Water Quality
BDD Water Will be Excellent Quality
General Description of the Water Quality of the Rio Grande at Buckman
The quality of the Rio Grande – LANL-origin radionuclides normally are absent from Rio Grande water and sediment at Buckman except during Los Alamos Canyon flash floods. These man-made radionuclides normally are detected or measured in the Rio Grande in amounts that are indistinguishable form background and are from atmospheric nuclear bomb testing decades ago. Flash floods flowing down the normally dry Los Alamos/Pueblo Canyon drainage to the Rio Grande occasionally transport much higher concentrations to the Rio Grande for a few hours.
The general water quality at the BDD Project’s point of diversion is highly variable. Although it is often relatively clear, the Rio Grande at Buckman may become less clear with suspended sand, silt, clay, natural organic material and microbes. However, neither the river water, the river sediments, nor the river bed typically contain toxic or hazardous substances in toxic or hazardous amounts, nor do they contain measurable radionuclides that are distinguishable from normal background.
However, storm runoff and other runoff such as a water line break can erode and transport contaminated sediments from LANL locations with contaminated soils into the bottoms of the Los Alamos/Pueblo Canyon and its tributaries, and then to the Rio Grande upstream of Buckman. Storm water flows have transported radionuclide and other pollutants to the Rio Grande. Concentrations of contaminants of public concern in the Rio Grande can, for a few hours at a time, exceed the concentrations associated with long-term health-based maximum average exposure limits. This is a matter of BDD Board and public concern, even though the health effects of these radionuclide contaminants are cumulative and chronic, not acute.
Studies have shown that the Rio Grande almost always has water quality that will comply with the most stringent standards advocated for contaminants of LANL origin. However, the BDD Board and Staff must be certain that storm water runoff from LANL is managed and regulated to ensure contaminants are contained on LANL property and do not reach the Rio Grande.
Five Facts that Project BDD Water Customers
The BDD Project will produce drinking water that complies with all safe drinking water standards based on five facts:
1. The quality of the Rio Grande –The Rio Grande does not contain LANL pollution except during major storm events, which result in significant flows Los Alamos/Pueblo Canyon to the Rio Grande.
2. Reduction of pollution in storm water – The BDD Board and Staff are successfully working with the U.S. Department of Energy (DOE) and LANL and with regulatory agencies to reduce pollution carried by storm water. By this action, they can reduce the migration of LANL-legacy contaminants into the Los Alamos and Pueblo canyons during runoff events to prevent pollution and these types of contaminants from reaching the Rio Grande.
3. Early notification system to stop diversions –The BDD Project intends to manage, and may temporarily cease, diversions if an early notification system indicates runoff from Los Alamos/Pueblo Canyon is bringing pollution to the river. The BDD is working with LANL to have this system designed, implemented and maintained.
4. Effective water treatment – Robust water treatment will remove LANL contaminants of concern.
5. Timely and transparent monitoring results – River and treated drinking water will be sampled, monitored and reported to the public. The BDD Board, as a matter of public policy, will provide timely, transparent data regarding river and drinking water quality to the public.
BDD Water Treatment Processes
The BDD Project Water Treatment Plant includes a series of conventional and advanced water treatment processes. The conventional processes remove the vast majority of contaminants. The advanced processes provide additional treatment and polishing of the finished drinking water. Conventional treatment processes include coagulation, flocculation, sedimentation and disinfection. Raw water ozonation improves the effectiveness of conventional treatment. Advanced treatment is provided by membrane filters, ozone and granular activated carbon contactors. Disinfection is accomplished with lower amounts of chlorine because the high-quality water does not need as much chlorine.
Click on the graphic below for more detailed information.
BDD Project Water Treatment Process – Step By Step
1. River water is diverted through a riverside structure with fish screens. Larger sand particles are returned to the Rio Grande and the water is pumped to the Water Treatment Plant.
2. Three presedimentation and raw water storage basins allow remaining larger particles to settle to the bottom for removal.
3. Ozone is added to oxidize organic material. Water is mixed with a coagulant, ferric choride, which causes even the finest particles to clump together.
4. Flocculation provides gentle mixing. The tiny individual particles collide, stick together, and become larger and heavier. Contaminants and impurities are swept up into the flocculated particles.
5. Plate settlers provide very still conditions to separate the heavier floc particles from the water by gravity. The settled solids, called sludge, is concentrated, dewatered in
a centrifuge, and hauled to the Caja del Rio landfill.
6. The clarified water is filtered under high pressure through membranes with extremely small pore size, 0.1 microns. This membrane filtration removes essentially all of the particulate matter, including particles that are much smaller than the pore size.
7. Ozone is again applied to the clean water. It oxidizes any dissolved organic material not previously removed and kills microbes. Organic compounds that may cause bad tastes or odors are oxidized (broken down), as are PPCPs (pharmaceuticals and personal care products) and EDCs (endocrine disruptors). Residual ozone is then destroyed.
8. The water passes through GAC (granular activated carbon) contactors. The oxidized organics are removed by the biologically active carbon, which also works as a “polishing” process.
9. Small amounts of chlorine and sodium hydroxide are added to disinfect the water and to correct the pH of the treated water. The finished drinking water is stored in a four-million-gallon tank. Two pump stations pump the treated water north and south to BDD Project drinking water transmission line connections to the City and County public drinking water distribution systems. Chlorine is added as necessary to have a very small amount of residual chlorine in the finished drinking water. This protects against any contamination that might occur.