Q1: The porosity of sediments in sewer pipes, is usually taken as

ANS:D - 0.013

A porosity value of 0.013 in the context of sediments in sewer pipes would imply that approximately 1.3% of the total volume of the sediment layer consists of void spaces or pores. In sewer systems, sediments can accumulate over time due to the deposition of solids carried by the wastewater flow. These sediments can occupy a portion of the cross-sectional area of the sewer pipe, thereby reducing its effective capacity for conveying wastewater. When engineers calculate the hydraulic capacity or flow characteristics of sewer pipes, they often account for the presence of sediments by considering their porosity. This porosity value indicates the fraction of the sediment layer that is comprised of void spaces. A porosity value of 0.013 suggests that for every unit of volume occupied by sediment, approximately 0.013 units of volume are empty space. In other words, the sediments are relatively dense, with a relatively small proportion of voids compared to their total volume. While porosity values for sediments in sewer pipes can vary depending on factors such as sediment composition, compaction, and deposition patterns, 0.013 would represent a relatively low porosity, indicating a denser sediment layer with fewer void spaces.