Megan from Eastern Village brought this to our attention on the Yahoo! Group this afternoon:

In case you live in the neighborhood but not in one of the buildings that were formally notified: the construction project adjacent to the Giant supermarket has hired Air Power Inc (contact: Clifford Leiter, 703-471-4071) to blast every workday at 2 p.m. for approximately 4 months. This is to remove the bedrock under the site to build their underground parking garage. (The project adjacent to MICA chose to
jackhammer it away instead, and it has taken nearly a year of 40+ hrs/wk jackhammering -- you may have noticed this lovely sound. So I suppose one explosive blast per day is better...)

Here are the warning air horns they will sound:

• 15 min warning - one long horn sound
• 5 min warning - three short horn blasts
• Blast Signal - five short horn blasts; an explosion (lasting two seconds) will occur within one minute
• All-Clear - one long horn sound

I am just summarizing what was handed out to the residents at Mica; I don't have any inside info. (I live at EVC, and I'm a little annoyed they didn't bother to formally notify us, because it's a pretty startling thing to hear/feel, even a block away!)