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INDIAN RIVER COUNTY, FLORIDA MEMORANDUM TO: Jason E. Brown, County Administrator THROUGH: Richard B. Szpyrka P.E., Public Works Director Vincent Burke, P.E., Utilities Director FROM: W. Keith McCully, P.E., Stormwater Engineer Eric Charest, Environmental Compliance Specialist SUBJECT: Results of Phase 1 Water Quality Study of Nutrients in the Indian River Farms Water Control District's 8th Street Canal DATE: March 2, 2018 DESCRIPTION AND CONDITIONS The following summarizes staff's investigation of nutrients in Indian River Farms Water Control District's (IRFWCD) 8th Street Canal between 90th Avenue and 74th Avenue, as requested by the County Commission. The primary purpose of the study was to determine if suspected seepage from the County's West Regional Wastewater Treatment Facility's (WRWWTF) wetland system/deep settling pond or nearby artesian wells may be entering the canal and adding nutrients, contributing to reported excessive aquatic plantgrowth in the canal. The secondary purpose was to identify the source of any excessive nutrient loading in the canal. As discussed below, results are inconclusive. Initially, six sample locations were identified and nine water quality samples were taken from each location between September 13, 2016 and November 1, 2016. These samples (Sample Group 1) were tested for Total Nitrogen (TN), Total Kjeldahl Nitrogen (TKN), Nitrite -Nitrate Nitrogen (NOx), and Total Phosphorus (TP). Results are shown in Table 1. Because the results of the original sample sets did not allow concrete conclusions as to the source of nutrients, two additional sample sets were taken on July 20, 2017 and August 11, 2017. The second group of samples (Sample Group 2) were taken from the original sample locations and two new locations: the WRWWTF's Deep Settling Pond and a pipe discharging from private property into the canal. Figure 1 shows sample locations for both sample groups. Sample Group 2 was analyzed for NOx, Ammonia Nitrogen (NHA and Ortho -Phosphate (OP) and results are presented in Tables 2, 3, and 4. These three parameters were investigated because they are nitrogen and phosphorus components of TN and TP that are readily assimilated by plants. The analysis of Sample Group 2 is also inconclusive with respect to nutrient source, but it does indicate that WRWWTF's Deep Settling Pond / wetland system is not contributing significant quantities of nutrients to the 81h Street Canal. A summary of the entire investigation is presented in Exhibit 1, a memotitled "Results ofthe Phase 1 Water Quality Study of the IRFWCD 8th Street Canal Between 90th Avenue and 74th Avenue" Project costs to date are $3,598 for laboratory analysis. 28 C:\Users\legistar\AppData\L.ocal\Temp\BCL Technologies\easyPDF 8\@BCL@740DFDD9\@BCL@74ODFDD9.doc