WORK PLANS - Laserfiche WebLink

Home Browse Search

SECTION 1 Introduction and Background This work plan describes an interim remedial action and well destruction activities that will be performed at the Koppel Stockton Terminal in Stockton,California (also called the site). 1 .1 Site Background The Koppel Stockton Terminal is a former dry fertilizer warehouse and bagging facility with associated infrastructure (for example, railroads).The site is located west of Ventura Avenue, between the extensions of Hazelton Avenue and Sonora Street, in the City of Stockton.The site is approximately 1 mile west-southwest of the Interstate 5/Highway 4 interchange, next to the Port of Stockton.The layout of the Koppel Stockton Terminal is shown on Figure 1(figures are presented at the end of this work plan). The site has been the subject of numerous investigations since the early 1990s to identify the extent of nitrogen contamination in the soil and grmundwrater. Onsite soil borings revealed the presence of discontinuous beds of alluvial sand,gravel,clay,and silt deposes(CH2M HILL,2000a). It is possible that a portion of the site or the entire site has been covered with fill, The water table is approximately 3 to 10 feet below the ground surface (bgs) (0 to-7 feet mean sea level).TAr droarrdwater flow direction is generally to the south-southeast, but can vary across the site, likely in responrso b rw##A wearby pumping,tidal fluctuations, and recharge of ponded runoff (CH2M HILL, 2000a). A test grove of 267 poplar tree+ www*too"on approximately 1 acre of the southern portion of the site in May 1998 to evaluate the effwiftwom of tewt trees in removing nitrogen from soil and groundwater, a process known as phytoremediation. Ar ndd1W%w0 1.150 hybrid poplar trees and 230 willow trees were planted near the turnaround area,stormwater o.wrt ttrwrwr tyging plant, and the area north of the warehouse from March through June 2000 (CH2M HRU #XW,, Iwo s rating locations are shown on Figure 1.The remedial action was implemented in accordance www+ ow Ar"wd o Action Plan (RAP) (CH2M HILL, 2000a) and subsequent conditional approval of the RAP from the Ryan orator Quality Control Board,Central Valley Region (Water Board) (Water Board, 2000). Approximately 740 poplar treat awv*Mmowrd in 2002 because the trees died or showed signs of heavy infestation by the western popes ritarvwwW moth (moth) (CH2M HILL, 2003).The moth is a wood-boring insect and a pest of birch, poplar,and w.Yirw croft w southern California and the Central Valley.The selected contingency action to address trvv ross was replanting with tree species resistant to the moth and, in doing so,establishing a mature but diverse groves of trees to prevent future large-scale losses from a pest or disease. Replanting with resistant tree species, wsAudng Paulownia (Paulownia fortunei),sycamore maple(Acer pseudoplatanus),sycamore(Plrnorars ocenfaloo),fruitless mulberry(Morus alba), black locust(Robinia pseudoacacia),sour gum (Nysso syhWko), and water gum (Tristanio lavrina) has been ongoing since 2003. As described in the RAP,soil sampW was planned at 5-year intervals to monitor soil nitrogen overtime and evaluate the effectiveness of phytoremediation.The first 5-year sampling event was conducted in July 2006, and results were documented in the Five-year Evaluation and 2006Annual Groundwater Monitoring Report (CH2M HILL,2006).The second 5-year sampling event was conducted in July 2011,and results were documented in the Ten-year Evaluation and 2011 Annual Groundwater Monitoring Report(2011 Annual Report;CH2M HILL, 2011).The results showed a reduction in nitrogen concentrations in both soil and groundwater across most of the site, indicating that the selected remedy, phytoremediation,is effective.The exception is the former bagging plant area, which is discussed in Section 1.2 and is the focus of this interim remedial action work plan. RDD/131490001 (C 5152.DOC%) I-1 ES052913233837