API Publication 4671:1998 pdf download

API Publication 4671:1998 pdf download.TECHNICAL BULLETIN ON OXYGEN RELEASING MATERIALS FOR IN SIitu GROUNDWATER REMEDIATION.
The potential disadvantage of this method is that existing monitoring wells may not be placed optimally for plume treatment (e.g., well spacings may be too large to provide adequate spatial coverage of the plume) or wells may have too small a diameter or screen length to hold a sufficient volume of ORM to be effective. Additional disadvantages are that unsupported socks may distort upon hardening, making them difficult to remove (Koenigsberg, 1997) and that some regulatory agencies may not allow the conversion of “treatment wells” that once contained ORM socks to be used in the future as monitoring wells.
For use in direct-push boreholes, which typically have a smaller diameter than permanent wells, ORM powder is mixed with water (typically one part water to two parts ORM) to form a liquid sluny, which is injected into the aquifer at high pressure using a grout pump. In one method, the drive-point is first placed at the greatest depth and then the ORM slurry is injected from the tip of a drive-point tool string as it is slowly withdrawn from the soil (Figure 3-Ib). The shape of the ORM-treated zone is typically irregular and depends on a number of factors including slurry viscosity and density (a function of the water: ORM powder mix ratio); injection pressure; and the strength, hydraulic conductivity, and pore size distribution of aquifer sediments, which typically vary both vertically within a borehole and laterally from one borehole to the next. The relatively lower cost of direct-push boreholes (compared to the cost of constructing wells or augered boreho)es) can allow smaller borehole spacings and thus more intensive ORM treatment, but the injected ORM can only be replenished by additional injections.
When site conditions are not suitable for direct-push boreholes (e.g., high strength or rocky sediments or excessive depths to the contaminated zone), ORM powders and/or slurries can be used to backfill augered boreholes, e.g., through the center of a hollow-stem auger. Depending on the borehole diameter, this method may allow the addition of larger quantities of ORM than either wells or direct-push boreholes, but the OR.M is generally not retrievable and can only be replenished by constructing additional borings. In direct-push and angered boreholes the injected slurry may eventually harden into an ORM “concrete,” which may reduce the 02 release rate. Ln addition, the reduced hydraulic conductivity of the ORM slurry-injected sediment may reduce the groundwater velocity through the ORM treated zone and thus the mixing of contaminated groundwater with the released 02. Additional field work is needed to understand the distribution and behavior of injected ORM slurries.