Case Study: Sand Filter Compliance in Austin, TX
A commonly used stormwater quality device utilized in the Austin area is a Sand filter. These Sand filters are specified on all types of facilities and consist of basins that capture and filter stormwater runoff through a bed of sand in the floor of the system. They are employed to help remove pollutants from stormwater runoff before it enters surface or underground water conveyances. In order for a sand filter to work properly, it is imperative that they be consistently maintained.
The Parking Spot received a notice of violation from the City of Austin regarding their Sand Filters being out of compliance. The issues were excessive sediment and vegetation in the splitter boxes, excessive vegetation and trees in the filter and detention basins, gaps in the expansion joints, blown out rip rap at the outfall, as well as some minor holes along the filter walls and grading issues. The sum of these circumstances reduced the Sand Filters’ ability to infiltrate and filter runoff effectively which prevents it from meeting the pollution reduction goals of The City of Austin’s Watershed Protection Ordinances thus making it out of compliance.
The Parking Spot ownership, wanting to be in compliance and facing the prospect of fines of $2,000 per day per violation, commissioned Construction EcoServices to communicate on their behalf with the City of Austin officials to implement a solution and correcting the issues in the Sand Filter.
We removed sediment and vegetation in the splitter boxes, excessive vegetation and trees in the filter and detention basins, filled the gaps in the expansion joints with Sikaflex Expansion Joint Filler, and repaired the blown out rip rap at the outfall, as well as filling and packing the minor holes, and correcting the grading issues.
Additionally we educated the owner for the benefit of their landscaper in regards to their current maintenance scope and frequencies to mitigate these issues in the future. The changes included: mowing not only the detention basin once a month, but also cutting and removing all vegetation in the splitter boxes and Sand Filters once a month, bi-annual litter removal, performing a visual inspection once a month to ensure the maintenance measures are proving to be effective and having a professional review the Sand Filter once a year to ensure everything in the system is functioning properly. This new maintenance approach will greatly reduce the opportunity for these issues to occur in the future.
By staying in constant communication with The Parking Spot and the City of Austin during the repair process, we were able to create an efficient line of communication between all parties involved. Once the work was completed and approved by the owner, we were able to bring all parties together and quickly obtain a ‘Letter of Release’ from the city indicating that the Sand Filter is now in compliance.
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