these metals is in the manner that yard waste is collected by
municipalities. Leaves collected at curbside by vacuum truck or
swept into trucks could also collect gutter debris laden with lead
and chromium from automobiles.

In contrast, significant levels of chromium and lead were not
detected in any of the monitoring wells at either Site A or B. This
suggests that the metals rapidly oxidize as they come into contact
with the atmosphere or they are attenuated by compounds in the soil
before they can leach into the ground water.

The results of pesticide sampling indicates that the potential for
pesticide contamination of ground water as the result of yard waste
composting is extremely low. Very low levels of atrazine were
detected in two wells at Site A and at none of the wells at Site B.
One impacted well at Site A was upgradient to the site and the other
well was a deep piezometer. This, added to the fact that atrazine is
typically only used by farmers under controlled conditions, would
indicate that the atrazine contamination probably originated from an
off-site source.

In the leachate analyses, only two samples, both from Site C, had any
measurable pesticide concentrations. One compound, 2,4-D, a very
common broadleaf herbicide used by homeowners, was found at a low
concentration of 1.8 ug/L. The ground water ES for this compound is
70 ug/L. Helfrich (1992) found similar levels of 2,4-D in yard waste
compost leachate. The other compound detected was a low level of

An interesting result of this study is that there appears to be a
definite correlation between the contaminant concentrations and the
level of anaerobic decomposition at a facility. Generally, the
lowest leachate compound concentrations were found at Site C (Table
4), where the wastes were occasionally moved and aerated. The
highest leachate compound values were found at Sites A and D (Tables
3 and 4), where the piles were seldom, if ever, turned and anaerobic
decomposition dominated.


There are definite, measurable impacts to ground water quality in the
form of elevated levels of nitrates, chloride and sometimes sulfate
at large, unlined yard waste compost sites where materials are
allowed to decompose anaerobically. These impacts can occur under
several different environments and with waste masses that range from
2000 yds3 to 15,000 yds3.

The leachate at these sites typically contain levels of chromium and
lead that exceed the Wisconsin ground Water quality standards, but
pesticide concentrations tend to be very low.    The leachate also
contains high levels of ammonia and total phosphorus that could be