Environmental Services

Leighton's environmental services commonly begin in the early phase of a real estate transaction, often during due diligence, but may be considered necessary at any stage of development or redevelopment. Through the regulatory process and site remediation, our environmental professionals are here to help our clients from the ground down with the following services:

Phase I Environmental Site Assessments

Phase I Environmental Site Assessments (ESAs) are performed to identify potential recognized environmental conditions. The four main components to conducting a Phase I ESA include a thorough records review of historical land uses, a site reconnaissance to evaluate current conditions of the site and surrounding properties, interviewing landlords, tenants, and site neighbors to obtain further information of the site's history and to report findings to the client and stakeholders.

We have assessed more than 4,000 sites for industrial, commercial, agricultural, and undeveloped and redeveloped (brownfields) properties ranging from small lots to thousands of acres of parcels. Leighton performs all work in compliance with applicable standards as described below:

  • Phase I Environmental Site Assessments for commercial properties (ASTM E1527-05)
  • All Appropriate Inquiry
  • Transaction Screening Assessments (ASTM E1528)
  • Asbestos-Containing Construction Materials (ACCM) Surveys (EPA, AHERA), if required as part of the Phase I ESA
  • Lead-Based Paint Surveys (EPA and HUD residential LBP guidelines), if required as part of the Phase I ESA

Phase II ESA/Remedial Investigations

If a Phase I ESA suggests the presence of possible contamination or if contamination is known to exist at a site, then additional investigation may be warranted. Leighton has conducted thousands of Remedial Investigations(RI), also referred to a Phase II ESAs, to further evaluate sites. These investigations are intended to assess limits of contamination, characterize the type of contaminants, and evaluate contamination migration and/or human health risks.

Our environmental scientists have extensive experience working with various drill rigs; hydraulic push sampling equipment; and soil gas probes for the collection of air, soil, soil vapor, and groundwater samples to support the following types of studies and investigations:

  • Soil and groundwater investigations
  • Soil vapor surveys
  • Hydrogeologic investigations/studies
  • Light Non-Aqueous Phase Liquid (LNAPL) or Dense Non-Aqueous Phase Liquid (DNAPL) source area characterization
  • Wireline geophysical logging and subsurface profiling
  • Contaminated sediment assessment and dredging in lakes, lagoons and canals
  • Supplemental Site Investigation (SSI)
  • Feasibility Studies (FS)
  • Pilot Testing
  • Methane gas monitoring and mitigation
  • Vadose zone modeling
  • Groundwater and contaminant transport modeling
  • Human health and environmental risk assessment

Phase III Environmental Feasibility Study and Remediation

Feasibility Study

Based on results of the site investigation, Leighton will design an appropriate remediation program for the specific site. Prior to system design, a Feasibility Study (FS) will be completed evaluating several remedial alternatives. Leighton will examine alternative mitigation measures given the site conditions, regulatory requirements, type and extent of contaminants, and time frame available to conduct the remediation program. This feasibility study will examine several methods to determine the most cost-effective and timely approach to site remediation. Specific technologies may include:

  • No Action
  • Soil Vapor Extraction (SVE)
  • Dual Phase(DPE)/Two-Phase(TPE)/Multiphase Extraction(MPE)
  • LNAPL or DNAPL assessment, removal/remediation
  • Surfactant enhanced LNAPL/DNAPL removal and Total Fluids Recovery
  • Groundwater pump and treat / plume control
  • In-Situ Enhanced Bioremediation (EISB – aerobic or anaerobic) with or without bioaugmentation
  • Chemical oxidation using hydrogen peroxide/fenton reaction, sodium persulfate, or potassium permanganate
  • In-well stripping and recirculation
  • Permeable Reactive Barrier (PRB) In-Situ Oxygen Curtain (ISOC)
  • Soil excavation and disposal or onsite treatment
  • In-Situ thermal treatment / steam injection
  • Contaminated sediment removal and dredging from lakes, lagoons and canals
  • Monitored natural attenuation
  • Soil fixation

Environmental Remediation

Because Leighton has more than four decades of experience in providing environmental engineering and construction services, we can provide comprehensive turn-key environmental remediation solutions. We will bring all of our experience in civil and environmental engineering, geology, hydrogeology, field sampling, and construction to support clients in the following areas:

  • Risk-Based Corrective Actions
  • Pilot testing for remedial treatment systems
  • Corrective Action Plans/Remedial Action Plans
  • Remedial system design, construction, operation and maintenance
  • Closure criteria development and closure negotiation with lead agency deed restriction
  • Transfer of environmental liability

Preliminary Environmental Assessment (PEA)

Under the jurisdiction of the State of California Environmental Protection Agency, Department of Toxic Substances Control, Leighton conducts Preliminary Environmental Assessments (PEAs), if the preceding Phase I ESA has identified conditions that have or could lead to the contamination of a school site and present a health threat to site occupants. Through a PEA, Leighton’s environmental professionals identify chemicals of potential concern (COPCs), and develop a field sampling and laboratory analysis plan. If chemicals of concern (COCs) are found at the site, then a health risk assessment is performed to evaluate the need for remedial actions or mitigation before use of the property for the proposed development.

Underground Storage Tank (UST) Removal and Closure

During a project that involves Underground Storage Tank (UST) removal and closure, Leighton provides all necessary services including permitting with the local agencies, site preparation, UST removal, management of hazardous waste subcontractors who triple-rinse, haul and dispose of the tank(s). After the USTs have been properly removed, our environmental professionals will collect the necessary confirmation soil samples for analytical testing prior to backfilling. Leighton also provides geotechnical observation and testing for the backfill, compaction and resurfacing of the project site. All work is conducted under a site specific Health and Safety Plan (HSP) compliant with OSHA regulation 29 CFR 1910.120. At the completion of UST removal activities, Leighton prepares a report summarizing subsurface geologic conditions and levels of contamination, if present.

Groundwater Monitoring and Sampling

Leighton provides groundwater monitoring and sampling services for projects during all phases of the assessment and remediation process. These services are intended to characterize groundwater quality and assess whether or not groundwater on site is impacted by previous or nearby activities. Leighton’s environmental team works efficiently to complete projects to avoid delays and to reduce costs. Understanding the environmental compliance sampling requirements, our field personnel have experience in performing the following types of groundwater sampling:

  • Quarterly groundwater sampling for petroleum hydrocarbons, chlorinated solvents, heavy metals or other contaminants
  • Collection and preservation of bioremediation parameter sampling for in-situ anaerobic bioremediation of chlorinated hydrocarbons
  • Collection and preservation of bio culture (i.e. Dehaloccoides) samples and shipping these samples to appropriate laboratories for testing
  • Collection and preservation of bioremediation feasibility study samples
  • Collection of hydropunch samples for pre-screening
  • Collection of remediation progress samples
  • Low flow purging and sampling
  • Forensic sampling for product characterization and other legal purposes
  • Preliminary evaluation of the data in the field for defensibility (measuring depth to water two or three times, checking field parameters with historical parameters, verifying the instrument calibration etc)
  • Waste Discharge Requirements (WDR) monitoring for enhanced in-situ bioremediation and hexavalent chromium in-situ chemical reduction sampling
  • Performance based sampling with zero tolerance for cross contamination, completion of chain of custody forms, sampling field parameter forms, health and safety, and data accuracy
  • Sampling in hard-to-access areas, such as airports, maximum security facilities and public right-of-ways

Regulatory Compliance Services

We assist clients in developing strategies for responding to and complying with regulatory agency requirements that involve critical issues such as Notification of Potentially Responsible Parties, Remedial Investigation/ Feasibility Study (RI/FS), and Clean-Up and Abatement Orders. Our consultants work with numerous regulatory agencies at all levels of government regarding major environmental compliance issues such as:

  • Acquisition of permits
  • Environmental compliance auditing
  • Environmental permitting
  • Hazardous materials inventory
  • Storm Water Pollution Prevention Plans
  • Storm water monitoring

Litigation Support

Leighton’s environmental professionals include registered professional engineers and geologists with expertise in source identification, remediation, cost estimation, forensic engineering and chemical analysis and historical photo-interpretation. Real world experience combined with theoretical and scientific expertise allow Leighton to provide technical litigation support to assist in determining effective legal strategies. This has allowed Leighton staff to achieve success at trial, in mediation or in responding to regulatory agency orders. Leighton also produces a variety of data visualization formats which serve as persuasive tools in negotiation or at trial.