Clustered subdivisions are not permitted in the RR1 or RR2 zoning districts. Clustered subdivisions are residential developments in which groups or clusters of dwelling units may be located on adjoining individual building lots which may be smaller than the required minimum lot size for the zoning district in which they are located but within which land is set aside as common open space, so long as the maximum number of lots permitted shall not exceed that allowed per the underlying zoning district. The following standards apply to development in clustered subdivisions in place of the otherwise applicable dimensional requirements for the zoning district in which the development is located:
A. 
Lot density calculation.
(1) 
Net residential acreage. The net residential acreage shall be calculated as defined.
(2) 
Maximum number of lots allowed. The maximum number of lots allowed in a clustered subdivision shall be calculated by dividing the net residential acreage by the minimum lot size allowed in the applicable zoning district (net residential acreage/minimum lot size allowed in zoning district = maximum number of lots allowed).
B. 
Minimum lot size. If the lots are connected to the public water and sewer systems, the minimum lot size for each single-family dwelling shall be 30,000 square feet and for each duplex dwelling shall be 40,000 square feet. If the lots are connected to the public water system but not the public sewer system, the minimum lot size for each single-family dwelling shall be 45,000 square feet and 60,000 square feet for each duplex. If the lots are not connected to the public water and sewer system, the minimum lot size for each single-family dwelling shall be 60,000 square feet and for each duplex dwelling shall be 80,000 square feet.
C. 
Lot setbacks.
(1) 
Setback requirements for a clustered subdivision shall be the same as those required in the zoning district in which the subdivision is located.
(2) 
Sheds and driveways are permitted a minimum setback of 15 feet from the side and rear lot lines.
D. 
Frontage. Each lot shall have no less than 75 feet of lot frontage on a street.
E. 
Buffer. A buffer of at least 75 feet in width shall be created around the entire perimeter of the subdivision. For subdivisions that front on Tuttle, Greely, Blanchard, and Foreside Road, the buffer along those roads shall be 150 feet. Where possible, existing trees and vegetation shall be preserved in buffers, except that vegetation classified as invasive may be removed.
A. 
At least 25% of the total area of the tract or parcel of land being developed must be maintained as common open space and not included in the individual building lots. Common open space may include, but not be limited to, the following:
(1) 
Active farmland or land adjoining active farmland;
(2) 
An active trail system or which provides a link to an existing trail system;
(3) 
Land which provides a buffer around a sensitive wildlife habitat or other natural area;
(4) 
Land which provides physical or visual access to a water body, including the ocean, lake, pond, river, stream, or brook;
(5) 
Land in a Resource Protection District as shown on the official Town of Cumberland Overlay Map;
(6) 
Land which is suitable for active or passive recreation; and
(7) 
Land which abuts or adjoins an existing public open space.
B. 
Ownership, management, legal protection, and maintenance of common open space in a clustered subdivision.
(1) 
Ownership of common open space. The applicant must identify who will be the owner of the common open space and who will be responsible for maintaining the common open space and facilities located thereon if that will be someone other than the owner of the common open space. If a homeowners association will be the owner, membership in the association must be mandatory and will be required by deed covenants for all homeowners in the subdivision and their successors. If a homeowners association is the owner, it must have lien authority to ensure the collection of assessments from all members. The cost and responsibility for maintaining the common open space and any facilities located thereon shall be borne by the owner.
(2) 
Management of common open space. The applicant must submit a plan for management of common open space and common facilities that:
(a) 
Allocates responsibility and standards for the maintenance of the common open space and any facilities located thereon, including provisions for ongoing maintenance and for any required long-term capital improvements;
(b) 
Estimates the costs and staffing requirements needed for maintenance and operation of, and insurance for the common open space and outlines the means by which such funding will be obtained or provided;
(c) 
Provides that any changes to the plan must be approved by the Planning Board; and
(d) 
Provides for the enforcement of the plan.
(3) 
Legal instrument for protection of common open space. The common open space must be protected by a binding legal instrument that is recorded with the deed. The instrument must be a permanent conservation easement held by one of the following:
(a) 
A land trust or similar conservation-oriented nonprofit organization with legal authority to accept such easements. The nonprofit organization must be in good legal standing and the conveyance instruments must contain all appropriate provisions for retransfer in the event the organization becomes unable or chooses to not carry out its functions.
(b) 
A governmental entity with the authority to pursue goals compatible with the purposes of this chapter. If the entity accepting the easement is not the Town, then a third-party right of enforcement granted to the Town may be included in the easement.
(c) 
A permanent restrictive covenant for conservation purposes granted to a governmental entity.
(d) 
An equivalent legal tool, if approved by the Town Attorney and Planning Board, that provides permanent protection such as a homeowners association.
(e) 
The instrument of permanent protection must include clear restrictions on the use of common open space and must include all restrictions contained in this chapter, as well as any further restrictions the applicant chooses to place on the use of the common open space. All legal instruments provided shall be subject to review by the Town for compliance with the requirements of this chapter.
(f) 
The common open space within an approved clustered subdivision is the responsibility of the owner(s), regardless of whether or not the land is leased to another entity. Maintenance requirements and restrictions must be listed and approved by the Planning Board as part of the conditions of approval.
(4) 
Additional common open space considerations:
(a) 
Utility rights-of-way and areas of impervious surface may be included within the protected common open space but cannot be counted towards the 25% minimum area requirement (exception: historic structures and existing trails may be counted).
(b) 
Where possible, common open space areas shall be contiguous to another common open space area either within or abutting the subdivision. The common open space should adjoin any neighboring areas of open space, other protected areas, and nonprotected natural areas that would be candidates for inclusion as part of future protected open space.
(c) 
All lots must be provided with safe, convenient access to the common open space. The minimum width of an access easement to the common open space is 10 feet.
(d) 
The applicant shall be responsible for its maintenance until at least 75% of the lots have been sold to individual lot owners, after which time the homeowners association shall be responsible for such maintenance, and this requirement shall be set forth in the deed covenants or other legal instruments binding upon the lot owner and running with the land.
(e) 
The Planning Board may require the developer to dedicate easements not less than 10 feet wide to the Town over any existing trails that are observable during the site walk or are shown on existing conditions maps. If the location of the existing trails precludes the appropriate placement of house lots or infrastructure, the trail may, with the approval of the Planning Board, be relocated on the parcel. This provision shall only apply to trails which connect to trails on adjacent properties. Where an easement is dedicated to and accepted by the Town, the Town shall have the right but not the obligation to maintain such easements. Any such dedication must be made through appropriate legal instruments approved by the Town Attorney.