To: Members of the Castle Rock Water Commission
From:
Mark Marlowe, P.E., Director of Castle Rock Water
Tim Friday, P.E., Assistant Director of Castle Rock Water
Mark Billman, EHS Manager
Title
COVID in Wastewater
Body
________________________________________________________________________________
Executive Summary
Environmental surveillance of the genetic fingerprint of COVID-19 in wastewater (sewersheds) has become a hot topic during this pandemic and Castle Rock Water has explored doing this for a number of reasons. The science is there to determine the environmental presence/absence of the COVID-19 virus genetic markers, along with quantification results to inform the rise or fall of an outbreak in a community. Although the current science has shown that the viable virus is not found in human feces, and therefore is not capable of infection, some of the questions that have still persisted include: Is there COVID-19 virus in the raw wastewater? What about solids? Can I get data to better protect my wastewater workers? Does wastewater treatment kill the virus, or is it in our streams? Other questions epidemiologically related to an outbreak include: What is the extent of the COVID-19 virus spread in my community? Given the infeasibility of testing everyone for COVID-19, how do we use sewage surveillance to help with early warning, or to provide useful information to policy makers in how best to respond to a pandemic?
With these questions in mind, Castle Rock Water looked at various providers for testing and has identified Source Molecular as one of the leading testing companies that can assist with testing wastewater for the presence of COVID genetic material in wastewater. The cost for testing is $125 - $165 per sample. After discussing various options with Source Molecular, a weekly sample test for a 6-month period was recommended as a reasonable protocol for doing an initial testing program to determine trends in wastewater. The cost of this type of program would be less than $4,000.
The nature of wastewater can vary extensively over a 24-hour period and from day to day. In Castle Rock, the customer base is approximately 90% residential with many residents working from home during this pandemic. Therefore, it seems intuitive that testing wastewater will provide keen insight into the incidence and prevalence of coronavirus within the community. As people become infected with coronavirus, the virus begins shedding genetic material within the body that is excreted in fecal matter even before someone may show symptoms of the infection. In this instance, testing wastewater can be useful as a prediction tool for helping to identify when an outbreak may be happening. Trending the data may help with developing policies such as when to implement restrictions to control the rate of community spread or when to relax restrictions.
To collect a representative sample, a 24-hour, time-weighted composite sample would be collected from the sewer main just before entering the Plum Creek Water Reclamation Authority treatment facility. The sewershed could be broken down further by collecting samples at various points upstream. As a test of this type of program, one weekly sample could be collected that would represent all customers with the Town’s service area. Data would then be compiled, and we could report back periodically on what we are finding in the wastewater.
Prior to proceeding on any kind of program like this, staff would need to seek Council input and authorization. It would also be important to coordinate any effort of this type before proceeding with Douglas County, the Tri-County Health Department, the Colorado Department of Public Health and Environment, and other wastewater districts to help with trending data on a regional and/or state-wide basis and also to understand how best to utilize the data both locally and from a broader standpoint.