Subsurface installation

Comparisons of noise spectra from surface vaults and subsurface installations in mines (Fig. 9) or boreholes (Fig. 10) have repeatedly... 

To assess the well construction materials compatibility versus the subsurface environment and the pesticide of interest, manufacturers can provide data about the various well construction materials or samples can be acquired for laboratory analysis. Also, QC samples of each material can be collected during installation and preserved for laboratory analysis for potential sample bias, if necessary. In addition to well construction materials, the potable water used to clean drilling equipment and to prepare the grout and hydrate bentonite should also be collected for laboratory analysis (see Section 3.2.6). 

American Petroleum Institute (API), RP 14B. Recommended Practice for Design. Installation. Repair and Operation of Subsurface Safety Valve Systems. Third Edition, API, Washington, D.C., 1990. 

Construction of a subsurface structure that penetrates the water table only a short distance can be an effective LNAPL retention technique. Most underflow structures function in the same way as a surface baffle in an oil water separator or a septic tank. The structure must be carefully installed perpendicular to groundwater flow, and have some arrangement to collect the free-phase LNAPL. Often, a simple French drain (constructed parallel to the retaining wall) leading to a recovery well (with skimmer) is effective. A schematic diagram of a hydraulic underflow structure with a skimming unit is presented in Figure 7.3. 

Bioslurping uses a vacuum to extract NAPL and water from the subsurface soil (Figure 7.18). A small-diameter well is installed so that the well screen is open slightly above and below the water table. A smaller-diameter dip tube is inserted into the well and sealed against the outer well casing. The dip tube does not extend to the bottom of the well, but ends below the water table (or oil-water interface). The maximum depth of the bottom of the slurp tube is the suction-lift capacity of the vacuum pump. 

When the subsurface materials are uniform and isotropic (no gradational changes or confining layers) the airflow pathways are also uniform. The airflow paths developed for an open system and a covered system are shown in Figure 10.5. Selection of covered or uncovered is determined by the air paths necessary to contact the contamination. At some sites, inlet vent wells are installed to ensure air entry at specific locations. 

Subsurface Method. The subsurface method requires a high back-pressure foam maker and forces this foam through a pipe into the bottom of the tank. This pipe may be the existing product line or a line installed specifically for... 

To collect a sample, the probe with a SPME fiber installed is inserted into the soil. Air is pumped through the probe, drawing subsurface soil vapors into the probe tip and across the SPME fiber. Pumping air across the fiber increases uptake of target analytes by the SPME fiber relative to what is collected by molecular diffusion alone. Once a sample is collected, the SPME fiber is removed from the probe for analysis. To analyze the sample, the SPME fiber is inserted into a modified inlet system attached to the Fido sensor. The modified inlet serves to heat the SPME fiber, causing rapid and quantitative desorption of trapped molecules of analyte. The vapor-phase analyte is then swept into the sensor for analysis by a flow of carrier gas. 

CH2M Hill installed a complex irrigation and subsurface drainage system for highly saline metallurgic processing effluent at OREMET Titanium in Albany, Oregon. The cost of the study... 

EnviroWall is a barrier. It serves to isolate contaminants and must be combined with another technology to treat contaminants. According to the vendor, EnviroWaU barriers can be installed to a maximum depth of 50 ft. The presence of boulders in the subsurface will increase treatment costs. The long-term durability of the HDPE material is not known. The system is best suited to treat contaminated groundwater and leachate at depths up to 50 ft when the contaminated media is underlain by an aquitard or other impermeable layer. 

Table 1 shows the estimated installation costs of a funnel-and-gate system using the Envirowall barrier technology. The presence of boulders in the subsurface will increase installation costs (D18981F, p. 22). 

After hydrogeological, chemical, and biological analysis of the subsurface is complete and parameters are known, a network of plastic tubing is injected in the contaminated plume and microbes are injected to destroy the contaminants. An impermeable vertical barrier or lining is installed with a vibratory hammer and insertion plate to maintain hydrogeologic control. The technology is capable of reaching depths of up to 100 ft. 

The cost of GSE Curtain Wall technology varies depending on site conditions. The cost of the HOPE ranges from 10 to 30/ft (D18980E, p. 17). According to the U.S. DOE, the cost of a synthetic barrier installation depends on the subsurface composition, depth, and method of installation. The DOE estimates that installation costs range from 20 to 250/m (D17096R, p. 2). 

Grouting technologies have been commercially available for many years, however, new techniques are also being developed. In addition, there is considerable work being done to test the performance of alternative grouts in different subsurface environments using different installation techniques. 

In 1995, the vendor estimated that the waste treatment costs would range from 75 to 500/ft. Well/wellscreen length and subsurface lithology at a site signihcantly affect instaUation costs. This estimate may not include all indirect costs (D10159X, p. 8). Most horizontal wells are installed at private industry sites, so performance information and cost data are not commonly... 

At present, the well fluids from the four installed subsea wells flow through 4 in. 10-cm Coflexip seabed lines to the SALS mam told, then through a six-bore product swivel, and finally, through the mooring yoke to the receiving manifold on the FPSU. Well subsurface safely valves and wing valves are controlled hydraulically from a control panel on the FPSU deck by control lines routed through a 20-borc swivel on the SALS. 

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