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Sewage Overflows

Los Angeles Area.  Sewage Backup Through a Backflow Prevention Valve (Backwater Valve).  Technical expert in a case where flow from a trunk sewer flooded and severely damaged a million dollar home in Southern California.   The sewage leak was caused not by a blockage of the trunk sewer, but by the inadequate hydraulic capacity of the sewer. The major issues in the case involved whether having inadequate hydraulic capacity was within the normal Standard of Care and the adequacy of maintenance of an existing backflow prevention valve, which had been installed years before when the house was built, but the existence of which was unknown both to the Sanitary District and to the homeowner.

Coliform Contamination from a Sewer.  Provided advice on the significance of coliform organisms found in soil above a sewer in a law suit involving three homeowners.  The downstream homeowner attributed the coliforms to leakage of sewage from the upstream lots but sampling found that the coliform concentrations were lower in the soil near the sewer than on the surface of the plaintiff’s lot.  The most likely source of the coliforms at the surface was the plaintiff’s dogs.

Sewage Spill into a Store, San Bernardino County.  Forensic engineer in a case where a blockage of a City sewer caused sewage to flood a store in Southern California.  The City maintained that the blockage could not have been in the City line since other connected properties did not flood and since the upstream manhole showed no signs of having been flooded.   Investigations revealed that other nearby buildings were connected to a different sewer and/or were at a higher elevation than the flooded store.  It was also discovered that the person reporting that the upstream manhole showed no signs of having flooded was unaware that a different City crew had rebuilt the manhole subsequent to the incident.  When the incident was fully understood, the City paid the full amount of the claim.

Surfacing Septic Tank Effluent.  Reviewed voluminous documents and summarized the technical facts for the attorneys for two insurance companies, whose insureds were being sued by a downslope neighbor who claimed that their septic systems were discharging on to his property.  Interviewed the defendants.  Prepared questions to be put to the plaintiff during depositions.  Testified in a mediation hearing.

Flooding of Apartment Complex, Phoenix, AZ.  Provided expert technical advice on the probable causes of the flooding incident, the role that grease in the sewer system may have played, and the implications of a backflow preventer.  Prepared an extensive list of documents to be demanded.

Orange County City.  Provided expert witness services where a sewer was clogged by roots and backed up into a private residence.  The contractor hired by the City to maintain the sewer lines was obligated to inspect every manhole but failed to inspect the manhole where the root blockage occurred because the cover of the manhole was buried at a shallow depth in a planter in the street.  Expert testimony involved standards for use of sewer cleaning equipment.

Mobile Home Park Sewage Overflow, Mountain County, CA.  Evaluated the source and causes of a sewage overflow into a mobile home.  Analyzed the damages that were claimed to have been caused by the sewage overflow.

Homeowner v. City.  Evaluated a situation in which a private sewer serving several residences in a court was found to be backing up.  The City, which owned the public sewer to which the private sewer connected, inspected their portion of the piping and found that it was not blocked.  The City then required the homeowner to replace the private sewer.  After construction of the replacement sewer was complete, it was found that it again was not flowing freely.  The investigation revealed that the City sewer was not low enough to serve the private sewer and that the system had been built with a sag in it.

Defense Of A Sewer Maintenance Firm.  Served as an expert witness for a contract sewer operations firm that maintained the sewer system for a City in the Sacramento area.  A business that was flooded sued the maintenance firm as well as the City and others.  Developed information that showed that the maintenance firm had repeatedly pointed out the problems in the sewer system and requested that they be authorized to fix them for the City.

Water, Wastewater & Forensic Engineeer

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Bonneau Dickson
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