Concrete Cloth Stormwater Infrastructure

October 05, 2017
What Are Your Trenchless Repair Options?

Posted by: John Hepfinger

Storm water and sanitary infrastructure repairs come with options — many options. Asset owners must consider the type of rehabilitation needed before even considering product brands. And because any major infrastructure repair can have a major impact on budget, it’s important to understand all the repair options available so that the best decisions can be made to receive both optimal performance and value.

For pipes requiring an upgrade in structural capability, there are generally four options worth considering; however, not every situation lends itself to all four types of rehabilitation.


The term polymer traditionally makes one think of a plastic, but geopolymers have the look and feel of cement with improved performance properties. Geopolymer products such as GeoSpray® are sprayed onto damaged infrastructure such as corrugated metal culverts, sanitary sewer pipes or manholes. Applied as a mortar, the products create a new structural pipe inside of the old pipe. As the mortar hardens into what is an essentially engineered stone, it provides a chemical- and abrasion-resistant surface that enhances the performance and the life of the original pipe. 

Why geopolymers?       

As a trenchless repair system, geopolymers can save time and cost through flexibility of application. The GeoSpray application process can start and stop as required by traffic control, flow issues, or even weather without loss of material performance or structural integrity. The product can be easily applied to large diameter pipes through either centrifugal casting or hand spraying.

Why not geopolymers?

The application process is generally confined to pipe diameters larger than 30” or above. The driving factor is the man entry required to stop any I&I prior to the application of material.


One of the oldest methods of pipe repair for storm and sanitary infrastructure, this is the method of sliding in and placing a plastic, polymer, or metal pipe within an existing structure. This repair method is generally confined to either circular or elliptical pipe, but sectional inserts can be custom manufactured to fit most any pipe shape.

          Why sliplining?

Typically a cost effective repair solution, sliplining is often chosen when it is not possible, or it is too expensive, to bypass the damaged area during installation. Most often this technique is used along a busy highway for culvert repair, while also effective in urban environments where access pits can be constructed. This method’s ideal use is to cover short distances with simple geometry in an easily accessible area.

Why not sliplining?

Sliplining loses out to other repair solutions when there is limited access to the pipe. If access to the target area isn’t easy, or there are permitting issues, this method can become very expensive. For example, when access requires disrupting a wetland along a highway, sliplining is not an ideal fit. Additionally, since you are inserting a smaller pipe within a larger pipe and grouting that annular space, sliplining creates a loss of hydraulic capacity.


Cured In Place Pipe, more commonly referred to as CIPP, is the most widely used technology of this group. It has been a popular and proven option for several decades due to its ability to work in very small diameter pipes (six or eight inches) as well as in larger diameter pipes. The repair product itself is made of polyester or a glass reinforced felt impregnated with resins. The tube is installed by being pulled through the pipe or by inversion before it is cured in place using water, steam or UV light. CIPP requires a bypass of the repair area in order to be installed.


Due to the exponentially increasing cost that correlates with the diameter of the pipe, this method is typically used with small diameter pipes. Its chemical resistance and durability in both sewer and storm water applications make it a viable option for both. There is a standard design methodology, which makes this a widely engineered solution.

Why not CIPP?

As previously noted, as the diameter of the pipe in need of repair increases so does the cost of the material. While the product can be installed around slight bends, it does have some difficulties handling irregular shapes. Planning is another major concern with this method. Once the installation process has begun, the installation must be seen through to completion. This makes planning around inclement weather and public disruption a major priority as any disturbance that may delay work could mean completely starting over. Often times there may be too many risks involved between cost and potential interruptions to consider this option.         


Spiral Wound (SPR) is perhaps the least used of these four trenchless pipe repair options and is typically used only in niche markets when the other options are not available. The process works by sending a mandrel-like winding machine that spins a flat sheet of either polyethylene or PVC into place along the pipe walls, creating a pipe within a pipe. Depending on the flow of the damaged pipe, a bypass may or may not be required with the SPR method. Once the polyethylene or PVC lining is in place, a grout is applied to secure the lining and fill in the annular space.

Why SPR?

As mentioned, the materials used in SPR meet the standards in some niche markets and also provide good quality chemical resistance as a trenchless repair. It can effectively be applied to oddly shaped spaces, and the method can get into places with more complicated geometries that methods such as sliplining cannot. Additionally, if the flow of the pipe is not too high, this method may be used without bypassing.

Why not SPR?

As the most expensive option of the four, SPR typically loses out to other options.

While there may be benefits of working with one particular repair manufacturer over another, the most important part of any repair is that the method and/or product being used adequately solves the damage and provides functional and safe infrastructure.

Still have questions about which trenchless pipe repair method might be best for your next project? Feel free to contact our engineers at [email protected] to discuss your options. To read more about our Geopolymer products, visit

Category: GeoSpray Geopolymer
Tags: Geospray , Geopolymers


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