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HomeMy WebLinkAbout1984-05-29; City Council; N/A; Local Beach and Bluff Erosion Workshop120 ELM AVENUE CARCSBAD, CALIFORNIA 92008-1989 Office of the Mayor TELEPHONE: (619) 438-5599 City of Carteimb THE CITY OF CARLSBAD INVITES SOU TO A WORKSHOP CN LOCAL BEACH EROSION Tuesday, May 29, 1984 6:00 p.m. Council Chambers 1200 Elm Avenue Please cone and join a group of concerned and knowledgeable people to discuss the long and short term problems and solutions of beach and bluff erosion. We hope to see you there. R.S.V.P. 438-5561 An agenda is enclosed. COUNCIL 5-29-84 Council took no specific action but agreed to discuss ACTION: . the seaweed project on June 5, 1984, at 5:00 P.M. CITY" OF CARLSBAD BEACH EROSION WORKSHOP MAY 29, 1984 6:00 P.M. COUNCIL CHAMBERS Presentations City of Carlsbad State Department of Parks and Recreation Scripps Institute of Oceanography Corps of Engineers Beach Builders of California AGENDA Speaker Frank Aleshire City Manager Sid Willard Departmental Geologist Rinehard Flick Asst. Research Oceanographer Don Spencer Chief Shore Protection Mick Kelly General Manager Theme Introductory Slide Show Slide Show: History of Bluff Erosion in North County & departmental policy. Beach and Near-shore Processes Monitoring as Input for Potential Solutions Coast of California Storm and Tidal Wave Study Slide Show: Artificial Seaweed 7:45 P.M. 8:00 P.M. INTERMISSION DISCUSSION Invited Resource Persons: Chamber of Commerce City of Oceanside Coastal Commission Coastal Conservancy Construction Consultant Office of Assemblyman Frazee Office of Senator Craven SANDAG SDG&E State Boating & Waterways State Dept. of Parks & Recreation Wilson Engineering Bob Watson Sherilyn Sarb Ray Koons Stu Schaffer Art Bishop, Mike Dudley, Steve Davis George Armstrong Bill Fait, Bill Tippits Dexter Wilson BEACH EROSION WORKSHOP Introduction Agenda Presenters Reports on Erosion News Articles 1200 ELM AVENUE 0^98^111 TELEPHONE CARLSBAD, CA 92008-1989 • £&7 . • (619)438-5561 City of Cartefmb Welcome to the City of Carlsbad's Beach Erosion Workshop. We thank all of you for coining to participate in a "brainstorming session" of the problems and possible solutions of coastline erosion. The beaches of north San Diego County have been steadily diminishing for a number of years. People are concerned. The Army Corps of Engineers has studied the problem in Oceanside; Scripps Institute of Oceanography has been analyzing the problem in general along the county's coastline; SANDAG has formed a committee to study the county beaches. To date, no specific program for North San Diego County has been suggested. A number of preventative measures have been taken: The Corps of Engineers has received authorization to construct a sand bypass system from the Marine base small basin to Wisconsin Street. The City of Oceanside placed several hundred thousand cubic yards of sand along its beaches. Carlsbad property owners have constructed rip rap barriers to protect bluffs and have installed the experimental longard tube. San Diego Gas & Electric periodically places dredged sand along the beach, south of the Agua Hedionda lagoon inlet. The City of Carlsbad has performed emergency repairs to the bluffs where erosion has threatened Carlsbad Boulevard. These actions are individual responses to specific problems; no concerted program has been developed. Currently, there is no agreement as bo the extent of the problem, no acceptance of responsibility to resolve the problem and no coordinated effort to reach a solution. We plan to change this situation. This workshop will allow us to discuss the issues and alternative solutions. Recognizing that short term solutions may not solve long term problems, our goal is to formulate a coordinated approach involving the responsible agencies to help resolve Carlsbad's coastline problems. We hope that this "learning experience" proves fruitful and that the fruits of our efforts will benefit other coastal communities facing similar problems. c CITY CF.^ CARLSBAD BEACH EROSION WORKSHOP MAY 29, 1984 6:00 P.M. COUNCIL CHAMBERS Presentations City of Carlsbad State Department of Parks and Recreation Scripps Institute of Oceanography Corps of Engineers Beach Builders of California AGENDA Speaker Prank Aleshire City Manager Sid Willard Departmental Geologist Rinehard Flick Asst. Research Oceanographer Don Spencer Chief Shore Protection Mick Kelly General Manager Theme Introductory Slide Show Slide Show: History of Bluff Erosion in North County & departmental policy. Beach and Near-shore Processes Monitoring as Input for Potential Solutions Coast of California Storm and Tidal Wave Study Slide Show: Artificial Seaweed 7:45 P.M. 8:00 P.M. INTERMISSION DISCUSSION Invited Resource Persons: Chamber of Commerce City of Oceanside Coastal Commission Coastal Conservancy Construction Consultant Office of Assemblyman Frazee Office of Senator Craven SANDAG SDG&E State Boating & Waterways State Dept. of Parks & Recreation Wilson Engineering Bob Watson Dana Whitson Sherilyn Sarb Neil Fishman Ray Koons Richard Ledford Carol Cox Stu Schaffer Art Bishop, Mike Dudley, Steve Davis George Armstrong Bill Fait, Bill Tippits Dexter Wilson c V 1 • , Cfe OB CARLSBAD BEACH EROSION WORKSHOP MAY 29, 1984 PRESENTERS Frank Aleshire, Carlsbad City Manager, will give an overview of erosion problems in Calsbad. With the assistance of City Engineer Ron Beckman and Utilities Director Roger Greer, he will touch upon loss of sand, bluff erosion from wave action, people, water run-off, storm drains and animals, roadbed undercutting and a variety of attempted short-term solutions. Sid Willard, Staff Geologist for the State Department of Parks & Recreation, has a background in marine geology and oceanography. She has been studying bluff erosion in Carlsbad and North County for the past two years. Her presentation on the history of bluff erosion in North County will include policy information on what the State Department of Parks & Recreation will and won't do about erosion. Rinehard Flick, Assistant Research Oceanographer for Scripps Institute of Oceanography, will summarize the results of papers on "Predicted Extreme High Tides . . ." , Performance Documentation of the Longard Tube . . .", and "Extreme Sea Levels . . .", showing how the results of the work applies to proposed solutions in Carlsbad. He will stress the importance of a good monitoring program as a tool to help city officials make coastal decisions. Don Spencer, Chief, Shore Protection Section, Los Angeles District Corps of Engineers, will identify, quantify and interpret the processes of shoreline change as a basis for making sound coastal plan decisions. He will present a Coast of California and Tidal Wave Study and will address Corps of Engineers policy. Mick Kelly, General Manager, Beach Builders of California, will talk about "Non- traditional Shoreline Protection—A Concept." The company of Beach Builders has been in business for three years and is the supplier of artificial seaweed for cities such as Long Beach. WILSON ENGINEERING COASTAL STORM DRAIN STUDY City of Carlsbad April 1984 Wilson Engineering Vista, California DEXTER S. WILSON 514 E. VISTA WAY • VISTA, CALIFORNIA 92083 • (619) 758-2093 Table of Contents Page Report Summary 1 Chapter 1 Introduction / Scope and Area of Study . 4 Chapter 2 Description of Existing Facilities ... 5 Chapter 3 Bluff Erosion 38 Chapter 4 Needed Repairs 41 Chapter 5 Master Facilities 45 List of Tables Page 2-1 Summary of Subareas 6, 7 4-1 Needed Repairs to Existing Drains 43, 44 5-1 Summary of Cost for Master Drainage System . . 46, 47, 48, 49, 50 List of Figures ES-1 Coastal Storm Drain Areas . . . 5-1 through 5-4 Master Drainage Facilities . . . Page 2 At Back of Report Report Summary , The storm drains serving the beach area of Carlsbad were neither designed nor constructed systematically. Each drain collects water from a small area and carries it directly over the bluff and onto the beach. Due to the steep slope of the drains descending the bluff, drain failures cause severe erosion. If the present system of drains is not replaced, periodic failures and the concomitant erosion should be expected. This study breaks coastal Carlsbad into five separate strips, from north to south, labled Areas A through E. The Areas are shown in Figure ES-1. A discusson of each area follows. Area A Area A extends from the Buena Vista Lagoon weir on the north to Oak street on the south. In this area buildings extend from the top of the bluff to the beach area. Bluff erosion is not a major concern because nearly all the beachfront land in this area has been developed. During the winter of 1984, the city improved two of the drains in this area. All of the drains should now be adequate. The only improvements currently needed in this area are curb and gutter to eliminate nuisance puddles and provide a course for water to reach the existing drains. Area B All land adjacent to the ocean in area B is part of the state park system. Area B extends from the parking lot south of Oak Avenue to the Agua Hedionda Lagoon bridge. This area is known as the Whale Watch area. Area B contains fifteen storm drains, which are spaced closer together than those in any other area is Carlsbad. There have been many drain failures in this area and there will continue to be failures in the future. To minimize erosion, the present Area B system should be replaced with a single drain parallel to the ocean. This parallel drain would cost $572,000. To repair the existing drains to original conditions would cost $187,000. If the drains were repaired to original conditions future failures could be expected due to wave action. COASTAL STORMDRAIN AREAS Area A Area B Area C Area D Area WILSON ENGINEERING FIGURE ES-I Area C Area C, known as the Terra Mar area, extends from the power plant outlet at the south end of Agua Hedionda north to Cerezo Drain. This area contains very few storm drains and, like Area A, is developed with single family homes constructed on the bluff. The storm drains in the developed area west of Carlsbad Boulevard are adequate. However, a master drainage system is needed for the areas east of Carlsbad Boulevard and for portions of Area D (see below) which drain north through Area C. To construct a master drainage system to serve this area would cost $495,000. To repair the existing drains to original conditions would cost $7,500. Even with repairs to original conditions, future drain failures could be expected. Area D Area D extends from Cerezo Drive south to the Encinas Creek Bridge. All land adjacent to the ocean in this area is part of the State Park System. The state land has not been improved for use as a park. Beach access is difficult and, in some areas, impossible. The storm drains in this area are all old with no evidence of recent repairs. A master drainage system should be installed in this area when it is developed as a park. Eliminating the present system and replacing it with a single drain parallel to the ocean would cost $206,000. To repair the existing drains to original conditions would cost $237,500. Repairing the drains to original conditions would not prevent future failures. Some of the drains in this area serve only state park land. Area E All land in Area E adjacent to the ocean is part of the State Park System, and is entirely developed as a campground. Area E extends from Encinas Creek on the north to Batiquitos Lagoon on the south. The bluff in this area is quite high and all access to the beach from the campground is by stairs. This is the only area containing storm drains larger than 18", although it also contains many smaller undersized drains. There has been substantial erosion from some of the smaller storm drains, but the larger drains have caused little erosion. Most of the smaller drains serve only state park land. To eliminate the present area storm drains and replace them with a master drainage system would cost $1,264,000. The master drainage system for this area would require two major drains, one serving the northern half of area E and one serving the southern half. If the drains in this area were repaired to original condition it would cost $97,000 and future failures could be expected. -3- Chapter 1 Introduction / Scope and Area of Study This report evaluates the existing Carlsbad coastal storm drains, including a listing of repairs needed to existing drains, an identification of existing drainage basins, and the development of a master coastal drainage system. The area of study is bounded on the north by Buena Vista Lagoon, on the south by Batiquitos Lagoon and on the west by the ocean. The easterly boundary of the study area is set by drainage. All drainage basins which enter the ocean directly are addressed in this report. A portion of this report will also be dedicated to bluff erosion and the design of future storm drains to limit erosion. -4- Chapter 2 Description of Existing Facilities Coastal Carlsbad has been divided into five major drainage areas for the purposes of this study. These five areas were further divided into various gravity drainage subareas. The following pages describe the five major areas and provide a description of the facilities serving each subarea. Table 2-1 lists the area, outlet pipe size, 100-year storm flow and outlet pipe capacity for each of the subareas. Area A Area A extends from the weir on Buena Vista Lagoon on the north to Oak street on the south. In this area there are buildings extending from the top of the bluff to the beach area. Bluff erosion is not a major concern in this area because nearly all the beachfront land in this area has been developed. Erosion from both wave action and storm drains at times endangers structures and thus property owners in the area must take preventative measures to protect the structures. The old storm drain facilities on the roads above the bluff were inadequate. At the present time construction is underway to install new storm drains to convey water from the roads to the beach area. This, however, will not solve all the problems. The roads in this area do not have curb and gutter. After rains, the water tends to puddle along the edge of the roads and only the overflow from the puddles is able to flow along the roads and into the storm drains. The new storm drains will not improve the situation since the water still will not be able to make its way to the drains. The puddles are a consider- able nuisance in the area and we recommend that a program be developed to install curb and gutter in this area. There are approximately 25 acres in area A. The 25 acres are broken into 4 subareas and these 4 subareas are described below. A-l This subarea contains 2.7 acres. It is served by an 18" PVC (Polyvinyl Chloride) outlet pipe with 0-ring joints which was installed during the winter of 1984. One inlet serves this subarea. The pipe runs to the beach at the north end of Ocean Street, adjacent to the beach access stair- ways. The majority of this subarea has curb and gutter. A-2 This subarea contains 9.9 acres. It is served by an 18" AC (Asbestos Cement) outlet pipe which was installed during the winter of 1984. Two inlets serve this subarea. The pipe runs to the beach at Cypress Avenue. -5- TABLE 2-1 SUMMARY OF SUBAREAS * Area/Subarea * A 1 2 3 4 „ Totals * B 1 2 3 4 5 6 7 8 ~ 9 Totals « C 1 2 3 4 5* m Totals Acres 2.7 9.9 9.5 2.9 25.0 6.0 4.7 3.3 3.4 7.9 5.8 5.0 12.8 1.0 49.9 . 2.1 14.9 3.8 3.8 3.0 27.6 Flow Generated (CFS) (§2.5 CFS/Acre 6.8 24.8 23.8 7.3 15.0 11.8 8.3 8.5 19.8 14.5 12.5 32.0 2.5 5.3 37.3 9.5 9.5 7.5 Outlet Pipe Size and Type 18" PVC 18" AC 18" AC 12" CMP Varies Unknown 18" PVC 18" PVC 18" AC 18" PVC 12" CMP Overland Varies Varies Overland 18" RCP V-ditch Unknown Outlet Capacity (CFS) 26.5 26.5 26.5 . 7.9 - - - ? 26.5 26.5 26.5 26.5 7.9 _ _ _ - - - _ _ _ _ _ _ 26.5 _ _ _ - - - Undersized a Pipe Capacity /< 18" <18" <18", CAP -6- TABLE 2-1 SUMMARY OF SUEAREAS (continued) Area/Subarea at D 1 2 SP .«* 3 •m 4 5 «6 7 8•m M 9 « Totals * -E 1 2sp I 3SP 4 5 •*• f SDo r ? sp 8 I 9 sp 10 nsp * Totals Acres 12.9 7.4 1.3 .7 4.3 1.3 .9 1.3 .5 30.6 .9 2.6 1.7 14.9 2.7 3.5 4.3 37.9 1.7 69.5 1.1 140.8 Flow Generated (CFS) @ 2.5 CFS/Acre 32.3 18.5 3.3 1.8 10.8 3.3 2.3 3.3 1.3 2.3 6.5 4.3 37.3 6.8 8.8 10.8 94.8 4.3 173.8 2.8 Outlet Pipe Size and Type 18" RCP Varies Unknown 12" CMP 18" CMP 18" CMP 18" CMP 18" CMP Overland 18" CMP 8" PVC 8" PVC 24" CMP 8" CMP 8" CMP 8" PVC 24" PVC Overland 30" CMP Overland Outlet Capacity (CFS) 26.5 - - ' - ? 7.9 26.5 26.5 26.5 26.5 - - - 26.5 3.5 3.5 47.1 3.5 3.5 3.5 47.1 _ _ _ 73.6 - - - Undersized a Pipe Capacity/<18" CAP <18" <18", CAP <18", CAP <18", CAP <18", CAP <18", CAP CAP CAP CAP in this colutm indicates that the existing pipe has insufficient capacity to serve the drainage basin. <18" indicates pipe "is smaller than the minimum recommended size of 18". indicates drains that begin and end on State park land. -7- A-3 This subarea contains 9.5 acres. It is served by an 18" AC outlet pipe. This pipe was installed currently with the construction of the adjacent hotel in the 1970's. Three inlets serve this sub- area. The pipe runs to the beach at Christiansen Way, adjacent to the beach access stairway. A-4 This subarea contains 2.9 acres. It is served by a 12" CMP (Corrugated Metal Pipe) outlet pipe. This pipe was probably installed in the 1960's. One inlet serves this subarea. The pipe runs to the beach at Elm Avenue, adjacent to the beach access stairway. This drain may need replacing in five to>ten years. Area B All land adjacent to the ocean in area B is part of the state park system. This area extends from the parking lot south of Oak Avenue to the Agua Hedionda Lagoon bridge. This area is known as the Whale Watch area. There are a large number of storm drains in this area There are several generations of storm drains, some of which are abandoned. As development proceeded in this area new storm drains were installed and the old ones were either abandoned in place or utilized to carry water from smaller areas. Bluff erosion in this area is substantial. Two storm drains in this area were replaced and repaired this winter by the City when erosion threatened Carlsbad Boulevard. In this area all the drains have a very steep slope as they leave the roadbed and go over the bluff. This area also has heavy foot traffic over the slope. Both of these factors contribute to erosion in the area. Although there are a large number of storm drains in this area, there does not appear to be a uniform drainage system. Each pipe serves a small area and nearly every pipe has caused bluff erosion. This is an area which has needed and will continue to need emergency repairs as storm drains fail. A long term drainage solution is badly needed in this area. This area contains approximately 50 acres, and 9 subareas. The majority of the major drains in this area seem to have been installed concurrent with adjacent road improvements. B-l This subarea contains 6.0 acres. It is served by two separate corrugated metal pipes. One of the drains has a single inlet and serves only a small area on the west side of Ocean Street. The other drain has two inlets and serves the majority of the area. Both drains have 12" outlet pipes. The age of these pipes is undetermined. Both pipes enter the beach area from the parking lot along Ocean Boulevard -8- between Oak and Pine. Repairs are urgently needed in this subarea because one of the drains has begun to undercut the parking lot. Both drains are shown in pictures below. -9- B-2 This subarea contains 4.7 acres. It is served by a single corrugated metal pipe, but the outlet could not be found due to a heavy growth of bamboo. It has two inlets, one on each side of Pine Avenue at Carlsbad Boulevard. The age of this pipe is undetermined. Repairs are urgently needed at the outlet due to bluff erosion. The bank appears to be supported by the bamboo growth. This pipe drops to the beach at Pine Avenue. B-3 This subarea contains 3.3 acres. It was origi- nally served by a 15" RCP pipe. The outlet pipe was repaired and eroded bluff replaced in the winter of 1984. The pipe material used for replacement was PVC with 0-ring joints. This pipe has two inlets, one on each side of Walnut Avenue, and reaches the beach at an extension of Walnut Avenue. The repaired pipe is shown below. -10- B-4 This subarea contains 3.4 acres. The pipe is fed by two inlets, one on each side of Sycamore Street, and it drops to the beach at Sycamore Street. The outlet area was repaired during the winter of 1984. The outlet is shown below. B-5 This subarea contains 7.9 acres. It is served by an 18" AC outlet pipe. The pipe is fed by two inlets, one on each side of Maple Avenue, and drops to the ocean at Maple Avenue. The pipe was repaired and erosion refilled recently, as can be seen in the picture below. -11- IT v^fi^lpi^i wst5^£WK^—v,-/ -• . fe^^:-:--^f**!**«3 B-6 This subarea contains 5.8 acres. It is served by an 18" PVC pipe with O-ring joints. The pipe is fed by four inlets along the east side of Carlsbad Boulevard. The outlet pipe was repaired and erosion refilled during the winter of 1984. This pipe drops to the ocean just south of Acacia Avenue. B-7 This subarea contains 5.0 acres. It is served by a 12" CMP outlet pipe. The pipe is fed by a single inlet along Juniper Street and drops to the ocean at Juniper Street. The outlet pipe is exposed, as can be seen in the pictures below. -12- B-8 This subarea contains 12.8 acres. Storm waters flow overland and follow the east side of Carlsbad Boulevard to Agua Hedionda. B-9 This subarea contains approximately one acre. It is composed of a small strip of land along the west side of Carlsbad Boulevard. There are seven storm drains which serve this area. Although the contributing drainage area to each drain is small, there is still considerable erosion from these drains. Also, there appear to be some low spots in the Carlsbad Boulevard curb which allow water to escape over the side of the street and down the bluffs. The location, as well as a description of each drain, is listed below the following pictures of the drains. -13- B-9a Pine Avenue 10" CMP B-9b 150' south of Pine Avenue 8" CMP -14- B-9c 50' south of Sycamore 10" CMP B-9d 100' north of Maple 10" CMP -15- B-9e 50' south of Maple 3 pipes only 1 is active -16- 3-9f 50' north of Juniper 6" CMP 8-99 100' south of Hemlock 8" PVC -17- Area C Area C extends from the power plant outlet at the south end of Agua Hedionda to Cerezo Drain. This area contains very few storm drains and much of the area is similar to Area A. A large portion of Area C has been developed with' single family homes constructed on the bluff and most of the streets in this area have curbs and gutters. The undeveloped sections of this area to the north need some improvements to prevent water from running off Carlsbad Boulevard and over the bluffs. However, there does not appear to be a major erosion problem in this area. The drainage basin east of Carlsbad Boulevard which flows overland needs improvements, but the storm water flows into Aqua Hedionda and not onto the beach so there is not a bluff erosion problem. This area contains approximately 28 acres and 5 subareas. C-l This subarea contains 2.1 acres. It is served by a 15" CMP and an 8" CMP' outlet pipe. Storm water collects along the west side of Carlsbad Boulevard and flows northward. These pipes appear to have been installed with highway improvements. The outlet pipes are approximately 300' south of the power plant cooling water outlet bridge. The two outlets are pictured below. . --. • .. y^j^^pS'fl C-la 8" CMP -18- C-lb 15" CMP C-2 C-3 This subarea contains 14.9 acres. Storm water collects along the east side of Carlsbad Boulevard and flows overland to Agua Hedionda. C-4 This subarea contains 3.8 acres. It by an 18" RCP outlet pipe which was during the winter of 1984. The area is fully developed with single family is served installed it serves dwellings. The outlet pipe end of Tierra del is 100' north Oro Street. of the southern This subarea contains 3.8 acres, and is served by a broad concrete lined surface ditch. The ditch also serves as a walkway to the beach. The ditch was installed with subdivision improve- ments. The concrete surface ditch seems to serve both funtions well and the system could solve problems in other areas of the city. The area it serves is fully developed with single family dwellings. The ditch is near the north end of Shore Drive. The ditch is shown below. -19- C-5 This subarea contains 3.0 acres and is now fully developed with single family dwellings. The outlet pipe is near the southern end of Shore Drive. Area D Area D extends from Cerezo Drive south to the Encinas Creek Bridge. All land adjacent to the ocean in this area is part of the State Park System. The state land has not been improved for use as a park. Beach access is difficult and, in some areas, impossible. The storm drains in this area are all old and appear to date from the same time period. Thus, there are no abandoned drains as were prominent in area B. The storm drains in this area appear to be reaching the end of their useful life and substantial bluff erosion could occur in this area in the immediate future if improvements are not installed. -20- At the north end of this area the storm drain system is near failure. The system as it was installed conveys water across Carlsbad Boulevard and empties it on the top of the bluff. The water flows overland across the top of the bluff and enters three storm drains which carry it over the edge of the bluff. The Bluffs in this area are quite wide and the storm water appears to spread out over the bluff and not follow clearly defined paths to the three drains which convey it over the bluff. The three drains which convey water over the bluff resemble a dam spillway and carry water over the edge, but do not allow the water to erode the top of the bluff. However, wave action has eroded the bluff and the three storm drains will soon fall into the ocean. When this occurs, storm water will go over the top of the bluff, and without the pipe protecting the bluff, rapid erosion of the bluff will occur. Surprisingly, this area has not experienced much storm erosion and the overland flow system has worked. The southern end of this area has a few storm drains and they all need some repair. Storm water erosion has left some wide gullies in this area. This area contains approximately 30 acres and 9 subareas. Most of the drains in this area appear to have been installed with the highway improvements. D-l This subarea contains 12.9 acres. It is served by an 18" RCP which conveys storm water from the east side of Carlsbad Boulevard to the west side of Carlsbad Boulevard. This pipe appears to have been installed when Carlsbad Boulevard was con- structed. The subarea is almost fully developed with single family dwellings. The drain from this subarea empties onto subarea D-2 between Cerezo Drive and Manzano Drive. D-2 This subarea contains 7.4 acres. It is served by three 15" CMP outlets. The State Park System owns this undeveloped area. Storm water from both D-l and D-2 collects in area D-2 and flows overland to the three outlets. The outlets function as spillways. All three outlets are close to failure because wave erosion has eroded the bluff nearly to the inlet. When these outlets fail, severe bluff erosion will occur. Repairs are urgently needed. One outlet pipe is 100" south and one is 250" south of Cerezo Drive. The last outlet pipe is TOO1 south of Manzano Drive. Two of the outlets are shown below. -21- -22- D-3 This subarea contains 1.3 acres. The outlet pipe for this subarea is not evident from the beach. However, there is an eroded channel in the bluff providing evidence that the outlet is properly hidden under the iceplant on the bluff. This is one of the many small subareas formed by the intersection of Carlsbad Boulevard and Palomar Airport Road. The outlet pipe is 450' south of Manzano Drive. D-4 This subarea contains .7 acres. It is served by a 12" CMP outlet pipe. The pipe is fed by two inlets along Carlsbad Boulevard. This subarea is also formed by the Carlsbad Boulevard/Palomar Airport Road intersection. The outlet pipe is near the circular parking area on the southbound lanes of Carlsbad Boulevard. The outlet pipe is shown below. -23- D-5 This subarea contains 4.3 acres. It is served by an 18" CMP outlet pipe. The pipe is fed by four inlets along Carlsbad Boulevard. This is the last of the subareas formed by the intersection of Carlsbad Boulevard and Palomar Airport Road. The outlet has caused severe erosion because the pipe is broken under the old roadbed. The outlet pipe is just south of the intersection of southbound Carlsbad Boulevard with the on ramp from Palomar Airport Road. The outlet is shown below. D-6 This subarea contains 1.3 acres, and is served by an 18" CMP outlet pipe. The pipe is fed by two inlets. The outlet has caused severe erosion because the pipe is broken approximately 5' from the old roadbed. The outlet pipe is approximately 850' north of the Encinas Creek Bridge. The outlet is shown below. -24- D-7 This subarea contains .9 acres. It is served by an 18" CMP outlet pipe. The pipe is fed by a single inlet on the east side of the southbound lanes of Carlsbad Boulevard. The outlet pipe is approximately 600' north of the Encinas Creek Bridge. The end of the outlet pipe is covered with ice plant and is difficult to locate. D-8 This subarea contains 1.3 acres. It is served by an 18" CMP outlet pipe. The pipe is fed by a single inlet on the east side of the southbound lanes of Carlsbad Boulevard. The outlet pipe is approximately 350' north of the Encinas Creek Bridge. The outlet is shown below. -25- D-9 This subarea contains .5 acres. It is a minor subarea on the west side of the southbound lane of Carlsbad Boulevard. There are no storm drain improvements in this area and storm water flows overland. Area E All land in Area E adjacent to the ocean is part of the State Park System. Area E extends from Encinas Creek on the north to Batiquitos Lagoon on the south. This area is entirely developed as a campground. The bluff in this area is quite high and all access to the beach from the campground is by stairs. There are several storm drains greater than 18" in this area and also many drains smaller than 18". A storm drain smaller than 18" is not effective. There has been substantial erosion from some of the smaller storm drains, but the larger drains have caused little erosion. This area has little need for emergency repairs, but the area should have major improvements to prevent erosion in the future. -26- This area has approximately 140.8 acres and is split into 10 subareas. E-l This subarea contains .9 acres. It is served by an 18" CMP outlet pipe. The pipe is currently fed by one inlet on the west side of the southbound lanes of Carlsbad Boulevard. One pipe which continues east from this inlet, but apears to be abandoned and not in service at this time. The outlet is broken off under the old roadbed for Carlsbad Boulevard. The broken pipe has eroded under a portion of the old roadbed and caused it to collapse. The outlet pipe is 300' north of the northern end of the parking lot. The outlet is shown below. : -;-ft--:;;: -27- E-2 This subarea contains 2.6 acres. The original pipe was replaced with an 8" PVC pipe with 0-ring joints during the winter of 1984. The erosion caused by the failure of the old pipe was also filled when the old pipe was replaced. The 8" pipe is fed by a single inlet. This subarea is composed entirely of state park campground. The outlet pipe is 150' south of the northern end of the campground (Campspace 70) . The repairs are shown below. -28- E-3 This subarea contains 1.7 acres. The original pipe was replaced with an 8" PVC pipe with 0-ring joints during the winter of 1984. The erosion caused by the failure of the old pipe was also filled when the old pipe was replaced. The 8" pipe is fed by a single inlet. The subarea is composed entirely of state park campground. The outlet pipe is 550' south of the northern end of the campground (Campspace 57) . The repairs are shown below. -29- E-4 This subarea contains 14.9 acres. It is served by a 24" CMP outlet pipe. The pipe is fed by four inlets. The subarea is composed of state park campground land, a long section of Carlsbad Boulevard, and an area of vacant land on the east side of Carlsbad Boulevard. There is evidence of erosion along the pipe, but it is not as severe as the erosion along some of the smaller storm drain pipes in this area which carry far less flow. The outlet pipe is near the middle of the mobile home park on the east side of Carlsbad Boulevard (Campspace 45) . The outlet is shown below. -30- E-5 This subarea contains 2.7 acres. It is served by an 8" CMP outlet pipe. The pipe is fed by two inlets. The subarea is composed of state park campground and a small section Boulevard. The outlet pipe has lower portions of the pipe have This pipe is in need of immediate state of Carlsbad collapsed and broken away, repair. The outlet pipe is 800' north entrance (Campsite 32). The below. of the campground outlet pipe is shown -31- E-6 This subarea contains 3.5 acres, and is served by an 8" CMP outlet pipe. The subarea is composed of state park campground and a small section of Carlsbad Boulevard. The outlet pipe appears to have been repaired in the past. The current pipe is exposed and bridging long spans. The outlet pipe is approximately 350' north of the campground entrance (Campsite 12) . The outlet pipe is shown below. -32- E-7 This subarea contains 4.3 acres. The original pipe was replaced with an 8" PVC pipe with 0-ring joints during the winter of 1984. The erosion caused by the failure of the old pipe was also filled when the old pipe was replaced. The 8" pipe is fed by a single inlet. The subarea is composed entirely of state park campground. The outlet pipe is approximately 200' south of the campground entrance (at Campfire Center). The repairs are shown below. -33- E-8 This subarea contains 37.9 acres. It is served by a 24" outlet pipe. This subarea is composed of state park campground, a large section of Carlsbad Boulevard, and a very large section of undeveloped land east of Carlsbad Boulevard. The outlet pipe was recently replaced and fill placed around it. The outlet pipe is 700' south of the campground entrance (Campspace 205). The outlet is shown below. -34- E-9 This subarea contains 1.7 acres. It is no longer served by a pipe. The original pipe failed and caused a great deal of erosion. The erosion has not been repaired, but some unsightly attempts to prevent erosion are evident as seen in the picture below. The storm water now flows overland down a beach access road, approximately 1300' south of the campground entrance and 350' north of the Ponto undercrossing (Campspace 183). ^^^-^aJ^iissHs- -35- E-10 This subarea contains 69.5 acres. It is served by a 30" CMP outlet pipe. This is the largest subarea in the study. It is also the only subarea to serve land east of the railroad tracks. This subarea is composed of state park campground, a Carlsbad Boulevard, the developed undeveloped land north and south of a large portion of the trailer park railroad tracks. The outlet pipe for is undersized. However, there is no portion of Ponto area, Ponto, and east of the this subarea erosion along the outlet pipe. The lack of erosion is probably attributable to the deep grade and slight slope of the pipe through the bluff area. The outlet pipe is just south of the Ponto under- crossing (Campspace 168). The outlet is shown below. ^;:l^ifev -^M^gfJ^*-- - •• *f ^'/^ ',fc.^u?», r- -'"'••**'>• . *T^,V>J^'-' -'--. — -. ' r; -" **, .^ ** **>••»-., «^r" -36- E-ll This subarea contains 1.1 acres, and is no longer served by a pipe. The original pipe failed and has not been replaced. The storm water flows along the campground road to the corner of the maintenance yard and over the bluff. -37- Chapter 3 Bluff Erosion In surveying the storm drains along the coast, it was possible to see virtually all stages involved in the failure of a storm drain. In the Carlsbad coastal area the failure of a storm drain causes immediate erosion. Two major erosion forces, waves and storm water, plague the coast. The results of each type of erosion are easy to distinguish. When wave action erodes the bluff, the erosion is parallel to the coast. The waves undercut the bluffs and large sections fall into the ocean. This type of erosion creates higii, steep bluffs parallel to the coast line. This type of erosion proceeds more rapidly when sand is absent from the beach. Since the Carlsbad beaches have less sand each year, the wave erosion problem is increased every year. Thus, as the amount of sand has diminished, the bluff erosions due to wave action has increased. In contrast, storm water erosion of the bluffs occurs perpendicular to the coast. Water running over the bluffs rapidly erodes wide gullies and these gullies broaden and deepen as they near the beach. On a natural bluff very little water flows directly over the bluff. Storm water would be directed parallel to the coast and enter the beach area through major drainage courses. As development has occurred storm drains have been installed to collect storm water and these drains have generally taken the shortest path to the beach, which is directly over the bluffs. These storm drains have periodically failed, substantially increasing bluff erosion. Most of the storm drains along the beach can be described as follows: The slope of the drains is generally slight as the drain approaches the bluff. At the bluff a sharp bend is installed, with a very steep section of pipe down the bluff. An outlet structure is then installed on the end of the pipe at the bottom of the bluff. There are a number of reasons why a storm drain may fail, but the following summarizes the general steps in the failure of a storm drain. 1. The outlet of the storm drain is plugged, moved, or both, by wave action causing the joints to 2. Storm water escapes from the leaky joints and rapidly erodes the steep fill around the pipe. 3. The erosion undermines the pipe, eventually causing the pipe to collapse. -38- , 4. Storm water from the collapsed pipe erodes a wide, deep gully where the storm drain used to be. There are a number of preventative measures which can reduce storm drain failures and the associated erosion. The long-term solution is to create a master system of coastal drains which collect all of the existing local drains and convey the water parallel to the coast and into major drainage channels. A long term plan is developed, and estimated costs provided, for this type of system in Chapter 5. If the master system is not installed there are a number of measures that can be taken to reduce the failure rate of the existing storm drains. These preventative measures are listed below. 1. Existing outlets can be protected from wave action. This can be accomplished by a number of mechanisms, but care must be exercised to construct an outlet which will not be easily blocked. Replacement of lost beach sand is one method of protecting outlets. Another method is to locate outlets higher up the slope away from wave action. However, if the outlet is above the beach level a concrete structure or rip-rap will need to be placed at the outlet to prevent scour and erosion at the outlet. 2. Since an integral step in the failure of a storm drain involves the joints, install storm drain piping with water tight joints. Most of the storm drains installed in the past were corrugated metal. Corrugated metal pipe does not have water tight joints. PVC piping with water tight 0-ring joints would greatly reduce joint leakage. 0-ring joints would most likely remain watertight despite slight movement of the outlet structure. Thus, 0-ring joints would reduce joint leakage and thus bluff erosion. However, if PVC pipe is installed periodic inspections will be needed to check for exposed pipe sections. PVC decomposes when exposed to sunlight. 3. Storm drain piping grade should be reduced and its depth increased. One of the major contributing factors to the storm drain bluff erosion is the steep grade of the drains. Water flowing down a steep slope will carry more material with it than water flowing down a slight slope. Thus, if the drains were installed with a level invert through the bluff area and the steep slope was moved away from the beach, the erosion potential would be reduced. There is one large corrugated metal -39- w drain installed in this manner and it appears to have functioned without causing bluff erosion for a number of years, while other storm drains which appear to have been installed at the same time have failed. 4. Inlets should be located to prevent water from going over the bluff when storm drain inlets are plugged. When new inlets are installed or old ones replaced or relocated they should be placed to prevent water from going over the bluff when inlets are plugged. Some of the existing inlets are placed such that when they plug the water goes directly over the bluff with little ponding. These should be relocated such that major ponding occurs so that maintenance crews can be alerted to the ponding and clear the drain. If ponding does not occur the drain may remain clogged for a long period of time, since no one would alert the city that it was plugged. 5. Storm drain systems should be analyzed to determine what will occur should the outlet become plugged. All storm drain piping systems should be designed to withstand the hydrostatic pressure when an outlet is plugged. A failure analysis should be conducted to see what will occur when outlets are plugged. When the outlet is plugged the storm water should pond to alert maintenance crews that there is a problem. If the joints will not hold the hydrostatic pressure the storm water will escape through the joints when the outlet is plugged and cause bluff erosion. The inlets should be located such that storm water will pond and not escape over the bluff. 6. In areas where it is impossible to relocate inlets to allow ponding and storm drain blockage will lead to water going over the bluff, surface drains should be considered. Surface drains would also provide pathways to the beach and help to mitigate erosion caused by beach users. 7. Storm drains should have a minimum size of 18". Many of the storm drain failures, especially in the state park campground, have occurred in the undersized drains. Virtually all of the 8" drains in the campground have failed. Also, the erosion caused by the failure of small drains is as severe as that caused by larger drains. -40- Chapter 4 Needed Repairs Chapter 5 provides an estimate of the costs to construct a master storm drainage system which would eliminate nearly all of the present outlet pipes to the ocean. If the master storm drainage system is constructed, many of the repairs listed in this chapter may not be needed and those which are needed may be less costly if temporary repairs are made. If the master drainage system proposed in Chapter 5 is not adopted, then all listed repairs should be made. The repairs should be done in accordance with the recommendations in Chapter 3. There are a number' of storm drains identified in this study needing repair. This study splits the drains into two cate- gories. The first category contains drains urgently needing repairs, where erosion will soon undercut roadways or improved parking lots. Also included in this category are drains which will soon fail and have the potential for substantial natural bluff erosion. The second category consist of drains needing repairs to restore the drains to original condition and prevent further erosion, but the repairs are not as urgent as the repairs noted in the first category. Included in the second category are drains which have undercut the old Highway 101 roadbed in areas where it is used as an unimproved parking lot. The repairs have also been divided into two groups by land ownership. All drains which begin and end on state park land are listft^separately. Urgent Repairs; City of Carlsbad Drains B-l The northern drain in this drainage basin is beginning to undercut the parking lot. If repairs are not made, areas of the lot may collapse. The CMP pipe should be replaced with PVC pipe and the erosion refilled. The estimated cost for repairs is $15,000. B-2 The pipe which serves this area has eroded the bluff and will soon begin to undercut the parking lot on the end of Ocean Street. The large growth of bamboo is slowing erosion, but this drain should be repaired and the erosion filled. The estimated cost for these repairs is $10,000. -41- Urgent Repairs; State Park Drains D-2 The three drains which serve this area should be reconstructed. The drains will soon collapse, leaving the bluff unprotected. Storm water will cause rapid erosion on the unprotected slopes. The estimated cost for these repairs is $50,000. E-5 The pipe which serves this area has failed and will rapidly erode the bluff. The drain should be replaced and the slope refilled. The estimated cost for repair is $37,500. Other Needed Repairs There are a large number of drains which need to be repaired. Most of the drains need to be refilled and new pipe installed. Table 4-1 lists the drains and needed repairs. The table lists City of Carlsbad Drains separately from State Park area Drains. Most of the money needed to fix these drains could be better spent on the needed master facilities. The cost presented are to restore the drains to their original condition. The drains should be expected to fail again, since the original installation has failed. Many of the drains in the state park campground are under- sized and should be replaced. However, the need for each of these repairs should be judged independently, remembering that the master facilities recommended in the next chapter would eliminate the need for these repairs. -42- TABLE 4-1 NEEDED REPAIRS TO EXISTING DRAINS CITY OF CARLSBAD DRAINS * - *• «M <m m "* m * m ••m m £» Drain D-5 E-l B-9g D-6 E-4 B-7 B-9a B-9b V9c •«•**&*'B-9d D-3 D-4 D-7 D-8 B-9f C-l B-5 B-9e Description of Repairs Replace pipe, refill and rock outlet Replace pipe, refill and rock outlet Refill pipe, rock outlet Replace pipe, refill and rock outlet Refill pipe, rock outlet Replace pipe with 18", refill and rock around outlet Refill pipe, rock outlet Refill pipe, rock outlet Replace pipe, refill and rock outlet Refill pipe, rock outlet Locate pipe and repair Replace pipe, refill and rock outlet Replace pipe, refill and rock outlet Replace pipe, refill and rock outlet Refill and rock around outlet Refill both pipes Refill and rock around outlet Refill and rock around outlet Cost $ 37,500 37,500 15,000 37,500 22,500 37,500 15,000 15,000 37,500 15,000 37,500 37,500 22,500 15,000 12,000 7,500 7,500 7,500 Subtotal $417,000 'im -43- TABLE 4-1 NEEDED REPAIRS TO EXISTING DRAINS a (continued) STATE PARK DRAINS Drain <* E-6 , E-9 « E-ll E-2b E-3b - E-7b Description of Repairs Replace pipe with 18", Remove debris, refill, Remove debris, refill, Replace pipe with 18", Replace pipe with 18", Replace pipe with 18", '** «. refill and rock outlet improve road drain improve road drain refill and rock outlet refill and rock outlet refill and rock outlet Cost $ 37,500 30,000 22,500 37,500 37,500 37,500 Subtotal $202,500 TOTAL - $619,500 a Drains are listed with those needing repairs the most first. These drains have recently been repaired. They are listed as needing repairs because the new pipe is 8" and the minimum storm drain size should be 18". -44- Chapter 5 Master Facilities Figures 5-1 through 5-4 show the Master Facilities needed to collect storm water and convey it parallel to the coast and reduce the bluff erosion caused by storm water. Each area will be discussed below and improvements recommended. Table 5-1 summarizes the recommended improvements. A description of each pipe reach as well as cost information may be found to this table. Area A The existing drains in this area are adequate and no new facilities are planned for this area. The area is fully developed and the existing drains, upon failure, would cause more damage to improvements in the area than to the bluff. The only improvements needed to this area are curb and gutter to eliminate the nuisance puddles. Area B - Whale Watch Area A storm drain should be constructed in Carlsbad Boulevard, beginning at Pine Avenue and continue south to Agua Hedionda. The drain will vary in size from 24" to 48". The approximate length of the needed improvements is 4,290'. The estimated cost for these improvements is $572,000. Table 5-1 summarizes the needed improvements. We looked at the alternative of installing two pipelines to serve this area. One would start at Sycamore and flow north, the other would start at Maple and flow south. This alternative was slightly more expensive, but it should be reevaluated during final design if master facilities are constructed in this area. The proposed facilities are quite deep and the alternate of two drains eliminates some of the deep sections of storm drain. The westerly curb of Carlsbad Boulevard should also be raised to prevent storm water from going over the curb. Also, drainage patterns in the Whale Watch area should be reviewed to make sure the storm water does not go over the bluff. It appears that curb breaks for handicapped persons may have re-routed some of the storm water flows. Area C - Terra Mar Area A storm drain is needed as the majority of the storm water will come from the developed area east of Carlsbad Boulevard. The drain should begin in Area D just south of Cerezo Drive and continue north to Agua Hedionda. The developed area west of Carlsbad Boulevard would not be served by this new storm drain. This area would continue to be served by the existing drains. -45- TABLE 5-1 SUMMARY OF COST FOR MASTER DRAINAGE SYSTEM Contributory Subareas Whale Watch Area (Flows South) B-l B-l - B-2 B-l thru B-3 B-l thru B-4 B-l thru B-5 B-l thru B-6 B-l thru B-7 B-l thru B-9 Location & Description of Improvements Ocean St. North of Pine Ave. 230' of 24" Carlsbad Blvd., Pine Ave. to Walnut Ave. 540' of 30" Carlsbad Blvd. , Walnut Ave. to Sycamore Ave. 2201 of 36" Carlsbad Blvd. , Sycamore Ave. to Maple Ave. 630' of 36" Carlsbad Blvd., Maple Ave. to 140' So. of Acacia Ave. 470' of 42" Carlsbad Blvd. , 140' So. of Acacia Ave. to Juniper Ave. 550' of 48" Carlsbad Blvd., Juniper Ave. to Tamarack Ave. 850' of 48" Carlsbad Blvd. , Tamarack Ave. to Agua Hedionda Lagoon 800' of 48" Total Acres Served 6.0 10.7 14.0 17.4 25.3 31.1 36.1 49.9 Approximate Flow Line Depth (feet) 8 13 17 19 21 24 22 10 Costs (Thousands of Dollars) a 15 46 23 66 71 94 . 145 112 •m m Subtotal 572 -46- TABLE 5-1 SUMMARY OF COST FOR MASTER DRAINAGE SYSTEM (continued) Contributory Subareas Terra Mar Area (Flows North) D-l, D-2 D-l, D-2 and C-2 D-l, D-2 C-2 & C-l Location ft Description of Improvements Carlsbad Blvd., 470' So. of Cerezo Dr. to Cannon Road 2,150' of 42" Carlsbad Blvd., Cannon Rd. to 650' No. of Power Plant Outlet 1,800' of 48" Carlsbad Blvd., 650' No. of Power Plant Outlet to Agua Hedionda Lagoon 3501 of 48" Total Acres Served 20.3 35.2 37.3• Approximate Flow Line Depth (feet) 9 9 5 Costs (Thousands of Dollars) a 226 225 44 Subtotal 495 Palomar Airport Rd. to Encinas Creek (Flows South) D-3 D-3 & D-4 D-3 thru D-5 Southbound Carlsbad Blvd. 900' South of Manzano Dr. to just North of paved loop adjacent to South- bound lanes of Carlsbad Blvd. 350' of 18" Southbound Carlsbad Blvd. just North of paved loop to end of Palcmar Airport Road onramp. 500' of 18" Southbound Carlsbad Blvd. end of Palomar Airport Rd. onramp to 800' South of onramp. 800' of 24" 1.3 2.0 6.3 11 13 19 30 52 -47- TABLE 5-1 SUMMARY OF COST FOR MASTER DRAINAGE SYSTEM (continued) Contributory Subareas Location & Description of Improvements Total Acres Served Approximate Flow Line Depth (feet) Costs (Thousands of Dollars) a Palomar Airport Rd. to Encinas Creek (Flows South)(con't) D-3 thru D-6 D-3 thru D-7 D-3 thru D-9 Southbound Carlsbad Blvd. 800' South of onramp to 1,160' North of Encinas Creek Bridge 430' of 27" Southbound Carlsbad Blvd. 1,160' North of Encinas Creek Bridge to 650' North of Bridge. 510' of 27" Southbound Carlsbad Blvd. 650' North of Encinas Creek Bridge to Bridge. 650' of 27" 7.6 12 30 8.5 33 10.3 42 Subtotal 206 Northern Part of State Park Campground (Flows North) E-5 Southbound Carlsbad Blvd. Campspace 32 to Campspace 45 . 800' of 18" 2.7 44 -48- TABLE 5-1 SUMMARY OF COST FOR MASTER DRAINAGE SYSTEM (continued) Contributory Subareas Northern Part of State Park Campground (Flows North) E-4, E-5 E-3 thru E-5 E-2 thru E-5 E-l thru E-6 Sut Southern Part of State Park Campground (Flows South) E-6 Location & Description of Improvements Southbound Carlsbad Blvd. Campspace 45 to Campspace 57 650' of 36" Southbound Carlsbad Blvd. Campspace 57 to Campspace 70 720' of 42" Southbound Carlsbad Blvd. Campspace 70 to 1,100 feet North of Encinas Creek Bridge 600' of 42" Southbound Carlsbad Blvd. 1,100 feet North of Encinas Creek Bridge to 400 feet North of Bridge 700 ' of 42" >total Southbound Carlsbad Blvd. Campspace 12 to the Campfire Center 1,000' of 18" Total Acres Served 17.6 19.3 21.9 22.8 3.5 Approximate Flow Line Depth (feet) 14 19 13 5 Costs (Thousands of Dollars) a 62 97 72 74 349 5 55 -49- TABLE 5-1 SUMMARY OF COST FOR MASTER DRAINAGE SYSTEM (continued) Contributory Subareas Southern Part of State Park Campground (Flows South) E-6, E-7 E-6 thru E-8 E-6 thru E-9 E-6 thru E-10 E-6 thru E-ll Sut Location & Description of Improvements Southbound Carlsbad Blvd. Campfire center to Campspace 205 950' of 27" Southbound Carlsbad Blvd. Campspace 205 to Campspace 183 1,150' of 54" Southbound Carlsbad Blvd. Campspace 183 to Campspace 168 750' of 54" Southbound Carlsbad Blvd. Campspace 168 to Southern end of Campground maintenance yard 900' of 72" Southbound Carlsbad Blvd. Southern end of Campground maintenance yard to Batiqui- tos Lagoon Bridge 1,200' of 72" Total Acres Served 7.8 45.7 47.4 116.9 118.0 Approximate Flow Line Depth (feet) 8 15 19 16 9 Costs (Thousands of Dollars) a 62 207 135 216 240 total 915 TOTAL 2,537 •*• Costs include engineering -50- The new drain will vary in size from 42" to 48". The approximate length of the needed improvements is 4,300' and the estimated cost is $495,000. Table 5-1 summarizes the needed improvements. Area D - Palomar Airport Road to Encinas Creek The drainage basins in this area are defined by the roads. Since the roads in this area may be changed as the area is developed as a state park, future drainage improvements should be integrated with the state park improvements. The future drain will have to begin near the Palomar Airport Road - Carlsbad Boulevard intersection. The drain will then continue south to the Encinas Creek Bridge. The new drain will vary in size from 18" to 27". The approximate length of the needed improvements is 3,240' and the estimated cost is $206,000. Table 5-1 summarizes the needed improvements. Area E - State -Park Campground There are two future drains which are needed to serve this area. Both drains begin between the trailer park and the developed Ponto Area. One of the drains flows north to the Encinas Creek Bridge and the other flows south to Batiquitos Lagoon. The northern drain varies in size from 18" to 42". The approximate length of the needed improvements is 3,470' and the estimated cost is $349,000. The southern drain varies in size from 18" to 72". The approximate length of the needed improvements is 5,950' and the estimated cost is $915,000. Table 5-1 summarizes the needed improvements for both drains. -51- LUor ou_ z:O => z: <a: o LU X "X.\- cr o CL LUf- h- LL O o: LUo:< Q o <£. «y. -• oCt O ^- 2 LU LUh-<h- (A) CO UJ o cro o:oh-co cc UJh- (O CD 10 Z i a: « UJ UJuj a: O - UJ zoen_j cn LU a: a:o: LU IE OZ CD Z oc. UJ CD UJ Zo 10 o „. o 0 - tO to 1 *3" >!f^^ CM ^_ o boooi J c CD U. O bom J 05 U. 0 bm K) | ^ <J LUo: LU LU LT O CO Z! ^ A~2L i LU 1 _ O ^ J J CJ r" h" _J =»QU.O ^T *— r O ££ i1—troa. <c o: ^o <Q. CO UJ h- -J o ^LIL. ^oro ^>o:o CO o:UJ Hco MATCH LINE SEE LEUCADIA STATE BEACH fi SI V'T ^'•••.pwm'•••••k --fa lfS'~• ' t % :tl 1 * f:> *3 ••* JF > CO U O< « «# ,\ , J»»l~ J» § I ;" ' 1"^r > " ' W — -mg f i ~•^; til l,rf :. *^ , .-. *.,-. /</ ,-.^?,i;,A'..'.?*i*a*^ "?•(. mr«-,,, '.M'T> -#' / v l' V,''/. ro i lO UJ CL Z) CD U_ tM LUN LU uu too 7Z b O S P< ^J I Z Oo a: O LL. I SOUTHERN PART OFTE PARK CAMPGROUND AREAO >> h- oro o:o (0 o:LJh-co tr UJ UJLJ o: 2 Z3 5 55z u. UJ 2 O APRIL 17, 1984 TO: CITY MANAGER FROM: Ray Koons REPORT ON BEACH EROSION AND SUGGESTIONS FOR REPAIR - On ocean-facing cliffs inside Carlsbad City Limits I had originally planned to secure maps and pinpoint areas of need. However, after spending about 10 days in the field going from north to south within the city limits, it became obvious that nearly all cliffs needed protection. In fact, if some areas that have eroded to within 10 feet of the edge of Carlsbad Boulevard (or old Hwy. 101) are not corrected by the time of next winter's storms, there could be closures and very expensive repairs. Now that I have put down what you have known for some time, I would like to offer my suggestions for the protection of the above. My experience in the past has been that rip rap has been the least costly and most effective in the control of water erosion. In your area, soil still remains at the base of some cliffs; at the base of others, it is down to bedrock. In the case where soil is evident, I suggest a toe trench of 10 feet - .... or an excavation 10-foot wide and down to bedrock or "0", whichever comes first, , and rip rap to height of 15 feet with a face slope of 1 1/2'-1' or preferably 2'-1' where it is permitted, consisting of 5-ton material with fractured face and not rounded as in some of the cases of existing rip rap jobs I saw in south Oceanside, which in some cases are failing due partly to that and material much too small...all, of course, with a sheet filter on the soil behind the rip rap. In the areas where there is no soil at the base, it is already down to bedrock; again, the same specs as above except at the base since there is no toe trench, it is suggested a 10-foot wide apron of 5-ton material be placed from the toe of the rip rap to seaward. It is of the utmost importance that the material be placed so that the pieces interlock and not just be dumped in such a manner as to make a pile. In walking areas on top of bluffs, I noted too much erosion from water run-off; much of this can be averted by backfilling all asphalt concrete dikes and concrete curbs to a height of a few inches above the top and out to a distance that is practical, with a minimum of 1.5% crossfall to the face of curb and thereby diverting that water back to a controlled area. Now back to the areas where erosion has occurred to within a few feet of the edge of roadway. One fix would be to place 4" of reinforced gunite with deadmen. Of course, if any of these ideas were to be accepted, there would have to be plans and specs in much nore detail. APRIL 17, 1984 . - , ' REPORT OH BEACH EROSION PAGE 2 Also, there are areas where spillways and "V" ditches would greatly aid in control of erosin. These can be constructed of asphalt concrete, gunite, shotcrete or concrete. There are many advantages of spillways and "V" ditches over pipe, such as ease of maintenance, capacity, etc. Another very large contributor to erosion is the very large population of squirrels and gophers. Their burrows and tunnels sometimes start at the top of the cliffs and many times daylight on the slope, which in turn becomes a water course in rain and causes unneccesary erosion. In the area just north of the State R.V. park where the roadbed is only a few feet above sea level, one solution would be to raise the level of the roadbed a minimum of 15 feet - from its lowest point and carry that elevation both north and south until it daylights into existing roadway, then rip rap the seaward side. There are other fixes, less permanent, that can be discussed at another time. In the southbound lanes of old Hwy. 101 on the downgrade approaching Ponto Beach, a good section of the roadbed has started to slip into the sea and would need some immediate attention. That means some work on the toe of the cliff as well as the roadbed. Again, this needs more explanation than this brief notation. ^l**(V C I understand there is a possibility of widening Carlsbad Boulevard from Tamarack south to the power plant. I have suggested to you that you might think about moving the roadbed 30 feet to the east and raising the southbound lanes only a minimum of 10 feet. In other words, a split-level, then rip rap the seaward side. If in the future you or anyone else wishes to discuss this report in more detail, I will make myself available. Also, I have some ideas about replacing sand on the beaches. RAY KDCNS RKtdls eA llrOCrS ' \ il ITt M-, (joa>yt<*x a*3t VceA>^ £#K?, %'<ir. PREDICTED EXTREME HIGH TIDES FOR CALIFORNIA 1983-2000 Bernard D. Zetler and Reinhard E. Flick Scripps Institution of Oceanography ABSTRACT At the time that a combination of high tides and severe storm induced waves devastated California's coast in the winter of 1982- 1983* dire predictions of much higher tides in the early 1990's appeared in the press. Standard harmonic tide predictions have been prepared for San Diego. Los Angeles. San Francisco and Humboldt Bay extending until the year 2000. These show that the range between annual extremes at any station is only 0. 4 foot V (0. 12 m) with the highest tides predicted during the period 1986- 1990, and comparable lower maxima about 9 years later. We suggest that the peak enhancement in 1987 of the diurnal lunar tidal constituents due to the 18.61 year cycle of lunar nodes primarily accounts for this variation in magnitude and phase. Although the predicted tides may be exceeded somewhat due to a gradual global rise in sea level (0.5 foot, or 0.15 m over the past century) and If severe storms occur at times of extreme high tides* it is reassuring that future astronomical components of extreme tides will exceed those of 1982-1983 by at most several tenths of a foot (0. 06-0. 09 m). c CO UJo UJ cch- X UJ o UJ H- O Q UJ CC Q_ ^Qi ! ooo CO en' en<J> 00Cn Cn f^-Cn Cn tO en Cn mo>en <ren<n o 4* 01>•ft 4> (Q i—i 01 iff «-• 01•o iff •r« 01 4* *•« J3 ; ^: ; I ; • - • [ : - \ ': -. _ ; r : ; • — = • - :I I ; - rO<n<T> CMen 2 enen oenen enCOen COCOen r»-00en O3COen mooen ^ 01601t- 4> M Of -o Olt*+* .u •r* ^M^901t-o. <*.o Iff 4» O fl0_ • 1^ 01 t-3 Ol •>4 U. c •M •o 01 4* « *•* l» 4» Iff * e3 4* <D•o 4* (.••.cu Ol> •^4 4> U &inw 01(. *r COen ro COen o en i i o CO* 1 1 o ^-. 1 j O CO . i h — n o•r- ^ l 1 c> to L ->-— i o r- h— r j <D UJ i J q CO _^— i n q r«- - 1 =1 q u>* EXTREME SEA LEVELS ON THE COAST OF CALIFORNIA Relnhard E. Flick Center for Coastal Studies Scripps Institution of Oceanography 1. INTRODUCTION The coincidence of high sea level and large waves caused millions of dollars of damage to public and private property on the California coast during the winter of 1982-83. The unusually high sea levels were due to a combination of higher than normal mixed layer temperature associated with a strong, 2-year El Nino, high astronomical spring tides, storm surge due to low atmospheric pressure and persistent onshore winds and the cumulative effect of steady, "global" rise 1n relative sea level . Studies are underway to identify and quantify episodes of high sea level anomaly, defined as a given excess over the predicted astronomical tides, and where possible to relate these to descriptions or summaries of the wind, storm events and local sea temperature to enable assessment of coastal flooding risks in engineering terms. The purpose jjf this paper is to present the methods and prelim- { *ry results of the sea level portion of these Wvestlgations. While no reliable predictions are possible for times (at scales of months or years) and heights of future sea level components other than the tides, detailed examination of the wide variety of historical events can yield valuable in- formation on the range of possibilities and esti- mates of the statistical recurrence intervals. 2. ASTRONOMICAL TIDES The predictions of astronomical tides prepared and published routinely by the National Ocean Ser- vice, NOAA, are a much used and valuable indicator of future episodes of possible coastal flooding. A study of the extreme high tides using NOAA predic- tions for California for the years 1983-2000 has been completed by Zetler and Flick (1984) and this shows some interesting features whose relevance to coastal flooding has not been widely recognized. First, tidal constituents beat to. produce higher "spring" tides in summer and in winter, com- pletely masking the seasonal mean sea level compo- nent, which is low in spring and high in fall due to seasonal heating and cooling and variations in geostrophically balanced coastal currents (Reid and Mantyla, 1976). Second, a distinct 4.4-year beat- ing due to the Interaction of the 8.8-year cycle of lunar perigee and the twice-yearly solar equinoxes (Cartwright, 1974), raises spring tides about 0.5 ft every 4.4 years compared with times in between. Finally, the progression of lunar nodes introduces n 18.6-year cycle which will Increase the spring ides by about 0.2 ft in the period 1986-1990 com- red with 9 years later. 3. MEAN SEA LEVEL Recent studies of global mean sea level rise indicate typical values of 0.5 ft per century (Hicks et al, 1983; Aubrey and Emery, 1983; Barnett, 19831 Figure 1 shows yearly mean sea levels observed at La Jolla-Scrlpps Institution Pier. The trend from 1925-1983 Is Q.64 ft per century with significant positive departures from the trend around 1930, 1941, 1958, 1967 and 1983, all cited as El N1foyears (Namlas, 1976). More detail can be seen in Figure 2 showing the seasonal cycle of monthly mean sea level (dots and heavy line) and the rms departure (vertical bars) for the 1960-78 tidal epoch. The lighter lines show the monthly averages for 1982 (broken) and 1983 (solid) and illustrate the severe, 3 or 4 standard deviation departure from normal during these years. The trend between the middle of the epoch and 1983 accounts for only about 0.1 ft of the anomaly, or less than one-half standard devia-tion. L» M.U-M NCI ItMU KM Kt LtVll nn iir« mo Fig. 1. Steady increase in yearly mean sea level at La Jolla is comparable to "global" rate of 0.5 ft/century. Departures from trend (shaded) coincide with El Nino years. JOU.A-SIO Pl« MMTW.f HEM Xt lEVCl „ S.O i Vi pa Fig. 2. Heavy line shows monthly means for 1960-78 tidal epoch. Bars are rms variation for each monthly average. Light lines show monthly values for 1982 (broken) and 1983 (solid). Arrow indicates magnitude of trend from middle of epoch to 1983. c EXTREME SEA LEVELS AND ANOMALIES Monthly and seasonal extreme sea levels have ibeen examined for a number of coastal stations In- cluding San Diego, Newport Beach and San Francisco. 'Figure 3 shows the maximum sea level observed dur- jlng the November to April stem season for eachyear .since 1897-98. The maximum value recorded, 8.8 ft above MLLW, was reached 1n January 1983. This .represented a 1.7 ft excess over the 7.1 ft predic- ted high tide, as shown 1n the anomaly record, Figure 4. While this anomaly was large, It was not 'as high as the 1.9 ft excess observed during Decem- ber 1940, when the predicted tide was only 6.1 ft. In January 1983, about 0.3 ft of the excess water level could be attributed to the gradual sea level rise since 1940. On the order of 1 ft could be .related to El NITTo effects, with the remainder due to meteorological forcing. IM riMcncg MHMI iciswu im-m.1 «« um «•« *•' I" C t.l The anomalies shown In Figure 4 cm be reduced to • emulative distribution or a probability of exceedence of a given anomaly value. With assump- tions about the for* of this statistic. It can be plotted In terns of return period. This approach shows that anomalies as large as 1.2 ft recur every 4 yean on the average. It 1s Important to realize that this anomaly distribution Is not the same as the largest seasonal difference between observed and predicted tide. This Is merely the anomaly at the time of maximum monthly sea level. Work 1n progress will examine the distribution of hourly sea level observations and anomalies to determine the underlying statistics. Other work 1n progress will more carefully examine the relationship of local forcing of sea level by wind, atmospheric pressure and ocean temp- erature on time scales of 2 to 30 days. This Is an Interesting scientific problem deemed directly relevant to local agencies charged with the protec- tion of life and property. Weather and surf fore- casts together with tide predictions are the only means available to local jurisdictions to antici- pate coastal flooding disasters. Weather forecasts for 3 to 5 days In advance are vastly more reliable than longer-term forecasts, so that If large sea level surges are well correlated with local weather systems on this scale, they are In this sense more "predictable" as well. Fig. 3. Seasonal maximum sea level height at San Francisco relative to MLLW of 1960-78 epoch. Note the rising trend since at least 1930. Four events (labeled) standout. SM riMCIKO WIHMI SfMtttU IIM-1MI 1C* IIVU HCWt F1g. 4. Anomalous sea level height over the pre- dicted tide at times of seasonal maximum sea level. Seven events (labeled) exceed 1.6 ft. S. REFERENCES Aubrey. D.G. and K.O. Emery, 1983, "E1genanalys1s • of recent United States sea levels," Cont. Shelf Res.. 2(1), p. 21-33. Barnett, T.P., 1983, "Recent changes 1n sea level and their probable causes," Climatic Change. 5, p. 15-38. Cartwrlght, D.E., 1974, "Years of peak astronomical tides," Nature. 248(5450), p. 656-657. Hicks, S.D., H.A. Debaugh, Jr., and I.E. Hlckman, Jr., 1983, "Set level variations for the United States 1855-1980." U.S. Oept. Commerce. Namlas, J.. 1976, "Some statistical and synoptic characteristics associated with El Nino," Jour. Phys. Oceanog.. v. 6, p. 130-138. Reid. J.L. and A.W. Mantyla, 1976. "The effect of the geostrophic flow upon coastal sea eleva- tions In the northern North Pacific Ocean," Jour. Geophys. Res., v. 81, n. 18, p. 3100-10. Zetler, B.C. and R.E. Flick, submitted. "Predicted extreme high tides for California. 1983-2000," Jour. Waterway. Port. Coastal and Ocean Enq. D1v.. Amer. Soc. Civil Eng. ) Co&rtal O PERFORMANCE DOCUMENTATION OF THE LONGARD TUBE AT DEL MAR, CALIFORNIA 1980-1983 Reinhard E. Flick and B. Walton Waldorf Center for Coastal Studies Scripps Institution of Oceanography La Jolla, California 92093 ABSTRACT The Longard Tube experimental revetment installed in Del Mar California in December 1980 has been monitored and its performance documented until it subsided and became ineffective during the severe winter storms of December 1982 to March 1983. The data suggest that the tube had no measurable effect on the sand level at Del Mar beach. The beach profile monitoring program conducted by Scripps in Del Mar since 1974 served as important background information for the design and interpretation of the monitoring program measurements. The tube experienced relatively minor storm wave interaction during winter 1980-81. This was followed by heavy beach accretion on the entire reach in spring 1981 and an unusually mild winter of 1981-82. By Julg 1982 the tube was totally buried behind a berm extending 35 m seaward. The severe winter storm waves of 1982-83 coupled with high sea level due to high spring astronomical tides/ sustained onshore westerly winds and low atmospheric pressure* eroded the sand level on Del Mar beach to the lowest level in at least 10 years. The Longard Tube settled differentially by up to 2 m and was continually overtopped at high tide rendering it ineffective by Late January 1983. It was removed in March 1983. The principal conclusion of the study is that the Longard Tube configured as it was in the Del Mar test is not a substantial enough barrier to effectively prevent beach sand erosion during severe storm events on the Southern California coast. 27 £861' 03AON3U 3801 QUV9N01 <to CJ co ^ lO ii i CC CM O 1861'NVr Q311V1SNI 38 nj. QdVONOI CJ 00a> aoo Oooo> aienc QJ o cn in •M <O E-0•f- I. •«-> <0env> c.3 O SJ5 O'r- f 4->(A (O QJ^s- ato $-««- CSJ JZo a>i0 ena> c en oc T-0) +tr- tOo •M O 3 i. O)o.in II"o en> v- C OJ10 a> cn 3en Oin inCM oo 'V,.,,,- (HOV38 |0 ui/£uj) mCM 3A08V 3WniOA ONVS g"g 5-S-SIH3 S-3O OQ S. •»a." •B B'3 S " sr si g^cS-^S-B, :» i I" 35*-si^r: -a A 3 ^ *"** CA 7+r ~ ft fa .«• ? J= » ^ B **• 3 *•- «5|,1. f 0 g » 8 | ^ »| I? ~ BT ». £ I- S 8- 3. =» s O E" . . rJi •». F^ _ _•» A. ^ CD CDO O ZJu> Q</> <D c A hpuse on the bea'ch? What beach? It is a sad irony that when people construct buildings on coastal beaches, they often end up destroying the beaches to save the buildings. In re- cent years, a group of concerned geol- ogists, spearheaded by Orrin H. Pilkey Jr. of Duke University, has been warn- ing the American public about what they feel has been the folly in the mismanagement of eroding beaches. They argue that all engineering solu- tions (erection of jetties, groins, sea walls, and the like—called stabilize, tion) have caused the irreversible loss of beaches, and they're .trying to make the public aware of the problem and thus permit major changes in beach, erosion policies. Geologists say that SO to 90 percent of America's beaches are eroding. This they attribute to a worldwide rise in sea level. Beach erosion be- comes a problem, however, only when people erect buildings on beaches. When sea walls and bulkheads are built to protect the buildings, they de- stroy the beaches. Sea walls cause the shoreface to become steeper and wave energy to increase. Eventually waves erode the beach up to the wall. The specialists view engineers as adversaries in the struggle against beach erosion because engineers be- lieve that stabilization can protect buildings and still maintain beaches, whereas geologists are skeptical. "Any- thing and everything done to stabilize a beach is a long-range (and perhaps short-range) environmental mistake," Pilkey claims. The geologist's case against coastal stabilization is a strong one, and the evidence is ample. Vanished and dam- aged beaches caused by man-made structures are found all along the American coast. Pilkey calls the phe- nomenon "New Jerseyization," be- cause of the devastated beaches of Sea Bright, Long Branch, Cape May, Mon- mouth Beach, and other New Jersey communities. A New Jerseyized beach is a beach that has disappeared. All that stands in front of buildings along the shore are sea walls and the rub- ble of older sea walls. In Miami Beach, where sea walls were erected to protect the hotels along the coast, the beach eroded completely. In the '60s and 70s there was virtually no beach in Miami Btach. A 15-mile stretch was replen- ished at a cost of $64 million, and it wii! have to be replenished every dec- ade or so at ever greater cost. What should be done? Nothing, ac- cord.ng to Pilkey and his colleagues. They ^el that building on beaches should be prohibited and restricted. Pilke writes that "the obvious solu- tion t' New Jerseyization is simple: Stop all island and coastal stabiliza- tion projects. Let the ocean and shore reach an equilibrium." It is > rucial, geologists believe, for Americans to realize the seriousness of the beach-erosion problem. As Pil- key put: it: "We have two mutually exclusiv choices: beaches or build- ings. We can't have boih. A choice must be ir.ade." —Michael Neubarth Astro Surf By Guernsey Le PeUey C OASTAL erosion is one of the natural func- tions going on in the world of geology. Nature seems to be none the worse for it, but ft both- ers people. Beach types go bonkers over erosion even though it has been around longer than taxes. It is an obvious act of discrimination against folks who Uvfc by the seaside.' Thus far it has never oc- curred to Debate not to build houses too close to the water, eveatMugh the fact that tides and waves can- not brregulfltod was settled by King Canute back around £$1020. The latest coastal-consciousnessitem on the mar- ket is fake (JMkreed. This comprises strips of plastic grtflfct teijijf JjMriyide; stuck in long rows off the coast and (Mid ijSrrfice by sandbags. Not a very remark- able idif, btt^-vhen one thinks of the length of inhab- ited coastline it boggles the mind. So far, no one is absolutely sum whether the fake sea grass will build up thai sand and prevent erosion. Officials always approach something as absurdly expensive as this with an open mind. It is sure to mean money in the pockets of somebody, even though hr comes out of the pocket of someone else. Presumably, plastics manufacturers, who gave us AstroTurf, would be in favor of it As always, in the normal course of politics, there is a diversity of opinion. Although some have a fair amount of confidence in how the seaweed barrier will affect the shoreline, no one is sure how it will affect the turtles. Turtles, as a look at one plainly tells, are border- line cases to begin with. They are perhaps the one species less keen wftted than seaside dwellers, and might not know the difference between real grass and plastic grass. At times of the year they can be as stubbornly beach-committed as their human cpunter- parts. A frequent diet of plastic grass might eliminate the turtle population once and for all. • In some areas, turtles have been known to eat plastic already. Not grass. .Presumably just plastic bananas, apples, and whatnot, used for decoration and finally cast into the sea. The outcome seems inevitable. Once all this plas- tic grass is in place, weighted down with sandbags, them will be nothiafto do but put in plastic turtles. Either that, or quit building houses on the beach. PULSE OF THE MOON Nantucket Island has tides of about a foot, while the Bay of Fundy, just a few hundred miles away, has 53-foot tides. Why? The rise and fall of tides is simple enough in theory. Imagine the Earth completely covered by oceans. At a point directly beneath the moon, its gravity raises a bulge and swells it by pulling in surrounding water. On the exact opposite side of the planet, the moon's pull is weakest. But since the Earth and moon circle each other, the water on the far side also bulges, just as hair streams backward from a cou- ple swinging at a square dance. Both the bulges stay in line with the moon as Earth turns on its axis. In fact, it isn't so much that the tides move but that we move into them. The sun causes tides, too. When Earth, moon and sun are in line, as at new and full moons, the effects add up, producing spring, or maximum, tides (the name has nothing to do with the season). But when the moon is in its first or third quarter, tides are sub- dued; these are neap tides. Solar tides are only half as high as lunar tides, but not because the sun is 400 times farther away. What counts in tides is the difference in pull on op- posite sides of the Earth. Given the sun's distance, its effect on both ends of Earth's 8,000-mile diameter is about the same. The moon's pull, how- ever, weakens significantly from one side to the other. Unfortunately for those who predict high and low water, the real world is much more complicated than the the- oretical one. The sun and moon ap- pear over the Earth at ever-changing distances and latitudes. Friction be- tween seawater and sea bottom keeps the bulges from moving freely. Shapes of continental shorelines and shelves add to the confusion. The result: Some places have high tides once a day, some twice; some are measured in inches, some in feet and some in tens of feet. Supertides occur when a tidal bulge enters the mouth of a long, shallow, funnel-shaped inlet, causing a wave that sloshes up to the end and back. If the inlet is the right shape, the wave will return to the entrance just in time for the next high tide. The wave thus gets a push on every cycle and is inten- sified, creating the highs and lows that make the Bay of Fundy, for one, a prime location for tapping tidal energy. -Michael Lemonick 14 Science Digcsi—September 1983 MARCH 1984 VOLUME 2, Number 1 US Army Corps of Engineers Los Angeles District San Diego Coastline Quarterly is financed with federal funds from the U.S. ASSOCIATION OF Army Corps of Engineers, Los Angeles District, and local funds GOVERNMENTS from SANDAG member jurisdictions. NEWS FROM COASTLINE COMMUNITIES Del Mar On November 14 the City Council met in special workshop session to discuss coastline and beach use issues. The Council voted unanimously to hire a consultant who would prepare an Environmental Impact Report on several proposals for beach shoreline protection from winter storms. At the heart of the issue is the need to develop a plan which addresses the complex problem of beach erosion, protecting private property on the coastline, and assuring continued public access. The State Coastal Commission has proposed September 1, 1984 as the date by which Del Mar must have adopted a plan which includes agreement with private property owners along the 1.2 mile beach. The consultant's plan calls for a 15-foot wide sand walkway, protected by a timber or concrete seawall, and kept open to the public. Other alternatives being considered include seawalls on private property, a combination wall built on private and public beach, and rock beach barricades that could be covered with sand in summer months. Oceanside PROPOSITION L UPDATE: As a part of the November 8 General Election, resi- dents of the City of Oceanside defeated Proposition L. The proposition would have raised $14.9 million through the sale of bonds for the restoration and preservation of city beaches and some other shoreline related projects. There was considerable debate on the proposition which was covered closely by the local press. Even the City Council was divided on the issue. Proponents argued that the construction of adjustable groins would help replenish beaches and eliminate future winter wave erosion. The restored beaches, it was argued, would be key ele- ments in implementing the City's downtown redevelopment plan. Opponents claimed that the groins were no "quick fix" and that a sand replenishment program at additional cost would be necessary. The claim that the groins had been successful in other Pacific coast communities was also challenged. The final vote on Proposition L was 36% for and 64% against, a 2-1 rejection. Carlsbad In May 1983, a 1100' Longard Tube was installed in Carlsbad, the largest on the West Coast. The Tube (aka Beach Bologna) is made of woven polyethylene plastic and coated with epoxy and sand. It is buried in the beach and designed to reduce winter wave caused beach erosion by dissipating wave energy. Bob Wojcik of the City Engineering Department reports that so far the results are positive, based on the City's surveys of the project. The Carlsbad staff is measuring beach profiles on a quarterly basis along the 1100 feet, and Scripps Institution of Oceanography is doing sand depth measurements at the north and south ends for comparison. The tube is in place between Oak and Elm Avenues in Carlsbad and is on predomi- nantly private property. (Coverphoto) NEW STAFF JOIN COASTAL STUD\f The Coast of California Storm and Tidal Waves study has been strengthened by the addition of two staff members. Their expertise in specific areas should greatly aid the work being done. Tom Dolan started work on October 1st as a new project leader. He has an MS in Environmental Engineering and another in Oceanography from the University of Delaware. Mr. Dolan will be responsible for overseeing the technical aspects of the study and also for directing the work of the Scripps Institution and other tech- nical contractors. Tom Richardson has joined the staff as a technical advisor in the area of coastal structures. He has been assigned from the Coastal Engineering Research Center in Vicksburg, Mississippi where he is the chief of the Coastal Structures and Eval- uation Branch. SAND BYPASS PROJECT PROCEEDS In 1942 the Second World War put requirements on the Marine Corps which meant rapid expansion of their training facilities. In that year the Marines dredged and constructed a harbor at the mouth of the San Luis Rey River to accommodate amphibious operations. Since then a significant quantity of sand has been diverted into the harbor depriv- ing beaches to the south of a regular flow of sand and necessitating frequent dredging of the harbor. A solution to this problem has been undertaken by the U.S. Army Corps of Engineers and is hoped to be completed and operating by December 1984. The plan involves pumping sand around the harbor opening through about one mile of pipeline and discharging it along city beaches as far south as Wisconsin Avenue. In order to do this, pumps will be installed in the harbor which will "fluidize" the sand as it is deposited and send it under pressure to the beachf The Corps estimated cost for the "base plan" project is $4.5 million. $3.2 million is currently available for the construction with an additional $1.3 million to be programmed in FY 1985. Historical Shoreline Change Maps completed for San Diegoand Orange Counties. COAST OF CALIFORNIA STORM AND TIDAL WAVES STUDY UPDATE Coastline Quarterly recently interviewed project manager Dan Muslin of the U.S. Army Corps of Engineers. Mr. Muslin provided an update on some important aspects of the Coast of California Storm and Tidal Waves Study as follows: * Wave gauges have been placed on the ocean floor off Imperial Beach, Del Mar, Oceanside and San Clemente. These join the gauge in place off Mission Beach since August 1978. The devices measure wave action intensity and variation, and report the data electronically to the Shore Processes Lab at the Scripps Institution of Ocean- ography. The write-up of the first set of findings is due in March 1984. Success of this phase of the project is encour- aging consideration of installation of a sixth gauge in the Camp Pendleton area. * Beach profile work began in early October. A beach profile is a cross-sectional description of the beach; how deep, the slope, etc. The study intends to do two sets; the first in November 1983, and the second in February 1984. In this way the changes in beach profiles caused by winter storms can be measured. At the same time sand samples are being taken on the beaches. The grain size and composition of the sand gives a good idea of its place of origin along the coast and how far it has travelled. * The National Ocean Service has delivered a set of Historic Shoreline Maps for use in the study. The maps show the shoreline for seven points in time from 1852 to 1982 and how it has changed due to natural and human activity. The above map illustrates three different years for a portion of San Diego Bay. By comparing the maps with historic meteorological information it is possible to deter- mine the effects of winter storms on the configuration of the beach of a long period of time. * An $80,000 contract has been let to the United States Geologic Survey to install and monitor stream gauges. The gauges record flows of water in coastal streams, and thus help measure the movement of sediment to the coastline and beaches. Gauges will be installed soon in San Juan and San Mateo Creeks and the Santa Margarita, San Luis Rey and San Diego Rivers. Wave Gauge being installed in Imperial Beach TIJUANA SEWAGE AFFECTS LOCAL BEACHES BEACHES REOPEN AFTER SEWAGE QUARANTINE — LONG TERM SOLUTION STILL NEEDED. Northern beaches in the City of Imperial Beach were re- opened to public use on February 9. They had been closed since December 30, 1983 by raw sewage leaking from breaks in a main in Tijuana. Nearly 3 million gallons per day were flowing north across the border and into the Tijuana River, closing Border Field State Park and the Tijuana River National Wildlife Refuge as well as the beaches. Relief has been brought through an emergency solution implemented by the U.S. International Boundary and Water Commission. A 13-acre holding pond has been constructed to contain the largest leak at Smugglers Gulch. At night, when flows north of the border are reduced, the sewage is pumped into the San Diego municipal system and treated. Sewage is still flowing across the border at a second location, Stuarts Drain, at a rate of about 500,000 gallons per day. While hardly desirable, this flow will evidently enable the beaches to stay open. Officials from both nations are scheduled to meet to try and resolve a long-term solution. Repair of the Mexican system is the first step; but at best, untreated sewage from Tijuana (a city of nearly 900,000 persons) flows into the ocean only 3.2 miles south of the border. Possible future solutions include treating the wastewater in the U.S. under contract, or con- structing a treatment plant and/or a new deepwater outfall in Mexico. Least Tern RESTORATION ACTIONS IN LOS PENASQUITOS LAGOON UNDERWAY The California Coastal Conservancy is organizing a nonprofit public benefit corporation to advise the Conservancy on resto- ration actions in Los Penasquitos Lagoon. The corporation's purposes include the preservation of land for scientific, historic, educational, ecological, recreational, agricultural, scenic or open space opportunities, and the restoration of the Lagoon. The corporation's initial directors will be Don Rose of San Diego Gas and Electric Company, Bill Fait of the California Department of Parks and Recreation, Stuart Shaffer of the San Diego Association of Governments, Joan Jackson of Carlsbad, Steve Tate of the Baldwin Company, Del Mar, and Dwight Worden of Solana Beach. Work to be carried out at Los Penasquitos will include field investigations to determine the depth, areal extent, and material composition of the beach sediments at the Lagoon mouth. These data will be used to analyze the hydraulic characteristics of tidal openings to the ocean and the likeli- hood they will remain open throughout the year. To obtain the necessary data on the Lagoon mouth, several holes will be drilled in the beach. These holes will be drilled down to the top of, but not through, the cobble sill that underlies the beach sands. The holes will be drilled in a pattern that will allow an estimate of the depth to and the areal size of the cobble sill. Samples of the beach sediments overlying the cobble sill will be collected and analyzed to estimate flushing velocities needed at the Lagoon mouth. A study will also be made of the potential of providing a self- flushing channel between the ocean and Lagoon. Alternative methods of constructing such a channel will be investigated and the amounts of material that would be removed from the mouth for various sized channels will be estimated. In addition to a self-flushing channel, some structural methods to help keep the Lagoon mouth open will also be investigated. These structure types will involve periodic dredging, fluidization of channel mouth sediments, jetties, and tidal gates. The volume of water that flows in or out of a lagoon during a tide cycle is the lagoon's "tidal prism." To a large extent, the tidal prism determines whether or not the lagoon can naturally maintain an opening to the ocean. An analysis will be made of the minimum tidal prism required to maintain an opening at Los Penasquitos. The analysis will include, of course, an estimate of the amount of material that must be removed from the Lagoon to maintain the prism. The National Weather Service Dynamic Wave Operational Model will be used to calculate varying flow depths and velocities in the Lagoon channels during a tide cycle as well as varying water depths and areas of inundation in mud flats adjacent to or hydraulically connected to the channels. The model will also be used to estimate the current and historical tidal prism and alternative Lagoon modifications that could increase Lagoon habitat enhancement. Existing Lagoon habitats will be confirmed as well as the effects of alternative Lagoon modifications on them. All data will then be synthesized into alternatives, including costs and estimates of effectiveness. The alternatives will then be presented to the Foundation Board for review and action. STUDY TO IDENTIFY EFFECTS OFCRESHWATER RELEASE ON COASTAL WETLANDS The San Diego State University Foundation and the San Diego Association of Governments are preparing a manage- ment plan for implementation of local agencies to minimize the negative impacts — and maximize the beneficial impacts, on coastal wetlands of freshwater released into Southern Cali- fornia streams. The study areas for the project will be the Tijuana River Estuary (one of the State Water Resources Control Board's "priority water bodies") and the lower San Diego River. The study is scheduled to be completed in the late summer of 1984. Joy Zedler, Professor of Biology at San Diego State University, is the principal investigator for the project. The study's major products will include (a) a management plan containing implementable recommendations for the release of freshwater into the Tijuana and San Diego Rivers; (b) an institutional and financial plan to implement the management recommendations; (c) estimates of the impacts of varying streamflows on water salinity in coastal wetlands; (d) an evaluation and forecast of ecological changes in the coastal wetlands resulting from various freshwater regimens; and (e) wetlands restoration plans based on increased fresh- water input. Background When imported water is released into Southern California "reams, it eventually makes its way into the region's normally aline coastal wetlands. There the excess freshwater can have either negative impacts on the native ecosystems (if timing or quantities of freshwater input are incompatible with the plant and animal species) or beneficial effects (if discharges are planned to occur when excess freshwater is not damaging and where freshwater can assist in restoring degraded wetland habitats). To date, most freshwater releases have occurred with regard for consequences downstream, and major changes in coastal salt marshes have been documented. The need to develop water management practices that are compatible with coastal water bodies follows from these facts: 1. Watershed management practices ultimately impact coastal wetlands downstream. 2. Coastal wetlands are environmentally sensitive habitats that are protected by the Coastal Act. 3. Coastal wetland species are highly sensitive to changes in the salinity of their environment (both water and sediments). Changes in the normal timing and volumes of freshwater input can affect wetland species (Zedler 1982 and in press). 4. Release of freshwater that has been imported to the region can significantly modify the normal freshwater/seawater regime to which coastal wetland organisms are adapted. Several watershed management plans call for increased release of freshwater to Southern California rivers, either as a consequence of wastewater recycling projects or as deliberate plans to create "live streams" for esthetic or recreational appeal. Under natural conditions, Southern California, coastal water bodies are dominated by tidal sea water that circulates through narrow connections with the ocean. The lagoon and channel waters are usually at a salinity equilibrium (3i/£% salt) with the ocean because of tidal mixing. In the shallow areas along the periphery of the lagoon waters, sediments become much more saline than sea water (sometimes exceed- ing 4-6% salt) due to evaporation at low tide and the concen- trating effects of vegetation. The plant and animal species that normally inhabit the coastal wetlands are adapted to tolerate these saline condi- tions. Past destruction of large areas of saline habitats has reduced several species to endangered status, indicating the degree to which native plants and animals depend on natural habitats. The discharge of large volumes of freshwater year round would greatly modify the hydrology of coastal water bodies. If flow is sufficient to dominate the water body, as occurred with augmented flood flows in both the Tijuana River Estuary and the Lower San Diego River in 1980, the system will shift to a freshwater body, and the adjacent sediments will be leached of salts. While the ecological effects are not fully understood, it is clear that such hydrological modifications had negative impacts on coastal wetland species and that habitat for endangered birds was affected. Further research is needed to identify the many impacts of augmenting river flow, but it is not too soon to recognize the problems and to develop plans to mitigate damages. Tijuana Estuary (Facing south). T9SI ' VO ' -LU\TH3d UBS 'ST1 0021 3TJI3BJ AjUn? 1O NOIXVIDOSSvooaia MVS «V BEACH3UILD5RS OF AMERICA, INC. Coastal Protection Methods - A Study and Conclusions Introduction: "Coastal protective works of major order probably first came into existence when man was forced to protect the land which he lived on to avoid the waters digging away the ground under his feet". These are the words of Per Bruun, in his paper, • . 3 The History and Philosophy of Coastal Protection. There have been many types of erosion control methods tested and tried w'ith varying degrees of success. In reading through the many volumes of works describing technical data regarding i « protection systems ranging from groins to elaborate dredging operations, we have found that the Beachbuilder System has been substantiated by many of these studies. Beachbuilders is a system which attempts to harness the forces of nature to rebuild and restore our eroding shoreline. This paper is a correlation of information which supports our system. According to Dr. Bruun^, "The earliest reference to the art of accelerating the natural rate of accretion is the manuscript "Tractaet van Dijckagie" (Treatise on Dikebuilding), written by the Dutch dykemaster Andries Vierlingh, between 1576 and 1579". He discusses the construction of "cross-dams" on mud-flats using old ships with earth dumped on top of them so as to make artificial islands or flats which should hold back silt or sand suspended in the water. Vierlingh, however, was against this shipwreck method of closing dyke breaches because of the non-homegenity they created in the dyke structure. VierlinghTs advice included this main thought, "Water shall• not be compelled by any fortse or it will return that fortse K onto you". An overview of progressive erosion conditions in many areas substantiates this theory. One need only use the naked eye to witness massive slabs of concrete and "steel, tossed about and undermined by the forces of the sea. This force and power, however, when used properly, can be channeled into a constructive rather.than destructive condition. Erosion is either paused by nature or man-made. Any protection system that man designs has beforehand been tried and tested by nature, therefore, we can learn from nature through it*s successes if we will observe and imitate. This is a simple rule that man tends to ignore in his ever present attempts to over-complicate matters. Often times in our efforts to correct a situation, we have compounded the problem. As Dr. Bruun states^, "What destruction effect nature in-its abundance has demonstrated man unfortunately has imitated. Man-made erosion is a black spot on manTs association with shores. It is a deplorable fact that all coastal protection measures apart from artificial nourishment (may) have an adverse affect on adjoining shores". » •• ,• When we speak of erosion we refer to the loss of beach due to a disturbance of the natural equilibrium. Statements by W. Basconr, in his paper "Characteristics of Natural Beaches"« substantiate this fact: "The most important characteristic of a beach is its dynamic nature; beaches are restless, ever- shifting groups of particles which respond with great sensitivity to small changes in the natural forces that are quite imperceptible to man. A concept of this ceaseless change which reflects the wave charac- teristics is absolutely essential to the understanding of beach problems", p 163 " A beach is a deposit of material which is in transit either along shore or off-and-on shore". G.K. Gilbert (1390) D.W. Johnson (1919) p. 165 "Man, in building shoreline structures that obstruct or influence littoral sand flows almost invariably creates a dual problem; (1) sand will deposit wherever comparatively quiet water is created and (2) cutoff the supply of sand to beaches downstream from the structure which will retreat", pp. 173-175 The statement "sand will deposit wherever comparatively quiet water is created" is the basis for our natural means of shore protection. The formation of offshore bars is a natural procedure which ultimately protects the beach and maintains equilibrium. W. Bascora explains the phenomenon as follows: "Consider a beach with an even sloping bottom (barless beach profile) which is subject to light wave action; sand is moved slowly ashore by the mechanisms dis- :. cussed later under Forces. A storm arises and the waves become.much higher; more bottom is affected, because the waves feel bottom sooner and sand continues to move towards shore from comparatively deep water. When these waves break and become translatory, the water moves forward with the wave form; its natural return is a seaward-flowing bottom current which transports sand eroded from the beach face. This seaward moving sand meets the shoreward moving sand under the line of breakers (where the transformation from oscillatory to translatory waves takes place); at this point the opposing currents neutralize each.other and the sand deposits to form a bar. Once the'process starts'the effect is''"pro- gressive. The rising mound of sand (the bar) causes more waves to break since it is shallower; it also . corcentrates the breakers of slightly varying height (which formerly broke at their respective depths) in one place. Waves are thus filtered by the bar; only those less than some critical height pass across without breaking - when these reach some appropriate depth, they also break and an inner bar may be formed. When bar formation has progressed sufficiently, the bar projects well above the surrounding sand and the trough to its"landward side is frequently wide and. deep. This results in a further adjustment since broken waves are now progressing in deepening water rather than gradually shoaling water. The transla- tory waves created by breaking are sometimes able to reform into oscillatory waves and although a great deal of energy has been lost in the original breaking, the reformed wave may be as large as many of the smaller ones which passed over the bar without breaking; these waves break again on the inner bar. For this reason, practically all waves break on the inner bar with breakers which are much smaller than those on the outer bar; for those waves which break twice, the difference in height between the two breakers is a measure of the amount of energy expended in the outer breaking. (Note that the height of a breaker is proportional to the square root of the energy)." He also states: "Bars have been observed on beaches ranging in size, and subject to the wave action of, model tanks, lakes, seas and oceans. Many types and sizes have been described. Hagen (1#63J who first suggested their origin saw five on a single beach; Gilbert (1335-) mentions bars on the shores of Lake Michigan that could be traced for "hundreds of miles: (he probably did not mean that these bars were con- tinuous, but even so, it is quite remarkable)", » "The number of bars on a beach depends on the size of the waves, the general bottom slope and the tide range". If a way could be found to secure the bar offshore to insure *.'"*' *,* "» this natural process, it would thus provide a continual form « of coastal protection. Maintaining the profile of equilibrium on a beach is in direct relation to the establishment of offshore bars. "Dr. King° defined an offshore profile on a well-established sandy beach as a gradually flattening curve seaward built up by 'the action of the sea over a long period. When this profile has reached the stage of stability - that is,'when the'progradation, or the-building up of the beach, compensates for any retro- 5 gradation, or eroding away-it is usually termed the "profile of equilibrium", and thus it is the ultimate object in any reclamation - to restore the profile of equilibrium. It will be appreciated, therefore, that the restoration of such a profile rests largely on the restoration of the lower beach to its correct position and until such a stage is reached, any replenishment of the upper reaches would be of little avail".9 p. 50 The underwater mound tested at Durban, South Africa, was an example of a type of protection with this theory in .mind. The * • * construction of the mound was predicated by a change in water depth from 18 feet to 42 feet with the advent of ocean going vessels. This change took place from 1#95 to 1959. In their' . • . ..25report ., J.A. Zwamborn, G.A.W. Fromme, and J.B. FitzPatrick state: "This scheme consisted of dumping the spoil along a line parallel to the.beach line some 1,200 m offshore, in an attempt to form a continuous underwater sand ridge eventually of some 4.5 km long". "If such an underwater mound could be built up to a sufficient height and provided it would remain fairly . stable, it would act as a selective wave filter, e.g. low waves would pass unhindered, whereas large erosive waves would break on the mound and thus loose much of their energy. • As a result, beach building conditions were expected to improve in the lee of the mound and due to the reduction of the 'incident wave heights, longshore sand bar and trough dimensions were ex- pected to be reduced, resulting in safer bathing conditions". "Although underwater breakwaters have been built before for the protection of certain beach areas, particularly in Japan, the underwater mound scheme, when conceived in 1963, is believed to have been the first application of an artificially placed sand bar to protect the leeward beaches. Large amounts of sand are available from harbour dredging works at Durban but since trailing-suction dredges are used, it is impractical to discharge the sand directly onto the beaches. Nearshore dumping, in an attempt to feed the Beaches, was tried at Long Beach, New Jersey and Santa Barbara, California; both attempts were,, however, unsuccessful because the sand remained where it was dumped instead of moving onto the beach". The reasons for failure of the above mentioned dumping sites were related to the depth of water in relation to the placement o of the mound. In A^Kinmon^s report , it is stated: "It was proved conclusively that to be of .any • material assistance in shore reclamation, dumping of sand must take place within the "breaker" zone, that is, within the sphere of influence of the waves of translation For example, at the Long Branch, New Jersey experiments (1943 - 1949) sand was deposited , in 3# feet of water with, negative results. At Atlantic City (1935 - 1942) dumping in 15 to 25 feet depth of water was equally ineffective, while at Santa Barbara, California, (1935 - 1946) where the conditions generally ..were very similar to those, appertaining to Durban, the experiments failed to establish any accretion of sand when dumped within 20 feet depth of water". • . nf J.A. Zwamborn, G.A.W. Fromme, J.B. Fitzpatrick , in their paper, "Underwater Mound for the Protection of Durban's Beaches"- concluded that: n (a) An underwater mound of sand of the correct dimensions offers an effective beach protection scheme. (b) Such a mound of fine to medium.sand may be expected to remain virtually stable under most wave con- ditions and if losses occur during severe storms, natural processes will re-build the depleted mound to its. original size". In a paper by J.V7. Hall and W.J. Herron1^, entitled "Test of >--v Nourishment of the Shore By. Offshore Deposition of Sand", it is stated: "Since it has been shown that material moved in deep water but not toward the beach it might be well to : consider for a moment the conditions under which sand does move in quantity from the offshore area to the beach. Little is known of the boundaries of a move- ment of this nature. It is known that during storms when waves of high steepness are striking the beach, the beach erodes and the material is pulled seaward forming an offshore bar. It is knownfurther that when the wave steepness decreases, that is, when the wave height becomes small in comparison with the length the bar is moved onto the beach. It is evident from the findings of this test that the stockpile probably was outside the seaward boundary of this phenomenon. It appears from the above that if the sand had been placed in shallower water it might have been trans- ported to the beach. An attempt to nourish an eroding beach by dumping dredge spoil in 15 to 25 feet of water (mean low water] was made, by the Philadelphia District, Corps of Engineers. The results of the test are given in the following paragraph taken from a Beach Erosion Control Report on Cooperative Study of Atlantic City, New Jersey, approved April &, 1947. "Realizing that, augmented nourishment of the .beach would be beneficial, the sand removed'from the channel by dredging was released by hopper dredges in the waters southwest of the Steel Pier and as near the beach as the dredge could operate in the hope that the spoil so dis- charged would move ashore by natural underwater proces- ses. Evidence that any substantial quantity of sandmoved onto the beach .has not been found, despite the fact that 792,000 cubic yards of sand were so deposited off the beach in the period April 1935 - March 1936, nearly 900,000 cubic yards in February-September 1937,more than 500,000 cubic yards in August-December 193° and 1,362,000'cubic yards, in the period August 1942 - September 1942". Further a similar attempt at nourishment was made at Santa Barbara,' California, where 202,000 cubic yards of "sand were deposited by the hopper dredge in 20 feet of water (mean lower low water) in September 1935. The results are given in the Report on Cooperative Beach Erosion Study at Santa Barbara, California, District Engineer, Corps of Engineers, November 22, 1946 follows: "The mound deposited by hopper dredge in 1935 has remained exceptionally stable. The profiles indicate that its present ridge elevation of 17 to 1# feet -below mean lower low water is at no point more than a foot below the 1937 elevation. However, the shallow trough between the mound and the shoreward slope of the natural bottom has been filled to a depth of 2 to 3 feet in most places". "In view of the results of these studies, and espec- ially the Santa Barbara, California, study where the . .crest of the mound was near the surface and there is a large percentage of waves with low steepness which are conducive to a shoreward movement of material, it is evident that if material is to be transported . shoreward in any quantity it must be deposited in water shallower than that previously-empldyed. How ,much shallower cannot be determined from this study but it is probable that it would have.to be placed on or landward of the offshore bar". 15 Finally, V7. Bascon^states: '.""'. '.• "The importance of the "near shore" area in its influence upon beach erosion is therefore obvious, and there is no doubt that the movement of the beach material takes place largely within this zone, motivated by the in-shore currents and the littoral drift".* The importance of the littoral zone and littoral material in the rebuilding of an eroded beach, cannot be denied. W. Bascora states as follows: • . _ • . "Longshore currents need not be of sufficient'velocity themselves to pick up and transport sand, for in the surf zone the sand is put into suspension by the forces accompanying wave transformation and very small currents are effective in moving the suspended material sidewise. Wave steepness is an important factor in determining the rate of littoral drift. Higher waves effect the bottom deeper and keep the sand in suspension over a wider area; shorter period waves will be less refracted and strike, the beach at a greater angle. The volume of material transported is therefore seen to be'dependent on the height, period and attack angle of the waves as well as on the. • nature of the materials involved and the variations in the character of the zone of transport". "Man, in building shoreline structures that obstruct or influence littoral sand flows almost invariably creates a dual problem: (1) sand will deposit where- ever comparatively quiet water is created and (2) cut off the supply of sand to beaches downstream from . .the structure which will retreat". • The key word here is "obstruct". A system which would employ rather than obstruct thi's littoral flow to help create quiet »» • waters, seems to be feasible and workable. In many areas, groins have been employed as a means of en- ' • ' • '••.trapirg littoral sand, however, this practice is very often » destructive as many studies have shown. It is in fact generally accepted that groins alone are inadequate as coastal protection. Dr. Bruun^ adds credence to this theory in his paper "The History and Philosophy of Coastal Protection": "The evidence laid before us goes to show that in many cases on the coast of the- United Kingdom groins have .. been constructed of a greater height than was riecessary ' • to fulfil the required conditions, with the result that they have so unduly interfered with the travel of the shingle as to lead to impoverishment of the beach to leeward, causing in many districts serious injury to the coast" • ' ' 10 . o Groins built in the thirties on the Danish North Sea Coast caused erosion of up to 30 feet per year. Groins at Miami Beach are examples of this type of control measure, when used alone, resulting in inadequate coastal protection. A system which had proved to be successful in Holland because of the fact that currents combined with swell action provided the shore with material from offshore so that the groins were' not being starved has become a destructive system in many other cases. In Durban, South Africa, where the mentioned submerged- sand bar was built, groins constructed on the northern beaches have ' 9caused considerable erosion, as stated in A Kinraon^s report: "There is no doubt that eddy currents are being estab- lished in this vicinity, probably due to the imperm- eability of th6 -structure, and-the inability'-'of the waves to pass over, and a new aspect of the erosion •-problem has-been set up. Due to this depth of water, the normal gradients of the beach have, in turn, been disturbed, and the.sand is taking up an unusual pattern for inter-groyne build-up. Instead of accumulating on the southern face.of the groyne - the littoral drift being northerly - the sand is forming a central spit, and the areas on both sides of the groynes are being severely eroded, with consequent threat of movement . . of the structure itself, and, incidentally, the form- ation of dangerous bathing conditions". These groins were constructed during the period 1954 to 1956. ;: i The depth of water 'at the end of the groyne was originally 10 - 12 feet. After some five years, the depth of water was 11 30 feet. J.V. Hall, Jr.16, in his report "Artificially Nourished and Constructed Beaches" states: "I'ore importantly, there has developed a growing recognition of the fact that preventing erosion by means of protective structures is a dangerous practice, ir the sense that in many cases such protection is secured at the expense of producing an ever expanding problem area". Dr. Bruurr states: " It is generally accepted that groins aro able to slow down longshore drift but loss by trans- versal drift is probably far more severe, particularly on shores with steep offshore profiles". He further states: .' . » • -"Flexible defence costs less and mostly it is the most successful and it does not prohibit stand-by positions when needed". • This idea supports the Beachbuilder System. An unusual type of "flexible defense" was tested both in the laboratory and in the field. The first study was carried out by W.A. Price, K.W. Torn!inson, and J.N. Hunt, and the results of the study are reprinted in the Proceedings of the llth Conference on Coastal Engineering in their paper entitled "The Effect of Artificial Seaweed in Promoting the Build-up of* 6 • ' 'Beaches" "The paper describes tests carried .out in the lab- oratory and in the field in an attempt to discover 12 N ' . whether a field of artificial seaweed placed off- '. • ••• '£•* shore can promote an. offshore transport of bed- ^4' material arid hence a build-up of beach levels. Tests . .'*•!$. in a wave tank shov/ed that beach levels could be built : $*' up .in this way - the effect of the seaweed being to ' -:'&.$ increase the net drift of bed water in the direction of ' -^:*- • wave prorogation i.e. towards the shore.' The field trials : £^; were not as conclusive 'as was hoped, but nevertheless some .• .^';' 'build-up of the beach due to many stores night have been : v.:\£ anticipated". • '•• . , ' %iv. :. .Vi' In "Construction and Geotechnical Engineering Using Synthetic "•*;;} Fabrics", by Dr. Robert M. Koerner and Joseph P. V/elsh* it is £1 _*• t. stated: . • • */.;"•. „•» ••-•. -v."Inasmuch as vegetation slows the water runoff velocity on -^ slopes to be protected on land, undersea vegetation can •.*'.]•; slow water currents to the point whore all, or some, of •_. * the sediment being carried with it is deposited. ' By :«•"'. artificially creating such a situation under the sea at '•[' desirable locations a sandbank car. bo. buil't up, thereby eliminating possible erosion from occurring. Since erosion •-.'• and sco.ur are wellknown hazards to underwater construction, €his type of application of fabrics seems to be quite appealing". ' Case histories regarding types of artificial seaweed are sited. i ' ' . . •. • • Case 1. "Beginning in 1965 with an experimental planting £'• off the coast of Hew Jersey, Avisun, a subsidiary of Sun :>. Oil Co"., has developed and tested an artificial seaweed ,•> One year after installation The . :/< building of sand extended 6 to £ feat away from the base of .' the frond. Brashears and Dartnell write favorably on all aspects of the project but caution against the adequacy of the anchoring system". • Case 2. "For approximately ten years, artificial seaweed has been used to slow down ocean currents, thereby decreasing erosion and fostering deposition of sand and the eventual stabilization of problem areas. .'...Major testa t-* of the material, reported at the International Conference v of Coastal Engineering, indicate that...;.;.. .polypropylene ,f seaweed prevents erosion by tidal current once the artificial ''- seaweed field is introduced"-.^ One of the most dramatic tests i of the material was conducted off the Dutch Coast at the Leman-'. gas field near txvo drilling rigs working for Shell and Esso in the North Sea..... .After the material was laid it was • • 13 •' ' F» \» • : •*•;$inspected by divers 30 days later. The seaweed was reported jV^'-fc buried in the sand, which had built up around it, and th pit had been largely filled." Case 3. "The- system consists of polypropylene strand locked into a synthetic mat at half-meter intervals The first full-scale trial began in 1963 when a prototype was laid alongside of a 46-meter-long pipeline in 9 meters ,of water. Within a few months a 1.5-meter sandbank had 'accumulated over the whole protected area. -The pipeline was completely covered, although only a few meters away, • where tne system was not placed, it remained exposed". Dr. Koerner and Joseph Welsh site cases using different types* of artificial seaweed, all of which have had favorable results. These tests include oil drilling stabilization projects conducted'.'M^f off the Dutch Coast in the North Sea, and major tests reported at the International Conference of Coastal Engineering regarding the prevention of gullies in dune protection, the prevention of banks slides and the protection of submerged pipelines. Major companies such as*Sun Oil, I.C.I., Shell Oil and ESSO have been involved in these tests. f ". .*•-•-•." 'YC-Vv. '': :'•"*'£&& ' -.V-igfife Another test of "artificial seaweed" was conducted in 1965 ' in the State of New Jersey. Excerpts from the final report - : •Artificial Seaweed Installation Off Island Beach State Park,-.: ' ' ' ' ft'} vlI.'ev; Jersey by Clarence F. Wicker , are as follows: ' V:-a?>-.v- "The State of New Jersey and the Avisun~~>Corporatiori ' entered into a cooperative agreement for the experimental ?• installation of a field of so-called artificial seaweed -" in the Atlantic' Ocean off Island Beach State Park in the '. Spring of 1965. The experiment was justified by the .'v«'i>? findings of Professor H. Lundgren of the Coast and- Sea . •*>«-- 'Laboratory of the Polytechnical Institute in Denmark after his study of a similar installation by the Danish Gov- ernment. Apparently, the seaweed caused the deposition of sand, and Professor Lundgren considered the results to have been "very encouraging". ^ best laboratory for* making an investigation with 'a view to perfecting the design is the ocean itself. It is probably infeasible to conduct an ivestigation by means of model experiments. Further-more the system must be such as to resist effectively the complicated and greatly varying forces that are experienced in the ocean, and such a regimen is difficult to model ........... Only after a system is designed that will stay in place can it . be determined whether the seaweed material employed is effective in causing the accumulation of a shoal or of retarding erosion. It is useless to consider v;hether any kir.d--.of artificial- seav;ee4 is effective until a suitable anchoring system has been designed". Beachbuilders has designed such a system. Beachbuilders of America, Inc., uses a system of restoration by natural means, utilizing a 'flexible anti-erosion device placed in waters where shoreline erosion is occurring. The material v;orks on a principle similar to that of a snow fence. Sand in transport in the water is deflected downward by the undulation motion of the material where it collects to form a bar. The more active the water, the faster the sand collects. Gradually, a sand bar forms around the Beachbuilder. The sand bar, working as a natural buffer, effectively dissipates the destructive force of the waves before they hit shore. In time, the area, between the sand bar and shoreline fills with sand, extending the beach and its uses. 15 It is apparent that adequate testing of this concept has 'beer* done over the past decade - Beachbuilders is ready to put it to v/ork for you. ' .i 3Dr. Per Bruun so eloquently states: ""Coastal protection does not necessarily need to be just coastal defence. Old Dutch experience and military tradition seems to favour defence by attack. In a war it is always best to keep the initiative and not leave it to the enemy An American version of this experience may be expressed as "the best protection for real estate is plenty of real estate in front of the real estate you want.to protect" Per Bruun BEACHBUILDERS OF AMERICA," BIG. 16 Appendix SECRETARY FOR RESOURCES POLICY FOR 5HDRELINL EROSION PROTECTION (Established September 14, 1978 and Revised February 6, 1979) Introduction California's shorelines are subject to the natural, continuously changing effects of erosion and accretion caused by waves, current, and wind. In some instances, development has taken place, or is being proposed, in unstable erosion-prone areas which eventually may require remedial protection or even abandonment. Because the natural processes and human activities causing shoreline erosion do not respect political Jurisdictional boundaries. State guidance and coordinated agency policies are required. Remedial projects have been used along California shorelines with varying degrees of success. In some Instances, breakwaters, groins, seawalls, and revetments have created new problems because they were placed without a full understanding of the natural process of shoreline erosion. Remedial projects require large capital Investments and may significantly alter the configuration, appearance, and recreation potential of the shoreline. Projects designed to restore natural beach conditions by artificially h supplying sand may be a more desirable alternative. This type of remedial action, however, requires periodic renourishment and a continuing supply of sand. The cost to public and private property owners, the tragedy of homes lost by erosion, and the need for government relief and expensive remedial actions can be avoided if development is not allowed in geologically unsuitable areas, or in areas subject to sand depletion without natural replenishment, or to excessive erosion rates. Additionally, erosion problems might be forestalled or avoided by effective land use policies, especially In currently undeveloped areas and by not upsetting the delicate and ..atural balance of nature. Protecting coastal property values, maximizing the recreational potential of our shoreline by maintaining sandy beaches, protecting wildlife habitats, and protecting options for revenue-producing-activities are- objectives Of primary importance to the State of California. . The 1976 amendments to the Federal Coastal Zone Management Act require that coastal management programs include a planning process to assess tht effects of shoreline erosion, to study and evaluate ways to control or lessen the impact of erosion, and to restore areas adversely affected. The California Coastal Act of 1976 assigns primary responsibility for carrying out this program to the California Coastal Commission. The State flarhni** ^nd ' Navigation Code assigns the responsibility for studying shoreline fro«1an. for agvTJhng government agencies, for planning, designing, and construe^1*? shore arotpction unrkt, and for administering State funds for the local share of "federal projects to the Department of Navigation and Ocean Develppn*!nt,The » Public Resources Code assigns responsibility to the state Lands Commission for 77 -""**, and protecting State-owned mineral resources and mineral rights. jiougn these laws form the heart of California's shoreline erosion control program, many other agencies play key roles and must exercise their mandates and advisory functions in a consistent manner. This statempnt establishes the basic shoreline erosion control policies for all departments, boards, and commissions within the Resources Aoencv to use when developing projects, authorizing private or public projects, or commenting on permit actions taken by other authorities including federal, State, and local agencies. These policies should be applied by State agencies when taking the following actions: (1) Commenting on Environmental Impact Reports pursuant to the California Environmental Quality Act, Environmental Impact Statements pursuant to the National Environmental Policy Act, and U.S. Army Corps of Engineers and U.S. Coast Guard public notices; (2) Issuing California Department of Fish and Game stream or lake bed alteration agreements and State Lands Commission mineral extraction and tidel and leases; (3) Planning, designing, and carrying out Department of Water Resources projects, Department of Navigation and Ocean Development projects, State Water Resources Control Board projects, and In planning, purchasing, and improving state parks and beaches; (4) Considering coastal development and San Francisco Bay Conservation and Development Commission permits and certifications of consistency with the California Coastal Management Program under provision of Section 307 of the Coastal Zone Management Act; (5) Preparing and certifying Local Coastal Programs required by the California Coastal Act; (6) Granting Coastal Conservancy funds for mitigating shoreline problems; and "" (7) Reviewing mined-land reclamation plans and classifying and designating .significant mineral resources.1 » The effectiveness of these policies depends on the steps each department, ooard, and commission takes to carry them out. Agencies with administrative regulations affecting shoreline erosion should amend those regulations to incorporate these policies. Because the Local Coastal Programs (LCPs) required by the California Coastal Act offer a unique opportunity for local agencies to deal with shoreline erosion in an effective, coordinated, and 'arsighted way, each agency within the Resources Agency is directed to cooperate with the Coastal Commission and local governments by reviewing LCP work programs, offering technical assistance to identify Issues, and suggesting ways to address these Issues in carrying out the California Shoreline Protection Policies. " 78 ./***** CALIFORNIA SHORELINE EROSION PROTECTION POLICY Development of the lands adjacent to large bodies of water carries with it an element of danger from wave action, which can threaten the s:fety of public and private property and recreational values. It is the policy of the Resources Agency that the use of these lands avoid hazardous and costly situations caused by erosion and m1n1mize"or resolve existing problems. Only in those situations where structures or areas of public use are threatened should the State resort to funding or approving remedial projects. When necessary, projects should restore natural processes, retain shoreline characteristics, and provide recreational benefits to the extent possible. II. Planning and Regulation A. In planning for the use of land adjacent to the shoreline, State agencies shall assure the following: 1. Effective land use plans and regulations to prevent existing and future developments from being endangered by erosion of sand beaches or the base of bluffs; 2. Measures to reduce surface runoff, groundwater ef facts, and other activities that create bluff stability problems; 3. Measures for the orderly demolition or relocation of damaged or threatened structures and facilities and for the disposition of parcels of land that cannot be safely developed. B. Projects constructed within the coastal watersheds can Increase the natural shoreline erosion rates by blocking the flow of sediment to the shoreline. It is therefore the policy of the Resources Agency that developments planned, developed, or authorized by State agencies shall meet at least one of the following conditions: 1. The development, together with other adjacent developments allowed under local land- use regulations, will not reduce the natural sediment beyond that needed to adequately supply the shoreline; 2. Mitigation measures to Include providing an adequate sediment supply are included as a part of the project; or 3. A regional plan exists that would provide an adequate supply of sand to protect the shoreline, even if. the development 1s permitted. 79 Beach and dune sand, and similar sediment lying in riverbeds, estuaries, or in harbor channels, is a valuable resource that should be used for shoreline protection. It is, therefore, the policy of the Resources Agency that all such dredge or excavation material removed within the coastal zone or near-shore waters, which is suitable in quantity, sire, distribution, and chemical constituency, be discharged as follows: 1. Directly onto a natural beach in an appropriate manner for effective beach nourishment and in a manner to protect significant natural resources and the public use of such resources at those locations; or 2. When beach nourishment is not needed or appropriate at the time of dredging, the sand should be deposited at locations for eventual use for beach nourishment, provided that suitable locations are available and steps are taken to protect both significant natural resources and the public use of such resources at those locations; or 3. In those Instances where quantity, distribution, or chemical constituency of dredge or excavation material limit its use as described in paragraphs one and two, the material should be used to optimize its mineral values or its utility as construction material. D. Under California law, artificially induced shoreline accretions do not affect property boundaries. To preserve evidence of the position of public and private preconstruction boundaries, 1t shall be the policy of the Resources Agency that before approving any shoreline erosion control measure, a Record of Survey map shall be filed with the county, as prescribed in Section 8762 of the Land Surveyor's Act (Business and Professions Code Section 8762) and a copy furnished to the State Lands Commission showing at least the following: 1. An accurate positioning of the present, preconstruction, high-water line; 2. Sufficient ties to at least two existing record monuments, which will not be disturbed by proposed.construction; 2. The accurate position of any monument shown on a map filed in an office of public record, and which will be disturbed by the proposed construction, together with a plan to replace the monument in its original position or to provide Its position relative to nearby record monuments. The Jlannino and Improvement of parks and beaches should be done 1n a wav consistent with protection aoainst the potential erosion of _ d segment of the coastline, and any structures, in .areas subject to erosion damage should be expendable or moveable 80 jreline Protection Projects Shoreline protection projects are proposed by both private parties and public agencies. It 1s the policy of the Resources Agency that the following policies should be followed when evaluating project applications: A. Nourishment of beaches to protect against erosion shall be encouraged where the following conditions are met: 1. This does not conflict with significant living marine resources; 2. This will not result In adverse effects elsewhere on the coast; and 3. Measures are Included in the project to maintain the affected beaches In a nourished state. B. Construction of seawalls, revetments, breast*!-*, »>• ft artificial structures for coastal erosion control shall discouraged unless each of th* follow*^ 1. No other nonstructural alternative 1s practical or preferable; 2. The condition causing the problem Is site specific and not attributable to a general erosion trend, or the project reduces the need for a number of Individual projects and solves a regional erosion problem; 3. It can be shown that a structure(s) will successfully mitigate the effects of shoreline erosion and will not adversely affect adjacent or other sections of the shoreline; 4. There will be no reduction in public access, use. and enjoyment of the natural shoreline environment, and construction of a structure will preserve or provide access to related public recreational lands or facilities; 5. Any project-caused Impacts on fish and wildlife resources will be offset by adequate f1$h and wildlife preservation measures; and 6. The project is to protect existing development, public beaches, or a coastal -dependent use. No project shall be approved that will cause loss or destruction of State mineral resources or that will subject State Mineral rights to trespass. All royalty considerations shall be determined by tht State Lands Commission and Implemented pursuant to the terns of a permit or lease granted by the Commission. 81 xject Financing A. It shall be the policy of the Resources Agency to recommend State financial participation in shoreline erosion protection projects only when all of the following conditions are met: 1. The protection project considers the long-term effects of erosion on all adjacent coastline sections subjected to similar or related erosional mechanisms and takes into consideration the needs of the entire region; 2. Any project-caused impacts on fish and wildlife will be offset by adequate fish and wildlife preservation measures; 3. The public benefits including the long-term environmental, social, and economic effect of the project are found to be greater than the public costs. The coastal section to be protected should contain substantial and valuable public-owned lands or facilities of greater value than the cost of the • proposed project, or the protection scheme should provide, maintain, or improve the public use and enjoyment of the beach or shoreline; 4. The project plan should use nonstructural solutions such as beach nourishment as the recommended alternative or as a part of the recommended alternative, unless it is not feasible; 5. Public access is provided to the shoreline area where the protection project is to be carried out unless the area is unsafe. B. In an emergency situation when erosion is threatening structures. State agencies should respond Immediately by offering technical assistance for temporary protective actions. Assistance should first be directed to emergency situations involving public assets. s/ Huey 0. Johnson Secretary for Resources 82