An attorney we work with asked me to look at a phase I environmental site assessment (ESA) for his client. His client was really interested in the property, which already had a solid lease.
The ESA disclosed a historical recognized environmental concern (HREC) and a recognized environmental concern (REC). Both had to do with a release of gasoline from a former underground storage tank (UST) at the property. The property had environmental case closure with very low levels of gasoline contamination left in place.
The question posed by the attorney’s client boiled down to the Phase I recommendation - “Complete a Vapor Intrusion Assessment and Prepare a Soil Management Plan”.
“Is this necessary?” the client asked.
I told them that the recommendation was very conservative based on the information provided in the ESA. I let them know that if they planned to redevelop the property, the county would probably look to them to voluntarily investigate for vapor intrusion and prepare a soil management plan as part of the redevelopment.
I advised that the recommendation was overly conservative given their intention to hold the property as is. I also told them that it was unlikely a vapor intrusion assessment would disclose a vapor intrusion problem.
As we were wrapping up, a question came up, “What is a vapor intrusion assessment?”
I started my answer with an explanation of vapor intrusion.
As a liquid chemical evaporates, it turns from a liquid into a vapor or gas. All liquids evaporate to some extent, and the extent to which a liquid evaporates shows its volatility. The more volatile a liquid is, the more quickly it turns into vapor.
When a liquid chemical leaks into the ground, it enters the soil and groundwater. Once in groundwater, the chemical moves along with the groundwater. As this process unfolds, and depending on its volatility, some of the released chemical turns into a vapor and enters the space of dry soil above the groundwater. The vapor can leak up through the ground and enter a building causing a buildup of chemical vapors in the building. This process is vapor intrusion.
As time goes on, groundwater carries the dissolved chemical downstream from the chemical release. At the same time, a vapor plume (just like the billowing smoke that forms above a smokestack) forms in the soil above the affected groundwater. The area of the vapor plume mirrors the area of chemically-affected soil and groundwater.
A vapor intrusion assessment uses the link between the vapor plume and affected soil and groundwater to confirm whether there is contaminated soil and/or groundwater in an area, and to determine whether any detected contamination poses a human health risk due to vapor intrusion.
In practice, a vapor intrusion assessment involves collecting soil vapor samples from small wells spread across the area you are investigating, and testing the soil vapor samples for suspected contaminants.
Typically, detected contamination levels in soil vapor are used to estimate how much area is contaminated, identify areas of high contamination or “hot-spots”, and gauge potential human health risk by comparing detected levels with published environmental screening levels (ESLs).
A vapor intrusion assessment has some real advantages over the more traditional phase II soil and groundwater assessment for figuring out where soil and groundwater contamination is, where the highest levels of contamination are, and whether soil vapor intrusion poses a human health risk.
Number one, a soil vapor assessment costs much less than a soil and groundwater assessment, generates less waste, is less intrusive, and provides information that can be used to target a groundwater and soil investigation, and possible cleanup. Additionally, a soil vapor assessment can be used to examine vapor intrusion health risk.
Of course, a soil vapor assessment does not provide all the information a soil and groundwater investigation can, but it gets you well down the road and allows more efficient and cost effective phases of investigation and cleanup.
Our recommendation: Before drilling for soil and groundwater samples, use a soil vapor assessment to get a valuable overview.
In this article we took a look at soil vapor intrusion, explained what a soil vapor assessment is, and described some of the advantages a soil vapor assessment has over a traditional phase II soil and groundwater investigation.
If you have a Phase I ESA that recommends verifying a HREC or REC, go ahead and get a second opinion, and if necessary, consider using a soil vapor assessment to confirm the ESA recommendation. With over 30 years of experience in conducting soil vapor assessments and reaping its advantages, we can help. Please call us at 831-475-8141 or click below to schedule a free consultation.
Everything has a beginning, middle, and end - even groundwater monitoring.
The Beginning. After contamination is identified in groundwater at a property, it’s common practice for the local environmental oversight agency to require groundwater monitoring. In California, the response to groundwater contamination is prescribed in State Water Resources Control Board Resolution 92-49 (SWRCB 92-49). This usually comes in the form of a regulatory directive - a letter arrives in the mailbox.
The Middle. The directive usually requires investigation, cleanup, and reduction of contamination by completing the following phases under their oversight:
1. Initial site assessment
2. Soil and groundwater investigation
3. Cleanup and reduction
4. Verification monitoring
The thing is, groundwater monitoring usually begins with initial site assessment and ends with long-term verification monitoring - which may take up to 10 years to complete.
What is groundwater monitoring? In essence, it’s measuring how deep groundwater is below the ground and collecting samples of groundwater for various tests. Groundwater is reached through wells that can be temporary or permanent. The wells are built in holes drilled through the soil into the groundwater. Sometimes, no well is used and groundwater is monitored using a bare hole.
During the initial site assessment phase, groundwater monitoring is used to identify the type and general location of contamination. During investigation and cleanup, groundwater monitoring is used to observe changes in contaminated groundwater and the effects of cleanup and contamination reduction. Long-term verification monitoring is used to build confidence that contamination left in place will not cause future problems. It's easy to see how groundwater monitoring seems to go on and on.
Groundwater monitoring is done to answer the following questions:
The answers to these questions provide much of the information used to complete investigation, cleanup and reduction of contamination - and receive environmental case closure.
As more information about the groundwater contamination becomes available, groundwater monitoring becomes more focused. As a result, it might be possible to reduce monitoring costs by reducing the monitoring frequency, the number of wells monitoring, or the number of tests performed.
The End. Groundwater monitoring ends when contamination levels no longer need watching. All the questions about groundwater contamination have been answered.
Early on - the what, where and how of contaminated groundwater are answered in the preliminary and investigation phases. Contaminant cleanup and reduction continue, and after a few years the seasonal patterns of groundwater flow and contaminant levels are generally understood. Over this period, the decrease in groundwater contamination over time is well established. There comes a point where the groundwater monitoring information shows that even with groundwater contamination safely left in place, cleanup goals will be reached in a reasonable time.
Finally verification monitoring is done to record final site conditions for environmental case closure. Groundwater monitoring usually stops at this point because in most cases verification monitoring supports case closure.
Groundwater monitoring begins with a regulatory directive and ends with a regulatory directive; No Further Action - Case Closure.
We answered the question about how much groundwater monitoring it takes. We described the beginning, middle and end of groundwater monitoring, and how it follows the phases of contamination investigation, cleanup, reduction and case closure. If you’re somewhere around the beginning, middle, or end of your own groundwater monitoring experience, and need some help or a second opinion, give us a call or click the button below for a free consultation. We have over 30 years of experience in completing environmental investigation, cleanup and reduction - including groundwater monitoring.
You’re reading this because you are looking for an honest and reliable environmental consultant who will save you money, give you the answers you need, and provide reassurance. When confronted with an environmental issue, one of the most important questions you’ll have is, who are the best consultants in my area?
RRM wants to help prospective clients find the best company to meet their needs. We’ve been in business since 1992 providing cost-effective solutions to environmental challenges, and we understand the necessity for exploring other options. We compiled a list of local companies to help you narrow your search.
Here are our top picks:
Weber, Hayes, & Associates
Located in Watsonville, WHA has been providing environmental and geotechnical services since 1988. They have extensive experience providing services to the agricultural industry, including guidance on stormwater conveyance and detention, and waste discharge for composting operations.
This company operates from Monterey and offers a wide range of environmental testing and inspection services in areas such as industrial hygiene, building science, and specialty construction. Their industrial hygienist provides consulting in indoor air quality testing, indoor environmental services, and environmental analysis.
Trinity Source Group, Inc.
Established in 2005, Trinity is located in downtown Santa Cruz. They offer a broad range of environmental consulting, management, and construction services with a turn-key approach to environmental challenges. This includes providing drilling services in addition to environmental services.
Red Hills Environmental
Based in Los Gatos, RHE offers a full range of professional and technical services for the investigation, remediation, and management of difficult environmental conditions. They are great at helping people understand tricky compliance situations.
While cost is always one of the first topics you might discuss, you might also want to hear about their experience in dealing with your particular problem, about their relationship with the relveant county and state agencies involved, project timing, and what potential contract arrangements look like.
We hope this post has provided you with information that helps you make the best choice. No matter which consultant you choose, we are here to answer any questions. Click the button below to schedule a free consultation or call us today at (831) 475-8141.
I got a call from an exacerbated client who was rightly concerned about a letter from the county. “The county letter said my neighbor has finished cleanup at their dry cleaner and they were implementing active vapor intrusion mitigation, “ she told me. We were helping this client navigate the issues, concerns and requirements regarding investigation and cleanup at a property adjacent to her own. “What is active vapor intrusion mitigation and what does it mean for our property?” she asked.
“Good question,” I told her. “I know we’ve already talked about vapor intrusion as it relates to your property, but let's go over it briefly, then we can talk about active vapor intrusion mitigation."
“When we first spoke about investigation and cleanup at the dry cleaner next door, I told you there was a possibility that groundwater contaminated with tetrachloroethylene (PCE) traveled from beneath your neighbors property to below your property,” I recalled. “I told you that PCE in the groundwater could contaminate soil vapor and contaminated soil vapor could enter into the building on your property. Contaminated soil vapor traveling from an underground source into a building or building basement is vapor intrusion.”
“At the time, I let you know that soil vapor samples collected on your property showed there was no risk vapor intrusion,” I said. “If we had found there was even a potential risk of PCE-contaminated vapor entering your building, we would have recommended active vapor intrusion mitigation (VIM) to keep vapors from entering into your building and to protect occupants from exposure.”
“While cleanup has occurred next door,” I continued, “it wasn’t enough to eliminate the vapor intrusion threat posed by the remaining contamination. So, to allow safe occupancy of the building, your neighbor decided to use active VIM until cleanup goals are reached.”
“Okay, sounds reasonable,” my client said. “So what is active VIM?”
Simply put, active VIM methods create a pressure difference between air on the inside of a building and the soil vapor under a building in a way that keeps vapors out of the building. Active VIM methods tend to be more effective than passive methods, but more expensive. These methods can be used on new and existing buildings, they have a successful track record of performance, they can be applied to a wide variety of site conditions, and simple pressure gauges show they work.
VIM methods require periodic maintenance and they have long-term energy and maintenance costs. Let’s consider three active VIM methods: sub-slab depressurization, sub-membrane depressurization, and building overpressurization.
Sub-slab depressurization systems are designed to provide continuous pressure reduction beneath a building’s floor and foundation. This method is for new or existing slab-on-grade foundations. Sumps, drain tiles and block wall foundations can also be depressurized. Depressurization refers to using a fan or blower to bring the air pressure in the sub-slab venting layer down below the air pressure in the building. In this method, a blower or fan pulls contaminated vapor from the venting layer and discharges it above the roof line into the atmosphere. An air discharge permit may be necessary to allow discharge to the atmosphere.
For new construction, a vent layer made from sand or pea gravel is placed below the slab foundation. Soil vapor collection piping and a common header are installed in the vent layer to direct contaminated soil vapor to a discharge stack that ends above the roofline. The blower/fan connects the common header with the discharge stack. Regulatory guidelines suggest using a sub-slab liner above the vent layer to provide added protection if the fan fails.
For an existing slab-on-grade building, installation of a sub-slab depressurization system entails cutting holes or trenches in the building slab, removing soil and building venting pits or trenches in the space left behind. The vent pits or trenches are arranged to provide depressurization coverage over the entire building footprint. Collection pipes are installed in the pits or trenches after which they are filled with sand or pea gravel and covered with slab material. A common header connects the collection pipes with a blower or fan. Extracted soil vapor is routed to a discharge stack.
Sub-membrane depressurization operates like the sub-slab variety but refers to creating a venting layer beneath a membrane that is installed in crawl spaces over bare earth. It can be used in new and existing buildings with crawl spaces. The membrane covers the exposed dirt surface of a crawl space, creating a venting layer between the membrane and the dirt floor. The rest of the system is similar to a sub-slab depressurization system.
The edges of the foundation and any pass-through piping need to be well sealed and the membrane should be loose enough to prevent tearing. Routine inspection of the membrane is necessary to check for the seals and membrane for damage. An air discharge permit may be necessary to allow discharge to the atmosphere.
Building overpressure involves using a building’s heating, venting, and air conditioning (HVAC) systems or a new system to maintain positive pressure in a building relative to the pressure beneath the building floor. This method is typically used for commercial buildings and can be inexpensive for buildings where the HVAC system maintains a positive pressure.
We wrapped up our conversation of active VIM methods and turned to the question of how VIM might impact her property. I told my client that VIM at the neighbor’s property means her property won’t be exposed to soil vapor contamination from her neighbor’s property. I let her know that as long as VIM is underway, the state and local environmental health agencies will oversee operation, and that VIM will operate until cleanup goals for her neighbor’s property are reached. It was good news for my client.
We have over 35 years of experience providing solutions for environmental challenges including vapor intrusion mitigation. Can we help you? Please click the button below for a free consultation.
“I keep reading about how contamination levels are above the ESL, but all I really care about is closure. Instead, more samples and more talk about the ESL. I don’t know what this ESL is, but apparently I won’t get case closure until it is reached,” she said. “I’ve ignored it long enough - what is an ESL?”
“Good question,” I said. This prospective client came prepared with a tough question.
“ESL stands for Environmental Screening Level, '' I told her. “It’s the level of a chemical that signals there is a potential for harm to humans, water life, and animal life.” In the lull that followed, I added, “I know that’s a lot, so let’s start with where ESLs come from.”
Risk-based screening levels (RBSLs) were first published by the San Francisco Bay Regional Water Quality Control Board (Board) in 2000 as a way to speed up human health and environment risk assessments for contaminated sites.
Assessments were made easier by using a set of site conditions to estimate chemical levels (risk-based levels) that pose no harm and using them for comparison with levels at a contaminated site. If contaminant levels in soil, groundwater, or soil vapor were found to be below the RBSLs, then the site was considered low risk, otherwise contamination levels were judged to be a potential risk.
The scope of the RBSLs expanded, and in 2003 the Board changed the name to Environmental Screening Levels (ELSs). SInce then there have been several updates with the last in 2019.
The Board states that ESLs are not cleanup goals, however, the Board also states that for many sites ESLs are selected as cleanup goals. At minimum, the Board accepts ESLs as preliminary cleanup goals.
“Okay,” my prospective client said. “What does low-threat mean?”
In the context of ESLs, low-threat typically refers to chemical concentrations in soil, groundwater, or air that do not increase the chance of developing cancer or increase harm to humans.
For chemicals that cause cancer (carcinogen), low-threat means concentrations that result in less than one chance in a million (1 in 1,000,000) of developing cancer from lifetime exposure. For non-cancer causing chemicals, a hazard quotient is used to gauge the potential for bodily harm. The hazard quotient is a ratio that compares the estimated exposure to a chemical to the reference level of that chemical at which no harmful health effects are expected. A hazard index of 1 or more indicates the potential for harmful non-cancer health effects.
“Well, thank you,” my caller said. “ If I understand you correctly, an ESL is an okay amount of contamination that is not a threat to human health and animals. I can appreciate that.” With that we set up time to talk about her site and ended our phone call.
We took a look at environmental screening levels, or ESLs, published by the San Francisco Bay Regional Water Quality Control Board. We noted that while ESLs are not specifically contamination cleanup goals, they can be used as cleanup goals and oftentimes are. Do you have a question about environmental investigation and cleanup? We have over 30 years of experience providing environmental services. Give us a call at 831-475-8141 or click the button below for a free consultation.
In many cases, vapor intrusion mitigation is needed after investigation and cleanup at sites with difficult contaminants like tetrachloroethylene (PCE). This is because active cleanup methods may not remove all the contamination or cleanup may not be possible. In these cases vapor intrusion health risk remains. As a result, folks responsible for investigation and cleanup at site sites with difficult contaminants may be faced with a decision regarding vapor intrusion mitigation (VIM). At some sites, building occupancy is critical to maintaining business, and VIM is the only solution.
Vapor intrusion mitigation methods can be separated into two groups: passive and active. Here we take a look at three top passive VIM methods, but first let’s look at how VIM works.
Volatile chemicals like PCE, when released into soil and groundwater, create a vapor that can enter a building through entry points like cracks or holes in slabs or basement floors and walls; openings around sump pumps and elevator shafts; or where pipes and electrical wires enter the building. It is also possible for vapors to pass through concrete, which is naturally porous. This movement of vapors from underground into a building is termed vapor intrusion. The purpose of VIM is to eliminate intrusion through building entry points.
Passive VIM methods prevent chemical vapors from entering a building or reduce contaminant levels beneath a building. They tend to be cheaper than active methods. Typically, multiple passive VIM methods, like a floor seal with a sub-barrier, are used at the same time to provide a backup in case one of the VIM methods loses efficiency or fails. Three top passive VIM methods are: sealing, vapor barriers, and passive venting.
Sealing entry points with a chemically resistant sealer is an important first step in VIM for existing buildings. Chemically resistant coatings can also be used to seal the floor, wall and entry points in an existing building and prevent vapor entry. Concrete can be poured on unfinished dirt floors to prevent entry.
Regulatory guidance suggests that in most cases sealing should be used with other VIM methods to provide a backup.
Vapor barriers (also called sub-slab liners or passive membranes) are materials or systems installed below a building floor to block the entry of vapors. Most barriers use sheets of “geomembrane” or heavy-duty plastic placed between the sub-base and building floor to prevent vapor entry. Vapor barriers are best installed during building construction, but can be installed in existing buildings that have a crawl space or basement.
In principle, vapor barriers cause soil vapor to move laterally beyond a building footprint instead of into a building. In practice, vapor barriers are not able to completely eliminate vapor intrusion due to the likelihood of punctures, perforations, tears, and incomplete seals. As a result, regulatory guidance suggests vapor barriers be used in combination with passive venting or sub-slab depressurization (active mitigation).
Passive venting involves installing a venting layer beneath a building to provide a pathway for soil vapor to move from below ground toward the sides of the building where it is vented outdoors. The system is designed to reduce or dilute subfloor contaminant levels. A venting layer can be included in new construction, but may be too expensive for an existing building. Passive venting is usually paired with a vapor barrier.
Passive venting systems typically consist of a layer of venting material (sand or pea gravel) emplaced below a floor slab to allow soil gas to move laterally under natural dilution or pressure difference. Soil vapor entering the venting layer is directed to the edge of the floor foundation by perforated pipes installed in the venting layer, either beneath the slab or at the periphery of the building foundation.
The vent piping usually comes together at a header pipe which runs vertically up the building wall and discharges above the roofline. Installation of a vertical inlet pipe that connects the vent layer with outside air and allows fresh air to enter the venting layer can help dilute chemical concentrations.
Regulatory guidance suggests constructing a passive venting system in a way that allows the system to become an active venting system with minimum effort if necessary (use of a fan or pump to move soil vapor from the venting layer to the header for discharge). Passive venting may not be appropriate in areas with a high groundwater table or surface water drainage problems because the venting layer will not work properly if saturated with water.
Finally, since the passive venting system discharges to air, it may need an air discharge permit to comply with applicable state or local air quality discharge regulations.
Sealing is appropriate for existing buildings and can be included into the design and construction of new buildings; however, in either case guidance suggests sealing be used with a barrier, passive venting, or sub-slab depressurization (as the name implies, used for slab-on-grade building construction). While sealing is applicable to new and existing buildings, it is not recommended as a stand alone VIM solution.
When it comes to a vapor barrier or passive venting, installation in an existing building without a crawl space could be difficult and would likely require the floor to be removed and replaced. Removing and replacing a building floor, even if possible, would be expensive. As a general rule, VIM for an existing slab-on-grade building is restricted to sub-slab depressurization, an active VIM method. Sealing, vapor barrier, or passive venting are appropriate for new construction and existing buildings with a crawl space, basement, or raised floor.
It is recommended that sealing or use of a vapor barrier include passive venting to counter the likelihood of leaks, punctures, perforations, tears, and incomplete seals. Sealing is already common practice in building construction and maintenance, so it is given that any existing or new construction is or should be sealed or re-sealed. This means in practice, most passive VIM systems will employ a vapor barrier and passive venting.
We took a look at three top passive VIM methods, but there are others. For example, in the case of new construction, installation of a building with a raised floor might be the best passive VIM method. A raised-floor design includes an open first floor or other well ventilated first floor design to interrupt vapor intrusion from entering the second story living/working space.
Another passive VIM method is termed “Institutional Control”. Institutional controls typically use institutions (state, county or city government) to monitor and enforce property use controls through a land use covenant (LUC) or Covenant to Restrict Use of Property. The LUC may include multiple institutional controls with specific orders, prohibitions, restrictions and requirements to ensure property conditions under control remain unchanged and the risks, restrictions, and requirements to future buyers and occupants are disclosed.
An LUC may contain:
For a LUC with California’s Department of Toxic Substances Control (DTSC), the LUC must be approved by DTSC legal counsel and publicly recorded in the county recorder’s office.
All VIM methods mentioned require some sort of performance monitoring, so it is important to consider long-term responsibilities. For example, while passive venting avoids the long term cost to operate a fan or blower, it requires monitoring effectiveness by measuring chemical levels in sub-slab soil vapor or by measuring indoor levels. Similarly, use of sealing or a vapor barrier would require indoor air and sub-slab soil vapor sampling to monitor effectiveness.
To address the long-term nature of VIM, and the need to assure they work, regulatory oversight agencies typically expect VIM implementation to include a plan outlining operation and maintenance, monitoring, reporting, financial assurance, an implementation schedule, five-year review schedule, and identification of who is responsible for the work.
We took a look at three top passive vapor intrusion mitigation methods. We found that for most cases, passive venting is the top passive VIM method, and that passive venting is used with sealing or a vapor barrier to provide eSxtra protection from vapor intrusion. We noted that in most cases, passive VIM is only applicable for new building construction or buildings with a crawl space, basement, or raised floor. We also noted that implementation of VIM requires long-term operation, maintenance, and monitoring to show effectiveness over the life of VIM.
Due to the toughness of some contaminants like PCE, cleanup limitations, and site constraints, complete cleanup to regulatory-approved levels is not often possible. In many cases VIM is relied on to keep a building safe and occupied during the span between active cleanup and low-threat case closure.
If your site is facing VIM, we can help. We have over 30 years of experience in solving environmental problems including VIM. To get more information, call 831-475-8141 or click on the button for a free consultation.
A close friend called. She told me she was working on a development project, and just got the results of a Phase I Environmental Assessment. The assessment pointed to a potential obstacle to the project - a Recognized Environmental Condition (REC). The project site used to be a dry cleaner that closed up shop a few years back, and the assessment noted there could have been a release of tetrachloroethylene, or perchloroethylene (PCE) into the soil and groundwater. My friend was really upset. It was already difficult enough with stakeholders, banks, city and county regulators taking chunks of her time and money - now this. She was stressed. “Can you help?” she said, “Now they want a Phase II Assessment to investigate the REC. All I want to know is, how much is this going to cost?”
I paused for a moment thinking, “it depends…”, but quickly remembered the stress she was under. “How about we meet for coffee in a couple of hours and in the meantime, I will work up a cost for a Phase II Assessment for you?” That’s what she wanted to hear.
A Phase II Assessment is often recommended to verify a REC (Recognized Environmental Condition). In the case of my friend, a Phase II was recommended to determine whether there was a release of PCE. Typically, a Phase II entails collecting soil and/or groundwater samples and analyzing the samples for particular chemicals. Often, a Phase II Assessment means the same thing as a soil and groundwater investigation.
My friend described the site as a small empty retail unit at a shopping mall, so it seemed to me that we could find out if there had been a chemical leak by drilling three small-diameter holes into the ground to collect soil and groundwater samples. One at the former location of the dry-cleaning machine, one at the floor drain, and one along the sewer leaving the unit. At least two soil samples and one groundwater sample would be collected from each hole, and samples would be analyzed at a state-certified laboratory. A soil and groundwater investigation report would be prepared that would include methods, results, conclusions, and recommendations. All the work would be overseen by a professional geologist or engineer whose signature would appear on the final report.
One way to estimate the cost of work is to break it up into tasks, and then estimate the cost of each task. A Phase II soil and groundwater investigation can be broken into three main tasks: preparation of a work plan, field work, and reporting.
With tasks identified, we can estimate the cost. My knowledge and experience are important here, but a reference carries weight. The California Underground Storage Tank Cleanup Fund, a state program for underground storage tank owners and operators that funds investigation and cleanup, publishes cost recommendations (Guidelines). While these recommendations are associated with work on sites contaminated with gasoline and the like, they can be applied to assessment work for other compounds, such as the dry-cleaning chemicals my friend was worried about.
The work plan identifies known property conditions, potential contaminants and suggests how best to take samples. The Guidelines estimate the 2018 cost of a Phase II soil and groundwater investigation work plan at $3,380.
Adjusting for inflation, about 8.6% according to California Consumer Price Index (CPI) Inflation calculator, we have estimated the cost of a Phase II soil and groundwater work plan at $3,671. (Note – you can also adjust estimated costs to a particular area of California or to a national average.)
For field work, we will consider the cost of drilling three holes to 30 feet as suggested in the Guidelines. In the description of work, the Guidelines include scheduling, coordination, field preparation, permitting and field work in the estimated cost for three holes. The Guidelines also include costs for equipment rental and supplies, a drilling contractor, chemical analyses, and subcontractor mark-up. Here the number of samples and methods of sampling that the Guidelines recommend differ slightly from the proposed work for my friend’s site. To address the differences, we will simply adjust the Guidelines cost by subtracting unnecessary costs.
As presented in the Guidelines, the total cost to drill three holes to 30 feet is $11,244, but after adjusting for the difference in the number of samples to be analyzed (9 for my friend versus 15 in the guidelines) and the number of analyses to be conducted (one for my friend versus two in the guidelines), the total cost for drilling three holes to 30 feet comes down to $8,308.
Field work also includes health and safety coordination and waste disposal. The Guidelines estimate the cost of a Community Health and Safety Plan at $1,392 and waste disposal at $145 per 55-gallon drum of soil waste. It is likely only one drum of waste will be generated during field work on my friend’s project.
Regarding an assessment report, the Guidelines provide the cost for a report where six holes are drilled and three of the holes are converted to groundwater monitoring wells. It’s clear the scope of work linked to the Guidelines estimate is greater than for my friend; however, in my experience the difference in terms of report preparation is small, in this case less than $500. The Guidelines quote $6,944 for an investigation report – let’s say $6,500 for our report.
Finally, is there anything we left out? For example, it’s likely the floor of the unit is concrete, and we will need a concrete driller to actually get underground. Additionally, now that we have holes in the floor, we will need to restore the floor by backfilling the holes and patching the surface. The Guidelines are not much help here, but in my experience a concrete cutting contractor is going to cost about $500 and the backfill and patch is going to cost about $900.
Now, what else did we miss? Something. To address this something, we use a contingency factor, say 10 percent. This additional 10 percent is to account for things we did not address or for unforeseen circumstances – like the concrete floor is 15 inches thick instead of the typical 6-to-8-inch thickness.
Now we are ready to sum up the costs. Between the work plan, field work, and the report, the total estimated cost (adjusted for inflation) is $22,946. With a 10% contingency the total cost ranges from $22,946 to $25,241. Now I was ready for a cup of coffee with my friend.
I arrived on time to find my friend seated at a window table. She looked up and noticed me, “Hi, great to see you”, she said. We received our coffee and spent what seemed like forever adding cream and sugar in silence. I spouted up, “Ready for the news?” She slumped, “Okay.”
I started into my explanation of how I got the estimate, but when I looked over, her glazed eyes told me to get on with it. “Alright, I estimated the cost for a Phase II soil and groundwater investigation at your location to be $25,000.” The glaze turned intense, “That’s a heck of a lot of money - why does it cost so much?” I thought for a moment and said, “Let’s look at the factors that drive cost.”
There are several factors that drive the cost of a soil and groundwater investigation, but for me two factors top the list: the type of contamination and site location. The type of contamination can be broken down into the composition (what’s in it), the magnitude (how much is there), and the extent (how far has it spread). Site location includes things like where the site is located, how big it is and whether improvements have been done, the location of groundwater, site geology, local regulations, site use (residential or commercial); and how hard it is to properly dispose of waste from drilling. Let’s take a closer look at some of these factors.
|Factor That Drives Cost||How/Why Factor Drives Cost|
|Kind of Contamination||
Hazardous contaminats, such as those that are toxic, require specialized personnel,
|Contamination Level||Higher levels of contamination drive up waste disposal fees, and require specialized methods, personnel and equipment that cost more.|
|Contamination Area and Depth||Larger areas and depths of contamination need more time to investigate and bring on more waste to dispose of, more samples to analyze, and more data to report.|
|Soil and Rock||Very hard or dense ground requires special equipment for drilling and longer drilling times that drive up cost. The same is true for drilling in sandy or loose soil.|
|Groundwater||Dealing with groundwater drives up cost and the depth of groundwater below the ground drives cost becase greater depths require more drilling, more well construction time, and more waste disposal.|
"Well, that sounds complicated," she said. “So you’re saying that if the groundwater was deeper at my place, a soil and groundwater investigation would cost more?” “Yes”, I said, “for one thing, the field investigation might take longer than it would otherwise, increasing the cost.”
“So it could be worse…” she said flatly.
We sat in silence for a moment and then I asked if she had any more questions. She sat up straight and said, “Probably, but thank you. I need to let this soak in.” “No problem”, I replied, “let me know if you need any more help with your project.” I let her know our firm was a one-stop-shop that could provide all the environmental related services she would need to complete her project. I also told her we are very sensitive to the hardships, both financial and emotional, that environmental issues bring.
We covered a lot of ground here. Using cost guidelines from California’s Underground Storage Tank Cleanup Fund as a reference, we broke down how much it costs to complete a Phase II soil and groundwater investigation, including the work plan, field work, report, and a 10% contingency. We also looked at the two primary factors that make a Phase II so expensive - type of contamination and site location.
Are you staring down the barrel of a Phase II Assessment, and don’t understand why? Are you having trouble juggling the competing demands of regulators and other stakeholders? Let us help. We’ve got 20 years of experience solving problems just like this. Schedule a consultation by clicking the button below, or just give us a call at 831-475-8141.
We got a phone call from a concerned citizen. She was concerned because the county environmental health agency sent a letter stating vapor intrusion could be occurring at her property. “Before I talk to anybody at county health, I want to know what vapor intrusion is and what it means for my family,” she confessed.
“If you have a moment, I’ll explain,” I said. “Let’s start with the vapor.”
I’m sure you’ve seen gasoline evaporate off the pavement, or a bowl of water evaporate leaving salt rings behind. How about rubbing alcohol? You might have noticed how it quickly evaporates leaving your skin cold. When you think about it, you might have noticed how gasoline or rubbing alcohol evaporates much faster than water. What’s going on?
When a liquid chemical evaporates, it turns from a liquid into a vapor or gas. All liquid chemicals evaporate to some extent, and the extent to which a chemical liquid evaporates shows its volatility. The more volatile a chemical liquid is, the greater the tendency it has to generate a vapor. Gasoline has a greater tendency to turn into vapor than water, that’s why gasoline evaporates off the driveway faster than water, and that’s why gasoline is more volatile than water.
When a liquid chemical leaks into the ground, it enters the soil and groundwater. Once in groundwater, the chemical has the potential to move along with the groundwater. As this process unfolds, and depending on its volatility, some of the released chemical turns into a vapor and enters the space of dry soil between the groundwater surface and the ground surface. At the ground surface, the vapor can enter buildings causing a buildup of chemical vapors.
Vapors primarily enter through openings in the building foundation or basement walls such as cracks in the concrete slab, gaps around utility lines, and sumps. It also is possible for vapors to pass through concrete, which is naturally porous. In their vapor form, contaminants like gasoline, tetrachloroethylene (PCE), and other volatile organic compounds (VOCs) can be inhaled, thereby posing immediate or long-term health risks.
After explaining what a vapor is and what intrusion is all about, we got back to the subject of the county letter. I explained, “The letter is warning you that a groundwater plume contaminated with PCE may have moved under your property and the PCE vapor from the plume may be causing a vapor intrusion health risk.”
“The letter goes on to request you contact the county office so they can arrange sampling soil vapor at your property and determine if there is a health risk,” I finished.
“So what if they find contaminated vapor beneath my property?” she asked.
I told her it depends on the level of contamination. At low levels, only monitoring may be necessary to show vapor intrusion is not a threat over time. At moderate to high levels, contaminant cleanup and/or mitigation might be required to eliminate a vapor intrusion health risk.
“I have one more question,” she said. “Who’s going to pay for all this? It wasn’t our fault the contaminated groundwater moved under our property.”
I sympathized and explained that there are various grant and funding programs in California for this situation. “I am sure that if the county finds contamination, they will look to those responsible for the contamination, and if they can’t find those responsible, they will use the appropriate funding mechanisms available from the state.”
We took a look at what vapor intrusion is and how it could affect anyone near a contaminant release, even if the release didn’t happen on your property. The next question is how to protect yourself from vapor intrusion. Check this space for some answers.
We have over 30 years of experience dealing with problems like vapor intrusion, cleanup, and mitigation. If you have similar problems, we may be able to help. Click on the button below for a free consultation and learn more about what we can do to help.
“I just received an alarming letter from my county environmental health department that our property well is near a site where contamination was recently discovered. Our well is our primary source for drinking water. What do we do? Should we be worried?”
First, try not to panic. We realize this can be concerning news, especially when the letter does not provide helpful information, or the language is overly technical and hard to understand. In most cases, private, domestic wells that serve a residential property are often installed to depths much deeper than the source of contamination and draw from a different underground water source (aquifer). To better understand this concept, which can feel abstract since we can’t see underground, let’s look at the graphic below which illustrates what this scenario might look like.
An aquitard is a layer of bedrock or other impermeable material that separates different aquifer zones. In most cases, an aquitard will prevent mixing between shallow and deeper aquifers. If the contamination affects the shallow aquifer, and a nearby well is drawing from a deeper aquifer, it’s not likely the same contamination will be found in the deeper aquifer because it’s separated by the barrier of the aquitard.
This graphic is only a generalized view, but it can put into perspective what might be the case for your well. To understand the situation more fully and what it means for your water source, you’ll want to review the installation records for your well. Once you have that information, you can compare your well with the depth of the contamination that was discovered. If you don’t have information on your well and don’t know the depth, the Department of Water Resources (DWR) may have a record of your well in their database. It’s state law that geologic logs and pertinent information on all wells drilled in California be provided to DWR.
Here are Your Next Steps:
1. Find your well information and review the design specifics.
2. Prepare a list of questions - here are some suggestions:
3. Call the person at the environmental health department who sent the letter for more information.
4. Call an environmental cleanup agency or consultant for an independent assessment of the situation.
When a site has been identified as a source of contamination, one of the first requirements from the oversight agency handling the case is to conduct a well survey, which is a tool to identify all the wells within a given radius from the source (usually ½ mile). The caseworker will analyze the survey and identify which wells could be affected by the contamination based on their construction and the distance from the source. The next step is usually obtaining permission from the well owners who could be affected to test the water from their well.
Right now we are consulting for a property owner who had a small farm in the family. Underground storage tanks (USTs) were used at the farm for fueling equipment and vehicles. Although the USTs were removed in the 1980s, they leaked, and fuel was released into the surrounding soil and groundwater. A neighbor who lives in a house next door draws water from a private well on their property and is within proximity to the source of contamination. Although their well is constructed to draw water from a deep zone at 300 feet, their well has a screen that extends through the shallower aquifer where contaminants have been discovered in groundwater samples. We’ve tested samples from the well at least twice per year since 2007, and none of those samples showed traces of contaminants. It is the responsibility of the land owner or responsible person of the contaminated site to provide for testing, and relay the results to the well owner.
It can be daunting to receive a letter with such alarming news, but arming yourself with information and asking the right questions will go a long way toward helping you feel safe about the integrity of your water. We have over 40 years of experience dealing with government agencies and cleaning up environmental messes - we can help you. Give us a call at (831) 475-8141 or click the link below for a free consultation.
A small water district in the Central Coast Mountains, received a letter of noncompliance from Santa Cruz County Department of Health because of concerns with the surface water treatment system and disinfection system. We provided internal and external support to the water district, including meeting with the oversight agency representative to address the concerns. To the extent possible, we enabled the district, thereby limiting their cost for compliance. As part of our services, we developed a compliance plan, identified equipment vendors, developed engineering estimates, and helped the district in decision-making. In another case, we designed a slow sand water treatment system to provide drinking water for a small number of connections. The water supply emanated from a water diversion on a small creek. Design of a slow sand filter was proposed because it could operate remotely without electrical power and is an approved filtration technology according to Title 22 of the California Code of Regulations.