Spooner Summit Pipeline
Incline Village General Improvement District
The Spooner Summit Pipeline Project consists of investigation and repair of three segments to the Incline Village General Improvement District’s 22-mile long secondary effluent export pipeline, including 11 miles of pipeline in the environmentally sensitive Lake Tahoe Basin. The Incline Village General Improvement District, (IVGID) exports all secondary effluent from its wastewater treatment plant at Incline Village, on the North Shore of Lake Tahoe. The effluent is pumped through a pipeline along Highway 28, over Spooner Summit and down the east slope of the Sierra Nevada Mountains to a wetlands disposal area southeast of Carson City. The pipeline was installed around 1970, and has experienced some significant leaks in all sections of the pipeline in the past few years. An initial investigation of the pipeline indicates that the pipeline interior lining system has deteriorated, with leaks most likely occurring at joints.
Kjeldsen, Sinnock & Neudeck, Inc., as surveying consultant to HDR Engineering, Inc., provided surveying and mapping services for the predesign phase of the project including establishing existing conditions topography mapping, preliminary boundary surveys, and design infill surveys for approximately 7 miles at three separate locations along the pipeline.
KSN performed a series of GPS control surveys to support the level of mapping required for the repair and replacement of the export pipeline. Significant elevation relief, dangerous highway work zones, unpredictable mountain climate, and rugged mountainous terrain along the pipeline made completing the control work within the project schedule a challenge. KSN established a complex primary control network spanning the length of the pipeline from static GPS observations, and included ties to 4 United States Coast and Geodetic benchmarks, 4 Nevada Department of Transportation control monuments, and other local control monuments. These ties referenced the final mapping to the North American Datum of 1983 (NAD 83), Nevada State Plane Coordinate System, and the National Geodetic Vertical Datum of 1929 (NGVD 29). A secondary network of 67 aerial photo control targets was established, followed by a least squares adjustment of the entire project control network.
Static GPS baselines were post-processed and both the primary and secondary control networks were adjusted by the method of least squares. Careful field procedures and data processing were utilized to ensure that survey control met or exceeded the requirements for National Mapping Accuracy Standards for 1”=50’ scale 1-foot contour mapping.
The aerial based topographic mapping was completed utilizing aerotriangulation techniques to bridge the models in the rough terrain and minimize ground surveys. This allowed for an independent QA/QC of the ground control, reduced the costs of field surveys and achieved the required National Mapping Accuracy Standards for 50-scale one foot contour design level mapping. In total, the surveying and mapping phase of the IVGID Export Pipeline Project involved the establishment of 6 GPS base stations, 67 aerial targets, and the processing of nearly 200 static GPS baselines over a length of 22 miles. Utilizing GPS technology in the field and aerotriangulation technology in the mapping process saved valuable time and allow for the project to be completed on schedule. The project highlighted the value of an expedient and accurate survey of existing conditions to a successful engineering effort. Quick delivery of the 1”=50’ scale one foot contour design level mapping for the project facilitated well-informed planning and design decisions by the engineering team, and will provide framework to help future projects preserve the beauty of the Lake Tahoe Basin. The overall budget for this project is estimated at $20 million.
This project earned KSN a Merit Award in the Surveying and Mapping Category from the Consulting Engineers and Land Surveyors of California (CELSOC).