Site-specific influencing factors

Costs of steel or concrete towers can vary with a number of factors hence, market conditions, contractor s experience, equipment availability, design details, and site-specific influences will likely determine whether steel or concrete is the most economic material. 

Sustainable Agriculture. The third factor that will influence the future of pesticide sales is the emphasis on sustainable agriculture systems that rely on more natural pest control methods and reduced pesticide usage. These are integrated systems that requke nutrients and crop protection chemicals from on-farm natural sources and cultural methods. Many current sustainable farms are site-specific systems that may depend on the soils in a... 

Before the selection of a specific treatment technology can be made, an understanding of the site-specific factors which drive the selection of that technology is required because these factors can influence the evaluation of the advantages and limitations of competing technologies. The information required to resolve these site-specific issues falls into four categories waste composition and matrices, waste quantity, treatment objectives, and the reactions involved in the treatment of the contaminated material. 

Many of the factors that influence the c.xtcnt of contamination are site specific, cither climatic or hydrogeological. Other factors that influence the extent of contamintition relate to land surface features such as topography or dcNclopmcnt, which determine exposure routes. Additional important... 

All risk assessment techniques, whether qualitative or quantitative, require an estimate of frequency of event occurrence. This frequency, which is extremely site specific, can be influenced by many factors. 

Nickel is strongly adsorbed by soil, although to a lesser degree than lead, copper, and zinc (Rai and Zachara 1984). There are many adsorbing species in soil, and many factors affect the extent to which nickel is adsorbed, so the adsorption of nickel by soil is site specific. Soil properties such as texture, bulk density, pH, organic matter, the type and amount of clay minerals, and certain hydroxides influence the retention and release of metals by soil (Richter and Theis 1980). 

Although many of the costs for chemical oxidation technologies will be site specific, chemical costs will generally average 15 to 30% of the total remediation costs. Factors that influence chemical costs will include the chemical oxygen demand (COD) of the contaminated media, pH, the size of the site, and initial contaminant concentrations (D22442A, pp. 19, D-1). 

Many site-specific factors can infiuence the cost of VESTRIP treatment. Soil properties that can influence the cost of any SVE system include permeability, porosity, depth and stratigraphy of the contamination, site heterogeneity, and seasonal water table fiuctuations. In general, the more permeable and homogenous the soil, the more efficiently any SVE will operate, and the lower treatment costs will be (D22449H, p. 4-4). 

Establishing the frequency (i.e., is toxicity consistent or transient between sample), degree (i.e., magnitude) and persistency (i.e., how toxicity changes over time) of toxicity will be important, since these factors can provide insight into the type of substance responsible for toxicity, and can also influence subsequent TRE activities. The actual number of samples required to assess these factors will be site-specific and depend predominantly on effluent variability. 

Just as the models used to predict the transport and fate of chemicals in the environment are sensitive to numerous site-specific parameters such as average rainfall and soil types, the equations used to determine exposures for particular activity patterns are sensitive to demographic parameters. These include general population characteristics (e.g. age distributions), culturally-influenced factors (e.g. rates of fish and vegetable consumption), and location-specific factors (e.g. workplace exposure patterns are generally different from those in the home). EPA has recently published the results of its efforts to determine values for numerous parameters that are characteristic of the average population of the U.S. (4), but the risk assessor must adjust these parameters to fit the specific population she or he is evaluating. 

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