Lab Work – Testing the Waters

The District crew is constantly monitoring the water coming out of each treatment facility to make sure it is clean enough to go back into the nearest stream or creek. The District has a small laboratory to conduct the more common tests on site. A local lab is used for more sophisticated and specialized testing.


On-site testing includes:

BOD (Biochemical Oxygen Demand)
BOD measures the amount of oxygen that is used up or depleted by the bacteria, chemicals and other contaminants that are in the wastewater. Since oxygen is needed in our creeks and streams to sustain aquatic life, oxygen must be replenished through treatment before the treated reclaimed water can be released back into the environment. The higher the BOD content coming into the plant, the more energy it takes to treat and restore oxygen into the reclaimed water during the treatment process.  The reclaimed water coming out of the treatment plants have a BOD of approximately 10 milligrams per liter (mg/L) to 45 mg/L depending on the dictates of the particular NPDES permit and the type of treatment.

TSS (Total Suspended Solids)
TSS is the solid particles that are suspended in wastewater that do not settle out. In wastewater, TSS is mostly organic in nature and can serve as refuges for harmful bacteria and other microorganisms. TSS can limit sunlight from reaching aquatic plant life, which is required for photosynthesis, a natural process essential to life.  Therefore, suspended solids must be reduced from any water returned to the environment.  District permits require that the reclaimed water coming out of the treatment/reclamation plants have a TSS of approximately 15 mg/L to 80 mg/L depending on the dictates of the particular NPDES permit and the type of treatment.

pH
The pH value, measured by a pH meter, identifies the composition and environment of organisms in the water. The pH scale ranges from 0 to 14. Pure water is said to be neutral, with a pH close to 7.0. Solutions with a pH less than 7 are said to be acidic, and solutions with a pH greater than 7 are said to be basic or alkaline. District permits require that the reclaimed water coming out of the treatment plants have a pH of approximately 6.5 to 8.