© 2000,

AAPG/DEG

, 1075-9565/00/$15.00/0Environmental Geosciences, Volume 7, Number 4, December 2000 208–212

208

E N V I R O N M E N T A L G E O S C I E N C E S

American Association of Petroleum Geologists Pacific Section Meeting Abstracts,June 19–22, 2000, Long Beach, California

REAL ESTATE REDEVELOPMENT OF HYDROCARBON-IMPACTED PROPERTIES

TREES SUCK . . . BENZENE, TOLUENE, ETHYLBENZENE, AND XYLENES COMPOUNDS FROM SHALLOW SOILS AND GROUNDWATER

Karen Blake, OXY USA, Inc., Houston, TX

Under many oil field sites, shallow soils and groundwater arecontaminated with benzene, toluene, ethylbenzene, and xylenecompounds. I propose using phytoremediation, specifically

Lir-iodentdro tulipifera

, Yellow Poplar, in the cleanup of the site.Phytoremediation processes include enhanced rhizosphere

biodegradation, hydraulic control, phytodegradation and phyto-volatilization. Plant roots supply nutrients to the microorgan-isms within the soil, increasing microbial activity, which in-cludes biodegradation of organic contaminants. Root growthand degeneration loosen soils, providing aeration and watertransport pathways. Water uptake and transpiration processesmove large quantities of water through the contaminated zones,allowing trees to become sinks for contaminants and providingfor some hydraulic control. Initial core sampling will provideinformation on the hydraulic conductivity, thus refining the sol-ute transport models.

Phytoremediation processes and groundwater parametersmust be understood to refine the remediation effort. Oncecollected, data will be analyzed to obtain the following:

•

Estimation of the natural attenuation rate;

•

Spatial understanding of the hydraulic conductivity;

•

Spatial-temporal relationship of water uptake and rootactivity; and

•

Spatial-temporal degradation rate of contaminants insoils and groundwater.

The effectiveness of phytoremediation with respect to ben-zene, toluene, ethylbenzene, and xylene compounds in shal-low soils and groundwater will be determined. If successful,phytoremediation will be a cost-effective, aesthetically pleas-ing method of remediation with wide applications.

SITE REDEVELOPMENT STRATEGIES FOR DORMANT OIL AND GAS FACILITIES

David Daddario, North American Realty Advisory Service, LP Lawrence Livermore National Laboratory, Livermore National Laboratory, New York, NY

Removing environmentally impaired land and building assetsfrom the corporate balance sheet can provide significant returnsto oil and gas companies. However, environmental cleanupcosts, as well as regulatory, political, and community issues canbe stumbling blocks. New tools and methods are now availableto resolve “distressed” site redeployment issues. Plus, federaland state regulators are now helping to streamline the envi-ronmental approvals’ process for contaminated properties withredevelopment potential. This session will address the latesttechniques to uncover redevelopment opportunities and:

•

Reduce cleanup costs and minimize environmental lia-bilities;

•

Manage regulatory issues and community affairs; and

•

Structure and close optimum transactions.

For example, in California several oil terminal and refinerysites have recently been repositioned in the marketplace for pro-ductive new uses. The key to moving these projects ahead was incoordinating the site reuse opportunities with remediation plansand effectively communicating the objectives to regulators, de-velopers, and communities. Case studies will be used to illustratehow corporations are succeeding in redeploying distressed assets.

BEYOND PHASE I ENVIRONMENTAL SITE ASSESSMENTS—CONDUCTING BUSINESS ENVIRONMENTALRISK ASSESSMENTS OF OILFIELD ACQUISITIONS

Roger Funston, Kennedy/Jenks Consultants, Bakersfield, CA

Environmental due diligence investigations for proposedoil field acquisitions are typically conducted for two differ-ent purposes. In the first case, an oil company desires topurchase an oil field to conduct on-going crude oil and natu-ral gas production operation. In the second case, the ownerof the property (an oil company) desires to sell an existing

A A P G P A C I F I C S E C T I O N A B S T R A C T S

209

oil field operation to a real estate developer for residential,commercial, or industrial redevelopment.

The American Society of Testing Materials (ASTM) has de-veloped a standard practice for conducting Phase I Environ-mental Site Assessments (Phase I Assessment) associated withthe transfer of commercial property (E-1527-97). The primaryobjectives of the ASTM standard practice is to identify appar-ent conditions of environmental concern and conduct adequatedue diligence so that the buyer can avail himself of the “inno-cent purchaser provision” under Comprehensive EmergencyResponse, Compensation, and Liability Act (CERCLA). Theseobjectives have limited relevance for most acquisitions of oilfield properties. Most oil field properties have environmentalimpairments. The threshold questions relate to the allocation ofrisk for current and future liabilities between the buyer andseller. There is a petroleum products exclusion under CER-CLA. An Environmental Business Risk Assessment goes be-yond the traditional Phase I Assessment to better meet the busi-ness needs of purchasers of oil field properties. The scope ofthe Environmental Business Risk Assessment is tailored to thelevel of sophistication and the risk tolerance of the buyer andthe nature of the deal. Buyers of oil field properties can rangefrom oil companies with environmental staffs to real estate de-velopers who have limited knowledge of oil field operations.Sophisticated buyers may only need assistance identifying “ex-ception” issues and estimates of the most likely cost and worstcase scenario costs associated with these identified current andfuture liabilities. These buyers can generally estimate futurewell abandonment and facility demolition costs in-house.These buyers may also be able to estimate in-house remedia-tion costs associated with shallow crude oil–impacted soil andother conditions typical of oil field operations. Less sophisti-cated buyers may need more assistance in these areas. For buy-ers interested in redevelopment of oil fields, the threshold ques-tion is can the site be prepared for redevelopment at a lowenough cost in order that the developer can make a desired rateof return on their investment. One way to address this issue isthrough a focused Phase I/Phase II Assessment conducted instages. The primary objective of Phase I is to gather justenough information to select locations for the focused Phase IIinvestigation. The objective of the first stage of the Phase II In-vestigation is to confirm the general nature and extent of envi-ronmental impairments to ascertain whether it makes sense tocontinue. In some cases, this initial investigation will suggestthat the cost of site remediation will exceed an economicthreshold that makes redevelopment of the site unattractive. Ifthe initial Phase II Assessment work is favorable, additionalwork is conducted consistent with the level of business risk anduncertainty the developer is willing to accept.

Historically, oil field sellers have provided either a full orpartial indemnification to the buyer for environmental condi-tions that existed before the date of sale or have provided a duediligence period after the date of sale for the buyer to conductadditional environmental investigations. In the later case, the

buyer could make claims against the seller for environmentalconditions that were discovered that had a liability above a cer-tain dollar amount as a post-closing adjustment to the purchaseprice. These types of deals are less common today. More typi-cal today is an “as-is” sale where the seller is willing to enter-tain adjustments in the purchase price for environmental im-pairments identified by the buyer in a due diligence periodbefore closing. The Environmental Business Risk Assessmentprovides information the buyer needs to make informed busi-ness decisions about allocation of risk as a part of the negotia-tion of the Purchase and Sales Agreement.

THE BUSINESS OF MAXIMIZING VALUE AND REDUCING LIABILITY: PROPERTY MANAGEMENTAND DISPOSITION

Helen Ordway, Chevron USA Inc., Bakersfield, CA

Environmental remediation of both producing and nonproduc-ing oil field properties has historically been viewed as a cost in-tensive, bureaucratic process resulting, at best, in low revenueproperty. Development of remediation technologies in combina-tion with ongoing efforts to streamline regulatory processes haveprovided the opportunity for a business approach to remediationand disposition of property. This business approach utilizes anal-ysis and implementation of cost-effective and innovative remedi-ation strategies geared to proactively engage the regulatory pro-cess and create maximum value in property disposition.

ENVIRONMENTAL LIABILITIES ASSOCIATED WITH OIL INDUSTRY OPERATIONS

THE 1985 ROSS STORE EXPLOSION AND OTHER GAS VENTINGS, FAIRFAX DISTRICT, LOS ANGELES

Douglas Hamilton, Consulting Geologist, Atherton, CA and Richard Meehan, Consulting Civil Engineer, Menlo Park, CA

Methane gas ventings in the Fairfax District of Los Angelesresulted in the explosion of a Ross Dress for Less departmentstore in 1985 and the evacuation of several buildings in 1989.

The Fairfax District overlies part of the old Salt Lake oilfield and is

z

0.50 mile from the LaBrea Tar Pits. The oil field,once developed by

.

400 wells, was largely abandoned prior tobeing redeveloped by slant drilling starting in 1962. Since then,production of oil, salt water, and gas has been continuous withthe water being reinjected into the field since 1980. The dis-posal reinjection was into a block adjacent to the Third Streetfault, which projects to the surface near the surface ventingsites. Injection was at surface pressures of up to 770 psi, givingrise to a gradient of

z

0.7 psi/ft within the subsurface near thepoint of injection. We conclude that this resulted in episodicfracturing of the Third Street fault. The fault, acting as a valve

210

E N V I R O N M E N T A L G E O S C I E N C E S

structure, was temporarily jacked open by the local fluid over-pressure and while open served as a conduit for escape of pres-surized methane to the near surface. With depressurization, thefault conduit would collapse and the venting cease.

Similar effects of fault activation by fluid pressure excur-sions have been demonstrated in connection with the 1963failure of Baldwin Hills dam in the Inglewood field, withseismicity triggering elsewhere, and also in paleo effectspreserved in vein structures.

Clearly, the phenomenon of methane venting in the urbanenvironment can be hazardous, especially if no provisionhas been made to control it at the surface. But we proposethat adequate response to this hazard should include devel-oping an integrated understanding of both surface and sub-surface conditions, starting, where oil field activity is involved,with the geology and operations within the producing zone.

IMPROVED ANALYTICAL TOOLS FOR EVALUATING PETROLEUM-IMPACTED SITES

Kirk O’Reilly, Chevron Research and Technology, Richmond, CA

Recent advances in the analytical methods available to evalu-ate petroleum in environmental samples can provide valuable in-formation for remediation project managers. These methods canbe used to determine responsibility, assess risks, meet regulatoryrequirements, and select the appropriate corrective action. Thegoals of this presentation are to introduce some of these methodsand to describe how they can be applied to reduce project costs.Tools for rapid data evaluation will also be presented. Case stud-ies that resulted in over $1,000,000 in savings will be discussed.

TESTING A FIELD-BASED MODEL FOR HYDROCARBON VAPOR MIGRATION

G. Ririe, Unocal, Brea, CA, Robert Sweeney, and Seth Daugherty, Orange County Health Care Agency, Santa Ana, CA; Peter Peuron, Environmental Geoscience Services,Long Beach, CA

To better evaluate risk associated with hydrocarbon vaportransport, vertical soil gas profiles were collected at several hy-drocarbon-impacted sites. A consistent pattern was found in theprofiles of soil vapor composition in shallow uncontaminatedsoil. Generally, oxygen concentrations decreased from atmo-spheric levels at the surface to near zero just above the contami-nation. Hydrocarbon gas concentrations are inversely related tothe oxygen. For soils with oxygen concentrations

.

5%, hydro-carbon gases are generally near background detection levels. Formost profiles, hydrocarbon gas concentration is highest within thecontaminated zone, decreasing rapidly upwards in the first 3–5 ft.Depth to contaminated soil is usually the most critical factor con-trolling whether hydrocarbon vapors will reach the surface.

Many different models are in use to screen sites for vaporrisk. They have not, however, been calibrated with fielddata. One such model (Orange County) that is currently be-ing used in California contains a provision for vapor attenu-ation by a concrete slab. This model is easy to apply, is welldocumented, and has been accepted by other agencies; how-ever, the model predictions usually do not match the field data.This can be partly attributed to the model’s attenuation factor.

In this paper, an approach is presented that modifies the“vapor attenuation” input for the Orange County model toinclude contribution from biodegradation in addition to theconcrete slab. Case studies are shown to illustrate how fielddata have been used in the Orange County model to evalu-ate potential benzene health risk due to the vapor pathway.

FINDING ABANDONED SUMPS, TANKS, AND OTHER OIL FACILITIES

Harold Sugden, Consultant, Bakersfield, CA

As oil wells and facilities are abandoned and “cleaned up” inCalifornia, commercial and public buildings, recreational facili-ties, and houses are being constructed on some of those sites. Thepresence of abandoned wells, former production facilities, sumps,tanks, pipelines, natural seeps, and other oil field artifacts are notalways detected during a Phase I environmental survey. Due dili-gence requires that these oil field remnants be located and a deter-mination made as to whether or not they pose a threat to the pub-lic, the environment, or the economic viability of a property.

One way to find potential problems is the examination ofaerial photographs. The problem with aerials is that they are notalways taken at the right time. The records and reports of theCalifornia Division of Oil, Gas, and Geothermal Resources areneeded to find abandoned wells and the limits of oil fields. U.S.Geological Survey topographic quadrangles sometimes showthe locations of sumps, tanks, and oil wells but may not be suffi-ciently accurate to locate them for environmental testing. Unfor-tunately, accurate records of the locations of buried sumps andfacilities have not always been generated. Anecdotal informationusually consists of arm waving, rough pacing, and the lamentthat after the last merger the old facility maps and diagrams werethrown out. Natural oil and gas seeps, although well docu-mented, can be difficult to locate precisely. The result is that thelocation of all abandoned facilities is not always possible.

ENVIRONMENTAL HYDROGEOLOGY

REMEDIATION IS ENHANCED OIL RECOVERY: KNOW YOUR SOURCE

G. Beckett, Aqui-Ver, Inc., La Jolla, CA

Non-aqueous phase liquids (NAPLs) represent direct and in-direct sources of potential risk. NAPL can be a long-livedsource of groundwater and vapor impacts because a small vol-ume of NAPL phase can feed very large daughter plumes. Formany years, the general environmental industry has built a da-

A A P G P A C I F I C S E C T I O N A B S T R A C T S

211

tabase of limited remediation success, particularly in terms ofmitigating source NAPLs. Any method of cleanup, no matterhow fundamentally suited, will likely fail if the zones of NAPLimpacts are not effectively targeted. This is analogous to en-hanced oil recovery in the petroleum field; recovery enhance-ments occur only when targeting the zones containing oil. Al-though cleanup to pristine conditions is usually not viable,cleanups can do a far better job at reducing potential risks whenNAPL factors are considered. This said, cleanup technologiesalso have specific limitations, and success must be defined interms of the risk–benefit of the applied actions. Full treatmentof the NAPL zones may be difficult, but it is usually possible tomitigate risk through remediation and management.

This paper provides a few field examples of cleanup failureand documents the specific reasons why the failures occurred.In none of the cases was the failure attributable to geologiccomplexity or the “tailing” effect of fine-grained layers. In alast example, cleanup design shortfalls were mitigated by pro-actively considering the NAPL target zones. Cleanup occurredin less than

,

6 months using simple technologies.

CASE STUDIES USING RESERVOIR CHARACTERIZATION TO IMPROVE REMEDIATION SYSTEM DESIGNAND OPERATION

Vivian Bust, Consulting Geologist, Irvine, CA

Improved remediation system design and operation resultedfrom effectively using reservoir characterization to identify hy-draulic flow units and connectivity of sediments in hydrocar-bon-affected aquifer-aquitard systems. Reservoir characteriza-tion methods used in petroleum exploration and productionwere applied to near-surface sedimentary sequences to de-scribe the subsurface hydrogeologic setting. The methods usedincluded continuous coring, detailed core description, routineand special core analyses, analog sedimentary environments ofdeposition, well testing, and simulation and development ofoperating and surveillance plans. The objective of this ap-proach was to better quantify aquifer storage and flow proper-ties, identify fluid migration pathways and permeability barri-ers, develop deterministic geologic/property models, and moreeffectively evaluate remediation design alternatives and operat-ing scenarios. Cost savings for capital equipment, operations,and monitoring resulted from using site-specific hydrogeologicproperties in remediation system design.

This paper will discuss remediation case histories of siteslocated in Southern California that include (1) life-cycle de-sign of a multi-technology remediation system and networkof dual-completion wells that were installed simultaneouslyduring construction of a 14-story office building and eight-story parking structure; (2) site-specific considerations inevaluation of in situ bioremediation and cyclic steam injec-tion remediation alternatives; (3) using stratigraphy in astrategic way for design and installation of a french drain;and (4) planning, drilling, and completion of a horizontal re-

mediation well for removal of floating product in thin-bed-ded sands directly overlying fractured bedrock.

SELENIUM REMOBILIZATION DUE TO DESTRUCTION OF WETLANDS IN THE IRVINE SUBBASIN, ORANGECOUNTY, CALIFORNIA

Barry Hibbs, California State University–Los Angeles, Los Angeles, CA, Monica Lee, California State University–Los Angeles, Los Angeles, CA, and James Walker, California State University–Los Angeles, Los Angeles, CA

The Irvine Subbasin forms part of the coastal edge of Or-ange County, California. Prior to 1900, the central part ofthe Subbasin was marshland. After 1900, drainage ditchesand channels were constructed to drain the marshes for agri-culture. Today, the drainage ditches still exist in the IrvineSubbasin, which is undergoing massive urban growth. Shal-low groundwater discharges into these channels, and thesurface water eventually flows into Upper Newport Bay, athriving habitat. Surface flows in these channels usually ex-ceed the U.S. Environmental Protection Agency chronic cri-terion for selenium (Se) of 5 ppb for protection of aquaticlife. Se in surface flows is caused by groundwater inflows.

The highest concentrations of Se in shallow groundwaterin the Irvine Subbasin coincide with the marshland areasthat were displaced by agriculture. Concentrations of Se ingroundwater in the former marsh areas often exceed 50 ppband are as high as 200 ppb. In areas where marshes were ab-sent, concentrations of Se in groundwater are usually 10 ppb.The marshes are presumed to have been oxygen-deficient,following modern analogs in undisturbed habitats along theCalifornia coast. In oxygen-deficient marshlands, Se is usu-ally in the form of selenite or elemental Se, two relatively in-soluble forms of Se that collect in the sediment at the bottomof the marsh. We hypothesize that the elevated concentrationsof Se in groundwater where the marshes once existed are a di-rect result of the destruction of the marsh. Today, oxygenatedgroundwaters flow through the soils where the marshes onceexisted, remobilizing Se as selenate, a water-soluble form ofSe that is highly mobile in aquifer systems.

REDUCTIVE DISSOLUTION AND PRECIPITATION OF MANGANESE DUE TO BIODEGRADATION OFPETROLEUM HYDROCARBONS

Leslie Klinchuch, Chevron USA Inc., Bakersfield, CA and Thomas Delfino, Geomatrix Consultants, Oakland, CA

Dissolved manganese affects the aesthetic quality of ground-water used for domestic purposes. Reducing conditions due tonatural biodegradation of petroleum hydrocarbons in contactwith groundwater can cause dissolution of manganese fromaquifer sediments. However, the reaction is reversible by

212

E N V I R O N M E N T A L G E O S C I E N C E S

chemical oxidation downgradient of the bioremediation shadow.Geochemical modeling (MINTEQA2) predicts the redox con-ditions for manganese precipitation from groundwater back toaquifer sediments. The reaction rate for manganese precipita-tion is related to the advective and dispersive transport of dis-solved oxygen in groundwater. At a petroleum release site incentral California, the reaction rate was observed to followfirst-order kinetics. By knowing the site-specific aqueousgeochemistry and reaction kinetics, measures can be taken withreasonable certainty to construct water supply wells to avoidproducing water with unacceptable levels of manganese.

DO OIL AND WATER (BANKING) MIX? MINIMIZING THE RISK WHEN ARTIFICIALLY RECHARGING GROUNDWATER IN AN OIL-PRODUCING AREA

William Pipes, Geomatrix Consultants, Fresno, CA and James Waldron, Chevron USA Production Co., Bakersfield, CA

Water banking using infiltration basins has a number oftechnical criteria it must meet for it to be a success — avail-able water of sufficient quality, available land with little or noinstitutional restrictions, clean permeable soils, groundwaterat the right depth, and little or no impact to nearby groundwa-ter users. What do you do when all the technical criteria havebeen satisfied and then discover contaminated soil in thearea? Can the environmental impact be managed such that thepotential risk is minimized at a reasonable cost and the waterbanking project allowed to go forward? The answer is a qual-ified yes, given that the nature and extent of the contaminatedsoil, changes in groundwater conditions due to water bankingactivities, and the potential effect on groundwater quality arewell understood and contingency measures are in place to ad-dress potential water quality impacts should they occur. Thispaper presents a case study where contaminated soil was dis-covered within a proposed water banking project area andhow the potential risk from the impact was minimized at areasonable cost and to the satisfaction of the stakeholders.

MTBE TRACER STUDY TO DEFINE GROUNDWATER TRANSPORT PARAMETERS: ESTERO MARINE TERMINAL

Daniel Tormey, Entrix Inc., Ventura, CA, James Waldron, Chevron USA Production Co., Bakersfield, CA, and Matt Carpenter, Entrix, Inc., Ventura, CA

Methyl Tertiary Butyl Ether’s (MTBE) chemical propertieslead to rapid transport in groundwater systems. A short-dura-tion spill of MTBE-bearing oil to a well-studied and monitoredhydrogeological system allows determination of chemical andhydrogeologic conditions in the vicinity of the spill site. Themeasured rate of expansion of the MTBE plume, coupled withknown soil and hydrologic properties, allows determination offield-scale MTBE transport parameters; the trajectory of theMTBE plume provides independent, chemical, confirmation ofgroundwater flow paths inferred based upon hydrogeologic data.

Chevron’s Estero Marine Terminal, located on Califor-nia’s Central Coast near Morro Bay, received crude oil fromKern County production and loaded it to ships for transportfrom the 1930s to 1999. The terminal has been subject to as-sessment and monitoring activity on at least a quarterly ba-sis for 5 years. A plume of cutter stock (a thinner approxi-mately equivalent to a diesel composition) mixed withheavy crude oil is at the water table, but the low solubilitymaterial has produced a very small halo of hydrocarbon-bearing groundwater. No benzene or MTBE had been de-tected in site monitor wells. During pipeline abandonment

activity,

z

200 gal of a gasoline-like light-cycle oil wasspilled to the ground and infiltrated 2–3 ft to groundwaterover several days. The light-cycle oil contained

z

2 mg/LMTBE. Subsequent analysis of groundwater samples fromthe monitoring well array sequentially provided detectionsof MTBE and benzene. These data constrain calculations offield-scale transport parameters at the site and provide atracer of the groundwater flow path from the spill area.

The observed transport rate for MTBE is approximatelytwice that of benzene. This relative velocity agrees wellwith predictions based upon the organic carbon content ofthe soils. The observed MTBE transport rate is approxi-mately equivalent to the predicted groundwater flow veloc-ity. This observation indicates little or no retardation ofMTBE. The plume of MTBE appears to have stabilizedover an

z

3-month period, suggesting that some attenuativemechanism is at work.

The site is located adjacent to a coastal stream and the Pa-cific Ocean. Past study has indicated a three-componentflow field in the area of the spill, with the coastal stream dis-charging to groundwater, and a net zero gradient towardsthe ocean caused by symmetric tidal variation. The track ofthe MTBE plume is along the flowpath inferred based uponhydrologic data alone. The track of the plume also suggeststhat the groundwater system ultimately discharges to the Pa-cific Ocean, but the flowpath is deflected strongly to thesouth based upon discharge from the coastal stream togroundwater.