Black Rock Lock: Fitting Four Bearings

Four connections control a single chamber

Black Rock Lock is scheduled to close on 16 November 2026 for replacement of the bushings connecting its miter gates to their hydraulic cylinders. Buffalo District’s signed 9 September notice anticipates reopening on 1 March 2027. The lock has one navigation chamber, with two upper and two lower gate leaves. Each leaf has its own operating cylinder and one of the four connections covered by the replacement work. [1, 2]

The connection transfers the cylinder’s movement to the gate. Its split spherical bearing accommodates small angular movements at the cylinder eye as the ram extends and retracts. Replacing that assembly involves the pin, retaining plates, bolts and mating surfaces as well as the bearing. A supplier’s finished component enters an existing mechanical system whose dimensions and alignment must be established at the lock. ^[2]

The April procurement file records a 150-calendar-day period from notice to proceed and a maximum of 30 consecutive calendar days of installation-and-testing downtime. The later navigation notice describes a longer operating closure. The executed programme and subsequent amendments are needed to reconcile those records for a current completion or delay assessment. For planning the physical work, the April documents expose the decisions that must be settled before the cylinder is disconnected. [1–3]

Measure the assembly before committing the machining

Revised drawing SK-02 calls for line boring the cylinder rod-end eye from an indicated existing 6.250-inch opening to 6.300 inches. It also calls for line boring the gate clevis’s upper and lower lugs from nominal 4.000-inch openings to 4.125 inches. Those are drawing dimensions for the proposed work. SK-01 and the statement of work require independent field verification before fabrication or procurement. ^[2]

The two bores belong to different parts of the connection. Their relationship must let the pin, spherical bearing and retained clevis work together after assembly. SK-02 requires the bearing manufacturer’s shop drawings to show dimensions, tolerances, clearances and fit types. Its notes also require the selected pin dimension to preserve the bearing’s internal clearances after the shrink-fitting temperature returns to normal. A dimensional check therefore has to follow the component through manufacture, installation and temperature equalisation. ^[2]

Approve the field dimensions and the manufacturer’s complete fit schedule together before releasing machining. Record each of the four locations separately. A correction discovered while the gate is still coupled can be resolved through drawings and procurement; one discovered after dismantling occupies the lock outage and may require another machining or lifting operation.

The access method and gate support form one work plan

The statement of work requires a tie-back, come-along or another approved method to hold the gate when the hydraulic system is depressurised and the cylinder disconnected. Supporting calculations and documentation must be supplied as required for government review. The contractor’s work plan must identify major access equipment, such as a barge or lift, and be coordinated with its safety plan. ^[2]

These requirements make access selection part of the dismantling method. Plant must reach the connection while leaving room for the temporary restraint, the pin-removal operation and later measurement. An access platform that works for inspection may obstruct the tooling or lifting path needed for replacement. Prepare the support arrangement, equipment position and removal sequence on the same installation drawing, with a defined condition for handing the connection back to the operator.

Black Rock’s longer-term bulkhead programme addresses a different maintenance need. Buffalo District awarded Basalt International a $6.9 million design-and-fabrication contract in April 2026, with delivery expected in November 2027. The owner describes those stackable bulkheads as the means to seal the chamber ends and permit pumping dry. Their future delivery belongs to the lock’s isolation programme; the current bearing method must be planned around the access and equipment available for its own work. ^[5]

Reserve the operator and the retest window

SK-03’s acceptance procedure requires five rotation cycles in the government representative’s presence. Monitoring covers deformation, cracking or malfunction; abnormal noise, stick-slip, vibration or overheating; and movement or deformation of the bearing. Testing must stop when a listed deficiency appears, with investigation and correction before it continues. The statement of work assigns operation of the gates to a government gate operator working with the contractor. ^[2]

This puts the operator’s availability and the correction window on the same critical path as installation. Programme a readiness review before the first cycle: measured installed dimensions, alignment, final fastener condition and the required QC record. Then reserve time for a stopped test, diagnosis and another witnessed run. A programme that ends at pin installation leaves the remaining acceptance work without an allocated possession.

Markland Locks and Dam illustrates how an operating system can lose its remaining route during a repair campaign. In October 2021, while the auxiliary chamber was already closed for miter-gate repairs, a hydraulic-cylinder problem halted the primary chamber for less than 48 hours. The repair fleet already on site helped expedite that intervention. The auxiliary chamber reopened on 4 December; a further primary-chamber hydraulic repair and fleet demobilisation still required coordinated closures. ^[4]

For a single-chamber lock, the corresponding planning question is the recovery capability available during the possession. Identify who can diagnose a failed motion test, which specialist tooling remains on site, and which replacement or machining decisions would require off-site work. The Markland experience supports arranging that capability alongside the repair team; its reported recovery time belongs to that event.

IMWO original acceptance-sequence diagram based on SK-03

Build the payment file while the joint is exposed

The statement of work’s completion package includes approved preconstruction submissions, equipment shop drawings, a post-assembly QC report, field installation drawings, acceptance test reports, warranties and operation-and-maintenance information. Section 17.3 conditions final payment on the government’s acceptance of the completion submissions and additional closeout documents. SK-03 also calls for manufacturer-led training after the system is functionally complete and before final acceptance. ^[2]

Collect that evidence at each bearing. Record the measured fit while it can be checked, retain the resolved drawing revision, and close test exceptions with the witnessed result. Installation photographs need the site’s camera permission: the same statement of work requires approval through the lockmaster and district security officer. Arrange it before an exposed connection becomes inaccessible.

IMWO’s proposed handback record joins each gate location to its field measurement, approved assembly, installed QC result, witnessed cycles and outstanding closeout item. Give the operator the accepted configuration and inspection information, and give the commercial team the same record’s documentary status. That keeps the remaining work visible through the transition from mechanical installation to service and final payment.