Subsurface drainage systems

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... 

In addition to the classification of properties in Table I, the site can be characterized further as in Table II. Surface or subsurface drainage systems, if present, would be important additional descriptions. 

Drainage fabrics n. Fabrics used as filter media or separators in subsurface drainage systems. The fabric is installed around the drainage pipe, or coarse stone in the drain it allows water to pass freely from the soil to the drain, but prevents soil particles from migrating into the drain system. These fabrics are also used as outer coverings in prefabricated drainage composites and serve the same function as a filtering medium. 

A field drainage system draining the water away from the fill area. It can be divided into surface and subsurface drainage systems intended to increase the infiltration capacity and/or to control the excess surface runoff. 

MSEA (1998). Agricultural Drainage Water Quality Impacts and Subsurface Drainage Studies in the Midwest. Management Systems Evaluation Area. Ohio State University Extension. Bulletin 871, 40 pp. 

Surface waters can receive selenium from the atmosphere by dry and wet deposition, from adjoining waters that may contain selenium, from surface runoff, and from subsurface drainage. Sewage treatment plants are another source of selenium releases to water. Effluents from sewage treatment plants and oil refineries appear to be the major sources of selenium in the San Francisco estuarine system (Cutter 1989). In a study of direct discharges from oil refineries in San Francisco Bay, the average selenium concentration in the effluent was 0.067 mg/L with a range of 0.0066-0.156 mg/L (Barceloux 1999 ... 

Drainage Closed drainage work may include new closed drainage structures, culverts, and the cleaning and repair of existing systems. Subsurface utility exploration should be considered for closed drainage system modifications. ... 

The main drainage system must carry off the water to the discharge location(s) where it drains into natural open water. The system generally consists of shallow and/or deep collector drains that collect water of respectively the field surface drains or the field subsurface drains. Main drains transport the drainage water from the collector drains to the locations where the water is discharged into the river, sea or other open water. Outfalls (if required) are usually also considered to be part of the main drainage system. Shallow collector drains can be channels or ditches, while the deep collector drains include pipe drains and (deep) ditches. 

In addition to dilution of acid rock/mine drainage under oxidizing conditions, neutralization can occur under mildly or highly anaerobic conditions. This will create distinctive environments in which microorganisms thrive and nanoparticles form as a result of their activity. We describe two examples of such subsurface systems below. However, before turning to these topics, we note that Fe-based microbial ecosystems are not only found in association with metal sulfide deposits, but may be broadly relevant in the subsurface where Fe-rich minerals (biotite, olivine, pyroxenes, etc.) are present in reasonable abundance and dissolve, releasing aqueous ferrous iron. 

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