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Mr. Mark Maloney April 21, 2008 Page 3 loads. Three additional surface runoff monitoring sites are proposed within the yard waste compost site for the spring, summer, and early fall of 2008 to help estimate the contribution of the compost site to the total phosphorus budget to Lake Owasso. The estimated cost for the additional runoff water quality monitoring at 3 locations on the compost site assuming that 10 storm events will be sampled and tested at each monitoring location is summarized in Attachment B. The costs outlined also assume that laboratory testing will be complete by a private laboratory (Braun Intertec). Laboratory costs can be reduced by about $1,200 if samples were tested by the RCPW laboratory rather than a private laboratory. The compost area is very flat. Compost that is ready to be used is typically stored on the far west side of the site and runoff from this area typically flows overland into a ditch located on the east side of Dale Street. The remainder of the compost site, with the rows of composting material, is graded to flow to the east into the Central Park East wetland in order for the runoff to receive treatment in the wetland complex which eventually discharges downstream through a structure under Dale Street. Attachment B shows the yard waste compost area as well as the general area of the proposed runoff monitoring locations for the summer of 2008. Runoff sampling will be located at the discharge locations along the perimeter of the site in the key drainage paths on the compost site. Attachment 1F shows photos of the yard waste compost site (taken in August 2007 by Barr Engineering). The proposed runoff collection system at each of the compost area monitoring sites will be similar to the surface water runoff monitoring system used by the USGS in the study Sources of Phosphorus zn Stonnwater and Street Dirt from Two Urban Residential Basins in Madison, Wisconsi~i, 1994-95 (USGS, Water Resource Investigations Report 99-4021). Attachment G is a schematic of the sampling system. A minimum of 6 storm events will be monitored from May 2008 -September 2008, and event samples will be tested for total phosphorus, total dissolved phosphorus, total suspended solids, and volatile suspended solids. When samples are collected after storm events, the sampling system will need to be flushed with deionized water. Option 2: Expected Cost.: Up to $39,373 (by Barr) Under Option 2, no runoff monitoring at the yard waste compost site would be performed during 2008. Instead, the 2008 flow and water quality monitoring data collected at Dale Street near the yard waste compost site would be reviewed. If the estimated watershed areal load of phosphorus at that location is significantly higher than the loads estimated for the rest of the Lake Owasso watershed, then the monitoring of runoff from the yard waste compost site will be performed (see description in Option 1) in 2009. Additionally, flows and water quality will be monitored in 2009 at the major inflow points to the Central Park East wetland to help quantify the sources of the phosphorus Ioad to the wetland, and ultimately, the contribution of the compost area to phosphorus loads to Lake Owasso. Option 2 completion date would be the first quarter of 2010. Since Option 2 would extend beyond the completion of the Lake Owasso UAA, a separate report would need to be generated to summarize the monitoring results and additional project management cost would be incurred. Attachments C and D outline the proposed schedule and itemized costs associated with Option 2, respectively. The figure in Attachment E shows the location of the proposed monitoring locations for 2008 as well as those associated with Option 2. P:AMpls\23 MN\62\2362946\WorkFiles\ProjectManagementAForGLWMO_04212008\Compost_Monitoring_Revised Letter Contract_April2l.doc April 21, 2008 Version