Aransas Pass Pump Station 3 Emergency Repairs
Seawall Embankment Repairs and Stormwater Pump Station Evaluation
The City of Aransas Pass is protected from storm surges and coastal flooding by an earthen seawall that surrounds major parts of the city and is drained by three stormwater pump station facilities. During a significant storm event that occurred in the Summer of 2020, a portion of the seawall embankment failed, resulting in the collapse of the discharge pipes at Pump Station No. 3 and putting the facility out of service. This pump station is responsible for draining the most populous areas of the city and is regarded as a critical facility.
The objectives of this project are:
- To provide guidance to the City for the repairs required to stabilize the failed area of the seawall.
- To return Pump Station No. 3 to a safe operating condition.
- To improve the operational capacity of the system to better drain the interior parts of the City.
KFA has completed the evaluation and design of emergency repairs to the earthen embankment seawall which will include the replacement of the failed segments of the stormwater discharge lines. In addition, KFA is assisting with the assessment of the pump station and providing recommendations to retrofit the wet well intake structure with a new trash rack, replacement/repair of the pumps, and other related improvements to maximize pumping capacity. Reconstruction of the embankment and repairs to the pump station facilities are anticipated to begin by the end of 2020.
Unique aspects of this project include:
- KFA staff mobilized within less than 48 hours to the site to observe the failure and aid with providing recommendations for the immediate stabilization of the berm and operation of the pump station facilities.
- Due to the sloughed embankment, steep slope and sandy soil conditions, access to the area of failure is limited. KFA’s approach for repairs consists of laying back the slope in benched sections to stabilize the area during construction and reconstruct in lifts.
- The presence of a shallow groundwater table presents challenges for the repair of the embankment. To reduce construction costs associated with the control of water, our approach is to construct repairs during low tide when there is greater access to the area. The toe of slope will be stabilized using “bull-rock” worked into the subgrade to create a level surface for placement of the embankment fill.
KFA is currently working with the City to help implement the recommended repairs and pump station improvements. Construction is anticipated to begin by the end of 2020. Once completed, the project will help protect urban areas of the city by helping to reduce the frequency of flooding and improving protection against coastal storm surge flooding.