H

Grizzly™ Grinder pump by F.E. Myers Co. ground cover Plants grown to keep soil from eroding. groundwater Subsurface water found in porous rock strata and soil. groundwater infiltration (GWI) The seepage of groundwater into shafts and

tunnels. groundwater recharge The replenishment of a groundwater source, often by

injection of tertiary treated wastewater. grout Fluid, or semi-fluid, cement slurry for pouring into joints of brickwork or

masonry. GRP Glassfiber reinforced plastic. grubbing The process of removing tree stumps or roots. GTO Gas turbine oxidizer. Guardian™ Strainer product line by Tate Andale, Inc. guide vane A device used to direct or guide the flow of a liquid or vapor. guinea worm disease See “dracunculiasis.” gunbarrel A vertical settling tank used to separate free oil from water in the

production of crude oil. Gundline® Containment liner by Gundle Lining Systems, Inc. Gundnet Drainage net by Gundle Lining Systems, Inc. Gundseal Geocomposite liner by Gundle Lining Systems, Inc. Gutling Former name of USFilter/Gutling. GW Groundwater. GWDR Ground Water Disinfection Rule. GWI Groundwater infiltration. GWM Groundwater monitoring. GWUI Groundwater under the direct influence of surface water. gypsum The mineral consisting primarily of fully hydrated calcium sulfate. Chem-

ical formula is CaSO4-2H20. Gyrazur™ Softening clarifier by Infilco Degremont, Inc.