Storm Drain Lining

What fails in storm drains

Storm systems were built to a lower standard than sanitary sewers, because what they carry is only rain, and they were built from materials that do not last. Corrugated metal pipe, galvanized or aluminized steel, is the workhorse of parking lots, subdivisions and road culverts from the 1950s on, and it rusts through along the bottom where the water runs, until the invert is gone and the soil above it washes in. Reinforced concrete pipe lasts longer but opens at the joints as the ground settles, and in acidic soils its crown spalls. Clay and concrete roof drains under slabs crack and separate. Plastic storm pipe deforms under traffic where it was laid shallow. The symptoms are the same everywhere: a sinkhole in the lot, a dip in the road over a culvert, a catch basin that drains slowly or not at all, water surfacing where it should not, and a storm system that floods the property it was built to protect.

Lining storm pipe

Storm pipe is lined by the same methods as sanitary pipe, chosen by diameter and condition. Cured-in-place pipe handles everything from a four-inch roof drain to a four-foot culvert: the liner is inverted or pulled in from a catch basin, a manhole or a culvert end, cured with steam, hot water or ultraviolet light, and becomes a structural pipe inside the old one, so a corrugated metal pipe with no invert left is still a lining job as long as its shape is intact. UV-cured fiberglass liners are a particular fit for storm work, because they are strong at a thin wall, cure fast and are less sensitive to groundwater than resins cured with water. Spin-cast lining takes over on large culverts, arches and box structures, where a sprayed mortar or geopolymer shell costs less per foot than any tube. A point repair handles a single failed joint in a concrete main. And where the pipe has collapsed, lost its grade or been crushed by traffic, the honest answer is a burst or an open cut through that section.

Roof drains and under-slab drainage

A commercial building's roof drains run down inside the walls and under the slab to the storm system, and when one cracks the water goes under the floor. These are lined like any small-diameter line: from the roof drain or a cleanout, with a small CIPP liner or, in very small diameters, an epoxy coating, without opening the floor. The same applies to parking-garage drainage, loading-dock drains and the trench drains in an industrial floor.

Flow and weather

The thing that makes storm lining different from sanitary lining is that nobody controls when the water comes. A storm liner has to cure in a dry pipe, so the work is scheduled around the forecast, the upstream catch basins are plugged or diverted, and on a culvert the stream is bypassed or the work is done in the dry season. A contractor who does storm work plans for the rain that arrives anyway. On a municipal storm main or a culvert under a highway, the bypass and the traffic plan are a larger part of the job than the liner itself.

Where storm lining is used most

• Corrugated metal pipe under shopping-center and apartment parking lots, rusted through at the invert and sinking the pavement
• Road culverts under county and state highways, where lining avoids a closure and a detour
• Concrete storm mains with open joints in subdivisions built on settling ground
• Roof drains and under-slab storm lines in commercial, institutional and industrial buildings
• Catch basin leads and laterals, lined from the basin without opening the lot
• Detention and outfall structures, lined to stop the erosion and undermining that follows a leak

Permits and the agencies involved

Private storm drainage on a commercial property takes a building or plumbing permit from the local jurisdiction, and where the system discharges to a municipal storm sewer or a waterway, the stormwater authority may want to see the work. A culvert under a public road belongs to the road agency, which permits and often procures the work itself. Any pit in the right-of-way takes a street-opening permit; any excavation anywhere takes a utility-locate call. Lining from the catch basins avoids nearly all of it.

What drives the price

Storm lining is priced per foot by diameter, with cleaning, flow management, access and traffic control itemized. Against replacement of a storm main under a parking lot, which means closing the lot, sawcutting and trenching the pavement, and repaving, lining routinely costs a third to a half and finishes in a day or two. Against replacement of a culvert under a road, the comparison is not close. The work is scoped from a camera survey, never from a phone call.

Finding a contractor

Several of the installers listed on this site do storm and municipal lining, and their state pages say so. For a parking lot, a culvert or a storm main outside a covered state, the national line locates a qualified storm-lining contractor and makes the introduction at no charge.

Estimates are free. Call now. (855) 804-1434