In:
Groundwater, Wiley, Vol. 40, No. 1 ( 2002-01), p. 25-36
Abstract:
The potential of direct‐push technology for hydraulic characterization of saturated flow systems was investigated at a field site with a considerable degree of subsurface control. Direct‐push installations were emplaced by attaching short lengths of screen (shielded and unshielded) to the bottom end of a tool string that was then advanced into the unconsolidated sediments. A series of constant‐rate pumping tests were performed in a coarse sand and gravel aquifer using direct‐push tool strings as observation wells. Very good agreement (within 4%) was found between hydraulic conductivity (K) estimates from direct‐push installations and those from conventional wells. A program of slug tests was performed in direct‐push installations using small‐diameter adaptations of solid‐slug and pneumatic methods. In a sandy silt interval of moderate hydraulic conductivity, K values from tests in a shielded screen tool were in excellent agreement (within 2%) with those from tests in a nearby well. In the coarse sand and gravel aquifer, K values were within 12% of those from multilevel slug tests at a nearby well. However, in the more permeable portions of the aquifer (K 〉 70 m/day), the smaller‐diameter direct‐push rods (0.016 m inner diameter [I.D.]) attenuated test responses, leading to an underprediction of K. In those conditions, use of larger‐diameter rods (e.g., 0.038 m I.D.) is necessary to obtain K values representative of the formation. This investigation demonstrates that much valuable information can be obtained from hydraulic tests in direct‐push installations. As with any type of hydraulic test, K estimates are critically dependent on use of appropriate emplacement and development procedures. In particular, driving an unshielded screen through a heterogeneous sequence will often lead to a buildup of low‐K material that can be difficult to remove with standard development procedures.
Type of Medium:
Online Resource
ISSN:
0017-467X
,
1745-6584
DOI:
10.1111/gwat.2002.40.issue-1
DOI:
10.1111/j.1745-6584.2002.tb02488.x
Language:
English
Publisher:
Wiley
Publication Date:
2002
detail.hit.zdb_id:
2066386-9
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