Dave - Do you have a geology background? It sounds like you have shallow well experience.
The fact that the productive fractures are quartz-filled is good news, it means the fracture system is old. When we frac oil wells, the fractures are vertical and the azimuth (compass direction) depends on the rock stresses. California is still tectonically very active (rocks layers pushing and pulling each other). Since the stress field is different now, compared to when the old fractures formed, any new induced fractures should cross-cut the old fractures.
Instead of drilling into one fracture, theoretically you could intersect 15 fractures at 10 GPM and have a 150 GPM well. The fact that no drillers in your area perform this service, probably means I have something wrong with applying it to your situation.
The fact that the rocks are very hard to drill is not really a problem. We couldn't drill through diamond-filled fractures because the diamond is so hard it can't be abraded (cut) by our bit. However, tap your wife's big ol' diamond with a hammer and see what happens. (I take that back, don't tap her diamond with a hammer. Lunkers may be able to give pond advice that eventually leads to a divorce. Fingerlings should make sure they don't give out that kind of advice.)
There are several problems I can imagine with the fracture treatment. In oil and gas wells (deep wells) the lithostatic pressure is high so the fractures form vertically. In near-surface fracturing, the new fractures may form horizontally between the rock layers. This still may not be a problem if your natural fractures are not also horizontal.
The biggest problem I forsee is keeping the fracture "in the zone". Our oil fracture treatments are usually limited by the burst strength of our steel tubulars. Our casing is cemented into the well with high-quality cement and allowed to set for a week before fracturing. We can get plenty of pressure at the surface to fracture the oil reservoir at depth. However, if you blow out through your casing, or fracture up your cement sheath into a water zone, then you have a good chance of ruining your whole well.
There is a way to run 420' of steel tubing in your well and use a packer to keep the pressure off of your well casing during the fracture treatment. The fracture pressure will seek the easiest path. I fear that in a shallow water well, the easiest path will be back up to the surface through your grout around the casing.
I know there have been a lot of high dollar groundwater remediation projects in California. They may have fractured some shallow wells in these projects to aid in the clean-up. If you know an expert in this field, you might ask them how they performed fracturing treatments (if they did any).
Tom - I hope that answered some of your questions. If you have a more specific question ask it in this thread (if that is proper PB etiquitte).
PB Regulars - I have an unusual pond-building situation. I have all kinds of idiot schemes to make it work. I need to get out and get some more survey levels to do a better design. Then I will open a new thread so you guys can help "de-idiotfy" my plans.
