Bruce Manchon, P.G.
Janeil Environmental Solutions
Bruce Manchon is a California, Nebraska and Texas Professional Geologist with over 35 years of professional experience in the environmental and petroleum industries. He received a B.A. in geology from the University of Colorado and is currently a senior hydrogeologist and owner of Janeil Environmental Solutions in Boulder, Colorado. Currently, he is responsible for oversight of the technical aspects within the project scope relating to geology and hydrogeology, remediation and ensuring that the technical objectives of the scope of work are met for a variety of commercial clients.
Bruce has direct experience with DNAPL and LNAPL contaminated soil and ground water projects in many varied hydrogeological settings, including sand and clay terrains as well as karst (epikarst), and hard rock and fractured rock environments. Scope of experience includes field investigation, extensive hydrostratigraphic analysis to define the effects of hydrogeology on contaminant fate and transport, and contaminant recovery for vadose and saturated zone remediation programs.
Recently, he implemented a remedying for chlorinated solvents utilizing enhanced reductive dichlorination. Additionally, he successfully designed and remediated a TPH impacted UST excavation with RegenOx.
Bruce is part of a team in Nebraska, that is evaluating well workovers for improvement of groundwater quality.
SESSION CHAIR & PLATFORM PRESENTER - Getting Through Rehab: Injection/Extraction Wells
Well Workovers – New Direction for Improvement of Groundwater Quality
This presentation is based on the key finding that was identified in the Nebraska Grout Study, that properly sealed wells will prevent the preferential pathway in the annulus of a well. We will discuss closing the preferential pathway found in existing wells and more importantly how to prevent them from occurring in newly constructed wells.
The importance of isolating the primary producing aquifer cannot be stated strongly enough. An effective seal above and below the aquifer needs to be established. Neat cement sealing the annulus above the SWL for well workover while a chip bentonite should be used in new well construction for sealing the annulus above/below the SWL.
This should be combined with a competent surface seal. Without a good seal, water quality may be impacted due to changes of the geochemistry of the aquifer from the mixing of waters from different units; the mixing of surface water and groundwater; and, the introduction of oxygen during the cycling of the irrigation season.
The importance of understanding the complete hydrostratigraphy, e.g. do you know if your well penetrates through a perched layer, is often overlooked when siting new wells. We will present an example identifying the impact of a perched layer on groundwater beneath it.
The key question to ask - what do we do with the 1,000,000+ wells around the country not properly constructed? The answer is either workover or abandonment - one well at a time. A case study will be presented showing the impact of a workover and the improvement of water quality. Well construction, borehole geophysics, geochemistry, and historical data were evaluated and incorporated into the design of the well workover. The objective was accomplished, by installing a sufficient volume of grout material without destroying the well which provided a competent seal and appropriate groundwater protection.
Bruce Manchon, P.G., Bo Bonn, and Bill Christopherson – GeoSpec Drilling, LLC; and John Sciacca, P.G. – AECOM