Tag Archives: environment

Mulching Plant Tour

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About a month ago, I got a chance to tour a recycling plant. This Arlington County municipal recycling plant focuses on recycling yard waste. In the spring, Arlington County has curbside collection of yard waste in paper bags including invasive vines, leaves, dead plants, pine cones, etc. In the fall, Arlington County picks up leaves in paper bags from residents and also from curbside vacuum collection. All year long, Arlington County also picks up brush curbside. All of these waste streams are treated separately at the plant, and the plant also handles dirt and rock excavated during utility work.

The plant manager said he likes to think of the plant as a reutilization plant because something goes in, they process it, and then something goes out. Their operation is really quite impressive, especially when its 2.7 acres total yard size is considered. It is mainly this plant size that limits their ability to accept more waste for processing. Their biggest issue is dirt from pipe breaks etc. that is processed here. They reuse the processed dirt and rock for backfill, but if they can’t find a use for it, they have to dispose of it in a landfill.

The yard waste has to get to 140°F to kill any invasive weeds. Because the plant is located near a residential area, they do not accept food waste because of the odor it produces. They use lime on the yard waste solely for odor control. [Lime the inorganic material, which generally means calcium oxide (CaO) with some calcium hydroxide (Ca(OH)2) not lime the fruit.] With the leaf waste, they achieve a 66% volume reduction to the leaf mulch product. Leaf bag collection mulch is mixed with dirt for final product.

Tub grinder that processes leaf, brush, wood, and spring yard waste

Tub grinder that processes leaf, brush, wood, and spring yard waste

Dirt processing machine that sorts material by size

Dirt processing machine that sorts material by size

Stone crusher machine

Stone crusher machine

Material going into trommel screen for separation. The trommel screen sorts dirt and big aggregate.

Material going into trommel screen for separation. The trommel screen sorts dirt and big aggregate.

Material coming out of trommel screen after separation

Material coming out of trommel screen after separation

As is often the case, fixing a piece of equipment involves a guy standing on the bucket of a front loader using a pole to move things.

As is often the case, fixing a piece of equipment involves a guy standing on the bucket of a front loader using a pole to move things.

Rock and concrete after separation

Rock and concrete after separation

Dirt for separation by size

Dirt for separation by size

Leaf mulch product

Leaf mulch product

Wood mulch product

Wood mulch product

Yard waste mulch product

Yard waste mulch product

The plant uses the product dirt to create this vegetable garden. It had wonderful looking vegetables, and in the past, they have entered the vegetables in the county fair.

The plant uses the product dirt to create this vegetable garden. It had wonderful looking vegetables, and in the past, they have entered the vegetables in the county fair.

Speaking to High School Students

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I was asked to speak at The Washington Youth Summit on the Environment (WYSE) to a small group of the delegates about my career as environmental engineer/health scientist. The delegates are high school students. I’ve never done anything like this before, and I can’t remember the last time I’ve spoken to a group of high school students about anything. I was told to talk about my career and talk about specific projects on which I’ve worked. I prepared a few slides on the basics of risk assessment as that is the general field in which I work now and then quite a few slides on my dissertation and a few slides on the project I am currently working at work. I wasn’t sure what to expect. Would they be interested in this at all? Would my slides be interesting or too far over their heads? I took out what I thought were the more advanced and complicated slides and just focused on graphs and photos. I wanted to focus on the big picture.

Part of my problem with giving this presentation was, the more educated you become, the more you take for granted what other people know. At least, I have that problem. I have had so much math education including three semesters of calculus, differential equations, linear algebra, probability, statistics, and biostatistics, that I’m flabbergasted when I meet people who can’t do or understand basic algebra or understand what a square root is. Certainly, you can make an argument that this is a sign of the failure of the US education system, but people’s education level is what it is. If you want to explain something to someone, than you have to be able to explain it to them on their level. These are high school students, and I can’t expect them to know information that is not taught until college or after. Thus, I have a group of high school students that I need to talk to about the work that I do and the work I did to earn my Ph.D. I am not entirely sure how to do this. I don’t quite frankly remember what I knew in high school. I have no idea what these students know. I don’t want to bore and confuse them by talking at so high a level that they can’t understand me, but I don’t want to insult them by explaining things they already know.

I am really not sure how I did. The one thing I am fairly sure about is that I babbled and rambled a few times. I am really not the best speaker. I am not a bad speaker, but I do much better if I have a set text that I am reading or very specific things with high points written on slides. I didn’t do that for this talk because I wanted to be able to change what I was saying once I got there and started getting questions. They did ask me questions. They asked me great questions in fact. However those questions made me realize just how much I know and forget that other people don’t know. That is in no way meant to be an insult to these students. I was really impressed with them. Like I said, they asked great questions. Also, they were very polite and politely listened even when I am sure I started to ramble. I really appreciated their attentiveness, and I loved their questions.

For example, one of the first questions I got was on one of my first slides, which had the word epidemiology on it. I was asked “what is epidemiology?” This is probably where it hit me that I had no idea what they knew. It didn’t really dawn on me that some (or all) would not know what that word meant and what that science field is. Again, that is not an insult to them. If anything, I was annoyed with myself for not considering when I learned that word. I am glad I was asked the question. It gave me a chance to tell them about John Snow and the London cholera epidemic. I am fairly sure all epidemiology courses are legally required to start with a discussion on John Snow and the London cholera epidemic, so I had fun telling them about it.

I can’t remember all the questions I got, but I got quite a few. I loved this because that meant the person asking the question was listening and engaged. When I describing issues related to soil and groundwater contamination, I got a very simple question as to how these chemicals get into the soil and groundwater. I LOVED this question. I can’t describe all the reasons why I loved this question, but one is because I am an engineer, and I get frustrated when people think we build things and then no maintenance is ever needed. Bridges in the US keep falling down, and the American Society of Civil Engineers gives our infrastructure a D+ grade. One of the reasons is lack of maintenance. I got to explain to the students about maintenance and inspections and things simply not being designed or built to last forever. I also explained how decades ago, people used to just dump chemicals in the ground or water and never think of the consequences.

I also got some questions of how to find out more information on different topics and things I discussed. They wanted to know more. As I always want to know more, how could I not like these students? I hope some of them already have or are now on the internet reading more about the topics I only lightly discussed. Maybe one day I will meet them again professionally.

Scrap Metal Recycling

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As I’ve been renovating my home, I’ve been saving all the metal to sell it for scrap. I had no idea how much money I could make, but for the sake of the environment and proper disposal, it should be recycled. Also, if I made $5 from the scrap metal, then that was $5 I didn’t have before. After saving all the metal from Phases I and II of my home renovation, this is what I had accumulated.

metal scrap metal scrapThe ferrous metal (magnetic) included all the nails from pulling out drywall and molding, various screws, electric outlet and light switch plates, vent covers, ceiling fan parts, appliance parts, and much more. I also had a bunch of brass doorknobs and light fixtures. I had copper from electrical wire, piping, and coaxial cable. Finally I had four overhead fans and various other metal parts.

What was the results of selling this metal? I made $76! I am really happy with this. The majority of the money came from the ceiling fans and the various brass parts. Clearly copper prices are still high.

I’m going to add this to the list of reasons why it’s great to do-it-yourself. I carefully saved all the metal, separated it, and then sold it. I have never seen contractors do this. At times, electricians and plumbers might save copper, but they will sell it for their own profit. My electricians actually tossed scrap copper wire into the trash, and I went back and pulled it out. [It was a clean trash bag.] It literally pays to do-it-yourself.

 

Short Term Radon Test Results

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Previously I wrote that I was testing my house for radon. I got the test results back this week, and the test results came back as an average radon level of 2.9 pCi/L. The good news is this is less than the 4 pCi/L action level. The bad news is this is still elevated above average house level of 1.3 pCi/L. This test involved collecting radon over four days. At work, I am currently working on a project that involves looking at the indoor air variability due to radon or volatile organic compounds intrusion from the soil and groundwater. Thus, I know better than most how variable indoor air concentrations can be. They can vary a lot. Therefore, before deciding what to do, I have considered the following items:

  • The test was done in winter under proper closed house conditions. Closed house conditions means keeping the doors and windows closed except for normal entering and exiting the house through the doors. This is not an issue in the winter because it is cold. This is also one of the reasons winter is one of the best time to perform the test, but it also means that the test will lead to higher results than if more open house conditions are maintained. When the weather is nice, I like to open the windows and doors, so that would generally mean at least during those times, the radon concentrations in my house should be much lower.
  • The test was performed over four days. As I stated, indoor air concentrations can vary a lot, and in terms of those fluctuations, four days is relatively short term. Even ignoring the seasonal effect of closed versus open house conditions, the long term average radon conditions could be much higher or lower than 2.9 pCi/L. The reasons are not fully understood, but exterior temperatures and precipitation can affect it. A long term test over several months or even better a year, will give a much better understanding of the average concentration. If the results had been 1.3 pCi/L or less, than given the conditions, I would probably not be at all worried that the long term concentrations would be higher.
  • The EPA recommends that the test be performed in lowest habitable portion of the house. As such, I placed the test in the guest room for that and other reasons stated previously. However, I am almost never in the guest room. I don’t have guests that often, and the door to that room remains shut most of the time. Thus the only air exchange in the room is via the ventilation ducts and a little underneath the door. Furthermore, my bedroom and all the common areas of the house (kitchen, living room, etc.) where I spend most of my time are upstairs and should have lower radon concentrations than the guest room. Therefore, even if the results from the guest room do accurately represent average radon concentrations, they are borderline for taking mitigation action and probably represent the highest levels in the house. While I don’t want to expose my guests to undue risks, especially since my guests are generally people I like or love, do I want to mitigate based on the results from this room?
  • Finally, I’m a scientist, and I believe in validation and replication. This was one test result, and home test kits are generally not considered the gold-standard of any type of test. There is no doubt at least of some amount of inaccuracy with it.

Therefore, I have decided to test the house again, but this time for a longer duration. I have also decided to run two tests simultaneously. I plan to place two testers in the house, one in the guest room again and one upstairs in my master bedroom. I have ordered a long term home test kit that can be used to test between 90 and 365 days. I plan to run the test over an entire year to get a much better indication of what the long term average radon concentrations are in the house. Also, by testing both the guest room and master bedroom, I can better understand what my average exposure is both in terms of the average annual concentration and in the rooms where I spend the vast majority of my time. I will also add that while the guest room is a guest room now, as it is bedroom, legally and real estate-wise speaking, and thus in the future it could be a normal bedroom if my life changes or if I sell the house. Therefore I still consider it important to know what the long term radon concentrations are.

Check back in a year, and I will let you know what happened and how I am proceeding.

Testing My House for Radon

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I’m testing my house for radon, and you should also. Winter is the best time to test your house for radon, which is one of the reasons I am testing it now. What is radon, and why am I testing for it? Keep reading.

What is radon? It is an odorless, tasteless, invisible gas that also happens to be radioactive. It is produced naturally from the decay of uranium, which occurs naturally in soil across the United States, and other countries and continents. The United States Geological Survey (USGS) has this neat map showing uranium soil concentrations across the US. Due to its radioactivity, radon is a carcinogen. In fact, it is the second leading cause of lung cancer after smoking. Radon gas is pretty much everywhere, both outdoors and indoors. Like all carcinogens, there is no safe level of exposure. You can’t completely avoid exposure because it is naturally occurring, but it is best to avoid it if you know it is present.

The US EPA estimates that the average home has an indoor radon concentration of 1.3 pCi/L, this means pico Curies, a unit of radioactivity, per liter of air. If your indoor air is above 4 pCi/L, then they recommend you fix your home. I’ll get to what fixing your home means next. Finally if the indoor air concentration is between 2-4 pCi/L, then they recommend you consider fixing the house. It is in that range that the concentration starts to get high enough above background that you might want to take action.

What happens if the radon concentrations in your house are high? First, don’t panic, your house can be mitigated to reduce the radon concentrations. You can hire a professional to install a mitigation system in your house. A mitigation system can either prevent radon gas from entering the house, or it can remove it from the house once it gets in. For example, one type of system sucks or pulls gas from beneath the house and then pipes it safely above the house where it can disperse into the atmosphere. Mitigation systems can be very effective and will greatly reduce your risk of lung cancer due to radon exposure.

Is your house at risk? As shown in the USGS map, some areas have higher concentrations of uranium in the soil than others. Areas with higher soil uranium concentrations will generally lead to higher radon gas concentrations. Also, houses with a crawl space will generally have less radon infiltrating the house than houses built on a slab or with a basement. The crawl space can allow the radon to dissipate before rising into the house. Houses with cracks in their slab are more susceptible because the cracks serve as a pathway for the radon to rise into the house. Also, pipes and conduits such as for wires from the house to ground can also allow radon to enter if they are not properly sealed.

So how do you find out if elevated levels of radon exist in your house? It’s fairly easy. Many states regulate the testing of radon, so you may try contacting your state radon department if it has one. Most of the time, you can go to your local home improvement store and buy a test kit for about $20. That’s what I did. The test kit I bought included two little containers that detect radon. The test kit had certain specific directions for the test containers such as they needed to be at least three feet off the floor, at least three feet from an exterior wall, etc., and they needed to be open for four days. The test containers were supposed to be placed six inches from each other. I presume you get two that are supposed to be placed in the same location for replicability. So here are the high tech test kits.

Both radon detectors placed for testing

Both radon detectors placed for testing

Yes that is a tape measure in the photo because it said to place them six inches apart, and I’m an engineer. Now be quiet. The detectors should be placed in one of the lowest habitable rooms of the house. My house is built into a hill such that the front door on the first floor is ground level, and the back door of the second floor is also ground level. I chose to place the detectors in the guest room, which is on the first floor and in the back exterior corner of the house. The back wall and 3/4 of the side wall of the guest room are underground exterior walls, and thus this room would be one of the most susceptible to radon infiltration from the ground. The room that serves as my office and workout room is next to the guest in the front exterior corner of the house. Two of its walls are also exterior, but only about 1/3 of its side wall is actually underground. However, there is a crack in the slab about two feet long in the office, so I considered whether the test kits should be placed in this room. [Due to the extensive renovation I’ve been doing on this house, I know where all the cracks and openings are.] That crack could serve as a major route for radon to enter the house. However, I ultimately decided that the guest room would be more susceptible to radon infiltration because of the amount it is underground.

After choosing in which room to place the detectors, I then found a good location that was far enough away from an exterior wall and above the floor. I then proceeded with the testing protocol. I unscrewed the containers and let them sit for four days. Whew, that was exhausting. I deserved a drink after initiating that test. Here is one of the detectors unscrewed. It’s quite simple looking.

Radon detector open to run test

After I let them sit for four days, I screwed the caps back on, filled out the form that came with them, and mailed them into the lab. It cost $30 to have them tested, so with the cost of the kit, the entire thing cost me $50. I consider $50 a small price to pay to make sure I am not unknowingly breathing in a carcinogen everyday. I’m currently waiting for the results from the lab, and I will update my blog when I get the results.

One final note, I said at the beginning of this post that winter is the best time to test for radon. The reason for this is winter tends to be the time that the radon concentrations in a house would be at the highest. When the weather is nice, people tend to open windows  for ventilation instead of using the AC or heater, and people just tend to open doors more often to go outside for whatever reason. Thus in the winter, the house is more closed off, and radon concentrations can build up due to less exchange of the indoor air with the outdoor air. Where I used to live in south-eastern part of US, I probably had windows open more often in winter, as I constantly used the AC in the summer, so this might not hold true. That and the fact that indoor air concentrations can vary day to day, is why experts recommend that if you get high levels detected with a short term test, you consider doing a longer term test such as over several months, to determine what the longer term average is. The test kits do have false positives, especially at lower concentrations, so if you test your house, and it comes back high, once again, don’t panic. Test your house again, this time with a longer term test, and see what the longer term concentration is, and then determine if you need to take action. However, don’t remain ignorant about the risks. Test your house; it’s important and could save your life.

For more information:

Las Vegas Wash

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I don’t know about anyone else, but when I think of Las Vegas, I think of the Strip, casinos, shows, and desert. The only wildlife I think of is that of the human variety, generally in an inebriated form. Thus, on my recent trip to Las Vegas, I was surprised to learn about the Las Vegas Wash. It is the lowest part of the valley in which the Las Vegas metropolitan area sits. All storm water and urban runoff in the area drains to it, and it eventually drains to Lake Mead. The Wash has been increasingly eroded due to the increased flow into it from the increased Las Vegas metropolitan area urban runoff. In the past decade or so, the LVWCC has constructed numerous structures to reduce erosion in the Wash and increase the wetlands in it. Structures such as this.

And this weir.

They have also been removing non-native plants and planting native plants. None of which I can identify in the photos below.

Plants that can amazingly grow in the desert that is Las Vegas.

All of this has created a very pretty area, which is really nice to hike along, assuming the weather is nice. It has some lovely views of the nearby mountains.

And beautiful sunsets.

In some places, it allows some nice views of the Las Vegas Strip.

Next time you are in Las Vegas, if you like the outdoors and want to get away from the Strip, I highly recommend checking the Las Vegas Wash out. In a later post, I will be posting photos of the wildlife I saw on it.

 

Industrial Waste Site Tour

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I recently toured an industrial waste site where the groundwater underneath is being remediated for perchlorate contamination as well as other contaminates. Perchlorate can be naturally occurring, but in this case it is from historic rocket fuel and explosives manufacturing. The groundwater is being remediated partially through the use of bioremediation (i.e. microbes).

Lots of chemicals on site for the remediation, like ferrous sulfate.

Hydrogen peroxide

Nutrient for the microbes.

Lots of nutrients for the microbes

The label on this container notes the dangers of the concentrated phosphoric acid, which it contains. It also notes that there is a $800 deposit on the container, so you definitely want to remember to return the container.

The main part of the site is a series of fluidized bed reaction tanks.

With centrifugal pumps to keep the fluids moving.

More chemical storage tanks

At industrial plants, pipes always need to be labeled.

The first two mailboxes are labeled “PAP Sample to Lab,” and the second two are labeled “Clean Bottle Return.” I actually have doubts that these are really being used for pick up of samples to go to the lab. In general, samples need to be refrigerated once taken, and they should not be left in a metal box to bake in the hot sun.

Finally, always remember to drive slowly