GrokSurf's San Diego

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Posts Tagged ‘San Diego Formation’

San Diego Formation: new USGS deep monitoring well progress report November 2011

Posted by George J Janczyn on November 7, 2011

On October 20, USGS under contract with the City of San Diego began operations on a new deep monitoring well in the Chollas Creek vicinity near the intersection of Home Avenue and Federal Blvd. The well is the latest in a series of multiple-depth wells being drilled in selected areas of four coastal river basins for the San Diego Hydrogeology Project.

The primary objectives of the project are to develop an integrated, comprehensive understanding of the geology and hydrology of the San Diego area, focusing on the San Diego Formation and the overlying alluvial deposits, and use this understanding to evaluate expanded use of the alluvial deposits and the San Diego Formation for recharge and extraction.

Project Chief Wes Danskin writes about the latest developments:

November 1:

1. Hit the Otay formation, at 648 feet. Check out the photos of cuttings below; bet you can pick it out too. And we hit it within about 60 feet of where I thought.

And very pleased with my newest idea: poker chips to identify the formations; I can write on them, and they don’t dissolve or fly away like post-its.

The poker-picks you see here are: the San Diego formation identified via shells; and the Otay formation looks like Otay.

Each square sample box is 10 feet of drilling. The rectangular boxes indicate where we took a core.

Photo 1 below is 0-240 feet.

Read the rest of this entry »

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USGS set to drill next deep monitoring well in San Diego

Posted by George J Janczyn on October 15, 2011

The United States Geological Survey (USGS), in cooperation with the City of San Diego, will begin installation of the next deep monitoring well site. The drilling and well installation is being done by USGS Research Drilling Unit, which aids USGS scientists throughout the western United States. The USGS is part of the Department of the Interior, and is the primary federal agency charged with investigation of earth resources. The USGS does not have a regulatory function, so as our drillers say, “It’s all about the science.” It is common for the USGS to partner with other governmental agencies, in this case the City of San Diego, sharing scientific questions, skills, and finances.

The next deep monitoring well site in the San Diego area will be drilled to a depth of about 1500 feet, with 4-6 piezometers installed, each to a different depth. Water-level and water-quality information can be obtained from the piezometers. Pressure transducers will be installed to continuously monitor water levels; this real-time data is routed via satellite to a public website. The well site is designed to be a long-term investment for the next 50-100 years. Initially, it will provide information about the local geology and hydrology; later, it can be used to manage groundwater operations.

The well location is at the intersection of Home and Federal streets, just off SR94, just west of Interstate 805. Can’t miss us. Look for the big yellow drill rig with USGS on it. You are welcome to stop by anytime. The well site was chosen to be on the west side of the La Nacion fault, paired with the recently completed Chollas Park well site (SDCP), and about halfway in between the El Toyon (SDEP) and Aquaculture (SDAQ) well sites.

The drilling operations will begin on Oct 20, 2011, and will continue for about a month. The first 2+ weeks will involve drilling and coring. The 3rd week will focus on geophysical logging, interpretation to design construction of the 4-6 piezometers, and reeming the hole larger to accommodate the piezometers. The 4th week will focus on installing the piezometers. We drill 7 am to 7 pm, everyday, holidays included.

An additional source of water in the San Diego area may come from the San Diego Formation and the overlying, and possibly underlying, sedimentary deposits of sand, silt, and gravel. Prior to the USGS study, which began in 2001, the location, thickness, and water-yielding character of these deposits was poorly known. Since 2001, the USGS has installed 10 deep monitoring well sites throughout the coastal San Diego area; the sites are a key part of creating a three-dimensional view of the San Diego underground. This geologic, water-level, and water-quality information will help guide public agencies and consultants in how to best utilize the limited, mostly brackish, groundwater resources in the coastal San Diego area.

We’ll use mud rotary drilling technique, along with wire-line coring to collect undisturbed samples of sediment from selected depths. The piezometers are mostly 2-inch and one 3-inch PVC pipes which are installed to different depths. Each PVC pipe has 20 feet of perforations at the bottom to allow water to enter the pipe only at that depth. Sand is installed around the perforations and a thick clay-like grout is installed elsewhere. The end result is that we will have a nest of 4-6 PVC pipes that we can measure water levels in, and collect water quality samples from. The 3-inch PVC pipe extends to the bottom of the well bore and allows us to conduct a variety of future measurements, such as identifying changes in salinity throughout the entire 1,500 feet section of aquifer.

As usual, you are more than welcome to visit the site; bring your friends, Cub Scout packs, university classes, cameras. Just stop by; we will have an educational outreach area to help us synthesize the information and help communicate it to you. Or call me at the mobile phone below and we’ll set up a time to meet at the site.

Visit the project website

Wesley R. Danskin
Research Hydrologist
United States Geological Survey (USGS)
California Water Science Center
4165 Spruance Road, Suite 200
San Diego, CA 92101 USA
619-225-6100 office
858-663-6832 mobile

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What’s up with the Chollas Creek wells?

Posted by George J Janczyn on July 27, 2011

Wes Danskin, USGS Project Chief for the San Diego Hydrogeology Project, shares this update from the Chollas Park Monitoring Well installed under contract with the City of San Diego to study groundwater in that area of the San Diego Formation aquifer (for a page collecting all the project updates as well as other groundwater news click this link).

Depth of well screen (SC) and sand are listed

Well #6: SC: 29.5′-49.5′; Sand: 16′-56′
Well #5: SC: 140′-160′; Sand: 180′-119.5′
Well #4: SC: 330′-350′; Sand: 310′-372′
Well #3: SC: 520′-540′; Sand: 432′-585′
Well #2: SC: 760′-780′; Sand: 739′-814′
Well #1: SC: 1040′-1060′, 980′-1000′, & 920′-940′ w/a 40′ sump; Sand: 887′-1100′

The 6 piezometers at the site were developed, meaning the drilling fluid was removed. The process involves pumping air down each piezometer, which bubbles the water mixed with drilling fluid up and out. The aquifer then refills the piezometer with water, and the process continues until water-quality parameters (conductance, pH, and turbidity) stabilize, indicating that we are extracting only native water from the aquifer. The small amount of water in #5 means that it was not well developed. The low yield of #1 means that it took quite a while and some artful use of air, hose, and patience to get it developed. After winter rains next year, we will go back and see if we can develop and sample #5.

All piezometers have been sampled, except #5 which is dry, and #1, which is taking longer because of the low yield of the fractured bedrock. Sampling of #1 will be completed later this week. A broad range of water-quality constituents will be sampled including major and minor ions, trace elements, stable isotopes of hydrogen and oxygen and radioactive isotopes of hydrogen (tritium) and carbon (C-14), and volatile organics. By analyzing these data we can infer the source of the original recharge, when the recharge occurred, and whether human actions have affected the water. Because the general chemistry of water in the San Diego area like most basins is fairly similar, dependent on the rocks and derived sediment that the water is flowing through, we find it helpful to analyze trace elements and other minor constituents of water to determine of groundwater flow paths. It is rare for water districts or individuals to test for these constituents because they are commonly not viewed as a health or water-treatment hazard. Note, the radioactive isotopes are used for dating the time since recharge and are many, many times below a health hazard.

We also sampled a shallow well downslope from SDCP in order to compare our shallow piezometer data with it.

Water table appears to be at about 240 feet; Piezometers #5, #6 are both perched water tables.

Thought you might like to see samples of the water from each of the 5 piezometers we developed. You can tell #6 needs some more development; its a bit cloudy.

But we got great water out of #1, yeah! Getting water out of that fractured bedrock had me a bit worried for awhile.



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A brief talk about the USGS San Diego Hydrogeology Project

Posted by George J Janczyn on July 12, 2011

A few weeks ago I visited the site of the USGS monitoring well being drilled at Chollas Park. The well is part of the USGS San Diego Hydrogeology Project studying water quality, quantity, and flow characteristics in the San Diego Formation aquifer (click here for the story from the visit).

Here’s Project Chief Wes Danskin discussing the program with San Diego KGTV Channel 10 reporter Joe Little (apologies for the less-than-perfect camera work):


Also, here’s Joe Little’s report on 10 News.


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Chollas Park groundwater study: pictures tell the story

Posted by George J Janczyn on June 21, 2011

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).

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.

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

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′

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.

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.



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Site visit: USGS groundwater study at San Diego Chollas Park

Posted by George J Janczyn on June 7, 2011

Recently Wes Danskin, Project Chief for the U.S. Geological Survey (USGS) San Diego Hydrogeology Project, shared notes from his log (here and here) regarding installation of a monitoring well at Chollas Park that will be used as part of a study to learn about water quality, quantity, and flow characteristics in the San Diego Formation aquifer. Funding for the well comes from the City of San Diego.

Last Thursday I received an email from Danskin: “Stop by if you’d like, we’ll be on site for about another week completing the piezometer installation.” No need for a second invitation; the next morning I grabbed my camera and headed over to the project site.

The well is just west of Chollas Lake which itself is just west of the College Grove shopping center near the SR-94 freeway at College Avenue.

Several other visitors were already there, including a few members of the San Diego Association of Geologists (SDAG). 10News reporter Joe Little was there, preparing to interview Danskin for the evening news.

(all photos can be clicked for enlargement)

10News reporter Joe Little (left) prepares for the interview with Wes Danskin.

Wes animatedly talked about a new three-dimensional geologic map of the region that he’s been working on. No previous geologic studies in the San Diego/Tijuana area have produced such a map. According to the SDAG website (“Mapping the San Diego Underground”):

“A total of 91 wells, which showed stratigraphy older than Quaternary age, helped provide depth information to produce this 3D hydrogeologic framework model. This study relied on pre-existing GIS (geographic information systems) datasets including DEM (digital elevation model), surface geologic maps, drilling and e-logs, and literature references to wells or outcrops. Direct examination of USGS multi-depth wells provided the most reliable “ground truth” for geologic boundaries used in the model.”

Danskin explained there are three types of wells: 1) monitoring wells to identify water levels and quality and geology of the groundwater basin; 2) pilot production wells to determine the quantity of water flowing through the ground; 3) full scale production wells. For the San Diego study, the first two types are being used.

Continuing, Danskin said the San Diego Formation extends north-south from La Jolla to south of the border, and west-east from the ocean to the vicinity of the I-805 freeway. Groundwater has been extracted from the San Diego Formation for over 50 years. Sweetwater Authority has been distributing it to National City and Chula Vista.

“The important part about this well is that we’re actually able to get down into the hard rock,” said Danskin. “None of the other wells, with the exception of one near Qualcomm Stadium, were we able to identify this important part of the geologic story,” he said, noting that “the critical part of what we’re doing is defining how the geologic layers are arranged and that allows us to understand how the water moves through them.”

An interesting fact: using carbon dating they found that it could be up to 30,000 years since that groundwater was last in the atmosphere.

Little asked whether pumping and treating groundwater can be cost-effective. Danskin replied that Sweetwater Authority’s pumping of groundwater shows it is already cost-effective. It will gradually become even more competitive because the price of imported water continues to increase. It is becoming more attractive from a reliability point of view too, because we import up to 90% of our water from the Colorado River and the Sacramento-San Joaquin Delta, and both of those sources are climatologically, environmentally, and politically at risk.

Danskin said chances are that most of the water in the Formation will be salty and require reverse osmosis treatment…not as salty as the ocean but it may contain the same salt level as V-8 juice. Still he has an optimistic outlook about the project finding a reliable groundwater flow. “It’s taken about ten years,” he said, “but things are finally starting to make sense.”

A typical tricone drill bit.

Numerous soil samples are taken at regular checkpoints as the drill goes deeper.

Danskin discussing the various well locations in San Diego.


Here’s video I shot while Danskin discussed the project:


See also Joe Little’s report on Channel 10 News:


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San Diego files second lawsuit in groundwater dispute with Sweetwater Authority

Posted by George J Janczyn on December 21, 2010

The City of San Diego’s ongoing legal dispute over Sweetwater Authority’s project to expand groundwater pumping from the San Diego Formation aquifer has escalated with the filing of a second lawsuit.

The City’s first lawsuit, filed March 26, 2010, challenged Sweetwater’s certification of an Environmental Impact Report (EIR) and project approval (for background and a copy of that lawsuit see my October 28 report as updated December 8). The City alleged that its formally stated concerns about groundwater depletion/overdraft in the San Diego Formation, saltwater intrusion, land subsidence, brine discharge, and other issues were rejected or ignored by Sweetwater.

Subsequently, after some procedural errors in the approval process were discovered, Sweetwater Authority revisited its decision and again approved the project on November 10 (the U-T reported on that in this report).

San Diego’s newest lawsuit filed December 9 again challenges Sweetwater’s EIR certification and seeks to set aside Sweetwater’s November 10 action reaffirming project approval.

Significantly, going further, the new lawsuit also seeks the court’s declaration of San Diego’s Pueblo water rights in the San Diego Formation. Specifically, it asks:

For a declaration that the City was at the commencement of this action and now is the owner in fee simple of the prior and paramount right to the use of all the water of the San Diego Formation underlying the former Pueblo of San Diego, including all waters tributary thereto whether beneath the Pueblo or not, for the use of the City and of its inhabitants for all purposes and that Respondent Sweetwater and all other respondents have not and no one or more of them have any estate, right, title or interest in or to said waters, or any part thereof, or in the use of the same, or any right to take or use said waters, or any part thereof, save in subordination and subject to said prior and paramount right of the City.

Here is a copy of the new lawsuit:


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