Michelle Laboy, architect/engineer

Richard Berg

Geologist | Great lakes geological coalition | Illinois Geological Survey

How important is it to understand the glacial deposits?

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.

Which are the other organizations researching in the area of urban soil mapping? How is this information shared and who can benefit from it?

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.

Scott Bishop

Registered landscape architect | Bishop Land Design | Northeastern University faculty

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?

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?

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.

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.

How does the city keep track of groundwater levels?

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.

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. 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.

Are there aquifers in and around Boston?

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.

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.