City officials outline implementation of infill ordinance and 'site plan light' rules to reduce drainage costs

City Development Services and Watershed Protection staff told the Housing and Planning Committee on July 12 that the city is implementing the infill development ordinance intended to simplify review and reduce drainage-related costs for small lot subdivisions and certain small multifamily projects.

Brent Lloyd, a development officer in the Development Services Department, said the ordinance focuses on drainage requirements and administrative processes that historically were calibrated for large greenfield subdivisions. He described three primary project categories: very small lot re-subdivisions (parcels less than 17,780 square feet), projects up to 1 acre that require limited grading, and small-scale multifamily "site plan light" projects of roughly five to 16 units. "The ordinance will take effect next week on June 16," Lloyd said in the briefing materials and presentation.

Matt Holland of Watershed Protection explained that for parcels under 17,780 square feet the city will generally not require additional drainage review beyond what a single-family building permit requires. For parcels between 17,780 square feet and 1 acre staff described a simplified grading review and guardrails to limit lot-to-lot impacts. For site-plan-light multifamily projects (roughly half-acre or less) staff said they will allow simplified approaches; projects between a half-acre and 1 acre would be expected to connect to a nearby storm drain where feasible, with staff recommending connection up to about 50 feet rather than forcing very long, expensive runs of pipe.

Stakeholders asked for options to lower the cost and complexity of detention calculations. Staff said they plan to restore a simplified "modified rational method" option in the Drainage Criteria Manual for qualifying projects up to 1 acre and to explore modular detention (small, distributed detention devices on lots) and other options. Lloyd and Holland said the Technical Advisory Review Panel (TARP) and stakeholder working groups are reviewing proposed technical language; staff expected the storm-drain connection guidance to be posted for review in late June and to move toward adoption by late July or early September.

Staff cited cost impacts in past projects where drainage design and connections drove high up-front costs; one representative example discussed in the briefing material estimated drainage could account for roughly 40% of certain project development costs. Committee members asked about enforcement and lot-to-lot flooding. Liz Johnston, environmental officer with Watershed Protection, said the department maintains a private-pond inspection program and will inspect privately maintained ponds and take enforcement steps if a pond is not functioning or maintained properly; for other disputes staff said property owners may need to pursue legal remedies in some cases. The committee was advised that 311 may be used to request inspections and service tickets for suspected problems.

Staff said additional policy direction requested by council will be addressed in a July 1 report and through follow-up work with Austin Water, Austin Energy and Transportation/Public Works on utility and infrastructure triggers that can affect project feasibility. Lloyd and Holland said they expect the majority of qualifying projects to avoid the highest-cost drainage pathways and that the changes aim to make the city’s review process better matched to small infill and missing-middle housing.