NORTH FORK FLOATING SURFACE COLLECTOR 

CLACKAMAS RIVER, OR

Art Anderson (AA) is working with Black & Veatch and R2 Resource Consultants for the design of a floating surface collector (FSC) for a Portland General Electric (PGE) dam on the North Fork of the Clackamas River in Oregon. The Clackamas River settlement agreement requires that PGE install a 1,000-cfs FSC to attract downstream fish from the reservoir for collection and transport downstream. PGE contracted with Black & Veatch to prepare the 25% concept design, and later contracted to complete the design to the 100% level.

Throughout both phases, AA has served as Black & Veatch’s naval architecture and marine engineering subconsultant. For the 25% concept design phase, AA was responsible for defining environmental loading criteria, establishing structural criteria, preparing a preliminary structural design, estimating loading on facility alternatives, mooring/anchorage design and the preparation of all associated drawings and associated project documentation.

The drawings provided include general arrangements for multiple alternatives, the FSC’s four decks and gangway access; anchor mooring drawings; FSC structural framing plans; mechanical ballast and trim system diagram; structural and mechanical drawings for FSC screening systems; fish transport pipeline plans; and exclusion net plans.

Technical memorandums prepared as part of the project scope addressed environmental conditions, FSC loading, mooring systems, constructability trade-offs and belly tank design considerations. We were also responsible for preparing the weight estimate, hydrostatic analysis, and other trim and stability tasks.

For the Final/100% design phase, AAA continued to provide detailed naval architecture and marine engineering services. This effort includes updating the 25% design weight to include items developed during the earlier phase and keeping current the design weight estimate throughout the remainder of the project. Weight estimate reports were prepared for each of the four submittal packages in this phase. AAA also was responsible for revising the 25% intact stability calculations, preparing damage stability calculations for flooding of any two adjacent compartments, and preparing a ballasting/ dewatering sequence that demonstrates that excessive trim and/or heel does not occur during the transition from pumped-out loading condition to operating loading condition.
For this phase, AAA also provided General Arrangement drawing sheets that depict the arrangement of all decks, including equipment and outfitting. We prepared drawings that depict the structural arrangement and construction details for fabrication of the gangway float attached to the FSC, including supporting structural calculations. We also prepared 3-dimensional models of the FSC structure, gangway float, bilge and ballast piping system, and HVAC system with sufficient detail to identify and avoid critical interferences.

AAA’s responsibilities included structural and marine system design for the FSC barge. This effort included the development of 164 drawing sheets that show all arrangements and details of the FSC structure. Scantling sizes were calculated according to ABS rules. Bilge and ballast system, sounding tube and vent system, and HVAC drawings were prepared depicting all arrangements and details, and including all supporting calculations for sizing and selection. SNAME and ASHRAE standards were used in the calculation of heating and cooling loads.

Anchoring and mooring drawings were also developed by AAA, depicting the FSC’s seven mooring lines and anchors. AAA employed Optimoor software to assist in the preparation of the supporting calculations.

AAA prepared technical specifications for the FSC’s construction, which incorporated material, welding, inspection, testing, tolerance, and quality control requirements. Input was provided to update the 25% design construction costs for the FSC’s fabrication and assembly in a remote location in the vicinity of the dam, and incorporated all known assembly site development, mobilization, demobilization, and site restoration costs. During the construction procurement phase, AAA was responsible for preparing responses to RFIs and providing technical support for contractor change orders.