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GROUND WATER MONITORING WORK PLAN •
<br /> DREDGE MATERIAL DISPOSAL SITE 1,ROBERTS ISLAND,PORT OF STOCKTON
<br /> acidification progresses, these cations tend to be removed from soil and
<br /> concentrated in ground water.
<br /> ■ Fe,Mn (EPA Method 6010)-These metals are ubiquitous in geologic media and their
<br /> solubility is strongly influenced by low pH. They are likely to be elevated in
<br /> acidic sediment waters. Their potential transport and accumulation on
<br /> foundation soils will be measured to directly assess attenuation.
<br /> ■ Cl, NOs(as nitrogen), SO4 (EPA Method 300.0)-These are the major species, in addition
<br /> to alkalinity, comprising the anions most common in ground water. Comparison
<br /> with the major cations will be used to establish the anion-cation balance and
<br /> verify that the major solutes have been measured and accounted. Sulfate and
<br /> nitrate are of particular interest because they are products acid generating
<br /> processes. In addition, the nitrate concentrations will be useful in subsequent
<br /> evaluation of nitrogen isotope ratios. The nitrate concentration will also be used
<br /> to identify samples suitable for a stable nitrogen isotope analysis.
<br /> ■ Ammonia (as nitrogen) and ammonium (EPA Method 350.3)-have already been
<br /> measured within in-situ river sediments. These nitrogen compounds are
<br /> included in the cation accounting and are a source of acidity and nitrate.
<br /> ■ Total Kjeldahl Nitrogen (TKN) (EPA Method 300.0)-measures the total nitrogen
<br /> content, including all forms of organic and inorganic nitrogen. The ratio of TOC
<br /> to TKN (ie., C to N ratio) is a useful indicator of whether or not the sediments
<br /> will release nitrogen that could migrate to underlying ground water.
<br /> ■ Total Al,As,Ba, Bo,Cu, Fe,Pb, Mn, Ni,Zn, organochlorine pesticides,polycyclic
<br /> aromatic hydrocarbons(EPA Methods 6010, 8081, 8270)-quantifies the total
<br /> concentrations of these chemicals in the dredged sediments for comparison with
<br /> the corresponding soluble concentrations.
<br /> ■ Waste Extraction using Distilled Water(DI-WET) for Al, As,Ba, Bo,Cu,Fe,Pb,Mn,
<br /> Ni,Zn, organochlorine pesticides,polycyclic aromatic hydrocarbons
<br /> (California WET with DI and EPA Methods 6010, 8081, 8270)- measures solutes
<br /> that can be extracted into water representative of a rainfall infiltration event. The
<br /> soluble fraction represents the potential concentration in water infiltrating
<br /> through the dredge materials that may be subject to attenuation in foundation
<br /> soils.
<br /> ■ Dissolved Al,As,Ba, Bo, Cu, Fe, Pb, Mn,Ni, Zn (EPA Method 6010)-quantifies the
<br /> dissolved concentration in water within the dredge materials, peat, and
<br /> underlying aquifer.
<br /> January 2005 Page 15 Environmental Risk Services,Corp.
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