Oak Knoll C

Oak Knoll: Providing Drainage Relief in a Dense Residential Area

Project Background

Austin residents near Oak Knoll Drive and Woodcrest Drive have experienced devastating structural flooding after rainstorms in recent years. The City of Austin embarked on a project to upgrade the existing infrastructure to increase capacity, for the purpose of mitigating future flooding risks and bringing the drainage system up to the city’s capacity standards. The project’s engineering firm, LAN, brought in HVJ during the design and permitting phase to provide a geotechnical investigation, including field exploration and testing, utility installation recommendations, alternative field exploration, design alternatives, and geophysical monitoring.

The physical constraints of the dense neighborhood and proximity to homeowners’ yards required that we complete our work using minimally invasive equipment, avoiding disruptions to residents, and regularly communicating with the homeowners throughout the process. HVJ’s commitment to thoughtful, reliable solution-development ensured a successful outcome while maintaining positive relationships with area homeowners.

Practice: Geotechnical Engineering

Sector: Flood Control

Location: Austin, Texas

Services: Utility Installation Recommendations


Oak Knoll

The Problem

Geotechnical investigation and construction needed to occur in a dense neighborhood and near residences. A large box culvert, to provide flooding relief, needed to be installed between multiple residences tied into an existing drainage system. However, conventional drilling rigs and equipment could not be used due to overhead power lines, trees, fences, and overall limited space.

Early on before beginning the project, we needed to provide detailed field and testing information to the property owners to obtain right of entry approval from the Condominium Association before beginning the project.

Our team was sensitive to the fact that our investigation and ultimate recommendations would impact area homeowners, as construction would be required in some of their yards. In one especially complex construction challenge, the box culvert needed to be installed within five feet of a residence. 

The Goal

Our client needed reliable geotechnical recommendations to successfully upgrade the new storm lines and install the box culvert to provide the necessary increased drainage capacity. The pressing need to eliminate flooding in the neighborhood required a thorough evaluation and review of all potential options.

Our goal was to provide the client and design team with reliable recommendations to upgrade the storm lines, install the box culvert successfully, and minimize disruptions to area homeowners throughout the process.

The Solution and Results

To overcome our inability to use a standard drilling rig, we used a mini skid steer on tracks with a small bucket to excavate and retrieve samples. Our experience in the Austin area told us that the bedrock would be shallow, so we used the bucket to obtain soil samples and determine the bedrock depth at multiple locations. By combining the resulting information with a geotechnical analysis conducted at an earlier phase of this project, we were able to provide reliable results and recommendations to our client and team members for carrying out the design of the new drainage system.

We recommended a soldier pile and lagging system to shore up the excavation where the box culvert was very close to the residence. Since limestone drilling and excavation would occur very close to some of the residences, we recommended Round Rock Geophysical Consultants for Structural Vibration Monitoring & Control during the project’s construction phase.

Our client incorporated our recommendations into the drainage system’s design and included a structural vibration monitoring system, with construction beginning this year. When completed, the resulting drainage system will consist of a 7x3-foot reinforced concrete box storm sewer to create much-needed flooding relief for the neighborhood. Our innovative exploration technique allowed us to obtain necessary samples with minimally invasive equipment in a very confined sensitive area.

Our team’s clear and consistent communication with homeowners and the client was vital to this project’s success. The HVJ team was sensitive to residents’ needs, frequently educating them as field activities were occurring and staying in regular communication with all homeowners. Excellent communication is a core value at HVJ, as we are committed to the project’s technical success and peace of mind for those it affects. Our team’s people skills were integral in helping all field activities run smoothly and maintaining positive relationships with homeowners and the Condominium Association.

"HVJ has a very professional team that is responsive and clearly communicates project challenges and potential solutions. HVJ is open to being part of a larger team, providing feedback and guidance on important project decisions."

Laura Casset, Regional Stormwater Manager at Lockwood, Andrews & Newnam, Inc.

Share this story