P&Z to consider expanding impervious surface definitions

In advance of the city council instituting storm water fees, the Planning & Zoning Commission will consider Tuesday zoning ordinance amendments that will expand what is considered an impervious surface subject to stormwater runoff. Basically, the changes would align Kyle with more accepted impervious surface definitions in place in other communities with active stormwater management programs.

The meeting is scheduled to start at 6:30 p.m. Tuesday in the city hall council chambers. A public hearing is scheduled as part of the impervious surface agenda item.

These changes won’t have an immediate dramatic financial impact on homeowners because the city is considering a monthly stormwater fee that will be uniform for all. That’s because Kyle’s housing stock is relatively uniform. But, as the city grows and its housing stock becomes more diverse in size, it is expected residential stormwater fees will be calculated in proportion to the amount of impervious surface contained on a homeowner’s property. That means a homeowner with a large concrete deck, a swimming pool or a large paved entryway could pay more than a neighbor without any of these amenities.

The city is considering requiring commercial property owners, however, to pay a monthly stormwater utility fee based on the total area of impervious surface on their property.

The definitions will have an immediate effect on future developments because it will adjust the percentage of a property that can be covered by an impervious surface is each zoning district. Because more features of a property will be considered impervious, the percentages are increased under the terms of the proposed changes. For example, in residential areas zoned R-1-2, the total amount of a lot that can be covered in impervious surface will increase from 45 to 60 percent; in a warehouse zoned area, from 60 to 75 percent.

Under current definitions, only the actual home counts toward the amount of impervious surface on a residential property. "This manifests itself as a problem," according to the staff analysis that accompanies the proposed changes, "because stormwater detention facilities are effectively sized for expected impervious surfaces, but in Kyle usual and customary paved surfaces like driveways, sidewalks, patios, pool decks, etc., can’t be adequately calculated to be contained during a storm event."

In other words, if the newly created stormwater utility is going to be successful, it must be able to account for all impervious surfaces so "that more effective stormwater control can be implemented in the developmental process," the staff analysis said.

Under the new definition, "Impervious cover means roads, parking areas, buildings, rooftop landscapes, patios, decking and other construction limiting the absorption of water by covering the natural land surface; this shall include, but not be limited to, all streets and pavement within the development, and all other surfaces comprised of wood, stone, concrete, asphalt, metal, brick and other masonry, decorative water features like ponds and pools, and swimming pools. Improved areas established on a suitably engineered sub-base, whose purpose is to capture stormwater from the two-year storm event and recharge ground water, are not impervious."

The amendments will define a "a paved area" as one "surfaced with asphalt, concrete or similar durable pavement, providing a permanent, erosion-resistant, all-weather surface. Gravel, river rock, and/or stone dust (road base) are not acceptable paved surfaces. Proprietary, engineered pre-cast systems incorporating natural surfaces which allow for stormwater management as well as load-bearing vehicle storage such as Geoblocks, Grasscrete, and Truckpave, etc., also qualify as pavement."

P&Z commissioners will also be asked to consider conditional use permits that will enable the construction of a one-story, 16,686-square-foot facility on Seton Parkway, across the street from the under-construction Goodwill store, to be used as a BioLife Plasma Services facility; and one-story 9,000-square-foot "multi-tenant retail center" (mini strip-mall?) on the northbound I-35 frontage road, just north of the AMM Collision Center, between Windy Hill Road and the 149 highway.

The commissioners will also consider much-debated changes to that part of the zoning ordinance dealing with landscape requirements and possibly whether to remove the landscape provisions from Chapter 53 of the ordinance and making it a separate chapter. A public hearing is also attached to the landscape changes agenda item.

In fact, you can read the entire Planning & Zoning Commission agenda right here.