GrokSurf's San Diego

Here’s the latest from Wes Danskin’s log on the USGS groundwater study at San Diego Chollas Park (previous log entries on this study are here).

WHAT’S NEW
Done drilling, chose depths for wells (piezometers–pressure sensing wells), installed 2-inch PVC piezometers, and are developing of them as I write this. Decided to include photos of each activity so you don’t have to read all this, just view the photos.

CORING TELLS THE STORY
Hit bedrock (Santiago Peak volcanics at 877 feet). Core at 895 feet is shown below. Many fractures are present

PICKING THE DEPTHS OF PIEZOMETERS
Based on geophysical logs, drill cuttings, cores, pore water chemistry, geologic mapping, evolving concepts of groundwater flow, likely constraints to developing a water supply, defining the yuck factor of Chollas water, taking advantage of evaporating Chollas Lake water … one of the more difficult things I do. You definitely get your money’s worth from the Chief Scientist on the project (me).

Well #1: 1040′-1060′, 980′-1000′, & 920′-940′
Well #2: 760′-780′
Well #3: 520′-540′
Well #4: 330′-350′
Well #5: 140′-160′
Well #6: 30′-50′

DEVELOPING WELLS
Send air down the wells to force water and left-over drilling fluid up and out. In the photo you’ll see water being ejected from one of the wells.

As we extract water/drilling fluid, the aquifer replenishes the well water, which eventually ends up cleaning the well of our drilling effects. We monitor clarity of the water, pH, conductance, and temperature to known when we have removed drilling-related water and fluids and when we have native ground water. Great news is that the fractured well shown in the photo above makes water, not much, but makes water via those fractures.

NEXT STEPS
Sampling the wells for water quality.
Installing a vault to protect the wells.
Installing water-level monitoring equipment, and satellite link.
Putting the information on our website.

Whew, I’m exhausted; almost done.

–wes