Infiltration Response of Adsorbent Amended Filters for Stormwater Management under Freezing/Thawing Conditions

Abstract

Coastal cold climates experience frequent intermittent melting and freezing periods over the cold period. This intermittent freezing in stormwater systems affects the infiltration capacity and hence the performance. This paper investigates the infiltration capacity of engineered filter media (composed of sand mixed with charcoal, pine bark, or olivine) under freezing temperatures in a column-based laboratory setup. Infiltration into partially frozen filter media was replicated using a climate room. The filter media in the columns were brought to −2.5 • C, and water at +2 • C was percolated through the columns with a constant head of 5 cm. Infiltration performance was assessed by observing the time until breakthrough, and the infiltration rate 24 h after breakthrough. The results were compared to the observed hydraulic conductivity for the unfrozen filter media. A novel approach combining the unfrozen water content curves with X-ray tomographic (XRT) images of the materials was adopted to better understand the thermal and infiltration processes. Breakthrough was observed between ca. 21 and 56 h in all columns. The column with homogeneously mixed filter media with sand yielded the quickest breakthrough. The infiltration rates were higher than recommendations for infiltration-based systems in cold climates, making them a suitable option in cold climates.

In-Situ Monitoring and Characteristic Analysis of Freezing-Thawing Cycles in a Deep Vadose Zone

“…The freezing depth, defined as the depth with zero temperature, is often used to characterize the freeze-thaw process [9,26], as shown in Figure 10. According to the measured soil temperature and moisture data, the total freeze-thaw process, with the maximum freezing depth to be at a depth of 118 cm, lasted 112 days (from 19 November 2017, to 10 March 2018), and could be divided into three main stages: the initial freezing stage, the downward freezing stage, and the thawing stage.…”

The Modelling of Freezing Process in Saturated Soil Based on the Thermal-Hydro-Mechanical Multi-Physics Field Coupling Theory

“…Frozen soil is a dynamic system related to temperature, and the dynamic system involves heat transfer, material exchange, and soil deformation. Therefore, the structure, composition, and mechanical properties of frozen soils are more complicated than unfrozen soil [1,2]. The most important problem in permafrost engineering is frost heave, especially when the water content of soil is high.…”