Geologic Mapping in Urban Settings


12 economic and environmental reasons why the geology of our cities must be mapped in detail:

  • Geologic materials provide foundation conditions that support our skylines. Evaluating their extent and favorable construction conditions has not been done.
  • Brownfield reclamation, redevelopment, and associated costs are dependent in significant part on the near-surface geology, which is poorly known.
  • The ground beneath our cities holds wastes, spills, and debris from generations of habitation, and many areas have been/plan to be redeveloped into parks, playgrounds, etc., and pose a real hazard. The subsurface geology, which controls the local movement of contaminants, has not been mapped.
  • Costs of excavation and fill, required for infrastructure, depend on the nature and thickness of glacial deposits and rock at construction sites and in nearby source areas where suitable fill can be obtained.
  • Development of underground space to quarry rock, tunnel for transportation or drainage control, or create warehouse space requires subsurface geologic knowledge.
  • Geology dictates where the highest quality, closest, and least expensive sand, gravel, and rock can be obtained for building and infrastructure upgrades. These resources are becoming depleted in areas closest to cities.
  • Occurrence and severity of hazards, such as building settlement, subsurface piping, flooding, and susceptibility to earthquake shaking, depend in large part on the nature and distribution of geologic deposits.
  • For those cities on a Great Lake, issues such as shoreline erosion, protection, and redevelopment strategies, sedimentation, beach replenishment, and near-shore lake bottom paving all require geologic understanding.
  • Suitability of land for preservation, restoration, or creation of open spaces, wetlands, and surface water bodies rely in part on the capability of geologic materials to successfully support the proposed use.
  • Cost and long-term performance of waste disposal sites rely on the geology.
  • Cost of containment/cleanup of contaminants rely in large part on the geology.
  • Ability of groundwater to recharge aquifers depends on variability of geologic materials and land use. Knowing where these materials occur would allow land-use planning to better coordinate efforts to increase recharge/decrease runoff.

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