TABLE 2 Ten-Day Means of Laboratory Lead Concentrations in Submersible Pump Extractant(*) Pump Brand Mean of Mean of Mean of 30-Day and Model Days 1-10 Days 11-20 Days 21-30 Mean Grundfos 1.2 0.6 0.6 0.8 Myers 199.9 69.9 56.0 108.6 Aeromotor 761.5 310.1 290.3 453.9 Goulds 1501.3 368.0 444.6 771.0 Sta-Rite 1348.6 314.7 245.5 636.3 * Lead concentrations in [[micro]gram]/L
The wells fitted with the Aeromotor and Goulds pumps showed somewhat lower pH, hardness, conductivity, and alkalinity than the other three wells, although these differences were considered too minor to have a significant effect on the lead-leaching results.
TABLE 4 Comparison of Mean Overnight Dwell Times for Field and Laboratory Data, Adjusted by Dilution Factors(*) Days 1-10 Days 11-20 Days 21-30 Laboratory Fld Laboratory Fld Laboratory Fld 18X 75X 18X 75X 18X 75X Sta-Rite 75 18 3.1 18 4.2 2.8 14 3.3 1.2 Goulds 83 20 7.6 21 4.9 4.6 25 5.9 3.8 Aeromotor 42 10 11 17 4.1 6.8 16 3.9 4.7 * Lead concentrations in [[micro]gram]/L.
Only the Sta-Rite, Aeromotor, and Goulds pump results are shown, because the other two pumps exhibited essentially undetectable lead concentrations.
Of the three leaded-brass models, the field studies showed more rapid and continued concentration decreases over time for the Sta-Rite and Goulds models than for the Aeromotor pump, which, over the extended field usage period, appeared to stabilize at overnight dwell concentrations of approximately 3 [[micro]gram]/L.