Environmental Consulting Lessons Learned from the World of Analytical Chemistry

The story of environmental consulting projects often start with what the laboratory results tell us. However, all results are not created equal, and it’s important to know the big picture – site subsurface conditions, regulatory criteria, and chemistry principles – when uncovering culprit contaminants.

At one of Aspect’s recent, ongoing Technical Exchanges, Staff Scientist Andrew Yonkofski invited Mike Erdahl from Environmental Laboratory Friedman and Bruya to discuss the role of analytical chemistry in environmental consulting, including general petroleum chemistry, gas chromatography, and interpreting those results. Part of the discussion was focused on an Aspect-specific case study from a Seattle-area waterfront site. This site presents a unique look at how organic matter in the subsurface can affect results from the NWTPH-Dx analysis.

Lessons learned from the talk included:

  • Common petroleum hydrocarbon mixtures, such as gasoline and diesel, contain thousands of unique organic compounds. The NWTPH-Gx and NWTPH-Dx analytical methodologies attempt to capture the wide range of organic compounds found in petroleum hydrocarbon mixtures.

  • While the laboratory provides a reproduceable, quantifiable number for total petroleum hydrocarbon (TPH) results, those results often need to be interpreted in light of the chromatographic results. For instance, the higher boiling end of gasoline overlaps into the diesel-range. As the gasoline weathers, the proportion of material in the diesel range increases in relation to the total TPH value. Qualifying the diesel results as overlap from gasoline contamination can reduce the number of site-specific contaminant of concerns.

  • Likewise, results using both the NWTPH-Gx and NWTPH-Dx methodologies can sometimes include organic compounds from natural sources including degradation of organic material in the subsurface.

  • To properly characterize a site, environmental consultants must use multiple lines of evidence to determine the nature and extents of contamination. This includes interpreting analytical results and the associated chromatograms in the context of the historical site use.


This chromatogram illustrates how gasoline can overlap into the diesel-range. The diesel results reported by the lab do not indicate a separate diesel release from the gasoline release but rather illustrate how gasoline can overlap into the diesel-range as the product becomes weathered in the subsurface.

This example shows what a chromatogram may look like when there are multiple sources (both gasoline and diesel) present in a sample.

Technical Exchange: Talking Cleanup Levels

Cleanup levels are the beating heart of any environmental remediation project. They drive the approach, the cost, and the schedule for project closure. Yet, the path towards cleanup level selection is murky – one size does not fit all. In Washington State alone there are a variety of cleanup levels – set through the Model Toxics Control Act (MTCA) – and selecting the correct one for a site requires a sound understanding of site-specific data, the science of how the media at the site exists and moves, the pertinent regulatory requirements, and what, ultimately, is the site going to be redeveloped? If so, for industrial purposes? For livable space?

At a recent Technical Exchange, senior hydrogeologist Dana Cannon tackled this knotty topic in an open discussion of what we talk about when we talk about cleanup levels. Questions asked and answered included:

  • What cleanup levels apply in what situations?
  • What exposure pathways do different cleanup levels address?
  • MTCA and other ARARs: Where do cleanup levels come from, and what’s an ARAR, anyway?
  • Method A cleanup levels: when can I use these? Do I want to?
  • Method B cleanup levels: now it gets complicated.
  • Method C cleanup levels: when to I get to use these?

Three overarching points rung true throughout the discussion:

  1. Get to Know CLARC. It pays big dividends to get familiar with the Washington State Department of Ecology’s Cleanup Level and Risk Assessment (CLARC) database and MTCA.
  2. Exposure pathways. Understand the human and ecological exposure pathways for a given site. From there, cleanup level selection becomes clearer.
  3. Strategy. Strategy means knowing the site conditions backwards and forwards, knowing the end goal for the site after cleanup, and understanding which cleanup levels apply. Knowing how to approach CLARC relative to site exposure pathways puts you ahead of the game.

Matching the Quality of the Words with the Quality of the Science

Everyone at Aspect writes something. Whether it’s a short memo to a property owner, a long report to a regulator, an email to a potential client, or a web story talking about writing. We generate a lot of words, and very few of them come easy. Yet, writing is crucial—for many reasons, but primarily because the quality of our words should match the quality of the science.

In a recent technical exchange, a panel of senior staffers shared their best practices for how we convey the conclusions and recommendations we form as a result of our scientific collaboration through our writing.

Our staff can be out in the field collecting and reviewing data, devising creative ways to approach and solve problems, and doing overall stellar work. But if we can’t clearly articulate what we did and why we did it, then all of our work can be lost in translation. Taking ideas, solidifying them into a sort of outline, and then turning to blank page to try and translate all of that into words in a clear, concise fashion can be an extremely daunting task.

Indeed, each panelist admitted that writing is hard work, especially when we hold ourselves to a high standard for delivering quality results. They shared how they approach a writing assignment and tackle challenges that come up along the way. The discussion sprung from four key questions:

  • How do you start a new writing assignment?
  • What do you look for in writing from your project team?
  • What is the best advice about writing that you’ve received?
  • What is your greatest personal writing challenge?

Over the course of our talk, we learned everyone has a different way of combating the fear and angst generated from a blank page. Some meticulously outline and then fill in section by section. Some dump any and all information that may be relevant and then carve out the document from the raw material. Some schedule themselves a block of time to write and stick to it. Some avoid it until the deadline looms near. Some know the conclusion and write their way back from it, some figure out the ending as they go along. We did find some common ground among us—we all feel a little lost at the very start of a project, and we all look to existing reports to guide the way.

We left with the knowledge that though there’s not a perfect tool or exact method for filling the page, knowing what your writing process is – i.e., what works for YOU—is the most important part of writing successfully. Developing a writing style and rhythm is an ever-evolving process. 

 

Aquifer Storage and Recovery: An Innovative Approach to Water Storage

After years of work, Aspect recently finished a pilot test that will help the City of White Salmon (City) implement one of only a handful of Aquifer Storage and Recovery (ASR) systems in the state. ASR—essentially taking advantage of natural geology, man-made wells, and climate patterns to create an underground reservoir—is an attractive water supply concept. It’s relatively low-cost (compared to building an above ground reservoir), has a small environmental footprint, and in arid climates reduces losses from evaporation. However, permitting of an ASR system involves overcoming technical operational hurdles that hinge on two key questions:

  1. How much water are you getting back? (recoverability)
  2. Will injection or withdrawal affect water quality? (Washington State Department of Ecology’s (Ecology) antidegradation policy)

During Aspect’s monthly technical exchange series, Aspect’s Tim Flynn, Joe Morrice, and Jared Bean gave a presentation and explained Aspect’s experience with ASR in the state and what it means for future water supply.

Creating an Underground Reservoir

Essentially, this concept uses nature’s pre-built reservoirs (aquifers) to create an underground reservoir or tank to store water when it’s plentiful and withdraw it when it’s scarce. In water resources terminology, ASR typically uses seasonally available surface water to help recharge—or move water from the surface into the ground—an aquifer. It does this by capturing excess water during the winter and spring months, when surface water flows are generally high and water system demands low, and injecting that water via a well (or engineered infiltration basin) into the underground aquifer. During the dry summer season, water is withdrawn for use when surface water flows are low and water system demand is at its peak. 

Figure 1. ASR System Cycle
Source: www.groundwatergeek.com

The basic components of an ASR system include:

  • The right kind of Aquifer. Bedrock or unconsolidated aquifers may both be suitable for ASR, but ideally the target aquifer would be bounded by geologic faults or other barriers that limit the flow and loss of stored water in storage before it is recovered from the aquifer.
  • Source water of suitable quality. This is typically surface water from rivers or streams, but with the appropriate water quality treatment and permitting process can include stormwater runoff, remediated groundwater, reclaimed water, and industrial process water. These sources should be chemically compatible with ambient groundwater and do not contain constituents that would violate the State groundwater quality standards, including the antidegradation standard, or can be treated to meet these standards.
  • A way to put water in and to take it out. This means infrastructure for ASR source water diversion, treatment (as needed), conveyance, and injection to the subsurface through one or more wells, with subsequent pumping to recover stored water.

ASR in Washington State

Although ASR has been in practice for many years in other parts of the nation, it’s a fairly new concept to northwestern states that have typically relied on mountain snowpack as a form of water storage to provide supply during summer months. Because of Washington’s recent drought and the scarcity of water in many surface water basins, especially during summer low flows, ASR’s popularity is growing. In Washington state, there are approximately 9 projects in development. The existing policy framework for ASR in Washington state came about in the early 2000s with two developments:

  1. In 2000, the state’s expansion of the definition of “reservoir” to include “…underground geologic formation(s)… as part of an (ASR) project” (RCW 90.03.370); and
  2. In 2003, Ecology’s adoption of the ASR rule (WAC 173-157) which established standards for ASR projects, including standards related to water rights, water quality, water treatment, and geotechnical impacts.   

Aspect is currently working on three ASR projects in Washington, Arizona, and California. Our ASR projects locations in the PNW currently span western, central, and southern Washington and include both basalt (bedrock) and unconsolidated, glacial outwash host-aquifers.  

Figure 2. Groundwater Recharge Projects in Washington State
(ASR = Aquifer Storage and Recovery; SAR = Shallow Aquifer Recharge)
Source: http://www.ecy.wa.gov/programs/wr/asr/asr-home.html

City of White Salmon ASR

The City has historically relied on surface water from Buck Creek for the City’s water supply.  In 2002, the City switched to groundwater wells as their primary supply but with decreasing well yields and limited water rights along with the WA Department of Health issuing a moratorium on new connections the City is seeking new alternatives to boost their water supply. One of these alternatives is to explore the possibility of ASR.  Aspect has helped the City pursue this option by coordinating with Ecology throughout the process. After receiving an Ecology grant, and approval of the feasibility study, an AKART analysis was completed which secured Ecology approval for pilot testing.

The most recent pilot test involved the injection of 32 acre-feet of water over the span of 53 days (135 gallons per minute, or about 200,000 gallons per day).  With the current well and conveyance configuration the City can expect to inject, store and recover about 100 acre-feet per year, which provides approximately 25% of peak (summer) demand.  These numbers are with current operational constraints of a gravity fed non-continuous injection.  If the City upgrades to pressurized injection (continuous) then they can expect more than 300 acre-feet per year, or about 74 percent of peak summer demands.

Figure 3. Conceptual Hydrogeologic Model of White Salmon Project Area
Source: Aspect Consulting

One major concern is to make sure the quality of the water isn’t degraded while in ‘storage’.  The pilot test showed the formation of disinfection byproducts (DBPs) from treating the injected water with chlorine prior to injection.  Ecology’s antidegradation policy says injected water cannot impact native groundwater or source water quality. Groundwater quality monitoring throughout the pilot test showed that DBPs did form in the injection water, but quickly dissipated in the aquifer.

The other hurdle is the recoverable quantity of water or the amount of water recouped from what was originally injected, i.e., “recoverability”. Ecology requires that the same water that is stored be recovered, and any stored water that migrates past the capture zone of the recovery well is no longer available for use.  Aspect has estimated, based on water quality monitoring and aquifer hydraulic response to injection and recovery, that the White Salmon ASR system has 85% recoverability of injected water.

Aspect is engaged in ongoing discussions and interactions with Ecology’s water quality and water rights permitting programs regarding these issues and how to efficiently complete the required permitting while protecting groundwater quality and water rights, including instream flows for the City of White Salmon and other ASR projects.

The interpretation and understanding of water quality and water right permitting requirements for ASR projects is evolving as project proponents advance their plans through Ecology. Aspect will continue to work with clients across the state to use ASR as a viable option in providing water where and when it’s needed most. 

A Look Inside Vapor Intrusion

When volatile chemicals have the potential to migrate from contaminated groundwater or soil into an overlying building—i.e., vapor intrusion (VI)—a whole new layer of complexity is added to environmental remediation projects. In Washington State over the last several years, vapor intrusion has been under increasing regulatory scrutiny. An understanding of vapor intrusion typically revolves around a few core questions:

  • How to accurately evaluate it?
  • How to keep abreast of what’s required, given that the regulatory guidance is constantly evolving?
  • How to protect human health during and after site cleanup?

During Aspect’s monthly technical exchange series, Eric Marhofer, Dave Heffner, Carla Brock, Eric Geissinger, and Kirsi Longley of our environmental team gave a roundtable presentation of their collective experience at assessing vapor intrusion at well over 100 sites.

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Walking and Talking the Seawall

One way Aspect encourages cross-pollination of ideas across the company is our monthly firm-wide “Technical Exchanges”. One part deep-dive into the technical challenges that face our clients and one part team-building opportunity, these meetings give us a chance to gather and talk shop with colleagues. September’s exchange was led by Principal Geotechnical Engineer Henry Haselton, who covered the history, design, and current status of the Seattle Seawall replacement project. Prior to his position at Aspect, Henry served as the deputy Project Manager during the planning and preliminary design stages of the Seawall from 2009 to 2013. 

As the largest infrastructure project in Seattle’s history, this massive undertaking is striving to protect the “front porch” of Seattle. Henry’s presentation covered both the history of the original Seawall and the design and ongoing construction of the current one.

The original seawall was built between 1916 and 1934, mostly supported by wooden piles. This timber was all that stood between the waterfront and Puget Sound. As the years progressed, it was in increasing need of repair as sinkholes, tidal influences, waves, and marine foes like gribbles taking millions of tiny bites out of the wood took their toll. The 2001 Nisqually earthquake caused the adjacent Alaskan Way Viaduct to settle and increase pressure on the already stressed wall, thus spurring the City of Seattle to make seawall replacement a priority.

The new Seawall has a complex mix of pieces and players to coordinate: design and construction of a brand new earthquake-resistant seawall; navigating around a complicated lattice of preexisting in-water structures—including around 30,000 wood pilings—and utilities; enhancing marine habitat and environmental quality; and addressing public safety. They had to do this atop one of the busiest waterfronts in the country while managing and minimizing impact to tourism, businesses, roadways and bike/pedestrian passages—and taking into account concerns from a vocal roster of affected parties.

After Henry’s presentation, he took the Aspect crew on a walking tour to see the ongoing work. Here are a few of the project’s innovations we saw in action. 

Jet Grouting

Jet grouting is currently happening between Marion Street and Yesler Way, including the section in front of the ferry terminal. Jet grouting can effectively improve ground around obstructions like utilities, sewer outfalls, and the some 30,000 piles that are still in place from previous waterfront structures. 

Freeze Walls

Freeze walls minimize the groundwater entering the construction area by literally freezing the soil. They require a large amount of refrigeration—hence the frost that gathers around the pipes. 

Fish-Friendly Corridor

This corridor will one day be traveled by fish making their way through Elliott Bay. Young salmonids thrive in shallow waters with minimal light contrasts. The corridor will direct them into these friendlier waters separate from the deeper, darker Elliott Bay. Bumps and grooves on the inside wall are conducive to algae growth, so the fish can stop and snack during their trip. The small “speed bump” in the middle of the picture above accommodates the University Street Combined Sewer Outfall. 

Light Penetrating Surfaces

Closer to the Seattle Aquarium, the new seawall is in place and the sidewalks are already in use. These little windows in the waterfront promenade will allow sunlight to reach the young salmonids and other marine life in the fish corridor below. 

Learn more about the project's background, current status, and next steps at Waterfront Seattle.