Todd Engineers

Potential prion migration pathways

Upcoming Todd Engineers’ Talks at AEG and PEMA Events

Emerging Contaminants

However, there are also newer emergent EECs that could potentially contaminate surface and groundwater; these include: (1) Pharmaceuticals and Personal Care Products (PPCPs), with hundreds if not thousands of complex chemicals; (2) nanomaterials, including those derived from geogenic (natural) and anthropogenic (human) sources; (3) platinum group metals (PGMs), which are being emitted in increasing quantities by erosion of automobile catalytic converters and may be impacting groundwater in urban and suburban areas, and (4) prions (misfolded proteins) that are environmentally persistent and recalcitrant and are responsible for amyloidal diseases including bovine spongiform enthalopathy (BSE) or “mad cow disease”. These and other potential ECCs will be discussed in detail at the talk.

Gold Mining in California

Arsenic is often associated with ML-type gold ore deposits, generally occurring as arsenian pyrite and arsenopyrite; these minerals may also contain small amounts of gold (known as auriferous pyrite). To maximize profits, many ML gold mines attempted to recover as much of this gold as possible by processing the ore using chlorination or cyanide leaching of sulfides. In the late 1800s and early 1900s, processed tailings containing considerable amounts of arsenic were discharged to streams and rivers. Flooding of Central Valley agriculture by such tailings disposal caused farmers in 1912-1913 to lobby the legislature for relief. Subsequent agreements between farmers and mine owners resulted in mines agreeing to impound their tailings. By the mid to late 1950s most ML mines had ceased operations. Some mining properties have been reclaimed; many others have not with some retaining impounded tailings.

Recent commercial development and improper reclamation has resulted in litigation (mostly addressing arsenic contamination in tailings and adjacent soil and groundwater) by state and federal agencies, suing under CERCLA and other statues. Litigation settlement and subsequent re-remediation/reclamation of arsenic-impacted areas has been expensive. Two such case studies involving mining properties will be presented: the Central Eureka Mine area in Sutter Creek and the Jamestown Open Pit Mine near Sonora.

Todd Engineers New Staff Certification

Dr. William Motzer

Dr. Motzer has extensive experience in conducting surface and subsurface water quality chemistry and environmental forensic investigations. He is a recognized expert in forensic geochemistry, with particular expertise in stable and other isotopic "fingerprinting" and age dating techniques, water quality/contamination, and emerging contaminant geochemistry. He has been responsible for more than 400 environmental projects throughout California and other western states.

Congratulations Bill!!

Beach Seep Flow

Todd Engineers Presents Talk in GRA Tools and Technology Series

Environmental forensics has been defined as the systematic examination of environmental information used in litigation. For the past decade, techniques such as fuel fingerprinting, stable and radiogenic isotope analyses have been used to determine and assess contaminant sources. However, forensic scientists have other investigative tools and techniques at their disposal, which can be tailored to the investigation; examples are described below. Dr. Motzer will present three case studies of how environmental forensics were used by Todd Engineers to solve environmental problems.

DNA Fingerprinting of Coliform Bacteria

Pit Lake

Using Surrogates to Determine Groundwater Contaminant Sources

Coastal Seep Flow

Using Multiple-Faceted Hydrogeological and Geochemical Investigations

Todd Engineers Presents Two Talks at the NWRI/WaterRF/OCWD Symposium

On Tuesday, January 25 in Session 6b: Modeling of Recharge Basin Performance, Dan Craig, Senior Hydrogeologist with Todd Engineers presented: Optimizing Recharge and Recovery at Recharge Basins in the Pauba Valley and Phyllis Stanin, Vice President of Todd Engineers, presented: Recharge and Supply Allocation in the Ames Valley Basin - Making it Happen.

Optimizing Recharge and Recovery at Recharge Basins in the Pauba Valley

Cross section of VDC Lower Ponds

In order to maximize their recharge and recovery operations, the District has embarked on two recharge optimization studies. For both studies, an improved understanding of the hydrogeology and local-scale numerical modeling were keys to optimizing recharge and recovery.

At the Lower Ponds, alluvial fan and fluvial processes have deposited permeable channel sands that typically result in high infiltration rates and groundwater storage capacity. However, heterogeneity in the alluvial aquifers has created some problems of infiltration in certain areas.

Two local-scale MODFLOW models, based on the District's regional model, have been constructed by Todd Engineers over each area to simulate various scenarios of recharge and recovery. Numerous operational scenarios were evaluated including increased recharge in certain ponds, use of wells adjacent to the basins to control groundwater mounding, and selective operation of key downgradient wells to increase recovery of the recharge water.

Modflow model of VDC Lower Ponds	Modflow model of VDC Upper Ponds

Recharge and Supply Allocation in the Ames Valley Basin - Making it Happen

Modflow simulated flowpaths for Ames Valley

Todd Engineers constructed a groundwater model of the Pipes and Reche subbasins in the western Mojave Desert to verify basin sustainable yield, characterize groundwater flow conditions, and evaluate the hydraulic impacts of the planned recharge facility. The model included complex hydrogeologic features, including faults that serve as partial barriers to groundwater flow.

Todd Engineers assisted BDVWA in development of a GWMP for the basin, which included a description of the state of the groundwater basin, water supply and demand, basin management objectives, basin management strategies, and implementation plan, and a monitoring program (for levels, quality, storage, and subsidence).

Total future pumping allocations may exceed average basin perennial yield during future dry years. Imported water recharge will be conducted to increase storage and supplement supply. Based on future storage changes, pumping reductions may be implemented.

Are You Ready for Senate Bill 6?

DWR is Rolling Out an Implementation Plan for SBx7 6

DWR and the Association of California Water Agencies (ACWA) are currently holding a series of workshops across the state to discuss the program with local agencies that could qualify as monitoring entities, as defined in the law. Todd Engineers will participate in four of the ten workshops in key areas of the state in order to provide feedback to DWR and to be prepared to assist our clients in complying with the program.

DWR has not yet finalized all the details of CASGEM, but they are expecting to release guidelines in September 2010 to help monitoring entities prepare monitoring programs. The deadline for applying to be a monitoring entity is January 1, 2011 and monitoring programs must be submitted to DWR in the spring and summer of 2011.

While the details of the program are still being finalized there are a few things that may prove to be challenging for many areas of the state:

All designated groundwater basins must be monitored, including those with little to no groundwater use. Wells that are part of Public Water Supply Systems with more than 3,000 connections are not eligible for inclusion in monitoring due to Department of Health restrictions. Construction, location, and ownership information must be supplied to DWR for all of the wells in a monitoring program. This information will be publically available on the internet, which may violate established confidentiality agreements between many monitoring entities and well owners.

The ACWA/DWR workshops will continue through the end of August, providing opportunities to voice your opinion on the program. If you cannot attend a workshop, contact us with questions or comments that you would like to see addressed and we will raise them.

Protecting Water Quality: Todd Engineers' Presentations at the 2010 GRA Annual Conference

The three presentations described below are illustrative of Todd Engineers' current projects.

"Old" and "New" Emerging Contaminants

Dr. Motzer gave his talk on Wednesday, September 15, 2010 from 2:30 to 3:00pm in Session 2B: Emerging Contaminants -- From the Source to Groundwater.

City of San Jose South Bay Water Recycling Groundwater Monitoring and Mitigation Program Update

Mr. Craig presented his team's findings on Wednesday, September 15, 2010 from 3:30 to 4:00pm in Session 4B: Recycled Water Groundwater Recharge.

West Coast Basin Barrier Project (WCBBP) Intrinsic Tracer Study

Todd Engineers evaluated natural (or intrinsic) water quality parameters (primarily sodium, calcium, chloride, and sulfate ions) using Brine Differentiation Plots, which proved to be a powerful tool to differentiate the relative amounts of blended injectate, seawater, and baseline groundwater. Brine Differentiation Plots were effective in verifying the amounts of recycled water in WCBBP monitoring wells, identifying the influence of seawater, and in documenting the travel time of injected water to monitoring wells.

Mr. Lin gave his presentation on Thursday, September 16, 2010 from 9:00 to 9:30am in Session 4B: Recyceld Water Groundwater Recharge

Todd Engineers Recognizes Staff Accomplishments

Sally McCraven

Sally McCraven has been promoted to Principal Hydrogeologist with Todd Engineers. Sally will celebrate her 22nd year with Todd Engineers in 2010 and her new title recognizes her substantial contributions to the firm. Her recent and long-term clients, such as the Los Angeles County Sanitation District, Santa Clara Valley Water District, and City of Los Angeles, know her to be a highly responsive project manager and a strong technical lead, who can be relied on to get the project completed successfully. Sally's experience covers a broad range of projects including basin-wide water supply feasibility studies, litigation support, monitoring program design, emerging compounds assessments, groundwater vulnerability studies, and recycled water recharge evaluations, with a particular focus on groundwater protection.

Chad Taylor

Chad Taylor has been promoted to Senior Hydrogeologist with Todd Engineers. Chad joined Todd Engineers in 2007 bringing ten years of hydrogeology experience in California and Colorado. Chad has quickly established himself at Todd Engineers as a key team member and effective project manager. Chad is a licensed Professional Geologist and Certified Hydrogeologist. He has a breadth of professional experience in the development, management, and protection of groundwater, with a focus on water supply.

Congratulations, Sally and Chad!!

Successful High Capacity Well Installed for Metropolitan Water District of Southern California

The design intent of the well was to extract water previously recharged to the area at a design capacity of 2,500 gallons per minute (gpm). The 24-inch diameter well was constructed using a combination of mild steel louver screen and stainless steel wire wrapped screen to maximize open area and conserve material costs. A battery of aquifer tests indicated that the well is capable of producing in excess of 3,000 gpm with less than 30 feet of drawdown! Metropolitan is currently assessing how best to incorporate this new well into their system.

Todd Engineers Presents Groundwater Vulnerability Results at Biennial Groundwater Conference

The presentation discusses the methodology and findings of a recently completed Groundwater Vulnerability Study conducted for the Santa Clara Valley Water District (District) (http://www.valleywater.org). The talk was coauthored by Vanessa De La Piedra and George Cook of the District and Michael Maley of Kennedy/Jenks Consultants (http://www.kennedyjenks.com).

With the growing uncertainty of traditional California water supply sources, protection of the water quality of existing groundwater resources is a critical groundwater management task. As such, the primary objective of the Groundwater Vulnerability Study is to assist local resource management and planning agencies in understanding the potential impacts of future land use changes on groundwater and prioritizing monitoring and groundwater protection activities.

Groundwater Vulnerability is a combination of Groundwater Sensitivity and Potentially Contaminating Activities (PCA) Risk. Groundwater Sensitivity is defined as the relative ease with which a contaminant on or near the land surface can migrate to the aquifer of interest as a function of the intrinsic characteristics of the aquifer and vadose zone materials. Groundwater Vulnerability is defined as the relative ease with which a contaminant on or near the land surface can migrate to the aquifer of interest under a given set of land use management practices and contaminant characteristics, and incorporating groundwater sensitivity conditions.

For the groundwater sensitivity analysis, hydrogeologic factors, including depth to water, degree of aquifer confinement, recharge rates, and hydraulic conductivity, were correlated with nitrate concentrations in groundwater using logistic regression analysis to identify the factors that most influence groundwater quality. Identified factors were used to develop a groundwater sensitivity regression equation. The statistical evaluation used in this study provides a more rigorous and reliable approach compared to simple index ranking methodologies commonly used for these types of assessments, such as USEPA's DRASTIC method.

PCAs were inventoried and ranked based on their association with regulated contamination cases and other criteria. PCA risk and sensitivity were combined to characterize the relative vulnerability of the study area to contamination. The sensitivity, PCA risk, and vulnerability were mapped and a web-based GIS tool was developed to allow easy viewing of information used in the analyses, uploading of new hydrogeologic data and land use information, and re-evaluation of groundwater vulnerability due to proposed land use changes.

Todd Engineers Coauthors Groundbreaking NDMA Research Paper

The paper presents findings of a two-plus year field investigation of the fate and transport of NDMA in surface water and groundwater. Laboratory incubation work conducted by others indicates that NDMA can be biodegraded under both aerobic and anaerobic conditions. Until this study, however, direct field evidence of in situ biodegradation in groundwater has been very limited.

NDMA, an emerging contaminant in groundwater, is a byproduct of wastewater treatment processes. The County Sanitation District of Los Angeles County operates three water reclamation plants (WRP) that provide highly treated recycled water that is actively recharged at spreading grounds in the Montebello Forebay of the Central Groundwater Basin in Los Angeles County, California and incidentally recharged along upstream unlined river reaches.

For this study, NDMA was monitored in an extensive network including effluent locations, surface water stations, and groundwater monitoring and production wells to assess the fate and transport of NDMA. Monitoring results and surface water/groundwater modeling indicate that significant biodegradation of NDMA occurred in groundwater, accounting for an estimated 90 percent mass reduction over the seven-year monitoring period.

A copy of the paper can be purchased from http://www.elsevier.com/salesoffices.

Todd Engineers Completes Five-Year Review of Closed Palos Verdes Landfill

The review, with oversight from the Department of Toxic Substances Control, was conducted to determine whether groundwater protection and landfill gas containment systems are protective of the environment. The study evaluated over 300,000 data points from routine data collection events conducted between January 1987 and December 2006. The project also included considerable public outreach and involvement. As a result, multiple special studies were conducted to further evaluate issues of concern raised by the public. An updated health risk assessment was conducted by Nexus Environmental Services to evaluate the potential health risks associated with living or working at or near the Site. The study concluded first, that the environmental control systems are effective and protective of the surrounding community and the environment and second, that current recreational uses are appropriate for this Site.

The complete report can be viewed and downloaded at http://www.lacsd.org/about/solid_waste_facilities/palos_verdes/five_year_review.asp.

Presentation and Publication of Paper on Mining Impacts at Tailings and Mine Waste Conference

The paper was presented by Dr. Motzer at the Tailings and Mine Waste 12th International Conference held in Vail, Colorado, on October 20, 2008. This and other conference papers are available in the book Tailings and Mine Waste '08 published by CRC Press/Balkema-Taylor & Francis.

The paper addresses a historic underground gold mine in the Sierra Nevada of central California, which was re-opened as an open-pit surface mine and operated for several years until the ore body was mined out. A mine closure plan was submitted and accepted by regulatory agencies followed by extensive reclamation of all site features except the mill tailings pile. The mine owners developed an alternate capping plan based on performance criteria, but the revised plan was not initially accepted by the state. As a result of delays, the entire mine site was re-examined. Concerns addressed included offsite migration of dissolved metals in groundwater, stormwater sediment transport, the formation of a pit lake containing dissolved constituents, and other complex issues. Reclamation is now in progress following negotiated closure specifications.

Todd Study Cited in Court Decision on SB 610 Water Supply Assessments

For large development projects, the Water Code (section 10910, commonly referred to by its original legislation, Senate Bill 610 or SB 610) requires that water suppliers prepare a water supply assessment that determines whether water supplies are sufficient for the project and other planned growth over the long-term. If the water supply for the proposed project includes groundwater, the assessment must analyze the sufficiency of groundwater to meet the projected demand of the project.

In O.W.L. Foundation vs City of Rohnert Park, a key issue was the scope of the groundwater analysis. O.W.L. interpreted the water code to require analysis of all current and future pumping on the basis of a groundwater basin, with specific reference to groundwater basins as defined by the Department of Water Resources. The Court of Appeal rejected O.W.L.'s narrow interpretation, noting the large size of some groundwater basins and the impracticality of collection and analysis of basin-wide data in the 90-day statutory deadline for completion of a water supply assessment.

O.W.L. also argued that the study area used by Rohnert Park was inappropriate because it was based on watershed boundaries; these boundaries had been defined in large part by Todd Engineers in a 2004 study for Sonoma County, Groundwater Study for the Canon Manor West Subdivision Assessment District. However, the Court found the watershed study area to be legally adequate, indicating the Todd study not only provided an independent analysis, but also a rationale and evidentiary support including a discussion of the relationships between watershed boundaries and groundwater divides.

The Court's decision provides valuable guidance for preparation of water supply assessments and affirms that water suppliers and their experts must have discretion in selecting the study area and methodologies, as long as there is adequate empirical data and analysis.

We Wrote the New Book on Groundwater!

This new enlarged edition updates the second edition of 1980, the most widely-used book in the field with translations into six languages. The third edition adds numerous example problems, case studies, problem sets for student use, and more than 300 new figures and photographs. An entire chapter is devoted to presentation of groundwater modeling using the MODFLOW program of the U. S. Geological Survey. Groundwater contamination by chemicals receives expanded coverage, new references at the end of each chapter are given for research and graduate study, and web sites for hydrologic data and information are listed for U. S. Government and non-governmental sources.