The Capitol Hill tunnel boring project is making quite a mess on the streets above, in the form of grey sludge. A manhole created for soil sampling on Boylston Ave and E. Pike St. spewed soil and soapy water onto the streets and on cars yesterday, leaving a grayish film on the surroundings. The mixture is used to soften clay soil for the drill. Those who ended up with dirty cars have been provided vouchers for car washes. For more info, see the full article here.