Council approves Westlake Dermatology site plan after engineers explain two stormwater waivers

City engineering consultant Giancarlo presented the Westlake Dermatology site and NPS plan and explained the applicant’s two requested waivers related to stormwater peak-flow control and treatment-area routing.

Giancarlo told council the site’s impervious cover would increase from 47.45% to 49.36%, an increase of about 700 square feet, and that the hydrologic analysis shows the proposed conditions produce a higher discharge at the site’s point of analysis (from 19.35 to 27.00 cubic feet per second, an increase of 8.37 cfs). He said the design shifts the mitigation downstream and that at a point 300 feet downstream the plan shows a net reduction of 3.63 cfs.

Giancarlo described the applicant’s treatment train — a bioscape vault, vegetative filter strips and a wet-well pump — and said TxDOT has reviewed the hydraulic profile and found the ditch can contain the modeled flows. When Council asked about pump reliability and maintenance, Giancarlo said the developer will record maintenance obligations in covenants and declarations; he added that the city will inspect functionality (including pumps) at least once every five years. He told the council: "It is privately owned and maintained ... the city is not intended to pick up on the maintenance of the private development at any point."

Resident John Wickens, speaking in public comment on the item, asked whether the maintenance obligation covered the entire system (pond, vault, pipes, filter strips and spreaders); staff confirmed it does and that it is a perpetual private maintenance obligation recorded against the property. Councilmember discussion noted the single shared driveway (avoiding a second curb cut) and topographic constraints that shaped the waiver requests. A motion to approve the site and NPS plan with the two waivers carried unanimously.