Showing papers on "Dredging published in 1986"

River Response to Dredging

Abstract: Examination of the impact of dredging when employed in support of engineering requirements for river system development on the Mississippi River system reveals that the dredge provides the river engineer with a means of rapidly altering channel configuration and accelerating morphologic processes. In this respect, dredging constitutes a morphologic agent responsive to engineering requirements. This application is overshadowed by the volume of material moved and the number of reaches involved in dredging operations for navigation channel maintenance. Dredging and disposal of dredged material in support of channel maintenance implies the repeated moving of alluvial sediments from the main channel region toward the periphery of the channel. The combined use of dredging, contraction dikes, and disposal of dredged material in the dike fields can induce major changes in the cross‐sectional characteristics of a river. This direct physical displacement of bed material and the resulting change in channel shape can...

Effects of Suction Gold Dredging on Fish and Invertebrates in Two California Streams

Abstract: I examined the impact of small suction dredges (hose diameter, <16 cm) on fish and invertebrates in two California streams (North Fork of the American River and Butte Creek) in a 2-year study. I studied both the effect of one dredge (1980) and the effects of an average of six dredges in a 2-km section of stream (1981). Ten replicate Surber samples per station were taken monthly to compare macroinvertebrate abundances at control and dredged stations before, during, and after dredging in both years. Dredging significantly affected some insect taxa when substrate was altered. A recolonization experiment showed that numerical recovery of insects at dredged sites was rapid. Mask-and-snorkel censuses and observations of tagged fish indicated that major changes in available habitat caused local decreases in fish density. Dredging affected riffle sculpins (Cottus gulosus) more severely than rainbow trout (Salmo gairdneri), probably because of differences in microhabitat requirements. Local turbidity incr...

Impact of offshore dredging on beaches along the genkai sea, japan.

Abstract: Offshore dredging has been taking place in the coast of the Genkai Sea, Japan, since the early 1970's, which totaled more than 20 million cubic meters. In order to evaluate the impact of offshore dredging on shorelines as well as the adjacent sea bed, comprehensive coastal engineering studies were carried out over the last four years. The results obtained are not sufficient to establish a direct cause-andeffect relationship between offshore dredging and beach erosion; however, the correlation is sufficient to serve as a warning of a potentially serious problem. Moreover, the dredged holes above 30 meter depth are found to trap the sand from the neighboring bed, and considerable movement of sediment by wave action was observed above 3 5 meter depth. Thus, offshore mining that would minimize interruption of beach littoral system should be operated below 35 meter depth in the study area.

Dredging barge for works on an urban site in particular

Abstract: The present invention relates to a dredging barge especially adapted for works on developed sites and in particular on an urban site. The barge is equipped with a boom 21 at the bow and provided on the one hand, with means for discharging the dredging materials and, on the other hand, advancing and stabilising means arranged respectively at the stern part and at the bow part; it furthermore comprises means for varying the draft, consisting of longitudinal ballast tanks, and means making it possible to vary the total height above designed water line.

Guide to Selecting a Dredge for Minimizing Resuspension of Sediment. Environmental Effects of Dredging

Abstract: : This technical note contains assessments of conventional and special-purpose dredges in removing sediment with minimal sediment resuspension. If sediment resuspension is a critical factor in dredging areas of contaminated material, the following guidance will aid in specifying the dredge and operating conditions. Investigations were conducted as part of the Corps of Engineers' Improvement of Operations and Maintenance Techniques (IOMT) Research Program to evaluate the resuspension of sediment into the water column due to dredging operations. Laboratory, field, and literature studies have been used to define the sediment resuspension characteristics of most conventional and several special-purpose dredges. The natural hydrophobic tendency of most organic contaminants and the high sediment-sorptive capacity for inorganic contaminants limits release to the soluble forms and makes the simple measure of sediment resuspension during dredging a relative measure of the potential for contaminant release.

Building, Developing, and Managing Dredged Material Islands for Bird Habitat

Abstract: : This note describes the environmental considerations and techniques that have been developed and tested for building, developing, and managing dredged material islands for use by birds for nesting and other life requirements The text of this note was taken from lectures presented from 1979 to 1986 at the Dredging Short Courses held each year by the Texas A&M University Center for Dredging Studies and from information compiled for Engineer Manual EM 1110-2-5026 entitled "Beneficial Uses of Dredged Material"

Dredging Operations and Waste Disposal

Abstract: Dredging is an operation for the removal of silt, sand, clay, and miscellaneous materials from underwater surfaces by excavation, and the subsequent conveyance to and disposal of the material at an appropriate disposal site. It is thus doubly important environmentally—in the area of removal and in that of accumulation—besides having other, often significant side-effects. In general, there are two types of dredging operations: new-work dredging and maintenance dredging. The former comprises the improvement (i.e., deepening or widening) of a channel and/or harbor area by removing mainly stones and compacted sediments that were deposited through the geologic ages. The latter is employed mainly to remove the loose sediments that tend to fill up previously excavated channels.

Automatic dredging control device for drag suction dredger

Abstract: PURPOSE:To preform high efficient dredging work, by a method wherein, by means of signals from a sensor group detecting operation of various detectors, operation and attitude of a drag arm and control of a dredging pump are automatically performed. CONSTITUTION:When the whole of a dredging work is selected to operation by an automatic control 21, based on signals from a drag arm, a sensor group located to a dredging pump, various devices are automatically controlled. In the automatic control, drag arm control 22, automatic dredging attitude control 23, mud loading control 24, dredging pump control 25, and damping control 26 are continuously performed based on a given control pattern previously set. This relieves burden on an operator, and decreases unevenness in dredging efficiency produced by an operator, and enables to perform efficient dredging work.

Nautical Bottom Research and Survey for Optimization of Maintenance Dredging in Mud Areas

Abstract: There is a definite need to better define a uniform and exact nautical bottom within loose mud deposits, characterized by low shear strengths in their upper parts. This chapter presents a better approximation of a mud nautical bottom definition, based mainly on the rheological characteristics of the mud considered. From the results it will be clear that a direct application of this theory in the field is possible. Maintenance dredging can be optimized in two ways, by introducing such a definition of the nautical bottom a better definition of the target depth for piloting the dredging works; the possiblity of better and more uniform production work.

Environmental Effects of Dredging: Guide to Selecting a Dredge for Minimizing Resuspension of Sediment.

Abstract: : This technical note contains assessments of conventional and special-purpose dredges in removing sediment with minimal sediment resuspension. If sediment resuspension is a critical factor in dredging areas of contaminated material, the following guidance will aid in specifying the dredge and operating conditions. Investigations were conducted as part of the Corps of Engineers Improvement of Operations and Maintenance Techniques (IOMT) Research Program to evaluate the resuspension of sediment into the water column due to dredging operations. Laboratory, field, and literature studies have been used to define the sediment resuspension characteristics of most conventional and several special-purpose dredges. The natural hydrophobic tendency of most organic contaminants and the high sediment-sorptive capacity for inorganic contaminants limits release to the soluble forms and makes the simple measure of sediment resuspension during dredging a relative measure of the potential for contaminant release.

Forum to Review Confined Disposal Facilities for Dredged Materials in the Great Lakes.: Report of the Dredging Subcommittee to the Great Lakes Water Quality Board

Abstract: C o n f i n e d D i s p o s a l F a c i l i t i e s i n t h e C a n a d i a n G r e a t L a k e s R . S e a w r i g h t . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C o n f i n e d D i s p o s a l P r o g r a m f o r P o l l u t e d M a i n t e n a n c e D r e d g i n g i n t h e G r e a t L a k e s R . N e a l . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S e l e c t e d C a s e S t u d i e s t o I l l u s t r a t e E n v i r o n m e n t a l C o n s i d e r a t i o n s i n P l a n n i n g C o n f i n e d D i s p o s a l F a c i l i t i e s W i t h i n U n i t e d S t a t e s W a t e r s : A R e v i e w o f A n a l y s i s a n d D o c u m e n t a t i o n R e q u i r e m e n t s P . E . B e r k e l e y a n d W . F . M a c D o n a l d . . . . . . . . . . . . . . . . . . . . . . . . . . . . I n t e r a g e n c y a n d P u b l i c I n v o l v e m e n t i n S i t i n g C o n f i n e d D i s p o s a l F a c i l i t i e s P . M o h r h a r d t . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P u b l i c P e r c e p t i o n s R e g a r d i n g C D F s a n d T h e i r I n f l u e n c e i n S i t i n g D e c i s i o n s f o r T o r o n t o H a r b o u r B . L e e . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S i t e S e l e c t i o n , D e s i g n a n d C o n s t r u c t i o n E x p e r i e n c e s w i t h C D F s i n U n i t e d S t a t e s W a t e r o f t h e U p p e r G r e a t L a k e s B . M a l a m u d . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P r o c e d u r e s f o r P r e d i c t i n g E f f l u e n t Q u a l i t y a n d S t o r a g e C a p a c i t y a s D e s i g n C r i t e r i a f o r C o n f i n e d D i s p o s a l F a c i l i t i e s M . R . P a l e r m o . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . T h e C o s t o f C o n s t r u c t i o n , O p e r a t i o n a n d M a i n t e n a n c e o f t h e C o n f i n e d D i s p o s a l F a c i l i t y a t T h u n d e r B a y , O n t a r i o E . 8 . A s h t o n a n d L . O t w a y . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C O N T E N T S ( C o n t ' d . ) O p e r a t i o n a l a n d F i n a n c i a l C o n s i d e r a t i o n s i n F i l l i n g , M a i n t a i n i n g a n d M a n a g i n g C o n f i n e d D i s p o s a l F a c i l i t i e s S . R . J a c e k . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . O p e r a t i o n s a n d M a n a g e m e n t o f t h e D i s p o s a l F a c i l i t y T o r o n t o H a r b o u r K . S . F r i c b e r g s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . R e s e a r c h S t u d i e s f o r P r e d i c t i o n a n d C o n t r o l o f L e a c h a t e s f r o m C o n f i n e d D i s p o s a l F a c i l i t i e s N . R . F r a n c i n q u e s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . L o n g T e r m M o n i t o r i n g o f T i m e s B e a c h a n d O t h e r C o n t a m i n a t e d C o n f i n e d D i s p o s a l S i t e s J . W . S i m m e r s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C o n t a m i n a n t M o b i l i t y S t u d i e s f o r T i m e s B e a c h C o n f i n e d D i s p o s a l F a c i l i t y , B u f f a l o , N e w Y o r k R . P . L e o n a r d . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C h i c a g o A r e a C D F S y n t h e t i c L i n e r a n d S a n d B l a n k e t E x p e r i e n c e C . S a v a g e . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C h i c a g o A r e a C D F F i l t e r C e l l P e r f o r m a n c e J . A . M i l l e r . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S t a t u s a n d T r e n d s o f C o n t a m i n a n t s i n H a r b o u r a n d C h a n n e l S e d i m e n t s i n t h e C a n a d i a n G r e a t L a k e s A . M u d r o c h . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S t a t u s a n d T r e n d s o f H a r b o r S e d i m e n t C o n t a m i n a t i o n i n t h e U n i t e d S t a t e s L o w e r G r e a t L a k e s J . R . A d a m s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D r e d g i n g a n d C o n f i n e d D i s p o s a l F a c i l i t y O p e r a t i o n a l M o n i t o r i n g f o r U n i t e d S t a t e s H a r b o r s i n t h e U p p e r G r e a t L a k e s S . R . J a c e k a n d R . S c h m i t t . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . W i l d l i f e U t i l i z a t i o n a n d M a n a g e m e n t o f t h e C o n f i n e d D i s p o s a l F a c i l i t i e s i n t h e G r e a t L a k e s M . C . L a n d i n . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A C a s e S t u d y o f H a m i l t o n H a r b o u r C o n f i n e d D i s p o s a l F a c i l i t y J . G r o s s i . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A C a s e S t u d y o f S o u t h E a s t B e n d / S t . C l a i r R i v e r C o n f i n e d D i s p o s a l F a c i l i t y T . E . D o u g l a s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 3

Soil dredging and disposing device

Abstract: PURPOSE:To conduct crashing of coarse sediment on a sea bottom simultaneous ly with dredging without worsening environment, by a method wherein a screw cutter, moving in and out with the aid of a link mechanism, is mounted in the soil dredging hopper of a soil collector bulldozer. CONSTITUTION:A soil collecting bulldozer 13 is lowered on a sea bottom, a jet current is produced within a soil dredging hopper 30, an screw cutter 35 is rotated, and a cylinder 44 is moved backward. This causes a screw cutter 35 to approach and part from the sea bottom through the working of a link mechanism 36 to crash coarse sediment on the sea bottom to agitate it together with solid soil. The crashed substance is sucked through a soil suck flexible pipe, and is guided to a separating tank in a barge body. Mounting of the screw cutter 35 enables crashing of the coarse sediment on the sea bottom simultaneously with dredging without worsening environment, and enables simpli fication of a work.

Grab bucket with compressed air case

Abstract: PURPOSE:To perform dredging work without formation of turbid water by excavating the bottom ground under water by a bucket provided in a compressed air case in a freely opening and closing manner while supplying compressed air to the compressed air case whose downside is opened CONSTITUTION:A bucket 13 to be opened or closed by a central oil-pressure jack 14, an arm oil-pressure jack 15, and an auxiliary arm oil-pressure jack 16 is provided in a compressed air case 27 to form a grab bucket 11 for excavation and dredging work In dredging the bottom ground under water, compressed air is supplied into the case 27 from a supply port 32, and the case 27 is penetrated into soil while preventing the intrusion of water These jacks 14-16 are properly extended or contracted, and the bucket 13 is closed in such a way that the cutting edge 33 of the bucket draws a line of locus G Under the condition, the whole body of the grab bucket 11 is lifted up through a wire rope 12, and dredging work is performed without formation of turbid water

Detection of dredged sludge amount in sludge dredger

Abstract: PURPOSE:To grasp exactly the advancing condition of dredging work by a method in which a gyroscope for detecting the swinging angles of a suction head is provided, an echo sounder is provided in a given direction from the swinging direction, and the dredging work amount is calculated. CONSTITUTION:Echo sounders 6F and 6B capable of measuring the distance of sludge 5 of seabed from the sludge face are set at the distance of about 1m on the front side F and back side B at almost right angle to the swinging direction S of a suction head, by which the depth of dredging work is detected. The swinging width is detected by a gyroscope 8 and the dredging amount is calculated from the detected values of swinging width and dredging depth. By detecting the swinging speeds of the head 3, the efficiency of dredging work can be known. Since the dredging amount can be soon obtained during the dredging work, the advancing condition of the dredging work can be determined to make the construction administration of the dredging work easier.

Challenging the dredging concept

Abstract: A new system now operating at Nerang River, Queensland, Australia, to combat siltation is described. It challenges the conventional dredging works approach to controlling siltation, in that it features a permanently-installed and purpose-designed submerged sand pump.

Long-Term Effects of Dredging Operations Program. The Duwamish Waterway Capping Demonstration Project: Engineering Analysis and Results of Physical Monitoring.

Abstract: : This paper summarizes the initial fieldwork and presents results through the first (6-month) monitoring effort for the subaqueous disposal and capping of contaminated dredged material on the Duwamish Waterway, Seattle, Washington. Keywords: Capping; Contaminated sediments; Dredging--disposal techniques; Duwamish waterway; Open-water disposal.

Dredging base ship capable of reciprocal excavation

Abstract: PURPOSE:To permit dredging operations to be performed all the time regardless of the moving direction of a dredging base ship by a method in which a sucker is connected through a flexible hose and a ball joint to the tip of a transport tube provided downwards from the dredging base chip. CONSTITUTION:A transport tube 5 is provided downwardly in water from a dredging base ship 1, and a flexible hose 14 is connected to the tip of the tube 5. A sucker 13 is attached to the tip of the hose 14 in a vertically rocking manner. An air supply tube 7 is also connected through the base ship 1 to the neighborhood of the connection between the tube 5 and the hose 14. The sucker 13 is suspended from the ship 1 by a cable 21 and follows the moving direction of the ship 1 during dredging operation only by altering the direction of the hose 14. The reciprocal dredging operation of the dredging ship can thus be made possible.

Mud accumulation in estuarine channels ‐ a question of dredging?

Abstract: For two coastal plain estuaries, the Elbe and the Weser, hydrographic data and 170 years old and recent depth maps are used to test the hypothesis that overdeepening by dredging causes mud trapping in the estuarine channel. As a result, this hypothesis seems to give the safest interpretation for this kind of mud shoaling, although evidence is not absolute.