Condit Dam Removal Condit Dam Removal - Access Washington

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Condit Dam Hydroelectric Project Final Supplemental EIS Table 4.6-3 Level of Service Standards for Intersections Level of Service Signalized Intersections Unsignalized Intersections Expected Delay to Minor Street Traffic A delay < 10 seconds delay < 10 seconds Little or no delay B 10 seconds < delay < 20 seconds 10 seconds < delay < 15 seconds Short traffic delay C 20 seconds < delay < 35 seconds 15 seconds < delay < 25 seconds Average traffic delay D 35 seconds < delay < 55 seconds 25 seconds < delay < 35 seconds Long traffic delay E 55 seconds < delay < 80 seconds 35 seconds < delay < 50 seconds Very long traffic delay F 80 < delay 50 < delay Even longer traffic delays Source: Transportation Research Board (2000), page 10-15 and 17-2. Using the classification of R1 (Rural Principal Arterial for SR 14 with a speed limit of 55 mph) and R2 (Rural Major Collector for SR 141 with a speed limit of 55 mph), along with Table 4.6-1, which lists the known daily traffic counts in the area, the LOS for the roadway segment can be found. Table 4.6-2 shows capacity per hour per lane. Therefore, in the pm peak hour (the worst case scenario), approximately 12 percent of the daily traffic can be attributed to that one hour. Therefore, for SR 14, SR 141, and the remaining roadways in the study area, the number of vehicles occurring in any one hour would result in an LOS A classification. Intersection Level of Service The second type of LOS calculation examines the intersection delay given the turning movements at a location. Table 4.6-3 shows the calculation for both signalized and unsignalized intersections. No existing intersection turning movement counts were available. Therefore, intersection LOS data was not calculated, although with the low traffic volumes on SR 141 in the vicinity of the project, the LOS of the unsignalized intersection with Powerhouse Road (the proposed access point for all vehicles) should operate well within established acceptable levels of service. Estimated Future Traffic Volumes The proposed demolition of the Condit Dam is expected to begin in 2008. Traffic volumes in 2008 without the addition of demolition vehicles were estimated for the study area. The 2008 traffic volumes serve as the baseline condition for examination of the effects of the proposed project. Background traffic volumes were assumed to increase one percent annually between the last available traffic count year (2003 to 2005) and beginning of demolition (2008). This growth factor was based on the average annual population and labor force growth in the local region and from historical traffic data obtained from WSDOT. The resulting am and pm peak hour volumes along SR 141, SR 14 and Powerhouse Road are shown in Table 4.6-1. Since no intersection turning movement counts were available, no intersection LOS calculations were performed. With the increase in traffic occurring in the am and pm peak hours, and the minimal traffic occurring along SR 141 currently and projected in the future, the delay to vehicles traveling on SR 141 would be minimal. 4.6-6
Condit Dam Hydroelectric Project Final Supplemental EIS Estimated Future Level of Service The LOS analysis for the projected 2008 conditions show that peak hour traffic volumes along Powerhouse Road and SR 141 will continue to experience little delay, even with the assumed growth in background auto and truck traffic. Roadway segment LOS for SR 141 will remain at LOS A for 2008 without the additional traffic associated with the removal of Condit Dam. If concrete recycling is determined to be feasible and it occurs, the roadway segment and intersection LOS for SR 141 and SR 14 would not be reduced during construction, because the change in traffic volume is so small. Parking and Demolition Site Access Currently, the demolition site(s) for the dam are difficult to access directly. Northwestern Lake is adjacent to the demolition site to the east. Powerhouse Road is a partially paved local access roadway that intersects SR 141. Traffic associated with the current operations at the dam is minimal and seasonal at best. Demolition access would be off Powerhouse Road with the possible construction of temporary access roads to staging or disposal sites. 4.6.2 Impacts Pre-Dam Removal and Dam Breaching and Removal The proposed project would affect traffic flow on roadways in the site area during construction (or demolition). During construction/demolition of the proposed project, an average of 25 workers would be employed at the site during the peak of dam removal. Approximately 75 truck roundtrips are anticipated for dam removal activities. The work is anticipated to occur from 8:00 am to 5:00 pm Monday through Friday. It is anticipated that 29,059 cy of concrete and 2,532 cy of steel-reinforced concrete material would be removed and relocated a few thousand feet upstream from the dam. Additionally, 5,100 lineal feet of wood stave flowline would be removed, stockpiled, and recycled. Further, the existing concrete surge tank (40-foot diameter, 45-foot-high steel reinforced concrete) would be disassembled and used to fill the spillway with the remainder to be recycled. All affected areas would be revegetated at the end of the project. The proposed demolition of Condit Dam would bring additional truck trips to the area during demolition. An existing portion of Powerhouse Road as well as SR 141 and SR 14 would be impacted. New access roads would be built to accommodate access to/from dam removal and staging areas. As the preferred method of disposal of the concrete, concrete recycling may occur if a suitable recycling operation is found. A scenario for this possibility is discussed under Trip Generation below. Trip Generation Construction activities for the proposed project would extend for approximately 12 months and would result in increased traffic activity in the area. Traffic delays could occur during 4.6-7
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Condit Dam Removal Final SEPA Suppl
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March 23, 2007 Dear interested part
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Condit Dam Hydroelectric Project Fi
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Appendix A Memorandum of Agreement
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Appendix C Supplemental Aquatic Res
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Agency and Organization Letters and
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Agency and Organization Letters Con
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Contents Public Meetings Response P
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Contents Individuals Individuals A-
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