14 - Remove and Replace vs Trenchless Technology Costa Mesa Sanitary District
…an Independent Special District
Protecting our community’s health and the environment by providing solid waste and sewer collection services.
www.cmsdca.gov
Memorandum
To: Board of Directors
From : Scott Carroll, General Manager
Date: August 29, 2013
Subject: Remove and Replace vs. Trenchless Technology
Summary
The Board of Directors requested to receive an analysis report that compares the cost to
perform the traditional method of removing and replacing dilapidated sewer pipes versus
modern methods of using trenchless technology to rehabilitate sewer systems.
Staff Recommendation
Tha t the Board of Directors receives and files this report.
Analysis
Remove and replace, or excavation, is the oldest form of sewer system rehabilitation
available and will likely always have its place in the rehab il itation market. However, it’s
costly, time consuming and disruptive to motorists, businesses and homeowners.
The cost of excavating, removing and replacing 50 feet of main sewer line can range
dramatically, anywhere from $40 to over $300 a foot. The rea son 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 three to
five feet -deep may be replaced in a single day, whereas the same length of pipe located
eleven feet below ground could take several days to repair and add thousands of dollars to
the cost of the job.
ITEM NO. 14
Board of Directors
August 29 , 2013
Page 2 of 4
Obstacles that require remova l and replacement –such as porches, sidewalks, trees,
landscaping and driveways –will also require additional equipment, materials and man
hours
Overhead and underground utility lines, water supply lines and sprinkler systems are other
challenges that can ad d 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 determin e how many days it will take to comple te 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.
Trenchless technologies offer ma ny benefits over the traditional efforts of excavation
(remove and replace). There are many different types of trenchless technologies and it
seems that new technology is evolving every day. The following is a list of trenchless
technologies that are com monly used today.
• Cured -in -place pipe (CIPP)
• Pipe bursting
• Slip lining
• Fold and form
• Top hats and short liners
• Horizontal directional drilling (HDD)
Below are some benefits to trenchless technology.
1. Protecting the Environment : Like the name implies, trenchless technology uses a
set of methods, equipment and techniques to replace and rehabilitate pipes without
the need for excessive digging. Digging up pipes can wreak havoc on the
environment, killing plants, disrupting corridor s and causing a general mess. While
there are some special cases where digging can’t be avoided, many problems can
be easily fixed with trenchless technology that only requires the digging of one or
two small holes , if any.
2. Cost Effectiveness: Trenchless technology is often times much more cost
effective than traditional digging. This is due to several facts. First, trenchless
methods require less manual labor and heavy equipment , so fewer technicians and
equipment are needed to complete the job. It also r equires fewer hours, cutting
down on the time costs. Finally, the material used to line pipes, or that the new
pipes are made out of, is seamless and more reliant to the effects of nature. Since
the material is sturdier and lasts longer, the savings create d by trenchless
technology extends well on into the future. Relining cost can run anywhere
between $65 to $120 a foot and the cost for pipe bursting ranges from $45 to $105
a foot.
Board of Directors
August 29 , 2013
Page 3 of 4
3. Benefits to Infrastructure: When pipes that are laid underneath foundati on, roads or
other areas with structures already on them, it can be costly and possible damaging to
infrastructure to reach the damaged pipes. Trenchless technology allows pipes to be
either repaired or replaced without having to rip up any existing inf rastructure. This will
save additional costs that come from repairing infrastructure damaged during the pipe
rehabilitation process.
4. Time Effective Process: Trenchless technology processes are infinitely more time
effective than excavating . Jobs that would take days or weeks with excavation
processes take only a matter of hours or a day with trenc hless technology. This
means CMSD will be able to use rehabilitated main line as soon as it’s complete and
does not require using by -pass pumps for long perio d of time . In addition, traffic is
minimally disrupted for one day instead of several days or weeks and businesses will
not suffer due to lost patrons as a result of diverted traffic that is usually associated
with traditional excavation and replacement. And finally, the tranquility of
neighborhoods will remain because trenchless technology does not require heavy
equipment that causes loud construction noise as well as stirring up dust.
There are times when replacement needs to, and should, be considered. For example,
relining does not repair significant sags. While it can help smooth out a sagged section, it
cannot entirely repair it. Relining cannot correct grade alignment issues. It can help
improve the flow characteristics, but will not correct a revers e or improperly laid pipe
segment. Excavation and replacement is often a viable option when those situations exist
and require correction. Relining does not reround pipe as it conforms to the host pipe’s
original shape. Badly ovaled sections generally need to be replaced, as this is likely a
clear sign that the soil stability surrounding the pipe is in need of repair. Relining cannot
restore soil stability, but excavation can. Relining is not the right method for filling large
voids and gaps outside of the host pipes.
In conclusion, trenchless technology is a proven and cost effective method to rehabilitating
sewer systems. If the conditions are right, CMSD will use one of the trenchless
technologies identified on Page 2 of this report to rehabilitate and/or repair sewer main
line. In addition, staff will be watchful for new trenchless technologies . A good resource to
monitor the latest in t renchless technology is the North American Society for Trenchless
Technology (NASTT). Founded in 1990, NASTT represents more than 1,500 members
throughout the United States and Canada who all promote better and more responsible
ways to manage underground infrastructure with the latest technologies. NASTT puts on
an annual conference called, “No -Dig Show”, which is one of the largest trenchless
technology conferences in North America where professionals attend to learn new
techniques that will save money a nd improve infrastructure. The next No -Dig Show is
scheduled for April 13 -17, 2014 in Orlando, Florida.
Board of Directors
August 29 , 2013
Page 4 of 4
Strategic Plan Element & Goal
This item complies wit h Strategic Element 5 .0., Sewer Infrastructure , and Strategic Goal
No. 1.4, System wide Sewer Replacement and Repair Program.
Legal Review
Not applicable.
Financial Review
For the past two years, staff has used the trenchless technologies identified on Page 2 of
this report to rehabilitate District sewer system. The cost savings from these proje cts by
using trenchless technology instead of traditional excavation (remove and replace) are
identified below.
• Pipe bursting on Bristol Street – Saved $232,663
• HDPE sliplining on Irvine Avenue force main – Saved $623,913
• CIPP Santa Ana Avenue and 23 rd Street force mains – Saved $746,609
• Short lining and top hats for 123 pipeline sections – Saved $318,677
Staff estimates the District saved $1,921,832 using trenchless technology instead of
excavation.
Public Notice Process
Copies of this report are on file and will be included with the entire agenda packet for the
August 29 , 2013 Board of Directors regular meeting at District headquarters and on
District’s website.
Alternative Actions
1. Direct staff to report back with more information