Summary of Water Quality Recommendations
(to contain silt erosion during highway construction)
* More upland controls designed to contain silt erosion at its source.
* Installation of detention ponds to capture silt prior to any grading of soil.
* Better phasing of construction to reduce exposure of erodable material.
* Better training of engineers and inspectors on reducing silt runoff.
(to filter oil and grease from highway runoff
after road is in use)
* Set measurable water quality standards for stormwater runoff.
* Identify and protect major aquifer recharge features from runoff.
* Set up a permanent maintenance program for water quality control devices, budgeted from the inception of highway planning, and overseen by a Water Quality Specialist.
* Minimize runoff volume from impervious cover by more use of infiltration devices to ensure slow ground percolation to maintain creek baseflows.
* Construction of water quality ponds on parts of Loop 360 and MoPac that
currently lack them.
Retrofitting Inadequate Water Quality Controls
* Find an alternative to the vertical sand filters used in ponds on MoPac and the Outer Loop that malfunction or perform poorly.
* Possible retrofit of the TxDOT Regional Water Quality Pond at Loop 360, because of its proximity to Barton Springs, if monitoring shows that it fails to protect Barton Creek.
* Groundwater tracing study to determine groundwater flow rates and velocity.
Monitoring and Studies
* Study to determine baseline water quality in the Edwards Aquifer, to be continuously monitored as urbanization increases.
* Permanent monitoring of effectiveness of water quality devices, to be included in the budgets of highway projects from their inception.
* TxDOT should maintain records of water quality pond maintenance and inspection.
* TxDOT should collect turbidity measurements during rain events to assess effectiveness of sediment and erosion control. -- N.E.