Serving professionals in engineering, environmental, and groundwater geology
since 1957


Date: Tuesday, July 12, 2005
Location: Steven’s Steak House, 5332 Stevens Place, Commerce, California
Time: 6:00 p.m.-Social Hour; 7:00 p.m.-Dinner; 7:45 p.m.-Presentation

Cost: $30 per person with reservations, $35 at the door, $15 for students with a valid Student ID
Reservations: Call (949) 253-5924 ex 564, or email Brian Villalobos,
By noon, Monday, July 11, 2005

PRESENTER: Matt Werner
TOPIC: Dealing With Uncertainty Regarding The Chemistry of Drinking Water Wells—An Example From the City of Riverside


As engineering geologists we have learned—and readily accept—that there is inherent internal variability in the characteristics of geologic media. We’re not talking about laboratory error, here; we’re talking about spatial differences in property values that are just intrinsic to every formation, deposit, and aquifer. We can accept and understand this; yet, we struggle continuously with how to give our colleagues, “the engineers” the “one number” they always seem to want. Should we give them the “one number” that we think would support an adequately conservative design (how conservative should that be?), or should we give them a “plus/minus” or a “from/to” value? And just how much plus or minus should we add to be safe?

Groundwater retailers face the same problem. When groundwater is blended (like whiskey or wine grapes) its potability can be improved by diluting undesirable characteristics. Two non-potable flows, with different undesirable characteristics, can be blended to yield potable water. But groundwater has the same issues of intrinsic variability as other geologic media—concentrations go up and down over time. Minute-by-minute sampling of continuous feedstock flows is impossible, so what “one number” does one use for designing the blends, knowing that the number must be adequately conservative that the resulting water must never fail potability standards?

In Southern California, we can expect to see more water blending as population growth taxes our available groundwater resources. This presentation looks at the nature of variability in groundwater chemistry and several methods to characterize it for use in potable water blending.


Matt Werner began his career in 1973 in the Central Appalachians and Newark Basin evaluating seismic and fault hazards for nuclear generating stations and foundation conditions for pipe- and power-lines. He was transferred to California in 1978 to manage fault hazard studies for a proposed LNG off-loading facility at Point Conception. After changing firms in 1979, he led field teams evaluating geologic conditions and hazards at MX missile deployment areas in the Basin and Range. From 1981 to 1985 his focus was on tectonic, geomechanical and hydrogeologic conditions around mined openings proposed to house spent nuclear fuel in salt domes in the Gulf Coastal Plain. Between 1986 and 1992, he managed geologic mapping, drilling, seismic and geomechanical characterization to support Title I design of a proposed 50-mile tunnel for a Superconducting Super Collider in the chalk/marl of central Texas. For the next three years he mapped and tested abandoned homestead water wells in the Antelope Basin. In 2000, following a two-year stint writing successful proposals for government contracts and a three-year stint managing the firm’s Honolulu office, he returned to California and more technical endeavors. For the past five years he has evaluated groundwater conditions in the Bunker Hill Basin, with particular emphasis on groundwater use by the City of Riverside. Matt has a PhD from Penn State and is a California CEG and CHg. He is a Senior Project Director with 25-years of seniority at Earth Tech.