Robert Dresnack

Review of Bridge Scour Practice in the U.S.

For years bridge designers in the U.S. have used FHWA Publication Hydraulic Engineering Circular No. 18 (HEC 18) as a principal tool to determine scour depths. Increasingly, though, practitioners recognize that some of the circulars standard equations over predict scour depth for certain geologic and hydraulic conditions. In an effort to improve scour design and evaluation methods, the New Jersey Department of Transportation (NJDOT) recently conducted a survey of current scour practice of DOTs across the U.S. The ten-question survey queried agencies about their design standards, experiences with failures, monitoring programs, and countermeasure preferences, among other things. This paper presents the results of the nationwide scour survey. Highlighted are the creative and diverse approaches by some states to either modify HEC 18 procedures or develop alternative scour prediction methods. The paper also discusses critical geologic, hydraulic, and hydrologic parameters for rational evaluation of scour depth, gleaned from both the survey and local experience with New Jersey bridges.

Mechanism and feasibility of colloidal particle removal by a microcarrier process

Pollutants associated with colloidal particles in stormwater runoff have received increasing attention. Removal of these toxic particles is of paramount importance in regulating the quality of stormwater effluents. With the promulgation of the USEPAs Enhanced Surface Water Treatment Rule, a means for the removal of these particles in an efficient and rapid manner in treatment facilities is needed. This paper reviews the mechanisms and feasibility of a high rate sedimentation process in enhancing the settling in the flocculation‐sedimentation approach. The advantages of microcarriers, namely, to enhance particle capture as well as rapid sedimentation, are presented. A series of microcarrier‐jar tests was carried out. The experimental results reveal that the microcarrier process is effective in dramatically reducing treatment time and, in turn, reducing the size of treatment facility needed in a standard coagulation/flocculation unit operation.

Safe Separation Distances: Natural Gas Transmission Pipeline Incidents

The paper discusses a methodology to define safety implications of and damages that have resulted from gas transmission pipeline failures where fire and/or explosions have occurred. The records of the National Transportation Safety Board were examined to determine the area that was burned and/or impacted by a resulting explosion. The impacted area was then correlated with the physical parameters of the pipeline to see if a relationship existed. The parameters considered included the pipe diameter, the operating pressure at the point of release, the volume of material released, the maximum radius burned by the fire, the height of the flame and the maximum distance effected by the resulting explosion (if one occurred). Two strong correlations were found between the operating pressure in the pipe and the area burned in the incident for the two cases, with and without an explosion taking place. These results may be used to define a safe separation distance for a natural gas transmission pipeline.Copyright

Analysis Of Flow Reduction Factors For Storm-Water Management Regulations

Two watershed models were reviewed in this study on the utilization of flow reduction factors in detention basins. The watersheds were the Middle Brook and the Devils-Cedar Brook basins in New Jersey. A flow reduction factor set of 75%, 80%, 90 %, on average, was used in the Middle Brook Model with ultimate flow conditions reduced to a fraction of undeveloped conditions in the watershed. Similarly, a flow reduction factor set of 40%, 65%, 65% was used in the Devils-Cedar Brook Model with ultimate flows reduced to a fraction of existing conditions at the time of the study. A plot of ultimate to pre-ultimate flow ratios for sub-watersheds of the Middle and Devils Brooks vs. the change in impervious area from pre to ultimate conditions shows a strong correlation between the two factors. The greater the change in impervious area in the watershed, the greater the ratio of ultimate to pre-ultimate conditions. The difference in the required flow reduction factors for the two watersheds shows that each watershed will have a unique set of reduction factors to satisfy their specific design criteria.

Effectiveness of U.S. and International Pipeline Regulations With Regard to Land Use Planning

The transmission pipeline incident in Edison, New Jersey in March, 1994 raised public concerns about the safety of siting of transmission pipelines in proximity to populated areas. One of the responses to this incident was the issuance of a contract by the US Department of Transportation (USDOT) to the New Jersey Institute of Technology (NJIT) to study this and other issues with regard to pipeline safety. The basic findings were as follows: (1) the US Pipeline regulations are appropriate to minimizing risk while maintaining the viability of the pipeline industry; (2) all the regulations reviewed (i.e., US and international) approach the siting and regulation of pipelines in urban areas in a similar fashion; and (3) analysis of the USDOT incident database indicates that, in general, pipelines are sited in rural or underdeveloped areas, and damage resulting from an incident in highly developed areas is generally less than in rural areas due to the regulations restricting the allowable operating stresses in more densely populated areas.

MATHEMATICAL MODELLING & SIMULATION OF THE PASSAIC RIVER BASIN IN NEW JERSEY

Abstract A deterministic model was developed for a major water supply drainage basin in northern New Jersey, U.S.A. to predict the safe yield of the system under various operational scenarios. The basin is 800 square miles with five major water purveyors delivering water to several million people in northern New Jersey. The model operates on each individual purveyors infrastructure, as well as the entire basin as a whole, for sixty years of record. Included in the basin are ten reservoirs, four pump stations diverting water from the rivers to the reservoirs, and five system diversions. The model operates on reconstructed historical daily flow records at eleven stream locations in the basin. The model determines safe yields and it also predicts the return period of the drought of record for each purveyor system utilizing the Gumbel extreme value technique. The model may also be modified in the near future as an operational model to optimize the yield and cost of system delivery for the basin.