CELPIP Reading Part 3Reading for Information Practice

A. Conventional pavement sends rain toward drains because its continuous surface admits almost no water. Permeable pavement carries vehicles or pedestrians while allowing rainfall to pass through openings in the surface. Systems may use porous concrete, porous asphalt, or solid blocks separated by joints filled with small aggregate. The correct choice depends on expected loads, climate, maintenance, and the soil lying beneath the installation. Viewed together, details about the runoff problem and permeable surface idea connect visible characteristics with processes that are less immediately obvious to an ordinary observer at first.

B. Water enters through pores or joints and reaches a bed of clean, open-graded stone below. Spaces between the stones temporarily store runoff that cannot immediately soak into underlying ground. A fabric or carefully graded layer may separate the reservoir from soil without blocking water movement. An underdrain can release stored water slowly where natural infiltration is limited or groundwater needs protection. Within structure and maintenance of permeable pavement, the result is a system in which structure, timing, and local conditions remain closely connected throughout continuing development.

C. Temporary storage reduces the peak flow reaching nearby pipes during an ordinary storm. Filtering through surface aggregate and soil can also remove some particles carried from the pavement. However, sites with unstable ground, heavy contamination, or very high traffic may require another approach. Designers must consider winter freezing because trapped water and unsuitable materials can damage the structure. Observations of infiltration benefits and site constraints show why the same process may appear somewhat different from one site to another as surrounding conditions continue to change.

D. Fine sediment gradually fills surface openings if runoff from bare soil reaches the pavement. Vacuum sweeping or specialized cleaning removes accumulated material more effectively than simply washing it deeper. Sand used for winter traction can cause rapid clogging unless maintenance accounts for the extra particles. Inspection after construction confirms that surrounding landscaping does not direct muddy water onto the finished surface. Understanding structure and maintenance of permeable pavement therefore requires attention to both immediate effects and slower forms of change within the whole connected system.

E. Not given in any of the above paragraphs.