THE COHEN GROUP
  Environmental Health & Safety Consulting Services

The Cohen Group Newsletter - Volume 8  Issue 3, Article 4.  September, 2006

  Sewage Backups and Backflows – Hazards and Responses
Julie V. Wellings, CIH

It can be a building manager’s worst nightmare – with no warning, sewage begins oozing out of the plumbing fixtures and/or floor drains. The problem may be a sewage "backup" (obstruction within the building’s plumbing system or "lateral" sewer line) or a sewage "backflow" (backup from the sewer "main", with an absent or failing backflow prevention device in the building’s sewer "lateral").

Examples of recent sewage incidents where we have assisted with response include: a construction site where heavy rains caused a backflow of sewage in multiple drains within a building under construction; a pharmaceutical facility that experienced a sewage backflow in many of its laboratories from actions taken by an "upstream" commercial facility; and concurrent backflows in a community of single family homes. Whatever the cause, timely and effective response will be needed to protect both property and people. Materials can become contaminated and some may need to be discarded. People may be exposed to contaminants in the sewage, most notably biological agents.

Water released from plumbing systems are generally categorized as one of the following:

Category 1 - Clean Water: Water that does not pose a substantial harm. Examples include water from broken supply lines, toilet tanks, bathtubs and sinks where no chemical additives or contaminants are present.

Category 2 - Gray Water: Water that contains some chemical, biological and/or physical contamination and has the potential to cause discomfort or sickness if consumed. Examples include overflows from dishwashers, washing machines, and toilet bowls with urine only, including household cleaning or treatment products.

Category 3 - Black Water: Water that is grossly unsanitary, containing pathogenic agents from sewage or other sources and likely to cause discomfort or sickness if consumed. Examples include overflows from toilet bowls containing feces, sewer backups (toilet originated from beyond the toilet trap) and sewer backflows (originating from beyond the building’s sewer "laterals".) Black water may also contain chemical contaminants.

Where sewage is involved, the most likely contaminants are enteric bacteria and viruses, i.e., biological agents that may be found in the human digestive tract. Certain organisms are considered "indicators" of human or animal waste, including E. coli and Enterococcus species. However, other disease-causing organisms or agents may also be present.

In general, contaminants may enter the body by three routes: 1) inhalation of airborne contaminants, 2) ingestion of contamination from hands, face, food, drink or smoking materials, and 3) entry of contamination through skin, lesions or mucous membranes. Exposure by all three routes should be prevented, but the most significant route of exposure for enteric bacteria and viruses is through accidental ingestion of contaminants.

In general, acute effects from exposure may include headache, nausea, fatigue, dizziness, fever, rash, and digestive disturbances. Symptoms usually subside within a few days, but longer term and more serious illness may occur. The severity and duration of health effects from enteric bacteria and viruses varies with the type and extent of exposure and the individual’s health status and susceptibility.

The bottom line is that, because of the potential health hazards, only properly trained and equipped persons should respond to actual or perceived "black water" or sewage spills. In-house maintenance staff should be utilized for small spills only (e.g., no more than 10 gallons), should receive training in sewage spill response, and should be provided with personal protective equipment during cleanup work. A professional remediation company should be used for larger releases of "black water" or sewage, and for smaller spills where in-house staff has not been properly trained or equipped.

Building managers should develop spill response plans in anticipation of possible sewer backups or backflows. If you do not currently have one, we can assist in developing a site-specific plan for your building or facility.