Joan U. Clarke, Dennis L. Brandon
U.S. Army Corps of Engineers Miscellaneous Paper D-96-2
Dredged sediment evaluations often require statistical analysis of chemical or biological test results. However, the resulting data are frequently problematic for standard statistical procedures because of improper experimental design, insufficient replication, failure to meet statistical test assumptions, outliers, and missing or below detection limit observations. Such nonideal data can seriously affect the error rates of statistical tests. This in turn increases the likelihood of drawing false inferences concerning the potential of a dredged sediment for adverse biological effects.
Simulations were conducted to investigate the impact of nonideal data on the performance of statistical tests recommended for dredged sediment evaluations.
Statistical test error rates were assessed using data that violated the normality and equality of variances assumptions, as well as data that included outliers or nondetects.
This report includes a brief introduction to statistical aspects of sediment sampling, some basic experimental designs and problems that can arise, errors in statistical testing and the importance of power, testing the normality and equality of variances assumptions and implications of violations, the effect of outliers, methods for analyzing less-than detection limit data and interpreting statistical test results. Program statements are provided for recommended statistical testing procedures using some popular statistical software packages. This report is intended as a companion to the statistics appendix of the Inland Testing Manual.
U.S. Army Corps of Engineers EM 1110-2-5025
31 July 2015
This Engineer Manual (EM) presents a comprehensive summary of the dredging equipment and dredged material placement techniques used by the U.S. Army Corps of
Engineers (USACE), and it describes the management and design processes associated with new work and maintenance dredging related to navigation projects. Guidance is provided on the following dredging topics:
- Evaluation and selection of dredging equipment for various materials to be dredged.
- Planning, designing, constructing, operating, and managing environmentally acceptable open-water and confined dredged material placement areas for both short- and long-term placement (disposal) needs.
- Planning, designing, developing, and managing dredged material for beneficial uses while incorporating ecological concepts and engineering designs with environmental, economical, and social feasibility.
Note: In this document, the terms “placement” and “disposal” are used synonymously to describe dredged material deposition after its removal from the dredging prism.
NAVFAC DM 38.2
This manual contains the following: information on procurement of dredging; types of equipment available, their characteristics and capacities; basic economics of dredging operations; and preparation of plans and specifications for the procurement of dredging for harbours, anchorages, turning basins and ship channels. A catalogue (description and characteristics) of dredges currently in the Navy inventory is included for guidance in the potential procurement of dredging by assignment of Navy equipment.