Us Epa Dover Chemical Superfund Site Proposed Plan (With Attachments)
US EPA RECORDS CENTER REGION 5 478885 Dover Chemical Superfund Site Proposed Plan Dover, Ohio June 2015 This P r o p o s e d Plan provides a description of the Dover Chemical Corporation Site ("Site"), identifies t h e Preferred Remedial Alternative ("Preferred Alternative") for the off-site g r o u n d w a t e r plume, and provides the rationale for this preference. In addition, the Proposed Plan includes summaries of other cleanup alternatives evaluated to address the off-site g r o u n d w a t e r plume associated with the Site. The alternatives discussed in this Proposed Plan relate only to the off-site groundwater c o n t a m i n a t i o n associated w i t h the Site. As part of an Administrative Order by Consent issued in O c t o b e r 2000, Dover Chemical is addressing the contaminated groundwater on-site via a p u m p and treat system. This system captures contaminated groundwater on-site so that it does not migrate off-site, and treats the c o n t a m i n a t e d water via air stripping before discharging to a nearby surface water body under an NPDES permit. Dover Chemical has also installed soil vapor extraction systems at t w o locations on-site to address contaminant source areas. These systems reduce contaminant mass within ongoing sources in the vadose z o n e . These on-site activities are reducing contaminant mass in the subsurface, and minimizing g r o u n d w a t e r contaminant migration off-site. The on-site activities are explained later in this document. This d o c u m e n t is issued by the United States Environmental Protection Agency (EPA), the lead agency for Site activities, and the Ohio Environmental Protection Agency (OEPA), the support agency. Following issuance of this Proposed Plan, and after considering any and all public c o m m e n t s received during t h e 30 day public c o m m e n t period, EPA, in consultation w i t h OEPA, will select a final remedy for the off-site g r o u n d w a t e r plume. This final remedy will be presented in a document called a Record of Decision (ROD). EPA, in consultation w i t h O E P A , may m o d i f y the Preferred Alternative or select another response action proposed in this Plan based on n e w information or public c o m m e n t s . Therefore, t h e public is encouraged to review and c o m m e n t on all of the alternatives presented in this Proposed Plan. EPA is issuing this Proposed Plan in accordance w i t h Section 117 of t h e Comprehensive Environmental Response, Compensation and Liability Act of 1980 (CERCLA), as a m e n d e d by the Superfund A m e n d m e n t s and Reauthorization Act 1986 (SARA), which requires the issuance of decision documents for remedial actions taken pursuant to Sections 1 0 4 , 1 0 6 , 1 2 0 , and 122. The P r o p o s e d Plan is also part of EPA's public participation responsibilities under 40 CFR 300.430(f)(2) of the National Oil and Hazardous Substances Pollution Contingency Plan (NCP). This P r o p o s e d Plan summarizes information that can be found in greater detail in the Remedial 1
Investigation/ Feasibility Study (RI/FS) report, the Feasibility Study A d d e n d u m II (FSA- II), and other d o c u m e n t s contained in the Administrative Record file for the Site. EPA and the State encourage the public to review these d o c u m e n t s to gain a m o r e comprehensive understanding of the Site and the extensive Superfund activities that have been conducted at the Site to date. I. SITE HISTORY The Dover Chemical Corporation Site (Site) is an operating chemical manufacturing plant located in Dover, O h i d . The facility currently produces, alkyl phenols, chlorinated paraffin and organophosphites. The chlorinated paraffin are used for metal working lubricants, flame retardants, and plasticizers for vinyl products; and the organophosphites are additives used in the polyolefin, rubber and vinyl industries. The first facilities at the site were constructed before W o r l d W a r II, and the plant has continuously manufactured chemicals f r o m the 1940's t o the present. The Site is approximately 60 acres in size and consists of a main plant area east of Interstate 77 (1-77) along w i t h an abandoned canal/lagoon area, and a w o o d e d low lying area west of 1-77. Land use surrounding the facility is varied and includes industrial, commercial and residential areas. Industrial facilities are located t o the north and south. Several blocks of residences are located east of the Site and extend to the north and south. Figure 1 presents a site map. Operations at the plant have resulted in releases of organic c o m p o u n d s t o the ground surface and ultimately to the groundwater at the Site. The c o m p o u n d s released on-site included chlorobenzenes; carbon tetrachloride (CCI4); polychlorinated dibenzodioxins and polychlorinated dibenzofurans ([PCDDs/PCDFs], a group of c o m p o u n d s referred t o collectively as "dioxins"); and other chemicals. Activities that caused the releases of c o m p o u n d s t o the environment include disposal of still bottoms f r o m a chlorobenzene distillation process in a low lying area in the southwest part of the plant area known as Area H; temporary storage of hexachlorocyclohexane (commonly known as benzene hexachloride or BHC) near building 21 in the area known as A r e a G, in the center of the plant; and various spills, tank and piping leaks, and other unintentional discharges during the 1950s, 1960s, and 1970s. Raw materials f r o m the phenol process used to manufacture chlorobenzenes are believed to have contained dioxins that were concentrated in the still bottoms deposited in A r e a H (see Figure 2). II. Clean-up and Investigative activities to date Since 1981, multiple environmental investigations have b e e n conducted at the Site to assess the impact of contamination to the environment. These investigations identified high concentrations of hazardous substances in soil on-site and in groundwater both on-site and offsite. Substances identified on-site include: CCL4, c h l o r o f o r m , m o n o c h l o r o b e n z e n e (MCB), 1,22
dichlorobenzene (1,2-DCB), 1,3- dichlorobenzene (1,3-DCB), 1,4-dichlorobenzene (1,4-DCB), 1,2,4-trichlorobenzene, dioxins, hexachlorobenzene (HCB), and trichioroethene (TCE). Off-Site g r o u n d w a t e r sampling at the time found that similar chlorobenzene c o m p o u n d s had migrated off-site and created an off-site groundwater plume of contamination. On O c t o b e r 2 3 , 1 9 8 1 , EPA issued a 3007 and 3013 Resource Conservation and Recovery A c t o r d e r to Dover Chemical Corporation (Dover) to study and address soil and groundwater c o n t a m i n a t i o n at the Site. After completing t h e study, Dover r e m o v e d approximately 6,800 3 cubic yards (yd ) of contaminated soil and waste f r o m the site. In 1982, organic c o m p o u n d s w e r e detected in a w a t e r supply well located on the Dover plant property. As a result of this finding, Dover initiated additional investigations in 1983, to better define the nature and extent of soil and groundwater contamination associated w i t h the Site. B e t w e e n 1983 and 1986, Dover conducted several additional voluntary investigations at t h e Site. As part of these investigations, Dover installed groundwater monitoring wells around the Site. The investigations revealed additional locations of g r o u n d w a t e r and soil c o n t a m i n a t i o n . These investigations also indicated that contaminated groundwater had migrated s o u t h w a r d beyond the boundary of the plant property. In 1986, Dover submitted a draft Feasibility Study to EPA and OEPA. After review of this d o c u m e n t , the EPA d e t e r m i n e d that additional investigation w o u l d be required to determine the nature and extent of t h e contamination associated w i t h releases at the property. Based o n information gathered from all the years of investigative w o r k c o n d u c t e d at this Site, four areas of concern w e r e identified. These areas are identified as follows: Plant area soils Lagoon and canal area soils Plant area groundwater Off-site groundwater plume Dover entered into a three party Administrative Order by Consent (AOC) with EPA and OEPA on August 2 4 , 1 9 8 8 . Under this Order, Dover agreed to complete a Remedial Investigation a n d Feasibility Study (RI/FS). During the Rl investigation conducted under t h e 1988 order, additional chemicals of concern [dioxins and BHC] w e r e discovered in soils on-site. The scope of t h e 1988 Rl investigation was e x p a n d e d to include the characterization of t h e environmental media at the site for these additional constituents. Based on the concentrations of the additional chemicals f o u n d , the EPA requested that Dover conduct an interim removal action on-site to reduce the mobility and potential for contact with plant area soils containing dioxins. On July 12, 1991, Dover and EPA entered into an Administrative Order of Consent to conduct interim soil cleanup on-site and at adjacent off-site 3
roadways used by Dover Chemical truck traffic. The Interim soil cleanup was taken to mitigate direct human exposure and included the following: Excavation and removal of off-site soils above the EPA residential area soil cleanup standards for dioxin (1 part per billion (ppb)) and securing on site soils; Capping active plant areas; Securing inactive areas w i t h contaminant levels above the soil cleanup standards by installing snow fencing t o prevent access; Fencing the entire plant area to maintain security a n d prevent unauthorized access; Reducing the average dioxin soil concentration on t h e A r m o r y property adjacent to the Site to b e l o w the soil clean up standard by removing the soil in area M and adding 6 inches of clean fill and paving to area A C ; and Removing soil above the soil cleanup standard for dioxin and installation of a parking lot and top soil to the east of Building 31 (Area P and part of A r e a K). The A r m o r y property and Areas M , A C , P, and K are depicted in Figure 2. The interim action was c o m p l e t e d in late 1994. In 1993, EPA proposed the Site to the National Priorities List (NPL). The Site has not been finalized on the list. In 1994, Dover submitted an expanded RI/FS. EPA did not approve the risk assessment portion of the 1994 RI/FS and conducted an independent risk assessment to evaluate risks at the Site. In August 1999, after reviewing information in the submitted 1994 RI/FS, the 1995 baseline risk assessment, the previous removal activities c o m p l e t e d at the Site and current site conditions, EPA made a determination that a non-time critical removal action w o u l d be appropriate to address the plant area soils, lagoon and canal area soils, and the plant area g r o u n d w a t e r to prevent and mitigate further releases of hazardous substances to the environment. On October 20, 2000, Dover and EPA entered into an Administrative Order on Consent to conduct a n o n time critical removal actions in the on-site areas identified at Dover. The off-site g r o u n d w a t e r plume that has spread south of the facility was evaluated consistent with the 1988 RI/FS A O C . Soil removal w o r k in the plant area, lagoon area and canal area was c o m p l e t e d by Dover in recent years t o address dioxin contaminated soils as well as other source areas identified as part of the 2000 A O C . Some of the major areas excavated on-site are identified on Figure 3. As work continued to address the on-site environmental issues via the 2000 non-time critical removal action, Dover expanded the groundwater monitoring network and collected additional data to evaluate the nature and extent of the groundwater plume that extended south of the 4
facility (off-site g r o u n d w a t e r plume) in order to have enough information to determine h o w to address it properly. Il.a. OFF-SITE GROUNDWATER MONITORING B e t w e e n 2000 and 2008, Dover Chemical w o r k e d w i t h EPA and O E P A to better define the offsite g r o u n d w a t e r plume. Additional groundwater monitoring wells were installed and a long t e r m g r o u n d w a t e r monitoring plan to collect g r o u n d w a t e r samples quarterly was i m p l e m e n t e d . The g r o u n d w a t e r investigations identified three primary zones within the aquifer. Those zones are identified as follows: M o n i t o r i n g well zone Screening location b e l o w the designation w a t e r table A-Zone 0-9 feet B-Zone 35-50 feet C-Zone 80-90 feet Early investigations identified contamination migrating off-site below A-zone. Off-site B-zone wells were f o u n d to have contaminants associated with on-site contamination above drinking water standards. G r o u n d w a t e r in the C-zone was below clean-up standards set for on-site contamination. Dover has conducted quarterly groundwater monitoring since 2005. Based on the risk associated w i t h contaminants in the off-site B-zone groundwater plume, nine contaminants of concern (COC) w e r e identified. Concentrations of these contaminants have shown a general decrease over time. Recent m a x i m u m concentrations of each contaminant (detected during quarterly sampling in 2013 and 2014) for each contaminant are s h o w n in the following t a b l e : Off-Site G r o u n d w a t e r - M a x i m u m Recent Contaminant Concentrations (B-Zone) S e p t e m b e r 2013 - June 2014 Maximum Concentration Off-Site Wells Well# M C L (ug/l) Benzene 0.36J MW-25B 5 monochlorobenzene 360 MW23B 100 Chloroform 0.28 MW25B 100 1,2, dichlorobenzene 1700 MW31B 600 1,3 dichlorobenzene 300 MW31B N/A 1,4 dichlorobenzene 1400 MW31B 75 1,2,4 trichlorobenzene 8.7 MW39B 70 1,1 dichloroethane 6.1 M W 35B 7 5
trichioroethene MW31B 16 5 J estimated value li b. 2013 FEASIBLITY STUDY - ADDENDUM II Dover c o m p l e t e d several FS studies as part of the investigative w o r k conducted since 1981. In 1996, an FS w a s c o m p l e t e d as part of the 1983 AOC. The off-site g r o u n d w a t e r portion of this FS was not a p p r o v e d and EPA requested that an a d d e n d u m be c o m p l e t e d to look at ways to address this c o n t a m i n a t i o n . In 2 0 0 1 , Dover submitted an FS A d d e n d u m for the off-site groundwater p l u m e , w h i c h required additional work. Dover prepared an FSA w o r k plan to gather additional data to fully evaluate m o n i t o r e d natural attenuation as viable g r o u n d w a t e r cleanup option and prepared a second Feasibility Study A d d e n d u m (referred to as the 2013 FSA-II). Dover installed an extensive network of piezometers w h i c h demonstrated an inward groundwater f l o w gradient t o w a r d the facility. The existing g r o u n d w a t e r p u m p i n g scheme, which operates as part of the 2000 NTCRA AOC, effectively prevents c o n t a m i n a t e d groundwater f r o m leaving the site. The 2013 FSA-II provided t h e following information about the off-site p l u m e : the conceptual m o d e l ; the stability of the aquifer such that the plume is not changing over t i m e ; three dimensional delineation of the p l u m e ; the geochemical conditions; and microbial population and c o m p o u n d specific isotopes t o evaluate w h e t h e r the in-situ microbial population is appropriate to biodegrade the plume contaminants. The work indicates that (1) the off-site groundwater p l u m e is stable in size and is not expanding; (2) the g r o u n d w a t e r p u m p i n g system has maintained capture of contaminated groundwater on-site and c o n t a m i n a t e d groundwater is no longer migrating off-site; (3) geochemical conditions within t h e off-site groundwater plume indicate that natural attenuation including biological processes is naturally occurring in the aquifer; and (4) modification of the geochemical conditions in the off-site plume could accelerate these biological processes and help reduce contaminant concentrations within the plume. Figure 4 shows the estimated boundaries of the B-zone off-site g r o u n d w a t e r plume where total chlorobenzenes exceed 100 ug/l, as of M a r c h 2014. This is the plume that will be addressed by this action. 6
Il.c. ON-SITE ACTIVE REMEDIATION Soil Vapor Extraction (SVE) To address contaminant sources located in t h e plant area on-site, Dover implemented a Soil V a p o r Extraction (SVE) systems in A r e a G beginning in 2005. Nearly 50,000 pounds of V O C s have been removed f r o m the subsurface to date. In 2014, Dover Chemical added a second SVE system in Area H to accelerate groundwater cleanup in the plant area (see Figure 2). SVE may be expanded to other areas of the plant in t h e future. Groundwater Pump and Treat System Dover has used groundwater for non-contact cooling water since the beginning of plant operations. Additional production wells w e r e installed in 1988 (PW-5) and 1992 (PW-6) to increase plant cooling w a t e r capacity and t o keep groundwater contamination f r o m moving offsite. Pumping wells P W - 7 and P W - 8 w e r e installed in December 2000, and P W - 9 was installed in 2004, to minimize mobilization of dioxins and to further reduce the potential for contaminants to migrate off-site through groundwater. Figure 2 identifies the locations of the current pumping wells. Extracted groundwater is treated by air stripping to remove V O C s before discharge to Sugar Creek under a National Pollution Discharge Elimination System (NPDES) permit. Dioxins are relatively insoluble, and are believed to have migrated to t h e aquifer beneath the Dover facility in organic liquids. Subsequent dissolution of those liquids is believed to have left t h e dioxins in the aquifer as small particulates that may be mobilized by groundwater p u m p i n g . W i t h the discovery of dioxins in groundwater on-site, the p u m p i n g system was reassessed to help determine an optimal pumping scenario for the p r o d u c t i o n / r e m e d i a t i o n wells so that Dover could continue to recover VOCs w i t h o u t causing migration of dioxins. After a failed a t t e m p t in 2005-2007 to optimize the pumping scheme to achieve this goal, Dover is currently evaluating a revised s c h e m e (pumping scenario 2013A). III. COMMUNITY INVOLVEMENT ACTIVITIES TO DATE Various public meetings and availability sessions were held in the Dover, Ohio area w h e n the various investigation activities, interim actions, and removal actions w e r e being c o n d u c t e d . EPA has a Site information repository at the Dover Public Library in Dover, Ohio. EPA also maintains a Site w e b page located at h t t p : / / w w w . e p a . g o v / R 5 S u p e r / n p l / o h i o / O H D 0 0 4 2 1 0 5 6 3 . h t m l . The w e b page and information repository are regularly updated with current Site information. The public is encouraged to visit t h e website and information repository for information regarding Superfund work at the Site. 7
IV. SITE CHARACTERISTICS The Site is located in Tuscarawas County in east central Ohio. The facility is located off of Interstate 77, and consists of four parcels of land encompassing approximately 60 acres near the City of Dover city limits. The City of Dover, Ohio has a population of approximately 13,000. Land use a r o u n d the Site is varied and includes industrial, commercial, and residential areas. The Site is located on a meander plain of Sugar Creek that overlies a buried valley filled with glaciofluvial sediments comprised primarily of sand and gravel. The buried valley varies b e t w e e n 0.5 and 2 miles wide and is up to 290 feet deep. In the vicinity of the off-site g r o u n d w a t e r plume, the buried valley is greater than 200 feet deep. The upper foot of soil is predominantly fine grained that transitions to coarse sand and gravel b e l o w 10 feet. The permeable o u t w a s h deposits result in a relatively homogenous and isotropic aquifer. These deposits are underlain by inter-bedded layers of marine sandstone, shale, limestone, and coal. Locally these consolidated sedimentary strata appear to be horizontal. Monitored Natural Attenuation Analysis of Off-Site Groundwater Plume M o n i t o r e d Natural Attenuation ( M N A ) is the reliance on natural attenuation processes to achieve site specific remedial objectives within a timeframe that is reasonable c o m p a r e d to other remedial actions being considered to address site contamination. The natural processes that are at w o r k in this approach under favorable conditions include a variety of physical, chemical or biological processes such as diffusion, dispersion, adsorption, and degradation, that act without h u m a n intervention to reduce the mass, toxicity mobility v o l u m e or concentrations of contaminants in soil or groundwater. Natural attenuation processes typically occur at all sites, but to varying degrees of effectiveness depending on the types and concentrations of contaminants present and the physical, chemical and biological characteristics of the groundwater. The off-site groundwater plume has been defined in three dimensions by t h e existing monitoring well and piezometer network. Data has been collected to support the consideration of natural attenuation including trend analysis, geochemical data, c o m p o u n d specific isotope analysis, and molecular biological assessment w i t h and without in-situ a m e n d m e n t s . Table 1 is a summary of well identification numbers, locations in relationship to the off-site plume (i.e. upgradient, bounding, plume, sentinel), roles of the well (i.e. transect, centerline), sampling dates, and field and laboratory analysis methods for monitoring wells screened in the B-zone of the aquifer. G r o u n d w a t e r elevation data has been collected at the off-site g r o u n d w a t e r plume quarterly since 2005. A complete set of g r o u n d w a t e r elevation data was collected in June 2012 f r o m all locations, b o t h on-site and off-site, to gain an accurate picture of groundwater f l o w within the on-site and off-site B-zone plume. Figure 5 presents contour map of the B-Zone groundwater 8
potentiometric surface (35-50 feet below the w ater table) using a 0.5 foot contour intervals for t h e off- site plume. The g r o u n d w a t e r flow regime is well established and well u n d e r s t o o d . Trend Analysis Chlorinated benzene c o m p o u n d s are the p r e d o m i n a n t contaminants in the off-site g r o u n d w a t e r plume. The heart of the off-site plume is downgradient of the natural f l o w field f r o m a known source area on-site identified as the f o r m e r fractionation t o w e r area (see Figure 2). Although on-site g r o u n d w a t e r is captured by the pumping of non-contact cooling water, it is likely that desorption f r o m soils in the saturated zone off-site continues to contribute chlorinated benzenes t o off-site g r o u n d w a t e r a n d on-site g r o u n d w a t e r near the extreme s o u t h e r n boundary of the site at M W - 3 9 B . Since M a r c h 2 0 0 5 , Dover Chemical has collected quarterly g r o u n d w a t e r monitoring data. In general, contaminant concentrations of M C B , 1,2-DCB, and 1,4-DCB have decreased over t i m e a n d w i t h distance f r o m the Site. In M a y 2013 DCBs and M C B concentration plume maps w e r e p r e p a r e d using data collected from the B-Zone of the aquifer f r o m M a r c h 2005 and M a r c h 2012 t o illustrate concentrations of M C B and DCBs both on-site and w i t h i n the off-site p l u m e . Figure 6 of this proposed plan, was prepared using the same data set only using concentrations for t o t a l chlorobenzenes (both M C B and DCBs) in the off-site plume, to help illustrate this point. Both sets of plume maps s h o w that the overall contaminant concentrations have decreased and t h e area encompassed by the offsite plume has shrunk betw een 2005 and 2012. T r e n d analysis of total DCB and M C B concentrations for quarterly events f r o m 2005 to 2012, using data points along the center line of the off-site g r o u n d w a t e r plume at M W - 3 9 B (0.1 mile f r o m the Site), M W - 2 5 B (0.3 mile f r o m the Site), M W - 3 1 B (0.5 miles f r o m the Site) and M W - 3 8 B (0.9 miles from the Site) are presented in Figures 7 and 8. T h e trend analysis for DCB concentrations illustrated in Figure 7 indicates that DCB concentrations decreased .over time at M W - 3 9 B (near the southern boundary of the Site) and M W - 2 5 B (0.3 miles downgradient from the Site), increased at M W - 3 1 B (0.5 miles downgradient f r o m the Site), and w e r e not detected at downgradient sentinel well location M W - 3 8 B (0.9 miles downgradient f r o m t h e Site). The trend analysis for M C B concentrations illustrated in Figure 8 indicates that M C B concentrations w e r e below the M C L at M W - 3 9 B and trending slightly down f r o m 2005 to 2012. At M W - 2 5 B , M C B concentrations t r e n d e d d o w n t o w a r d levels below t h e MCL. At M W - 3 1 B , M C B concentrations were highly variable with no apparent t r e n d and w e r e generally above the MCL. A t sentinel well M W - 3 8 B , M C B concentrations t r e n d e d up slightly, but concentrations remained below the M C L . This apparent increase in M C B downgradient may reflect degradation of DCBs to an M C B intermediate. Figure 9 presents M C B and total DCB concentrations and trend lines f r o m M a r c h 2005 through M a r c h 2012 for three wells within the most contaminated part of the offsite plume: M W - 2 5 B , M W - 3 1 B , and M W - 3 7 B . The figure illustrates concentration trends over time, and shows that 9
M C B and DCB concentrations in wells M W 25B and M W 37B have decreased o v e r t i m e since 2005. At M W - 3 1 B , M C B concentrations decreased by about 3 5 % and DCB concentrations decreased by about 4 5 % f r o m 2005 to 2012. At M W - 3 7 B , M C B concentrations decreased by about 35%, and DCB concentrations decreased by about 65% f r o m 2005 to 2012. M C B and DCB concentrations in well M W - 3 1 B vary irregularly and do not s h o w a clear trend over the time period considered. M C B concentrations wells M W - 3 1 B and M W - 3 7 B have trended to b e l o w the M C L f r o m 2005 to 2012. The total mass of the plume was analyzed using the same data set used for evaluation of the feasibility study. The results of this analysis are presented in the FSA-II. In broad terms, the analysis s h o w s that DCB mass decreases over time and M C B mass increases over time, supporting the conclusion that natural attenuation processes are reducing the DCB concentrations and producing M C B along the centerline of the off-site plume. Geochemical conditions A site specific study was c o m p l e t e d for the Site to determine if natural attenuation is ongoing in the off-site groundwater plume and w h e t h e r e n h a n c e m e n t through the manipulation of g r o u n d w a t e r biogeochemistry w o u l d be beneficial. Seventeen monitoring wells located within the off-site groundwater plume w e r e identified for analysis during 4 quarters of sampling (June 2011, S e p t e m b e r 2011, D e c e m b e r 2011 and M a r c h 2012). The following sections of this proposed plan summarize the geochemical testing c o n d u c t e d . Dissolved Oxygen (DO) - DO was monitored to assess the current level of oxygen in the B-zone horizon of the aquifer where contamination has been found. DO data are essential for understanding the type of bacteria that may be active in the aquifer and how biodegradation of VOCs of interest could potentially be enhanced. DO levels in the off-site plume indicate that anaerobic conditions prevail in the B-Zone g r o u n d w a t e r within the area of the off-site plume. However, previously collected DO data indicate that strongly aerobic conditions (DO concentrations 10 mg/L) prevail both upgradient f r o m the Site and in the A-Zone directly above the off-site plume, strongly suggesting that the natural geochemical conditions of the aquifer are aerobic. Anaerobic conditions within the plume may be caused by the presence of c o n t a m i n a n t s ; the naturally occurring oxygen in the groundwater may be nearly completely c o n s u m e d by microorganisms as they metabolize contaminants. pH - pH w a s monitored to determine relative groundwater acidity that may inhibit biological c o m m u n i t y health and for evidence of pH depression due to formation of carbon dioxide, generated as a byproduct during biodegradation of chlorine organic contaminants. Microbial activity generally requires a pH range of 6 to 8. G r o u n d w a t e r pH levels were primarily b e t w e e n 7 and 8. Eh - Eh w a s monitored to gather information regarding redox conditions, which indicate w h e t h e r t h e B-Zone horizon of the aquifer at a particular well location is a reducing or oxidizing 10
e n v i r o n m e n t . Understanding existing redox conditions is essential in evaluating how to manipulate the subsurface to facilitate in-situ biological contaminant destruction. Results indicate a mild to moderately reduced g r o u n d w a t e r capable of supporting reductive dechlorination of chlorinated VOCs. Carbon Dioxide (CO2), Chloride - CO2 and chloride w e r e m o n i t o r e d for evidence of natural degradation of chlorinated organics in the groundwater. The presence of elevated chloride in conjunction with elevated CO2 can in s o m e instances provide a line of evidence of natural degradation of chlorinated organic g r o u n d w a t e r contaminants. Carbon dioxide is f o r m e d during the metabolic processes of many biodegradation reactions and is also used as an electron acceptor during the process of methanogensis. Results of these indicators suggest intrinsic biodegradation is occurring in the heart of the
finding, Dover initiated additional investigations in 1983, to better define the nature and extent of soil and groundwater contamination associated with the Site. Between 1983 and 1986, Dover conducted several additional voluntary investigations at the Site. As part of these investigations, Dover installed groundwater monitoring wells around the
Rapid Flow, Titration, Turbidimetry, Ultraviolet- Visible Spectroscopy (UV/VIS) Parameter/Analyte Water pH EPA 150.1 Turbidity EPA 180.1 Calcium EPA 200.7 Iron EPA 200.7 Magnesium EPA 200.7 Potassium EPA 200.7 Silica, Total EPA 200.7 Sodium EPA 200.7 Aluminum EPA 200.8 Antimony EPA 200.8 Arsenic EPA 200.8 .
EPA Test Method 1: EPA Test Method 2 EPA Test Method 3A. EPA Test Method 4 . Method 3A Oxygen & Carbon Dioxide . EPA Test Method 3A. Method 6C SO. 2. EPA Test Method 6C . Method 7E NOx . EPA Test Method 7E. Method 10 CO . EPA Test Method 10 . Method 25A Hydrocarbons (THC) EPA Test Method 25A. Method 30B Mercury (sorbent trap) EPA Test Method .
This Request for Proposal (RFP) is being issued by The Downtown Dover Partnership, a non-profit 501(c)(6) in the City of Dover, Delaware. The Downtown Dover Partnership (DDP), working in concert with the City of Dover and multiple public and non-profit agencies, is seeking an experienced, dynamic, and diverse professional
The Downtown Dover Parking Study is an initiative of the City of Dover and the Dover / Kent County Metropolitan Planning Organization (DKCMPO), in partnership with the Downtown Dover Partnership (DDP). These partners retained our consulting team, led by Langan Engineering and Environmental Services, Inc.
FALCON REFINERY EPA Publication Date: 7/10/2015 1 FALCON REFINERY SUPERFUND SITE San Patricio County, Texas EPA ID# TXD086278058 Site ID: 0602349 EPA Region 6 State Congressional District: 27 Contact: Brian Mueller 214.665.7167 Updated: July 2015 Current Status
vii References The following resources were used in producing this manual: EPA: Package Treatment Plants MO-12, EPA 430/9-77-005, April 1977 EPA: Summary Report: The Causes and Control of Activated Sludge Bulking and Foaming, EPA 625/8-87/012, July 1987 EPA: Manual: Nitrogen Control, EPA 625/R-93/010, September 1993 EPA: Handbook: Retrofitting POTWs, EPA 625/6-89/020, July 1989
EPA Method 7E –NO, NO 2, NOx Yes EPA Method 8 –SO 2, SO 3 Yes EPA Method 10 –CO Yes EPA Method 11 –H 2 S ( 50 ppm Yes EPA Method 16 –TRS Yes, including mercaptans and other reduced sulphurs EPA Method 18 –VOC’s Yes EPA Method 26 –HCl, HF Yes EPA CTM 027 –NH 3 Yes. ADVANTAGES OF FTIR
Nazism and the Rise of Hitler 49 In the spring of 1945, a little eleven-year-old German boy called Helmuth was lying in bed when he overheard his parents discussing something in serious tones. His father, a prominent physician, deliberated with his wife whether the time had come to kill the entire family, or if he should commit suicide alone. His father spoke about his fear of revenge, saying .
