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Home My WebLink About3307; CARLSBAD BLVD SHORE PROTECTION; EROSION CONTROL RECONNAISSANCE STUDY; 1990-05-01SECTION 103 SMALL PROJECT CARLSBAD BEACH EROSION CONTROL RECONNAISSANCE STUDY CARLSBAD, SAN DIEGO COUNTY, CALIFORNIA Prepared by U. S. Army Corps of Engineers Los Angeles District 300 North Los Angeles Street Los Angeles, California 90012 May 1990 TABLE OF CONTENTS Page Table of Contents. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i List of Figures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii List of Tables. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iv List of Appendices. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -o . . . . . . o. iv EXECUTIVE SUMMARY ............. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . V 1.O PURPOSE AND SCOPE OP THE REPORT. ..... . .......... .. ..... . 1 2.0 BACKGROUND.............................................. 1 2.1 Study Authority. • . . • • . . . . . . . . . • • . . . • . . . . • • . • • . . ........• 1 2.2 Study Purpose and Scope . . . • . . . . • . . . . . • . . • • • . . • . . • • • • •. • . . 1 2.3 Study Participants and Coordination ..................... 2 2.4 Previous Studies • • . . • . • . . . • • . • . . . . . • . • • . . • . • . . • . • . . . . . • . 2 3 .0 THE STUDY AREA. • . . ._. . • • • • • . • • • • • . . . . . • • • • . . . . . . • . • • • • • . • 2 3 .1 Location. • . . . • • • . • . . . • • • . • • . • . • . • • • . • • • . . • . • . . . . . . • • . . • . 2 3 .2 Study Area Description. • . . • . . . • . • • . • . . . . • • . • • • . . . • • • • • . • 4 4.0 PROBLEM IDENTIFICATION. • . • . . • • • . • . • • . • .......... • • • . . • • • 4 4.1 History of Storm Damage and Beach Erosion ..........•.• 4 4 .2 Environmental Overview. • . • • . . . . . • • • • • . • • • . . . • . • . • . . • • • • • 6 4 .3 ProblemAnalysis . . . . • . . . • . . . . . • . • . • • • • • . • . • . • • • . . . . • • • . • 9 4.4 Storm Damage Costs Without Project.. . • • . . . . . • • • • . • . • • •.. 9 4.5 Potential Benefits and Equivalent Project First Costs... 22 I 1 Page 5.0 CURRENT STATUS OF THE STUDY............................. 22 5.1 Work Remaining for Completion of the Study.............. 22 5.2 Local Sponsor's Request to Terminate the Reconnaissance Study. . . . ....... . . . . . . . . . . . . . . . . . . . . . . . . . 30 6.O CONCLUSIONS AND RECOMMENDATIONS ......................... 30 4 1]. List of Piqures Page Location Map. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Study Area.............................................. 5 change in Beach Profile at Station CRB, 100-year Event... 10 change in Beach Profile at-Station P-4, 100-year Event... ii change in Beach Profile at Station P-i, 100-year Event... 12 change in Beach Profile at Station P-2, 100-year Event... 13 change in Beach Profile at Station P-3, 100-year Event... 14 change in Beach Profile at Station CRB, 50-year Event... 15 change in Beach Profile at Station P-41 50-year Event... 16 io. change in Beach Profile at Station CRB, 10-year Event... 17 ii. change in Beach Profile at Station P-4, 10-year Event... 18 Road Damage and Beach Area Loss - 100-year Event........ 19 Road Damage and Beach Area Loss - 50-year Event........ 20 Road Damage and Beach Area Loss - 10-year Event........ 21 Wave Height versus Storm Frequency.. ..... . .... .........25 Wave Height versus Storm Damage ............. ...... ...... 26. Storm Damage versus Storm Frequency. .... ..... ...... ..... 27 Design Year versus Storm Damage ...... ...... ..... ........ 28 111 List of Tables Page Storm Damage Costs...... . . . . . ............•.. ............ 23 Annua]. Damage Costs...... . . . . .. . . . . . . ... . . .. . . . . ... . ... . 23 Annual Recreation Benefits.............................. 24 Potential Project Benefits and Equivalent First Costs... 29 List of Appendices Carlsbad City Council Resolution Damage/Erosion Cost Estimates Volume of Beach Loss Annual Damage Cost Estimates Operation & Maintenance Costs and Detour Cost City of Carlsbad's 7 February 1990 Letter iv EXECUTIVE SUMMARY On 23 February 1988 the Carlsbad City Council adopted a resolution formally requesting the U.S. Army Corps of Engineers, Los Angeles District, to undertake a reconnaissance and initial appraisal study of the beach erosion problem along Carlsbad Boulevard/State Highway 21 between the intake and outlet jetties of the Aqua Hedionda Lagoon. A Reconnaissance Assessment report was completed for the study area by the Corps of Engineers, Los Angeles District, in February 1989. The report recommended to continue the Reconnaissance Study under the local sponsorship of the City of Carlsbad. Funding to the amount of $100,000 was subsequently provided in May 1989 to the District to perform the Reconnaissance Study under Section 103 of the Continuing Authorities Program. This Report (a) provides the current status of the Carlsbad Beach Erosion Reconnaissance Study; (b) addresses the problem of storm damages to the causeway section of Carlsbad Boulevard/State Highway 21 between the intake and outlet jetties; and (c) gives an estimate of potential damage savings, recreation benefits and equivalent project first costs. The Reconnaissance Study was discontinued at the request of the local sponsor prior to plan formulation for alternative solutions to the storm damage and beach erosion problem and, therefore, no project cost data was developed for comparison with the potential benefits. Since the City of Carlsbad, the local sponsor, has recently completed a Feasibility Study of its own and is proceeding to the project design and implementation stage with potential state funding, and requested the Corps of Engineers not to continue the Reconnaissance Study, it is recommended that all further activities of the Study under Section 103 of the Continuing Authorities Program be discontinued. Further, it is recommended that this report represents the completion of the study effort under this program. v 1.0 PURPOSE AND SCOPE OF THE REPORT The purpose of this report is to present the results of the Carlsbad Beach Erosion Reconnaissance Study, City of Carlsbad, San Diego County, California, prepared under Section 103 of the Continuing Authorities Program. The report addresses, from reconnaissance - level studies, the problem of storm damages to the causeway section of Carlsbad Boulevard/State Highway 21 between the intake and outlet jetties of the Agua Hedionda Lagoon. Formulation of alternative plans are not addressed because the remaining studies were discontinued. 2.0 BACKGROUND 2.1 Study Authority The Carlsbad City Council adopted a resolution, No.88-49, on 23 February 1988, formally requesting the U.S. Army Corps of Engineers, Los Angeles District, to undertake the reconnaissance study under the Corps of Engineers' Continuing Authorities Program. 2.2 Study Purpose and Scope The purpose of the Reconnaissance Study is to assess the potential storm damage to the study area, develop and evaluate alternative storm damage prevention measures, and to determine the Federal interest in participating in a project at Carlsbad under the continuing Authorities Program. The study describes the storm damage and beach erosion problem and costs. Preliminary alternative solutions to the problem were to be developed and compared based on an appraisal of costs, benefits and environmental impacts, including a recommendation on the most economically justifiable and environmentally acceptable solution. 1 2.3 Study Participants and Coordination The local sponsor which requested this Reconnaissance Study is the City of Carlsbad. The local support organization is the Beach Erosion Action Committee (BEACh), consisting of the cities of Carlsbad, Del Mar, Encinitas, Oceanside, San Diego, and Solano Beach. The organization's objective is to protect, maintain and enhance the beaches and coastline of the member cities. 2.4 Previous Studies The Corps of Engineers, Los Angeles District, completed a Section 103 Small Project "Reconnaissance Assessment" report for the study area in February 1989. The report developed, and evaluated several preliminary alternative solutions and identified the groin-system alternative as the most feasible one with a benefit/cost ratio of 1.1 to 1.0. The report recommended that funds should be provided for continuation of studies to the Reconnaissance Study phase. In April 1989, the City of Carlsbad published a report on the "City of Carlsbad Proposal for the Carlsbad Beach Erosion Study and Coastal Shore Protection Project." This report recommends as a feasible solution a 2,200-foot long concrete-capped sheetpile seawall with revetments at both the north and south ends, which represents the local sponsor's desires. 3.0 THE STUDY AREA 3.1 Location The study area is a three-quarter mile segment of the shoreline between the intake and outlet jetties of the Agua Hedionda Lagoon within the City of Carlsbad, San Diego County, California. The area is located about six miles downcoast of Oceanside Beach and about 90 miles south of Los Angeles (Figure 1). The 3/4-mile coastal segment is a very narrow cobble beach fronting State Highway 21/Carlsbad Boulevard, which is one of the three major north-south thoroughfares serving the entire Northern San Diego County region's circulation system. 2 r CITY OF CARLSBAD .BUENA VISTA LAGOON - REGIONAL SHOPPING CENTER _ z PRIVATE HOMES 4 rn c, CA UI o BRIDGE GU HEDION STUDY AREA LA S. G.& E. POWER PLANT PRIVATE HOMES: (ENCINAS CREEK BRIDGE :m ENCINA SEWER PLANT STATE CAMPGROUPIO 0 DUAL BRIDGES BATI ITOS AGO FUTURE STATE BEACH PARKING LOT \, (NEVADA IUTAH C' *ai f*NCISC0 LOS ANGICLES.- • % C3iPLSBPD PRQJ(CT LXATKW/ XI CO V VICINITY MAP Wa SCALE —_— i_ j MILES Figure 1. Location Map 3.2 Study Area Description The study area includes the 4-lane divided causeway-Carlsbad Boulevard completed in 1989; with an automobile parking area between the sand dunes and the lagoon on the east side, parallel curb parking on the west side of the road, and a narrow strip of beach. Almost every year, winter storms strip away the thin layer of sand from the Summer swells and sand transport, leaving a discontinuous layer of sand cobbles on the beach. A visit to the site on 13 July 1989 revealed that there was virtually no beach along the northern 25 percent of the reach adjacent to the intake jetties, while the beach gradually widens to about 150 feet just north of the southern outlet jetties. The beach is used for public recreation, including swimming, surfing and fishing. East of the immediate study area are the Atchison Topeka and Santa Fe Rail Line, San Diego Freeway and an inner lagoon (Figure 2). South of the area are the San Diego Gas and Electric Company's power plant and more beach area. Immediately north of the study area across the intake jetties is a public parking lot with approximately 400 parking spaces and Carlsbad State Beach on the west of the boulevard and residential and commercial developments on the east side. The Agua Hedionda Lagoon serves a multitude of uses; including a body of cooling water for the adjacent power plant, research area, fishing, and feeding spot for wildlife. On both ends of the causeway are ripraps, rocks ranging in size from one-quarter to one ton, about 350 to 400 feet long from the intake and outlet jetties. 4.0 PROBLEM IDENTIFICATION 4.1 History of Storm Damage and Beach Erosion The study area is susceptible to coastal storm flooding, which results in damage to adjacent parking areas, undercutting the highway foundation material, and requiring debris removal as well as traffic detours along the highway. Severe erosion has occurred along this shoreline with damages to both public and private property. In recent history, the area has been damaged and the highway closed on the order of once every two years. The worst extent of damage occurred in the spring of 1981 when the highway was closed for 5 days and 200 paved perpendicular parking spaces were lost to erosion. It is estimated that the areal extent of erosional damages for this event was two-thirds 4 -- - /..:. ¼- \54• A. OF or joo if ML )- : IkC CP ';c--- -' •L - o' •• ' / A •.' . • ' .•c •' •M7 , • ell —.'; , •— •._—,;--- •,- • rc • - )Y • •••—' :. v' - - 9. T- -_/• • 00, do" le Ip 2 • • -• I. • ' a 1/2 • 1 mile • ,/ p. ,// •,•/ .••••- / •,• • Figure 2. Study Area 5 of the lengths between the two jetties (or about 2,000 feet) with an encroachment distance of about 100 feet. Flooding and debris deposited on the road was concentrated in the low-elevation areas over an extent of about 700 feet. Replacement value for the lost parking, including fill and pavement, approximated $500,000 (at $2.50/sf for 200,000 sf). The double perpendicular parking which was lost in 1981 was not totally replaced, but instead was replaced with a single row of angled parking. The angled parking was lost in the 1983 storm season, to the extent of about 100,000 sf and replacement cost of $250,000. The lost parking was subsequently replaced with parallel parking which exists today. The January 1988 storm did not seriously affect the parking areas but created a debris hazard and produced damages to the riprap around the bridge and road shoulder. About $20,000 was spent on clean-up during the 1988 storms. In addition, because of the storm damage to the roadway and the resultant highway closure in this area during the storms, all traffic, including private and public safety and emergency response vehicles, had to be re- routed, causing great inconvenience and loss of time (due to extra travel time) to the general public and interruption of critical public services. In view of the vital importance of Carlsbad Boulevard to the regional circulation system of both the City of Carlsbad and the northern portion of San Diego County, and since it is not practical or cost effective to close or relocate the highway, measures to protect the highway are needed. 4.2 Environmental Overview 4.2.1 Biological Resources a. Vegetation Coastal Strand is the only plant community located on the project site. The beach itself has no vegetation on it, aside from some kelp which was washed ashore. At the far north end of the beach, growing above the revetment structure is some ice plant (Carpobrotus edulis). The coastal strand community is located on the strip of dunes to the east. The Coastal Strand community has a variety of plants located on an east-facing slope which runs parallel to the Aqua Hedionda Lagoon. At the north end of the vegetation strip the dominant 6 plant is ice plant. Also located in the area are patches of Haplopappus venetus, Lotus scoparius, Camissonia cheiranthiflora, Frankenia grandiflora, and one unidentified flowering plant. In addition, small patches of sea rocket (Cakile maritima) also exist in the area. Running between the strand of dunes and the lagoon is a small parking area. At the south entrance to this parking lot are several unidentified shrubs, which are probably ornamentals. Once past the entrance to the parking lot, ice plant, sea rocket, and the unidentified white flowering plant dominate. The ice plant grows along the entire slope of the dune, while the sea rocket appears most commonly on the slope and the crest of the dune adjacent to Carlsbad Boulevard. The unidentified plant is found mainly at the base of the dune and interspersed with this are patches of salt grass (Distichlis spicata). The salt grass appears with the sea rocket at the crest of the dune along the road. Toward the end of this strip the slope of the dune flattens and the ground becomes level. Located on this site are ice plant, sea rocket, a few unidentified ornamental shrubs, the unidentified flowering plant, and tree tobacco (Nicotiana glauca). b. Wildlife A variety of migrant and resident shorebirds inhabit both the strip of beach and the Agua Hedionda Lagoon. Several species of birds were also seen along the far southern strip of the sandy dune. Along the shore marbled godwits (Limosa fedoa), willets (Catoptrophorus semipalmatus), and western sandpipers (Calidris mauri) were foraging. Also located along the beach were several varieties of gulls including the western gull (Larus occidentalis), Heerman' s gull (Larus heermanni), and the ringbilled gull (Larus delawarensis). Brown pelicans (Pelecanus occidentalis), terns (Sterna sp.), and cormorants (Phalacrocorax sp.) were seen flying over the project area. Pelicans and cormorants were also found roosting on floating dredge pipes in the lagoon. Also seen in the lagoon were willets and a few ducks. Various species of sparrows were observed on the southern end of the sand dunes adjacent to the Encina Power Plant. Brewer's blackbirds (Euphagus cyanocephalus), mourning doves (Zenaida macroura), and rock doves (Columba livia), were located on power lines along the power plant. California ground squirrels (Citellus beecheyi) were seen in riprap located both at the southern end of the beach and at the northern end of the lagoon along the sandy dune area. While examining the various plants located along the sandy dunes, several lizards were observed. 7 The Center for Marine Studies at San Diego State University is working on growing eel grass and kelp in the Agua Hedionda Lagoon, and both Occidental College and the National Marine and Fisheries Service are involved in halibut studies. In addition, Sea Farms West, a private firm, is involved in the mariculture of mussels and clams. It appears that previous storms and subsequent damage to Carlsbad Boulevard have no adverse effect on either the lagoon or the projects within it. On occasion both debris and water have been washed into the area but this has not affected the research taking place. 4.2.2 Air Quality and Noise No serious air quality problems occur in the Carlsbad area, although sources of pollution exist. Pollution sources include automotive exhaust and emissions from the San Diego Gas and Electric Company's power plant. Sources of noise in the area include vehicular traffic on Highway 21 and trains on the Sante Fe Rail Line. 4.2.3 Water Resources The two bodies of water of concern in the study area are the Pacific Ocean and Agua Hedionda Lagoon. The Lagoon serves a number of uses, including a body of cooling water for the electric power plant, research area, fishing, and feeding spot for wildlife. The Pacific Ocean in the vicinity is used for recreation, and by fish and wildlife. Water quality in the immediate vicinity is comparable to the surrounding area. 4.2.4 Cultural Resources The latest version of the National Register of Historic Places has been referenced along with related cultural resources data for the study area, and the results indicate that within the study area there are no sites listed or determined eligible for inclusion in the Register. A survey of the area by Bradley L. Sturm, staff Archeologist, determined that no historic properties are visible within the Area of Potential Effects (APE). However, formal coordination with the State Historic Preservation Officer will be necessary regarding a determination that any project proposed for the study area will not involve historic properties. 8 4.3 Problem Analysis The existing riprap on the north end of the highway near the intake jetties is not adequate to prevent storm damage during severe storms with high tides. Figures 3 through 7 show the potential damage to Carlsbad Boulevard at stations CRB and P-4 and no damage at stations P-1, P-2 and P-3 for 100-year storm events. A lesser degree of damage is expected at stations CRB and P-4 for 50-year (Figures 8 and 9) and 10-year storm events (Figures 10 and 11). The extent (i.e. the length of Carlsbad Boulevard) of damage expected for the 100-year, 50-year and 10-year storm events is approximately 480 feet, 410 feet and 300 feet respectively, southward from the south jetty of the inlet (Figures 12, 13 and 14). The beach area lost due to these storm events is also shown. No damage to the road is expected from lesser-frequency storm events. (Note: Stations P-1, P-2, P-3 and P-4 were established by the City of Carlsbad and Station CRB is a Corps of Engineers' reference point for the purpose of this study only) 4.4 Storm Damage Without Project Without a storm protection improvement project, the study area will suffer the following damages, costs and loss of recreation benefits: Road damage replacement costs of $175,699, $115,872 and $26,733 are estimated for the 100-year, 50-year and 10-year storm events (Table 1). Beach erosion replacement costs of $95,000 $10,845 and $3,000 (Table 1) are necessary for the 100-year, 50-year and 10- year storm events, just to bring the beach to its original configuration. It is assumed that sand needed for this purpose will be available from the Agua Hedionda Lagoon. (C) Operation and Maintenance costs of $9,000 per year on the causeway for the 100-year event (Appendix 4). Detour cost of $11,880 per year on extra travel time due to closure of the storm-damaged causeway (Appendix 4). Loss of recreation benefits estimated at $77,101. for the 100-year event (Table 3). -10 -50 CARLSBAD. CRB - CHANGE IN BEACH PROFILE elevation, 0 is MLLW 100 YEAR EVENT 30 + _:=_ revetment _..:.. 0 50 100 150 200 250 distance from center line, ft 300 350 - surface elevation 100 yr sea level 100 yr profile X-ÔRIGIN PLOTTED FROM CENTER OF CARLSBAD BO U L E V A R D -10 - -50 elevation, 0 is MLLW 30 20 'Ii] [i revetment _ 0 50 . 100 150 200 250 distance from center line, ft 100 YEAR EVENT 300 350 CARLSBAD . * P-4 CHANGE IN BEACH PROFILE - surface elevation 100 yr sea level 100 yr profile X—ORIGIN PLOTTED FROM CENTER OF CARLSBAD BOULEVA R D one 0 50 100 150 200 250 distance from center line, ft -50 300 350 CARLSBAD P-i CHANGE IN BEACH PROFILE elevation, 0 is MLLW 100 YEAR EVENT 30 IiI 10 100 yr profile - surface elevation 100 yr sea level X-ORIGIN PLOTTED FROM CENTER OF CARLSBAD BOULEVARD 1 CARLSBAD P-2 CHANGE IN BEACH PROFILE 100 YEAR EVENT elevation, 0 is MLLW 30 CD U) 0 rP r1 I-• 0 -10- -50 0 50 100 150 200 250 300 350 distance from center line, ft - surface elevation 100 yr sea level WM X-ORIGIN PLOTTED FROM CENTER OF CARLSBAD BOULEVARD -10 ,-- -50 elevation, 0 is MLLW 30 20 10 -A. <: 3*=—= r e V e t rMy' e n t 100 yr profile 0 50 100 150 200 250 300 350 400 450 distance from center line, ft 100 YEAR EVENT CARLSBAD •... P-3 CHANGE IN BEACH PROFILE surface elevation 100 yr sea level X-ORIGIN PLOTTED FROM CENTER OF CARLSBAD BOULEVA R D mim CL Ol Cl) p) ' _& ,, 0 (Do —h 1 0 a' 00 CD CD r-3 =0 D .4 1%3 —a' 0 C) 0 0 C;) 01 0 uaa iaA-O 'U3 UOt9 eTT01d Lj3 UT 96U43 8 eiTtbT I 10 a' 0 -h C;) 0 0 0 0 + I -S CD - CD CD _ _.1 •• CD CD 0 PC 0 Ii ;. oJ - I- I > z cn o m mm <uJc1J m 0 -D DD 0 -Ti F— m -10 -50 elevation, 0 is MLLW 30 10 R + T revetment 0 50 100 150 200 250 distance from center line, ft 50 YEAR EVENT 300 350 pj II CD CARLSBAD •.•• P-4 CHANGE IN BEACH PROFILE surface elevation 50 yr sea level 50 yr profile X-ORIGIN PLOTTED FROM CENTER OF CARLSBAD BOULEVARD CARLSBAD ORB- CHANGE IN BEACH PROFI L E elevation, 0 is MLLW 10 YEAR EVENT 301 + 20 10 revetment _10 I V II I I I I -50 0 50 100 150 200 250 -distance from center line, ft - surface elevation 10 yr sea level X-ORIGIN PLOTTED FROM CENTE R O F C A R L S B A D B O U L E V A R D 300 350 10 yr profile Ph CARLSBAD P-4 CHANGE IN BEACH PROFILE 10 YEAR EVENT elevation, 0 is MLLW CD P. 20 0 10 P. H H - co CD rt rt rt P. En 0. -50 0 50 100 150 200 250 300 350 H distance from center line, ft surface elevation 10 yr sea level 10 yr profile X-ORIGIN PLOTTED FROM CENTER OF CARLSBAD BOULEVARD rP Table 1 summarizes the total damage/erosion cost and the annual cost for the 100-year, 50-year and 10-year storm events without project, while Table 2 shows that the annual damage cost for the 100-year event is estimated at $42,503. Although the existing beach area of approximately 217,650 square feet may be able to accommodate 2,902 persons at any one time, the number of visitors that may be expected is only about 900 on a weekend day and 450 persons on a weekday because the number of parking spaces available in the study area is very limited. Therefore, in order to estimate the loss of recreation benefits due to various storm events, such a loss should be related to the loss of parking spaces since the number of weekend visitors (which is higher than the number of weekday visitors) in the worst scenario of a 100-year storm even can still be accommodated in the beach area remaining after the storm. Table 3 shows that an annual recreation benefit loss of $77,101 can be expected from a 100-year event. Figures 15 through 18 show the relationships between the wave heights and storm frequencies and related damage costs, and between damage costs and storm frequencies/design years, based on the above analysis. 4.5 Potential Benefits and Equivalent Project First Costs Potential benefits that could result from efficient storm damage protection measures and the equivalent project first costs, taking into account 100% and 49% of the recreation benefits respectively, for the 100-year, 50-year and 10-year events are presented in Table 4. 5.0 CURRENT STATUS OF THE STUDY 5.1 Work Remaining for Completion of the Reconnaissance Study The foregoing chapters present the existing problems and potential benefits with a project. Uncompleted studies at the reconnaissance level include the development of alternative protective measures, plan formulation, and determination of Federal interest in the project. Possible alternative solutions to the localized storm damage and erosion problem at the northern section of the highway are a seawall, a revetment, and a seawall - revetment combination. 22 Table 1. Storm Damage Costs STORM DAMAGE 100-YEAR 50-YEAR 10-YEAR Road Damage $ ----------------------------------------------------------- 175,699 $ 115,872 $ 26,733 Beach Erosion $ 95,000 $ 10,845 $ 3,000 Total Cost:* .$ ---------------------------------------------------------- ----------------------------------------------------------- 270,699 $ 126,717 $ 29,733 Annual Cost:** $ ----------------------------------------------------------- 21,623 $ 19,636 S 13,378 Table 2. Annual Damage Cost Annual Cost Damage 100 - Year 50-Year 10-Year Damage/Erosion $ 21,600 19,600 13,400 O & M (Operation & Maintenance) $ 91000 *** 9,000 4,500 Detour $ 11,900 *** 11,900 6,000 Total Annual Damage Cost: $ 42,500 40,500 23,900 * See Appendix 3 ** See Appendix 4 *** See Appendix 5 23 Table Y. Annual Recreation Benefits Existing 100-year Event 50-year Event 10-year Event Loss * Ranain. Loss * Reiain. LOSS* pj1 Beach Area (square feet) 217,650 133,400 84,250 19,950 197,700 6,750 210,900 No. of Persons 2,902 1,779 1,123 266 2.,636 90 2,812 that can be accommodated / (at 75sf/pers) I No. of Parking 150 33 117 28 122 20 130 Spaces (parallel street pkg at 15 LF per car) No. of Visitors 900 198 702 168 732 120 780 per weekend-day (3 pers/car x turnover 2) No. of Visitors 450 99 351 84 3661 60 390 per week-day 1 (3 pers/car) No. of Visitors! year 106,200 23,364 - 19,824 - 14,160 - (Item 4x53)+(Item 5x130) ** Recreation Benefits/year $350,460 $77,101 - $65,419 - $46.728 -. (Item 6x $3.30) * Loss of recreation benefits due to a given storm event. **Based on a beach us.e peçiod of April through September, i.e. 53 weekend days and 130 weekdays. CARLSBAD PROJECT WAVE HEIGHT vs FREQUENCY 12 10 W A 8 E H G H T 4 f t 10.80 10.18 9.45 8.181 2 o t I 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 08 0.9 1 FREQUENCY wave height with respect to MLLW Fiure 15. Wave Height versus Storm Frequency 25 CARLSBAD PROJECT WAVE HEIGHT vs DAMAGE 12 10.801 10.18 10 8 E- H G H T 4 f t V 8.18 2 .0 1 I I I I I I I 0 30 60 90 120 150 180 210 240 270 DAMAGE $ (thousands) wave height with respect to MLLW Figure 16. Wave Height versus Storm Damage 26 CARLSBAD PROJECT DAMAGE vs FREQUENCY 250 D. 200 G E $ 150 t h 100• 50 $270699 $126717 $29733 0 I I I I I .1• 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 FREQUENCY Figure 17. Storm Damage versus Storm Frequency 17 CARLSBAD PROJECT DESIGN YEAR vs DAMAGE 120 100 80 S I G N 60 Y E 40 20 rjT 100 50 10 I I I 0 30 60 90 120 150 180 210 240 270 DAMAGE $ (thousands) Figure 18. Design Year versus Storm Damage 28 . Table 4. ,Potential Project Benefits and Equivalent First Coats 100-'year Event 50-year Event 10-year Event Type of Savings With 1007A With 49% With 100% With 49% With 1001 With 491 Recreation Recreation Recreation Recreation Recreation Recreation Potential Damage Savings $ 42,5Q0 $ 42,500 $ 40,500 $ 40,500 $ 23.900 $ 23.900 Potential áeoreation Benefits 77,1O0' 40,800 65,400 38,900 46,200 23,000 Total Benefits 119,600 83,300 115,900 79,400 70,100 46,900 Equivalent Project First Costs $ 1,329,000 $ 925,600 $ 1,297,800 $ 882,200 $ 778,900 $ 521,000 For each alternative, the construction and operational and maintenance (O&M) costs would be compared with the benefits it provides, along with an environmental impact assessment. The economic analysis and the resulting benefit/cost ratio would provide a basis for the determination of justification for a Federal interest in a selected or recommended alternative. The alternative plan formulation and reviews will involve continued Corps of Engineers' coordination with and participation of local and regional interests. 5.2 Local Sponsor's Request to Terminate the Reconnaissance Study The City of Carlsbad has a recent feasibility study, prepared by a private consultant, and reached an agreement with the State of California Department of Boating and Waterways for state funding for the design of the project. The City, therefore, has requested the Corps of Engineers not to continue with the Section 103 Reconnaissance Study (See Appendix 5, City of Carlsbad's 7 February 1990 letter). 6.0 CONCLUSIONS AND RECOMMENDATIONS The Reconnaissance Study was discontinued prior to plan formulation for alternative solutions to the storm damage and beach erosion problem. Therefore, no project cost data was developed for comparison with the benefits. Equivalent project first costs were developed from benefits that could accrue from 10-, 50-, and 100-year levels of protection. Since the City of Carlsbad, the local sponsor, has recently completed a Feasibility Study of its own and is proceeding to the project design and implementation stage with potential state funding, and requested the Corps of Engineers not to continue the Reconnaissance Study, it is recommended that all further activities of the Study under Section 103 of the Continuing Authorities Program be discontinued. Further, it is recommended that this report represents the completion of the study effort under this program. A P P E N D I C E S 1200 ELM AVENUE CARLSBAD, CA 92008-1989 011lce of the City Manager TELEPHONE (619) 438-5561 QCitp of QCarIbab February 25, 1988 Colonel Tadahiko Ono, District Engineer U. S. Army Corps of Engineers 300 North Los Angeles Street Los Angeles, California 90053 Dear Colonel Ono: On February 23, 1988, the Carlsbad City Council adopted the attached Resolution No. 88-49 formally requesting the U. S. Army Corps of Engineers, Los Angeles District Office, undertake the reconnaissance and, initial appraisal study under the Corps' "Continuing Authority Program," Section 103 "Small Beach Erosion Control Program" for a potential project to protect Carlsbad Boulevard south of Tamarack Avenue within the city of Carlsbad. The assistance of the U. S. Army Corps of Engineers, Los Angeles District Office, in this effort is respectfully requested. The City of Carlsbad is available to assist the Corps in this study effort. Please have your staff contact Mr. John Cahill, of City staff, at (619) 438-1161 to coordinate this program. I would like to take this sincere appreciation for your be Of •ny further assistance, UDE A. LEWIS Mayor CAL:JJC:mjd Attachment opportunity to express the City's attention to this matter. If I can please call me at (619) 434-2830. c: Robert Page, Assistant Secretary of the Army, John Doyle, Deputy Assistant Secretary of the Major General Henry J. Hatch, Director, Civil Corps of Engineers Congressman Ron Packard Senator Pete Wilson Carlsbad City Council Members Civil Works Army, Civil Works Works, U.S. Army Appendix 3. (continued) RESOLUTION NO. 88-49 A RESOLUTION OF THE CITY COUNCIL OF THE CITY OF CARLSBAD, CALIFORNIA, REQUESTING THE U.S. ARMY CORPS OF ENGINEERS TO PROCEED WITH AN INITIAL APPRAISAL STUDY FOR POTENTIAL PARTICIPATION IN A PROJECT TO PROTECT CARLSBAD BOULEVARD SOUTH OF TAMARACK AVENUE WHEREAS, the-City-of Carlsbad owns, maintains, and operates Carlsbad Boulevard, a section of U.S. Highway 101 and a vital circulation arterial of local and regional importance; and WHEREAS, historically, Carlsbad Boulevard south of Tamarack Avenue within the city of Carlsbad washes out and is otherwise continuously damaged and temporarily inoperable during periods of severe winter storms; and WHEREAS, the recent storm of January 16, 17, and 18, 1988, further damaged this highway resulting in its temporary closure, loss of vital public parking facilities, and continuing and expensive repairs and maintenance; and WHEREAS, the U.S. Army Corps of Engineers, under its "Continuing Authority Program," sponsors a Section 103 "Small Beach Erosion Control Program" designed to address potential projects in which essential public services, such as transportation and. circulation systems, -are damaged or threatened by ongoing natural processes; and - WHEREAS, the City of Carlsbad's proposed improvements to Carlsbad Boulevard south of Tamarack Avenue require a more structured and permanent method of protection of the roadway to preserve essential local and regional circulation needs; and WHEREAS, the aforementioned U.S. Army Corps of Engineers program may include the opportunity to assist the City of :1. 2 3 4 5 6 7 8 9 10 1]. 12 13 14 15 16 17 18 19 20 21 22 231 241 251 26 27 '4' . . Appendix 1 (continued).. 1 Carlsbad's needs to provide a more structured and permanent 2 method of protection for the installation of the aforementioned roadway; and WHEREAS, the City Council of the City of Carlsbad finds it necessary, desirable, and in the public interest to request the 6 assistance of the U.S. Army Corps of Engineers in determining and funding a long-term solution to this problem; 8 NOW, THEREFORE, BE IT RESOLVED by the City Council of the City of Carlsbad, California, as follows: 10 . 1. That the above recitations are true and correct. 2. That the City Council of the City of Carlsbad hereby 12 formally requests the U.S. Army Corps of Engineers, Los Angeles 13 District Office, to undertake the reconnaissance and. initial 14 appraisal study of a potential project to protect Carlsbad 15 Boulevard south of Tamarack Avenue within the city of Carlsbad 16 under the District's "Continuing Authority Program," 17 specifically its Section 103 "Small Beach Erosion Control 18 Program." 19 3. That the City Council of the City of Carlsbad hereby 20 determines the aforementioned section of Carlsbad Boulevard 21 which is the subject of this request to be of vital importance 22 to the transportation and circulation system of this area. 23 24 25 26 . . ,27 I/I Appendix 1 (continued) :1. 2 3 4 5 6 7 8 10 11 12 13 14 15 16 18 19 20 21. 22 23 24 25 26 \27 28 4. That the City Council of the City of Carlsbad hereby offers its assistance and support for the U.S. Army Corps of Engineers' involvement in this potential project. PASSED, APPROVED AND ADOPTED at a regular meeting of the Carlsbad City Council held on the 23rd • day of February , 1988, by the following vote, to wit: • AYES: Council Members Lewis, Kuichin, Pettine, Namaux and Larson NOES: None ABSENT: None :' ZW :. dLAUDE A. LEWIS, Mayor ATTEST: J1L4Z d. ALETHA L. RAUTENKRANZ, City JClerk (SEAL) • - Appendix 2 Damage/Erosion Cost Estimates Storm Event 100-year 50-year 10-year a. Road Damage: Storm drain 1,160 928 696 Backfill 74,667 48,593 1.333 Aggregate 5,685 3,910 1,543 A.C. Pavement 11,426 7,858 3,101 S. Shoulder/riprap 2,880 2,460 1,800 Excavation 69,689 45,35 16,593 Sidewalk 247 211 154 Subtotal 165,754 109,313 25,220 S/A6% 9,945 6,559 1,513 Total 175,699 115,872 26,733 . b. Beach Erosion: - 1. Sand Replan. 95,000 .10,845 3,000 Total. 270,699 126,717 29,733 Volume of Beach Loss in the Study Area 100-year 50-year L.F. ear 10-y C.F./L.Y. C.P. C.P./L.F. C.F. CJ./L.F. C.F. 300 122.83 36,849 50.36 3.5,108 31.46 9,438 455 156.80 71,344 95.49 43,448 14.79 6,729 690 207.04 142.858 - - - - 700 170.63 119,441 - - - - 480 296.72 142,426 Vo1.C? 512,918 • 58,556 16,167 Cy 19,000 2,169 600 Cost $ 95,000 $ 10,845 $ 3,000 I * Assuming $5.00/Cl and sand being available from Agua liedionda Lagoon. Appendix 3 Annual Damage Cost Estimates CALCULATION OF AVERAGE ANNUAL DAMAGES BASIN REACH ILT RI. I TRIBUTARY UPSTREAM LIMIT OF REACH TYPE OF DAMAGE STREAM DOWNSTREAM LIMIT OF REACH PRICE LEVEL 1cOHOIT IONS1 REFERENCE POINT ID. A. 1COMP BY f DATE 1CHXD BY I•OATE FLOOD -fl) DISCHARGE (cs) (2) STAGE (Ft.) FREQUENCY DAMAGES (Dollars) AVE. ANNUAL DAMAGES RF (3) MSL (4) 44- (5) Interval (6) At Stage • (7) Average (8) Interval (9) Summa?ion (10) 100 01. 27OSN 21,623 i8,708 1,87 '..I _ O _ 02 127I7 . 78,22 6258 10 1 Z?,733 I3,'378 I4,8 G4 r3,7S I 1•O • REMARKS. -. Section 103 Small Project Carlsbad Beach Erosion Control Reconnaissance Study Appendix 4 Operation & Maintenance Cost Data from the City of Carlsbad indicates that the causeway segment (about 2,400 feet) of Carlsbad Boulevard in the study area suffers storm-related damages (operations, main- tenance, clean-up) at an annual cost to the City of Carlsbad and State of California of $45,000. For the 100-year event with damage to a 480-foot segment, the O&M annual cost would be $9,000. Detour Cost Closure of the causeway during severe storms and subsequent repair operations forces traffic to detour inland away from the coast. This affects about 16,500 vehicles per 24-hour period. The detour length is 2.4 miles. Data from the City of Carlsbad indicates causeway closure of an average of two days per year over the last 10 years. The El Nino series of storms closed the causeway for 5 days. Assuming the causeway to be closed an average of-.3 days/year and a detour time of 4 minutes per vehicle, the gross average annual detour cost = 16,500 cars/day x 2.4 miles x 3 days x 10 cents/mile. = $11,880. Appendix 5 City of Carlsbad February 7, 1990 Donald G. Spencer U.S. Army Corps of Engineers Los Angeles District Coastal Resources Branch. 300 N. Los Angeles Street Los Angeles, CA 90012 Dear Mr. Spencer: Your telephdne call' yesterday. afternoon regarding a Corps of Engineer's site visit to the proposed "small project" Carlsbad Shore Protection Project area precipitated some thinking here in Carlsbad regarding the potential financing alternatives and timing for a proposed project. Last, evening, the Carlsbad City Council adopted a resolution and approved an agreement with the State of California Department of Boating and Waterways for the State. of California's reimbursement funding for an analysis of design alternatives and formal design of a structural method of protecting Carlsbad Boulevard. This State funded effort is the identical project that the Corps of Engineers is working on regarding the "small project" request by Carlsbad. In short, it appears that State Boating and Waterways has approved funding the design of the project and has indicated the strong potential for funding the construction in the next year. We wish to notify the Corps of Engineers regarding the State's approval of funding for the project at the earliest opportunity so that the Corps will not proceed with any wasted effort and expense on the project. Please advise if a more formal notice from the City is necessary such as a Council Resolution or some other official notification. Thank you for your assistance in this matter. Please feel free to call me at (619) 438-1161 if I can provide any additional information or assistance. Sincerely , ours, / ,r em I/yi1 , (jL I1yLt' JOHWJ .eAHILL Municipal Projects Manager C: City Manager. Community Development Director City Engineer Pat Entezari, Project Manager 2075 Las Palmas Drive Carlsbad, California 92009-4859.(619) 438-1161