In my previous post “We have met the enemy and he is us“, I discussed the “dewatering system” that was built for the new Marriott Hotel in downtown Indianapolis and the impact this system will have on the Combined Sewer Overflow system. Today, let’s examine some of the other impacts this system and others like it have on our environment.
John Muir once said “When one tugs at a single thing in nature, he finds it attached to the rest of the world.” What this means is all of the systems in nature are interrelated and changes in one area can have dramatic impacts in others, in other words, when we try to outsmart nature, we inevitably screw something else up! This “dewatering system” is an excellent example; there are impacts, not only to the water systems, but also to energy, carbon emissions, human health and wildlife survival.
Water – Forget the fact that these pumps are taking what could be perfectly good drinking water (or at the very least perfectly good “process” water) and flushing it down the drain, there are other impacts to the water systems. Because the parking garage in this example was built below the water table, pumps run continuously to pump the naturally occurring groundwater into the sewer system. The effect of this pumping is to lower the water table in the area, and potentially in a large surrounding area. When the water table is lowered several things occur. First, anyone in the area that is using well water will find that their wells go dry as the water table lowers, thus requiring them to dig their wells deeper, sometimes at great expense. Next, as the water table lowers, water, being water, will follow the path of least resistance and begin to “fill in” the area. This means groundwater from a larger area will begin to move thus impacting larger and large areas. In some cases, nearby wetlands and rivers could begin to drain and dry up.
In addition, as the water table lowers, plant life that is dependent upon that water will begin to die out as its root system can no longer reach its water source. This may require additional irrigation to keep the plants alive which adds to the vicious cycle and strain on the water system. In some cases, invasive plants will migrate into the spaces left behind by the dying plants. Wildlife that depends on the native plants will die out or migrate to other areas due to lack of food.
Among the impact caused by lowering the water table is subsidence. Because the presence of ground water creates hydraulic pressure, it is able to support the weight of the soil, rock, AND BUILDINGS above it. Removing the groundwater will cause a “sinking” or settling of the earth above it. Don’t believe me? The city of San Jose is THIRTEEN feet lower today than it was 100 years ago. The problems in New Orleans were exacerbated in part by subsidence caused by the extraction of groundwater over the last century. What will be the impact to the buildings as the ground around them SINKS? They too will sink and settle causing foundation problems, and other structural and non-structural issues throughout the building or HOME!
River – While we are talking about water, let’s look at the impact on the river. According to the senior manager on the project for Marriott, the water was going to the river any way, well was it? Ground water is replenished by rain water, surface water, AND NEARBY RIVERS AND STREAMS. This water may have COME from the river not be on its way TO the river. As the water table lowers, the river could try harder and harder to refill the void, eventually drying up the river. It has happened before folks! However, let’s assume for the moment that the manager was right and the water was heading to the river. By “speeding up the process” the ecosystem of the river will be changed. Rather than the water slowly filtering through the ground (and being naturally cleaned and filtered along the way) it will be blasted into the river. This will lead to increased erosion as the water speed is faster than is natural. The increase in erosion will lead to additional sediment in the water (already the number one pollutant in Indiana). This increase in sediment will begin to kill off the fish and plant life in the river as they can no longer find food or the food dies off because of lack of sunlight that is now blocked by the sediment. In addition, many of the organisms that serve a key role in the food chain are impacted by even slight changes in water temperature. Because this water did not reach the river naturally, it will change the temperature of the water.
Energy – What a minute, I thought we were talking about water here, what does that have to do with energy? In my next post we will discuss the energy impacts (both direct and indirect) of the “dewatering systems”.