IAO STREAM FLOOD CONTROL, MAUI

(See p. 36 for project drawing.)

Iao Stream, which originates in Iao Valley on the island of Maui, flows a distance of 8 miles through the town of Wailuku to the Pacific Ocean. The stream drains a basin of approximately 10 square miles. The slope of the drainage basin is approximately 1,800 feet per mile in the headwater area, flattening to about 120 feet per mile near the mouth of the stream. The mean annual precipitation for this drainage basin ranges from about 400 inches at the summit to about 25 inches near the coast, making this basin one of the wettest spots in the State. Approximately 27 percent of the population of Wailuki, which had an estimated population of 7,600 in 1965, reside in the flood plain. The principal industry in the flood plain is sugarcane production and processing.

The Iao Stream flood control project was authorized by the Flood Control Act of 1968. A favorable survey report which was submitted to higher authority on April 5, 1966 has been published as House Document 151–90–1. This project document provides for partial protection of the lower 3 miles of Iao Stream. The plan of improvement includes approximately 2 miles of channel improvement from the Market Street Bridge to the ocean and a debris basin approximately 3 miles upstream from the mouth of the stream. The 2 miles of channel improvement consist of paved inverts in various reaches of the stream, realinement of portions of the stream, channel widening and deepening with bottom width varying from 60 feet at the downstream side of Market Street Bridge to 175 feet near the mouth of the stream, reinforced concrete vertical walls under the Wailuku Sugar Co. bridge, increased heights of portions of existing banks, and low levees along sections of both banks.

Funds for advanced engineering and design have not been appropriated.

HAWAII

KAWAIHAE HARBOR

(See p. 37 for project drawing.)

Kawaihae Harbor lies at the north end of Kawaihae Bay on the northwest coast of the island of Hawaii. The existing harbor was created by dredging part of an extensive coral reef which extends seaward 4,000 feet and runs along the shore more than a mile to the south of Kawaihae. The harbor is protected from northeastern and southern storms by the Kohala Mountains and the promontory at the south end of the bay. However, the harbor is exposed to storm waves generated from the northwest, west, and southwest.

Winds from the northwest to southwest sector dominate at Kawaihae and are highly unpredictable. In addition, the harbor is affected by squalls which occasionally sweep down the mountainside and make vessel handling in the entrance channel difficult. Ships may suddenly be set off course and out of the center of the channel before the helmsman can make the required steering adjustments. Adverse winds and surge have often caused delays in docking operations and, in some instances, have frustrated vessel calls and caused diversion of ships to Hilo Harbor.

Kawaihae Harbor, the second largest harbor on the island of Hawaii, serves an area from Milolii on the southwest coast to Honokaa on the northeast coast of the island. This area includes all of the Kona coffee-producing land, the majority of the island's cattle ranches, the Kamuela agricultural area, and approximately one-third of the northeast coast sugar-producing land. The harbor now

serves both transpacific and interisland traffic, but transpacific service is limited to bulk cargo Twice weekly, interisland barge service is augmented by irregular calls by chartered barges. Transpacific vessels now calling at Kawaihae Harbor are primarily C-3-class freighters and T-2 tankers. The Californian and the Hawaiian, both 633-foot freighters, each called once, but they were then removed from Kawaihae Harbor because navigation into the harbor was considered too hazardous. The proposed harbor modifications will open it to vessels of the jumboized C-4 and modified T-2-class vessels, and shipping interests have indicated that they will begin use of these larger vessels as soon as the harbor will safely accommodate them.

There are two recommended plans of improvement: (1) A modification of the existing deep-draft harbor; and (2) the small boat harbor. The plan of improvement for the deep-draft harbor calls for the following modification of the existing Federal project: the widening of the seaward 1,450 feet of the entrance channel along its northerly side by 100 to 120 feet; widening the seaward side of the harbor basin by a maximum of 200 feet to create an additional maneuvering area of about 9.5 acres; lengthening the harbor basin on its south side by a maximum of 500 feet to create an additional maneuvering area of about 8.5 acres; and planting and landscaping the spoil area.

The second plan of improvement concerns itself with a small boat harbor. This plan would entail Federal dredging of a main access channel and construction of a protective wave absorber and mole. The rubble wave absorber, about 1,075 feet long, would parallel much of the existing fill revetment which forms the south shoreline of the deep-draft harbor. A sheltered water area of about 10 acres would thereby be formed between the wave absorber and the shore revetment; this area would be dredged to create the new basin. The main access channel would be 900 feet long, 80 to 100 feet wide, with an outer depth of 10 feet and an inner depth of 8 feet.

The proposed harbor improvements were model tested at W.E.S. and the general design memorandum was approved by OCE in June 1968. In September, the State requested that the small boat harbor be relocated outside the deep-draft basin. This will necessitate additional design studies.

HONOKAHAU HARBOR

(See p. 38 for project drawing.)

Honokahau Harbor will be located in the Kona coast resort region on the west coast of the island of Hawaii approximately 28 nautical miles southwest of the Federal deep-draft harbor at Kawaihae and 2 miles northwest of the Kona Airport at Kailua. This region is characterized by its pleasant climate and outstanding natural beauty which, together with a number of historical sites and excellent coastal and deep-sea fishing grounds, make Kona a popular sportsfishing and tourist center. An estimated 185,000 tourists visited the island of Hawaii in 1966 and most of these stopped in Kailua.

Due to the influence on the normal trade wind pattern caused by the mountain peaks of Mauna Loa and Mauna Kea (each almost 14,000 feet high), southwesterly winds predominate; however, westerly and southerly winds do frequently occur. Wind velocities over 24 miles per hour are recorded two or three times each year, usually in the winter months. These winds sometimes reach gale force. At present there are no ports of refuge south of Kawaihae to provide shelter for small craft during storm periods. The proposed harbor at Honokahau would provide this shelter in addition to the normal function of being a base of operations for local fishing and recreational boats, and an attractive stopping point or cruise destination.

In 1962 the State of Hawaii planned to construct Honokahau Harbor without Federal aid, but when engineering studies showed construction costs substantially greater than anticipated, the State sought Federal assistance. The Honokahau Harbor was then studied under the survey authority for the "Coasts of the Hawaiian Islands" and was authorized under the River and Harbor Act of 1965, House Document 68, 89th Congress, first session.

Various plans of improvement for this harbor were model tested in Honolulu, Hawaii. Model testing of the selected plan of improvement was completed after submission of the survey report. The plan of improvement presented in the general design memorandum provides for a protected harbor basin of 14.5 acres to accommodate about 450 boats. The design memorandum was approved by OCE in March 1968. During the preparation of plans and specifications for

the project, the dimensions of the harbor were modified to provide for an entrance channel 965 feet long, 120 and 160 feet wide with a depth of 20 and 15 feet; a main access channel 782 feet long, 120 feet wide with a depth of 15 and 12 feet; and wave absorbers with combined lengths of 500 feet along both sides of the entrance channel and a 285-foot wave trap at the shoreward end of the entrance channel.

In June 1968, a construction contract was awarded to Stewart-Pacific in the amount of $1,988,974.33 for the authorized Federal project and portions of the State berthing area. The total Federal cost is $808,068. Construction is proceeding on schedule.

The inspection party visited this project on November 20, 1968. The resident engineer, Capt. Leonard Hasse, Jr., of the Honolulu district, briefed the party, explaining the various work items that were in progress.

KAIMU BLACK SANDS BEACH

(See p. 39 for project drawing.)

Kaimu Black Sands Beach has a seasonal ebb and flow of sand deposits, and a permanent erosion in the width of the beach. The width of the beach has decreased approximately 400 feet in 60 years, or 6.5 feet per year. In 1966 the county of Hawaii requested a study of the Kaimu Beach erosion under the small projects authority of the River and Harbor Act of 1962.

This beach lies along the southeast coast of the island of Hawaii, just northeast of the village of Kalapana, and is popularly known as Kalapana Beach. Kaimu Black Sands Beach, about 1,000 feet long, varies in width from 70 feet during late winter to 118 feet in early fall. The sand is composed almost entirely of volcanic glass and lava fragments (glass predominating) which gives the sand its famed black color. The sand is only moderately well sorted and is very coarse in size, with some gravel-size components. Erosion of the beach during winter exposes an underlying boulder layer at the northeast end of the beach. The back shore is black sand within a coconut grove which, farther inland, terminates against basaltic rock. This lava also forms projecting points at either end of the beach. Offshore, the bottom is predominantly rock. Waves are generally rather large, as can be seen by the steep foreslope, and a strong rip current periodically flows off the southwest end of the beach.

Kaimu is the most publicized, and has the easiest access from Hilo, of all of the small black sand beaches. Future plans for this area are based on expansion of recreation facilities coupled with creation of a low-density resort complex. With the completion of the Puna Coast Highway and the Chain of Craters Road, Kalapana-Kaimu will become the gateway to the Hawaii Volcanoes National Park.

A reconnaissance report indicated the need for further study. A detailed project study is scheduled to be completed in 1969.

HILO HARBOR TSUNAMI AND NAVIGATION PROJECTS

(See p. 40 for project drawing.)

Hilo Harbor, second largest seaport in the State, is on the northeast coast of the island of Hawaii. The harbor facilities have made the city of Hilo which is adjacent to the harbor the center of economic activity for the entire island.

The existing harbor was constructed in 1930 and consists of a rubblemound breakwater 10,080 feet long, an entrance channel 35 feet deep, and a harbor basin 1,400 feet wide, 2,300 feet long and 35 feet deep. Modifications to this harbor were authorized by the River and Harbor Acts of 1907, 1912, 1925, 1960, and 1962.

The harbor modification project authorized by the River and Harbor Act of 1960 intended to provide protection from tsunamis and to improve navigation conditions in the harbor. The initial plan of improvement proposed to strengthen and raise the existing breakwater, to extend the breakwater to a total length of 10,570 feet, and to construct a 4,000-foot west breakwater and a 6,600-foot land dike. Hydraulic model studies of this plan and other alternative plans have been completed and the report of these model studies published. Further work on this project has been deferred indefinitely because the State of Hawaii is unwilling to provide firm assurances of cooperation.

A Hilo Harbor modification study was authorized by House Resolution No. 739 of May 9, 1967, to determine the feasibility of harbor modifications, particularly enlargement and surge reduction. Currently, the University of Hawaii, under contract to the Honolulu Engineer District, is conducting a gaging program in Hilo Harbor. This program, presently estimated to be complete in 1 year, should produce data which will permit analysis of the surge problem and model testing of the various engineering solutions to this problem.

In order to assure continued beneficial use of Hilo Harbor for commercial navigation during the studies for the surge problem and harbor modification, the Chief of Engineers authorized the emergency repair of the breakwater. This work was completed on July 22, 1968, under a contract administered by the Honolulu Engineer District.

This project was inspected and reviewed on November 20-21. Discussions were held with various individuals in an attempt to determine the reason for delay in proceeding with construction of the authorized breakwaters. It was learned that the principal reason for delay was the inability of the State of Hawaii to meet the large cash contribution required by the authorizing legislation. In order to determine the equity of the conditions of local cooperation it is recommended elsewhere in this report that the Secretary of the Army determine any adjustment of the cash contribution required of local interests as authorized by the River and Harbor Act of 1962.