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4 -sample location map). I delivered this sample. to Analytical Laboratory &~ <br />Consultants, Inc., Eugene, Oregon. The analysis report indicates a concentration of <br />arsenic in the soil of the PUD site of 7:7 mg/kg (Appendix 5 -Soil analysis report and <br />chain-of-custody form). <br />The surface water sample was collected from one site where a small stream emerged on <br />the PUD site, flowed on the surface for approximately 30 feet (Appendix 4 -sample <br />location map). This sample was taken during an extremely dry time of year <br />(approximately 100 days of no rain previous to the time of sampling). During typical <br />winter and spring wet weather conditions, water from this source flows continues. to flow <br />in existing channels and links with other stream channels on the site. I delivered the water <br />sample to Analytical Laboratory&. Consultants, Inc. for analysis. The analysis report for <br />that sample indicated the concentration of arsenic in the water was 1.04 µg/L (Appendix <br />6 -Water analysis report and chain-of-custody form). The current water quality standard <br />for arsenic is 0.0022 µg/L (Appendix 2). <br />These laboratory data clearly show the PUD site is a major source area of arsenic into <br />Amazon Creek contributing to its degraded water quality. Any increase. in runoff from the <br />PUD site will result in an increase in loading of arsenic into Amazon Creek. Although <br />some mitigation measures have the potential to reduce the quantity of arsenic loading to <br />some degree, due to the anticipated increase in stormwater runoff, interception of <br />subsurface flow, and increase an associated increase in erosion, it would be impossible <br />for these measures to completely eliminate this increase in loading to Amazon Creek. <br />Some of the proposed mitigation measures would actually increase the loading of arsenic <br />into Amazon Creek. The Geologic Hazard Assessment on Geotechnical Feasibility <br />Investigation submitted by Shannon & Willson Inc. (Nov. 29, 2006) proposes to replace <br />the existing unstable soils in the area they identified as Hazard Area B with crushed rock <br />over large angular rock- with drainage piped to the storm water system. Not only would <br />this .action increase the peak stormwater runoff, .this interception of subsurface flow <br />would certainly increase the amount of water containing arsenic to Amazon Creek. <br />Mitigation measures for developments frequently fail leading to degraded conditions „ <br />downstream (Appendix 7 -Degradation Thresholds, Stormwater Detention, and the <br />Limits of Mitigation, Booth and Jackson; 1997).. The increased runoff from the PUD site <br />would discharge an additional loading of arsenic higher than pre-development <br />concentrations directly into a portion of Amazon Creek that is currently designated as <br />"water quality limited" on the 303(d) list for this parameter. The increase in loading of <br />arsenic into Amazon Creek as a result of implementation of the Green Valley Glen PUD <br />would be a clear violation of the Clean Water Act and state water quality standards. <br />Since the laboratory reports for both soil and water samples from the PUD site clearly <br />indicate it is a source area for arsenic, the PUD application should be denied and <br />consistent with DEQ recommendations, water quality and stream flow measurements for <br />this headwater area should be taken for at least a one year period of time before any <br />further development is considered. <br />