§ 20-921. Pervious pavement.

Properly designed, installed, and maintained pervious pavements have the capacity to allow for stormwater detention and/or infiltration. When not properly designed, installed, and maintained pervious pavements fail to facilitate the detention and/or infiltration of stormwater. Additionally, pervious pavements contribute to the creation of heat islands and do not provide the same surface water management benefits as native vegetative cover. For these reasons, it is necessary to regulate the lot coverage, design, installation, and maintenance of these systems.

(1)

Lot coverage: Pervious pavements are considered to constitute lot coverage; however, when built to the standards espoused in this section they do not constitute impervious surfaces. Systems not built to the standards espoused in this section are considered to constitute impervious surfaces.

(2)

Location restrictions:

a.

Pervious pavements may not be installed in areas where trash or garbage receptacles will be stored.

(3)

Design and installation:

a.

A building permit is required for the instillation of pervious pavement systems.

b.

Pervious pavement systems must be designed to provide for rate and volume control for the first half-inch of treatment area and follow the current version of the City of Chanhassen Standard Specification and Detail Plates. Treatment area includes the total square footage of the pervious pavement system plus the total square footage of impervious surface draining directly to the pervious pavement system.

c.

To meet the city's definition of pervious pavement the system must: 1) be designed in compliance with standards established by the Interlocking Concrete Pavement Institute (ICPI); 2) be installed by an ICPI certified installer; and 3) be designed to meet or exceed the standards listed in paragraph (3)b.

d.

The city engineer may permit pervious pavement technologies other than permeable interlocking concrete pavers, so long as the city engineer determines: 1) they are functionally equivalent or better; 2) the system is designed in compliance with accepted guidelines and is installed by an appropriately certified installer; and 3) the system will meet or exceed the standards listed in paragraph (3)b.

(4)

Maintenance:

a.

The owner of a pervious paver system must enter into a maintenance agreement with the city to ensure the system performs as designed in perpetuity. This agreement must conform to the manufactures guidelines, and stipulate the frequency and type of maintenance to be performed.

(5)

District restrictions:

a.

Planned Unit Developments Residential Districts (PUDR) are limited to the lot coverage specified by their ordinance and/or compliance table. For PUDRs created before June 11, 2018, the terms hardcover, hard surface, impervious surface, and similar phrases, shall be understood to mean lot cover inclusive of both pervious pavements and impervious surfaces, and in no circumstance shall the failure of the ordinance or compliance table to mention pervious pavements be understood to mean that pervious pavements are not subject to the lot cover, hardcover, hardscape, or similarly identified limits that govern the PUDR.

b.

Shoreland Management District restricts properties zoned Single-Family Residential District (RSF) to 25 percent lot coverage.

(Ord. No. 633, § 4, 6-25-18)