Marine Outfall Performance. I: Introduction and Flow Restoration

Sewage outfalls are common inclusions in the infrastructure of coastal cities and towns. Near-ocean industries may also make use of such pipes. Keeping such a conduit operating properly is by no means a trivial matter, and this paper is the first of two dealing with this complex topic. Herein, the various failure and impairment mechanisms are summarized, and the need for careful underwater inspection is stressed. Examples are given of inspection, maintenance, and repair operations for various municipal facilities. The paper closes with presentation of two improvement procedures, pigging and sliplining.     

Mixing of a Rosette Jet Group in a Crossflow

Partially treated wastewater is often discharged into coastal waters through an outfall diffuser fitted with clustered ports on risers. On each riser the effluent is discharged through two to eight ports arranged circumferentially, in the form of a rosette-shaped buoyant jet group. The near field mixing of such a jet group in a tidal flow is determined by the merging and interaction of coflowing, oblique-flowing, cross-flowing, and counterflowing jets. Despite numerous studies, a general predictive method for such complex jet groups has not been reported; ocean outfall design is often based on comprehensive physical model experiments. The mixing of merging nonbuoyant and buoyant jets issuing from a rosette outfall riser into an ambient current is studied experimentally by using the laser-induced fluorescence technique. Detailed cross-sectional measurements of the scalar concentration field downstream of the bent-over jets are made. The trajectories of multiple and individual jets discharging at various angles are measured. For typical outfall designs, the dynamic interaction of adjacent jets is found to be negligible. The average dilution of the jet group can be predicted by accounting for jet merging and plume overlapping. Theoretical predictions using the Lagrangian VISJET model are in excellent agreement with the experimental data and also results of previous studies in a stratified crossflow. The model correctly predicts the changes in near field dilution as a function of the number of nozzles on a riser, or the number of risers on a diffuser, and helps to resolve observed anomalies in previous studies.     

Marine Wastewater Discharges from Multiport Diffusers. IV: Stratified Flowing Water

Experiments on the near-field mixing of wastewater discharged from multiport diffusers into stratified flowing waters are reported for conditions typical of actual ocean sewage outfalls. Dilutions were measured by a newly developed three-dimensional laser-induced fluorescence system combined with refractive-index matching and by a microconductivity probe. The plume dynamics are complex. Depending on port spacing, plumes discharged from the upstream diffuser side may merge first with themselves, and then with the plumes discharged from the downstream side. Or the plumes that are horizontally opposed may first merge, followed by lateral merging. In all cases, however, the wastefield eventually becomes laterally homogeneous. The results are analyzed in terms of line or point-source parameters and it is found that they can be predicted by assuming the discharge to be a line plume when s/lb<1.0 and as point plumes for s/lb ≥ 6.0. Semiempirical equations to predict the near-field dilution, near-field length, and plume rise height are presented.     

Considerations for Storm-Water Outfalls off Exposed Coasts

There is a worldwide movement for coastal municipalities in developed countries to replace whole series of storm drains with far fewer storm-water outfalls that discharge well offshore. Such an extended-length pipe, passing into the surf zone along an exposed coastline, is far from easy to plan, support with data, design, install, and operate. This paper is intended to school drainage engineers in these matters.     

Marine Outfall Performance. II: Stabilization and Case Studies

This paper, the second in a series, outlines the various methods that can be used to immobilize and protect an exposed outfall pipe that appears vulnerable to destabilizing agents such as waves, ice, logs, or fishing trawls. Measures covered include the placing of quarry rock or articulated concrete block mats, the driving of piles, and the installation of stapling arrangements. Case studies cover various specific outfalls where particular stabilization measures were employed. Environmental considerations are included.     

淮河入海水道工程规划与移民安置规划的有机结合

为妥善解决移民生产和生活问题，淮河入海水道工程必须与移民安置规划有机结合起来，使入海水道工程的建设促进和改善农田的灌溉、防洪、排涝、降渍条件；结合当地资源优势，广开就业门路；结合航运发展地区经济；同时，即要保障上游安全，也要兼顾下游地区的经济发展，为下游地区的经济发展创造优越的自然环境。     

Dual Multilevel Urban Drainage Model

In urban areas, when heavy rains occur, the discharge capacity of sewers is usually unable to transport the effective rainfall reaching the streets. When the runoff flow rate exceeds the capacity of the storm sewer system, the excess flow is conveyed through the street network as overland flow. A dual model is proposed for modeling the system as a double network, formed by an upper network of open channels (street gutters) and a lower network of closed conduits (sewer pipes). What is new in this model is its capacity to take into account the hydrodynamic relationship between the flows in the upper and lower networks. The model is applied to computing the response of a real monitored basin; the historical flow rates measured during a first rainfall event are used to calibrate the model, which is then validated using the simulation of two other measured events.     

Deposition from Particle-Laden, Round, Turbulent, Horizontal, Buoyant Jets in Stationary and Coflowing Receiving Fluids

Results are presented from a series of laboratory experiments investigating the characteristic features of particle-laden, round, turbulent, buoyant jets discharged horizontally into stationary and coflowing receiving fluids. For the volumetric source concentrations of particles tested ( ～ 0.1%), the presence of the particle load was found to have no significant influence on mean buoyant jet trajectories. Deposition patterns on the bed of the receiving water container indicated the existence of two separate sedimentation processes for discharges into stationary or coflowing ambients, namely (1) a relatively concentrated, narrow band of particle accumulation associated with near-source fallout from the buoyant jet margins; and (2) a broader and more disperse downstream depositional fan associated with particle fallout from the radially-expanding surface gravity current formed by the impingement of the buoyant jet with the free surface of the receiving fluid. Scaling arguments have been developed and applied successfully to deposition length scales associated with these sedimentation patterns, allowing the quantitative characteristics and parametric dependences of the deposition distributions to be established.     

凌云县污水处理厂入河排污口对澄碧河的影响

分析了凌云县污水处理厂入河排污口有关信息。在满足水功能区保护要求的前提下,论述了入河排污口设置对水功能区、水生态和第三者权益的影响。根据纳污水体的纳污能力、排污总量控制范围、水生态保护等要求提出水资源保护措施。     

Marine Wastewater Discharges from Multiport Diffusers. I: Unstratified Stationary Water

Laboratory experiments on the near-field mixing of buoyant plumes discharged from multiport diffusers into unstratified stationary water are reported. Dilution was measured by a newly developed three-dimensional laser-induced fluorescence system and a microconductivity probe. Significant additional mixing (and dilution) occurs beyond the point where the plume impacts the water surface. This mixing ceases when the turbulence generated by the plumes collapses in the surface spreading layer. The port spacing, s, was varied through a range encompassing line to point source conditions. In all cases, the concentration distribution in the surface layer eventually becomes laterally uniform. Measurements of the near-field dilution, length, and layer thickness, and semiempirical equations to predict them are presented. The discharge behaves as a line plume when s/H ? 0.3, and as a point plume when s/H ≥ 1.0. The additional near-field mixing for a point plume is much greater than for a line plume. Basing diffuser design on near-field dilution rather than impact-point dilution allows the use of far fewer ports, or risers, with considerable potential cost savings, particularly for tunneled outfalls.