Maintenance of Waterfront Facilities

The atmospheric, splash, and tidal zones of concrete piles can be inspected better from a skiff than from the edge of a deck. The submerged and mud zones where exposed should be examined by a diver or, where available and appropriate, an underwater television camera. Both piling and pile caps should be inspected for cracks, spalls especially in the tidal zone and along edges , disintegration, broken members, exposed reinforcing steel, and rust staining.

Decks should be similarly checked, especially along the bottom edges. The general condition of all surfaces, especially wearing surfaces, and expansion joints should be noted. Graving doc ks should be inspected as described in Appendix B 3. A reliable method of determining the condition of subsurface concrete is to extract diamond-drilled concrete cores that can be laboratory tested. Such specimens are usually obtained to 1 determine composition or the cause of the problem, 2 determine the depth or extent of deterioration, 3 determine appropriate methods of repair, and 4 establish legal responsibility for the failure.

For structural elements that are not massive e. The bottom inch of a deck should not be cored because the core could be lost by dropping out of the drill barrel; also, the core hole can be patched more readily. For massive sections e. Another mechanical method of inspection uses a concrete test hammer, a portable, manually operated instrument for nondestructive testing of hardened concrete.

This instrument measures the hardness or compressive strength of concrete by rebound of a steel plunger in a tubular frame. The hammer should be used only on surfaces where the concrete was cast against a form. Roughfloated or trowel-finished concrete surfaces will produce readings that do not truly indicate the quality of concrete. Readings vary with the age and moisture state of the concrete. Personnel using a test hammer should be well-trained in its proper operation and calibration.

Sonic and ultrasonic methods of inspecting hardened concrete measure the velocities of high frequency waves passing through a structural element. The sonic tester can be used on concrete as thick as 75 feet, while the ultrasonic instrument is limited to thicknesses less than 7 feet. Since sonic pulses do not traverse voids or air-filled cracks, these instruments can be used in detecting and evaluating imperfections and progressive deterioration. Another method is the use of a standard reference cell and a high-impedance voltmeter.

One lead is grounded to the reinforcing steel and the other is connected to the reference cell. The reference cell is touched to numerous locations on the concrete surface. This method can detect corrosion of reinforcing steel when there is no visual evidence of concrete cracking or distress.

TM 5-622 Maintenance of Waterfront Facilities

Steel can be located by means of magnetic devices, such as a Pachometer. Before planning a repair job it is essential to determine the cause of the problem: For proper repair of concrete structures all defective concrete must be removed, the concrete carefully replaced in accordance with an approved procedure, and effective drainage where needed provided. Concrete that is stressed under loads must be supported properly before the defective portions are cut away. In the repair of piles that are small in cross section, if the removal of defective concrete could be detrimental to the stability of the structures, an attempt should be made to relieve part of its load.

Where possible, joints should be avoided between low and high tide levels. Patches should not be carried across active cracks or joints. Concrete used in repairs must be protected and cured more carefully than usual. The old concrete could absorb moisture too rapidly from the new concrete, or the temperature of the old concrete could be too low to permit early development of strength of a concrete patch.

The volume-change characteristics of the new concrete should correspond to those of the old to avoid differential movements that will weaken the bond. The dry-pack method should be used for 1 filling narrow slots that have been cut during the repair of dormant cracks, and 2 filling holes with a cross-sectional area not greater than 36 square inches and a depth equal to or greater than the least surface dimension. The dry-pack method should not be used for filling 1 shallow depressions less than 1 inch where lateral restraint cannot be obtained, 2 behind exposed reinforcing bars, or 3 holes that extend th rough a bea m or bulkhead.

Regardless of depth, each hole or slot must be scrupulously clean, free of loose or cracked aggregate, and dry for at least 2 days before filling. The cleaned interior surface is coated with a stiff bonding grout, immediately followed by the dry-pack mixture.

The mix proportions for the bonding grout are 1 part of Type II portland cement to 1 part of fine sand previously washed and dried , with only enough freshwater to produce a consistency like that of thick cream. The mortar patch is usually darker than the surrounding concrete unless special precautions are taken to match the colors. Where uniform color is important, white cement can be used in sufficient amount as determined by trial to produce the desired lighter color. Sawtooth bit used to cut a slot for dry- packing. The surface of each layer should be scratched to facilitate bonding with the next layer.

1. ?
2. Computational Methods for Process Simulation;
3. Gender Swap Office Revenge (Gender Transformation Erotica).
4. How to Start a Cake Decorating Business at Home - UK.
5. Full text of "MAINTENANCE OF WATERFRONT FACILITIES".
6. Account Options;
7. The Single Fathers Guide To Life, Cooking and Baseball;

One layer can follow another immediately unless appreciable rubberiness develops, in which event the repair should be delayed 30 to 40 minutes. Alternate layers of wet and dry materials should not be used, and the holes should not be overfilled. Each layer should be fully compacted over its entire surface by using a hardwood stick and a hammer. A few light strokes with a cloth sometime later may improve the appearance. Neither steel finishing tools nor water should be used to facilitate finishing; otherwise, an ugly patch will result.

The cast-in-place method of restoring concrete should be used when: All remaining concrete of questionable quality should be removed. Replacement of deteriorated concrete should be delayed several days until the soundness of the excavated surfaces and remaining concrete can be confirmed. Air-driven chipping hammers are most satisfactory for removing the concrete, although good work can be done by hand methods. A gad is better than a chisel because it leaves a rougher, more natural texture for bonding.

The square-cut edges required for many repairs can be sharply and neatly cut with a concrete saw. An experienced operator can cut 20 feet of 1 -inch-deep grooves in one hour. Heavier models are available for straight horizontal cuts, with cutting speeds up to 5 feet per minute. A sawed edge is much superior to a chipped edge, and sawing is generally less costly than chipping.

Surfaces within the trimmed holes should be kept continuously wet for several hours, preferably overnight, before placing the new concrete. The saturation of the old concrete will help in proper curing of the new concrete. Immediately before placement of the new concrete, the holes should be cleaned to leave a surface completely free of chipping dust, dried grout, and all other foreign materials that would deter bonding. Final cleaning of the surfaces to which the new concrete is to be bonded should be accomplished by wet sandblasting, followed by washing with an air-water jet for thorough cleaning; drying should be with an air jet.

All shiny spots indicating surface moisture should also be eliminated. Unnecessary tie wires should be removed from exposed reinforcement. Cleaning of the steel, if necessary, should be accomplished by abrasive blasting. All concrete repairs must be thoroughly moist- cured in order to be effective. If a high-strength bond is required and long moist-curing cannot be efficiently provided, either epoxy resin concrete or epoxy resin- bonded concrete can be used see Section 3. The preparations for the cast-in-place method of repair should be as follows: Excavation of irregular area of defective concrete where top of hole is cut at two levels.

Where a hole passes through a structural element, it may be necessary to fill the hole from both sides. In this case the slope of the top of the cut should be modified accordingly. When the hole goes entirely through the concrete section, spalling and featheredges can be avoided by having chippers work from both faces. All interior corners should be rounded to a minimum radius of 1 inch.

The construction and setting of forms are important steps in the procedure for satisfactory concrete replacement where the concrete must be placed from the side of the structu re. Form details for walls are shown in iFigure To obtain a tight, acceptable repair the following reguirements must be observed: The back form can be built in one piece. Sections to be set as concreting progresses should be fitted before concrete placement is started. In some cases, such as when beam connections are involved, a chimney may be necessary on both sides of the wall or beam. In all cases the chimney should extend the full width of the hole.

Twisted or stranded caulking cotton, folded canvas strips, or similar material should be used as the forms are assembled. This mortar should have the same sand and cement content and the front form is made up in sections for successive in. Details of forms for concrete replacement in bulkheads. The surface should be damp, but not wet. The mortar can be applied by means of an air-suction gun, by brushing, or by being rubbed into the surface with the hand encased in a rubber glove.

Concrete placement should follow immediately. If the cross- sectional area of the hole is greater than 36 and less than 72 square inches for reinforced concrete repair or square inches for nonreinforced concrete repair, a no-slump concrete should be placed, thoroughly vibrated, and power tamped in 3-inch layers. If practicable, the new concrete should be preshrunk by letting it stand as long as practicable before it is tamped into the hole. The mix proportions and the aggregate gradation should be selected for minimum water content.

Casting concrete in open-top forms, as used for the reconstruction of the top of bulkheads and pier-deck curbs, is a comparatively simple operation. No special features are required in the forms, but they should be mortartight when vibrated, and should give the new concrete a finish similar to that of the adjacent areas.

The slump should be as low as practicable, and the amount of air-entraining agent increased as necessary to ensure the maximum permissible percentage of entrained air, despite the low slump. Top surfaces should be sloped so as to provide rapid drainage. Manipulation in finishing should be held to a minimum, and a wood-float finish is preferable to a steel-trowel finish. Edges and corners should be tooled or chamfered. Water should not be used to aid in finishing. Forms for repairs involving cast-in-place concrete can usually be removed the day after casting unless form removal would damage the newly placed concrete.

The projections left by the chimneys should normally be removed the second day. If the trimming is done earlier, the concrete tends to break back into the repair. These projections should always be removed by working up from the bottom because working down from the top tends to break concrete out of the repair. Shotcrete is satisfactory for repairing minor damage to concrete piles and framed structures and should be considered whenever there is enough repair work to justify the cost of the equipment.

Piers, navigation locks, wooden piling, concrete piling, and steel piling are typical applications for shotcrete where waterfront repairs are necessary. The advantages of shotcrete, compared with either regular concrete or prepacked concrete, are: The comparative disadvantages of shotcrete are: Repairs and restorations accomplished by the shotcrete method are economical and successful where deterioration is shallow and the repaired area is large and irregular.

In regions of severe exposure, periodic protective applications are necessary to seal cracks that all ow the entry of wate r.

MAINTENANCE OF WATERFRONT FACILITIES

M ore i nformation can be found in Referenceslll andEO] With shotcrete, only that amount of water necessary for hydration is added to the mixture of aggregate and cement. Thus, shotcrete can be more dense than regular concrete, an important factor in the resistance of concrete to weathering. The ratio of cement to aggregate should never be greater than 1 to 3. The recommended shotcrete procedure for repairing a deteriorated waterfront structure is: Prepacked concrete is used on large repair jobs, particularly underwater placement or where placement of regular concrete would be either difficult or impossible.

This method is used also in restoring old concrete and masonry structures. The advantages of either regular concrete or prepacked concrete, compared with shotcrete, are: The comparative disadvantages of these two methods are that all work on vertical surfaces requires formwork, and for extensive restoration the plant required could be considerably more expensive than that required for shotcrete placement.

Prepacked concrete entails placing coarse aggregate in the form and filling the voids in the aggregate mass with intrusion grout that consists of Portland cement, a high grade pozzolan, sand, water and an intrusion aid. This makes it possible to restore deteriorated concrete members to near their original strengths or to enlarge existing members to take additional loads. Weakened material should be removed to expose sound concrete, and the surfaces of sound concrete should be roughened by either chipping or heavy sandblasting before repairing.

Space must be provided for the replacement or addition of at least 3 to 4 inches of new prepacked concrete. Forms are then well-anchored to the old concrete, filled with coarse aggregate of proper gradation for the thickness being placed , and the grout intruded. When the forms are filled, a closing pressure of about 10 psi is held for several minutes to drive out all air and water through a vent at the highest point.

The forms are removed one or two days later, and the new concrete is properly cured. One method of placing concrete underwater, especially at easily accessible locations, involves a tremie a steel tube having a hopper for filling at its upper end.

A plug, consisting of either a rubber ball or a wad of burlap that fits snugly inside the tremie, is inserted below a loading hopper located at the upper end of the tremie. The freshly mixed concrete, introduced at the hopper, forces the plug down and displaces the seawater. The tremie is continually replenished with concrete while the lower end is kept embedded in the newly deposited concrete.

Tremie concrete must be quite workable so that it flows readily into place. It is general practice to use a steel tremie, but a rigid rubber hose could be substituted. An aluminum alloy tremie should never be used because an adverse chemical reaction may occur to produce inferior concrete [3.

The slump of tremie concrete must be maintained between 6 and 7 inches. Pumping freshly mixed concrete is the most expeditious means of placing concrete in spaces of limited accessibility. The pumping method offers several advantages: The pumping method also has some disadvantages: Typical squeeze-type concrete pump. The squeeze-type pump KFiqure is preferred for pumping freshly mixed concrete into the form because few of the pump parts contact the concrete.

This pump is easy to clean and does not place the concrete under great pressure. When air-entraining agents are required as described in 3. Quantities needed per bag of cement are specified by the manufacturer and are shown on the containers. Normally about 2 fluid ounces per bag of cement are used. Water-reducing admixtures will also improve the pumpability of the concrete.

If admixtures are used, do not decrease the cement composition; to do so would probably cause blockage in the pipeline. Pumping The pipeline should be either horizontal or vertical rather than inclined, wherever possible. With an inclined pipeline any water bleeding from the freshly mixed concrete within the pipeline will collect above the concrete and run down the inside of the pipeline. The concrete should be pumped as near to its final underwater position as possible. The diver who has control of the discharge end should not permit lateral flow within the open-top form of more than 2 or 3 feet.

The discharge end of the line has to be buried in the mass of fresh concrete; otherwise, segregation will occur at the point where the concrete comes out. Aluminum pipe should not be used because an adverse chemical reaction with the concrete will occur.

Item Preview

Rubber hose should only be used for discharge lines or for very short pumping distances. The pipeline should be protected from any excessive heat solar included. Cracks and joints in concrete waterfront structures must be sealed against the adverse effects of a marine environment as a means of prolonging the lives of such facilities. Various formulations of epoxy resin compounds are used for sealing, grouting, patching, and waterproofing cracks and joints in concrete, and as adhesives for bonding freshly mixed concrete or precast concrete to old concrete.

No formulation can serve as an all-purpose material for these applications, and so each epoxy formulation should be used only for its intended purpose. Proper methods of treating the surfaces of concrete and reinforcing steel preparatory to applying the epoxy compound, and correct procedu res for using epoxy com pounds are described in detail in lReferences l through 3. Coating hardened concrete surfaces e. Throughout the 19th century, stone masonry was generally used in constructing graving docks, quay walls, and wharves. As late as the s, the cut stones of granite were set in lime mortar; after that, they were set in portland cement mortar.

The designers of masonry waterfront structures specified greater mass, proportional to the expected loads, than is customary with mass concrete used today. Granite masonry usually develops no maintenance problems except at the joints. The stone blocks in these old waterfront structures have been subjected to weathering, extraordinary loads, abrasion, and seawater.

The best visual indication of how well they have resisted weathering is their general appearance. Blocks of high- quality stone retain their sharp edges and corners and their delicate tool marks for many years.

After a century of service, these distinguishing attributes may no longer be present. Empty graving docks should be inspected for leaking groundwater through the joints in their stone floors and sidewalls and for leaking seawater around the seals of the closure to the basin. All joints should be examined for cracks and erosion. The earth behind the sidewalls should be inspected periodically for settlement. Movement of the sidewalls of a graving dock or quaywalls is usually revealed by an increase in width of cracks in adjacent paved areas atop the earth behind the walls.

If leaks are detected, note the rate of discharge and whether or not material is suspended in the water. Divers should investigate fo r scour and undermining, especially outside the closure IfFiaure TI. If settlement of the structure is suspected, establish points for a level survey; locate these points on both sides of each suspected joint and at both ends of the masonry structure; these points should be related to permanent bench marks established previously by the U. Coast and Geodetic Survey.

For a graving dock, these points should be located at the tops of the sidewalls, at the floor adjoining the sidewalls, along the longitudinal centerline of the floor, and along the outer rail of the crane track. Note any condition that could reveal settlement. Types of deterioration that will require repair. If a masonry quaywall or graving dock has moved as the result of sliding at the foundation, a structural analysis to determine the cause is necessary before any restoration is attempted.

An investigation of the settlement may involve pumping dyed water through cracked or leaky joints to determine the extent of hidden cavities or voids; the existence of a cavity would be confirmed by finding the colored water at some drainage outlet. After such an investigation has yielded the location, depth, and extent of the cavity or void, a program of grouting must be planned.

If any portion of the masonry structure is damaged, or if any stone blocks are loose, repairs should ensure that the bond between the blocks is restored. If a masonry quaywall or sidewall of a graving dock is cracked due to unequal settlement, restoration should be delayed until the cause of settlement has been corrected. If there is evidence that water is collecting behind the quaywall, and if weep holes are part of the installation, the holes should be cleared to allow drainage. If this procedure is insufficient to relieve the pressure, additional weep holes should be drilled.

Shrinkage cracks in joint mortar appear as hairline cracks; they are usually found in vertical joints. If the masonry exhibits signs of leakage, hairline cracking can also be present in the horizontal beds of mortar. Spalled mortar can be caused by many cycles of alternate freezing and thawing. Defective joints can usually be repaired by tuck-pointing with portland cement mortar; a skilled stone mason is required. Tuck-pointing only the obviously defective joints does not ensure that the untreated joints will not leak; therefore all joints, vertical and horizontal, in the face of the wall should be tuck- pointed.

Each joint is raked to a depth not greater than 1 inch, unless the old mortar is so defective that removal to a greater depth is necessary. The depth of old mortar removed should be such that sound mortar will serve as the base for the new mortar. All exposed sound mortar must have a clean, square-cut surface. All dust and dirt within the raked joint should be washed out by a jet of water. Wherever old mortar is raked out deeper than 1 inch, the hollow spots must be filled with new mortar first so that a uniform line is created.

The cleaned joints are tuck-pointed with the Portland cement mortar while the masonry is still damp not wet from washing out the raked joints. A suitable mortar incorporates a special masonry cement Type II Portland cement and a plasticizer , silica sand, and freshwater. It has a somewhat stiff consistency to enable it to be tightly packed into place. Placement should be done as follows: Leaky stone masonry structures can be sealed effectively with less cost by using grout, provided the cement-base stabilizing mixture contains an intrusion aid.

The consistency of the intrusion mixture is that of a smooth slurry. This mixture is pumped into holes previously drilled at various intervals to various depths without damaging the integrity of the structure. Before the intrusion grout is pumped, the holes are tested by pumping water to see if the drilling is adequate and to determine the correct consistency for the slurry repairs. The pressurized injection of latex siliconate, a method of grouting developed during the s, has been successfully u sed in England for making masonry structures watertight l[]l.

A mound is an artificial embankment or ridge composed of sand, gravel, and cobbles, constructed on the oceanic floor by dumping the material from scows and barges. The dumping operation continues until the mound emerges a certain distance above the mean seawater level. Wave action on the mound gives the sides a natural stable slope. Since wave action decreases as the oceanic depth increases, the natural side slopes of the mound normally are steeper in deeper water; this is a function of top elevation of the mound, bottom configuration, and tidal range.

Rubble-mound structures are used extensively, because they are adaptable to most any depth of water in the vicinity of harbors and can be repaired readily. If the oceanic floor is not rocky, rubble can protect the floor against scouring that otherwise might occur at the foot of the mound. Rubble is irregularly shaped, rough stones, ranging in size up to 1, cubic feet each and in weight up to nearly 90 tons each. The stones are in the same condition as when quarried but without any preparation i.

• Special offers and product promotions.
• .
• Maintenance of Waterfront Facilities - Google Книги.
• Situaciones difíciles en terapia (Manuales Prácticos) (Spanish Edition).

Hard rock, which is more desirable, usually consists of either granite or traprock fine-grained igneous rock. Limestone, dolomite, and sandstone are undesirable because of their lesser hardness, toughness, and durability. Since the rubble used as riprap must be available in large sizes, the quality, condition, and shape of stone are important.

Each piece should be devoid of planes of weakness, have a specific gravity not less than 2. Massive, compact, fine-grained igneous rock is the best source of rubble. Riprap is a mixed assemblage of rubble, either dumped indiscriminately as a foundation for the waterfront structure from scows and barges or deposited on the surface of a mound to protect the mound against erosion by waves and scouring by tidal action and underwater currents.

Where it can be procured in large quantities at low cost, riprap can be useful as a filter blanket over a sandy bottom, as fill behind moles and quaywalls, and as protection for the sloping sides of mounds. The riprap in older breakwaters consists of large cubical or rectilinear blocks of quarried stone. Since , a number of precast concrete armor units have been developed; th e prevalent types are tetrapods, tribars, and dolosse Figure 5-TI.

Smaller concrete armor units can often be substituted for larger quarry stones and still obtain comparable protection of the a Tetrapod. No reinforcing steel or steel lifting eyes are used in dolosse and tetrapods; consequently, corrosion is not a problem, and unit cost is minimized. Dolos and tetrapod units are less vulnerable to damage during placement and storms than the various other types of concrete armor units.

The Army Engineer Waterways Experiment St ation considers the dolos armor unit the most efficient The three principal types of deterioration in rubblemound structures are: Scour at or near the base of a rubblemound structure does not normally occur if the structure is correctly designed and the floor is stabilized by means of a properly designed filter blanket and ample riprap.

However, if one or more groins should be subsequently installed at incorrect locations nearby, then radical changes in currents and their velocities could adversely influence the base of the structure. A seawall can suffer loss of riprap; this successively leads to erosion, by subsequent wave action, of the toe of the structure and later to undermining of the base. Correctly designed, located, and constructed groins seldom undergo damage by wave action, be cause the l ittoral drift tends to fortify the structures [Figure l.

Ideally, the shoreline remains stable as long as the rates of deposit and erosion are equal. If the erosion rate the deposition rate, the shore decreases in area, and the groin is then subjected to gradual destruction. Breakwaters are often subjected to extreme wave action that dislodges riprap and washes out portions of the mound.

During violent storms, sections of a breakwater can occasionally be broken through. A typical rubble-mound breakwater is shown in I Figure 5. Jetties are designed to direct the flow of currents and tides through the entrance channel so as to ensure a minimum velocity.

TM Maintenance of Waterfront Facilities | WBDG - Whole Building Design Guide

Though to all outward appearances they may be satisfactorily sustaining the pressure, the flowing water can gradually scour the base material on the channel side and eventually cause either subsidence of a portion of the jetty or sloughing of the riprap comprising the side slopes. Cross section of semipermeable rubble-mound groin. The inspection should provide for detecting beginning weaknesses in the bases of these structures e. The crown of a rubble-mound structure is inspected visually on foot; the portions above water level are inspected visually from a dinghy or small craft; and the portions below the water line are inspected by divers or underwater TV cameras.

The intended depth of the structure is determined from the design drawings; the as-built depth should be compared with depth data obtained by soundings taken at stations that are located at equidistant intervals. As much of the structure as possible should be inspected at low tide. If scouring or sloughing is apparent an engineering investigation should be initiated.

The inspection by the divers when tidal conditions and wave actions permit may be able to verify the indicated deficiency or damage. Underwater television can be effective as a visual means of inspection, but is frequently negated by turbulence, suspended sediment, or inability of the operator at the surface to maneuver the apparatus readily. A rubble-mound mole requires proper drainage of backfill to prevent a pressure differential. Visual inspection of the surface of the backfill will reveal any discrepancies concerning drainage.



1. The Son of Sun and Sand (Consortium of Chaos Book 2)!
2. Coming Home for Christmas.
3. .
4. !
5. Murder in the Roaring Twenties (Murder Mystery Plays Book 2);
6. Manners (Part 2) (Islam Questions And Answers Book 18)?

Dredging alongside a rubble-mound mole must be restricted to depths not greater than contemplated in the original design. If any portion of the base becomes undermined e. If the backfill in either a mole or seawall shows evidence of settling e. Stabilization of the backfill, either by replacing the lost fill with properly graded material in the filter blanket and in the c ore or by careful grouting, may correct the problem see l Chapter!

About WBDG

After stabilizing the backfill, all defective pavements should be repaired to prevent any erosion of the underlying backfill. Drawings showing the construction as actually built, rather than as originally designed, should be used in preparing plans for repair of rubblemound structures. All drawings and records pertaining to any previous repairs should be reviewed before undertaking new repairs.

Maintenance on rubble-mound breakwaters is greater than on any of the other types. Proper grading of the seaward slope and Figure Cave-in, indicating settlement of mole. Any material lost through scouring and washing must be replaced periodically with materials of the same kind and size as used originally. Adjustments in seaward slope may be necessary. Material should not be replaced to the original slope if investigation shows that a change is in order. A change in the type of capping material also may be necessary with the passage of time, and use of concrete tetrapod, tribar, or dolos armor units may improve the structure.

If large facing and capping stones are set in a tight pattern, the vertical joints between the stones may need venting by leveling the corners of individual stones to permit entrapped air and water to escape. This reduces the lifting action beneath the stones and improves their stability. The replacement of riprap after replacement of any material washed out of the mound should either retard or prevent further scouring. If the scour is produced only by wave action, the problem can be solved by fortifying the toe of the structure with a thick layer of riprap which serves to stabilize the bottom; the rubble must be carefully emplaced so that the smaller stones become wedged in the spaces between the larger stones.

The minimum dimension of any stone should be at least one-third of its maximum dimension. If the scour is caused by offshore underwater currents, installation of groins at strategic locations along the shoreline may be necessary. If the bottom is scoured so extensively that the stability of the structure is endangered, an underwater groin consisting of very heavy rubble may be effective in deflecting the underwater current; in such an installation, the groin is designed to accumulate waterborne material so that the floor around the foot of the structure builds up and serves as a stabilizing influence.

Rubble-mound breakwaters, jetties, and seawalls occasionally are repaired by adding crushed stone to the crowns and seaward slopes and grouting the new surfaces. Repairs of this type, which must be made in stages because of tides, must produce a thick 3 feet or more pro tective layer or blanket of grouted stone, repairs. The grouted sheathing of face of a breakwater, which is exposed to storms. Earthworks, consisting of soil materials generally enclosed within a protective covering of coarse stone riprap, steel, or concrete skins, are used for waterfront structures, such as dikes, levees, breakwaters, causeways, groins, and seawalls.

Soil generally provides the backfill for quaywalls, caissons, and other cellular structures. The most common cause of deterioration and damage to such structures is erosion of the soil by water movements, gene rall y due to wind, tidal, or wave action [References and Any breaching of or impairment to an earth structure exposed to moving water sharply increases its susceptibility to damage. For this reason it is very critical that any required maintenance be identified and carried out as quickly as possible.

Soil is composed of particles that differ physically in size and shape and vary in chemical composition. Organic matter, water, air, and bacteria are usually present, but soil consists essentially of mineral matter that has originated from rocks by the action of a series of weathering processes.

The complete description of a soil includes: With reference to soils used in waterfront structures it is often sufficient to classify them only according to size i. The density, plasticity, and moisture content are most important for the finer-grained soils, while soundness and gradation are most pertinent to the coarser-grained soils and rock fills.

The particle size, which marks the boundary between the fine-grained, generally cohesive soils silts and clays and the coarse-grained, granular soils sands and gravels , is approximately the smallest sized particle that is large enough to be individually discernible to the naked eye. This is the minimum size retained on the no. Organic soils, such as elastic silts and peats, are never used in the construction or repair of engineering structures, and, therefore, will not be considered herein.

We have an excellent opportunity for a reliable and motivated individual to join our team at our new unit luxury waterfront apartment and marina community How long does it take to get hired from start to finish? What are the st What questions did they ask during your interview? This position is responsible for maintenance of all City facilities and land but not limited to general building repairs and maintenance , utilities maintenance Burlington, Vermont - City of Burlington, Vermont. Chief Engineer Marriott International, Inc 19, reviews.

Job Category Engineering and Facilities. Establishes and manages an effective rooms maintenance program What is the interview process like? How are the working hours? Chief Engineer - Boston, Massachusetts. Previous maintenance experience or equivalent training required. Assist with preventative maintenance and complete work orders related to replacing and Hersha Hospitality Management - 8 days ago - save job - more Preventative Maintenance in Guestrooms.

Responds to maintenance emergencies timely. If you were in charge, what would you do to make OTO Development a bette University Press of the Pacific January 26, Language: Be the first to review this item Amazon Best Sellers Rank: I'd like to read this book on Kindle Don't have a Kindle? Share your thoughts with other customers. Write a customer review. There's a problem loading this menu right now. Learn more about Amazon Prime. Get fast, free shipping with Amazon Prime. Get to Know Us.