For more information, read my Q & A with Cheryl Porter, the COO of the Great Lakes Water Authority about our drinking water below:
Where does the GLWA intake water for the system?
The Great Lakes Water Authority (GLWA) has multiple intakes throughout its system. This helps build redundancies should there be a source water issue at a specific site.
What site or sites specifically?
We do not disclose the locations of our intakes for security purposes, but all are Great Lakes sources.
Does GLWA test the water before intake to adjust the treatment process?
Yes. The GLWA conducts multiple tests not only at intake points, but throughout the entire system at various points of treatment to ensure the quality and safety of our water and treatment processes. Some of the tests taken at intake include turbidity (measurement of dirt in water), pH (the measure of how acidic/basic the water is), hardness (the amount of dissolved calcium and magnesium in the water), alkalinity (refers to the capability of water to neutralize acids), temperature, total coliforms, E. coli, algae, and toxicity. Many of these parameters help with determining the water chemistry and the adjustments that may be needed with the treatment chemicals.
Does GLWA see fluctuations in water quality and pollutants?
GLWA source water is fairly stable, although some parameters may change seasonally or after storm events. Turbidity may become elevated after a storm, windy event or during seasonal turnover. GLWA monitors source water for bacteria, algae, total organic carbon, volatile organic compounds and after treatment, for metals, pesticides, herbicides, carbamates and other parameters according to the regulatory schedule determined by EPA and MDEQ. GLWA is immediately notified when a spill is reported to the Pollution Emergency Alerting System (PEAS) that would compromise our drinking water intakes. GLWA also participates in the Lake Huron to Erie monitoring system where source water is continually monitored for targeted parameters. GLWA is also notified when treated and untreated water is discharged from a retention and treatment basin. MDEQ permit approval for treatment of marinas for algae and aquatic weeds requires notification to GLWA 48 hours in advance. This type of treatment is not allowed within 1000 feet of a water intake.
What testing does GLWA do for finding contaminates?
GLWA conducts monitoring throughout our treatment and delivery system. We monitor for contaminants throughout the drinking water system from source water to the distribution system according to the regulatory schedule determined by EPA and MDEQ. When new contaminants of concern are identified for potential regulation, GLWA participates in voluntary assessments, research and testing to determine if these contaminants are present in GLWA source waters.
Does GLWA see increases in E. coli, human waste, human blood pathogens, pharmaceuticals after heavy rains and more discharges?
GLWA water intakes were designed to not be impacted by near shore sewage pollution. Extreme increases in levels of E. coli have not been noted during heavy rains or during discharges. GLWA does not monitor for pharmaceuticals on a regular basis. During the last unregulated contaminant monitoring rule sampling events (UCMR) conducted in 2014-2015, hormones were not detected in our source waters. Perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS), and degradants were also not found in our source waters.
What chemicals are used to treat the drinking water and how are they adjusted to the quality of the water coming in?
There are various chemical additions that we use to ensure that we meet and, or surpass the regulatory agencies’ (EPA and MDEQ) standards for safe drinking water. Some of the core chemicals that are used at each plant are aluminum sulfate (used in the treatment process to coagulate small suspended particles in water), chlorine (used as a disinfectant in the treatment and distribution process), fluoride (used to prevent tooth decay) and phosphate (used for corrosion control). At Water Works Park only, Ozone is used as the primary disinfectant in the treatment process.
When GLWA treats wastewater, does it remove all solids (sludge) before discharging into the river?
Yes. Our treatment process is comprehensive, and we often return water to the environment cleaner than the water that we pump through our intake for treatment at our drinking water treatment plants.
What chemicals are used to treat the wastewater?
The chemicals we use to treat the liquid waste are: ferric chloride to remove phosphorus; chlorine to disinfect, killing disease causing bacteria; and sulfur dioxide to remove any residual chlorine. We also use chemicals to treat the solid waste. There are polymers to thicken the solids and lime for those solids transported to a landfill to reduce odors and limit attraction to insects and animals. We have facilities within the collection system that store excess wet weather flow and treat the flow if the volume is too large. Stored flows are pumped back to the system for treatment at the Wastewater Treatment Plant. These wet weather facilities use sodium hypochlorite, which is high strength bleach, to disinfect flow prior to discharge.
Is the big site in southwest Detroit the ONLY treatment plant?
Yes, our Wastewater Treatment Plant is the only wastewater treatment plant in the GLWA system, and it is also the largest in North America. There are other wastewater plants throughout the Metro Detroit region, however.
When Macomb and Oakland Counties do sewage releases rather than send it to GLWA for treatment, how much money is Detroit LOSING and they are SAVING?
Macomb and Oakland Counties have permitted treated discharges of excess wet weather flow, as you have stated. It is not a choice for Macomb and Oakland counties to send flow to their wet weather facilities rather than to the regional system. Their facilities are permitted and designed to only take the excess flow that pipes cannot accommodate. They treat and discharge the flow as prescribed by permits and operational plans as regulated by the MDEQ. Each GLWA customer is charged a “share” or percentage of the cost to run the wastewater collection and treatment system based on historic flows and the strength of the flows. Because the excess wet weather flows that are treated and discharged by Oakland and Macomb Counties do not come into the regional system, the charge structure does not consider them. As such, there is no “losing” and “saving” occurring because of these discharges.
Is this sewer water metered so the amounts can be billed accordingly?
As was stated above, our charge structure is not based directly on flow actual volumes. However, volumes are a part of the calculation of the “share” or percentage allocated to each customer. Because volumes are an important part of the “share” calculation, nearly all the sewer customers are metered. Detroit, Dearborn and Highland Park flows are not completely metered because of the large number of interconnections with the regional pipes. In these cases, hydraulic modeling, meters within the regional pipes and billing data is used to calculate volumes used in the “share” calculations.