Correspondence among

Jon, : tp Attached is a printout of lead and copper 90" percentile results since 2004. That’s as far back as they are entered in SDWIS. Rebecca offered to get you the 2000-2004 data if you want it, but our relevant actions began in about 2006. Here is a timeline of events: 1992 — DEQ notified City of lead/copper rule requirements (Dave Timm letter indicates agreement for a modified consecutive monitoring approach) 1992 — Lead action level was exceeded in first round of monitoring, appropriate follow-up activities took place 1993 — Letter from Bay City (will conduct corrosion study, want to switch to a single, consecutive system for compliance) 1996 — Desktop Corrosion Analysis recommends P04 addition, and DPH (now DEQ) concurs (deadline to install set at 12/31/97) 1996 — Letter from City requesting approval to pilot-test a switch to ferric sulfate as its primary coagulant fcarepstan control goal i is to have a finished water Chloride to Sulfate ratio of 0.6 or less based on AWWA paper and consultant’s recommendation). | cannot locate any correspondence from DEQ agreeing to this requested change, but it appears to have taken place. 1997 — March meeting notes/memo from consultant indicating that bench test results from the coagulant change were encouraging, and requesting a 6-month full scale test (which would be completed before the 12/31/97 deadline - above). I cannot locate any correspondence from DEQ agreeing to this, but the meeting notes.indicate DEQ attended the meeting, and as far as | know the City proceeded with this. 1998 — DEQ letter approves single, consecutive system for compliance monitoring 1998 — System meets action level for January-June, exceeds for July-December 1999 — System meets action level for January-June, exceeds for July-Decmeber 2000 — System meets action level for January-June, exceeds for July-December 2001 — System meets action level for both monitoring periods 2002 — System moves to reduced, annual monitoring, and meets action level 2003 — System remains on reduced, annual monitoring, and meets action level 2004 — System remains on reduced, annual monitoring, and exceeds action level 2005 — System reverts to 6-month monitoring and meets action level during both monitoring periods 2006 — System moves to reduced, annual monitoring, and exceeds action level 2006 — DEQ meets with City (11/29). City indicates that they have contacted their consulting engineer to review ’ corrosion control treatment practices. 2007 — DEQ Sanitary Survey requires City to reoptimize corrosion control due to periodic action level exceedances, with report due to DEQ 6/30/09 2009 — Corrosion control recommendations submitted to DEQ (part of the City’s Simultaneous Compliance Assessment report), DEQ met with City 12/4, consultant recommended PO4 addition and pH adjustment, DEQ concurs 2009 — December 17 letter establishes PO4 and pH adjustment as the official OCCT, set a 12/31/2011 deadline to install 2010 — December 20 Sanitary Survey confirms that the deadline to install OCCT is 12/31/2011, but gives the City two options — commit to a new raw water source (that has a stable pH) and install PO4, or commit to remain on the current. Saginaw Bay source (that has wide variations in pH and alkalinity) and install both PO4 and pH adjustment. The City ~ subsequently chose to switch to a pH-stable raw water source (per their October 25, 2010 letter to us). 2011 — PO4 treatment was installed by the deadline and was ready to begin operation; however, all parties involved agreed that hydrants should be flushed when PO4 treatment began. Due to concerns for cold weather/icing, the City xxxEND_PAGE:deq27_b170_0762_0763_1 BM 2008-1 AV EITY, CHY OF xxxEND_PAGE:deq27_b170_0762_0763_2