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Location of Fire Station 15 at the POLB. 

Location of Fire Station 15 at the POLB. 

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Conference Paper
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Coastal engineering studies were performed to define site and design conditions for the development of new docking facilities and a wave protection structure at Pier F in the Port of Long Beach, California. The new facilities will provide docking to a fireboat, pilot and port security boats with lengths ranging from 30 to 110 feet (9.1 to 33.5 m)....

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... Hill, 6700 E. Pacific Highway, Suite 180, Long Beach, CA 90803; PH (562) 493-8300; FAX (562) 493-8308; email: 2 CH2M Hill, 1101 Channelside Drive, Suite 200 S, Tampa, FL 33602; PH (813) 386- 1990; FAX (813) 386-1991; email: 3 Port of Long Beach, 925 Harbor Plaza, Long Beach, CA 90801; PH (562) 283-7364; FAX (562) 283-7351; email: Coastal engineering studies were performed to define site and design conditions for the development of new docking facilities and a wave protection structure at Pier F, in the Port of Long Beach, California. The new facilities will provide docking to a fireboat, pilot and port security boats with lengths ranging from 30 to 110 feet (9.1 to 33.5 m). The study showed that yearly wave conditions exceed accepted wave height criteria for small craft harbors and that wave protection would be needed. While most wave protection structures would be adequate to provide the necessary wave protection, site conditions and project requirements proved to be very challenging conditions that limited the applicability of typical structures. A floating breakwater was analyzed along with fixed structure alternatives such as rubble mound, caissons, concrete sheet and cylindrical pile breakwaters, and the preferred steel sheet/king pile breakwater. The Port of Long Beach (POLB) plans to build a new Fireboat Station No. 15 and docking facilities at Pier F that will replace outdated existing ones, where boats and docks are experiencing the adverse effects of wave agitation. These will include a boat bay for the Long Beach Fire Department (LBFD) new fireboat; docks for boats operated by the Jacobsen Pilot Service (JPS), the Long Beach Police Department (LBPD) and the POLB Security Division; a fuel station; and a hoist and platform to launch small boats and handle containers and equipment. The new facilities will improve the functionalities of the existing ones, and will provide docking to a wide range of boats with a variety of missions. The 17-boat fleet, to be docked along an approximately 800-foot (244 m) waterfront, includes a fireboat, pilot and port security boats with lengths ranging from 30 to 110 feet (9.1 to 33.5 m). Pier F is located adjacent and on the east side of the POLB main entrance channel. The 75-80-foot (22.9-24 m) deep channel passes through a narrow 900-foot (274 m) gap formed by the southern end of Pier F to the east and the Navy Mole to the west. Figure 1 shows the location of Fireboat Station No. 15 at Pier F and the Middle Breakwater sided by the San Pedro Breakwater to the west and the Long Beach Breakwater to the east. Wave conditions at Pier F are, in general, relatively benign. Waves generated within the Los Angeles-Long Beach (LA-LB) harbor by the average year-round 10- knot (5.2 m/s) southwest wind are not problematic for the boats and docks currently at Pier F. However, the typical 30+ knot (15.5 m/s) southerly (prefrontal) winds in the winter, associated to the passage of cold fronts, generate 1 to 2-foot (0.3 to 0.6 m), 2- second period waves within the harbor that are problematic for the docks and boats, in particular due to their relative broadside angle of incidence. In addition, the offshore 4 to 10-second waves generated by the prefrontal winds in the winter and the 12 to 16-second swell generated by tropical hurricanes along the Pacific Coast of Mexico during the summer penetrate through the LA-LB harbor breakwaters causing an undesirable “surging” that also affects boats and docks. In order to determine the need and type of wave protection that could potentially be necessary for the new docking facilities at Pier F, coastal engineering studies and investigations were performed. These included numerical modeling of wind waves within the LA-LB harbor, the penetration of offshore swell and long waves (infragravity), and ship and tsunami induced currents. The need for wave protection in small craft harbors is generally assessed using guidelines such those developed by the ASCE (1994) and the Permanent International Association of Navigation Congresses (PIANC, 1995) which define allowable levels of wave conditions in harbors. Table 1 shows the wave criteria per ASCE (1994) where the allowable yearly maximum wave event is 1 foot (0.30 m) for 2-second waves and 0.5 foot (0.15 m) for waves of periods greater than 2 seconds. This criteria is the same as PIANC (1995) and consistent with others found in general design guidelines for small craft harbors. In order to determine if wave protection would be necessary according to the ASCE (1994) criteria, wave conditions and frequency of occurrence at Pier F needed to be determined. Unfortunately, long-term wave measurements or hindcasts at the site were not available to perform this analysis. However, hourly wind measurements at Pier J and Pier F from April 2005 to date from the National Ocean Service’s PORTS program, and a long-term wave hindcast outside the LA-LB harbor in the vicinity of Angel’s Gate were available. In combination with numerical wave modeling these data were used to determine wave conditions at Pier F generated by winds within the harbor and those resulting from waves that penetrate through the LA-LB harbor breakwaters. Two numerical wave models were used: a) MIKE 21 FM SW, a spectral wind-wave model, was used to simulate the generation and transformation of waves due to wind within the LA-LB harbor and b) MIKE 21 BW, a Boussinesq wave model, to simulate the transformation of deep water waves to shallow water, the generation of long waves, and the penetration of these waves to the Pier F area. The PORTS’ wind records at Pier J and F allowed for the simulation of time varying wind waves within the harbor, and corresponding conditions at Pier F, that would be more realistic than those resulting from constant wind speed/direction derived from frequency tables. Pier F is exposed to the west to the POLB West Basin, which has a relatively short 2,000 m fetch; and to the LA-LB harbor to the south which has a longer, approximately 3,000 to 4,000 m fetch. Wave conditions at Pier F generated by the passage of cold fronts in the winter are of particular interest for the assessment of wave protection at Pier F. As cold fronts approach, the prefrontal wind is usually southerly, typically increasing in speed and becoming gusty. As the cold front passes the wind direction changes clockwise to settle usually in a northwesterly direction after the front has passed. The passage of the cold front typically takes 24 hours. Table 2 shows the wind wave conditions at Pier F due to the passage of selected cold fronts in the period from April 2005 to November 2011. Waves generated within the harbor by southerly prefrontal winds exceed the 1-foot (0.3 m) wave height in all cases, and at a rate of more than once per year. After the front has passed, the westerly winds generate 1-foot (0.3 m) wave heights at a rate of approximately once per year. Because boat users at Pier F also reported that swell is also problematic, the magnitude of the swell that reaches Pier F was also estimated by means of numerical modeling. Figure 2 shows the deep water wave windows and sources that affect the LA-LB harbor. Short period local seas and northern hemisphere extratropical storm swells approach the harbor from a westerly direction, while prefrontal seas, tropical storm swells and southern hemisphere extratropical ...

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