Month: June 2020

Wastewater and Covid-19 Surveillance

Screenshot of Biobot report
Report from Biobot on Livingston County, MI on Covid-19 from wastewater

Covid-19 is currently a hot topic, environmental health and engineering is no exception. Wastewater is now in international news because of it! This Reuters article from 19 June 2020 for example shows that researchers found RNA from Covid-19 in Milan and Turin’s wastewater in December 2019 before China reported the first cases on 31 December 2019! The Italian National Institutes of Health examined 40 sewage samples collected in northern Italy between October 2019 and February 2020 and found that samples in Milan and Turin from 18 December 2019 showed SARS-Cov-2. Monitoring sewage for health purposes is known as “wastewater-based epidemiology” (WBE).

Early WBE

Using wastewater to track populations is not a new idea. It was first proposed by Christian Daughton in 2001 to track illicit drug use. You can read his paper here. As a former wastewater teacher of mine, COL Timmes, liked to say: “everyone passes through us.” Generally, he meant that you can’t easily hide from the central sewage system. In more polite terms raw wastewater is a reservoir of excretion products such as: parent compounds, metabolites, and genetic material. The earliest widespread use of WBE (then called “sewage epidemiology”) was in 2005 to monitor for illicit drugs which you can find here. After this early case WBE gained traction. At least Australia, Belgium, Germany, Ireland, Italy, the Netherlands, Norway, Spain, South Korea, the United Kingdom, and the United States use WBE to monitor illicit drug use. After this initial use WBE started to take off in public health circles and WBE started to be used to track broader chemical public health indicators, for instance alcohol consumption in Norway, counterfeit medicine distribution in the Netherlands, and even tobacco use in Italy.

Environmental engineers and public health officials eventually realized that any excreted substance that has known kinetic pathways in wastewater could be used to reverse engineer the initial concentration. All these early methods focused on chemicals and were based around mass spectrometry. WBE was then and is still used to study exposure to chemicals or pollutants such as pesticides, herbicides, and flame retardants. After the sewer’s viability as a surveillance network was established, someone around 2008 realized with some work they could use quantitative polymerase chain reaction methods (qPCR) to amplify, detect, and quantify genetic material.

WBE basics

WBE’s popularity continues to increase because exclusive reliance on testing of individuals is slow, costly, and generally impractical. WBE also often serves as a disease early warning indicator because asymptomatic or prodromal individuals typically don’t get tested and there may be underdiagnosis. In cases like this WBE serves as an unbiased community prevalence estimator. This is especially true with Covid-19 whose asymptomatic period is about a fortnight. Ultimately, WBE allows near real-time cheap monitoring of health indicators such as obesity, diabetes, drug use, microbial antibiotic resistance, and disease outbreak. Its use in disease outbreaks offers particularly rich data on genetic diversity of outbreaks and phylogenic analysis can reveal viral ancestry.

In Australia, the University of Queensland has been linking census data to wastewater samples across the country to see the interrelationship between wastewater chemicals and social and economic measures of a population. Doing that opened the study of socioeconomic influences on chemical consumption. This study showed that caffeine consumption is associated with aspects of financial capability and educational attainment in Australia for instance.

WBE success

WBE is successful in sentinel surveillance providing early outbreak warnings and in determining the efficacy of public health interventions. It is remarkably sensitive at picking up infections and viral load in wastewater. For polio for instance, WBE sensitivity is estimated at about 1 case per 10,000 uninfected people. WBE also allows spatial sensitivity by moving “upstream.” WBE can detect variations in circulating strains through phylogenic analysis allowing for comparisons between region and viral genomic evolution. Another important benefit of WBE is that it enables disease prevalence gauging by circumventing individual stigmatization which can arrive from clinical diagnosis (early AIDS research for instance).

SARS-Cov-2 Simplified WBE Procedure

In general all WBE follows the same process: pretreatment, concentration, recovery, secondary concentration, then detection. Detection normally means either molecular analysis or traditional culturing. In an International Water Association (IWA) webinar on 19 June 2020 Charles Gerba, an environmental microbiologist at the Water, Energy, and Sustainable Technology Center (WEST) in the University of Arizona provided an outline of how they were testing:

  • Gather a 500 mL to 1 L sample of wastewater (grab or composite was not specified)
  • Take a 100-250 mL aliquot to process
  • Spike some samples with 229E to test efficiency
  • Store at -80°C for future analysis
  • Centrifuge to remove solids because some virus are lost to solids – in general about 100 mL would spin down to 1-3 mL
  • RT-qPCR: biomarkers (gene targets) N1, N2, N3, E229. Normally N2 and E229 are used to ensure the signal is specific enough. N1 and N3 are typically dropped

Difficulties in WBE Interpretation

WBE sounds amazing and it truly is. It has already been used successfully to track public health threats from polio to alcohol and all these achievements for a field under 20 years old. Its full potential isn’t even near realized at this point. However, there are several issues in the field. The largest is the lack of standardization and inability to compare results between testing facilities. These two factors are intrinsically linked but one will not necessarily solve the other. Another set of issues revolve around tying total loads to population numbers.

Difficulties with standardization

WBE is still a new field. It has not decided upon standards for many common procedures yet. For instance, some areas preform pre-process techniques to lower the risk of catching Covid-19 from working with SARS-Cov-2. Different pre-processing techniques such as pasteurization or filtration, will produce different signal drops.

Even the sample collection is very different. In wastewater there are typically two kinds of sampling: grab and composite. Grab sampling reflects a discrete point in time and space; composite sampling essentially is several grab samples pooled together at regular time or spatial intervals. Composite sampling is the most common in wastewater because varying flow patterns cause hydraulic surges followed by intermittent periods of low to no flow. However, that does not necessarily make it the best method for WBE.

The solids amount in the wastewater can also reduce efficacy of RT-qPCR methods; what phase to analyze (particulate or liquid) can affect results. Likewise, different inhibitors used for sample shipment may reduce the signal strength. The specific method chosen as a standard unfortunately must consider cost as well as effectiveness and test time. Likewise decontamination procedures between tests must be considered.

Difficulties with linking viral loads to population cases

Sewers undergo infiltration and inflow (i/i). Infiltration is where groundwater enters the sewer system through joints or breaks, inflow is where water is channeled into a sewer from various sources into the sewer such as downspouts. Without getting too deep, there are combined, separate, and merged sewer systems referring to surface runoff or sewage removal. Most large cities have merged systems were sewers were initially built as combined but started providing separate runoff and sewage systems. In short, a remote lab won’t necessarily have the proper infrastructural or weather contextualization to interpret the RNA signal in testing.

Another significant hurdle for disease monitoring is figuring out each disease’s excretion pattern. While it may seem reasonable that a greater number of sick people or sicker people excrete a higher viral load this is not always the case. Extrapolating the viral load to clinical cases becomes complicated. If the disease already has a well known viral shedding pattern and spread pattern with significant effort based, on where in the outbreak a disease is, you can get a correlation however it would be predicated upon many assumptions. For diseases with well defined correlations between degree of illness and viral shedding combined with disease transmission knowledge it is not possible to distinguish between one moderately sick person and two or more asymptomatic people with any degree of precision. With novel diseases only trend analysis is possible. Given the unknowns around viral shedding it becomes difficult to determine how the RNA signal drop corresponds with prevalence drops in the local community. It also becomes difficult to determine how strong the signal change needs to be to differentiate from statistical noise.

Correlating viral loads with clinically identified cases becomes even more challenging because of variable excretion rates during the infection, temporal delays, inconsistent spatial variability due to travel leading to use of multiple wastewater treatment systems, i/i, inactivation during transport, or infrequent, absent or inadequate clinical testing. Genomic instability in wastewater, sampling variability (grab/composite), and viral concentration efficiency differences compound these problems.

Where the sample was taken from, for instance from the sewage network or treatment plant, is also believed to effect viral recovery making comparisons difficult. The type of upstream user, for example domestic or industrial, will make a large difference as well. Areas with more septic systems then become harder to check. Likewise there is a divide between smaller more rural populations and larger cities; cities tend to create more normalization and may not necessarily be compared to their rural counterparts.

Practical difficulties with WBE

The best monitoring schedule at what frequency and spatial resolutions remain open questions which most likely vary across diseases. Likewise, who pays for the monitoring is an important consideration. Currently, WEST’s price list is between $350 and $1,250 per sample depending on how exactly they perform and analyze the sample. The quantification level can be tricky as well since most PCR techniques were developed for the clinical setting instead of an environmental one. There is also a privacy issue with this sort of monitoring.

Conclusions

WBE is an amazing tool for disease monitoring but is better suited to looking at trends because direct comparisons across catchments remains elusive. Since some aspects rely on data individual to specific catchments (recent precipitation, sewer condition, length of sewer and viral decay in sewer transport etc…) direct comparisons between viral loads may never really be achieved.

Further Resources

US EPA on Coronavirus in water and wastewater

Research Centers:

Papers:

  • Kitajima, M., Ahmed, W., Bibby, K., Carducci, A., Gerba, C. P., Hamilton, K. A., … & Rose, J. B. (2020). SARS-CoV-2 in wastewater: State of the knowledge and research needs. Science of The Total Environment, 139076
  • Nemudryi, A., Nemudraia, A., Surya, K., Wiegand, T., Buyukyoruk, M., Wilkinson, R., & Wiedenheft, B. (2020). Temporal detection and phylogenetic assessment of SARS-CoV-2 in municipal wastewater. medRxiv : the preprint server for health sciences, 2020.04.15.20066746
  • Venugopal, Anila, Harsha Ganesan, Suresh Selvapuram Sudalaimuthu Raja, Vivekanandhan Govindasamy, Manimekalan Arunachalam, Arul Narayanasamy, Palanisamy Sivaprakash et al. “Novel Wastewater Surveillance Strategy for Early Detection of COVID–19 Hotspots.” Current Opinion in Environmental Science & Health (2020)
  • Ahmed, W., Angel, N., Edson, J., Bibby, K., Bivins, A., O’Brien, J. W., … & Tscharke, B. (2020). First confirmed detection of SARS-CoV-2 in untreated wastewater in Australia: A proof of concept for the wastewater surveillance of COVID-19 in the community. Science of The Total Environment, 138764
  • Gracia-Lor, E., Castiglioni, S., Bade, R., Been, F., Castrignanò, E., Covaci, A., … & Lai, F. Y. (2017). Measuring biomarkers in wastewater as a new source of epidemiological information: Current state and future perspectives. Environment international, 99, 131-150
  • Xagoraraki, I., & O’Brien, E. (2020). Wastewater-based epidemiology for early detection of viral outbreaks. In Women in Water Quality (pp. 75-97). Springer, Cham

PFAS Discovery

Reenactment of the 1938 discovery of Teflon. Left to right: Jack Rebok, Robert McHarness, and Roy Plunkett
Reenactment of the 1938 discovery of Teflon. Left to right: Jack Rebok, Robert McHarness, and Roy Plunkett Photo courtesy of Hagley Museum and Library

Per- and polyfluoroalkyl substances (PFAS) are a widely used class of chemicals. You’re probably familiar with some of the popular brand names employing these chemicals such as Teflon, Gortex, and Dockers Stain Defender. As our understanding of PFAS has evolved it is becoming an emergent public health threat. This article is the first in a series serving to provide information on PFAS and it will cover their discovery. Other articles in the series will cover concern, regulation, treatment, environmental fate, contaminated sites, consumer protection, uses and provide sources for further information.

Introduction

Per- and polyfluoroalkyls substances (PFAS) are a family of synthetic substances covering over 4,700 chemicals which have a number of deleterious health effects attributed to them. As of 7 June 2020 California, Connecticut, Colorado, Minnesota, North Carolina, New Hampshire, New Jersey, and Vermont all have state health guidelines for some PFAS. New Jersey’s limits just recently started on 1 June 2020. The US Environmental Protection Agency (EPA) has established a health advisory of 70 parts per trillion of combined PFAS.  While PFAS is not directly regulated under the Toxic Substances Control Act (TSCA) it is monitored under the Significant New Use Rule (SNUR). On 20 February 2020 the EPA proposed a supplemental SNUR for PFAS.

Like most things, an exact beginning is hard to quantify. PFAS’ story could start in a letter dated 26 August 1812 when André-Marie Ampère wrote to Humphry Davy postulating the existence of fluorine, or in 1869 when Dmitri Mendelvee positioned fluorine in the periodic table. An equally rational choice would be 1886 when Henri Moissan first isolated elemental fluorine in France leading to his award of the 1906 Nobel Prize in chemistry. Another serious contender would be Thomas Midgley and A. L. Henne’s 1928 invention of Freon and other chlorofluorocarbons (CFCs) in their Fridgidaire laboratory, which at the time was a General Motor’s subsidiary. I am choosing to start PFAS’ story with Roy Plunkett’s 1938 discovery of Teflon and the birth of fluoropolymers.  

Discovery

On 6 April 1938 at the Chemours Jackson Laboratory in New Jersey Dr. Roy Plunkett discovered polytetrafluoroethylene (PTFE) by accident while researching new CFC refrigerants. While CFCs are now banned for their deleterious atmospheric effects under the Montreal Protocol, at the time they were used to replace ammonia and sulfur dioxide refrigerants which killed dozens of workers annually. PTFE is better known by its brand name: Teflon. Although CFCs are perfluorinated compounds, PTFE was the first discovered chemical in the class of Per- and polyfluoroalkyl substances.

After work on 5 April 1938, Dr. Plunkett and his assistant Jack Rebok reacted tetrafluoroethylene (TFE) with hydrochloric acid then compressed the mixture into metal cylinders and froze it overnight. The next morning on the 6th of April, Jack Rebok placed one of the cylinders onto a balance then opened the stop valve. Only 990 grams of TFE came out of a supposedly 1 kg container. Puzzled by the mass balance, Dr. Plunkett tipped the cylinder over and a white powder fell out. Then Dr. Plunkett stuck a metal wire to try and get more of the substance out. He was unable to get much out that way so eventually Jack Rebok suggested to cut the flask open.

Photo of lab notebook page where Plunkett recorded the discovery of PTFE
Photo of lab notebook page where Plunkett recorded the discovery of PTFE from Kinnane, A. (2002). DuPont: From the banks of the Brandywine to miracles of science.

In Dr. Plunkett’s article The History of Polytetrafluoroethylene: Discovery and Development he wrote:

On the morning of April 6, 1938, Jack Rebok, my assistant, selected one of the TFE (tetrafluoroethylene) cylinders that we had been using the previous day and set up the apparatus ready to go. When he opened the valve — to let the TFE gas flow under its own pressure from the cylinder — nothing happened…We were in a quandary. I couldn’t think of anything else to do under the circumstances, so we unscrewed the valve from the cylinder. By this time it was pretty clear that there wasn’t any gas left. I carefully tipped the cylinder upside down, and out came a whitish powder down onto the lab bench. We scraped around some with the wire inside the cylinder…to get some more of the powder. What I got out that way certainly didn’t add up, so I knew there must be more, inside. Finally…we decided to cut open the cylinder. When we did, we found more of the powder packed onto the bottom and lower sides of the cylinder.

Instead of ignoring the powder Dr. Plunkett started experimenting on it and discovered PTFE is highly resistant to corrosive acids, has excellent performance in extreme temperatures, and does not dissolve in solvents. This along with its slippery nature lead to DuPont sending PTFE to its central research department. However, no real commercially viable use was found for PTFE.

Ironically, World War II saved Teflon from oblivion. On its own PTFE, what Dr. Plunkett discovered, is a relatively useless polymer. It melts at around 327°C (≈620°F) and under that temperature sits in a ball of nonflowing gel. PTFE does not dissolve in anything and does not react with acids, bases, or solvents and at the time cost about $100 per pound (about $1,820 per pound or $4.02 per gram in 2020 dollars) to manufacture.

The Manhattan Project was the US effort to develop the atomic bomb and the savior of PTFE. The Manhattan Project needed corrosion resistant materials to separate U-235 from U-238 using differential diffusion of UF6. After Lieutenant General Leslie Groves heard of PTFE’s inertness, he verified it could separate U-235 from U-238. Then following LTG Groves’ request, the US Patent Office placed PTFE under a “Secrecy Order” and it was referred to only as “K-416.” Following military interest, DuPont patented PTFE in 1941 and registered the trade name Teflon in 1944.  The secrecy order lasted until 1946; by that time the Manhattan Project had paid for a great deal of research that otherwise would not have been carried out on the polymer and its manufacturing cost dropped tremendously.

Dr. Plunkett is also famous for leading DuPont’s team which added tetraethyllead (CH3CH2)4Pb to gasoline (which was phased out under the Clean Air Act) and for significant improvements to freon (a CFC refrigerant).

Brief PFAS Use Examples

The examples of PFAS extend across all facets of human life, from everyday household cookware to aerospace and electronics. PFAS’ widespread use takes advantage of its beneficial properties: chemical resistance, thermal stability, cryogenic properties, low friction coefficients, low surface energies, low dielectric constants, high volume and surface resistivities, and flame resistance. Once it was used to separate U-235 from U-238, the Manhattan Project immediately started finding other uses for PTFE. For example, PTFE was also used in the Manhattan Project in the antenna cap of proximity fuses thanks to its electrical insulating property and invisibility to Doppler radar. Fuel tank coatings used PTFE because of its resistance to low temperatures. After World War II, Teflon was turned to human well-being and started being used in catheters because of its low friction coefficient. PTFE was also used as insulation for wires and cables. It was even used during the Statue of Liberty’s renovations.  PTFE often serves as a precursor for other PFAS chemicals which were ubiquitous until their dangers were realized. PFAS are used in fire fighting foams, ski wax, stain-resistant materials (rugs, clothing, furniture, sprayable stain protectors), cookware, outdoor gear, cosmetics, shaving cream, sunscreen, shampoo, and myriad other applications.

Conclusion

While it may seem easy to villainize Dr. Plunkett for his discovery’s degradation of the environment and damage to human health it is critical to remember Dr. Plunkett in the context of this time. Early refrigerants included sulfur dioxide and ammonia; both regularly poisoned people. His contributions to tetraethyllead boosted octane levels enabling, among other things, advanced plane flight and jets. His work introduced numerous new products and processes which are widely used in medicine, refrigeration, aerosol, electronic, plastics, and aerospace. Several of his innovations are of critical importance to national defense.  There was also less awareness of the dangers of persistent chemicals to humans and the environment.

Further References

The EPA has designated Lahne Mattas-Curry as a point of contact and can be reached at mattas-curry.lahne@epa.gov

For more on the history and discovery of PFAS:

Other articles in the series include PFAS Structure

The EPA’s PFAS website is https://www.epa.gov/pfas

The EPA Long-Chain Perfluoroalkyl Carboxylate and Perfluoroalkyl Sulfonate Chemical Substances; Significant New Use Rule; Supplemental Proposal

PFAS SNUR on regulations.gov

NJ’s new PFAS rule

PFASproject.com – a group of faculty, post-doctoral scholars, graduate students, and undergraduates affiliated with the Social Science Environmental Health Research Institute at Northeastern University operating on an NSF grant

Cross Connection Control and Community Gardens

An Englewood Chicago Community Garden. Photo by Wendell Hutson
Englewood Chicago community gardens photo by Wendell Hutson

It’s not everyday cross-connection control and backflow makes community news. Recently, The Block Club Chicago indirectly wrote an article on cross-connection control and backflow prevention here which can serve to illustrate some interesting points.

The Block Club’s article is on how small community gardens are folding because Chicago recently changed some rules. The rule changes caused an increase in operational and capital expenditure for these gardens.

Since industrialization, communal gardens subdivided into individual plots have been a popular past time that help reconnect urban dwellers with food sources or escape the city for hobby gardening. In Europe these have been around for centuries. These are called “kolonihaver” in Denmark, “Schrebergarten” in Germany, “Volkstuinen” in the Netherlands, and by other names elsewhere. Some of Chicago’s lower income communities use communal gardens for increased food and nutritional security. In Chicago, the communal gardens also help to maintain city owned land that would otherwise be vacant.

Overview:

Chicago recently updated their cross-connection backflow prevention program requirements mandating reduced pressure zone device instead of the previously required atmospheric vacuum breakers. This change had two distinct consequences. The Block Club article focused on one; the dramatic increase in expenses for community gardens potentially causing several to fold. The second point not emphasized in the article was that this change also protects against backpressure instead of just back-siphonage. The existence of the Block Club’s article seems to point to poor understanding on the part of various stakeholders.

Topical Definitions:

A cross-connection is where the potable water system meets contamination which could affect the quality of the water. Various plumbing codes define cross-connections in different ways but they all generally follow the same pattern. The Uniform Plumbing Code of 2006 defines a cross-connection as:

Any physical connection or arrangement between two otherwise separate piping systems, one of which contains potable water and the other either water of unknown or questionable safety or steam, gas or chemical, whereby there exists the possibility for flow from one system to the other, with the direction offlow depending on the pressure differential between the two systems.

The American Water Works Association (AWWA) acknowledges that a cross-connection can occur between the potable water system and an environment as opposed to a piping system.

Backflow is essentially the reversal of the hydraulic gradient causing water to flow into the opposite direction. There are two chief kinds of backflow: back siphonage and backpressure. Back siphonage occurs when the potable water system experiences a pressure drop. This causes it to fall below atmospheric pressure and brings water into the system. An example of back siphonage would be a utility/janitor sink that is filled with a non-potable solution and having a main break or similar event compromise system pressure. Back pressure occurs when downstream pressure exceeds supply pressure causing water to reverse flow. Backpressure requires an external force to push back on the water supply as is the case with elevated piping. The American Water Works Association has provided two helpful diagrams to differentiate these two situations:

An example of back siphonage from AWWA
Back siphonage example from AWWA Manual 14: Backflow Prevention and Cross Connection Control Recommended Practices
An example of back pressure from AWWA
Back pressure example from AWWA Manual 14: Backflow Prevention and Cross Connection Control Recommended Practices

Backflow Prevention Devices/Assemblies are specifically manufactured plumbing designed to prohibit backflow. The term ‘device’ is typically used for non-testable backflow prevention fittings while ‘assembly’ normally refers to testable fittings. The American Society of Sanitary Engineering, the American Water Works Association, and the University of Southern California’s Foundation for Cross-Connection Control and Hydraulic Research are the main certifying agencies. It is important to note that devices and assemblies must be installed along a specific orientation; some are only allowed to be installed vertically, others only horizontally, and some in various orientations. Incorrect instillation can preclude the proper function of the assembly. There are six basic types of backflow prevention assemblies: air gaps, barometric loops, vacuum breakers (both atmospheric and pressure), double check valve assemblies, double check with intermediate atmospheric vent assemblies, and reduced pressure principle devices. The type of assembly used is based upon the degree of hazard posed by the type of cross-connection. Atmospheric vacuum breakers for instance are only effective against back siphonage and cannot prevent backflow from backpressure.

Legislative Framework:

The Safe Drinking Water Act allows the federal government to grant primacy to local authorities for the administration and enforcement of federal drinking water rules and regulations. Agencies that have primacy must have cross-connection control rules. State requirements for cross connection control programs are highly inconsistent, and state oversight is also varied.  States should have a cross connection control program that includes a process for hazard assessment, the selection of appropriate backflow devices, certification and training of backflow device installers, and certification and training of backflow device inspectors.

Discussion and Conclusions:

Recently, Chicago changed requirements for tapping fire hydrants. Previously, atmospheric vacuum breaker devices were required; now reduced pressure zone devices are.

The Block Club article allows some inferences to be made. For instance, the water used in Chicago’s gardens is unmetered and unpaid for through directly tapping fire hydrants. This water would be considered an “apparent loss” as opposed to a “physical loss” on a water audit. The article further goes onto mention that each growing season costs the garden operators about $400. This represents money which could be used to help maintain Chicago’s decaying water infrastructure. Formerly, there was an environmental department in Chicago that helped to offset these costs for low income communities. This department was cut as part of cost conservation measures. This department did not provide some sort of cost accounting metric for Chicago’s Water Utility Board.

It is surprising that Chicago ever allowed atmospheric vacuum breakers to be used for this purpose as areas which could have pesticides or fertilizers applied to it are high risk. This type of situation is one of the most common causes of backflows in the United States. Transient events such as these are notoriously difficult to determine exact societal burdens for. Acute gastrointestinal issues caused by transient events may or may not be widespread enough to be captured. However, even if acutely deleterious health effects are not apparent introduction of organic matter to chlorinated water causes chronically damaging disinfection byproducts and small amounts of pesticides which over time can lead to a dramatic disease burden. It seems that Chicago did not adequately communicate how the backflow device change serves to protect the health of those served by the water system.

However, typical backflow prevention assemblies normally cost around $300-400 for installation and about $60 for annual testing. The cost in Chicago however is $1,700 for installation and $150 for annual testing. 

In addition to benefits in the form of food and nutritional security, communal gardens also represent private citizens taking care of public lands without seeking renumeration from the state for their labor or tools. Free maintenance is a clear benefit for Chicago, although without further detailed cost benefit analysis the cost effectiveness of the strategy cannot be determined. However, the roughly $550 per year ($400 in water costs and $150 for annual testing) seems a reasonable amount for the upgrade and maintenance of communal garden-sized city plots.

Overall, the situation is at best a mixed bag. One of the key issues caused by Chicago’s action is that it removed a key source of food and nutrition from low income communities. An issue unresolved by this change is that Chicago’s water utility was not compensated for the water used. An urgent issue fixed through this change was securing the water quality provided by the utility. While greater stakeholder engagement is unlikely to have resolved these issues it could have helped assuage various stakeholder groups or opened a cost benefit dialogue accounting for the free maintenance the city received for the maintenance of these plots.

Further References: