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Water Quality

  • New Groundwater Sustainability Requirements - CA

    Tools for New Groundwater Sustainability Agency’s (GSA)

    In accordance with guidelines created under the Sustainability Groundwater Management Act each groundwater basin in the State will have an Agency (GSA) dedicated to to acquiring and reporting specific groundwater data and parameters for each well. For more specifics on Sustainable Groundwater Management, you can visit the CA Dept of Water Resources.

    EnviroTech is a Company that provides products and instrumentation for acquiring that data, including the tools needed to satisfy many GSA requirements. This series is dedicated to the primary tools any GSA will need.

    To start all wells will need to be measured for depth and possibly datalogged. Here are two tools of the trade.

    1) Water Level Meters

    There are a host of meters to choose from but it can be assumed a GSA will require a water level meter with depth. Here is the most cost effective and efficient of all the brands available. Other excellent brands can be obtained through our website or catalog.

    Featured Product: Coaxial Cable Water Level Meter
    The Solinst Model 102 Water Level Meter is designed to measure groundwater levels, especially in small diameter (pumping ports) and deep wells. It is light and portable. The P10 Probe is recommended to provide enough weight in deeper wells. This is the go-to tool for GSA work.

    2) Leveloggers

    Also know as dataloggers or transducers, these tools will measure rising and falling water levels in a well over time at pre-programmed intervals.

    Featured Product: The Solinst Levelogger Junior Edge is an excellent cost savings way of collecting data from shallow environments. All you need is basic communication package then drop down a well, retrieve then download the data.

    If you have specific questions regarding any of these products or need help choosing the right tool for the job, don't hesitate to contact us.

  • How Has 2016/2017 Winter Rainfall Impacted Groundwater?

    2017 began with one of the wettest starts on record. While we saw reservoirs filling up and rushing rivers in California earlier this year, groundwater levels reflected the differing hydrologic conditions of individual groundwater basins. Although water levels in shallow basins may quickly show marked improvement, deeper, severely depleted groundwater basins may take years to recharge.

     

    Although Spring 2017 groundwater levels have mostly recovered from last year, they have not  yet recovered to pre-drought conditions in many areas of the state.

     

    When compared to 2016, spring 2017 groundwater levels are higher in many areas of the state. However, the impacts of the drought can still be seen when comparing spring 2017 groundwater levels to 2011 (pre-drought conditions). More information is available in this Spring 2017 Groundwater Level Data Summary from the State of California Natural Resources Agency.

     

    If you are going out in the field, here are more Resources for you:

     

  • Stormwater Sampling Season

    Here comes the rain! The rain season has officially started, and that means more storm event monitoring on construction sites.  Are you ready?

    The EPA Construction General Permit requires turbidity and pH measurements in the field, so you will need to have a pH meter and turbidity meter that are working and in good condition. If you are looking for a good Turbidity Meter - check out the Hanna 98703 Turbidity Meter.

    Both the pH and turbidity meters will need to be calibrated before being used to ensure measurements are accurate. The state Department of Health requires surface-water treatment plant operators to calibrate them at least as often as recommended by the manufacturer. If your last calibration was more than three months ago, it’s probably time for a check-up.

    If you need help with calibration, or finding the right equipment for the job, EnviroTech can help!

    If you are in need of groundwater instruments, there are several manufacturers available for you to choose from. In our 30+ years in the field we have found that MyronL Company continues to produce high quality and exceptionally durable field instrumentation. The Ultrapen is of the most durable water quality meters and is setting the standard in easy to use handheld instrumentation.

    For more resources you can find the EPA’s guide to Developing Your Storm Water Prevention Pollution Plan and EnviroTech's specifications on Groundwater Sampling.

  • New Emerging Contaminant

    An emerging contaminant is a recently discovered compound that may, or may not, represent a risk or danger to public health.  As in this case, they are often compounds that the EPA is currently investigating. I learned about this compound at a public Restoration Advisory Board (RAB) meeting held at the former Mare Island Naval Shipyard located in Vallejo, California.

    As a brief prelude, Mare Island was an active Naval shipyard from 1854 until its decommissioning in 1993. Over 500 ships, submarines and support vessels were built at this facility during a time when very few environmental regulations existed and, as a result, now this former shipyard is undergoing environmental cleanup in conjunction with ongoing transformation into a thriving futuristic residential and business community.  As part of this transformation the US Navy has a defined process known as the Base Realignment and Closure (BRAC) program. This program allows the safe transfer of military installations into the hands of the public domain and further oversees environmental cleanup operations. For more information on the cleanup and water quality instrumentation used at Mare Island and the RAB public meeting process for other former naval facilities such as Hunters Point, Treasure Island, and Alameda click here.

    Having attended these RAB meetings for decades, I give credit to the RAB members and Navy BRAC teams for their oversight and attentive involvement.

    One BRAC team member gave an interesting presentation defining a new emerging contaminant compound, per and polyfluoroalkyl Substances (PFAS's). As taken from the EPA website (PFAS’s) are a diverse group of compounds resistant to heat, water, and oil. For decades, they have been used in hundreds of industrial applications and consumer products such as carpeting, apparels, upholstery, food paper wrappings, fire-fighting foams and metal plating. You can find information here.

    The EPA has established what is called a lifetime health advisory (LHA) exposure limits at 70 part per trillion (PPT) in drinking water meaning a person should not be exposed to a level greater than that. Comparatively, a PPT is an infinitesimally small amount; think one second out of 30,000 years.

    The Navy is undertaking an initial evaluation that will implement a groundwater investigation and sampling project at the former Mare Island Naval Shipyard to evaluate the potential presence of PFAS’s in ground water. The sampling calls for specialized protocols to redevelop some existing wells and avoid cross contamination or introducing PFAS’s in the sampling process. Further investigation shows the Navy’s has conducted similar studies of this nature at military installations some of which show the presence of PFAS’s at levels exceeding the EPA lifetime threshold. More information on this and how the Navy is responding.

    The presentation outlined the Navy's interest is to assure this compound is not a constituent of concern at Mare Island. The intent is to sample in the Winter of 2017 and prepare a technical memorandum while working closely with regulatory agencies on plans additional assessment, if needed.

    Stay tuned, EnviroTech will provide an ongoing update of the progress being done by the Navy for this new emerging contaminant.

    Find Water Quality Instrumentation Here.

     

  • Low Flow Sampling In Ground Water

    Low Flow Sampling in Ground Water:
    An Overview on the Measurement of Water Quality Parameters to Determine Stability in Ground Water

    In December 1995, the United States Environmental Protection Agency developed and published a document entitled “Low-Flow Ground-Water Sampling Procedures” (EPA/540/S-95/54). Since then, the use of low flow sampling in ground water has increasingly been used to support site assessment and remedial performance monitoring objectives.

    The most common ground water purging and sampling methodology is to purge wells using bailers or high speed pumps to remove 3-5 casing volumes followed by sample collection. Adverse impacts can occur through this method affecting sample quality by increasing levels of turbidity. An overestimation of certain analytes – namely metals or hydrophobic organic compounds – may affect results with this method through the inclusion of otherwise immobile artifactual particles. Filtration of these turbid particles has proved undesirable in rectifying the turbidity problem and may, in fact, bias the results of contaminant concentration on the low side by potentially removing mobile (contaminant-associated) particles. These problems can often be mitigated by using low flow purging and sampling to reduce sampling-induced turbidity.

    In order to minimize the hydraulic stress placed on an aquifer during purging and sampling, the technique of using low flow sampling is recommended. This is typically done through the use of an adjustable rate pump to remove water from the screened zone at a rate that will cause minimal drawdown of the water level in the well. Drawdown is measured in the well concurrent with pumping using a water level meter. Low flow sampling does not require a specific flow rate or purge volume. Low flow refers to the velocity with which water enters the pump intake and that is imparted to the formation pore water in the immediate vicinity of the well screen. Water level drawdown provides the best indication of the stress imparted by a given flow rate for any given hydrological situation. Typical flow rates on the order of 0.1-0.5 L/min are used, but this does depend on site-specific hydrogeology. Low flow sampling relies on the ability to collect samples after water level and measured field parameters stabilize over three consecutive readings taken three to five minutes apart.

    Parameter Stabilization

    It is recommended that water quality parameters be used to determine purging needs prior to sample collection in each well. Stabilization of parameters such as pH, specific conductance, dissolved oxygen (DO), oxidation-reduction potential (ORP), temperature, and turbidity should be used to determine when formation water is accessed during purging. In general, the order of stabilization is pH, temperature, and specific conductance, followed by ORP, DO, and turbidity. Performance criteria for determination of stabilization should be based on water-level drawdown, pumping rate, and equipment specifications for measuring these parameters. Instruments such as the YSI 556 multiparameter instrument can simultaneously measure parameters while utilizing a flow cell to give continuous data.

    It should be noted that turbidity is a very conservative parameter in terms of stabilization. Turbidity is always the last parameter to stabilize and excessive purge times are invariably related to the establishment of too stringent turbidity stabilization criteria. It should also be noted that natural turbidity levels in ground water may exceed 10 nephelometric turbidity units (NTUs).

    In-line water quality indicator parameters should be continuously monitored during purging. Water level drawdown should also be checked periodically as a guide to flow rate adjustment with the goal being minimal drawdown (<0.1 m) during purging. Measurements of water quality parameters should be taken every three to five minutes if the above suggested rates are used. Stabilization is achieved after all parameters being measured have stabilized for three successive readings. In lieu of measuring all five parameters, a minimum subset would include pH, conductivity, and DO (or turbidity).

    Three successive readings should be within + 0.1 for pH, + 3% for conductivity, + 10 mv for ORP, and + 10% for DO or turbidity. These are guidelines provided for rough estimates. Many state agencies encourage the use of low flow sampling because it’s designed to collect a sample that most truly represents the water in the screened section of the aquifer surrounding the monitoring well. It does not come from water that is mixed within the well by a bailer or inertial sampler, nor does it come from an average of water that flowed the full length of a long screened interval.

    Conclusion

    The low flow sample can most often be trusted to best represent the contamination or lack thereof in the aquifer because it was produced by a process that minimizes stress on the aquifer or well. Low flow sampling also reduces the variability in sampling technique that is inherent in traditional bailing and purging procedures. In summary, low flow reduces the physical and chemical stresses, reduces the variability in sample procedures, increases the ability to determine well stabilization by continuously monitoring water quality parameters, and reduces the chance that changes in chemical concentrations are induced by the sampling technique.

    You can find more resources and technical field guides here

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