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Located in San Pedro Bay, the San Pedro Breakwater, with the Middle and Long Beach Breakwaters, provides the Ports of Los Angeles and Long Beach with wave protection for their infrastructure, navigation, berthing, and cargo operations. In addition, it protects the Cabrillo Shallow Water Habitat in the Port of Los Angeles Outer Harbor.

Built just over 100 years ago its design was developed based on experience of breakwater performance in similar environments.

= A Port at San Pedro Bay = San Pedro Bay is a hook-shaped bight oriented generally NW-SE, approximately 22 miles south of Los Angeles. Mendell (1891) described San Pedro Bay as bounded to the west by Point Fermin, the southernmost point of the Palos Verdes Peninsula, and to the east by Point Lasuen. These two points were named after the Jesuit priest Fermin Francisco de Lasuen by the British explorer George Vancouver in 1792. Due to the dynamic nature of the shoreline around Point Lasuen, this point disappeared over the years. Today, Point Lasuen would be located approximately at Newport Beach. Figure 1 shows San Pedro Bay as described by Morgan (1897).

Discovered in October 8, 1542, by Juan Rodriguez Cabrillo the Portuguese explorer sailing under the flag of Spain, the bay was first named "Bahia de los Fumos" (Bay of Smokes) after the smoke he saw rising from the nearby hillsides started by Indians to drive small game into the open (Los Angeles Harbor Department, 1983). In 1602, Sebastian Viscaino renamed the bay "Ensenada de San Andres" (Bay of Saint Andrew) mistakenly thinking he arrived on the feast day of Saint Andrew. In 1734, Cabrera Bueno discovered that Viscaino actually sailed into the bay on the feast day of Saint Peter, Archbishop of Alexandria and named the bay "Bahia de San Pedro" (San Pedro Bay). Additional information about the Port of Los Angeles can be found in Port of Los Angeles (2010a and 2010b).



In the northwest of the bay, in San Pedro, the site called Sepulveda Landing today the area between 14th and 16th Streets and, became an anchorage point for Spanish ships. In 1852, the German immigrant Augustus W. Timms acquired the Sepulveda Landing, which would later be known as Timms' Landing (or Timms' Point). Timms who would become a pioneer in the development of the harbor, built a wharf, added a warehouse, corral and other facilities to service shipping and the running of stages to Los Angeles (California Office of Historic Preservation, 2010 ; Big Orange Landmarks, 2008 ). Figure 2 shows a view of Timms' Landing from the south (California State Library, 2010).



In 1851, Phineas Banning arrived to San Pedro from Delaware. After a couple of years, he started a staging and freighting business. In the late 1850s, Banning and a group of investors purchased land north of San Pedro creating a landing and monopolizing the business in the bay. The site, originally named New San Pedro, was incorporated as Wilmington in 1863 after Banning's birthplace, and his facility became known as Banning's Landing. Figure 3 shows Banning's Landing in 1870 (Los Angeles Public Library, 2010).



Banning invested in the development of a more sophisticated port complex and in the creation of roads, telegraphs, and other connections to Los Angeles. In 1859, the first ocean-going vessel anchored in Wilmington harbor, and the 1860s saw the beginning of a small-scale maritime activity (Big Orange Landmarks, 2007 ; Wikipedia, 2010 ; and Megowan, 2010 ).

As the nation recovered from the Civil War, and with business booming, Banning led the crusade to solicit Congress for the first harbor improvements. The improvements commenced 1871 and were completed by 1873. The natural main channel, of less than 2 feet depth at the entrance to the harbor at mean low tide, was dredged to a depth of 16 feet in the interior channel and 14 feet at the entrance at mean low tide. In addition, two rubble mound jetties were built seaward: the east jetty from to Deadman's, and the west jetty from Timms Point seaward. In the early 1890s, the west jetty was extended seaward 800 feet to a total length of 3,450 feet, and the 6,600-foot east jetty was repaired (Casey, 1892). The port became a legal port of entry in 1874, complete with a customs house. Figure 4 shows the east and west jetties at San Pedro after the improvements in the early 1870s and early 1890s (Craighill,1892; and Walker, 1897).



Under the terms of the River and Harbor Act approved by the U.S. Congress on August 5, 1886, a preliminary examination of was conducted by Corps of Engineer’s Colonel G.H. Mendell (1886). Mendell justified a survey of and concluded that “….as an element of perhaps national importance, as it may be if Canadian Pacific route attracts commerce, the question appears to me to be deserving of careful examination and study, and I recommend the place as worthy of improvement.”

Following Mendell’s recommendation, Corps of Engineer’s Major Engineer W.H.H. Benyaurd (1888) performed a survey of with the purpose of establishing an outer breakwater for the protection of deep draft vessels. On the basis of his analysis of the local water depths, storm directions and the relative location of San Pedro’s anchorage area, Point Fermin, Catalina Island and San Juan Capistrano (today Dana Point), Benyaurd proposed a breakwater layout consisting of two breakwaters: a westerly breakwater extending 3,000 feet in a south 47 degrees east direction from the 3-fathom water depth off Point Fermin; and an easterly 2,500-foot breakwater running north 75 degrees east. The south-facing 1,000-foot opening was protected from the southerly seas by. This layout is generally referred to as the “1886 proposed breakwater” because it stemmed from the River and Harbor Act of August 5, 1886.

Under the terms of the River and Harbor Act approved by the U.S. Congress on September 19, 1890, a Board of Engineers was appointed to examine the Pacific coast between Point Dume and Capistrano with the purpose of determining the best location for a deep water port. The three-engineer Board evaluated Santa Monica Bay and San Pedro Bay and; on the basis of an analysis of hydrographic conditions, wave climate, wave exposure, cost of wave protection structures, and the ongoing shipping activities at Wilmington harbor; it concluded that San Pedro Bay was the best location for the deep water harbor (Mendell, 1891). The Board proposed a breakwater layout consisting of two breakwaters: a 2,400-foot long westerly breakwater extending from the shore at Point Fermin with a direction south 41 degrees east to the 6-fathom water depth; and an easterly 5,600-foot breakwater running north 75 degrees east on the 9.5-fathom water depth contour. This layout featured a west-facing 1,500-foot opening to afford entrance to the harbor from the west and provide for circulation of littoral currents. It was acknowledged that the location of this opening would produce some disturbance in the anchorage area, but not to any serious extent. This layout is generally referred to as the “1890 proposed breakwater.”

As the Senate Commerce Committee was considering an appropriation for harbor improvements at San Pedro, local business interests headed by Southern Pacific Railroad’s partner Collis Huntington and political interests led by Senators Jones and Frye started to weigh in and managed to kill the appropriation for San Pedro (Los Angeles Harbor Department, 1983). Huntington’s interest was in where Southern Pacific was building a wharf and owned land. Appointed by Corps of Engineers Special Orders No. 33 of July 27, 1892, a Board of Engineers made a careful and critical examination for a proposed deep water harbor at San Pedro or Santa Monica bays. The Board reported which was the most eligible location for such harbor in depth, width, and capacity to accommodate the largest ocean-going vessels and the commercial and naval necessities of the country, as required by the River and Harbor Act of July 13, 1892. The five-engineer Board concluded that, on the basis of future foreign trade growth prospects, the proposed deep water harbor was of high national importance and well worthy of construction by the Government, even at a large expense. In a report dated October 27, 1892, (Craighill, 1892) the Board unanimously selected as the most eligible location for the harbor. From a navigation perspective, and in order to maximize protected area, the Board concluded that a western entrance, as proposed in 1886 and 1890, was not necessary and therefore recommended a single 8,200-foot curved breakwater extending southward and eastward from Point Fermin. This “1892 proposed breakwater” consisted of a rubble mound substructure and a superstructure built of large rectangular-form stones. Craighill (1892) provides additional details about cross-section characteristics, methods of construction and relevant experience with the Delaware Breakwater which, at the time, was under construction.

Despite the fact that San Pedro had been selected as the best location for a deep water harbor in three occasions (1886, 1890 and 1892), Mr. Huntington and his political allies continued their opposition to San Pedro and managed to send a $3 million dollar appropriation for Santa Monica to the Senate floor in 1896. The prospects for a deep water harbor at San Pedro were fading. However, in two full days of testimony California Senator Stephen White managed to achieve an amendment to the River and Harbor Bill by which the appropriation would go to or San Pedro based on the decision of another Board of Engineers (Los Angeles Harbor Department, 1983). The decision of the majority of the Board was to be final.

Under the terms of the River and Harbor Act approved by the U.S. Congress on June 3, 1896, a Board of Engineers was appointed to locate a deep water harbor in or. The five-engineer board with Rear Admiral John Walker as chairman reported on March 1, 1897, its 4-to-1 decision in favor of San Pedro. The “1896 proposed breakwater”, like the “1892 proposed breakwater”, consisted of a rubble mound substructure supporting a superstructure composed of large rectangular-form stones. However, the single 8,500-foot breakwater was laid out detached from Point Fermin starting at approximately the 4-fathom (24 feet) water depth contour (Fries, 1912). It consisted of a western 3,000-foot long straight segment connected to a 3,700-foot long eastern straight segment by a 1,800-foot long 1,910-foot radius curved segment located in approximately 8 to 9 fathoms. The approximately 2,100-foot opening between the west end of the breakwater and the shoreline was provided to allow for the passage of current to prevent accumulation of sand in the harbor, fouling and, in good weather, provide a convenient entrance for light-draft coasting vessels (Walker, 1897). Figure 5 shows the four layouts developed for the San Pedro Breakwater since 1886 (Fries, 1907), and Figure 6 shows a rendering of the harbor as it looked after completion of the breakwater (Los Angeles Harbor Department, 1983).





= Design = The design of the San Pedro breakwater, consistent with the engineering practice at the time in the late 1800’s, was developed on the basis of experience of breakwater performance in similar marine environments and featured a substructure and a superstructure. For cost estimating purposes, Craighill (1892) developed a cross-section for the “1892 proposed breakwater” analyzing the Delaware Breakwater which, at the time, was under construction. Craighill (1892) analyzed 40 cross-sections of the completed work and 29 cross-sections of the uncompleted work at. He noted that the Delaware Breakwater was exposed to storms much more violent than those which occur in and, therefore, considered that the dimensions derived for the “1892 proposed breakwater” may be adopted with safety.

Similarly to Craighill (1892), the Board of Engineers headed by (1897) developed the layout and a cross-section for the San Pedro Breakwater on the basis of a general evaluation of the site, hydrographic conditions, exposure to storm waves, etc. Because no detailed analysis of the meteorological and oceanographic conditions are presented in their reports, the relatively primitive design methods and standards in the late 1800’s, and the similarities between the “1892 proposed breakwater” cross-section and that presented by Walker (1897) for the San Pedro Breakwater, it can be concluded that the cross-section adopted for the San Pedro Breakwater was derived on the basis of experience with the Delaware Breakwater and the general trends in breakwater design at the time. The following lists key characteristics, dimensions and provisions made for the San Pedro Breakwater, as defined by (1897) with minor edits:
 * The breakwater shall consist of a random stone substructure terminating at mean low water, and surmounted by a superstructure of more regularly shaped rock roughly placed and finishing 14 feet above mean low water, this being about 7 feet above extreme spring tides.
 * The superstructure shall be protected at each end by a block of concrete 40 feet square, finishing 20 feet above mean low water.
 * The substructure shall finish 38 feet wide at mean low water and 90 feet wide at the assumed approximate plane of rest, 12 feet below mean low water. The plane of rest is the horizontal plane below which the action of the sea is assumed to be so small that it may be neglected (Craighill, 1892).
 * The substructure shall have a slope of 1.3 horizontal to 1 vertical for the whole height on the harbor side, and below the assumed plane of rest on the ocean side. This slope is the slope that random stone dumped in water is expected to assume (Walker, 1897).
 * For the 12 feet above the plane of rest on the ocean side, the slope shall be 3 horizontal to 1 vertical, affording a flatter slope for the waves to break upon (Walker, 1897).
 * At the breakwater ends, the substructure shall finish square, with a slope of 1.3 horizontal to 1 vertical, corresponding to that on the harbor side.
 * The superstructure shall be 38 feet wide at the base at mean low water and 20 feet wide at the top.
 * The superstructure shall be formed of heavy stones of approximately rectangular shape, these stones being laid with their greatest dimensions at right angles to the breakwater and in the form of rough steps, the retreat of these steps being 10 feet on the ocean side and 8 feet on the harbor side.
 * To protect the work from damage from waves passing around the ends, a single block of concrete 40 feet square and 20 feet high shall substitute the ordinary superstructure at each end, this block of concrete forming a monolith of 32,000 cubic feet, weighing 2,000 long tons (1 long ton = 2,240 lbs).
 * For the substructure, the stone to be used must weigh at least 130 lbs/ft3. No stone shall weigh less than 100 pounds; not less than two-thirds of the total amount by weight contained in each load deposited must consist of stones weighing at least 1,000 pounds each; and not less than one-third of the total amount by weight contained in each load deposited must consist of stones weighing at least 4,000 pounds each. The stones shall be of rough, irregular shape, in the form in which they come from the quarry; the least dimension shall not be less than one quarter the greatest dimension.
 * For the superstructure, the stone to be used must weigh at least 160 lbs/ft3. The stones used in constructing the wall on the sea side must weigh not less than 16,000 pounds each. The stones used in the wall on the harbor side must weigh not less than 6,000 pounds each. The stones in both walls must be roughly rectangular in shape (blocks), so as to form a reasonably compact structure, with rough steps. The stones used for filling between the walls must be of the same quality (no size specified). All openings in the top surface must be filled.
 * Each end of the superstructure shall be formed of a single block of concrete 40 feet square and 20 feet high; the center of this block is to be on the established center line of the breakwater, and the bottom of the block is to be 3 feet below and the top 17 feet above the plane of mean low water. The concrete shall be formed of broken stone, sand, and Portland cement, in the proportions of six parts of stone, three parts of sand and one of cement by volume. A wooden mold shall be constructed on the substructure, in which the concrete block shall be made; this mold shall consist of sides only; the stone of the substructure shall be covered with gunny cloth or other suitable textile material loosely placed, and form the bottom. The construction of each block shall proceed continuously, without interruption, until the whole mass is placed. The engineer officer in charge may authorize the substitution of gravel in place of broken stone and sand, and may prescribe such rules as he may deem advisable for the inspection and manipulation of the materials used in the concrete, and may increase proportion of cement in work under water.
 * The total length of the breakwater at the mean low water shall be about 8,500 feet, but this length may be increased, if found practicable without exceeding an aggregate cost of $2,900,000.
 * The single detached breakwater shall consist of a western 3,000-foot long straight segment connected to a 3,700-foot long eastern straight segment by a 1,800-foot long 1,910-foot radius curved segment located in approximately 8 fathoms. The approximately 2,100-foot opening between the west end of the breakwater and the shoreline is provided to allow the passage of current to prevent accumulation of sand in the harbor, fouling and, in good weather, provide a convenient entrance for light-draft coasting vessels.
 * The breakwater will have 85 stations, each 100 feet apart, with station 0 at the west end of the breakwater and station 85 at the east end.
 * The depth at mean low water along the site of the work varies from 24 to 52 feet.
 * Six pre-construction borings along the breakwater alignment showed, in general, gravel or hard clay within 6 feet from the surface leading to assume that the foundation for the breakwater was excellent. However, bottom conditions on the eastern end were softer leading to conclude that some settlement may take place at this end, but not for a distance exceeding 1,000 feet, and averaging about 5 feet. A provision was made by which no portion of the superstructure would be erected until the substructure on which it would be placed had been completed for at least six months, and any settlement had be corrected by leveling up the substructure before beginning work on the superstructure.

The cross-section specified by Walker (1897) is reproduced in Figure 7 with minor edits and including principal dimensions and stone characteristics. Figure 8 shows the specified layout and bathymetry (Walker, 1897). For additional details see Walker (1897).





= Construction = The San Pedro Breakwater was constructed under three separate contracts. Initially, the planned detached breakwater was built under the first two contracts; and the connection to the mainland, to achieve the current layout of the breakwater, under the third one.

The first contract was awarded on August 12, 1898, to Heldmaier and Neu of Chicago, Illinois (USACE, 1985a) who planned on bringing the stone for construction from Catalina Island, likely because of the positive assessment made by Walker (1897) about the quality and quantities of stone at the Los Angeles City Quarry in the island, and the recommendation from Craighill (1892) for construction from barges rather than from a trestle. Buoys were anchored at intervals along the centerline of the breakwater and on April 26, 1899, the first barge of stone from Catalina Island made fast to a buoy and dumped its cargo. Figure 9 shows the typical barge used, which dumped stones over the side by filling air chambers and inducing a heel angle.



Construction progressed well for a while, and soon about 80,000 long tons (1 long ton = 2,240 lbs) had been deposited (Bowers, 1907). Then, the contractor was unable to produce stone as fast as planned and on the account of unsatisfactory progress the contract was annulled on March 19, 1900. At that time, Heldmaier and Neu had placed 84,581 long tons of stone, partially completing the substructure to station 21+00 (USACE, 1985a).

On June 7, 1900, a contract for completing the breakwater was entered into with the California Construction Company of San Francisco and work was resumed on August 4, 1900. The new contractor elected to build a double track standard gauge railway trestle along the centerline of the breakwater and bring stone by rail from quarries at Chatsworth Park, 60 miles from the site in Los Angeles County; Declez in and in San Bernardino County and Casablanca in Riverside County, 80 and 100 miles away, respectively (McKinstry 1904 and Aubury, 1906). The trestle support frames (bents) were about 16 feet apart, center-to-center, and each containing four perpendicular and two batter piles. A large pile driver worked installing the bents and extending the trestle, ahead of two large cranes that travelled the trestle placing the large stones. The approximately 30-ton hoisting capacity cranes were 90-hp converted Barnhart steam shovels, with specially rigged booms and hoisting tackle that substituted the shovels. These cranes were prevented from tipping over when the boom was nearly at right angles to the car by steel guys fastened to the opposite track. In addition, very heavy brackets carrying two rollers were fitted to each side of the front of the crane. The rollers rested on a movable 4-foot platform of 12-inch timbers supported on other 12-inch timbers placed on top of the caps of each bent between tracks. Figure 10 shows the breakwater under construction, trestle, pile driver in the foreground, and loaded cars and crane in the background.



At the quarries, the stone was loaded on standard flat cars which were hauled directly out onto the trestle at San Pedro. Here, the smaller stones, up to about a ton, were barred off the flat cars near the centerline of the breakwater, while the heavy stones were swung out by the cranes over the water and deposited on the sides of the structure. When the boom was in the desired position, the stone was released by means of a trip chain worked from the engine room. Thus, while the upper central portion was composed of all sizes over 100 lbs mixed, the lower central portion consisted mostly of small stone, and the two sides contained only heavy stone. Such segregation was not required by the specifications except for the upper portion of the sea slope, but it was the result of the contractor's method of construction, which conduced to an economy by increasing the voids. From the tonnage and specific gravity of the stone, and carefully sounded cross-sections, the percentage of voids was computed to be 37% (McKinstry, 1904). Figure 11 shows a crane dropping a stone, loaded cars and workers alongside.



Bowers (1907) and Fries (1912) provide descriptions of how the superstructure was built. The regular shaped blocks used in the superstructure were carefully placed and fitted. A section of the top of the substructure was first brought carefully to the required level (mean low water elevation), and then a large block weighing from 8 to 25 tons was lowered into place. The stone was first placed in its approximate position to see how it fitted. If it did not rest quite level or a bit too high or low, it was raised again, and the smaller stones of its bed were rearranged. The large superstructure blocks were therefore placed three or four times before left in their final position. The specifications required the stone in the substructure to be dumped and brought up to a little above low water at least six months before any superstructure stone was placed, to allow for the substructure to adjust itself to any settlement that might occur. This left a very irregular foundation on which to place the stone blocks, and in order to get the bottom stones approximately level it was often necessary to pull out large stones from the substructure. The resulting holes were filled with smaller stones up to the level of low water. The elevation of a stringer along the trestle was used as a datum plane and, by means of a measuring pole lowered from above as each stone was placed, the upper surface of a layer was kept level and regular. The stones of the bottom layer on the sea side could be placed only during calm weather at low tide. In building the superstructure, much of the piling was sawed off just above low water, and the railroad tracks blocked up by these pieces of piling which were further shortened from time to time as the superstructure gained in height. This was for the purpose of making the density of the superstructure as great as possible by replacing with granite the space occupied by the piling. Sandstone was placed in the lower and inner portions of the substructure, while granite stones were placed on the outside slopes, and blocks on the superstructure. Figure 12 shows a view of the superstructure granite blocks on the harbor side.



According to Fries (1912), the original design of the breakwater was faulty in one very important aspect. The slopes on the harbor side and below the plane of rest, 12 feet below low water on the seaward side, were assumed at 1 vertical on 1.3 horizontal, while the slope on the seaward side from low water to the plane of rest was 1 in 3. No berm was provided for either side, the width of the rubble mound at low water being 38 feet or the same as the width of the bottom of the superstructure. However, even before any considerable construction work was done, it was deemed advisable to provide a berm not less than 4 feet wide on the harbor side to protect the inner wall from being undermined by the masses of water that, experience with breakwaters on the Great Lakes and elsewhere, had shown would be dashed over during very severe storms. No berm was placed on the seaward side until a section of the superstructure had been in place long enough to show that some of the stones in the bottom layer on the seaward side would be undermined by the back wash of the waves unless a berm were provided. While it was not thought that this would in any way affect the stability of the breakwater, yet if the symmetry of the work was to be maintained, a berm was necessary. Accordingly, for all extensions of the breakwater thereafter, as well as for those portions of the substructure already completed, sufficient stone was deposited on the seaward side to make a berm approximately 5 feet wide. In addition, several thousand tons were deposited along the bottom layer on the seaward side of the superstructure, where the latter was already partially or wholly completed. This work was expensive and difficult to execute; it being necessary, as a rule, to roll stone off cars by crowbars or similar means.

McKinstry (1905) reported that the substructure was completed at the beginning of the fiscal year to a length of 7,284 feet, and by the end of the fiscal year ending June 30, 1905, for a length of approximately 8,212 feet and to the mean lower low water; with some stone deposited in the remaining 288 feet. It is important to note his “mean lower low water” remark, since until his report previous drawings and references indicated that the substructure was to be built to a “mean low water” elevation. This is an important piece of information for the analysis of the settlement of the breakwater. Work on the superstructure began in October 1902 commencing 628 feet from the west end of the breakwater. By 1905 a length of 2,880 feet was built (McKinstry,1905) and by June 30, 1908, the superstructure was partially completed over a length of approximately 8,403 feet (Chief of Engineers, 1908).

McKinstry (1905) further noted that, as work progressed, it became evident that a breakwater longer than 8,500 feet could be built for the authorized $2,900,000. On January 11, 1905, authorization to extend the breakwater to a total length of at least 9,000 feet was obtained. In 1908, the Chief of Engineers (1908) reported the decision to build the breakwater to a total length of 9,250 feet, 750 feet longer than originally planned. The contract work was completed on September 9, 1910.

According to USACE (1996), due to a fire in 1942 all formal breakwater design parameters normally associated with breakwater design were lost. Therefore, the best representation of the breakwater final configuration would be based on the descriptions given above, and surveys and investigations performed after the completion of the works. Figure 13 shows a plan view schematic and stations of the 9,250-foot long breakwater. For practical purposes, it can be assumed that the western segment extends from station 0+00 to 30+00, the curved segment from station 30+00 to 48+00 and the eastern segment from station 48+00 to 92+00. Figure 14 shows the breakwater cross-section depicted in Aubury (1906), as provided by Corps of Engineers Captain C.H. McKinstry. Figure 15 shows a comparison between the 1906 cross-section template, shown in Figure 14, and cross-sections corresponding to stations 51+00 to 90+00 on the eastern segment of the breakwater (repaired stations omitted) obtained in the August 2009 survey performed as part of the assessment presented in this report. It can be observed that the general shape of the 1906 template appears to have been achieved, however, the structure has settled on average approximately 2 feet (the height of one harbor side granite block).







At the time of the approval of the breakwater construction project in 1896 there were no plans for the development of docking facilities in the outer harbor except near the entrance to the inner harbor. Since then, the idea of an outer harbor developed. By 1907, work began in an area of the shore behind the breakwater to be bulkheaded and reclaimed as part of a commercial development (Fries, 1907). Authorized by the River and Harbor Act of March 2, 1907, Fries (1907) performed an examination with the purpose of determining if the breakwater should be extended to the shore, closing the planned opening. He recommended to extend the breakwater to the shore on the basis that: a) the waves coming through the opening during stormy weather would make it difficult and perhaps hazardous for vessels to lie at wharves in the outer harbor, b) that considerable silt would enter the harbor through the opening and c) that little or no shipping would use the opening in the future, especially during storms. The shoreward extension of the breakwater was authorized by the River and Harbor Act of June 25, 1910. In view of this project, the large monolith concrete block proposed for the shore end was decided to be unnecessary and it was never built. Figure 16 shows the eastward end 40-foot square by 20 feet concrete block and the Angel’s Gate Lighthouse which was completed in 1913.



On January 4, 1911, a contract to extend the breakwater to the shore was entered into with the W.S. Russell Company of Los Angeles. On April 21, 1911, construction began and the project was completed on December 20, 1912, (Chief of Engineers, 1911 and USACE, 1996). According to the Chief of Engineers (1911), the estimated 1,887-foot long extension was to be built of random rubble stone to a height of 15 feet above mean lower low water with a top width of 15 feet and slopes of 1 vertical to 1.5 horizontal on the seaward side, and 1 vertical to 1.3 horizontal on the harbor side. Fries (1907) noted that the extension would began from a point on the 24-foot contour distant approximately 1,850 feet from the high water line on the shore; and that the proposed stone could vary in weight from 50 lbs to 15 tons, the largest being placed on top and on the ocean side down to about 15 feet below mean lower low water. USACE (1985a) notes that granodiorite stone from the Declez quarry was used.

Similarly to McKinstry (1905) and Fries (1907), the Chief of Engineers (1911) referred to the mean lower low water as the project vertical datum. Figure 3‑17 shows a theoretical and surveyed cross-section of the breakwater at station 0+00, adapted from USACE (1912) Drawing No. 1319 with minor edits. It is noted that the plan appeared to be to build a symmetric structure, and that the as-built elevation of the crest was 14 feet above MLLW, which is 1 foot less than proposed by the Fries (1907) and the Chief of Engineers (1911). Inspection of USACE (1912) Drawing No. 1319 also showed that the as-built crest was wider than the planned 15-foot width, and that the slope on the seaward side was variable and in the 1V:1.5 to 2H range. The drawing noted that the survey was performed on November 12-13, 1912, and that the datum was the MLLW. The extension featured 20 stations starting at station 0 at the west end of the breakwater, and progressing westward every 100 feet to station 18+00, the last station being station 18+60.

Figure

Figure 3‑18 shows a view from the shore of the shoreward breakwater extension after completion in the 1920s (McKinzie, 2005). The original west end of the breakwater is at the first bend from the shore.

Figure

Table 1 summarizes key dates and events in the design and construction of the breakwater.

= Stone Sources and Characteristics = The first examination of stone characteristics from the various sources of stone available for the construction of the breakwater was performed by Dr. George P. Merrill curator of the department of geology in the. In the report submitted by (1897), he notes the following:
 * The material classed as granites from the Casablanca and Declez quarries are rocks of an intermediate type between the true granites and the diorites and which have been classed as granodiorites by geologists working in these regions. They consist essentially of quartz, both potash and soda-lime feldspars, hornblende, and black mica. The structure is essentially that of the granites proper. So far, as it can be determined from the samples submitted, they contain no constituents such as will render them liable to more rapid degeneration than is characteristic of rocks of this group and structure.
 * The so-called Catalina porphyry is a volcanic rock, a lava of comparatively recent geological age and is to be classified as rhyolite. There are available only theoretical data for estimating the suitability of rocks of this type for general structural purposes. They are a trifle more absorptive than the granodiorites, but contain no constituents liable to rapid decomposition. Stones of this type have thus far been too little used to give us any practical illustrations of their enduring qualities.
 * The sandstones (Chatsworth Park quarry, see Table 2) are composed essentially of angular granules of quartz and siliceous minerals cemented quite largely by calcite. This cementing constituent, aside from possessing little strength of its own, is liable to removal by solution, causing the stone to disintegrate.

Table 2 shows the results of the examinations of the stones specimens provided at the time. Details about how the stone tests were performed are provided by Langley (1897).

Langley (1897) noted that there was not sufficient time for other tests, nor they had proper facilities for performing them; but from the facts given coupled with experience, he was led to conclude that the sandstone would be liable to serious disintegration on exposure. The Catalina porphyry would be preferable, and would very probably meet all the requirements. The best of the samples submitted were those from the quarry and then those from the Declez quarry.

Following the initial examination by Dr. Merrill, several other stone examinations were performed which are summarized in USACE (1985a) and USACE (1996), and included here with minor edits.

Stone placed by Heldmaier and Neu under the first contract for construction was andesitic rhyolite from the quarry, near the Isthmus, in. As stated previously, only a small portion of the substructure (to approximately station 20+00; USACE, 1985a) was completed with stone from this source prior to annulment of the contract, largely due to very slow production at the quarry.

Under the second contract, California Construction Company utilized four different quarries: Originally, the sandstone was used in the substructure interior along with Declez granodiorite, while the outer 10 feet of the substructure were constructed of Declez granodiorite only.
 * 1) Casblanca (granodiorite)
 * 2) Chatsworth Park (sandstone), and
 * 3) Declez (granodiorite)
 * 4) Bly (tonalite)

In 1906, however, use of the quarry was halted due to uncertainty concerning the long-term effects of seawater on the calcite matrix of the sandstone. It is noted that originally Dr. Merrill raised concern about the sandstone from this quarry in the (1897) report. Mr. David Hughes, who designed the breakwater and chose the stone from the various quarries, felt that the sandstone was adequate, and that the calcareous cement would not dissolve. However, he conceded the point and stopped using stone from that quarry. Consequently, the substructure was built entirely of Declez granodiorite from about station 85+00 to the east end. During the construction of the breakwater, Mr. Hughes had a cubic foot of sandstone placed underwater near the breakwater. Periodically, until the mid l930s, the sandstone block would be raised and examined. The stone remained sound at each inspection. The cementing material was never dissolved by sea water as Mr. Hughes had predicted (Hughes, 1897-1942).

Of the 1,967,204 long tons of stone placed in the substructure by the California Construction Company between stations 15+00 and 85+00, 524,072 long tons were sandstone. The stone used to build what are generally referred to as the granite blocks in the superstructure (or dimension stone) is granodiorite from the and tonalite from the Bly quarries. Although available Government records do not mention the Bly quarry, correspondence between California Construction Company and the U.S. Engineer Office refer to dimension stone (granite blocks) delivered from Bly in February 1909. The stone used to fill the gaps and the core of the superstructure (the core stone) is both and Declez granodiorites, possibly with some Bly tonalite. The berm on the seaward side, which was added during construction, was built entirely of Declez granodiorite. The shoreward extension of the breakwater was also constructed of granodiorite from the Declez quarry.

Table 3 lists the stone sources and characteristics of the stone used for construction of the breakwater, including the shoreward extension (USACE, 1985a).

On the basis of the information presented above, idealized stone type distributions were developed. Adapted from USACE (1985a), Figure 19 and Figure 20 show an idealized profile and a cross-section (station 60+00) of the breakwater at the time the breakwater was completed in 1912, including stone type distribution. Symbols are listed in Table 3. This idealization assumes that:
 * during construction and according to the specifications, the superstructure was placed on the substructure after the substructure had been completed for six months, leveled, and any settlement was corrected to achieve the design elevation of 14 feet MLLW, and
 * the bottom of the breakwater was located in agreement with the borings performed during the Condition Survey of 1984 (USACE, 1985a).





= References =