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Orange County <br />Lake Orange Auxiliary Spillway Additional Services <br /> <br /> <br />Project 20P2101 9.02 / September 21, 2022 Page 2 Schnabel Engineering South, P.C. <br />“It is our understanding a replacement of the auxiliary spillway is planned for the future, estimated at <br />approximately 5-years out. The sequence of the above-mentioned recommendations should consider the <br />County’s long-term plans for both the auxiliary spillway and principal spillway intake tower structures. <br />Schnabel currently has a contract to design concrete repairs for the auxiliary spillway and the <br />replacement of sluice gates on the intake tower structure. However, Schnabel recommends that the <br />County prioritize the structural evaluation and potential repairs to the intake tower and gates with their <br />available funds because being able to drain the reservoir during a dam safety emergency are important <br />regulatory and public safety considerations.” <br /> <br />The poor condition of the intake tower observed during our 2020 inspection led to questions on the <br />suitability of the intake tower to accommodate new sluice gates. To gather more information on the <br />current condition of the intake tower Schnabel coordinated an underwater inspection of the intake tower <br />performed under contract to the Owner by In-Water and utilized ground penetrating radar (GPR) above <br />water to locate reinforcing steel within the concrete intake tower walls. The findings from the additional <br />intake tower inspection were summarized in our revised “Additional Field Investigations Letter Report" <br />dated April 5, 2020. This report included the following statement: <br /> <br />“Given the observed deteriorated condition of the intake tower, significant repairs or replacement of the <br />intake tower is recommended. However, given the extent of the repairs necessary, and the condition of <br />the existing concrete, it is anticipated that full replacement of the intake tower would be a better long-term <br />solution.” <br /> <br />Based on our conversations, we understand Orange County has decided to replace the intake tower <br />rather than perform repairs. We assume that the intake replacement work may impact the timeline <br />associated with replacement of the auxiliary spillway, and thus the current auxiliary spillway may be in- <br />use for a longer duration than previously assumed. The s cope of the auxiliary spillway concrete repairs <br />should be tailored based on the anticipated timeline of the auxiliary spillway replacement. <br /> <br />The recommendations for the auxiliary spillway from our January 2021 report were: <br /> <br />• Evaluate the materials behind the North Wall immediately downstream of the weir. This may <br />include soil boring(s), or concrete coring, to identify the material behind the wall and top of <br />rock. <br />• Address suspected voids, cracked and spalled concrete, and open joints to prevent further <br />deterioration of the concrete and extend the lifespan of the structure. <br /> <br />This proposal includes additional inspections to better understand the observed voids and other <br />deficiencies and to aid in development of auxiliary spillway repair details. <br /> <br />DocuSign Envelope ID: 94DC2E6B-A091-44C2-A636-AEC6DE85AB37