1. BMP 5.5.2: Concentrate Uses Area wide through Smart Growth
  2. Practices
      1. Key Design ElementsPotential Applications
      2. Stormwater Functions
      3. Water Quality Functions
    1. Variations
      1. and Cities
      2. 3. Mixing and Matching Smart Growth Techniques: Public and Private
    2. Applications
      1. Growth Boundaries:
      2. Effective Agricultural Zoning:
      3. Effective Agricultural Zoning:
    3. Design Considerations:
    4. Detailed Stormwater Functions
    5. Construction Sequence
    6. Maintenance Issues
    7. Cost Issues
      1. Specifications

BMP 5.5.2: Concentrate Uses Area wide through Smart Growth

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Practices
On a municipal, multi-municipal or areawide basis, use of "smart growth" planning techniques, including
neo-Traditional/New Urban planning principles, to plan and zone for concentrated development
patterns can accommodate reasonable growth and development. These practices direct growth to
areas or groups of parcels in the municipality that are most desirable and away from areas or groups of
parcels that are undesirable. BMP 5.5.2 can be thought of as Super Clustering that transcends the
reality of the many different large and small parcels that exist in most Pennsylvania municipalities.
Clustering parcel by parcel simply cannot accomplish the growth management that is so essential to
conserve special environmental and cultural values and protect special sensitivities. These smart
growth techniques include but are not limited to, transfer of development rights (TDR), urban growth
boundaries, effective agricultural zoning, purchase of development rights (PDR) by municipalities,
donation of conservation easements by owners, limited development and bargain sales by owners, and
other private sector landowner options. "Desirability" is defined in terms of environmental, historical
and archaeological, scenic and aesthetic, "sense of place," and quality of life sensitivities and values.
Key Design Elements
Potential Applications
Residential:
Commercial:
Ultra Urban:
Industrial:
Retrofit:
Highway/Road:
Yes
Yes
Yes
Yes
Yes
Limited
Stormwater Functions
Volume Reduction:
Recharge:
Peak Rate Control:
Water Quality:
Very High
Very High
Very High
Very High
Water Quality Functions
TSS:
TP:
NO3:
Preventive
Preventive
Preventive
.
Establish baseline growth and development context for the
municipality or multi-municipal area (how much of what by when
and where, using decade increments, plus ultimate build out).
.
On macro level (defined as municipality-wide, multi-municipality-
wide, areawide), define criteria for growth "desirability"
(opportunities) and "undesirability" (constraints) on a multi-site
and/or municipality-wide and/or areawide basis.
.
Apply these "desirability" and "undesirability" criteria.
.
Contrast baseline growth and development (first step) with third
step; highlight problems.
.
Apply smart growth techniques as needed to re-form "business
as usual" future to max out "desirability" and "undesirability"
performance. Techniques include: transfer of development rights
(TDR), urban growth boundaries, effective agricultural zoning,
purchase of development rights (PDR), donation of conservation
easements by owners, limited development and bargain sales by
owners, and other private sector landowner options.
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Variations
Because of the broadness of this BMP and its macro scale, variations in this BMP can be substantial.
Variations include: 1) how areas deemed to be desirable for growth are defined, whether clusters,
hamlets, villages, towns and/or cities; 2) how areas deemed undesirable for growth are defined
(conserving natural resources, agricultural lands and other vital resources); and 3) how any of this is
made to happen and what blend of smart growth techniques can be applied (where and when) to
implement 1 and 2.
1. Defining Desirable Growth – Opportunities for Growth: Clusters, Hamlets, Villages, Towns
and Cities
The vision for growth and development can take many different forms and can vary substantially
depending upon the respective municipality, group of municipalities, or area. Rural areas (Figure 5.5-1)
striving to preserve their rural character can concentrate development through adherence to building
onto or even creating Hamlets and Villages. If adjacent communities exist, development can be
directed into the town or at the town edge (Figure 5.5-2). Clustering (see BMP 5.5.1) on a site-by-site
basis is superior from a site perspective but yields a pattern that is less than optimal from a multi-site or
area wide perspective (Figure 5.5-3). However, this overall pattern is vastly preferable to the business
as usual approach across many different sites comprising the entire area (Figure 5.5-4).
Figure 5.5-1 Rural landscape of Pennsylvania
Areas already developed and urbanized are likely to define appropriate in-fill development and re-
development at higher densities. Multiple community planning sources with specific community
building standards and specifications are available for reference. The importance of careful
definition of growth zones and the performance standards that define these growth zones cannot be
overemphasized. Often this BMP has been driven by environmental conservation objectives such
as saving the undesirable growth areas (Sending Zones in TDR parlance) as discussed below but
every bit as much care must be taken in defining and planning the desirable growth areas
(Receiving Zones).
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Figure 5.5-2 Use of TDR to protect rural landscapes and direct development into the Town or Town Edge
Figure 5.5-3 Site clustering provides a partial open space network, though less than that provided by TDR
Figure 5.5-4 Large lot zoning ignores natural and cultural resource values.
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2. Defining Undesirable Growth Areas – Constraints: High Value Watershed Areas, Agricultural
Areas, Eco-Sensitive Habitat Areas, Headwaters, and Stream Designations
Criteria used by a municipality or area for managing development may be expected to vary to some
extent. Municipalities may include special watershed areas, which have Pennsylvania Code
Chapter 93 Special Protection Waters designation (Exceptional Value and High Quality), as well as
critical headwater (first order streams) portions of watersheds. Source Water Protection zones may
exist, including areas of especially important groundwater recharge, or habitat areas where the
Pennsylvania Natural Diversity Inventory (PNDI) indicates especially important species presence.
Also, important wetlands, floodplains and other natural features may exist. Prime Agricultural
Lands and Agricultural Security Districts may be deserving of conservation. Areas may be
especially sensitive due to rugged topography or steep slopes. Areas may be sensitive due to
richness of historical and archaeological and even scenic values. All of these important values are
likely to extend well beyond individual parcel boundaries and require smart growth area wide growth
management techniques.
3. Mixing and Matching Smart Growth Techniques: Public and Private
If a municipality consists of only a handful of enormous parcels where BMP 5.5.1 Clustering can
work together to achieve the areawide “desirable growth” and “undesirable growth” patterns for the
entire municipality as described above, BMP 5.5.2 would be made unnecessary. Such is usually
not the case. A municipality may decide to use all or most of the smart growth techniques
discussed here. A municipality may decide that “less is more” and try to achieve its objectives with
the most simple growth management program possible, using the fewest techniques. The blend of
public techniques versus private techniques is also important. Most of what is involved here entails
public sector management action, such as zoning ordinance provisions. A few municipalities in
Pennsylvania (West Marlborough, Chester County) have achieved municipality-wide success
through private landowner actions, such as voluntary donation of conservation easements to
conservancies and land trusts.
The optimal blend of smart growth techniques is not easily determined. Each technique has pros
and cons, in terms of technical effectiveness, ease of implementation, political and socioeconomic
implications, and integration with the local culture. Municipalities may decide to hire a local
planning consultant (contact the Pennsylvania Planning Association for additional references), or
may decide to consult with a free or low cost information resource such as the Pennsylvania
Environmental Council or 10,000 Friends of Pennsylvania. The direct state government agency
contact is the Pennsylvania Department of Community and Economic Development. These
organizations and agencies offer a variety of planning resources by providing information on smart
growth techniques and their potential usefulness in any one particular municipal setting. The
organizations’ respective websites should be consulted for more detailed information.
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Applications
Transfer of Development Rights (TDR)
Transfer of Development Rights (TDR, see Figure 5.5-5)
is allowed as an option in Pennsylvania under the
Municipalities Planning Code. TDR creates an overlay
(Sending Zone) in the zoning ordinance where property
owners are allowed to sell development rights for
properties where growth is deemed to be less than
desirable for any number of reasons. In a second
created overlay zone (Receiving Zone), these
development rights that have been purchased may be
used to increase development density, above the
maximum baseline or conventional zoned density. TDR
has been in existence for some years and has been u
by a relatively small number of Pennsylvania
municipalities, although it has been used more widely in
New Jersey and several other states. Although TDR is created in the municipal zoning ordinance, all
TDR transactions or transfers of development rights may occur within the private sector, between
Sending Zone owners and Receiving Zone purchasers or developers. TDR has been used in
Buckingham Township (Bucks County), West Bradford and West Vincent Townships (Chester County),
Manheim and Warwick Townships (Lancaster County).
sed
Figure 5.5-5 Example of Transfer of Development Rights
Growth Boundaries:
Growth Boundaries (Urban Growth Boundaries, see Figure 5.5-6) are based on the concept that
infrastructure such as public road systems and public water and wastewater treatment systems have a
powerful growth inducing and growth shaping influence
on an area wide basis. By controlling the location and
timing of this infrastructure through municipal or public
sector action, municipalities can encourage development
in certain areas and discourage development in others.
Growth Boundaries define where municipalities will
directly and indirectly encourage, and even provide
infrastructure services, significantly increasing zoned
densities. Areas lacking such infrastructure services are
zoned at significantly decreased densities. The State of
Oregon has been a leading advocate of Growth
Boundaries. Lancaster County for some years has been
applying Growth Boundary principles in its
comprehensive planning (go to their website to the
annual Growth Tracking reports which document how
their planning is achieving Growth Boundary objectives).
s been
applying Growth Boundary principles in its
comprehensive planning (go to their website to the
annual Growth Tracking reports which document how
their planning is achieving Growth Boundary objectives).
Effective Agricultural Zoning:
Effective Agricultural Zoning:
Large lot zoning (usually defined as zoning that requires average lot size to be greater than 2 acres per
lot) has been rejected by Pennsylvania courts as exclusionary and unacceptable. However, very large
minimum lot size to maintain existing agricultural uses has been deemed to be acceptable by
Pennsylvania courts and is being practiced throughout Pennsylvania, especially in intensive agricultural
communities in southcentral Pennsylvania (e.g., multiple municipalities in Adams, Berks, Chester,
Lancaster, York, etc.). Effective agricultural zoning may take the form of a specified mapped zoning
category with a minimum lot size of 10,15, 20, or 25 acres (this varies). Sliding scale agricultural
Large lot zoning (usually defined as zoning that requires average lot size to be greater than 2 acres per
lot) has been rejected by Pennsylvania courts as exclusionary and unacceptable. However, very large
minimum lot size to maintain existing agricultural uses has been deemed to be acceptable by
Pennsylvania courts and is being practiced throughout Pennsylvania, especially in intensive agricultural
communities in southcentral Pennsylvania (e.g., multiple municipalities in Adams, Berks, Chester,
Lancaster, York, etc.). Effective agricultural zoning may take the form of a specified mapped zoning
category with a minimum lot size of 10,15, 20, or 25 acres (this varies). Sliding scale agricultural
Figure 5.5-6 Example of Urban Growth Boundary
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zoning is a popular variation, where additional lots to be created and subdivided are a function of the
size of the total agricultural tract (though gross density remains very low). The intent is to allow a small
number of lots to be created over time, possibly for family members or for agricultural workers, but to
keep the functioning farms as intact as possible without residential subdivision or any other
development intrusion. The concept here is that the so-called “highest and best use of the land” is
agricultural use, which will be best maintained through protection of the farming community and through
this very low-density zoning. Application of Agricultural Zoning has been restricted to areas where
agriculture can be defined explicitly, typically in the presence of prime farmland soils, intensive
agricultural activity, formation of Agricultural Security Districts, or other indicators of important
agricultural activity. Obviously, this smart growth technique has limited application in terms of a growth
management technique.
Purchase of Development Rights:
Similar to TDR, the concept of Conservation Easements hinges on the notion that development rights
for any particular property can be defined and separated from a property. These development rights
can then be purchased and in a sense retired from the open market. The Pennsylvania Farmland
Preservation Program, which purchases development rights from existing agricultural owners and
allows farmers to continue their ownership and their agricultural activities, has become one of the most
successful agricultural preservation programs in the country. This program is highly competitive and
obviously limited to agricultural properties and contexts. The Farmland Preservation Program is a
priority of the current administration, will continue to be funded, and has been reinforced in several
counties with county-funded farmland preservation programs in order to stretch the state dollars.
Some counties (Bucks, Chester, Montgomery Counties) and municipalities (North Coventry, East
Bradford, Pennsbury, Solebury, West Vincent and others) have enacted special open space and
recreation acquisition programs. They are funded in various ways (bond issues, real estate taxes,
small payroll taxes) to purchase additional county-owned and municipality-owned lands, for use as
active and passive recreation as well as open space conservation. These efforts can be used in
conjunction with TDR programs, whereby a municipality funds a revolving fund-supported land
development bank which purchases development rights from vulnerable and high priority properties in
Sending Zones. It later sells these development rights (Warwick Township in Lancaster County has
done this) to Receiving Zone developers.
Conservation Easements (Donation and Purchase): Brandywine Conservancy, Natural Lands
Trust, Western Pennsylvania Conservancy, Others
Similar to TDR, the concept of Conservation Easements hinges on the notion that development rights
for any particular property can be defined and separated from a property. These development rights
can then be donated to an acceptable organization to support the public’s health, safety and welfare, in
the form of a conservation easement which restricts the owner’s ability to develop the property in
perpetuity, regardless of municipal zoning. Historically, a major incentive for these conservation
easement donations has been the major tax benefits afforded such donations. Organizations such as
the Brandywine Conservancy, Natural Lands Trust, the Western Pennsylvania conservancy and many
others have protected thousands of acres of otherwise developable property in Pennsylvania through
privately donated conservation easements, with absolutely no public expenditure of funds.
Brandywine’s 30,000 acres of conservation easements in the Brandywine Creek Watershed is an
excellent case in point. Municipalities such as West Marlborough Township in Chester County have
large portions of their jurisdictions permanently conserved as the result of this Conservation Easement
program. Conservation Easements also can be purchased by a conservation organization or
government agency. National organizations such as the Nature Conservancy, the Trust for Public
Land, the Land Trust Alliance, and others are active in Pennsylvania and are excellent sources of
technical information relating to this smart growth technique. In parts of Pennsylvania, these larger
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organizations are helping fledgling local land trusts form and begin their important work of land
conservation.
Bargain Sale/Limited Development Options:
A variation on the donation of development rights through conservation easements is a “bargain sale,”
where a portion of the development rights value is donated (in the manner described above) but the
property owner still enjoys a return on his/her property. In any number of development-pressured
municipalities in Pennsylvania, fair market value for a large 100-acre farm to be developed as single-
family residences or some other use may reach 2 or 3 million dollars. The owner, beyond tax benefits,
may need a monetary settlement, though not in the order of 2 to 3 million dollars. In such cases, a
defined “bargain sale” might be arranged if a source of funds can be located to provide a partial
financial settlement for the owner. The owner benefits from an approved donation of the remainder of
the value that can reduce the owner’s tax bill. The property is conserved.
A further variation would be a limited development option wherein a substantially reduced development
program is developed which conserves much if not most of the property in question. An existing
farmstead or homestead is retained and the property owner may even retain this farmstead/homestead.
A much smaller number of lots surrounded by open space is carefully created; these lots typically
command a considerably higher value than would be the case for a conventional subdivision. A large
amount of open space is created and protected through a conservation easement, which may be
donated as well, providing further tax benefit. The outcome is that the property owner, after taxes, may
be almost as well off after a Limited Development approach to the property than would be the case with
a complete conventional “as of right” approach to development. If the Limited Development concept
has been prepared carefully, total property disturbance can be substantially reduced.
Sustainable Watershed Management and Water-Based Zoning: Green Valleys Association and
the Brandywine Conservancy
Design Considerations:
Objectives for BMP 5.5.2 resemble BMP 5.5.1, although they must be understood as municipality-wide,
rather than just site-wide:
Maximize open space, especially sensitive areas (primary and secondary) and areas of
special value.
Maximize “sense of place” design qualities where growth is desirable.
Balance infrastructure needs (sewer, water, roads, etc.) and use infrastructure to shape
desirable growth
BMP 5.5.2 relies on application of smart growth techniques. The specific optimal blend of these smart
growth techniques should respond to a variety of municipality characteristics and considerations. This
BMP discussion assumes that proper and effective work has been undertaken by the municipality to
determine the proper land uses and the proper densities/intensities of these land uses, municipality-
wide. The question is then: how can these uses – this future development - be best planned within the
municipality, achieving the best and most livable communities for the future, even as disruption to the
natural landscape is minimized?
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Detailed Stormwater Functions
Concentrating growth, as defined here, is self-reinforcing from a stormwater management perspective –
in terms of peak rate reduction, runoff volume reduction, and nonpoint source load reduction.
Concentrating growth reduces total impervious areas and is likely to link with other BMP’s in this
Section, including reduced imperviousness, reduced setbacks, reduced areas for drives and walkways,
etc. All of this directly translates into reduced volumes of stormwater being generated and reduced
peak rates of stormwater being generated, thereby benefiting stormwater planning. Additionally,
concentrating growth translates into reduced disturbance and increased preservation of the natural
landscape and natural vegetative land cover, which further translates into reduced stormwater runoff.
To the extent that this BMP also involves increased vertical development, net site roof area and
impervious area is reduced, holding number of units and amount of square footage of a use constant.
In all cases, density bonuses, if utilized in Receiving Zones, should be scrutinized to make sure that
additional density allowed is more than balanced by additional open space being provided, including
further reductions in street lengths, other impervious surfaces, other disturbed areas, and so forth. If
properly implemented, these smart growth techniques such as TDR and Growth Boundaries will almost
always translate into reduced total disturbed area and reduced total impervious area, even more
dramatically than non-structural techniques such as clustering.
Documentation of the positive water quality effects of area wide growth concentration, holding total
growth and development constant, is provided by the City of Olympia’s (Washington)
Impervious
Surface Reduction Study: Final Report 1995
. Holding population projected to 2015 constant, two
dramatically different scenarios of land development (a baseline pattern of low density unconcentrated
development reflecting recent development trends versus a concentrated pattern of increased density
development in and near existing developed areas) were defined. These were mapped (Figure 5.5-7)
and tested for a variety of stormwater-related impacts (total impervious area, total disturbed area,
stormwater generation, non-point source pollutant generation). The analysis results indicated that the
concentrated development scenario significantly reduced total impervious area. This was due to
significant reductions in impervious
surfaces being created in outlying r
and low density areas and more
efficient utilization of impervious
surfaces already created in areas of
existing development. Other studies
focusing on concentrated growth
patterns have similarly confirmed
these relationships and further
documented a reduction in total
disturbed areas created, stormwater
being generated, and total non-point
source pollutant loads being
generated.
and low density areas and more
efficient utilization of impervious
surfaces already created in areas of
existing development. Other studies
focusing on concentrated growth
patterns have similarly confirmed
these relationships and further
documented a reduction in total
disturbed areas created, stormwater
being generated, and total non-point
source pollutant loads being
generated.
ural
As stated above in BMP 5.5.1, water
quality issues include all the non-point
source pollutant load from impervious
areas, a well as all the pollutant load from the newly created maintained landscape (i.e., lawns and
other), much of which is soluble in form (especially fertilizer-linked nitrogen forms). Concentrating
growth as defined in BMP 5.5.2, and combined with other Chapter 5 Non-Structural BMP’s, minimizes
impervious areas and the pollutant loads related to these impervious areas. After Chapter 5 BMP’s are
optimized, “unavoidable” stormwater is then directed into BMP’s as set forth in Chapter 6, to be
As stated above in BMP 5.5.1, water
quality issues include all the non-point
source pollutant load from impervious
areas, a well as all the pollutant load from the newly created maintained landscape (i.e., lawns and
other), much of which is soluble in form (especially fertilizer-linked nitrogen forms). Concentrating
growth as defined in BMP 5.5.2, and combined with other Chapter 5 Non-Structural BMP’s, minimizes
impervious areas and the pollutant loads related to these impervious areas. After Chapter 5 BMP’s are
optimized, “unavoidable” stormwater is then directed into BMP’s as set forth in Chapter 6, to be
Figure 5.5-7 Dispersed versus Concentrated Development at the Regional Scale,
(Source: “Impervious Surface Reduction Study”, City of Olympia, 1995)
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properly treated. Similarly, for all that non-point source pollutant load generated from the newly-created
maintained landscape and combined with other Chapter 5 Non-Structural BMP’s, minimizes pervious
areas and the pollutant loads related to these pervious areas, thereby reducing the opportunity for
fertilization and other chemical application. Prevention of water quality degradation accomplished
through Non-Structural BMP’s in Chapter 5 is especially important because Chapter 6 Structural BMP’s
remain poor performers in terms of mitigating/removing soluble pollutants that are especially
problematic in terms of this pervious maintained landscape. See Appendix A for additional
documentation of the water quality benefits of clustering.
See Chapter 8 for additional volume reduction calculation work sheets, additional peak rate reduction
calculation work sheets, and additional water quality mitigation work sheets.
Construction Sequence
Application of this BMP must be undertaken by the municipality and must precede the start of any
individual site planning and development process. In most cases, the municipality must take action in
its comprehensive plan and then in its zoning and SLDO to incorporate the optimal blend of these smart
growth techniques in their respective municipal planning and growth management program (the
proactive municipality may act further to program for use of conservation easements, creation of a local
land trust, and the like). At the same time, the site owner/builder/developer may elect to embrace
options set forth in BMP 5.5.2 Concentrate Uses Area wide from the start of the process. Use of
conservation easement donation, bargain sale or limited development all require careful consideration
by the site owner/builder/developer from the beginning of the site development process.
Maintenance Issues
Very few maintenance problems or issues are generated by BMP 5.5.2. Because most of these smart
growth techniques are preventive in nature and in fact translate into maximum retention of undisturbed
open space and the natural features contained within this open space, typically in private ownership,
specific maintenance requirements as defined in a conventional manner are extremely limited, if not
nonexistent.
Cost Issues
According to Delaware’s recent
Conservation Design for Stormwater Management: A Design Approach
to Reduce Stormwater Impacts from Land Development
, application of the municipality-wide or
areawide smart growth techniques will require some additional costs. Application of an optional TDR
program or Growth Boundary program could cost a municipality in technical planning fees, including
incorporation into the comprehensive plan and zoning ordinance (other costs may be required as well).
Although it is hard to specifically document, a program of structural BMP’s which mitigate adverse
impacts of land development and achieve the same level of water resource (quantity and quality)
performance throughout the municipality and its respective watershed areas becomes much more
difficult to achieve, and much more expensive when all development and all lots are tallied. Prevention
is simply much more cost effective.
Furthermore, BMP 5.5.2’s preventive smart growth techniques, when fully applied, achieve a level of
performance that exceed even the best structural BMP’s. This clearly demonstrates why non-structural
BMP’s are important for all Pennsylvania watersheds, but especially important for Special Protection
Waters where High Quality and Exceptional Value designations call for extremely high levels of water
resource protection. In these cases, significant amounts of development watershed-wide, even
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assuming use of Chapter 6 structural BMP’s, may fail to provide the water resource protection which is
needed to sustain special Protection Waters’ values over the long-term.
Specifications
BMP 5.5.2 is not a new concept and has been defined, discussed, and evaluated in many different
texts, reports, references, sources, as set forth below. More specifications for clustering can be found
in references that are included in above discussions.
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