Maccaferri presenting at IECA 2016 case history about the employment of Terramesh System at Harold Court East Regional Service Center in Austin, TX.
Superior quality of work along with the choice of materials, assured a solid, pleasant looking, HITEC evaluated outcome
Maccaferri Inc. is very pleased to have had a project paper accepted for presentation at the International Erosion Control Association’s Annual Conference, this February in San Antonio, TX.
The topic of the project is the use of Terramesh on a Reinforced Soil Slope at the Harold Court East Regional Service Center in Austin, Texas.
Below are some highlights of the paper:
The Harold Court East Regional Service Center (HCERSC) is located on approximately 23.3 acres of a 74.9-acre tract. This property contributes to Fort Branch Creek and Boggy Creek where both are classified as urban watersheds.
The HCERSC is a City-owned multi-purpose facility shared by multiple departments including Public Works, Watershed Protection, Fleet Services and the Austin Water Utility and for storage uses.
Unstable slopes on the property have resulted in periodic movement of the embankment. Therefore, the City of Austin contracted engineering, geotechnical and environmental studies to respond to the conditions. The findings concluded that permanent slope stabilization was required, given that an existing 48-inch storm drain outfall at the bottom of the western slope had become displaced and damaged due to the shifting embankment and was in need of repair. This embankment had damaged an existing wastewater main, and erosion of the embankment along the southern perimeter had eliminated the original storm drain outfall.
The project was initially designed as a series of 9 ft. tall gravity retaining walls along the steep slope. The challenging in-situ conditions lead the designer to review and optimize the design into a series of 9 ft. mechanically stabilized earth (MSE) retaining walls separated by vegetative terraces.
The project improvements included slope controls constructed on the eroding embankment along the western and southern perimeters of the facility to prevent further migration of the material into Fort Branch Creek and to provide improved worker safety and function of the site for the material storage yard. The slope controls consist of multiple rows of Maccaferri Terramesh System walls separated by vegetative terraces with a service road to provide access to the proposed bio-filtration pond. The project improvements also included repairs and upgrades to the existing storm sewer system currently serving the facility and a water quality treatment system. Additional benefits to the existing facility included upgrades to the existing sidewalks, screening from adjacent landowners, and landscaping that would bring the site into compliance with current codes.
Several challenges arose during construction, such as additional excavation; borrow material and removal of waste. Indeed, the contractor encountered many unforeseen conditions including an unstable, saturated slope resulting in a series of slide failures, endangerment of a high voltage tower, an undocumented storm water system, underground, groundwater seeps exacerbating unstable slope conditions and deficiencies in quantity calculations.
The original contract allowed 330 working days for completion of this project, but the unforeseen challenges lead the project to be completed in 2015. The improvements at HCERSC are now close to completion and the attention to detail and construction by the installer has added invaluable precautionary measures when it comes to safety, environmental protection and structural stability.
With the superior quality of work along with the choice of materials, the outcome is solid, pleasant looking and is one of the few MSE wall systems that have been HITEC evaluated. The City of Austin is well known for its outstanding effort in green and environmentally friendly solutions, was able to have most of the in situ material reutilized. With the Terramesh System, the quantity of rock is limited in lieu of a larger quantity of structural backfill and the City of Austin’s authorization to allow the utilization of the fill material to consist of a mix of limestone rock and crushed concrete deriving from the demolition and excavations.