Case Study: Subaru Wohlsen Construction

If this site sounds familiar, it’s because this is a follow-up to a case study that was done by Ben Iles. Obviously impressed with the work performed by Ben on the inside of the building, the customer called us out to perform work on the outside of the building. Here’s what we were able to find…..

PROBLEM: The customer did not know how the sanitary lines tied together outside of the building. Experiencing high water levels in the sanitary line leading out to the street. Also there was a lateral coming from an unknown source.


The customer exposed a few cleanouts at the center of the building where the sanitary line runs out to the street. It is from here that the lines would have to be investigated in all directions to map out the sanitary system and inspect the lines for the cause of the high water levels. For reference, this picture was taken facing south.

SOLUTION: A pushcam was used to inspect the various lines and located using the sonde and the RD.

Heading north, out towards the street, the high water levels were immediately recognized with the camera and the cause was found where the line ties into the public sewer main in the street. As you can see in the picture attached below, the main in the background (line running perpendicular to the line that the camera is in) and the line leaving the building (line that the camera is in) are both at the same depth. This means that any increase in the water levels of the public main would result in an increase in the water levels in the line leaving the building. Under normal circumstances, the line leaving the building would tie into the public sewer main coming from above, pitched downward and would not be affected by increased water levels in the main.

Heading west, along the building, the camera came to a cleanout that was not visible at the surface. The customer’s crew on site excavated this area to expose the buried cleanout and extend the riser to the existing grade.

Heading east, along the building, the camera came across another buried cleanout and a lateral coming from an area of the building with no known plumbing. The customer’s crew excavated this area and extended the riser of the cleanout to the existing grade and also exposed the lateral coming from an unknown source. Intent on finding where this lateral is coming from, the customer had his crew cut the lateral open so that the pushcam could be inserted into the line.

Heading south, along the building, from the cut open lateral, the pushcam came to a blockage in the line caused by stones. This spot was located using the sonde in the flower bed on the side of the building. Determined to continue the investigation of this line, the customer had his crew excavate this area with the intention of cutting the line open again. What they found caught us all by surprise. As they were digging, they began to expose the edges of a large concrete structure that no one knew was on site. By the angles of the corners it appeared to be decorative in nature and the line leading to it served as a drain. The crew on site were taking guesses that it was perhaps a pond or fountain that had been buried. They continued digging a bit trying to find the full extent of the structure but stopped to limit the amount of disruption to this landscaped area. It still remains a mystery as to what exactly the structure was.


With the information we provided, the customer benefited in multiple ways.

It was evident that the line leaving the building and heading out to the street was not pitched correctly. It would need to be relocated at a higher elevation to tie into the public main properly and eliminate the high water levels.

Two buried cleanouts were exposed giving the customer more access points into the line should problems arise in the future.

The lateral that was cut open can be capped to stop the infiltration of groundwater into the sanitary system.

The large concrete structure in the flower bed along the side of the building can be documented so it is accounted for if work is ever to take place at that location in the future.

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