Phytoremediation used in Oklahoma project to control migration of groundwater plume
By Myna D. Letlow, Dina C. Kuykendall, Chris C. Clodfelter, Baker Hughes
Today’s E&P companies and service providers are being driven by communities, regulatory requirements, customers, employees and shareholders to integrate sustainability concepts into all aspects of operations and project management. Doing so can not only minimize environmental impacts but also yield benefits ranging from cost savings and increased efficiencies to positive reputation and revenue growth.
Environment is one of three pillars of sustainability referred to in the 2005 World Summit on Social Development. The other two pillars are society and economics. The three pillars are not mutually exclusive and can be mutually reinforcing. All three must be reconciled to achieve sustainable development that meets the needs of people and the Earth in the present without compromising the ability of future generations to meet their own needs.
Baker Hughes is among companies that have integrated sustainability concepts into the management of environmental projects so that the projects not only minimize environmental impacts but also positively impact the communities in which they occur and benefit the company’s bottom line.
Framework for success
The company has built a strategic framework that broadens thinking beyond the traditional project management style to incorporate a range of environmental, social and economic considerations. The environmental aspect of the framework goes beyond regulatory compliance to encompass biodiversity, habitat and species protection, efficient energy use and reduction in greenhouse gas emissions. Evaluating these factors as they relate to a project can enhance both project and company performance, producing more environmentally responsible solutions along with better time and cost management.
The social aspect incorporates public interests. For example, included in a site remediation project is participation in discussions regarding the proposed remedy’s impacts on the community, end uses of remediated areas and residual environmental impacts and their effects on property values and quality of life.
The economic aspect addresses improving profitability and value of products and services for this generation without jeopardizing the capabilities of future generations. Key performance indicators include increased employee productivity and satisfaction, increased profit margins with procurement, and corporate image and reputation enhancement to attract greater investment and share price.
Site remediation project
Stakeholders in site remediation projects are more active than ever before in demanding that remediation technology selection include an evaluation of the probability of these and future projects having a net environmental and societal benefit. Environmental sustainability in these types of projects requires seeking community input and incorporating their views into the planning process. It also requires standardizing equipment and systems and using local sourcing of products and services to realize cost efficiencies.
The pillars of sustainability were recently applied in a remediation project at the company’s manufacturing facility in Claremore, Okla. The facility is located in an area of mixed land use and is adjacent to commercial and industrial facilities, schools, a senior center and recreational facilities. Additionally, there are residential areas nearby. No significant habitats or ecological receptors are housed onsite or in the surrounding area.
Historical leaks from underground storage tanks led to contamination with chlorinated solvents, which was first identified in the early 1990s. Since that discovery, a variety of remediation methods have been tried. These included soil excavation and off-site disposal, air sparging/soil vapor extraction, high vacuum multiphase extraction, carbohydrate injection and a groundwater pump-and-treat system. Despite a declining trend in contaminant levels over the past 20 years, progress has been limited by challenging hydrogeologic conditions and the nature of the chlorinated contaminants. Even with the long span of continuous remediation and considerable funding, elevated levels are expected to be present for the foreseeable future.
A meeting between Baker Hughes and representatives from the Oklahoma Department of Environmental Quality (ODEQ) was held to determine how the project might be closed using a risk-based corrective action (RBCA) approach. Remedial objectives agreed to by the group included limiting the groundwater plume to the on-site property, stabilizing or decreasing plume size and concentrations, and putting controls in place to prevent potential human exposures to the affected groundwater.
During the meeting, Baker Hughes proposed phytoremediation – the use of plants to remediate groundwater – as an option to control migration of the groundwater plume. ODEQ responded favorably to the idea, leading to a discussion on the use of a more sustainable remediation strategy that would reduce contaminant concentrations and ensure that no off-site contaminant migration could occur that might impact sensitive receptors.
The revised strategy included phytoremediation as a primary component of a sustainable solution that would not involve continued expensive remediation system operations and maintenance. Other aspects of the strategy included additional source area concentration reduction using in-situ treatments, implementation of a plume management zone and monitoring of natural attenuation, and the use of physical and institutional controls.
Fifty-two trees were planted in available on-site landscaped areas located downgradient of the contaminant source area. Tree growth extracts groundwater and serves a valuable role in preventing off-site migration of groundwater contaminants. The rate of groundwater extraction by the trees will increase over their life as they grow and mature.
Phytoremediation can have distinct advantages over other remedial options, providing a more sustainable approach. After the trees are established, operations and maintenance efforts and associated expenditures are very low compared with groundwater pump-and-treat systems. Costs are limited to periodic inspection by a qualified arborist or experienced landscape contractor and the addition of fertilizer every few years. By the time the project is completed, cost savings in excess of US $500,000 are expected over the previous pump-and-treat approach.
Phytoremediation provides a long-term response action that is particularly valuable for sites with long time horizons and a need for hydraulic control. Once the trees are established, they will extract groundwater over their entire lifetime, which can be 50 years or longer.
Trees reduce greenhouse gases by emitting oxygen and consuming carbon dioxide, which is considered to be a greenhouse gas that contributes to climate change. Rather than consuming energy and contributing to greenhouse gas emissions, as do traditional groundwater pump-and-treat systems, the trees reduce greenhouse gases in the atmosphere, providing a greener and more sustainable remedial option.
When proper consideration is given to aesthetics, phytoremediation is readily accepted by the company, the public, and government. Corridors of phytoremediation tree plantings can also act as a visual screen for industrial facilities, enhancing visual appeal and protecting the company’s reputation as a good corporate citizen and neighbor in the community. When the trees have become fully established, phytoremediation will provide a recognized and cost-effective remedial alternative to the long-term groundwater pump-and-treat system.
Sustainable site restoration
Integrating sustainability into a site restoration project in northeastern US involved remediation and steps to protect or enhance ecosystem services. The site consists of approximately 134 acres, approximately 30 of which were specifically developed for industrial use. The remaining acreage includes wetlands, surface water or other sensitive areas. A 10-acre disposal area was used for building and machinery debris from the early 1960s through the 1970s. The majority of the impacted areas were remediated between 2005 and 2007.
However, an area of soil contaminated with asbestos, heavy metals and some organic compounds remained. Among factors taken into consideration during the evaluation of restoration alternatives was risk to human health and the environment, regulatory requirements, future land use restrictions and community desires.
As a precursor to determining which alternatives to consider, several limitations on the property were agreed upon by internal environmental, legal and financial teams. These included never selling the property, never permitting unrestricted public access and maintaining fencing and security to deter trespassers. All limitations met regulatory requirements and were used primarily to reduce risk to human health and the environment. The restoration alternatives were evaluated within these limitations and with consideration for ecological services, community value and costs.
An additional alternative of restricting site access to protect public health, yet maintain or enhance the developed habitat was considered. A decision support tool was used to evaluate quantitative and qualitative information for 33 environmental, social and economic indicators, such as greenhouse gas emissions, energy consumption, water use and project costs. All indicators were weighted with respect to project-specific importance.
The results of the sustainability analysis were presented as a percentage value for each of the sustainability components – environment, society and economics. Values greater than 50% indicated a net positive impact, and values less than 50% indicated a net negative impact. Generally, the larger and more balanced the triangle within the diagram, the better, or more sustainable, the option.
To address community concerns and provide information to the public on the intended project plan, four public meetings were held over one year. At each meeting, there were mixed opinions as to how the property should be used in the future. An economically focused public contingency wanted the site to be used for residential development to create a larger tax base. Another faction – primarily residents living nearby – preferred that the property remain undeveloped for habitat and watershed protection.
Results of the comprehensive sustainability analysis indicated that maintaining the existing habitat and placing restrictions on future land use was the most sustainable option. Other alternatives involved an engineered cap, or excavation and disposal to a landfill. Either of these would destroy the wildlife habitat and result in a large environmental footprint, making them the least desirable alternatives. In the end, the most sustainable approach was accepted as being beneficial to the community, protective of the environment and most cost-effective for the company.
Because a large portion of the property contains surface water, wetlands and other valuable habitats, the final component of the project was an assessment of the ecological services the site provides. Results indicate the area supports a variety of vegetation and wildlife and provides a high level of ecosystem functions and services. Ecosystems include abiotic – soil and geologic material – and biotic – plant and animal – physical components. Their interaction results in a functional ecosystem that benefits humans in the form of wildlife, fisheries, flood control, recreation and others.
The ecological services evaluation will be used to determine future activities at the site, which may provide economic and environmental benefits. These activities may include placing conservation easements to further protect the environment. Such easements also provide a modest tax benefit to the company. Wetland restoration and mitigation banking are also under consideration.
As illustrated by these examples, sustainability of environmental projects is not limited to protecting human health and the environment. Integrating sustainability strategy into the project management process can also enhance corporate reputation and improve profitability and value. The concepts of sustainability can be applied to any type of environmental project. The key to success is effective communication and collaboration with all stakeholders, including employees and communities.
This article was adapted from SPE 163781, “Integrating Sustainability into Environmental Project Management,” SPE Americas Health, Safety, Security and Environmental Conference, 18-20 March 2013, Galveston, Texas.
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