City of Austin Guest Post: Success of the Award-Winning Stormwater Pond Safety Program
Freese and Nichols, Inc. would like to thank Eduardo Acosta, P.E., CFM, LEED AP (pictured in the middle below), the former City of Austin Stormwater Pond Safety Program Manager, for the following guest post.
The City of Austin’s Stormwater Pond Safety Program (SPSP) is recognized as one of the nation’s premier municipal dam safety programs and received the 2013 South Region Award of Merit by the Association of State Dam Safety Officials. The SPSP’s success is due in large part to the professional engineering services provided by Freese and Nichols. The program was created in 2002 to ensure that City-owned ponds meet the State of Texas requirements for dam safety. The City of Austin (the City) owns, maintains, and operates more than 800 water quality and detention ponds built as a result of residential and commercial developments. Currently the SPSP has an inventory of more than 250 dams, 114 of which are classified as high-hazard dams, as well as three floodwalls. SPSP utilizes a combination of regulations, inspections, collaboration, emergency preparedness, dam modernization and ongoing inventory management to ensure dam safety throughout Austin.
Regulation and Inspection
The City’s Drainage Criteria Manual (DCM) requires certification of all dams and includes specific certification language and probable maximum flood (PMF) design storm data in an effort to provide standardization of the design and analysis of dams subjected to Austin development code. The DCM defines dams as ponds with an embankment of six feet or greater. With the advent of the SPSP, an inspection protocol was created specifically for dams. Engineering inspection reports for dams are generated to identify maintenance needs. The program also regularly reviews the hazard classification of its low-hazard dams by monitoring new development and annexed areas to determine if downstream impacts have changed.
Emergency Preparedness and Collaboration
SPSP collaborates with the City’s Flood Early Warning System (FEWS) staff in utilizing predictive rainfall amounts. Precipitation thresholds for monitored dams are tracked by FEWS and SPSP staff. When precipitation depths have reached the alarm thresholds, dam safety personnel are notified via audible pager alerts that there is a high potential for water surface elevations to rise to a pre-determined level. This provides advance warning for SPSP staff should an Emergency Action Plan (EAP) go into effect. Since the creation of the SPSP, staff has created EAPs for 28 state-regulated dams in Austin and continues to develop four EAPs each year for its high-hazard dams.
Dam modernization is one of the main activities undertaken by the SPSP. High-hazard dams are ranked based on downstream risks and are used to develop a 10-year Capital Improvement Projects plan. Seven modernization projects have been completed to date, with the upgraded dams able to safely pass 75 percent of the PMF. The City contracts with Freese and Nichols for assistance during the design and construction phases. Currently three dams are under design.
Ongoing Inventory Management
In 2007, the City hired Freese and Nichols to evaluate and prioritize the City’s dam inventory. Since the 2007 report, the City has re-evaluated its inventory by reviewing all site plans. This investigation, along with the inclusion of newly annexed dams, resulted in a near doubling of the SPSP’s dam inventory. The City chose to reprioritize its growing inventory by utilizing the TCEQ-outlined Simplified Breach Analysis (SBA), as well as internal scripting that partially automated the SBA process to focus modernization efforts on the largest areas of risk. This ongoing process has also allowed the City to reduce dam inventory by recognizing the facilities that do not pose a risk to the public and are considered low hazard.
In conclusion, the SPSP has unquestionably improved the City’s dam safety program through the use of regulations, a consistent inspection plan, department and state agency collaboration, emergency preparedness, a modernization program, and the ongoing inventory management to ensure the safety of the citizens of Austin. Freese and Nichols has been involved in each of these efforts and I would like to thank them for their hard work, integrity and utmost professionalism. After seven years as the City of Austin’s Stormwater Pond Safety Program Manager, I have accepted a position with Austin Energy but am proud of the work we have accomplished together during my tenure.