KS Associates is celebrating a surveying “first.” In November 2022, our team completed the first elevation survey ever to be performed on the Cleveland Division of Water (CWD) Kirtland Crib. The Kirtland Crib is situated nearly four miles offshore in Lake Erie. It is the only water intake point for CWD’s water system that can be seen above the surface of Lake Erie. The Crib houses the five-mile tunnel that supplies water to the Kirtland Pump Station, which then pumps water to the Baldwin Water Treatment Plant.
CDM Smith hired KS Associates to perform the elevation survey. CDM Smith is designing significant structural upgrades to the Crib along with architectural, electrical, automation, and process mechanical improvements. The Crib is a critical component of Cleveland’s infrastructure, drawing millions of gallons of drinking water each day from Lake Erie.
KS surveyors enjoyed a brief boat ride to the Crib, which is approximately 3.5 miles from shore. They boarded the Crib and spent the day establishing an elevation of the structure. The elevation was based on the North American Vertical Datum of 1988 (NAVD 88) — the official vertical datum of the United States. Until KS Associates’ survey, the structure had only been referenced to Lake Erie’s approximate water level. The NAVD 88 datum provides a more reliable basis for design.
Surveyors established the elevation by positioning a Global Positioning System/Global Navigation Satellite Systems (GPS/GNSS) receiver on the Crib’s deck to establish a benchmark. Surveyors also established elevations around the structure to check its vertical plumbness.
KS Associates’ survey provided the design team with a reliable reference point. The survey will be used to compare the Crib with bathymetry of the lakebed, obtained from the National Oceanic and Atmospheric Administration’s (NOAA) Office of Coast Survey and National Ocean Service. Data from the elevation survey and NOAA gives the design team the ability to reference the structural elements of the Crib to the lakebed, as they move forward with design.
KS Coastal Engineers also performed a metocean study for the project. They calculated the wave and ice forces on the Crib to further aid in the design of its rehabilitation.