City of San Luis Obispo - Utilities Department - Voluntary Service Lateral Prog -Technical

Evaluation Process

First of all, you need an access point somewhere on your property large enough for the camera equipment. A cleanout (3”minimum) is preferred. A plumber will use a small portable push type camera with about a one inch diameter head (black and white) with built in VCR for recording.

A local plumber of your choice will inspect the sewer lateral, keeping a log that will detail the defects found and at what distance from the access point. Obtain the video tape from your plumber and submit the tape and completed Voluntary Sewer Lateral Rehabilitation Program Application to the Wastewater Collection Section.

Submit the tape and application to: VSLRP City of SLO Utilities, 879 Morro Street, San Luis Obispo, CA, 93401. The tape will be evaluated and recommendations made as to what steps are needed to rehabilitate your lateral.

Roots

     Light - few fine roots entering pipe.

     Medium - roots entering pipe obstructing up to ½ of pipe diameter.

     Heavy - roots obstructing over ½ of pipe diameter.

Misaligned Joints

     Light - pipe is more than 80% clear at joint.

     Medium - pipe that is 60 to 80% clear at joint.

     Heavy – pipe that is less than 60% clear at joint.

Broken Pipe

      Light – pipe with single crack with edges still touching.

     Medium – pipe with single large crack or multiple cracks.

     Heavy – pipe with multiple large cracks.

Holes and Missing Pipe

Holes and missing pipe are described by size and shape of defect. For example - 2" x 2" piece of pipe missing, 1" diameter hole rusted through cast iron, etc.

Pipe Type

List pipe type and location where it changes. Our program automatically qualifies applicant if there is orangeburg pipe present.

Other Defects

Other defects include bellies, collapsed pipe, reverse grade, p-traps and defects that may affect service, but not qualify applicants for the voluntary program.

The applicants are notified of the defects present and staff makes a recommendation for repairs (if needed) and signs the customer up for the program at this time. A brief summary outlining the defects will be given to the customer.

Rehabilitation Methods Currently Available

There are three rehabilitation methods that are being used in this area for lateral rehabilitation. Conventional replacement, and two types of trenchless rehabilitation are approved in the City of San Luis Obispo, pipe lining and pipe bursting. Slip lining is not used at this time due to the size of the pipe (4 inch).

Conventional Replacement

Conventional replacement is the method used most. There are currently more contractors using this method and is usually the best method for replacement. Pricing is competitive with the other methods and there are pros and cons with this method.

Pros:

1.	Old pipe is removed from site and replaced with new plastic pipe;
2.	Lateral can be re-graded to increase fall and eliminate bellies;
3.	Pipe can be visually inspected by an inspector before being covered.

1.	Digging up pipe will result in some damage to landscaping and may require cutting sidewalks, driveways and street. Digging under retaining walls and other physical barriers may prove difficult and result in higher costs.
2.	Improper backfilling may cause pipe movement.

Pipe Bursting

Pipe bursting is a “trenchless” method that is becoming more common and is the preferred method in many situations. The process entails digging a pit at the start and end points of the replacement. A powerful winch pulls a cable with a cutting head breaking the old pipe and pushing it out of the way. The new pipe is pulled in behind the cutting head. Here are some pros and cons of using this method.

Pros:

1.	Minimal digging is required, resulting in virtually no landscape damage or cutting of sidewalks or driveways.
2.	Little impact to public right of ways and streets. A smaller access is needed in street for connection to sewer main.
3.	Pipe can be pulled under walls, driveways, and other physical barriers.

1.	Not able to correct grade issues. There are claims that bellies can be pulled out, but you can’t increase slope from point A to point B.
2.	Can’t be visually inspected. Our preferred method is to pour 5 gal. of water into lateral and then video inspect, looking for bellies.
3.	Should locate other utilities to prevent possible damage from ground displacement caused by pipe bursting.

Pipe Lining

Pipe lining is a process that uses the existing pipe as a “host pipe” to form a new pipe. An epoxy liner is inverted or pulled through the existing lateral and then cured with heat or by ambient temperature and creates a new pipe inside the host pipe. This makes your pipe structurally sound and watertight. There are a couple of processes available, but the result is essentially the same. Our experience has been with a sock liner wetted out with epoxy resin. It is pulled into its proper location and then inflated and left to cure with ambient temperature.

Pros:

1.	Only one excavation needed for most applications, usually within private property;
2.	No ground displacement or disturbance;
3.	Can line in existing pipe under walls, driveways and landscaping.

1.	Existing pipe can’t be collapsed. Should be fairly round (90% of original shape);
2.	Limited situations where process can be used.