Objectives:

Upon completion of this unit students should be able to: Calculate purge volumes for a well Read a drillers log to locate the screened interval, total well depth and dominant lithologies Choose appropriate sampling bottles, preservatives and sample collection methods Discuss strengths and weaknesses of different sampling methods, including bailers, peristaltic pumps, electric submersible pumps, and positive displacement (bladder) pumps

 

Reading for week 2:

Your readings and references this week come from several different sources:   1) Well logs- CSUS wellfield:   Scanned copies of the drillers logs from EXT, MW-1, MW-1A, MW-2, MW-2A, MW-3 and MW-3A are available at this link:   CSUS wellfield logs   2) Sampling guidelines and references:   California EPA, Department of Toxic Substances Control, 2008 revision, Representative Sampling of Groundwater for Hazardous Substances, 26 pp. with appendices.   DTSC sampling guidelines   USGS Water Resources Division standard methods:  U.S. Geological Survey, variously dated, National field manual for the collection of water-quality data: U.S. Geological Survey Techniques of Water-Resources Investigations, book 9, chaps. A1-A9.  Accessed online at http://pubs.water.usgs.gov/twri9A/, July 2012.   Ch. 2     Selecting equipment for water sampling Ch. 3     Cleaning equipment for water sampling Ch. 4     Collection of water samples Ch. 5     Processing water samples Ch. 6.0  Guidelines for field measurement of water quality   3) Low flow sampling papers: Several authors have compared results between traditional purging methods and low-flow sampling methods.  Note that the definition of "low-flow" varies!   - Gass, T.E., Barker, J.F., Dickhout, R., Fyte, J.S., 1991, Test  Results of the Grundfos Ground-Water Sampling Pump, National Water Well Association Proceedings of the Fifth National Symposium on Aquifer Restoration and Ground Water Monitoring, 13 p.   Gass et al., 1991   - Kearl, P.M., Korte, N.E., Stites, M, and Baker, J., 1994, Field Comparison of Micropurging vs. Traditional Ground Water Sampling, Ground Water Monitoring and Review, Fall issue, pp. 183- 190.   Kearl et al., 1994   Pohlmann, K.F., Blegen, R. P., and Hess, J.W., 1991, EPA Project summary, Field Comparison of Ground-Water Sampling Devices for Hazardous Waste Sites: An Evaluation using Volatile Organic Compounds.  EPA/600/S4-90/028, 4 p.   Pohlmann et al., 1991   Puls, R.W., and Barcelona, M.J., 1996, Low-Flow (Minimal Drawdown) Ground-Water Sampling Proceedures, EPA Groundwater issue, EPA/540/S-95/504, 11 p.   Puls and Barcelona, 1996

 

Activities:

Morning activities: Demonstration of bladder pump, peristaltic pump, and electric submersible pump.   We will divide into teams, and purge wells using three different methods.  Teams will use a bailer, a Grundfos 2" Rediflow submersible pump, a peristaltic pump, or a bladder pump.  Each team will record the flow rate of their pump, and estimate the purge time based on well volume.  The team that uses the bladder pump will place the pump in the middle of the screened interval and will use low-flow techniques.   Each team will record time, volume and field parameters until the pump has removed 3-5 well volumes, or the field parameters have stabilized.  Results will be recorded on a field data sheet and posted on the class web site. Field data sheet (extra copy)     Results from purging exercise- new files posted Saturday Aug. 5: MW-1, MW-2, MW-3 Afternoon activities: Barbara Dawson, Steve Schmidt and Toni Salas from the USGS Gamma program will demonstrate their well sampling protocol.  This will include identifying the well, setting up a clean zone, purging, and sampling for a suite of trace elements, nutrients, organic pollutants, and stable isotopes.

 

Assignment for week 2:

Assume that a train has derailed, spilling gasoline near the CSUS wellfield.  What purging and sampling method would you choose to sample for VOC's at the CSUS wellfield?  Use the data from Saturday's exercise to support your answer.   Answer this question in 5 pages or less (cover letter to the client and figures are extra, and may go beyond 5 pages).  Please double space your report, with normal margins and standard font (times or arial).  Refer to all figures in the text.  Citations are optional.  Use appropriate technical writing style, and include the following sections in your report:   Cover page (letter to the client):  You can alter the cover letter and company logo that you made last week.   Introduction and purpose   Hydrogeologic setting: geologic, hydrologic, land use, construction, hazards, etc. as appropriate.   Methods: field methods, laboratory methods, graphical methods, statistical methods as appropriate.   Results: summarize results.   Conclusions and recommendations Due date: Saturday, Aug. 11