A.
Purpose.
1.
The site capacity analysis provides the mechanism for subtracting from the base site area all portions of a site inappropriate for development due to the presence of sensitive environmental resources or land features. Consequently, the purpose of this section is to determine the extent to which a site may be utilized given its unique physical characteristics.
2.
The site capacity analysis required by this section provides a logical and rational basis for:
(a)
Establishing the intensity of development in relation to the natural capabilities of the land to sustain disturbance without incurring significant disruption of the sensitive natural resources and features of the Township; and
(b)
Protecting persons and property from hazards resulting from the inappropriate development of land containing sensitive, unstable or hazardous natural resources or features.
B.
Applicability.
1.
In the Conservation Residential (CR), Suburban Residential (SR), and Medium-Density Residential (MDR) zoning districts, those uses listed below shall submit a base site area calculation in accordance with this section, as a condition of approval of any land development plan, plan of subdivision or building permit required under this chapter.
2.
The resource protection land calculations and determination of site capacity required by this article shall apply and be submitted in the following instances:
(a)
Any major subdivision, or manufactured home community within the Conservation Residential (CR), Suburban Residential (SR) and Medium-Density Residential (MDR) zoning districts, that is not developed as a conservation subdivision.
(b)
Land development consisting of five or more dwelling units in the Conservation Residential (CR), Suburban Residential (SR) and Medium-Density Residential (MDR) zoning districts, that is not developed as a conservation subdivision.
(c)
Non-residential conditional uses permitted in CR, SR and MDR zoning districts.
3.
Resource protection land may be either located in open space and outside of lot areas or may be placed in conservation easements within the lot area.
4.
Standards for location and management shall be as follows:
(a)
All conservation easements shall be identified on the property;
(b)
The developer shall identify on each conservation easement all resources that are protected in said easement;
(c)
The developer, on the plan, shall provide, in writing on the plan, that the resources protected within the conservation easement shall not be disturbed;
(d)
The developer shall, in writing on the plan, grant and convey the conservation easements to all lot owners of the plan and/or homeowners' association properly created;
(e)
The grant of easement shall be forever;
(f)
The easement granted shall be for the conservation of all resources identified within the easement which shall not be disturbed;
(g)
The conservation easement granted to the lot owners or homeowners' association shall not be saleable, assignable or transferable without the consent of the Board of Supervisors of Marshall Township. Any sale, assignment or transfer of the conservation easements shall require the consent of two-thirds (2/3) of all lot owners in the plan;
(h)
The developer shall grant to the lot owners or the homeowners' association the right to maintain said easement and to do so the right to traverse by foot or vehicle over any lot to maintain said easement. Any damage caused to any lot in maintaining the easement shall be repaired at the expense of the lot owners or homeowners' association;
(i)
All deeds for lots that contain conservation easements shall, in a conspicuous location, have language identifying the conservation easement and advising the purchaser of the lot that the resources contained in the conservation easement shall be undisturbed. The deed shall further contain language identifying that the lot owners or homeowners' association have a right to traverse over the purchaser's lot to maintain the easement;
(j)
In the event that the organization established to maintain the conservation easement or any successor organization shall, at any time after establishment of the development, fail to maintain the conservation easement in reasonable order and condition, the Board of Supervisors may proceed to demand that the deficiencies in maintenance be corrected or that the Township will enter upon and maintain the conservation easement. Notice to the property owners shall set forth the manner in which the organization has failed to maintain the conservation easement, and said notice shall include a demand that such deficiencies of maintenance be corrected within 30 days, the notice shall state that the property owners or homeowners' association may, within 14 days of the notice, request a hearing before the Board of Supervisors. The cost of such maintenance by the Township shall be assessed ratably against the properties within the development and shall become a lien on said properties. The Township at the time of entering upon said conservation easement, for the purpose of maintenance, shall file a notice of lien in the office of the Prothonotary of Allegheny County upon the properties within the development;
(k)
All of the above requirements shall be included in writing on the plan and given to any prospective lot purchaser.
C.
Relationship of zoning district standards to site capacity analysis. All developments shall comply with the standards set out in the applicable zoning district governing the maximum density, maximum floor area, maximum impervious surface, minimum lot areas and width requirements and minimum open space requirements specified for each zoning district. In the case of residential uses, site capacity for any proposed development is equal to the net buildable area of the site multiplied by the density factor. The site capacity calculation provides the mechanism for subtracting from the base site area all portions of a site that are inappropriate for development.
D.
Base site area calculations.
1.
The first step in the determination of the site capacity is to establish the base site area. If site capacity analysis is required, the following calculations shall be submitted:
Table 6: Base Site Area | |
|---|---|
1. Gross site area as determined by actual on-site survey: | _____ acres |
2. Subtract land constituting existing or future street rights-of-way, easement of access, or area set aside for public or private utilities, stormwater facilities and easements: | _____ acres |
3. Subtract land which is not contiguous: | |
(a) A separate parcel which does not abut, adjoin or share common boundaries with the rest of the development: | _____ acres |
(b) Land which is cut off from the main parcel by a road, railroad, existing land uses or major stream so that common use is hindered or the land is unavailable for building purposes: | _____ acres |
4. Subtract land that in a previously approved subdivision encompassing the same land, which as part or all of the subject parcel, was reserved for resource protection reasons (e.g., flooding): | _____ acres |
5. Subtract land required for buffer planting strip pursuant to § 208-503 of this chapter. Do not subtract buffer planting strip areas where they contain resource protection land. To determine the amount of resource protection land in the buffer planting strip, a similar table as that in Subsection E shall be used. Column 3 shall be labeled "Acres of Resource Land in Buffer Planting Strip" and column 4 shall be labeled "Resource Protection Land in Buffer Planting Strip": | _____ acres |
6. Equals base site area: | _____ acres |
E.
Resource protection land calculations.
1.
One of the principal factors that will influence the intensity of development on a particular parcel of land is the requirement for protecting the designated environmental resources existing on the site. Specific natural resources that are sensitive to development, such as woodland, steep slopes, floodplains and streams, are protected within this article. All land area consisting of the natural resources or natural features listed in the following table shall be mapped and quantified by the developer as part of the site development plan review process. The resource protection land shall be calculated in the following manner:
(a)
Calculate the total area (acreage) of each natural resource.
(b)
Multiply the total area of each resource by the preservation ratio for that resource to determine the amount of resource protection land required to be kept in open space or conservation easements in order to protect the resource or feature.
(c)
On that portion of the site where two or more resources overlap, only that natural resource which has the highest preservation ratio shall be calculated.
(d)
All resource protection land must be preserved by either open space or conservation easements. All resource protection land for woodland, wetlands and floodplains must be located in open space and outside of lot areas.
Table 7: Resource Protection Calculation | |||
|---|---|---|---|
Resources/Natural Features (all districts) | Preservation Ratio | Acres of Land in Resource | Resource Protection Land (acres in resource × preservation ratio) |
Drainageways | 0.50 | __________ | __________ |
Floodplains | 1.00 | __________ | __________ |
Wetlands | 1.00 | __________ | __________ |
Woodland | 0.45 | __________ | __________ |
Steep slopes (15% to 25%) | 0.40 | __________ | __________ |
Steep slopes (greater than 25%) | 0.80 | __________ | __________ |
Total land in resource | __________ | __________ | |
Total resource protection land | __________ | ||
F.
Determination of site capacity (all residential land uses). Individual site capacity is determined by calculating the net buildable site area. For residential developments, the number of dwelling units permitted is determined by multiplying the net density factor by the net buildable site area. Net density factors and district preservation ratios for residential districts are provided in § 208-207. The calculations are as follows:
G.
Density factors and open space ratios for residential districts shall be as follows:
Table 9: Residential Performance Standards For Residential Districts1 | |
|---|---|
District | Maximum Density |
Conservation Residential (CR) | 1 |
Suburban Residential (SR) | 2 |
Medium-Density Residential (MDR) | |
Single-family semi-attached | 4 |
Townhouses | 8 |
Apartments | 10 |
Notes: |
1 All density figures shown are expressed in units per acre unless otherwise noted. |
H.
Natural resource or environmental protection standards.
1.
On that portion of the site where two or more resources overlap, only that natural resource which has the highest preservation ratio shall be calculated by the following standards. The following standards refer to the same mapped portions of each resource as determined by Subsection E.
(b)
Steep slopes. In areas of steep slopes, the following standards will apply:
(i)
A 15% to 25% slope: no more than 60% of such areas shall be developed and/or regraded or stripped of vegetation.
(ii)
More than 25% slope: no more than 20% of such areas shall be developed and/or regraded or stripped of vegetation.
Slope Grade Percent | % of Developable Slope |
|---|---|
15% – 25% | Up to 60% of slope area |
>25% | No more than 20% of slope area |
(c)
Drainageways. No more than 50% of such areas may be developed.
(d)
Existing vegetation. Existing, healthy plant material may be counted as contributing to the total plant material required by the landscaping and buffer planting strip requirements of this chapter, except in the case of establishment of new woodland. Whenever an existing area meets the definition of woodland, it shall satisfy any planting required by this chapter, regardless of the mix of plant materials, provided that understory trees and shrubs constitute at least 70% of the individual trees and shrubs present. If understory trees and shrubs constitute less than 70% of the trees and shrubs present, additional plant material shall be installed in order to meet the requirements otherwise imposed. No tree greater than five-inch caliper shall be counted if more than one-eighth (1/8 ) of the area under its canopy or dripline is less than 15 feet from a building, parking area or road.
Table 10: Required Tree Sizes | |
|---|---|
30 slower growing canopy trees | 5 feet high |
10 understory trees | 1-inch caliper |
100 shrubs | 3 feet high |
(i)
All new plant materials shall meet the requirements set forth in the American Standard for Nursery Stock, published by the American Association of Nurserymen, ANSI 260.1, latest edition. All existing healthy trees shall be preserved to the maximum extent possible.
(ii)
All areas of a newly established woodland shall be mulched and/or seeded as lawn unless ground cover is to be established and maintained.
(iii)
In maintaining newly established woodland areas, additional plants established by natural succession shall be retained. Dead trees shall be removed where they adjoin roads or buildings, but otherwise left alone and felled and left at the site. Debris and litter shall be cleaned on an annual or semiannual basis. Damage to 15% or more of the stand due to disease, wind or fire within a period of two years from their installation shall require the replacement of all such damaged trees.
(e)
Floodplains: 100% of the floodplains must be maintained in open space.
(f)
Wetlands: 100% of the wetlands must be maintained in open space.
(g)
A land disturbance map shall be submitted for each natural resource on the site that denotes the required preservation area.

