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<br />--,: -, <br /> <br />u; <br />C'":- <br />r:: <br /> <br />eRE <br /> <br />c <br />c. <br /> <br />October 197C <br /> <br />REVIEW OF THE BECHTEL CORPORATION REPORT ENTITLED <br />"NAVAJO GENERATING STATION CONCEPTUAL PLA...1'1NING <br />REPORT TO THE p~IZONA STATE WATER QUALITY CONTROL <br />COUNCIL AND THE U. S. DEPARTMENT OF INTERIOR," <br />DATED SEPTEMBER 1970 <br /> <br />The purpose of this report is to furnish a basis for approval and <br />adoption of the concept of returning cooling tower blowdown water from <br />the Navajo Generating Station to Lake Powell by means of a high velocity <br />jet or jets. The report deals in particular with engineering and ecolog- <br />ical aspects of this return to the lake; however, these subjects, includ- <br />ing physical biology and ecological effects of cooling water intake and <br />discharge, are not covered in this review. All data and physical des- <br />cription that follow are from the report. <br /> <br />vlater will be pumped from Lake Powell approximately 4 miles to the <br />Navajo Generating Station. The station will have 6 cooling towers, 2 <br />towers for each generating unit. The water contract with the U. S. <br />Department of the Interior stipulates that up to 34,100 af annually <br />may be withdrawn and consumed and that up to an additional 5,900 af <br />annually may be withdrawn, used in the cooling process, and returned <br />to the lake. <br /> <br />Water will be diverted at the Lake Pumping Station located on the <br />south bank of the main stem of Lake Powell. A total of 60 cfs of pump- <br />ing capacity will be provided, including spare capacity. Maximum <br />diversion is planned.to be 48 cfs based on preliminary water consump- <br />tion studies and the long-term average annual return to the lake will <br />be about 3,650 af or 5 cfs. The maximum daily return to the lake is <br />expected to be 13.3 af or 6.67 cfs. Jater contract requirements and <br />corresponding preliminary maximum design values being used are as <br />follows: <br /> <br /> Contract Design <br /> Requirement Value <br />Maximum Annual Iii thdrawal - Acre-Feet 40,000 38,200 <br />Maximum Annual Consumptive Use - <br />Acre-Feet 34,100 32,100 <br />Maximum Annual Return - Acre-Feet 5,900 5,200 <br />Maximum 24-Hour Temperature of <br />Return Flow F 90 90 <br /> <br />Salinity records indicate that total dissolved solids at the level <br />in the reservoir at the diversion pumps has ranged between 485 ppm and <br />970 ppm. Future TDS values are expected to be higher than indicated <br />by historical records. <br /> <br />Based on information in the USBR Progress Report No.4, the total <br /> <br />1. <br />