Palo Alto company tackles toxic plumes

New application by Terradex maps out contaminated sites, cleanup efforts

Palo Alto resident Bob Wenzlau may be best known locally as the pioneer of the city's curbside recycling program and a leading advocate for a new compost facility, but in recent months he and his company, Terradex, shifted their focus to a different type of waste: the contaminants buried under industrial sites throughout Silicon Valley.

The murky and complex topic of groundwater contamination has been a hot one in cities like Palo Alto, where a toxic plume under what is known as the "Hewlett Packard-Varian site" in the Stanford Research Park raises perpetual concerns about new developments. And in Mountain View, contamination has been found under an industrial site around North Whisman Road, a legacy left by computer companies that occupied the site in the 1970s. Groundwater in both cities contain trichloroethylene (TCE), a chemical that has been deemed a carcinogen by the Environmental Protection Agency.

Though regulatory agencies have long detailed the potential harm of TCE, including neurological and reproductive, the information about specific Silicon Valley cities isn't easy for a layman to find. Data about these underground contaminants are dispersed throughout dozens of different databases, Wenzlau said, making it difficult for city officials and residents to access and understand the information. This, in turn, makes it hard for cleanup efforts to generate momentum.

To remedy the situation, Terradex created a Web application that consolidates all the information for each Superfund site in the Silicon Valley, as well as for dozens of other contaminated areas. It maps out each toxic plume, provides information about the chemicals and links to pertinent reports from government agencies. Also, rather than illustrating the contamination sites' single points, the company's map stretches them into polygons to give viewers a better idea of each plume's reach.

The application, known as CleanDeck 2.0 and available on the company's site, also provides information about status of the cleanup at each area; maps out areas where environmental protections have been implemented; and illustrates where land-use restrictions exist because of the contamination. It also maps out "sensitive uses" such as schools and day care centers so that users can see the proximity of these amenities to the toxic plumes.

In a January blog post announcing the new application, Wenzlau noted that hundreds of groundwater plumes exist across Silicon Valley, and "many contain volatile chemicals that could migrate upwards to occupied structures and then be inhaled by occupants."

"Over the past 30 years, industry has transformed to new office parks hosting businesses like Google and Facebook," the post stated. "The workforce is smart, growing and young -- but also vulnerable to carcinogenic vapors from shallow contaminated groundwater plumes from legacy businesses."

Wenzlau said he was partially inspired to pursue this project by the fact that his daughter works around Santana Row in San Jose, near another contaminated site. Also, he has friends who work at Google and who may benefit from knowing about harmful contaminants buried underneath the company's campus. The goal, he said, is to make the information clear and easily available.

"I think that too much of the environmental data is designed for environment scientists, not for the public," Wenzlau told the Weekly. "I also believe that once people know more about these hidden toxics, the cleanup process and the oversight process would be strengthened and speeded up. Because these plumes, they have been here for 35 years and at the pace they're going, they'll be here for another 50 years."

The new application is a starting point for what Wenzlau hopes will evolve into a broader effort to bring residents, employers, workers and environmental experts together in a network focused on cleaning up the contamination. Each site on Cleanup Deck 2.0 includes links to Facebook, Google+, Twitter and LinkedIn, and the goal is to create a system through which residents can comment on sites and offer input on ongoing cleanup efforts.

The hope is that the software will create a Yelp of sorts for contaminated sites, with people observing, commenting and updating each other about particular sites. At the same time, he hopes city planners in places like Mountain View and Palo Alto, where his company is based, will use the application. The maps, he said, help illustrate the magnitude of the challenge faced by local, state and federal officials charged with cleaning up the toxins.

"It reveals how unprotected we are because the environmental protections are so much proportionally smaller than the area of impact," Wenzlau said.

Ultimately, the goal is to expand the program from merely illustrating the problem to providing solutions for individuals in impacted areas. As the application evolves, Wenzlau said the company plans to add features that would connect residents and companies with laboratories that can test homes for vapors or help install controls above the plumes to limit exposure.

"By putting together this concept, we're hoping we'll be part of the value circle that offers some testing or helps offer controls through partners that we're working with," Wenzlau said.

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Like this comment
Posted by Joe
a resident of Another Palo Alto neighborhood
on May 9, 2014 at 9:15 am

It’s difficult to be too critical of people, and companies, that are trying to “do the right thing” .. but it’s difficult to see how this application is all that helpful to the average person, or even government officials, for that matter.

We’ve been living with this issue of toxics in the Santa Clara County for decades now—and it’s hard to find much in the way of evidence that there has been damage done to the environment that has subsequently harmed human, or other animal, life. Have there been any clusters of cancer, or other kinds of maladies that can be related to the ground water that has been contaminated over the years? Occasionally there are some test cases that make it to court alleging cancer, or some such, from contaminated working environments. But few of those cases have been proven.

The fact that there are still plumes of toxic materials under the ground is not news. The question of whether the water is making its way towards the surface of the ground, and possibly into our living and working spaces, is a question that this application might address—based on the delay in data being made available in the databases used by the App.

Like so many things involving multiple government agencies—the data reporting is often inconsistent, and there doesn’t seem to be a single point of monitoring that has a mandate of advocacy for the public at large.

It’s difficult to tell from this article exactly what this App does, and doesn’t do—but if it doesn’t have the ability to warn people that well water in their neighborhood might be toxic, or dangerous, or to provide some detailed data about any evidences of toxics-induced medical cases that are local to people’s homes—then it’s a little difficult to get excited about this App.

We’d like to believe that local authorities are monitoring the data that is relevant to their jurisdictions. Can the App tell us if our local governments are doing the job we think they are?

What’s also no clear is how is the parent company making any money from this App. If they are going to end up looking for a government subsidy—well, then they really need to be delivering something that the public can use, not something that draws a few colored maps.

Like this comment
Posted by
a resident of Crescent Park
on May 9, 2014 at 1:08 pm

Thank you for the thoughtful comments - and I share many of your observations. The application we are launching is called - WhatsDown.

Some of the objectives include:
- Working to explain the terminology of environmental contamination so folks can understand the ramifications.
- Make connections to health information so folks can tie the hazard to their health.
- Build a social media component so that users can engage and discuss. I have thought of Yelp! to mimic, but want to replace the restaurant with the environment.
- Organize ultimately the responsible parties and government agencies to engage with the dialogue we hope ensues.
- Reveal where protections are in place, and by default where they are not.

We have catalogued 500,000 locations and hold an aspiration to extend the catalogue from the US. What is unique is our effort to take what typically are maps of dots, and reveal that areas of groundwater impact are better represented by drawn boundaries. We also are first to show the concept of environmental protections so one can understand what measures are in place (if any) when residual contamination persists. Broadly we are moving the ball forward, but have not rolled over any goal lines.

We plan a few ways to monetize WhatsDown, but now we are just getting going. We will offer do-it-yourself testing to see if an occupied building over a toxic plume is impacted by vapors, we will generate simple reports that a realtor might use in representations, we are finding partners interested in working to extend mitigation solutions, and we may offer advertising. With that we can pay for the growth and perfection of the content and services.

I am worried that this article came a bit soon while we are still getting some kinks out of the application. We aren't hard to find, and if you have more feedback, just reach out to me directly -- or join me Monday night as we debate the future of composting in Palo Alto.

Like this comment
Posted by Kevin
a resident of Midtown
on May 9, 2014 at 3:13 pm

Watch out for alarmist scams. There is a lot of federal money spent on superfund sites, and there are always those out there who want to tap that money directly or indirectly.

Like this comment
Posted by JSL
a resident of Professorville
on May 9, 2014 at 7:51 pm

Thank you for these efforts. We are relocating to the area from Denver and I have spent the last 5 months triangulating data from various sources to find a safe place for our family to live. I look forward to exploring the app to see how it compares to my work, and learning how it could have saved me time throughout the various phases of work: discovering the issue, data gathering, and finding possible places to live.

I am an active user here in Denver and would suggest reaching out to that company as well. Neighborhood "health and safety" is always a productive and appreciated area of conversation.

Many Thanks!

Like this comment
Posted by 55 Year Resident
a resident of Old Palo Alto
on May 9, 2014 at 9:14 pm

I believe information on contaminated groundwater and soil sites (location, status of cleanup, and type of contaminants founds) can be found on the California Regional Water Quality Board's website. You can find everything from Superfund sites to the status of old underground storage tanks (UST's).

Web Link

You can find maps like these on the site (Sunnyvale):

Web Link

Like this comment
Posted by
a resident of Crescent Park
on May 10, 2014 at 9:04 am

To a 55 Year Old Resident,

You are correct that some of this information can be found at the California Regional Water Quality Board's website. Our state has one of the best maps in country. The state's mapping falls short as we shift to confronting spills that will persist perpetually under towns like ours.

We sought to address the shortcomings in WhatsDown. Web Link

One shortcoming is mapping spill sites as a point. A spill is not a point but a affects an area - a square parcel of a former gas station or many blocks underlain by chemically contaminated groundwater. The WhatsDown map shows the areal impact of contaminants.

A second shortcoming is their maps do not show environmental protections. The protections are critical to long term management of the toxics. Interns from Palo Alto High and Stanford filtered through reports to map any environmental protections associated with cleanups. Without this mapping, it is unlikely planning departments would discover the land use limitations embedded in these protections, and developments proceed blind to the impact.

We also extend the mapping beyond California to the country with an aspiration for a global map. In many areas - like tribal lands and many states, there is no mapping system like the California Water Boards. In WhatsDown visit New Jersey which lacks this style of mapping, or visit the City of Morro Bay to see munitions left behind. This information is missing from agency mapping.

We will allow the discovery of this important environmental health information for free to the public user. Social entrepreneurship is a hard work. A monetization strategy will be established, and our user community will be informed and guided to avoid hidden environmental toxics.

From a 58 year old resident,


Like this comment
Posted by resident
a resident of Another Palo Alto neighborhood
on May 11, 2014 at 7:41 am

A key policy question is what is the impact of dewatering of sites for
basement and below grade parking garages in Palo Alto? A single residential
lot can involve the pumping out of 6-8 million gallons of water. Palo Alto
allows dewatering as a property right essentially despite the entire set of environmental and developmental issues involved beyond toxic concerns.

Like this comment
Posted by resident 1
a resident of Adobe-Meadow
on May 11, 2014 at 8:20 am

For information only - Moffett Field is a super fund site and has a number of city and government agencies working on the clean-up. Contamination is leaking into the water system into the near-by housing and commercial area. The EPA is conducting community meetings on this topic. Contamination is working its way through the sewer system under the city. You should be able to review this through the city of Mountain View home pages. This problem is next door to Palo Alto. The federal government, state government, and regional agencies are participating in this activity through funding and representative participation in the clean-up activities.

Like this comment
Posted by Jack
a resident of Midtown
on May 11, 2014 at 8:26 am

A basic question that I have: When one considers all the energy used for drilling and pumping, is the CO2 contamination worse than simply allowing natural bioremediation of underground toxics to slowly clean them up? For example, has anyone done the calculation about how many grams of TCE are removed for one ton of atmospheric CO2?

Like this comment
Posted by BL
a resident of Barron Park
on May 11, 2014 at 8:52 am

BL is a registered user.

I just went to the WhatsDown website and searched a specific address. It provides a lot of information that might take longer to find without this website. I appreciate all the effort this website does in helping people research the issues that might affect their health within their neighborhood.

Like this comment
Posted by
a resident of Crescent Park
on May 11, 2014 at 7:34 pm


There are two parts - 1) the cleanup and 2) the protection. Too much attention has been on the cleanup, and not enough on protection.

Tremendous economic and natural resources are expended on cleanup, and we are now realizing the in many cases the cleanup cannot achieve goal of unrestricted use or pristine water resources. A cleanup might require removing 99.999% of the chemicals, and each decimal point might take 100 times the effort of the first decimal point. The effort produces diminishing returns, and health/environmental benefit is elusive.

Professionally I have campaigned for greater emphasis on protection or protectiveness. An interest in protection should begin sooner in the spill assessment process. An over emphasis is placed on investigating while protection is under estimated. An example of protection is making sure that vapor intrusion from plumes is not migrating into basements. My criticism has been that "protection" has too often been the tale-of-the-dog, only formalized after parties realize a cleanup fell short. In my world, protection would lead the effort, and then provide greater comfort to know that slow cleanups can be tolerated.

The formal device of long-term protection is an "institutional control" that often takes the form of an environmental easement. Palo Alto has several of them - shown in WhatsDown as yellow areas - and shown as Environmental Protections. The institutional control formalizes limits on land use. When occupied buildings are located above plumes, often liners are put to prevent vapor intrusion. As these are installed, WhatsDown will catalog them.

In a round about way, if we have protectiveness, the we can balance the resource impacts of a cleanup knowing that a discussion becomes more reasonable as folks are protected. Parties that opt to leave contamination can then support efforts to assure protectiveness.

This discussion will take more maturing overtime, but the attention we are enjoying with our efforts in this application is inspiring.


Like this comment
Posted by 55 YR Resident
a resident of Old Palo Alto
on May 11, 2014 at 9:18 pm

Some plants and trees have proven to help degrade and control the movement of plumes from certain contaminants in a process called phytoremediation.
Phytoremediation has been used in conjunction with high volume vapor strippers (pump and treat) and/or chemical remediation (dumping chemicals into the ground which react through the oxidation (or reduction) of certain volatiles in groundwater.

Phytoremediation is the least expensive energy saving way to clean up contamination. Of course, the best thing would be not spill any contaminants since it is nearly impossible to return an area back to it's original (pre-contaminated) condition IMHO.

Like this comment
Posted by Mr.Recycle
a resident of Duveneck/St. Francis
on May 12, 2014 at 2:34 am

@Bob - I see you have good intentions here, but your map does have bad data. I clicked a few pins in residential neighborhoods where I wouldn't expect toxic spills, and several were incorrect. Here are just a couple examples:

There is a pin for Intevac/EO Sensors Inc. at 601 California Avenue. Your map is putting the pin on N. California by Middlefield. It should by S. California by El Camino.

You have a pin over on Elsinore Drive by Louis Rd. The actual address for that pin is Chromalloy San Diego, 1071 Industrial Place, El Cajon, CA.

If you are going to publish this data, you have a responsibility to make sure it is reasonably accurate. Based on the number of errors, it looks like a quick cut and paste job, without review. Be careful you don't affect someone's home sale and get sued.

There are many pins that don't have an address listed, just "private residence", but they are pinned on people's houses in your map. I'm not sure how accurate those pin placements are...

Like this comment
Posted by
a resident of Crescent Park
on May 12, 2014 at 7:54 am

Mr. Recycle,

Thanks for the observation on data quality, and that there are errors.

We have an interesting duty with the map as the data we show is copied from what the various states release (google GeoTracker or Envirostor in California). The state located the sites incorrectly. For example, we enjoyed seeing that the state located the Palo Alto Landfill at the Main Library - we took the liberty to correct that.

Should we honor incorrect data that the state shows, or should we correct? We believe it is best to correct, and therefore have a comment box on each feature. People like you allow this feedback to come in, and then others enjoy better data. In time we can use this concept of "crowd sourcing" to correct these maps or introduce new places. We would then offer this feedback to the agencies so that all maps become better.

Thanks for bringing up a very important challenge Mr. Recycle!


Like this comment
Posted by Jack
a resident of Midtown
on May 12, 2014 at 9:54 am

"Groundwater in both cities contain trichloroethylene (TCE), a chemical that has been deemed a carcinogen by the Environmental Protection Agency." (from original article)

It would be helpful if you could defend that statement, Bob. I read up on this claim a few years a go, and it was clear that only one strain of mice showed a carcinogenic effect (at high doses). There was a lot of political pressure put on to have it (TCE groundwater contamination)declared a cancer danger to humans. Political science is not, generally speaking, good science. It can also have costly consequences, such as you have just mentioned (where cleanup efforts are too costly). Installation of barriers can be effective, especially in terms of psychological relief, but they are also costly.

Perhaps a more effective approach would be to have independent toxicologists explain what levels of TCE should be of concern. If those levels are not found, then natural bioremediation should probably be the approach, and the placement of barriers should be optional by the property owner.

Your thoughts?

Like this comment
Posted by
a resident of Crescent Park
on May 12, 2014 at 11:32 am


It is proper to raise an issue about the science guiding concern about TCE. This has changed recently, so has refocused attention to these old plumes.

Even if we debate the science, each person should at least be informed of a potential TCE exposure so that they can make their own choices. As a male, we can opt to be more tolerant to TCE because we are not vulnerable. A young woman does not have the luxury. WhatsDown merely shows the area of the contamination, and offers links about the chemical health impacts.

First, the link is an article that represents the health reports associated with TCE, and draws the focus to noncancer risk to a developing embryo. Cancer risks are also reviewed.

Web Link

The conclusion states - "TCE is carcinogenic to humans by all routes of exposure and poses a potential human health hazard for noncancer toxicity to the central nervous system, kidney, liver, immune system, male reproductive system, and the developing embryo/fetus."

The EPA took this science and applied it to policy in the South Bay. The link is to a letter from the EPA requesting more attention to plumes that our state water board oversees. The link with an extract is shown below:

Web Link

"...In September 2011, EPA published its Toxicological Review of Trichloroethylene in Support of the Integrated Risk Information System (IRIS). Recent findings on TCE conclude that women in the first trimester of pregnancy are one of the most sensitive populations to TCE short-term inhalation exposure due to the potential for heart malformation for the developing fetus.

EPA uses a level of concern for non-cancer effects as a ratio of the exposure concentration to a safe dose including an additional margin of safety, called a reference concentration (RfC). This ratio is defined as a Hazard Quotient and abbreviated “HQ”. The IRIS assessment derived an inhalation RfC for continuous inhalation exposure to TCE, which is 2 micrograms per cubic meter (2 µg/m3).

Because this is a developmental effect, the critical period for exposure is considered to be within an approximate 3-week period in the first trimester of pregnancy during which the heart develops. Scientific information on the exact critical period of exposure for this health impact is not currently available; however, general risk assessment guidelines for developmental effects indicate that exposures over a period as limited as 24 hours may be of concern for some developmental toxicants.

In light of this RfC information, EPA Region 9 is using health protective response action levels and guidelines to address short-term inhalation exposures to TCE in indoor air from the subsurface vapor intrusion pathway. The purpose of these interim response action levels and guidelines is to be protective of one of the most sensitive and vulnerable populations, women in their first trimester of pregnancy, because of the potential for cardiac malformations to the developing fetus during this short timeframe.

These guidelines identify women of reproductive age as the sensitive population of concern, rather than only pregnant women, because some women may not be aware of their pregnancy during the first trimester. ..."

My alarmist nature is partially stemming from having children in the at-risk demographic. The steps to be protective are easier than the steps to cleanup, so hopefully this can increase more attention to that topic.

Like this comment
Posted by Jack
a resident of Midtown
on May 12, 2014 at 2:06 pm


I would feel much more comfortable if the source of your opinions was not the EPA, because the EPA is a very political organization, as is its science. Do you have independent toxicologists that make the claims of carcinogenicity and teratology that you seem to concur with?

My essential questions is: At the levels of TCE measured in our ground water (in ppb), is there any serious concern? If so, could you please provide the numbers and sources, in detail?

Like this comment
Posted by
a resident of Crescent Park
on May 13, 2014 at 11:36 am

NBC Investigative Reports carried this discussion on May 13, 2014 - last night. The coverage reflects appropriate engagement with this topic.

Video Coverage: Web Link

Written Coverage: Web Link

Like this comment
Posted by Jack
a resident of Midtown
on May 13, 2014 at 7:25 pm


I noticed that Lenny Siegel was interviewed in your links. When I speak of political science, I think of him.

I am asking a specific question: What are the levels of TCE in our ground water, and what are the toxicological risks (from an independent toxicologist)? Dose matters, as I am sure you understand. Dose versus $$ is the seminal issue, I think.

Like this comment
Posted by Cbremote
a resident of Mountain View
on May 13, 2014 at 11:36 pm

We lived in Sunnyvale from 1953 to 2010, so this story intrigues me for the following.

My late Mother was one of the original workers at Fairchild in Mountain View, early 1960's. In the mid 1980's my Mother developed severe breathing issues and severe allergies to common antibiotics. After allot of testing the doctors concluded her health problems were from over exposure to TCE and the other chemicals used in the Chip industry. When it was brought to Fairchild's attention they almost let my Mom go after 20+ years of service, but they didn't and moved my Mom to an office job.

In 2004 my daughter and son in law moved into a duplex over by the old Fairchild site. My Mom was so worried about them because she knew there was stuff in the ground water over there and made them promise to only use bottled water. Since living there my daughter developed severe asthma breathing issues and since she was of child bearing age when she lived there, she now has 2 daughters with Autism, one is severe and the other is high functioning. My question is if there have been any studies done on health issues in the area for severe asthma breathing issues and allergies and possibly the rise in Autism? They do believe the rise in Autism is environmental.

I am just curious and would like to know if any studies have been done.

Like this comment
Posted by Jack
a resident of Midtown
on May 14, 2014 at 1:36 pm

[Portion removed.]

I would just like Bob W. to provide data, from independent toxicologists (not EPA), about the exposure levels of TCE in local plumes. This is a reasonable request, IMO.

Like this comment
Posted by Jack
a resident of Midtown
on May 14, 2014 at 1:47 pm

To clarify, I only accept scientific information from Fox News. I think that is a reasonable request.

Like this comment
Posted by Bob Wenzlau
a resident of Crescent Park
on May 14, 2014 at 2:16 pm

Bob Wenzlau is a registered user.


It is reasonable to ask for different perspectives on complex topics. Fox News in February represented these concerns in an article "Children's Health: Number of chemicals linked to autism and other disorders doubled in past 7 years, study shows"

Web Link

I am not able to represent how Fox arrived at this opinion, but it does share that our health protection is one shared by all.


Like this comment
Posted by Jack
a resident of Midtown
on May 14, 2014 at 5:19 pm


Unfortunately, someone used my name and my neighborhood in order to trick you. You fell into the trap, and that is regrettable. I said nothing about Fox News. You, however, referenced its link. I could quote elements in that link, but it would probably make you look bad.

I am simply asking you to do your own serious analysis of the actual toxicological numbers. Are we really at risk in PA from our TCE plumes?

Sorry, but further commenting on this topic has been closed.

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