Current Texas Drought Conditions

Texas is currently under drought conditions that may be more substantial than many people realize.  The Texas drought map (republished from the noted source) dated April 5, 2011, demonstrates large areas of Texas that are under severe, extreme, or exceptional drought conditions.  Water conservation requirements have already been triggered in some cities located in harder-hit areas.  We often take for granted the availability of good, clean water – but, our groundwater aquifers are not limitless.  We encourage everyone to get involved in water supply, water quality, and water protection issues.  Let’s be prepared for the future!

H₂A recently obtained closure from the Texas Commission on Environmental Quality (TCEQ) for a waste management unit located at an industrial plant in west Texas.  The unit, which consisted of a grey water pond used to collect discharge water from employee locker room sinks and showers, was regulated under the Resource Conservation and Recovery Act (RCRA) and administered by the TCEQ.  The initial site assessment of the grey water pond revealed detected concentrations of benzo(a)pyrene and total petroleum hydrocarbons in the soil that exceeded applicable action levels.  The soil in the affected area was excavated and subsequent confirmation sampling demonstrated attainment of site-specific Texas Risk Reduction Program critical residential protective concentration levels.

H₂A’s Shannon Walker, PE, and Si Xu, EIT, recently completed an engineering evaluation of the feasibility of converting an existing dual-phase extraction (DPE) system to two-phase extraction (TPE). The conversion would increase groundwater drawdown and applied vacuum, thereby improving groundwater capture. The evaluation involved determining necessary well flows and associated friction losses based on the existing pipe network. The blower types and sizes required to achieve the desired well flow and design vacuum were specified based on known system losses, losses to the formation, and vacuum versus flow relationships.

Prior to completing the engineering evaluation, H₂A personnel led field survey efforts to collect information about the existing pipe network including diameters, distances, fittings, and vertical elevation changes. This data, in conjunction with extensive site-specific DPE pilot test data previously developed by H₂A, formed the basis for the design calculations. System friction losses were estimated using the Darcy-Weisback equation. The equivalent length method was used to estimate the losses associated with various fittings (i.e., bends, reducers/enlargers, and valves) located throughout the system. Because fully turbulent flow was assumed, the Sacham equation was used to approximate a fully numerical solution for friction factor.

Note: Figure obtained from the U.S. Environmental Protection Agency’s Design Guidelines for Conventional Pump-and-Treat Systems published in 1997 (EPA/540/S-97/504).

H₂A recently expanded their staff, hiring Ms. Si Xu, an EIT and recent graduate of the University of Texas at Arlington (UTA). While pursuing her master’s degree in environmental engineering at UTA, Ms. Xu specialized in hazardous waste management and wastewater treatment.  Her post-graduate project involved an investigation into the relationship between biofilm build-up within the piping network of a water distribution system, and internal corrosion of the pipes. Ms. Xu also investigated the effect of using chloramine to prevent build-up of the biofilm. She completed her undergraduate studies in biology at the University of Central Oklahoma in Edmond, Oklahoma.  While at UTA, Ms. Xu served as treasurer of the student chapter of the Air and Waste Management Association. She is a native of China and speaks fluent Mandarin Chinese and Japanese.

The Aquifer Protection Interest Group is proud to present its first brown bag webinar of 2011
March 23, 2011, 1-1:30pm EST

Light Non-Aqueous Phase Liquid (LNAPL) transmissivity (Tn) can provide substantial improvements to LNAPL hydraulic mobility and recoverability analyses over traditional metrics such as LNAPL thickness in wells. Although methods to measure Tn have been available since the mid-1990’s, only within the last few years has widespread acceptance of Tn begun.  A nationwide team from industry, consulting, academia and government agencies has been working on an ASTM International® publication to provide guidance to measure Tn.  Four overall methods of Tn measurement are currently recognized:  1) baildown and slug tests, 2) manual skimming tests, 3) recovery data analysis, and 4) tracer testing.  Each of the four accepted methods varies with respect to its scale of measurement (time and space) and recommended utilization (startup/shutdown versus operational progress metric).  Tn should not be used as a risk-based site closure metric, but is a virtually ideal metric in maps, decline curve analyses, and other evaluations to measure LNAPL hydraulic recoverability.  To register please email rjones@ngwa.org with “LNAPL” in the subject line.

A Workshop on Advances in LNAPL Site Management will be held on Monday, March 14, 2011, as part of the AEHS Foundation’s Soil, Water, Energy, and Air Conference at the Mission Valley Marriott in San Diego, California.  Mark Adamski of BP is the Moderator for the Workshop, and a distinguished panel of experts will be addressing various topics during the Workshop.  Following their individual presentations, the Workshop will conclude with a panel discussion facilitated by Mike Hawthorne of H₂A Environmental, Ltd.  Click here to view the Conference Final Program.

H₂A recently presented an in-depth training webinar to the USEPA titled “An Exploration of LNAPL Transmissivity.”  H₂A’s Mike Hawthorne identified LNAPL transmissivity as an improved metric (versus LNAPL thickness or recovery data) with respect to LNAPL mobility, recoverability, and remediation operational progress.  Five techniques used to measure LNAPL transmissivity were reviewed in detail and the relative benefits of each method, including a discussion of temporal and spatial scale and measurement precision issues, were presented.  The strategic application of each method was identified and various uses for LNAPL transmissivity were presented including mobility/recoverability characterization, remediation design, and technical impracticability applications, among others.  (Click on graphic to view larger.)

H₂A’s Mike Hawthorne recently presented two, back to back, one-hour training webinars to the Missouri Department of Natural Resources. The first explored basic tenets of LNAPL science, including multiphase saturation distribution concepts and the benefits of multiphase extraction for both compositional change and saturation reduction in LNAPL remediation. The second webinar discussed LNAPL transmissivity as an improved metric for LNAPL mobility, recoverability, and operational progress during remediation.  (Click on graphic to view larger.)

H₂A recently utilized a trailer mounted, internal combustion engine (ICE), mobile dual-phase extraction (MDPE) system to successfully complete a 7-day, high vacuum remediation (HVR) soil vapor extraction (SVE) pilot test at a refined products pipeline release site, located in south central Oklahoma.  The area impacted is situated in a remote location within the pipeline right-of-way, where challenging terrain makes it inaccessible to larger and/or heavier equipment.  Our system has a small footprint (24 feet long by 8 feet wide) and weighs in at less than 6,000 pounds.  The on board treatment train consists of both vapor abatement and phase separation; the system is also equipped with an automatic data logger.  Using H₂A’s custom HVR equipment, our skilled field technicians were able to recover over 1,600 pounds of hydrocarbons from the subsurface during the pilot test.  H₂A currently owns and operates a fleet of four, custom HVR ICE MDPE systems.

At a former industrial facility located in North Texas, H₂A has achieved elimination of measurable (mobile) LNAPL in 15 of 16 monitoring wells (94%).  Dissolved BTEX plume reductions of 50-70% have also been noted after operating a custom-designed, multiphase extraction (MPE) remediation system at the site for only three years.  Therefore, both mass removal and compositional change remediation objectives have been realized utilizing MPE, a cost-effective technology compared to other techniques capable of achieving similar remedial endpoints.