Protecting Site Drains: Guards, Covers and Inlet Filters
Stopping sediment and pollutants entering the drain - drain guards, inlet filters and covers, where each is used, and how to keep the drainage system clear.
Site drains need protecting because surface water drains usually discharge to a watercourse, so sediment, silt or a spill entering a drain can cause pollution downstream. The controls are: drain guards and inlet filters, which sit in or over a gully to filter out sediment and, in some cases, absorb hydrocarbons while still letting water through; and drain covers or mats, which fully seal a drain to keep everything out during a spill risk or a specific operation. Guards and filters are for ongoing sediment protection; covers are for full, temporary sealing.
Why the drain is the weak point
A surface water drain is designed to take rainwater away usually to a watercourse. On a construction site, that same drain will happily carry away silt-laden runoff, a fuel spill or wash-out water straight to the river if nothing stops it. So the drain is where site pollution most easily escapes, and it's exactly what an environmental inspection checks. Protecting the drains is protecting the watercourse downstream.
Drain guards and inlet filters
Drain guards and inlet filters fit into or over a gully or drain inlet. They filter the water passing into the drain, capturing sediment and silt, and some types also absorb hydrocarbons (oil, fuel) to catch minor drips and leaks, while still allowing water to drain through so the gully doesn't flood. They're the everyday, ongoing protection for a drain that has to keep functioning letting clean water through while holding sediment and pollutants back. They need checking and cleaning as they fill.
Covers for full protection
- 1 Drain covers or sealing mats fully close off a drain, keeping everything out.
- 2 Used where there's a specific spill risk or an operation that could contaminate refuelling, concrete works nearby.
- 3 They provide temporary, total protection while that risk is present.
- 4 They must be removed appropriately afterwards so the drain functions again.
| Control | Best for |
|---|---|
| Drain guards / inlet filters | Ongoing sediment protection while the drain keeps functioning, some types also absorb minor hydrocarbon drips |
| Drain covers / sealing mats | Temporary, total sealing during a specific spill risk or operation, e.g. refuelling or nearby concrete works |
Frequently asked questions
-
How do you protect drains on a construction site?
With drain guards and inlet filters that sit in or over a gully to filter out sediment (and, in some types, absorb hydrocarbons) while letting water through, and with drain covers or mats that fully seal a drain during a specific spill risk. Guards are for ongoing sediment protection; covers for temporary total sealing. Both must be maintained. -
What is a drain guard?
A drain guard (or inlet filter) fits into or over a drain or gully and filters the water entering it, capturing sediment and silt, with some types also absorbing oil and fuel, while still letting water drain through. It provides ongoing protection for a drain that has to keep functioning on a working site. -
Why do site drains need protecting?
Because surface water drains usually discharge to a watercourse, so sediment, silt or a spill entering a drain can cause pollution downstream one of the most common ways site pollution escapes, and a key thing environmental inspections check. Protecting the drains protects the receiving watercourse.
Control it at source, with SSI Environmental
SSI Environmental has supplied spill, sediment and site environmental protection products across Ireland since 1996, from silt fences and dewatering bags to drain guards and plant nappies. Tell us about your site and its planning conditions, and we'll help you specify the controls to keep sediment and pollution where they belong. Call 01 8665676.