S E P A R U L E S RCW 197-11-970 D E T E R M I N A T I O N O F N O N S I G N I F I C A N C E
DESCRIPTION OF PROPOSAL: NERC Mitigation Project.
Grant PUD is required to mitigate (via a North American Electric Reliability Corporation (NERC) Alert) for any conductor clearance issues related to operation of all 230kV transmission lines under Grant PUD control. Please see Attachment A. This requirement comes from a October 17, 2010 NERC Alert received from NERC. This alert requires that Grant PUD survey each of its 230kV transmission lines to determine conductor clearance with the ground or other ground level features. If a violation is discovered from the survey, Grant PUD will make modifications to provide 27 feet of clearance between the energized conductor and the ground.
Extract from NERC Alert:
"NERC and the Regional Entities have become aware of discrepancies between the design and actual field conditions of transmission facilities, including transmission conductors. These discrepancies may be both significant and widespread, with the potential to result in discrepancies in line ratings. The terms "transmission facilities" and "transmission lines" as used herein include generator tie lines, radial lines and interconnection facilities.
If the entity has not previously verified that the facility design, installation, and field conditions are within design tolerances when the facilities are loaded at their rating, the entity should describe its plans to complete an assessment of its facilities to verify whether the actual field conditions conform to the entity's design tolerances in accordance with its Facility Ratings Methodology. The description of the plan for how and when all transmission lines will be assessed should be submitted to NERC by December 15, 2010. NERC recommends that the entity perform its assessment using methods or technology with adequate precision to show whether the actual field conditions support the entity's facility ratings. The entity should also explain how these measurements and assessment will be accomplished and the estimated length of time to complete the activity for all applicable facilities.
During conduct of the assessment, if the entity determines that the actual conductor clearances are not within the entity's design tolerances under existing or design conditions. the entity should coordinate their findings of the assessment with their respective Reliability Coordinator and Transmission Operator. This coordination should include establishing interim mitigation plans to address the assessment findings and any actions required to maintain bulk electric system stability and reliability. Although such plans may include derating of facilities consistent with actual field conditions, consideration should be given to optimizing the overall robustness and reliability of the bulk power system during the remediation period. Additionally, the entity is encouraged to coordinate its findings and interim mitigation plans with the Regional Entity, including the timeline and prioritization to promptly reconcile the conditions (e.g., modify construction, regrade, de-energize, de-rate the line, etc.). The entity should also notify its Transmission Planner and Planning Authority of any limitation in the facility ratings due to the interim mitigation plan and update an operating instructions, procedures, SOLs, IROLs, study models and databases used to assess the system during the remediation period."
Three transmission lines were identified that have one or more clearance violations and must be corrected. These lines are: the Midway-Frenchman Hills-Potholes 230kV T-Line with 28 violations over 37 miles; Wanapum-Columbia 230kV T-Line with 2 violations over 31.07 miles; and Wanapum-Priest Rapids 230kV T-Line with 13 violations over 17 miles.
Grant PUD has conducted a detailed analysis of each of the three line routes and determined that only specific line sections or individual transmission towers will require mitigation to meet the NERC clearance requirements. Two types of mitigation will be used, depending upon the site location, property ownership and other considerations. The first mitigation method will be replacing existing lattice steel towers with taller single pole steel towers. The second method will be recontouring of the underlying ground contour. This will involve scrapping or cutting high points of the ground to achieve the required clearance. Of the 47 individual segments of transmission line identified as requiring mitigation under the three transmission lines (a, b and c) a total of 17 sites are presently scheduled for recontouring or 39.5 percent of the project while 30 sites will be mitigated using a new single steel tower to replace the old style lattice towers.
PROPONENT: Public Utility District No. 2 of Grant County, Washington
LOCATION OF PROPOSAL, INCLUDING STREET ADDRESS, IF ANY:
a. Midway-Frenchman Hills-Potholes 230kV T-Line: This line begins at the Midway Substation located in the northern _ of Section 14, Township 13 North, Range 24 EW, M, Benton County, Washington crossing the Columbia River at this location and proceeds north to Section 12, Township 15 North, Range 24 EW, M at which point the t-line turns northeast and runs to Section 27, Township 19 North, Range 26 EW, M on the north side of the I-90 corridor where the line turns east and runs into the Potholes Substation in Section 26, Township 19 North, Range 26 EW, M. This line is 37 miles long. See Attachment B.
b. Wanapum-Columbia 230kV T-Line: This line begins at the Bonneville Power Administration's (BPA) Columbia Substation located west of the intersection of Palisades Road and Highway 28 in Douglas County in Section 21, Township 21 North, Range 22 EW,M. and extends south to the Grant PUD's Wanapum Substation in Section 15, Township 16 North, Range 23 EW, M, Grant County, Washington. This transmission line spans along the lower end of Douglas Creek and across the dryland farm fields crossing southeast to Lynch Coulee and Baird Springs. At this point the line turns south and runs for 31.07 miles into the Wanapum Substation.
c. Wanapum-Priest Rapids 230kV T-Line: This line begins at the Wanapum Substation in Section 15, Township 16 North, Range 23 EW, M, Grant County, Washington. At this point the line turns south crossing Crab Creek and the Sentinel Mountains as it proceeds south to the Priest Rapids Switchyard in Section 02, Township 13 North, Range 23 EW, M, Grant County, Washington. This line is 17 miles long.
LEAD AGENCY: Public Utility District No. 2 of Grant County, Washington.
The lead agency for this proposal has determined that it does not have a probable significant adverse impact on the environment. An environmental impact statement (EIS) is not required under RCW 43.21C.030 (2)(c). This decision was made after review of a completed environmental checklist and other information on file with the lead agency. This information is available to the public on request.
o There is no comment period for this DNS.
o This DNS is issued after using the optional DNS process in WAC 197-11-355. There is no further comment period on the DNS.
6 This DNS is issued under WAC 197-11-340(2); the lead agency will not act on this proposal for 14 days from the date below. Comments must be submitted by July 21, 2011 5:00 PM Pacific Standard Time.
Responsible official: J. Darrell Pock
Position/title: Project Specialist III
Phone: (509) 754-5098
Address: P.O. Box 878
30 C St. SW
Ephrata, WA 98823
Date: Signature:______________________________________________
J. Darrell Pock, Project Specialist III
6 There is no agency appeal.
#07043/1771492
Pub.: July 8 & 14, 2011