In recent years, urban planners in Southgate have advocated for replacing traditional asphalt roads with permeable paver blocks. Proponents claim that this transition will dramatically reduce urban runoff by allowing rainwater to filter directly into subsurface aquifers, thereby preventing seasonal street flooding. Their argument relies on pilot study data demonstrating that newly installed permeable pavers absorb up to eighty percent of surface water. Based on these findings, the city council recently approved a major capital project to pave all high-traffic downtown avenues with permeable blocks.
However, environmental engineer Dr. Aris Thorne argues that this initiative will not achieve its intended flood mitigation goals. Thorne points out that permeable pavers require specialized high-pressure vacuuming every three months to clear fine sediment from the gaps; otherwise, silt accumulation reduces water infiltration to the level of standard asphalt within eighteen months. Because Southgate's public works department currently possesses only conventional street sweepers and lacks the budgetary funds to purchase specialized vacuuming machinery, Thorne concludes that the new paving project will ultimately fail to alleviate downtown flooding.
Dr. Thorne's conclusion that the project will fail to alleviate downtown flooding depends on which of the following unstated assumptions?
- Southgate's public works department cannot maintain the pavers' permeability through alternative equipment or non-budgetary service arrangements.Answer
- BPermeable paver blocks lose most of their water absorption capacity within eighteen months if left uncleaned.
- CDowntown Southgate experiences significantly heavier seasonal rainstorms than neighboring municipal districts.
- DConventional street sweepers cause structural damage to the interlocking joints of permeable paver blocks.