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@Tom
It’s a little disingenuous to suggest that your water bill will increase $50-100/month based solely on the presence of high rise buildings in the district.

From DC Water’s website, 600,000 DC residents and 1.6M residents of Maryland and Virginia are provided sewer service through DC Water’s collection system. As I suggested above, the cost of the project should be shared amongst the rate payers. If that were the case, you would be able to pay off the entire project in a year or two. That’s not even including the rates paid by commercial space for the 17.8 million annual visitors to the city within the city or the non-residents 700,000 who work in the city (DC Water’s #s).

Secondly, I’d love for a source that quantifies the amount of ground water you believed is being pumped into the system. Deep foundation structures are generally designed to limit ground water intrusion. Where ground water is high, these structures are typically placed on piles to prevent uplift from the ground water. The quantity of actual groundwater seeping into these structures is minimal compared to the overall capacity of the sewer system.

Now what you may refer to as “groundwater” might actually be stormwater collected off the impervious area of the building and that makes its way into underground parking structures via surface openings. This water would enter the sewer regardless of whether the structure is 100% above grade or it is pumped from a subgrade structure. In areas with high ground water, it is likely that more groundwater is infiltrating the sewer at joints in the sewer than being pumped into it from underground structures.

While I am not familiar with the exact depth of the water table throughout the city, I am confident assuming that the underground portion of a number of high rises are above the water table and aren’t subjected to any groundwater forces (namely areas of the city much higher than the river).

The real problem is stormwater. We can either pay to separate the storm and sanitary sewers (>>>>$2.6B) or we can pay for these tunnels and stop discharging our raw sewage into our rivers.

by jim on Jun 5, 2012 11:05 am • link • report