Subsurface Inspections
As the City of Austin continues to explode with new development so does their detention and stormwater requirements. Typically, most commercial stormwater control measures are inspected by the City of Austin every 3 years, however subsurface stormwater controls have more requirements for owners and developers. Subsurface Pond Maintenance Plan with the City of Austin requiring inspection reports for the water quality rainwater cistern (underground) and associated wet well and pump system. The cistern is required to be inspected by a Professional Engineer (PE) at least once every six months and at least once annually during, or immediately following, a significant rainfall event to evaluate facility operation. The plan also requires a drawdown report to be completed on the cistern at least once a year.
Maintenance Requirements
Remove sediment from the inlet structure and sedimentation chamber basin when sediment buildup reaches a depth of 6 inches or when the proper functioning of inlet and outlet structures is impaired. Sediment should be cleared from the inlet structure at least every year and from the sedimentation basin at least every 5 years.
Media Replacement
Maintenance of the filter media is necessary when the drawdown time exceeds 96 hours, provided all other components of the subsurface SCM pond are functioning correctly. When this occurs, the upper layer of sand should be removed and replaced with new material meeting the original specifications. If dewatering of the system is necessary due to lack of functionality, ensure dewatering is properly conducted.
- RDebris and Litter Removal. Debris and litter should be removed regularly. Particular attention should be paid to floating debris that can eventually clog the control device or riser.
- RFilter Underdrain. Clean the underdrain piping network to remove any sediment buildup as needed to maintain design drawdown time.
- RResponsibility. The responsibility of the inspection and maintenance of all subsurface SCMs ponds shall be the responsibility of the operator owner of the facilities.
From inspection findings, maintenance recommendations will need to be performed to correct any deficiencies that are found from the inspections. Once the deficiencies have been corrected and documented, an updated report should be submitted to the City of Austin for approval.
Please feel free to contact us directly with any questions regarding these regulations or services. We can be reached directly at (281) 723-1015, or by email at [email protected]