In a rambling recently, I came across a phrase , "the Goose Creek-Edisto tunnels" and was filled with amazement that any one could have considered a car tunnel from Goose Creek South Carolina to Edisto Island South Carolina. A tunnel in the "low country" , a country filled with marshes and low lands. This just could not be.
This "rabbit trail" just had to be followed.
As it turns out, the story begins with the 1670 founding of Charleston and the need for shallow wells and rainwater cisterns to provide water for the inhabitants. The mineral rich ground water was preferred for household requirements while the more pleasant tasting rainwater was chosen for drinking.
In 1823, following techniques developed in London, the first auger drilled artesian well was commissioned and completed in 1825 at 1260 foot depth, yet producing poor results.
An artesian well uses the downward pressure of the weight of earth above an aquifer to create a pressure that lifts water to the surface. There are six main aquifers below ground in South Carolina. These are the Cape Fear, the Middendorf, the Black Creek, the Tertiary Sand, the Floridian and the Shallow Aquifer Systems.
In 1879 Charleston successfully drilled a 1970 foot deep well producing tremendously and meeting the needs of the population with additional wells until 1902 when more water was needed to support the city.
In 1904 an additional source, the Goose Creek reservoir was completed and provided additional "surface water" to support the growing demand.
Leveraging the knowledge of below ground conditions gleaned from the mining of hardened phosphate deposits in the late 1800s (see Blog item
Phosphate Mining ), it was decided in 1937 to drill a tunnel, a water tunnel, as a conduit for water from the Edisto River, 23 miles away, down to Charleston.
Creating the Tunnel
Inlet to The Edisto Water Tunnel
In this way the tunnel would serve to provide "gravity fed" surface water to the city. This tunnel was dug by hand and had required 9 years to complete.
In modern terminology, the loss of pressure in an aquifer is measured and referred to as "cones of depression". This is caused by the usage demands of artesian wells which drain the aquifer in an outreaching fashion. As aquifer water production declined and city usage increased in the early 1950s the Brushy Creek reservoir was constructed and later connected to the Goose Creek system by another seven miles of tunnel.
"Car tunnels" what was I thinking? Well I think I've cleared it up for myself.... now on to the next thing that may confuse me.
