Geology - Bullet Points

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4.1 Geology

  • Lancaster Co- characterized by weathered rock consisting of carbonate residuum-significant darst topography and relatively flat ground surface, streams not well developed into defined channels (4-4)
  • some rock removal may be required and will require blasting (4-9) 
  • potential impacts on water wells, springs, wetlands, nearby above-ground facilities and adjacent pipelines and utility lines could result from blasting (4-9)
  • Transco will offer both pre- and post-testing on water quality in wells within 150 feet of construction and would mitigate any damages (4-9) (how will landowners know of this offer?)
  • Transco would: use minimum charges, use blasting mats where necessary, use seismograph equipment to monitor, inspect aboveground and underground facilities within 150 ft, (what about 151 feet beyond?), provide occupants of nearby buildings 72 hours notice (what is nearby?).
  • CPL South (CPLS)- goes within 1/4 mile of 2 quarries, 13 coal mines, 65 abandoned mines (4-10)
  • CPLS crosses .6 miles characterized as High risk for subsidence, 1.2 miles at moderate relative risk, and 2.1 miles at low relative risk. (4-11)
  • Seismicity- 6-10 % chance of exeedance of CPLS within 50 year (4-12)
  • CPLS would cross the Martic Fault near MP 7.4 in Lancaster- These faults were, for the most part, healed during the meamorphism and not reactivated, but severely deformed later. (4-13)
  • On Flash floods: Flash floods are more common in Western US because soil is usually dry, sandy... Flash flooding is possible on waterbodies in project area. (4-19)
  • Karst Topography-would be crossed in CPLS- Transco developed a Karst Investigation and Mitigation Plan (4-22)
  • On Paleontological Resources- Transco developed a Discovery Plan- and EIs would be trained by project geologists to identify paleontological resources- We find the Discovery Plan to be acceptable (4-22)
  • The effect of the Atlantic Sunrise Project on Geologic resources would be minor.
  • The primary effect of construction on geologic resources would be disturbances to steep topographic features found along the construction right of way. (4-22)
  • The CPLS would cross an active railroad and adjacent to and active stone quarry near M-0183 MP 1.0. (4-23)
  • Pipelines located greater than 12 feet from a blast site are not usually susceptible to blast damage. (4-23)
  • We do not anticipate that the Project would be adversely affected by seismic activity due to the low probability and low incidence/susceptibility of significant magnitude earthquakes within the project area. (4-23)
  • Moreover, existing pipelines in the project area have not been adversely affected to date as a result of seismic activity, active faults or soil liquefaction. (4-23) (However, there has been no pipeline of this size and pressure in this area before)
  • To address concerns related to slope stability and construction on steep-side slopes, transo would implement BMPs to manage surface water and maintain slope stability including: minimizing potential for surface water ponding by removing direct surface water runoff, removing ponded water, and dewatering the trench, providing slope protection for falling rock on steep slopes containing boulders, removing unstable excavated material, compacting soft subsoils. (4-24)
  • Sinkholes- can occur during or following periods of severe drought, heavy precipitation, or spring snowmelt. Sinkhole development can affect permanent soil stabilization in the project area, resulting in erosion of soils and exposure of subsurface structures. Transco's mitigation measures: reduce potential for stormwater infiltration, eliminate soft ground or void features associated with geophysical anomalies, provide for long- term monitoring, design pipeline to span
  • sinkholes, minimize extent and time that open cut trench, reduce potential for surface water run on and ponding by directing surface water runoff, direct stormwater runoff, direct refueling activities, , provide for testing of wells. (4-24, 25) (and who keeps them accountable for all of these promises?)