SAWS Sewer Rehabilitation in San Antonio: What Contractors Need to Know About CIPP, Pipe Bursting, and Engineering Submittals

If you're a contractor working on sewer rehabilitation projects in San Antonio, you've probably noticed there's a lot of this work going around. That's not a coincidence. SAWS is in the middle of a massive infrastructure investment driven by a federal consent decree, and the work isn't slowing down anytime soon.

This post covers why all this sewer rehab work is happening, the two most common trenchless methods being used, and what engineering submittals contractors typically need to have in place before work begins.

Why SAWS Is Rehabbing So Much Sewer Infrastructure

In 2013, SAWS entered into a consent decree with the U.S. Environmental Protection Agency and the Texas Commission on Environmental Quality to address Clean Water Act violations. Between 2006 and 2012, SAWS had roughly 2,200 sanitary sewer overflows that discharged an estimated 23 million gallons of raw sewage into local waterways. The consent decree required SAWS to invest an estimated $1.2 billion in its sewer system over a 10 to 12 year period to reduce sewer spills and rehabilitate aging infrastructure.

That work includes system-wide inspection and cleaning of the approximately 5,200 miles of gravity sewer in the SAWS collection system, along with the targeted replacement and rehabilitation of pipes identified as structurally deficient. SAWS has been steadily working through this program, and the capital investment in wastewater infrastructure continues to be one of the largest line items in their annual CIP budget.

For contractors, this means a sustained pipeline of sewer rehabilitation projects across San Antonio for the foreseeable future. The work ranges from small-diameter gravity main lining to large-diameter trunk line rehabilitation, and it touches neighborhoods across the entire service area.

The Two Main Trenchless Methods

Most of the SAWS sewer rehabilitation work uses trenchless methods, which allow contractors to repair or replace existing pipes without digging up the entire line. The two most common methods you'll see on these projects are CIPP lining and pipe bursting.

CIPP (Cured-In-Place Pipe)

CIPP is a rehabilitation method where a flexible liner saturated with resin is inserted into the existing pipe, inflated to press against the pipe walls, and then cured using heat (hot water, steam) or UV light. Once the resin hardens, you have a new structural pipe formed inside the old one. The result is a smooth, jointless, corrosion-resistant lining that eliminates infiltration and extends the life of the pipe by 50 years or more.

CIPP is well suited for pipes that are cracked, have joint failures, or are experiencing infiltration, but still have their general shape and alignment intact. It works across a wide range of diameters and is one of the most widely used trenchless rehab methods in the country. The process is relatively fast on a per-segment basis, typically taking a couple of days per manhole-to-manhole run depending on pipe size and curing method.

One thing to keep in mind with CIPP is that the liner slightly reduces the internal diameter of the pipe. For most applications this isn't an issue, but on lines where capacity is already tight, the hydraulic impact needs to be evaluated.

The existing sewer flow has to be bypassed during installation. The pipe needs to be cleaned, inspected with CCTV, and prepped before the liner goes in. After curing, lateral connections are reopened using robotic cutters from inside the pipe, and a final CCTV inspection confirms the installation.

Pipe Bursting

Pipe bursting is a replacement method rather than a rehabilitation method. A bursting head is pulled through the existing pipe, fracturing it outward into the surrounding soil while simultaneously pulling a new pipe (typically HDPE) into place behind it. The old pipe is destroyed and replaced in a single operation.

Pipe bursting is the better option when the existing pipe is too far gone for lining. If the pipe has collapsed, is severely deteriorated, or is made of a material that won't support a CIPP liner, pipe bursting gives you a completely new pipe in the same alignment. It also allows you to upsize the pipe if needed, which CIPP cannot do.

The trade-off is that pipe bursting requires access pits at each end of the run, and every lateral connection along the segment needs to be excavated and reconnected to the new main. It's more disruptive than CIPP but still far less invasive than full open-trench replacement.

Like CIPP, pipe bursting requires bypass pumping during the work. The existing flow has to be diverted around the segment being replaced.

Engineering Submittals Contractors Need

This is where a lot of contractors run into questions. Depending on the project specifications and the reviewing agency's requirements, you may need several engineering deliverables before you can start work.

Bypass Pumping Plan

Most SAWS sewer rehab projects require a sealed bypass pumping plan prepared by a licensed Professional Engineer. The plan demonstrates that the temporary pumping system can handle the peak wastewater flows during construction without causing a spill. It includes flow analysis, pump sizing, piping layout, plug placement, and contingency provisions. I wrote a full post on this topic recently if you want more detail on what goes into a bypass plan.

On larger projects with multiple segments, the bypass plan may need to address each setup individually, especially on leapfrog-style projects where the bypass system moves progressively as each section is completed.

Structural Calculations and Design Submittals

For CIPP projects, the contractor typically submits the liner design, which includes the resin type, liner thickness, and structural calculations demonstrating that the cured liner meets the required design life and loading conditions. Depending on the spec, these calculations may need to be sealed by a PE.

For pipe bursting projects, the engineering submittals typically address the new pipe material and specifications, the bursting head size relative to the existing and new pipe diameters, and any structural considerations for the pipe under the expected loading conditions. If the project involves restrained joints or thrust restraint at connections, those calculations need to be included.

TCEQ and Stormwater Compliance

If the project disturbs more than one acre of land (which is less common on trenchless work but does happen on larger projects with multiple excavation points), a Notice of Intent needs to be filed with TCEQ under the Construction General Permit. The contractor is responsible for having a Stormwater Pollution Prevention Plan (SWPPP) in place.

Even on smaller projects, SAWS and the City may require erosion and sediment controls at access pits and staging areas. The project specifications will spell out what's required.

Pre-Construction Documentation

Depending on the contract, the contractor may also need to submit a project schedule, a traffic control plan for any street or lane closures, notifications to affected residents and businesses, and pre-construction CCTV footage of the existing pipe condition. These aren't engineering deliverables in the traditional sense, but they're part of the overall submittal package that needs to be in order before work starts.

Why This Matters for Contractors

The SAWS consent decree work is competitively bid, and the contractors who win and execute these projects successfully are the ones who show up with their submittals in order. A sealed bypass pumping plan, properly prepared structural calculations, and clean CCTV documentation demonstrate to SAWS and the project engineer that you know what you're doing and that the work will be done safely.

If you're a contractor working on SAWS sewer rehabilitation projects or bidding on upcoming work and need engineering support for your submittals, that's a service we provide. From bypass pumping plans to structural calculations for CIPP and pipe bursting projects, we work regularly with contractors on the engineering side of trenchless sewer rehab in San Antonio.