Data Gaps And Limitations Environmental Sciences Essay

An extensive site history and description of the Trimpell Middleton petrochemical site has been put forward and documented in the phase I site investigations carried out for Environmental Agency and documented in the Atkins scoping study.

This historic site is situated to the North and West of Middleton and positioned on National Grid with reference SD420590 (Semple, 2013 as cited in Atkins, 2000). It is about 2km south-east of Heysham and occupies an expanse of 116 hectare. The site was built and managed as a joint project between Trinidad Lake Asphalt, Imperial Chemical Industries (ICI) and Shell to produce aviation fuel during the World War II after which it was closed down in 1945 (CSM). It became operational again in 1948 under the ownership of Shell and ICI with a reform in its production techniques and with the introduction of new chemicals (CSM). The main refinery operations and chemical productions closed down in the 1970s and the site became derelict and has been decommissioned. The only finger prints observable in the site is the operations of SRM limited formerly Solrec Limited who are in to solvent refinery and recovery (CSM).

The site is considered in two basic areas for the purpose of this report. These are the Main Refinery Area (MRA) and Final Production Tank Farm (FPTF). The main refinery area includes all the land initially occupied by the refinery, located to the west of Middleton Road and an extension which is assumed not to have been occupied by the refinery. The Northern part of the site was purchased by Solrec Limited in1975 while the Lancaster City Council has the ownership of the central and south-western parts (CSM).

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The Final Production Tank Farm (FPTF) is situated between the railway passageway to the east and Middleton road to the west and contains four giant tanks buried within the vicinity of supporting buildings and parts of the undeveloped land. At present, the Lancaster City Council is the known owner of the two storage tanks in the northern most part while the two other storage tanks and the remaining part of the FPTF in the furthermost south towards the railway passageway are thought to be owned by Middleton Business Park Ltd (CSM).

SITE GEOLOGY

The site has its central part lying flat with a rising land to the east in the direction of Middleton Road and Trimpell Tip and to the west near Whittam Hill. The site is elevated in both the northern and southern parts compared to the central part which is low-lying with the furthermost southern part of the site having a lower topography than the central part (CSM). Over these years, the site topography and ground elevation has changed because of dumping activities including inert waste materials in some parts of the site (CSM). This is documented in the report and was also observed during the site reconnaissance visit.

PRODUCTION ACTIVITIES:

In the operational years of the refinery, gasoline was stored in tanks at the banks of Heysham and was conveyed to the tanks on Whittam Hill for refinery use. The conveyance relied on gravity and supported by the topography (CSM).

The refinery operation stopped after the World War II and restarted in 1948 with the refinement of crude to produce gas oil, fuel oil, gasoline and butane (CSM). Sulphur was removed from the crude at the Hower Baker Plant possibly by conversion to hydrogen sulphide and absorbed into an alkaline solution in the caustic soda plant (CSM). Knowledge of recovery of sulphur or the sulphide is lacking.

The catalytic cracking process introduced sour water condensate which was likely to contain hydrogen sulphide, ammonia, phenol and some other hydrocarbons. Knowledge of the fate of the sour water produced is lacking. Mercaptan, an intermediate product would possibly have been removed by the use of sulphuric acid or sodium hydroxide during production of gasoline in a process of sweetening. This could be by conversion of mercaptan to disulphide (CSM).

Ammonia was produced in the main refinery site in the ammonia stalls. Possible by-products of this process are coal tars and ammonia. Hydrogen used in ammonia production was produced in a water gas plant. The residues of this process were carbon dioxide and carbon monoxide which were removed by brushing with caustic soda and injection with copper liquor respectively. Methanol was produced and was stored in ICI product tanks thought to have been previously used to store petroleum. This manufacturing technique stopped and methane was produced by the addition of high temperature steam to waste oil obtained from Shell production activities.

ICI went in to manufacturing of insulating board after the war using isocyante process and asbestos was thought to have been used in the process. Insulation board production was continued by Kingspan Insulation and Coolag Limited after ICI left. Knowledge of their manufacturing details is lacking.

Also within the vicinity of the site is Trimpell Tip where waste from the refinery and nitrates processing such as incinerator residues, domestic and commercial waste, potentially combustible substances and inert materials were disposed.

HIGHLIGHTS OF PHASE I

The process of contaminated land management as described in contaminated land report 11 (CLR II) falls within three paradigms. These are risk assessment, option appraisal and implementation of the remediation strategy. The phase I investigation aims to define the purpose of the investigation, identify arrears of concern and to refine a preliminary conceptual site model using available information (CLR II). This is achieved by collating and evaluating desktop information, site reconnaissance survey and possibly interview from people who have historical or current information of the site. In doing this, all the information gathered would be needed to construct a conceptual site model that takes in to cognizance all contaminant sources, pathways and receptors or potential receptors.

The report documented in phase I investigation (CSM) has identified areas of concern which is a major objective of the initial environmental site assessment. This includes the refinery area and the final production tank farm. The report makes known the historical sequence of events that have taken place in the site from agricultural use which preceded the refinery to its current derelict state. The report also describes the site’s environmental setting including the topography and geology.

DATA GAPS AND LIMITATIONS

The report from the scoping study of the phase I investigation provides basic information about the site including site history and description, geology and a range of production activities that took place at the site. However, there are uncertainties and incompleteness on knowledge of certain historic activities and operations that took place at the site. The most pronounced limitation in the site scoping study is the lack of knowledge of the precise locations where certain operational activities were carried and knowledge of the extent of pollution impacted on the site by reason of those activities. Report shows that some locations of historic facilities (structures) have been identified while some are yet to be traced. Example is the underground tanks whose locations are yet to be determined. Knowledge of some underground utilities is lacking such as piping and sewer system and consequently their pollution or contaminant linkage is not ascertained. Other notable information includes:

The historic processing and manufacturing areas have been identified but there are missing information in the phase I report regarding the disposal and fate of most of the chemicals used in the manufacturing and processing operations.

The areas of concern have been identified but contaminant releases and migration mechanisms are yet to be determined.

The site geology such as topographical features is known but knowledge of its hydrology, hydrogeology, drainage routes, direction of ground water flow is not known.

Contaminants of concern have been identified but whether release has occurred at the areas of concern is yet to be identified.

Information is lacking on the background concentrations of the site as this would be a parameter to consider during remediation processes.

Because of the gap and limitations in information from the phase I report, the need arises to propose and develop a phase II site investigation and conceptual model which would be used to fill the missing gaps or information.

OBJECTIVES OF PHASE II

The purpose of phase II investigation is to pull together enough information to determine if release has occurred at each area of concern identified or not (CDEP, 2010). A release is established to have occurred if concentrations of contaminants of concern detected exceed the limits stated in the reasonable confidence protocol (CDEP, 2010). In this stage, consideration will be given to both environmental setting and potential receptors. The site scoping study shows a possible presence of a wide array of contaminants generated from refinery or petrochemical operations, fertilizer works, railway haulage and asbestos manufacturing related process. The potential receptors of concern for these contaminants are humans, fauna, flora, controlled waters and ecological receptors. From the phase I study, a number of significant pollution linkages have been identified with most of them being probable and possible pollution linkages. A complete pathway exists between contaminant sources and the site drainage (CSM). This pathway is complete through discharge of site surface water run-off to the Morecambe Bay which is the ecological receptor.

The phase I report recognizes a probable significant pollutant linkage through volatile emission, dust generation, direct contact to infrastructure, fauna and human health. Also, likely to exist is a significant linkage in which ground water or surface water could reach deeper groundwater in the aquifer.

For the final production tank farm no significant pollution linkage was identified. Noteworthy that the tanks were sealed off during decommissioning and such suggests no significant linkage. However, a probable pollutant linkage has been demonstrated to exist between shallow groundwater and the site drainage system (CSM). There is probable existence of a pathway from groundwater and contaminated soil through dust generation, volatile emission and direct contact to infrastructure, fauna and human health.

Table 1: List of possible contaminants to be found on the site

Contaminants

Class of chemical

Fuel oil

Organic

Gasoline

Organic

Butane gas

Organic

Phenol

Organic

PAHs

Organic

Coal tars

Organic

Naphtha

Organic

Waste oil

Organic

Alcohols

Organic

Esters

Organic

Ketones

Organic

Toluene

Organic

Xylene

Organic

Hexane

Organic

Cellulose thinner

Organic

Chlorinated Solvents

Organic

Sulphur

Inorganic

Caustic Soda

Inorganic

Ammonia

Inorganic

Mercaptans

Inorganic

Copper Liquor

Inorganic

Sulphuric acid

Inorganic

Nitrates

Inorganic

Asbestos

Inert materials

Table 2

CONCEPTUAL SITE MODEL AND PHASE II INVESTIGATION

Identified Potential Areas of Concern (Potential Sources)

Potential Release Mechanism (Potential Migration Pathway)

Expected Release Locations Suitable for Sampling and Analysis for Phase II Investigation.

Underground storage tanks

Tank leaks, over fills, Piping, valve, and dispenser leaks.

I) For probable tank leaks, the underlying soil at the edge of the tank and sidewall can be sampled.

II) For over fills, sample collection should be underneath the tank or vent pipes at the low lying or by the sloping area.

II) For piping and valves, sampling should be along the pipes, pipe joints, and the vicinity of the valves.

Underground water

Leaching, from the vadose zone through the fringe capillary in to the underground aquifer.

Sampling wells should be bore at the lowest lying area of the site, from the site geology; the central and southern parts are the lowest lying areas, so sampling should be carried out within that area. Permanent or temporary wells could be installed. A temporary well enables the detection of contaminant release while permanent well enables to monitor the ground water flow and the effects of season and tides on the fate of contaminants.

Trimpell Tip

Leaks, degradation and leaching.

Within, beneath, down slope within the vicinity of the tip.

Delivery and Loading areas

Spills and leaks

Cracks on the asphalt or motor way reinforcement. If there are no basement where cracks could be found, then areas with sparse vegetation which are observable within the vicinity of concern.

Fire service water dam

It could be a reservoir or sink for an array of contaminants which seep into it. It can leach downwards or the degradation products may persist and can also be remobilized into the surrounding environment.

Beneath, adjacent to the dam.

Legacy structure (building) which are fingerprints of the remaining in the site.

Spills, volatile emission and depositions.

Cracks on walls and floors, joints between the building roofing, wall and floors.

Main refinery’s drainage system

Migration, leaching to underground water.

Underground water or soil core.

Solrec Limited

Release from solvent recovery and refinery plant. Spills and leaks.

Soil within the vicinity of plant, water sample from the low lying terrain of the site

Gasoline storage tanks on Whittam Hill.

Leaks, spills from over fills

Adjacent and underlying soil.

SAMPLING STRATEGY

The limitations and gaps of the phase I study suggest the need for more site interrogation through sampling to ascertain the presence of contaminants at the areas of concern. The sampling approach to be used will be more direct based on the information that has been obtained from phase I on the particular areas of concern. In addition, the data quality objective is very important in designing a sampling protocol needed to achieve site specific objectives.

Ground water

The identification of a probable pollutant linkage for ground water or surface water seepage into deeper groundwater necessitates a sampling protocol for groundwater. Besides, ground water sampling is an integrated sample which is representative of more spatial zone. This is because of effect of several environmental system including the unsaturated soil, capillary fringe and aquifer constituents on the underground water (USEPA, 1995).

Table 3: Proposed sampling locations, number of soil samples and permanent monitoring wells to be installed for underground water sampling.

Sampling Locations

Number of samples

Number of wells

Well depth

Main Refinery Area

2

1

Final Production Tank Farm.

2

1

Up Gradient of the site (North).

2

1

Mid-point (Low lying Central Area)

2

1

Down gradient (South)

2

1

Solrec Recovery Plant Site

1

1

Slope down side of Timprell Tip.

1

1

Outside Area of Concern (Background sample)

2

1

The collection of samples at each of the designated area of concern should be close enough to be representative of the area. Monitoring wells designed with screened intervals intercepting the saturated zone at the upper portion are suitable for assessing the occurrence of release to the ground water. Consideration of the site geology such as the length at which release is expected to occur, groundwater flow path and transport characteristics of the potential contaminant of concern should be made before sampling (USEPA, 1995). A single ground water sampling event may not be sufficient to establish a release, so multiple sampling or permanent wells are proposed for complementary purpose.

With this strategic arrangement of bore holes, it would be possible to obtain ground water which could be interrogated for non-aqueous phase liquid, oily sheen and samples for laboratory analysis to know if there is organic or inorganic contaminants in the water sample. The observation of high or low pH solution would be suggestive to changes in natural status of the aquifer which could facilitate the mobilization of contaminants of concern.

Soil Sampling and Analysis

A soil sampling program is being proposed having identified a probable significant pollutant linkage through volatile emission, dust generation, direct contact to human health, fauna and infrastructure. The object of this is to establish if there is a complete pathway for the source emission to reach the receptors. This would involve sampling and analysing core soil samples from designated target areas so as to better characterize the site. A technical bias or judgemental sampling would be used since information has been known about the areas of concern. Sampling can also be carried out for cracks on the walls of legacy structures present on site to reveal the presence of contaminants.

Table 4: Proposed sampling locations, number of samples and sampling zones or depth.

Sampling Locations

No of Samples

Core depth

Main Refinery Area

3

Surficial

Final Production Tank Farm.

3

Surficial and Saturated

Slope down side of Timprell Tip

2

Saturated zone.

Gasoline storage tanks on Whittam Hill.

2

Surficial and Saturated zone

Underground storage tanks

2

Saturated zone

Outside the area of concern (background sample)

4

Surficial and saturated zones.

The surficial sample which be able to detect if a release has occurred or not but a saturated sample would be representative of an integrated sample affected by the environmental quality of enormous zones of unsaturated soil, capillary fringe and aquifer material. The analysis of the samples should be judgmental for cost effectiveness. Because the contaminants of concern have been identified in the preliminary site investigation, there would less need for a broad spectrum of analytical parameters instead; analysis should be streamlined to the identified contaminants of concern which are mostly petroleum based organic contaminants and a few inorganics. Soil core samples can be observed for non-aqueous phase liquid in sample which usually have characteristic black dint. Detection of organic contaminants in the analysed samples above background concentration or within the reasonable confidence protocol would mean the empirical confirmation that a release has occurred. Noteworthy that drilling fluid that could contaminate the well should not be used as not to have false positives and the environmental professional has to demonstrate that any contamination observed is not artificial but represents the site contamination state. The occurrence would be suggestive of a significant pollution pathway.