slope protection ordinance - with changes from last land use committee — File 207122

Submitted by Ward 5 Alderman Mark Niedergang Date: August 22, 2018 Slope Protection Amendment to the Somerville Zoning Ordinance to require a special permit for developments on steeply sloped parcels A. Purpose. (1) The purposes of this section shall be: (a) To preserve and enhance the landscape by encouraging the maximum retention of natural topographic features, such as drainage swales, streams, slopes, ridge lines, rock outcroppings, vistas, natural plant formations and trees; (b) To minimize the effects of grading to ensure that the natural character of steep slopes is retained; (c) To minimize water runoff and soil erosion problems incurred in grading of steep slopes; and (d) To encourage innovative architectural, landscaping, circulation and site design; [e] To help protect structures and properties at the base of a slope below construction from damage from erosion, mudslides, rockslides, falling trees, and other harms. (2) For the purposes of this section, the term "natural" shall be defined as the condition of the ground surface as it exists on the date this section is adopted. No land may be regraded or filled in such manner as to circumvent this section. B. Applicability. (1) The provisions of this section shall be applicable to all zoning

districts in the City of Somerville. Exempted from this section shall be: (a) Alterations, extensions, and additions to existing single- and two- family dwellings and any buildings accessory thereto that do not expand the building footprint by more than 250 square feet. (b) Site improvements to existing single- and two-family dwellings any lot that do not exceed 500 square feet. (2) The provisions of this section shall not apply to a development which has received a building permit from the Inspectional Services Department (ISD) prior to the time the notice of this amendment was published. C. Use and dimensional regulations. The slope of land at any point, stated as a percentage, shall be defined as the change in elevation over a horizontal distance multiplied by 100: slope = (change in elevation ± / horizontal distance measured perpendicular to horizon) x 100. (1) All natural slopes exceeding 25% over a horizontal distance of 30 feet are protected and shall remain in their natural state. All development on any lot with a slope of 25% or greater over a horizontal distance of 30 feet or greater requires a Special Permit. D. Special Permit. The Special Permit Granting Authority (SPGA) may grant a special permit to utilize areas with natural slopes exceeding 25%, as prohibited in Subsection C(1), if the SPGA finds that the proposal satisfies the purposes set forth in Subsection A(1)(a) through (e) above as well as all the findings required for granting a Special Permit under all other relevant sections of the Somerville Zoning Ordinance. (1) Applications.
(a) Applications for a special permit shall include the following:

[1] An executive summary and site plan generally describing the nature and location of the project and how it fulfills the purpose of this section and meets the requirements for issuance of a special permit under all other relevant sections of the Somerville Zoning Ordinance; [2] Parcel lot lines for the proposed project and surrounding parcels; [3] Location of existing and proposed buildings on the project site; [4] Foundation lines of the proposed buildings, gross floor area, and building height; [5] Existing and proposed topography and the location of all natural features such as wetlands, streams, water bodies, and exposed bedrock to be removed, if any; [6] Areas subject to a one-hundred-year flood, if any; [7] Provisions for the protection of abutting properties during construction, and site excavation, demolition, blasting, and site reclamation plans if appropriate; [8] Proposed landscaping, including all screening and buffering of adjacent residential areas; [9] An erosion prevention plan prepared by a registered/licensed professional, which includes calculations and measures to prevent erosion and undermining of the subject property and abutting properties. Include how slope protection will be achieved and details of all retaining walls if applicable; [10] Drainage calculations prepared by a registered/licensed engineer demonstrating that following the proposed removal, the amount of runoff shall not exceed the amount of runoff prior to the removal;

[11] A stormwater management plan and installation of underground and surface drainage facilities in accordance with best management practices to prevent surface erosion, undermining, and post-development runoff that exceeds pre-development runoff; and [12] Any other information requested by the Special Permit Granting Authority (SPGA) that will allow fair and full consideration of the special permit request. (b) Any of the requirements of a slope protection special permit application may be waived by a majority vote of the SPGA. Waiver requests must be in writing. (2) The Planning Department in the Office of Strategic Planning and Community Development (OSPCD) will distribute a set of the application materials to the City Engineer and Building Inspector (Inspectional Services Department) for review. OSPCD will provide notice of receipt of an application to the Board of Health, Fire Chief, Police Chief, Conservation Commission, Department of Public Works, Traffic and Parking Department, City Solicitor, and Mayor. All departments shall report their comments, conditions, remedial measures and recommendations, in writing, to the SPGA within 60 days. E. Special Permit Granting Authority. For slope protection special permits the Zoning Board of Appeals is the SPGA unless the application must go before the Planning Board for other reasons, in which case the Planning Board is the SPGA. F. Relationship to site plan review. For the convenience of the applicant, site plan review and request for a special permit pursuant to this section may be acted upon concurrently to the degree feasible. The applicant will be responsible for submitting a request which meets all submission requirements, concurrently, in order to streamline notice and hearing requirements.