SITE INFORMATION AND CORRESPONDENCE

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Mr. Michael Campos, Esq. • _ 2 10 March 2004 the scientific proof that the LTU can meet this performance standard under specific design and operating parameters to be defined by Musco. If successfully demonstrated, the LTU's design and operating Parameters would become written conditions of future discharge, and soil and soil-pore liquid monitoring would be performed regularly thereafter to verify that the LTU continued to operate effectively. Constituents of concern would include all those with potential to exit the LTU and degrade groundwater as determined from the wastewater, additives to the LTU, and reaction products that could be reasonably expected to be in or derived from the wastewater and LTU additives. The Report does not adhere to basic design constraints imposed on an LTU. The treatment zone available for use in the demonstration — and for operation thereafter—cannot exceed a vadose zone of five feet below ground surface. The Report proposes use of the entire soil profile. Shallow groundwater cannot be used as a component of the treatment system (i.e., for dilution or further attenuation of waste constituents). The Report proposes use of groundwater for both. Storage of waste constituents in the treatment zone as the Report proposes is unacceptable—unless the LTU design provides positive control that immobilizes the waste constituents and LTU operation provides for periodic and timely removal of the waste constituents from the LTU to a Title 27 site or for eventual closure of the LTU as a Title 27 site. The Report does not provide for positive control and does not address waste removal. The Report must describe specifically the design parameters and the sound science that Musco will employ to demonstrate all that is required by Provision G.2.f. The purpose of a demonstration is to yield hard data documenting the effectiveness of the LTU in the degradation, transformation, and immobilization of all constituents of concern by means of soil and soil-pore liquid samples. The Report proposes to construct hypothetical models. The demonstration must account for all constituents added to the LTU along with the wastewater constituents and reaction products. The Report proposes to evaluate just select waste constituents. Even if the Report's methodology for evaluating the assimilative capacity of the LTU treatment zone was acceptable, the premise of the design is flawed. Groundwater monitoring data submitted to date indicate use of the entire vadose zone has not been effective in attenuating organic constituents, as groundwater occasionally contains detectable concentrations of decomposable waste constituents (BOD and TKN). Musco also recently applied acid to LTU soils to improve soil permeability. While not treating LTU soils with acid adversely impacts the health of the plants, their consumption of other waste constituents, and their yield, the acid adds constituents to the system and mobilizes inorganic waste constituents (e.g., sodium) to facilitate their leaching from the treatment zone, both of which are counterproductive. Natural features of the site and processes create their own challenges. The steep slopes in some areas and tight soils in most areas necessitate low application rates that concentrate waste constituents before they even enter the LTU. Plant extraction of water inadvertently concentrates remaining constituents in the soil- pore liquid and leachate. The acceptability of the LTU is predicated on the predictability of the quality of leachate that exits relative to quality of groundwater and quality limited by water quality objectives. For all the above reasons, the Report as submitted is not adequate and an extension of the Provision G.2.f submittal deadline to perform the work outlined in the Report is not warranted. We are sufficiently confident of the nominal character of groundwater to conclude that expensive and prolonged studies to improve the quantification of background constituent concentrations will yield diminishing returns. This nominal character of groundwater is much better than both effluent character and current effluent limitations. Musco is faced with the difficult challenge of designing a land