Observations of particle movement in a monitoring well using the colloidal borescope

Evaluation of the Colloidal Borescope as a Monitoring Tool at the Waste Isolation Pilot Plant Site

“…These values give mean pore-water velocities ranging from 0.2 to 150 pm/s (0.02 to 13 m/day). Thus, the velocities shown by the colloidal borescope are consistent with pore-water velocities estimated independently within the factor of four uncertainty proposed by Kearl (1997).…”

“…This is because flow fields are often distorted in the immediate vicinity of wells so that more water passes through the well than passes through an equivalent cross section of aquifer (Drost et al, 1968). Kearl (1997) estimates that water velocity through a well may be as much as four times greater than the seepage velocity (the average velocity per cross-sectional area) in the surrounding formation.…”

“…Kearl (1997) states that compression of flow lines leading toward a well may cause velocities to increase by as much as a factor of four, so the actual velocities at H-1 9 may range from only 13 to 73 pm/s (1.1 to 6.3 m/day). [n a medium in which flow enters and exits a well under Iaminar conditions only through fractures, the flow velocity through the well should be related to the flow velocity in the fractures in the surrounding formation, increased by the compression factor discussed above.…”

Intercomparison of Groundwater Flow Monitoring Technologies at Site OU 1, Former Fort Ord, California

“…This methodology will provide useful approximations in many instances, but it ultimately depends on the assumption that the available conductivity data accurately reflect the conditions throughout the target site. Moreover, hydraulic conductivity is generally determined by pumping or slug tests, that may undesirably average zones of preferential flow that are the main conduits of contaminant flow (Kearl and Case 1992;Kearl 1997), or generate problematic wastes in aquifers known or suspected to be contaminated. Sensors that do not depend on conductivity data can potentially provide useful flux data for modeling or remediation optimization without the drawbacks of traditional techniques, and provide a useful link between laboratory and field observations.…”

Estimation of water velocities in boreholes using a new passive flowmeter

“…The colloidal borescope is capable of measuring flow up to 3 cm s -1 at selected depths within a well and thus has the ability to measure flow from individual fractures. Based on the work presented by Kearl (1997), colloidal borescope measurements in the field should be reduced by a factor of 1 to 4 to calculate seepage velocity in the adjacent aquifer. However, several problems may arise when this device (User Guide 2013, p. 20-30) is used.…”