Potential contaminants at a dredged spoil placement site, Charles City County, Virginia, as revealed by sequential extraction

Table VI Concentrations of trace elements (mg/L) in groundwaters from the monitoring wells after the placement of the dredged sediments at the replacement site

Trace element	USEPA MCLs^a for drinking-water	Baseline analyses^b	SDS2^c			SDS3^c			SW30^c			SW31^c
			4/20/02^d	10/19/02	10/26/03	4/20/02^d	10/19/02	10/26/03	4/20/02^d	10/19/02	10/26/03	4/20/02^d	10/19/02	10/26/03
Ag	0.1	bdl	bdl	bdl	bdl	bdl	bdl	bdl	bdl	bdl	bdl	bdl	bdl	bdl
Cd	0.005	bdl	bdl	bdl	bdl	bdl	bdl	bdl	bdl	bdl	0.00065	bdl	0.00058	bdl
Sb	0.006	bdl	0.054	bdl	bdl	bdl	bdl	bdl	0.0055	bdl	bdl	0.0071	bdl	bdl
Tl	0.002	bdl	bdl	bdl	bdl	bdl	bdl	bdl	bdl	bdl	bdl	bdl	bdl	bdl
Pb	0.015	bdl	0.048	bdl	bdl	bdl	bdl	bdl	bdl	bdl	bdl	bdl	0.012	0.0052
Cr	0.1	bdl-0.004	0.03	0.0048	0.0035	0.04	0.0098	0.0035	bdl	bdl	bdl	0.015	0.036	0.018
Fe	0.3	2.1–8.1	50	6.3	1.4	5.7	1.7	5	bdl	bdl	bdl	8.7	37	15
Ni	0.1	bdl-0.009	0.028	0.0096	0.0058	0.03	0.012	bdl	bdl	bdl	bdl	0.013	0.026	0.014
Cu	1.3	bdl	0.039	bdl	bdl	0.0064	bdl	bdl	bdl	bdl	bdl	0.0051	0.019	0.0077
Zn	5.0	bdl-0.16	0.088	0.56	0.03	0.16	0.2	0.03	bdl	0.03	0.03	0.062	0.120	0.049
As	0.01	bdl	0.0079	bdl	bdl	bdl	bdl	bdl	bdl	bdl	bdl	bdl	bdl	bdl
NO₃ + NO₂	11.0+1.0	bdl-0.11	1.1	0.15	bdl	1	2.8	0.55	bdl	bdl	0.18	7.5	4.5	10
Total sulfide	...	bdl	2	bdl	bdl	1.7	bdl	bdl	bdl	bdl	bdl	bdl	bdl	bdl
SO₄	250.0	7–76	...	43	33	...	44	26	...	29	55	...	39	43
TOC	...	1.0–3.1	9.4	3.8	1.8	3.7	3.8	3.7	2.1	2.8	3.4	<1.0	1.7	1.0

^aUSEPA maximum contaminant levels for drinking water are based on the data provided by Fetter (Ref. 11), except for new As MCL.
^bBaseline analyses are the concentration ranges for trace elements in a set of local groundwaters collected prior to placement of the dredged sediments at the replacement site.
^cSamples Analyzed by Gascoyne Laboratories, Inc.
^dThe collection date of the groundwater samples.

ISSN: 1467-4866