Field Office Compliance - Field Activity - 49575

Madrid Water Department - 310337294
1575 334TH ST Madrid, IA 50156
Boone County

FO 5

Activity Report
File Name File Type File Date Note
Comments
11/18/2016 -----Original Message----- From: Gastineau, Janet [DNR] Sent: Friday, November 18, 2016 4:32 PM To: 'madridwater@windstream.net' Cc: Atkinson, Tom [DNR] Subject: turbidity Mike, I have attached the template you can use to develop a calibration or turbidity monitoring protocol for your water system. Here is what else you need to know: Your system is required to conduct grab samples of the combined filter effluent (CFE) every four hours or conduct continuous monitoring according to a calibration protocol. Individual filters are required to be monitored continuously and results of turbidity monitoring must be recorded at least every 15 minutes. HOWEVER, since your system only has two filters there is a special provision that allows you to conduct continuous monitoring of the combined filter effluent (CFE) instead of continuous individual effluent turbidity monitoring--this is what you are doing. With this comes other requirements and this is where we will need to see some data recording changes made to ensure compliance with the continuous turbidity monitoring requirements. JANET GASTINEAU
11/18/2016 The following are the continuous turbidity monitoring requirements and in parentheses I have made some comments relative to your current status. (1) Monitoring must be conducted using an approved method listed in paragraph 43.5(4)“a”; (all good, you're doing this) (2) Calibration of turbidimeters must be conducted using procedures specified by the manufacturer; (your protocol should spell this out) (3) Results of turbidity monitoring must be recorded at least every 15 minutes; (this will likely take some changes by your SCADA system integrator) (4) Monthly reporting must be completed according to subrule 43.10(6) (you are and will when item (3) above gets addressed); and (5) Records must be maintained according to 43.10(7). (For this, we need to know you can get to the electronic records of the 15 minute readings that will be used for compliance reporting purposes. SCADA has to be able to identify the 15 minute readings when the raw water pumps kick on and then select the highest reading for the day and the number of readings greater than 0.3 NTU). All of this will be detailed in the inspection report. You may continue to measure your individual filter effluent quality as you have been doing but this does not need to be reported on the MOR. JANET GASTINEAU
11/18/2016 You have two other options you may also consider: 1) install turbidimeters to measure and record each individual filter effluent (and comply with continuous turbidity monitoring requirements above) AND take grab samples of the combined filter effluent turbidity every four hours the plant is operating. 2) install turbidimeters to measure and record each individual filter effluent AND the combined filter effluent (and comply with continuous turbidity monitoring requirements above). IFE record every 15 minutes and CFE can be recorded for compliance reporting at a frequency you determine--once every 15 minutes, hourly, 2 hours, or 4 hours. JANET GASTINEAU
11/18/2016 More from the same email: Mike, I dug into our archives and found some communication from 1998 about CT values. It looks like the 25,500 gallons is based on the clear well volume at 5 feet and a baffling factor of 0.4. Perry chose to select a conservative volume. At higher operating depths, there would be higher CT (all other things being equal). Generally this comes out to a T10 or treatment rate of 110 minutes based on approximately 230 gpm max daily flow. This value, 110 minutes, is then multiplied by the lowest free chlorine residual for each day to get the CT obtained value. JANET GASTINEAU
11/18/2016 From: Gastineau, Janet [DNR] Sent: Friday, November 18, 2016 4:01 PM To: 'madridwater@windstream.net' Cc: Atkinson, Tom [DNR] Subject: CT review I am concerned about the continued use of CT required values based on 9.0 pH and 10 degrees C. I imagine your water temperature is pretty consistent but there may be some seasonal changes that should be considered in the CT calculation. What should be used is the lowest measured temperature at the end of the disinfectant segment, which would be your lab tap, and the highest daily pH value measured at the same location. However, most CT tables do not have CT values for inactivation for pH greater than 9. I'm going to check with our water supply engineering section about this. I know we have other systems (like I mentioned Des Moines Water Works) with pH greater than 9, so there must be an answer. It's just that the surface water treatment rule does not have inactivation tables for pH greater than 9.0 pH so it may have been decided a long time ago in Iowa that these systems can just default to the CT inactivation look up tables for pH <9.0. An example of a look up table for CT inactivation is attached. If you look under the last box on the right (pH=9.0) and under the 0.5 log inactivation column, you'll see that's where your CT required values come from on your spreadsheet. You receive 2.5 log inactivation because you have a conventional filtration plant. JANET GASTINEAU
Compliance Tracking
Action Type Date Completed Date Comment
State of Iowa DNR Home Site Policy
Leading Iowans in caring for our natural resources
Version: 2.3.1.23706
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