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HomeMy WebLinkAbout1989-11-02; Beach Preservation Committee; MinutesCARLSBAD BEACH EROSION COMMITTEE MEETING MINUTES MEETING DATE: NOVEMBER 2, 1989 The Carlsbad Beach Erosion Committee was called to order by Chairman Monroy at 6:00 P.M., Thursday, November 2, 1989, in the City Council Chambers, 1200 Elm Avenue, Carlsbad, California. Members in Attendance: Members Absent: Mario Monroy, Chairman Gary Nessim Pearl Johnson Don Jackson Dave Copley Sally Vigil Bailey Noble City Staff in Attendance: John Cahill, Municipal Projects Manager Guests in Attendance: Jack Brunton, Art Bishop, Bill Dyson: San Diego Gas & Electric Company. Dr. Scott Jenkins and David Skelley: Scripps Institute of Oceanography. Committee Consultant in Attendance: Dr. Choule Sonu: Tekmarine Incorporated AGENDA TOPICS 1. Chairman Monroy introduced the meeting minutes of September 14, 1989, which were subsequently reviewed and approved by the Committee Members. Chairman Monroy introduced Mr. Bailey Noble as the newest member of the Carlsbad Beach Erosion Committee. 2. Chairman Monroy introduced Mr. Jack Brunton of SDG&E who in turn introduced Mr. Art Bishop and Mr. Bill Dyson representing the San Diego Gas and Electric Company. Mr. Brunton thereafter introduced Dr. Scott Jenkins and Mr. Dave Skelley of the Scripps Institute of Oceanography, consultants retained by SDG&E to study Agua Meeting Minutes: November 2, 1989 Page 2 Hedionda Lagoon. Dr. Jenkins distributed copies of the September 1989 Scripps study entitled Dispersion and Momentum Flux Study of the Cooling Water Outfall at Agua Hedionda Lagoon. Dr. Jenkins thereafter made a presentation to the Committee regarding the findings in the report which concluded that the plant's discharge plume is not interfering with sediment transport and delivering suspended materials beyond the surf zone. Dr. Jenkins concluded with his belief that four (4) issues face coastal communities regarding identification and delivery of new sand sources: Recovery of sand trapped behind existing dams and reservoirs. - Mining sand from lagoons to enlarge the title prisms to pre- 1900 levels. Recovery of sand from off-shore bars near Oceanside Harbor. "Fix-it" legislation separating beach nourishment from the NEPA Act of 1974. At the conclusion of Dr. Jenkins1 presentation, Bill Dyson of SDG&E continued with a discussion of the questions asked by the Committee in their January 6 and June 28, 1989 letters. 1. Holes in Central and Eastern Basins. Mr. Dyson indicated SDG&E has been aware of the four large holes in the central and eastern basins near the bridge structures of both AT&SF and 1-5 for some time. Mr. Dyson further indicated that SDG&E has investigated the holes over a period of several years and believes them to be stable with no affect upon the adjacent bridge structures or their foundations. Mr. Dyson has obtained a copy of the original 1953 design study for Agua Hedionda Lagoon which he believes anticipated the creation of holes near the bridge structures. 2. Existing Sand Bars in Central and Eastern Basins. Mr. Dyson indicated that SDG&E believes the sand bars have been created from displaced material from the four holes, which SDG&E believes have remained relatively unchanged since they were created. Surveys of the sand bars were conducted in 1984 and 1989 showing an increase of approximately 26,000 cubic yards of material. Mr. Dyson indicated several suspected causes of this phenomenon. 3. Sand Bars Interfering with Flushing Action. Mr. Dyson indicated that the original design and actual construction of the lagoon system over 30 years ago provided for proper flushing which he indicated is evidenced by the fact that the western entrance has never closed. Mr. Dyson further Meeting Minutes: November 2, 1989 Page 3 indicated that the original design contemplated an allowable one foot over depth of dredging to accommodate the dredge machines during low tides. His conclusion is that because of the overdredging and the large water volumes at the intake jetty, the sand bars do not affect the plant's operations in terms of water flows, volumes, or velocities. SDG&E has no plans to dredge the existing sand bars. 4. Lagoon Contamination Caused by Agricultural Run-off. Mr. Dyson indicated that continual testing as a normal course of plant operations indicates that the plant itself has not in any way contributed to lagoon contamination. The SDRWQCB has concluded that the Encina Power Plant has not contributed industrial wastes to the lagoon. Rather, SDG&E's lessees along the southern and eastern areas of the lagoon are required to build and utilize run-off catch basins to ensure that no drainage spills into the lagoon from the agricultural fields. SDG&E periodically inspects the containment basins to ensure they are properly maintained and operating as designed. A side issue involves the creation of a small beach created by run-off. Mr. Dyson indicated SDG&E believes this was caused by a series of natural events including severe rainfall in the winter of 1979-80 (27 inches) which created the small run-off beach. 5. Siltation Buildup of Eastern End of the Eastern Lacroon Basin. Mr. Dyson indicated that SDG&E acknowledges this area has been silting up at an alarming rate. SDG&E soundings taken in 1978 showed an estimated volume of 120,000 cubic yards of material covering the original silt trap and moving westerly. 1984 soundings showed an estimated volume of 290,000 cubic yards of material had moved an additional 600 feet to the west. Mr. Dyson indicated that SDG&E believes this has been caused by unsupervised rapid upland erosion into the inner lagoon and onto SDG&E property. Mr. Dyson further indicated this area is now a least tern nesting site. Permits to obtain dredging and restoration of this area to its original 1953 configuration would be difficult if not impossible. 6. Length of Existing SDG&E Jetties Interfering with Littoral Drift. Mr. Dyson indicated that the original jetty design of 1953 addressed this subject and concluded that no interference would occur. Mr. Dyson further pointed to the September 1988 Scripps Study, which concluded that the existing jetties did not impact littoral drift in this area. Meeting Minutes: November 2, 1989 Page 4 Chairman Monroy thanked the SDG&E representatives for their presentation and indicated the Committee and its consultants would be considering the information and reviewing the Scripps report in detail. 3. The meeting was adjourned by Chairman Monroy at 7:55 p.m. IILL Municipal Projects Manager Secretary, Beach Erosion Committee JJC:mg Distribution: Beach Erosion Committee Members Mayor and City Council Members City Manager Assistant City Manager Community Development Director City Engineer Gary Wayne, Acting Assistant Director of Planning