Tour of Village WWTF Facilities
1/3/08
Andy Perchlik
Rich Phillips
Wastewater Facilities--- Jim Brimblecomb for Earth Tech—Plant built 1980
The facility includes:
1) Two submersible 5 HP grinder pumps which rotate automatically each time pumping is called for by the filling of the wet well
2) The pumps lift the wastewater into the two aerated lagoons where mixing, biological treatment and settling are provided. The necessary air for mixing and treatment is provided by two 7.5 HP air blowers which alternate in use on a manual basis.
3) The treated wastewater flows through a chlorination chamber where a chlorine solution is added by a very small pump after which the flow is measured and discharged to the Winooski.
4) The buildings include an unheated wood frame storage garage with an attached blower room and a heated concrete block with brick facing control building.
5) The control building is 18’X29’ with a 9’x7’ corner where the roof extends but there are no sidewalls in this area which covers over the chlorine contact chamber built below grade in the corner.
6) The enclosed part of the control building includes a very small 8’x8’office, a 7’x7’ bathroom, a 7’x8’ chorine feed room, 16’x11’ original blower room now used for storage. Four ceiling-hung electric units heat the control building. The temperature is kept very low in the chorination room and blower room and quite low in the office and bathroom.
7) A 30-gallon electric hot water heater provides hot water. Hot water is normally only used for hand washing.
8) There are six two tube fluorescent light fixtures from 1980 (T12) that will be less efficient that current T8 based units.
9) The outside walls of the control room consist of an inner wall of 8inch concrete blocks with 1.5 inches of insulation board, a 1-inch air space and a 4-inch brick. The plans are unclearly as to the depth of insulation above the ceiling, but snow doesn’t appear to melt off the roof too quickly.
Possibilities:
1) In this case the hot water demand is very low so a net power savings likely would result from conversion to on-demand water heating devise rather than heating a lot of water only to let it cool in the 30-gallon tank and then require reheating. Jim has such an on-demand heater that could be installed under the sink in the office for hand washing. He would plumb it in so that the existing water heater can be bypassed for hand washing but turned back on if there was a need for taking showers such as when the lagoons are to be cleaned (dirty work). We suggested this change be made but Jim should consult the Trustees.
2) The influent pumps are original but have been refurbished in the last few years so there probably is little more that can be done to save energy here. The pumps are a 27-year-old design however, so we will check to see if newer designs are more efficient and, if so, what the payback would be.
3) The blowers have been replaced and moved to the storage building in the recent past and the aeration system in the lagoons also has been replaced. The backpressure was reduced with the new aeration system and slower speed blowers were compatible and were purchased. There is likely no economical improvement to be made in this system. However, we suggest looking into the possibility of reducing the speed and output of the blowers during some of the winter when less air may be needed to meet the treatment process. This will need consultation with DEC- WWMD- O&M to decide how much, if any, reduction in speed/output may be allowable. Jim does not want to address this possibility until after the lagoons have been cleaned which makes sense.
Since there are few options to reduce energy use at this plant we think this blower speed reduction possibility should definitely be evaluated.
4) We will look into the economics of changing out the lighting fixtures but their very limited use makes that an unlikely recommendation.
5) Efficiency Vermont did a quick evaluation of changing out the electric heat for LPG. We will look at this again. Similar to the lights with the very minimal heating actually being used, we need to look close at the benefit. We will look into the heat losses expected through the brick and block walls. If it is substantial, the possibility of inside insulation might be reviewed.
6) We will study all the information to determine if there are other possibilities.
Needed from Jim
The manufacturer, model, size, horsepower and amp draw of the submersible influent pumps
The backpressure and the actual amp draw at the blowers.
Borrowed from Jim
One set of plans