Sewer Repair: Excavation vs. Reline
By: Patrick Hooper
Currently, the two most common methods of repairing a damaged sewer line is a Full Line Replacement, and what is known as a Reline, sometimes referred to as a Sleeve. If an inspection reveals serious issues with the sewer lateral that can only be remediated with a full replacement or repair, these are the two methods I most often consult my customers on.
An excavation is a pretty straight forward option in which the yard is dug up and the old line is removed and replaced, usually, with either SDR 35 or SCH 40 PVC pipe.
A reline is often referred to as a “no-dig” trenchless sewer repair, as it requires very little, if any digging. It involves re-lining the interior of the existing damaged sewer line with a seamless liner. The new sewer liner can sometimes be installed through an existing access point, called a clean-out, but often times requires the excavation of a small 2′ x 4′ area, normally in the foundation, but sometimes in the yard.
There are advantages and disadvantages to each method, which I’ll discuss shortly. If you are ever offered a quote for a replacement or repair by an estimator who offers one or the other, you need to be certain you are choosing the option that is best for you–not what’s best for the salesman.
Cost
Many assume that a reline is a less-expensive option than an excavation and replacement, but that’s not always the case. As a relatively new technology, the cost of the materials for relines are only manufactured by a hand-full of companies, making these supplies very expensive. As to which method is most cost-effective depends on a number of variables.
The cost of excavating, removing and replacing 50 feet of main sewer line can range dramatically, anywhere from $2,000 to $15,000+. The reasons for this variance is due to the circumstances of the conditions under which the work is to be performed.
The depth of the pipe to be replaced is one major determination of the man hours and equipment necessary to complete the job. A 50-foot-long sewer line that is only 3- to 5-feet-deep may be replaced in a single day, whereas the same length of pipe located 11-feet below ground could take several days to repair and add thousands of dollars to the cost of the job.
Obstacles that require removal and replacement–such as porches, sidewalks, trees, landscaping and driveways–will also require additional equipment, materials and manhours. Note: Removing large shade trees from a yard can also be extremely impactful to the long-term expense of cooling a home during the summer months–something most homeowners never consider.
Overhead and underground utility lines, water supply lines and sprinkler systems are other challenges that can add to the time and expense of excavation and replacement of a sewer line. An additional and very important consideration is the time of year. Jobs are normally bid based on “days of labor.” When working outside, the amount of available daylight can determine how many days it will take to complete a job. A one-day job in July–during which there is adequate daylight until 8:30 or 9:00 pm at night–will easily become a two-day job in December, when it gets dark before 5:00 pm. If I feel a sewer line can last long enough, I advise my customers to put repairs off until the summer months, as it can translate to thousands of dollars in savings.
During a reline, most of the above issues are not a problem or concern. Since the work is usually done at one location from one relatively small access area, line depth, obstacles and time-of-year don’t usually come into play. Depending on the company, the cost to reline 50 feet of sewer line (in Ohio) is roughly $9,000 to $13,000, regardless of depth. So, if you have 50 feet of line that is situated less than 5-feet-deep and there are no obstacles above or around the site of the line, excavation and replacement is much more cost-effective. On the other hand, if your 50 feet of sewer line is 10-feet-deep and a tree and a driveway will need to be removed in order to access the line, a reline makes much more sense.
Extent of Repair
If your main sewer line runs 50 feet from your house to the sidewalk or right-of-way, and then goes another 20 feet under the street before connecting to the city sewer–a reline would be a preferable repair option. Most plumbers and excavation companies do not like to work in/dig up the street, as it requires additional permits, licenses and liabilities, as well as additional expense. So, while a line excavation/replacement can only replace 50 feet of a 70 foot line, a reline can repair the entire length of the pipe.
Additional Considerations
Digging up a yard creates a huge mess–one that can last for more than a year. The general rule of thumb is that once an excavated area of earth is back filled, it will leave a mound above grade that will equal half the depth of the hole. In other words, a 10-foot-deep trench, when filled in, will leave a 5-foot-tall mound of dirt. It typically takes more than 12 months for the mound to settle back down to grade. The cause is that prior to excavating, the soil is extremely compacted under literally tons of earth. When dug up, the dirt is aerated and “fluffs up.” Accordingly, when the earth is put back in the hole, it won’t all fit and requires time to compact back down. So, if you don’t want to deal with a mess like this, a reline is a good option for you.
One important point to make about relines is that they are not always possible to perform. Sewer lines that are completely collapsed, have severe punctures with sharp and jagged pieces of broken pipe, excessive erosion, severe offsets, compression, etc. can eliminate a reline as a repair option. However, given the right circumstances, a reline might be the perfect option for your repair.
You can review a short, animated demonstration of how relines are applied by clicking on the link below.