Green Infrastructure Digest

This month, the topic of APA’s Planning Advisory Service’s column, “You Asked, We Answered”, is how zoning codes across the country are handling pervious pavement for parking and sidewalks. The links to the various zoning codes were very useful. The following are excerpts from some of the more interesting ones.

ASHEVILLE, NC

“Porous paving blocks and pervious paving materials are permitted and encouraged as material for parking lots. The use of grass as a parking lot surface is permitted for overflow and intermittent parking. Pervious paving systems are required for parking spaces which exceed the maximum number of spaces required by subsection 7-11-2(c). The use of grass or other vegetation as a parking surface is permitted only for parking spaces which are provided in excess of the maximum number of parking spaces required by subsection 7-11-2(c) or used for intermittent or overflow parking. Parking lots associated with arenas, sporting facilities, amphitheaters, fairgrounds, and religious institutions may, however, use grass or other vegetation for the entire parking lot.”

DOUGLAS COUNTY, MN

Impervious Surface Replacement. Existing properties exceeding the standards for impervious surface coverage present a distinct management challenge from that of newly developed properties and there is a need to establish clear and consistent guidelines for how re-development of these lots may occur.

1. The applicant removes existing impervious surfaces at a ratio of one and one-half (1.5) square feet removed for every one (1) square foot added and restores these areas to a permeable surface…

…a. Permeable pavement systems are encouraged in the management of sites currently over the impervious surface limit and shall be credited as twenty-five (25) percent pervious for these sites when installed according to the requirements of

Section V.L.4.a.(2.)(d.)iii. Applicants are encouraged to replace existing impervious surfaces with natural vegetation at the 1.5 to 1 ratio listed above, however, permeable pavement systems may also be used. In these cases they are to replace existing impervious surfaces at a ratio of at least four (4) square feet converted for every one (1) square foot of new impervious surface being added;

2. The applicant removes existing impervious surfaces at a 1:1 ratio and restores those areas to a permeable surface and in addition, submits a comprehensive stormwater management plan that emphasized infiltration and onsite retention of stormwater for at least the two year 24-hour storm event through a combination of methods including buffer strips, swales, rainwater gardens, permeable pavement systems and other low impact development methods. The stormwater management plan must be designed by a registered engineer or landscape architect and installed as designed by a qualified professional.

a. Permeable pavement systems may be considered as 100% pervious when submitted as part of a stormwater management plan consistent with this section…

FT. WAYNE, IN

If construction techniques such as pervious pavement, block and concrete modular pavers, and grid pavers are used for off-street parking surfaces, each space provided as a result may serve in lieu of two (2) required off-street parking spaces, up to a maximum of 10% of the number of required spaces…

…Paving and drainage. All land which is placed in use for off-street parking and all driveways serving parking, delivery, and loading areas, shall be paved with asphalt, concrete, or other approved all-weather hard surface, including construction techniques such as pervious pavement; block, concrete, and similar modular pavers, and grid pavers; and shall be drained with materials and in a manner which meets the current minimum standards and specifications for parking areas adopted by the Board.

-Brian Phelps