternatives and options.
(5)
Through the review and discussion of the sketch plan, the applicant
and the Township can explore conceptual design solutions for ingress/egress,
vehicular and pedestrian circulation, open space, recreational areas,
the use of developable areas, the relationship of developable areas
to one another, the location and form of the design to create a sense
of neighborhood and other matters.
The applicant shall be responsible for the preparation of the
following impact studies. These studies shall be submitted as part
of the application for tentative plan approval. This supporting data
shall be designed to assist the Township in the review of the proposal
and offer documentation on how negative impacts associated with the
project shall be minimized and mitigated.
A. Traffic impact study. The applicant shall hire a Transportation Engineer/Traffic Consultant to prepare said study with the approval of the Township. The study shall follow current PennDOT guidelines for such studies and the methodology shall be subject to Thornbury Township review and approval. The study area shall include all intersections within 2,000 feet of the tract and any other major intersections as recommended by the Planning Commission. The study shall assess the impact of a proposed development on the highway network and Township roads, to identify traffic problems associated with the proposed development, to identify potential solutions and to present improvements to be incorporated into the project design. Mitigating measures shall include methods of maintaining the capacity of the road network within the study area. Mitigation measures shall be proposed to minimize adverse impacts, and the Board of Supervisors may condition any PRD Plan approval on such mitigation in accordance with §
155-714.
B. Community impact study. The applicant shall submit an impact study
which will sufficiently assess the impact the development will have
on the Township and the level of public services. The study shall
address the manner in which identified negative impacts shall be mitigated
by the applicant to enable the Board of Supervisors to ascertain if
the proposed development is capable of being serviced by existing
public services and, further, to specify what efforts the applicant
has made to minimize the demand for services. The study shall analyze
the following services and facilities:
(1)
Fire protection. The impact the proposed development will have
on fire protection capability, including, but not limited to, municipal
water supply, pumping capacity and specialized equipment, shall be
analyzed. The applicant must adequately demonstrate what effect the
proposed development will have on these factors and its ability to
meet any specialized needs so that the development will not have any
impact on the public safety by adversely affecting the fire protection
capability available to the community.
(2)
Solid waste. A study to determine what amount of solid waste
will be generated as a result of the development shall be prepared.
The study shall identify what method will be used to dispose of the
solid waste and what effort will be directed toward recycling solid
waste.
(3)
Historical. A study shall be made that determines the location
of historic properties and structures both on and within 200 feet
of the site and the effect said development will have on these properties
and structures and what effort the developer will make to preserve
such historic properties and structures. All historic resources, as
shown on the Thornbury Township Historic Resources Map, shall be preserved.
(4)
Water. A study of the amount of water needed for domestic and
fire use shall be provided. The study shall indicate the location
of the source and anticipated pressure of proposed source of water.
The applicant shall pay for the cost of improvements to a public water
system if connection to said system is proposed.
(5)
School facilities. A study to determine the impact the development
will have on school enrollment within the West Chester Area School
District shall be provided. The study shall project the number of
school-aged children to be generated by the development. Calculations
shall be made for each dwelling type proposed and shall utilize demographics
of the U.S. Census, the Township Comprehensive Plan and/or other available
sources.
(6)
Fiscal impact. The applicant shall submit a report which identifies
the fiscal consequences of the proposed PRD. The report shall be prepared
by a qualified professional and shall address:
(a)
The economic and fiscal characteristics related to the proposed
development, including a profile of the Township, county and school
district revenues which the proposal may generate and the Township,
county and school district costs it may create. Such information shall
be related to initial, phased and completed development conditions.
(b)
The extent to which the development can be expected to be or
not to be detrimental to the Township for annual and capital budgeting
purposes.
(c)
The ability or inability of the development to make adequate
provision for educational, recreational and other essential community
facilities which will be required as a result of the development.
Other essential community facilities shall include a day-care center
and other civic amenities as part of the neighborhood center.
C. Environmental impact study. The applicant shall submit a report which
identifies the environmental consequences of the proposed PRD and
the measures proposed to mitigate environmental impacts. Said study
shall be prepared by a licensed engineer, architect, landscape architect
or a certified land planner. Particular emphasis shall be placed on
the effects of the proposed project on the site and abutting properties.
The study shall consist of text, tables, mapping and photography designed
to illustrate how environmental resources will be conserved and/or
protected. The study shall include, as a minimum, the following components:
(1)
Site analysis plan. A composite map shall be prepared which
depicts natural and man-made features of the site. Said plan shall
be displayed at a scale of not greater than one inch equals 100 feet.
The plan shall, as a minimum, identify and analyze the following features:
(a)
Topographic conditions of the site depicted by existing contours at vertical intervals of two feet based on information derived from either actual field survey or aerial topographic interpretation, consistent with National Mapping Accuracy Standards. Slope shall be accurately depicted through the use of shading between contour intervals for slope between 15% and 25% and for slope equal to or exceeding 25%. Datum, which elevations refer to, shall be identified. Points of highest elevation, including hilltops and ridgelines, shall also be clearly noted. [Refer to §
155-703B(4) for mapping criteria.]
(b)
All existing watercourses and water bodies, including such features
as ponds, creeks and intermittent streams, shall be identified.
(c)
The actual limits of the floodplain and wetlands shall be accurately
presented on the plan. Both floodplain and wetland limits shall be
based on actual field survey and include the limits of hydric soil
conditions and the designated one-hundred-year flood hazard area as
defined by the Flood Hazard Map of FEMA. Wetland areas shall be based
upon the criteria of the U.S. Army Corps of Engineers and the Pennsylvania
Department of Environmental Protection and include all hydric soil
areas.
(d)
All soils on the tract, depicted by the limits of soil series
as identified by the Soil Survey for Chester and Delaware Counties,
by the USDA Soil Conservation Service. A table listing the soil characteristics
pertaining to slope, depth to water table, depth to bedrock and septic
tank limitations shall be included.
(e)
The location of all tree masses, hedgerows and individual trees
shall be shown as part of the topographic survey plan for the property.
The predominant type of all trees shall be noted, along with any plants
or natural areas as identified in the 1994 "Natural Areas Inventory
for Chester County, Pennsylvania."
(f)
The limits of all existing streets, utilities, pipelines and
associated rights-of-way or easements shall be identified.
(g)
The limits of each geologic formation or rock type on the tract
shall be plotted. The location and type of rock outcroppings shall
be identified.
(h)
The location of all buildings and structures, including ruins
and remnants. Structures of historic and archaeological significance
shall be documented. Such resources shall include those listed on
the National Register of Historic Places, the Pennsylvania Inventory
of Historic Places and the Chester County Historic Site Survey.
(i)
An analysis of access to the site, including the identification
of existing accesses and optimum points of access in terms of sight
distance, intersection alignment, turning movement conditions and
other important factors.
(2)
Site character and current conditions. A combination of narrative and series of photographs depicting the general character of the site as viewed from ground level and from an aerial photographic base. Key aspects of the site analysis study in §
155-704C(1) shall be addressed, including woodlands, hedgerows, fields, primary views into the tract, water bodies and streams, significant views and the like.
(3)
Land use conditions. A narrative shall be prepared which defines
current and past land use activities of the site. Current land uses
and the location of buildings and structures, including the distance
each is set back from the tract boundaries.
(4)
Historic and archaeological resource protection. Methods of
conserving and protecting the resources identified in the site analysis
plan shall be described through a combination of narrative and maps.
(5)
Visual resource protection. Methods of preserving the visual
resources associated with the tract shall be described, including
vistas, ridgelines, hilltops and stream valleys which can be seen
from public streets. Preservation methods shall include conservation
of existing features, landscaping, berming, the use of buffers and
creative building setbacks through the placement of buildings and
structures in less visually prominent locations.
(6)
Adverse effects of the project. The study shall identify adverse
impacts which cannot be precluded through design alterations. The
narrative shall identify whether the impact poses an immediate or
indirect impact on a particular resource or characteristic of the
site.
(7)
Mitigating measures. The study shall identify and depict measures which will mitigate the impacts identified in §
155-704C(6). The narrative shall identify measures that are required by existing standards and those which are unique to the proposed project. All adverse impacts shall be mitigated. All mitigation measures shall be clearly depicted on a separate plan sheet to be entitled "Impact Mitigation Plan."
D. The Board of Supervisors may require additional specific information
and analysis as it deems necessary to adequately assess traffic impacts,
community impacts, environmental impacts and fiscal impacts and to
prescribe mitigation measures.
The uses permitted in a PRD shall be limited to:
A. A combination of dwelling units in single-family detached, two-family or multifamily detached, semidetached and attached when in accordance with the provisions of §
155-707;
B. Those nonresidential uses deemed to be appropriate for the incorporation
in the design of the PRD, including, but not limited to, a neighborhood
center, community facilities, day-care centers, agricultural facilities
and uses and recreational facilities;
C. Accessory uses customarily incidental to the foregoing uses; and
D. Use of common open space areas.
(1)
Common space areas may include:
(a)
Agriculture, including cultivation of the soil; raising and
harvesting of products of the soil, including nurserying, horticulture
and forestry; or any other agricultural use which the Board of Supervisors
deems appropriate for incorporation within PRD.
(b)
Natural areas, including, but not limited to, woodland, meadow,
wetlands, streams, boundary buffer or similar conservation-oriented
area.
(c)
Lawn: a grass area with or without trees which may be used by
the residents for a variety or purposes and which shall be mowed regularly
to ensure a neat and tidy appearance.
(d)
Outdoor recreation area, either active or passive.
(e)
Sewage disposal system involving land application and groundwater
recharge, but excluding buildings and other aboveground structures
associated with such facilities.
(2)
Common open space areas shall not include:
(a)
Streets and off-street parking areas.
(c)
The 4,000 square foot equivalent lot area for multifamily dwellings.
(d)
Twenty feet from any exterior walls of any townhouse or apartment
dwelling.
(e)
Stormwater management facilities, unless designed as a pond,
wet year-round.
A PRD shall comply with the following dwelling unit combination
to ensure a variety of housing types:
A. A minimum of 30% single-family;
B. A minimum of 5% two-family;
C. A minimum of 20% multifamily;
D. The remainder of the housing units shall be left to the discretion
of the developer, except that single-family dwellings shall comprise
no more than 75% of the total number of housing units; and
E. At the discretion of the Board of Supervisors, dwelling unit combinations
may be modified upon the showing of good cause by the applicant.
The following area and bulk requirements shall apply to all
residential uses permitted within a PRD:
A. Single-family.
(1)
Base minimum lot size: 10,000 square feet.
(2)
Bonus minimum lot size: 8,000 square feet.
(3)
Minimum lot width (base and bonus).
(4)
Minimum front yard depth: 25 feet.
(5)
Minimum side yard: 10 feet.
(6)
Minimum rear yard depth: 30 feet.
(7)
Base maximum building coverage: 30%.
(8)
Bonus maximum building coverage: 35%.
(9)
Base maximum lot coverage (total): 40%.
(10)
Bonus maximum lot coverage (total): 50%.
(11)
Maximum building height: 35 feet.
B. Two-family (twin and duplex).
(1)
Base minimum lot size per dwelling unit: 5,000 square feet.
(2)
Bonus minimum lot size per dwelling unit: 4,000 square feet.
(3)
Minimum lot width per dwelling unit (base and bonus).
(4)
Minimum front yard depth: 25 feet.
(5)
Minimum side yard: 10 feet.
(6)
Minimum rear yard depth: 30 feet.
(7)
Base maximum building coverage: 30%.
(8)
Bonus maximum building coverage: 35%.
(9)
Base maximum lot coverage (total): 40%.
(10)
Bonus maximum lot coverage (total): 50%.
(11)
Maximum building height: 35 feet.
C. Multifamily.
(1)
Base minimum allowable lot area to be reserved for each dwelling
unit, exclusive of common parking and street areas: 4,000 square feet.
(2)
Bonus minimum allowable lot area to be reserved for each dwelling
unit, exclusive of common parking and street areas: 3,000 square feet.
(3)
Minimum distance between buildings: 50 feet.
(4)
Minimum setback from common parking: 20 feet.
(5)
Base maximum building coverage: 25%.
(6)
Bonus maximum building coverage: 30%.
(7)
Base maximum lot coverage: 40%.
(8)
Bonus maximum lot coverage: 50%.
(9)
Maximum building height: 35 feet.
(10)
Maximum building length: 160 feet.
(11)
Minimum setback from common open space: 20 feet.
(12)
The following additional standards shall apply when individual
lots are proposed:
(a)
Minimum front yard depth: 25 feet.
(b)
Minimum rear yard depth: 50 feet.
(c)
Maximum building coverage: 25%.
(d)
Maximum lot coverage (total): 30%.
(13)
Maximum number of dwelling units per building: 12 units.