05.11.23 CC Amend Zoning Vegetated Roofs — File 23-0791

CITY OF SOMERVILLE ORDINANCE NO. 2023- IN CITY COUNCIL: ________, 2023 Be it ordained by the City Council, in session assembled, that sections 10.3 and 10.4.1 of the Zoning Ordinances of the City of Somerville are amended as follows by deleting the struckthrough text and adding the underlined text. Approved: President Approved: Mayor

451 SOMERVILLE ZONING ORDINANCE | 05/01/23 10. Development Standards Landscaping b. Perimeter Planting i. Surface parking must be screened from view along any lot line abutting a public thoroughfare, excluding and alley, by a landscape buffer designed in accordance with §10.3.6 Landscape Buffers. c. Landscape Islands i. A landscape island must be provided every five (5) parking spaces and at the end of every row of parking spaces. ii. Landscape islands may be consolidated and intervals may be adjusted as necessary to preserve existing trees or facilitate storm water management. iii. Landscape islands abutting a single row of parking spaces must be at least eight (8) feet in width and the same length as the parking spaces. Each island must include one (1) large tree. iv. Landscape islands abutting a double row of parking spaces must be at least eight (8) feet in width and the same length as the parking spaces. Each island must include two (2) large trees. 8. Vegetated Roofs a. Construction of a new principal building or the substantial renovation of an existing principal building in the Mid-Rise, High-Rise, or Commercial zoning districts must include a vegetated roof for eighty percent (80%) of the available roof area. i. Roof area for mechanical or stairwell penthouses; roof mounted cellular, radio, and internet transmission equipment; vents or exhausts; and photovoltaic (PV) devices is exempt. ii. Roof area for required open space or outdoor amenity space is exempt. iii. Non-habitable architectural features, required screening, and unobstructed areas required by the Massachusetts State Building Code are exempt. iv. Development subject to the Affordable Housing overlay district is exempt.

452 | SOMERVILLE ZONING ORDINANCE 05/01/23 10. Development Standards Green Score 10.4 GREEN SCORE 1. Purpose a. To incentive urban landscape elements that manage storm water, filter pollutants, reduce the urban heat island, provide habitat, sequester carbon dioxide, and improve air quality. 2. Overview a. Green score is an environmental sustainability performance standard for urban landscapes. b. Green Score is measured as the combined weighted value of all landscape elements to divided by the total land area of a lot. c. Landscaped areas that earn a higher green score correlate to a higher environmental sustainability than sites that earn a lower score. 3. Applicability a. This section is applicable to the construction of any new principal building and any substantial renovation of a principal building. 4. Compliance & Enforcement a. Real property must comply with the Green Score indicated for each building type. See the standards for each building type in each zoning district for more information. b. The Building Official shall establish standards for the administration of this Section. 5. Calculation a. Green Score is calculated as follows: i. Determine total lot area. ii. Calculate the area of each proposed landscape element for each category identified in the first column of Table 10.4.1. Certain types of plantings use the number of individual plants multiplied by an equivalent square footage when indicated in the second column of Table 10.4.1. iii. Multiply the actual square footage, or the equivalent square footage, of each landscape element by the multiplier specified for each landscape element in the third column of Table 10.4.1 plus any bonus on Table 10.4.2 to determine the weighted score of each element. iv. Add the weighted score of all landscape elements together. v. Divide the resulting sum by the area of the lot to determine the final Green Score. vi. If necessary, redesign the landscape plan to achieve the required Green Score. b. Bonuses i. Review Boards may establish additional bonuses Table 10.4.1  Green Score Calculation Credit Multiplier Soils Landscaped area with a soil depth < 24 inches actual sf 0.3 Landscaped area with a soil depth => 24 inches actual sf 0.6 Pervious Paving with 6 to 24 inches of subsurface soil or gravel actual sf 0.2 Pervious Paving with more than 24 inches of subsurface soil or gravel actual sf 0.5 Groundcovers Turfgrass, mulch, and inorganic surfacing materials actual sf 0.1 Plants Vegetation less than two (2) feet tall at maturity actual sf 0.2 Vegetation at least two (2) feet tall at maturity 12 sf/plant 0.3 Trees Small Tree 50 sf/tree 0.6 Large Tree 450 sf/tree 0.6 Preserved Tree 65 sf/tree 0.8 Engineered Landscape Vegetated Wall actual sf 0.1 Rain gardens, bioswales, and storm water planters. actual sf 1.0 Green Vegetated roof with up to 6” of growth medium actual sf 0.1 Green Vegetated roof with 6”-10” of growth medium actual sf 0.4 Green Vegetated roof of 10”- 24” growth medium actual sf 0.6 Green Vegetated roof of over 24” growth medium -- per individual landscape elements