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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.

Septic Systems

Alameda County, CA.  Served as expert witness in a case involving the failure of a leach field of a septic tank system at a very large single family home shortly after the leach field was constructed.  While channeling the overflowing sewage away from the residence, the home owner contracted Giardia Lamblia and was banned by health officials from working for six weeks at his normal job, which involved food preparation.   Investigations revealed that the Contractor had not followed the requirements of the County Health Department and had constructed less leach line than was offered in his proposal.

Failure to Disclose, Leach Field Failure, San Diego, CA.  Provided technical advice to an attorney representing sellers of a home who were sued for failing to disclose problems with the leach field.  The Sellers had a problem with the leach field a year before selling the house and had had it repaired.  The Buyers lived in the house for a year before there was another problem with the leach field.  The problem occurred when the average monthly rainfall was double the normal amount.  Issues included statistical probability of leach field problems in rainy years, the cost of repair and the Standard of Care.

Cesspool Failure, City of Los Angeles.  Advised on the failure of a cesspool at an expensive private residence in the City of Los Angeles.  The purchaser of the residence was not informed that an older cesspool had failed and had been filled in.  Attempts to construct a new cesspool were unsuccessful and the house had to be vacated.

Hepatitis Infection from Surfacing Septic Tank Effluent, Marin County.  Provided expert technical advice on a suit where the children of a farm worker were alleged to have contracted hepatitis from exposure to surfacing septic tank effluent.

Death from Septic Tank Dry Well, Ventura County.  Unbeknownst to the present homeowners, the septic tank system of their home was equipped with a dry well, rather than a conventional leach field.  The dry well was about 3-feet in diameter and 25-feet deep.  This type of disposal facility had been permitted until approximately 1970 by the local building officials.  The top of the dry well was covered with a concrete cap, which apparently deteriorated over time.  When the six year old child of a neighbor walked on the concrete cap, it collapsed.  The child fell into the dry well and drowned.

Inadequate Septic Tank Inspection, Los Angeles County, CA.   As a requirement of the lender, the septic system serving a house for sale was inspected by a septic system service company.  Two weeks after the new owner moved in, the system failed.  A second septic system service company noted that the earlier inspection was deficient.  Provided technical advice on the standard of care for inspection and servicing of septic systems.

Standard of Care

Reviewed the Standard Of Care in the design of a wastewater system for a food processor in the Sacramento River valley.  Discovered that the design engineer had not included a solids removal unit process in the aerated lagoon wastewater treatment system, thus the system could not meet the required discharge standards.

Sewer Design Standard of Care.  Expert witness on a case involving delay claims caused by problems with the design of the sewer system for a large apartment complex.  Prepared a certificate for use in filing suit against the design engineer.

California Landing Stormwater Pump Station Flooding.  Served as technical expert on a law suit involving the failure of a stormwater pump station in a subdivision in the lower East Bay.  The station flooded out when excessive flows reached the site through a gap in the levees along the adjoining stream.  Concluded that the design of the pump station met the Standard of Care and that the unforeseen, excessive flows were the cause of the problem.

PCE (Perchlorethylene-Laundry Solvent) Contamination

Bonneau Dickson has served as an expert witness on several cases in which it was alleged that public sewer systems had allowed perchloroethylene (PCE) that was discharged by dry cleaning establishments to contaminate the groundwater.  Topics of interest were design standards for sewer construction, leakage from various types of sewer pipes, and colmation (the tendency of sewage to seal the leaks).

Other Forensic Engineering

Residential Leakage and Drainage Problems.  Investigated leakage and drainage problems in approximately 200 houses.  About a dozen of these cases resulted in legal action, in which Bonneau Dickson was used as an expert.

Expert Witness, Failed Stormdrain Piping.  Serving as an expert witness in a case in which plastic storm drain piping collapsed.

Wastewater Treatment Plant Claim.  Evaluated proposed corrective measures in a $5 million claim in which a wastewater treatment plant failed to perform as intended.  The levees around earthen storage lagoons leaked because the design did not incorporate the recommendations of the geotechnical engineer.  An innovative land-application nitrogen removal facility created an extreme mosquito problem.  A gravity pipeline that was pressurized as a part of the project leaked excessively.

Mobile Home Park Contamination, North Bay.  Technical expert on a case north of San Francisco Bay where the residents sued the owner alleging that the water supply was contaminated and that they had been exposed to sewage.

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