Pipe Bursting in San Marcos

San Marcos was a farm town with a few thousand residents into the 1960s, and most of what stands today was built after 1980. The Richmar and Barham neighborhoods near the old downtown and Mission Road hold the 1950s through 1970s housing stock. Lake San Marcos and the Discovery Hills area grew through the 1980s and 1990s, and San Elijo Hills, Twin Oaks Valley, and the newer Cal State San Marcos district filled in from the late 1990s through the 2010s.

That timeline means the sewer problems here differ from the older coastal cities. Instead of century-old clay riddled with roots, the typical San Marcos lateral is ABS plastic that was installed with a flaw: a belly, a crushed section, a separated joint. Trenchless methods suit those defects well because they can target a single spot without opening a trench through a finished yard. San Marcos sits within the countywide trenchless sewer services; the details below are specific to this city.

Housing eras, soils, and pipe

The Richmar and Barham tracts and the scattered older homes along Mission Road and Rancho Santa Fe Road were plumbed with vitrified clay laterals, often with cast iron under the slab or through the foundation. These neighborhoods also sit on the valley floor, where expansive clay soils swell in wet winters and shrink through dry summers. That seasonal movement opens clay joints a little more each year, and mature pepper trees, eucalyptus, and ficus do the rest. A home from the late 1940s into the 1960s may have Orangeburg fiber pipe, which flattens with age.

The 1980s and 1990s developments around Discovery Hills and Lake San Marcos moved to ABS. ABS is excellent material, but these were mass-graded hillside projects with deep engineered fill, and fill settles. A lateral that was laid at a good grade in 1988 can have a low spot today where the fill compacted beneath it. Shallow runs under driveways and the pipe stub near the street are the usual crush points.

San Elijo Hills and the other late-1990s to 2010s communities are the youngest in the county. Their laterals are ABS or PVC on steep cut-and-fill lots with long runs to a main in the street below. Problems there are almost always installation-related and localized, which is good news: the fix is usually short.

Matching method to defect

Every evaluation begins with hydro jetting and a camera run with a locator, recorded with footage marks.

• Sectional point repair is the first tool on a newer home. A short liner is cured precisely over a belly, a crack, or a separated joint, leaving the rest of the sound ABS untouched.
• CIPP lining is for the older clay laterals in Richmar and Barham with leaking joints along their full length, and for ABS runs with several scattered defects. The resin liner cures into one continuous pipe designed for decades of service. The the CIPP installer reference site covers resin types and cure methods.
• Pipe bursting replaces collapsed clay, flattened Orangeburg, or a badly bellied plastic run where a liner would only follow the sag. New HDPE is pulled through the path of the old pipe between two small pits.
• Spin-cast lining restores larger cast iron and concrete drains under commercial buildings in the Restaurant Row corridor and the industrial parks off Grand Avenue.

A liner cannot correct grade, so where the camera shows a deep belly, bursting or a dig at that one spot is the honest recommendation. The what happens on lining day and after describes how a crew moves from inspection to cleaning to lining to final camera in a single day for most laterals.

Permits, Vallecitos, and inspection

San Marcos is an incorporated city. The city issues the plumbing permit and any encroachment permit for work in the sidewalk or street, while Vallecitos Water District owns the sewer mains for almost the whole city and sets the standards for the connection and the cleanout. Expect the district or the city inspector to view the finished liner or new pipe on camera before any pit is backfilled. Unincorporated areas on the city's edges are permitted through County of San Diego Planning and Development Services.

DigAlert, the regional 811 service, must be called before any excavation, including the small pits a bursting job needs. In most San Diego County agencies the property owner maintains the lateral all the way to the main, which includes the stretch under the sidewalk and street. San Marcos has no point-of-sale sewer inspection requirement, but buyers of 1980s and 1990s homes increasingly request a camera report, and a documented repair makes that conversation short.

What an estimate visit involves

A licensed trenchless contractor will locate the cleanout, jet the line, and record a camera inspection while a locator marks the pipe route across the yard. The written estimate should list the method, the access points, the permits and which agency issues each, and the restoration included. On a hillside lot, ask how the crew will stage equipment without damaging slopes or drainage. Keep the video as your baseline record.

Pipe Bursting in San Marcos

How pipe bursting works

A steel cable is threaded through the old sewer line from a pit at one end to a pit at the other. A cone-shaped bursting head, with new high-density polyethylene pipe fused to it, is pulled through by a hydraulic unit. The head splits the old clay or cast iron outward into the soil and the new pipe follows in the same alignment at the same depth. The result is a single fused length of pipe with no joints for roots to find.

When bursting is the right call

• Collapsed sections — a liner needs a host pipe to hold its shape; a collapsed run has none.
• Bellies — a low spot that holds water stays a low spot after lining. Bursting lays new pipe on a fresh bed.
• Undersized lines — bursting can upsize a 3-inch lateral to 4 inches; lining slightly reduces diameter.
• Badly deformed pipe — Orangeburg that has flattened, or cast iron with most of its bottom gone.

What the job looks like

One pit at the house or cleanout, one at the property line or the street connection, each a few feet square. Utilities that cross within a foot or two of the sewer path are located and potholed first. The pull takes an hour or two; the whole job, including fusing, connections, inspection and backfill, is usually one day.

Permits and the street

If the downstream pit is in the sidewalk, parkway or street, a right-of-way permit and restoration to city standards are required in addition to the plumbing permit. If the connection at the main is replaced, the city inspects it before the pit closes. Confirm who is handling this before work starts.

More trenchless services in San Marcos

Questions we hear in San Marcos