Horizontal Wells Demonstrated at U.S. DOE's Savannah River Site and Sandia National Laboratory

Site Name:

Savannah River Site and Sandia National Laboratory

Location:

Aiken, SC, and Albuquerque, NM

Period of
Operation:

1988 - 1993

Cleanup
Type:

Field demonstration

Technology:
Soil Vapor Extraction (report focuses on installation of horizontal wells above and below water table)
- Four different systems were used for directional drilling and horizontal well installation
- A short radius petroleum industry technology was used to install wells at 65 ft bgs and 150-175 ft bgs; these wells were constructed of steel
- A modified petroleum industry technology was used to install two comparable wells; these wells were constructed of HDPE
- A mini-rig utility industry/compactional tool drilling technology was used to install a well at 35-40 ft bgs; this well was constructed of fiberglass
- A mini-rig utility industry technology was used to install two wells at 100 ft bgs; these wells were constructed of PVC

Cleanup Authority:
Not identified

Technical Contacts:
Dawn Kaback
Colorado Center for Environmental Management
(303) 297-0180 ext. 111
E-mail: dsdaback@csn.net
Management Contacts:
Skip Chamberlain
DOE EM50
(301) 903-7248
E-mail: grover.chamberlain@em.doe.gov

James A. Wright
DOE SRS
(803) 725-5608
E-mail: wrightjamesb@srs.gov

Contaminants:
Chlorinated solvents

Waste Source:
Multiple sources, including leaks of solvents

Type/Quantity of Media Treated:
Groundwater (in situ)
- geology consists of 200 ft of alternating units of permeable sands with low fines; water table is 120 ft bgs

Purpose/Significance of Application:
Demonstrate use of horizontal wells to treat groundwater at multiple sites and locations

Regulatory Requirements/Cleanup Goals:
- Test the feasibility of installing horizontal wells in unconsolidated sediments using directional drilling technology

Results:
- Directional drilling technology was used to install a total of seven wells (steel, stainless steel, PVC, HDPE, and fiberglass) to depths of 35 - 175 ft bgs, with horizontal screen sections ranging from 150 - 400 ft
- The wells were used to demonstrate in situ air stripping, in situ bioremediation, and thermally enhanced soil vapor extraction; four of the wells were later integrated in a vapor extraction remediation system

Cost Factors:
- Costs for horizontal wells vary widely based on drilling method and size of rig, type of drilling tool, drilling fluid, guidance system, vertical depth, total well length, site geology, well materials, and number of personnel on site
- Costs for installing a PVC or HDPE well using a small to medium sized utility-type drilling rig are projected as $164/m ($50/ft)
- Estimated capital costs for horizontal wells were comparable to the capital cost of five vertical wells; O&M costs for the one horizontal well were less than one-third of the O&M costs for five vertical wells

Description:
This report describes the installation and use of horizontal wells at several DOE sites, including Savannah River Site (SRS) and Sandia National Laboratories. At SRS, seven wells were installed at depths of 35 175 ft bgs, with horizontal screen sections ranging from 150 400 ft, and using the following materials: steel, stainless steel, PVC, HDPE, and fiberglass. The wells were used to demonstrate in situ air stripping, in situ bioremediation, and thermally enhanced soil vapor extraction; four of the wells were later integrated in a vapor extraction correction action. The SRS demonstration identified two important factors for consideration during design of horizontal wells: (1) trips in and out of the well bore should be minimized; and (2) well materials should be adequately flexible to negotiate curves.

At Sandia, several pieces of commercial machinery were tested and evaluated, including the water-assisted Jet Trac Boring System, the air-assisted True Trac Boring System, the P-80 rod pusher, and the Pierce Arrow pneumatic hammer tool. Based on the results from initial testing of these machines, construction was begun on a prototype machine, the X-810.