Many USPS® sites have stormwater retention or detention basins to manage stormwater runoff to prevent flooding, erosion, and discharge of pollutants to surface waters. Sites with retention or detention basins require specific management practices and may be regulated under federal and state/local laws.
Stormwater basins are man-made depressions that collect stormwater runoff and control discharges. These basins generally fall into two categories:
n Retention basins (also known as wet basins or wet ponds) are designed to retain water for extended time periods. They typically have a permanent pool of water throughout the year (or at least during the wet season) and often look like man-made ponds.
n Detention basins (also known as dry basins or dry ponds) are designed to detain or temporarily store water after a storm. Unlike retention basins, detention basins are designed to empty completely and do not have a large permanent pool of water.
Routine preventative maintenance, landscaping, and inspections, as well as prompt corrective actions for any issues identified, keep the basins functioning properly and maintain water quality. Sites with basins must:
n Identify the location of all retention and detention basins on the property, including risers and outfalls.
n Conduct and document routine visual inspections of each retention and detention basin using the inspection checklist found at blue.usps.gov/sustainability/environmental/_docs/forms/form-sw-ret-det-inspectionchecklist.docx.
n Perform landscaping and grounds maintenance necessary to ensure basin functionality.
n Adhere to Postal Service™ Zero Discharge policy, including general good housekeeping and chemical storage requirements.
n Conduct preventative maintenance and complete any other routine repairs and corrective actions necessary to ensure proper basin functionality and stormwater drainage, including cleaning and removing debris and trash, accumulated sediments, and excess vegetation.
Contact the Facilities department at (855) 444-6375 for certain corrective actions involving structural repairs, alterations, upgrades, and other non-routine repairs.
Sites with basins must never:
n Operate vehicles on embankments or in basins, except for light-duty lawn equipment necessary to maintain grounds.
n Put landscape waste (e.g., grass clippings and branches) or other materials in basins.
n Apply pesticides within the basin.
Note that stormwater basins may require permits or have specific design and operating standards in addition to what is discussed above. Review local regulations and issued permits and comply with all requirements.
For more information on the proper management of stormwater basins, please contact your designated USPS Environmental Specialist at blue.usps.gov/sustainability/regional-environmental-compliance-all.htm or refer to the Stormwater Retention and Detention Basins Environmental Compliance Bulletin at blue.usps.gov/sustainability/environmental/_pdf/bp-sw-ret-det.pdf.
— Environmental Affairs and Corporate Sustainability,
Corporate Affairs, 5-16-24
