Curb boxes don’t see daily use, but keeping them in good working order is critical for waterline repairs and shut-offs. Acidic soils can make that a challenge.

The challenge is that many areas across the U.S. — including the East Coast, South, Upper Midwest and Pacific Northwest — have acidic soil that rapidly corrodes cast iron infrastructure. Soil with a pH of 6 or less is considered acidic.

While soil can typically range in acidity from 2.5 to 10, pH levels of 5 or below can lead to extreme corrosion rates and premature pitting of buried cast iron infrastructure and curb boxes. Even coatings intended to protect cast iron begin to dissolve when soil pH is around 4, which leaves curb boxes vulnerable to corrosion.

“We have an electrolysis problem in the acidic soil here, and it eats up the pipe. Even though we put a stainless steel rod on [the curb box], that stainless steel rod doesn’t do any good when you have a pipe that’s rotting out where we can’t get to it,” says Bob Krueger, a systems operator at Waverly Sanitary District in Menasha, Wisconsin, which had hundreds of curb boxes in need of repair.

Fortunately for municipal waterworks departments, an easy repair that takes minutes can dramatically prolong curb box service life using polyurethane parts that won’t corrode in acidic soil. 

Because corrosion can also compromise the entire curb box/curb stop apparatus, a growing number of industry professionals are also turning to replacement kits that utilize polyurethane, which can make the whole system impervious to corrosion and premature replacement.

Prolonging life

The more acidic the soil, the sooner cast iron curb box caps will corrode, making it difficult or even impossible to access the water shut-off valve. Typically, the curb box cap will “freeze up” due to corrosion. Then when a technician tries to remove the cap, the nut or cap will break. 

The common curb box cap repair procedure is to dig a wide, deep hole around the broken equipment, cut the cast iron tube below the affected area, splice an extension by either manually threading the broken pipe and using a threaded coupler or by using a coupler with two setscrews, and then replace the cast iron top. However, this takes hours and still exposes the curb box to the possibility of corroding again in a few years. 

If acidic soil corrosion has affected the curb stop (the lower portion of the curb box that houses the water shut-off valve), then a more extensive repair is required. This often requires a crew using heavy equipment to dig out and replace the entire curb box apparatus, adding hours of labor.

In response, Krueger and the Waverly Sanitary District turned to the Speedy Sleeve, a noncorroding, quick-repair curb box product made of polyurethane. It’s made by Argonics, a Michigan-based design and manufacturing firm specializing in high-performance materials.

The product enables repairs of the corroded or broken top portion of curb boxes in minutes to provide access to the water shut-off valve, and it was specifically engineered for extended use, low maintenance and easy installation. It doesn’t rust or corrode like cast iron, won’t shatter or crack like plastic, cannot be damaged from impact with lawn mowers or plows and remains pliable even in extreme cold.

The sleeves are 6 to 18 inches in length with two small fins. The top opening is sealed with a cap that will never rust and seize.

Installation is simple: Just cut off the top of the old pipe, and then slip on the sleeve. To get a snug fit at an appropriate level — above or below ground — dig out around the pipe and then tap down with a hammer. The fins stabilize the device in the soil so it won’t twist or move due to frost heaving. They are always easy to locate because the cap is designed with an embedded magnet.

After successful use of the sleeves for quick repairs, the Waverly Sanitary District also utilized Speedy Sleeve poly curb box systems to replace a large number of systems that had corroded and were no longer viable. Corrosion was so significant that the district was replacing its curb boxes every five to 10 years.

When used with off-the-shelf PVC piping, the Speedy Sleeve curb box systems replace the entire curb box/curb stop apparatus.

“We were looking for something with a much longer life span than 10 years,” Krueger says. “We like the curb box because it’s a noncorrosive product and because of the ease of installation. These boxes installed easily, they’re easy to adjust and they don’t rely on metal threaded couplings.”

The simplicity of the design enables adjusting the height of the Speedy Sleeve repair kit and complete curb box system to the desired final grade in seconds. Both are engineered to be installed with ease in concrete driveways and sidewalks.

Unlike proprietary cast iron repair tops and bottoms, which often vary in thread pitch so they cannot be mixed and matched, the Speedy Sleeve units have a universal design that accommodates most industry variations and adjusts to height. This minimizes required inventory space.

With the life span of aging municipal waterworks infrastructure being shortened by acidic soil conditions in many parts of the country, proactive supervisors are increasingly extending service life and reducing maintenance by turning to polyurethane alternatives that will not corrode.