Interviews draft: awaiting interviewee approval
index
Richard Berg, geologist
1
Scott Bishop, designer
2
Mary Pat McGuire, landscape architect
2
October 2017 Chicago, il
conveys perspectives
October 2017 Boston, ma
documents
October 2017 Chicago, il
exclusionary/inclusionary words
Michelle Laboy, architect/engineer
represents diversity of thought
maps relationships needed to address the issue
3
Steve Mabee, geologist
5
Chris Hirsch, environmental scientist
6
Anonymous, geotechnical engineer
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Tom Palmer, Willet Pond manager
10
October 2017 Boston, ma October 2017 Amherst, ma
February 2018 Canton, ma
March 2018 Boston, ma
March 2018 Canton, ma
Copyright © 2018 by Pankti Sanganee and Margaret Owens All rights reserved Living on the Unknown
Red words represent masking words Blue words explain a situation or scenario
Richard Berg
Scott Bishop
Geologist | Great lakes geological coalition | Illinois Geological Survey
Registered landscape architect | Bishop Land Design | Northeastern University faculty
How important is it to understand the glacial deposits?
Why do you think is it important to understand the ground beneath to develop a resilient city? Where do you build your foundation? How does zoning be placed? Where you get your food from? Where does your water manage and drain into? How can you develop a water management strategy or flood resiliency if you have an unknown factor in the plan?
Understanding glacial history is vital to the future of our cities. Illinois has been through three glacial periods. Thus it has a diverse landscape rich in sand and gravel making it a lucrative state for quarrying. On Route 82 in Illinois, there is an old quarry now functioning as a stormwater lake. Chicago’s funneling of stormwater into the old quarry could potentially put nearby aquifers at risk of contamination. We are ignorant about the realities of quarrying and that sites actually dig down into aquifers where many get their drinking water thereby producing the signature lakes seen in pits. These new water bodies are often polluted, and as part of regional groundwater system, become a major risk for drinking water in surrounding communities. How important it is to look into urban soils and their current conditions? Are aquifer systems addressed while discussing city development? No, aquifers are overlooked as issues of national security. A single aquifer reaches many people, and with development we often open up windows to our drinking water by exposing aquifers. The blue baby syndrome in Indiana and outbreak in Ontario... as well as the Woburn Massacre (John Travolta documentary) are just a few cases resulting from polluted aquifers generating polluted drinking water. Even stormwater detention needs a second look. It’s common to store polluted runoff in basins without regard to infiltration. And this means without regard to the high risk of groundwater contamination. Contaminated water that flows into agriculture sites then impacts the food we eat. Soils can be an important source of lead in drinking water and so close monitoring of urban soils can indicate risk areas. Lives can be saved by looking at these soil and water dynamics. Children are playing in highly contaminated parks and gardens due to urbanization and its runoff. Why is it so difficult to gather this data and make it accessible to public? Core sampling is very expensive in the city area and it is difficult to gain access to private lands for mapping. All data is divided by parcels. Every time a new core needs to be drilled because we lack a data bank of previous mappings. As there is no comparative data we cannot understand the landscape as a whole and thus decide based on just a single parcel’s data. It is something we are working on in our office. One needs to have a citywide data to actually determine construction on one parcel - they are directly impacted by landscape-scale geology beneath, there’s subsurface dynamism.
A vulnerability map and a clear subterranean map is required to do risk analysis and to develop unique solutions. We cannot imitate solutions. With this knowledge we can develop a truly resilient city plan that considers unique solutions. It’s important to make projections about the future of a landscape. For example: if a site is clay then check if it would crack based on the depth of the soil that sits on it and if it’s around an aquifer. What would happen if there was also saltwater intrusion? These scenarios, when combined with data, can be very alarming. We as designers need to see how opportunities can be created by synthesizing disparate datasets on subsurface conditions and project them with designs.
Mary Pat McGuire Registered landscape architect | Water Lab| Univeristy of Illinois faculty What do you mean by the phrase ‘water territory’? How do you consider subterranean landscape in your research?
City Digital is a really fascinating project that the City of Chicago is working on. They’re 3d-mapping subsurface infrastructure and soils in order to understand what is actually going on down there and to hopefully make smarter planning decisions. The Great Lakes Geological Mapping Coalition has worked with Kentucky State to establish geological maps for every county in Kentucky. These maps are then analyzed to understand risk for future growth. They have been very active with this information and have gathered tons of data on it. They share it with the planners and zoning committee as well as developers. It is very ingrained in their culture of practice and planning. The data can also be used for zoning to shape what kind of septic systems should be built, how to manage stormwater, the density of development, and what subsurface infrastructure is most resilient. Partners who benefit from this are health department, real estate and planning committee of a town.
It means reconfiguration of under-performing urban surfaces as landscape infrastructure for water. I am currently working on a project called depave Chicago. Upipe tributaries means streets are engineered as the primary tributary to the existing gray infrastructure system. Surface conversions to promote infiltration of rainwater into the geologic substrata of the Chicago coastal realm is central to the project. Such an effort would be the first, large-scale landscape project that infiltrates water where it falls, diverts water from the over-taxed combined sanitary-sewer system, and promotes groundwater recharge and restored water flow to Lake Michigan. The target soil areas are the locations of the former dune ridges of the Chicago lake-shore that were paved over during urbanization. This project would tap into those soils as an ecological infrastructure of the city, and celebrate Chicago’s natural heritage which is currently invisible to the people of Chicago. Geological origins of cities so rarely talked about. It feels like a lot of conditions in which we live have been able to leave the base structure unacknowledged. In the 1900’s city plans used to actually acknowledge the patchy nature of soils. Because of this we can read a skyline of a city and describe the geology below. It is fascinating to see how they to relate and tell the story of what is beneath.
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Which are the other organizations researching in the area of urban soil mapping? How is this information shared and who can benefit from it?
Michelle Laboy Registered architect and engineer | FieLD Workshop| Northeastern University faculty
Why are soils and groundwater important to cities? I’m interested in water and design - how invisible systems shape architectural process, how design incorporates data, the social agenda of design, and design as a vehicle to create understanding of ecologies and landscapes and systems that support us. Things that we don’t see in our everyday lives can be damaged without an understanding of the consequences. Buildings take a defensive position against groundwater and that’s not necessarily going to become a problem until it’s too late. Can you give us an example? For instance, Boston’s groundwater is lowering. The wood pilings within the 2007 Groundwater Protection District care about groundwater because the lowering of levels leads to rotting. When there is less support, buildings settle. And this matters because the fill that Boston developed on has always been unstable and consequently, they have always needed pilings supported by the upward pressure of water in the ground. But Boston’s water table is sinking. These pilings begin to rot when they are exposed to air from low groundwater levels and their failure leads to settling. Settling on these soils would be terrible news for buildings. Bad for both buildings with wood pilings and newer high-tech pilings or foundations. Lawsuit by residents of Beacon Hill spurred well monitoring in Boston. Because of their efforts, the City of Boston instituted Groundwater Overlay Districts around a chunk of Boston where wood pilings are prevalent. Then in 2007, as a result of a consent decree with the epa, the rest of Boston received a Groundwater Conservation Overlay District to reduce stormwater loads and improve groundwater recharge. These two districts have different goals. One doesn’t want wood pilings to rot and the other is worried about regional groundwater levels.
draws down groundwater levels. But, lower groundwater levels lead to the rotting of wood pilings. So, in order not to damage nearby wood pilings of other buildings, the mbta pumps in 70,000 gallons a day of potable water from the Quabbin Reservoir. This small area is requiring massive movements of water across the landscape. The built environment also consumes a lot more water than measured in metered intake/ outtake. Electricity infrastructure requires cooling, pumping groundwater out of basements. Something people don’t talk about often is the fact the groundwater levels have an effect on boundary conditions above ground - drier areas, hotter condition. Wetter grounds are cooler. Pervious surfaces with good groundwater levels will lower temperatures. Are there risks to Boston’s infrastructure that people would be surprised to hear about? Boston is mostly fill of unknown origin and we don’t know how groundwater moves through it, don’t understand its ability to hold water. Fill has never been a good material to build on - it has never been stable and so has always required us to use pilings going down thirty to forty feet. There’s a risk of liquefaction in sandy areas when earthquakes hit. This matters because many cities built over the last 200 years on wet sand have never had experience with earthquakes and so are not prepared for the effects. Boston has very heavy buildings in Boston, especially masonry, that are not reinforced _could collapse due to liquefaction as seen in the Umbria, Italy earthquakes. Why does saltwater intrusion matter? Intrusion of ocean water into the voids in soil previously occupied by groundwater are pushed by saltwater. They no longer have the pressure of groundwater to push back and so saltwater begins to occupy areas where freshawater used to be. Then there’s the new sediment chemistry and ecology. We may see oxidation of building materials previously untouched due to new microbial ecologies. This poses serious risks to the stability of foundations.
How does the city keep track of groundwater levels?
Are there aquifers in and around Boston?
The Boston Groundwater Trust was established in the 1990s (is a government partner) and installed water monitoring wells just to see where groundwater is- not to map it. Most of these wells are on public land such as sidewalks and streets. A few were donated private wells. They have a network of 500 monitoring wells and Boston University is sampling 900 groundwater wells around Boston to measure the presence of certain chemical compounds and microorganisms that can be used as indicators for saltwater intrusion.
I’m not sure about the specifics but any aquifers underneath Boston are not for drinking. Cape Cod, on the other hand, is mostly sand and they’re worried about saltwater intrusion into their [drinking water] wells. Furthermore, the underground saltwater will change ecologies such that new species will need to be planted or new species that’ll take over on land.
How can we understand these sites in relation to the regional scale? Pay attention to the fact that Boston uses different water than surrounding suburbs and so the consequences of its behavior not evenly distributed. mbta Back Bay is leaking, drawing in water into the station. They are pumping it out through stormwater drains and so the groundwater is not being recharged. This dramatically draws down groundwater levels. But, lower groundwater levels lead to the rotting of wood pilings. So, in order not to damage nearby wood pilings of other buildings, the mbta pumps in 70,000 gallons a day of potable water from the Quabbin Reservoir. This small area is requiring massive movements of water across the landscape.
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Why do you think the information and research we’ve discussed is not applied in actual land practices? It’s not at the top of policymakers’ list. When you say climate change they think sea level and temperature rise. But, you’re seeing patterns of groundwater stress worldwide. You’re seeing areas reach extremes worldwide, depleting aquifers, water leaves state in form of agricultural products, wet areas are getting wetter and wetter, dry areas getting drier. London was built after they depleted groundwater aquifers, now groundwater is rising at such a pace that is they are in trouble. They will have to learn how to live with water.
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Steve Mabee, PhD Massachusetts State Geologist| UMass Amherst faculty
It has been difficult to get recent soil and groundwater maps for the Boston metropolitan area. What can you tell us about the typical conditions in this part of Massachusetts? Massachusetts used to be glaciated and when the glacieers retreated they left depositions like the drumlin that is now Beacon Hill. What’s interesting about the Boston area is that, post-glaciation, it was inundated by the ocean. When the ocean retreated, it left Boston Blue clay. Clear of the ocean, the coast became very marshy and so a typical cross section in the Boston area is bedrock/ glacial till/Boston Blue clay/marsh muck/ fill. Glaciers shaped the groundwater landscape. Glacial valleys provide very linear aquifers, often don’t align with modern rivers. A lot of glacial lakes were dammed by sediments, varves, and lacusterine deposits. After they drained, sand and gravel was left on top, leaving us with present-day surficial aquifers that are mostly unconfined. Most of Boston was built on fill material which can be unstable. But, why is it unstable? Do you know of any geological impacts this fill has had? Fill is unstable because it is atop old, uncompacted marsh deposits that are also above Boston Blue clay which is susceptible to liquefaction. Geology is often seen as very static but a small shift can mean big changes for people. In the next 50 to 100 years, do you see any problems arising from ignoring geology? If a building is on till or bedrock they should be stable. But areas at risk of saltwater intrusion could face a lot of wetting and drying of pilings and that really makes them deteriorate. We’ve noticed that many geological datasets have a very geometric cutout where Boston and its surrounding towns are. Why is that? Expense. It’s expensive to conduct studies in densely populated areas. Data provided by well drillers is available online but only 15% of well locations have gps locations - not in as good shape as other states.
Chris Hirsch Environmental Scientist| Neponset River Watershed Association
How and when do you think of soils? The only time we think about soil and sediment control is during construction. We are very strict with the bylaws and also do a fair amount of green projects. We do soil assessments for the site, determining infiltration rates and degree of connectivity to groundwater (gw). If a site is highly interactive with the water table then we do something different and line the project or ensure that site drainage would not impact the local groundwater levels. We generally do these projects using the 319 grant system, a federal program established through the Clean Water Act and administered by the state. Work done with 319 money has to be done on public lands and so do much of our work with parks and schools and include an educational component. So, you don’t work with private properties? I don’t typically interact with private property but we are asking the town to account for all bmps. There are a lot of methods and devices to deal with stormwater runoff. They have pollution plans set by the epa that outline water quality standards. It’s in the best interest of the town. bmp
stands for Best Management Practices, correct?
Yeah, when we say bmps that includes the technology and techniques used to manage stormwater runoff. So, a lot of developers are implementing Best Management Practices but there’s no cumulative record that people can reference to see what works best where. Also, it would help the town to know what their landscape looks like. Stormwater management plays a big role in maintaining groundwater levels but we’re seeing water tables drop in places like Boston. Is that an issue here? What factors do you see impacting this? Is infiltration the only remedy? Yes, decreasing groundwater levels is definitely an issue here. Our primary concern is the infiltration of groundwater into sewage lines by way of cracks. So, the town ends up paying Deer Island by the gallon to treat groundwater while also lowering the water table. We do an educational program with schools. We have done a rebate program for high efficiency showers, toilets, and other fixtures through the mwra. We try to run campaigns- Brown is the New Green, where we encourage homeowners to decrease lawn watering. We try to look at enforcing private wells but the town doesn’t like to superimpose on private land. Each town has their own response to drought but we’d like to see a coordinated statewide response. If one town does one things and another does their own thing then the town downstream suffers from the practices of the town upstream. Unification of efforts would respond more effectively to hydrological considerations. What is the reason for the drop in groundwater levels? A recent report indicated that groundwater levels have been on the rise in New England over the last hundred years. The scenario has flipped. The main issue is basically continually pulling water from the ground then
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putting it back. Most of our towns are dependent on groundwater and they use the sewer system. So water is pulled from the ground and then sent to Deer Island. That water does not come back. We’re pumping water out and then sending it away without recharging our own land. In summer there is little regulation on private wells. There are regulations but very little enforcement. Add to this that summer also has the highest rates of evapotranspiration. In your wildest dreams, with all the funding and political support you needed, do you think there would be a way to redo the sewer system? Yes, there is. Through septic. Most of the Town of Sharon is septic and it infiltrates water back into the ground but most of the towns don’t do it. But septic has its own drawbacks. The easier fix would be to hook up to the mwra for seasonal uses where they’d receive Quabbin water. The problem is that Quabbin water is ten times the price of local water which isn’t really feasible and, so, it’s hard to sell. Quincy is very concerned with their groundwater levels and sewer infrastructure because they get a lot of infiltration and inflow. If the gw level is higher than the sewer infrastructure then they get a lot of seepage and then they pay a lot for the inflow they send to Deer Island. It was really interesting- I was talking to the town engineer of Quincy and he said how they had a big flood in January and because they had lined the sewers since the last big flood, the flooding was markedly decreased. When they were unlined, the stormwater overwhelmed the ssos that emptied into water bodies that were flooding the streets.
Do you have issues with arsenic contamination? We do have some arsenic-impaired water. This is more related to what railways did back in the day. Before RoundUp was invented, the railroad would just go through and spray arsenic on the land to kill all the plants. It’s still present in the soil. Our main concern is pollution from PCBs- in terms of legacy stuff. Is the town and your organization looking to add on to the Neponset River Greenway? Do you think the “green” buffer works to filter stormwater runoff ? The goal of the Greenway wasn’t to create a buffer. It was a co-benefit. The goal was to bring people to the river for recreaion. But Finnigan Park in Dorchester, which opened last summer, made a conscious effort of trying to make it wildlife friendly. __ They have a prairie-like grassland in the middle and a restored saltmarsh on one side but I don’t know if flooding was a major driver as to why it was done.
Even with data on how many private and public wells? We can point out how much is beyond our control - all the private wells that are not monitored versus the public wells. There’s also the a high development rate, sudden growth in the last 5-10 years. Every time a wetland is filled for development you lose infiltration. It’s more of a past thing where they did a lot of legacy filling, before there was a lot of regulation. Have you seen any increase in salinity in the Neponset River or other areas where the groundwater table has dropped? We do not monitor groundwater quality. Many towns who are impacted by saltwater intrusion like Quincy and Boston are already using mwra water. We do have a concern for salinity from road salt. We see that increasing here and statewide though there’s not a lot ofdata locally. Do you have water quality concerns regarding the many oil and gas tanks along the Neponset?
Anonmyous Geotechnical engineer specializing in groundwater
In what ways do you have to consider groundwater when building? Well, we have to decide if we can build below grade, obtain a permit for groundwater pumping and understand treatment requirements. Once they get a permit to de-water there is no limit to it generally. What are you typically involved with?
I assume they are being monitored very heavily. We have esuen (sediment monitoring program) where we look at stream and river pollution over a twenty year timespan. We have forty different sites in the watershed. mwra does the monitoring though. A lot of our focus is on stormwater and making the river safe for recreation at all times. 75% of the river is fine during dry weather. During rain, however, e-coli levels increase 10% because the stormwater coming from off the land has picked up pet and wildlife waste. At that time only 5% of the river is safe. We don’t have an exact idea of what’s happening with septic waste.
I conduct risk analysis on prospective properties and recommend whether or not to buy the land e.g. are there too many risks or considerations that are cost prohibitive like pollutants? My main concern is how buildings are impacted by contaminated groundwater - how the impurity can make people sick and not so much about what the buildings put into the ground. Construction materials are so heavily regulated that it’s not really an issue.
How do wetlands buffer communities from the impacts of flooding? In 1920 there was a plan to fill Fowl Meadow and industrialize it. They also filled a lot of the river downstream for the potential project. Once they filled the wetland, they realized the quantity of water that came through the area was going to flood Boston and so they would need to channelize it. The money fell through for filling the section and thank god we still have the wetland which protects Boston. It slows velocity and allows for some infiltration. Looking at Turner Pond, the development around there is highly septic. The pond has high phosphorous and occasionally high bacteria counts. I’m wondering if there’s a lot of communication between the septic systems and the pond.
If you build let’s say five feet below the groundwater level, the basement has slab joints through which water can seep in and contaminate the building. You might get these from adjacent land uses like gas stations or laundromats.
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How can pollutants enter the building?
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What are the particular impurities to be considered? There are many of them. For example, gasoline plumes, dry cleaners/laundromats, and industrial cleaning all carry risky chemicals.
Tom Palmer Willet Pond Manager| Neponset River Watershed Association
With climate change, has there been much talk about soil salinity? Salinity is a layman’s term. Saline concentration is what you’re talking about, but there’s a gradient. You look at saline concentrations based on where you are relative to the coast and the hydrological connectivity to consider corrosion risks- especially in the av and ae zones. How salt will react with infrastructure is important so you may use pvc instead of steel. Do you consider future conditions in projects now? Mainly we look at sea level rise and how that will impact our projects. If you have to raise a building half a floor then you have additional parking and ada concerns. We also look at 2030 groundwater levels. Do you have pollution concerns when de-watering? The potential to mobilize groundwater by pulling pollutants along the water gradient? Contamination and pollution are problematic words. They are very general terms we tend not to use. They are relative terms. The question you should ask is: are they above or below a certain threshold? I generally don’t deal or think about drinking or discharge of water. Do you believe construction of these new development impacts groundwater positively or at all? Before we develop any project we have to get permission from the Boston Groundwater Trust and demonstrate that our plan won’t impact the groundwater flow. Our project is well water-proofed. And this answer is complex to answer as it cannot be generalized. It has to be understood on a site-by-site basis. Due to the glacial deposits, conditions can be very inconsistent from one point to another a hundred feet away. Other places like Cape Code can count on consistency of its groundwater levels. Glaciation makes things more complex. I just think of built projects. Environmental projects are different. For example, if a gas station has caused a plume in the groundwater and is next to residential project we would place a subsurface seepage barrier wall. Thus we have to mitigate the plume. We work with our neighbors if and when necessary.
Who has septic around here? You’ll see most septic fields at the edges of the watershed. Nitrate pollution by septic systems has been cropping up over the course of our research as a major issue in water quality. Is there a fundamental problem with household septics? The best a septic system can do is remove pathogens and break materials into nitrates and phosphates but there’s no getting rid of the nutrients. Take Willet Pond for example. It was built in 1914 for a tannery in Norwood and has experienced very little sedimentation over its hundred years. The southern end of it is high in peat, a very anoxic environment, and raises suspicions of septic leakage from bordering homes. Cape Cod also has to be careful because it’s a sole source aquifer, with relatively uniform sand, and high water table. Nitrates and other pollutants move quickly and easily through the ground there. Now, they’re having troubles with eutrophication and shellfish loss (loss or ban on harvesting?) from nitrates and other pollutants. Do towns in the Neponset River Watershed use mostly groundwater? Weymouth has tapped out its groundwater resources. They want to get Quabbin water and so the Massachusetts Water Resource Authority (mwra) estimated that to extend from the nearest point in Willet to Weymouth it would cost $50 million. This kind of expense has shelved redevelopment plans for a military base and I can see it affecting property values in the future. What are the major sources of pollutants around here? Any notable instances of water pollution? A well in Canton near Neponset Street failed because it was pulling trichloroethylene (tce) or other solvents used to wash cars at the Cumberland Farms. It turn out that the pollutants were traveling from the ground near the store, underneath the river channel and up into the well. The well owners went on to dig a deeper well 500 feet away, further into Fowl Meadow. Most of the old landfills in the watershed are unlined and the area — have you seen pollution as a result of this? Postwar (wwii) towns were scrambling to find space for trash. Southeast Mass was a major player and there were ash heaps near the cranberry bog region. All the garbage used to be incinerate at a Rochester facility but then towns shifted to landfilling. When the Big Dig was going on they’d test the fill coming out of the ground so that they’d go to the appropriate facilities. Often, the clean fill was previously undisturbed earth and the contaminated fill was from old land that had been tainted by tanneries including lead and arsenic. These factors determined the level of protection required of their end destination. They struggled to find sites for all of the material that was removed from the site and situated some of it in the Blue Hill.
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Are there conflicts among towns for water resources? Rules were bent or broken and fill was put in places it shouldn’t have been. At one site there were fifty acres of woods between two landfills. They placed Big Dig material in the middle without capping. This was the first time in Massachusetts that a landfill had been situated in an area that had not been damaged. There is now thirty feet of Big Dig fill adjacent to the Blue Hills. You can tell when a landfill has not been capped because it accumulates its own sort of soil around the edges. When rain percolates down through the material, a rusty iron buildup accumulates at the base. It’s bright orange. Capping prevents the percolation of rain through material and therefore its distribution of contaminants through that method but it doesn’t address subsurface interactions. Most of these landfills are not lined. A lot of clay in quarry hills, hard to stabilize. The water comes off and into Winding Brook greenish brown. Tom and several others pushed to have the source of contamination looked into. They found that the lead and arsenic in the water came from the nearby Orchard, upslope, from legacy land uses and not the landfill. Legacy land uses like this and old gas stations consistently pose challenges for water quality, not to mention current issues.
Towns can extend their Zone II into another town. The original town must uphold strict zoning but the neighbor does not. The dep could step in but they don’t. Neponset Greenway- old railroad herbicides. Most of the time they capped but they did remove some soil. How are people allowed to build in wetlands? Golf course filled in peat wetlands, cut down trees, laid them like rafters, and built on top. Started sinking and cattails started growing in. The golf course wanted ___ State Street was just barely permitted for development by the O’Connells around 1967. Peat sinking on either side of pipes is why you get bumpy areas like that of State Street in Quincy.
What about the Baker Dam nearby? Does it play a role in water quality? Well, they looked into dredging the pcbs behind Baker dam. The sludge would go to Canada and be incinerated for $500/cubic yard. The NRWA would like to remove the two lowest dams but it’s hard to convince towns to accept federal funding by declaring the areas Superfund sites. Others like the look of the town. Norwood used to have a small pump station near Buckmaster Pond but they’re now on mwra water. They considered reopening the station but discovered that the cost of remediating the hydrocarbons from a nearby gas station was prohibitively high. (hydrocarbons were from one hundred years ago?) Route 120 sheds salt on a very sensitive area with high transmissivity (according to 1972 usgs groundwater map). Though I’ve been told by some geotechs that there’s a thin layer of clay over top of this area which would theoretically protect the groundwater from salt infiltration, salt in these soils has been steadily increasing overthe years. Solvents like __ are usually lighter than water and so they form a concentrated layer of pollution. The most common one you’ll see are oil films on parking lot puddles. How does landscape play into the transmissivity of pollutants? Willet Pond is located close to a highly transmissive piece of land but it is unlikely that it drains there due to the topography- increasing in slope- and so it flows to the southeast. This is a simple thing to point out but it brings up the ease with which a map can be misinterpreted. There isn’t a ton of sand and gravel in the area. You’ll typically see it in area of flat, low relief. Otherwise, it’s mainly till and bedrock. Traphole Brook has a lot sediment, might’ve been a part of glacial Lake Neponset. It was likely dammed and if it backed up, would’ve deposited sediment to the south (?), explaining the deposits ___. **seen the landscape change over time- Herring Runs Could access to mwra water influence development in towns? Milton doesn’t want a lot more development but Quincy is comprised of mostly renters and would appreciate more development. Canton has an emergency connection to mwra water.
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