Chapter Seven   


The NRC's third point considers the:

(3)  effects on soils, crop production, and ground

The NRC report concluded the, "Treated municipal

wastewater effluent and sludge resemble normal

irrigation water and manures. Although they may contain

some exotic compounds and fertilizer elements in

different proportions than ideal fertilizer, they

present no significant hazard to agricultural soils,

crops, or the environment if they are applied in

quantities commensurate with crop needs." (p. 83)

If it is true that wastewater and sludge present no

hazard, why did NRC point out the potential hazards.

1.   "Organic matter in sludge and wastewater can impede

infiltration and aeration by temporarily plugging

the soil surface." (p. 69)

2.   "Following organic matter decomposition, trace

[pollutants] from wastewater and sewage are released

and form sparingly soluble reaction products. These

trace elements include arsenic, cadmium, copper,

cobalt, nickel, lead, selenite-selenium, molybdate-

molybdenum, and others.  Because of their sparingly

soluble nature and their limited
uptake by plants,

they tend to accumulate in the surface soil and

become part of the soil matrix (McGrath et al.,

1994). With repeated applications of wastewater,

and particularly with sludges, these elements could

accumulate to levels of toxic to plants (Chang et

al. 1992) and soil organisms (Mcgrath et al.,

1994). They could also accumulate in crops where

they could, in turn, build up to potentially

harmful levels in
humans, domestic animals, and

wildlife that consume the crops (Logan and Chaney,

1983)." (p. 70-71)

3.   "The accumulation of metals following long-term

applications of sewage sludge has been observed to

reduce levels of microbial biomass (Brookes et al.,

1986b) In a long-term field experiment that

compared sludge-amended soils to manure-amended

soils, (McGrath et al. (1994) reported microbial

biomass levels in the high metals sludge treated

soils to be approximately half of the manure-

treated soils." In effect, it is only half as good

as our ancestors fertilizer, even if there were no

hazardous substances in it.

4.   "Nitrate pollution of ground water is often

reported as an effect of excessive application of

conventional fertilizer to crops (Hallberg and

Keeney 1993)."

The EPA also reports that nitrates can build up in

cattle fodder to excessive levels, which will kill


The report also notes that, "Yield and crop quality

have been harmed by excess nitrogen in many crops,

including tomatoes, potatoes, citrus, and grapes (Bouwer

and Idelovitch, 1987)" (p. 66)

What will this do to humans who eat the produce?

Moreover, the NRC report found that: "The

application of
wastewater effluents to soil may pose

some risk of ground water contamination by viruses and

bacteria: however," they also noted, "that risk can be

minimized by adequate disinfection of reclaimed

wastewater and by slow infiltration rates." (p. 9)

Wastewater effluent is the cleanest treated water

from a treatment plant which normally is returned to the

rivers and lakes and yet the NRC report found that it

could contaminate the soil and ground water at a depth

of almost 100 feet.

Yet, some cities are now selling the effluent to

water lawns based on the premise that if it is clean

enough to return to our rivers and lakes, it is clean

enough to put on lawns.  However, according to Corpus

Christi Wastewater Superintendent Wayne Cockcroft, as

reported in the Corpus Christi Caller Times, "It's very

clean water that's suitable for outdoor use,"... "But

even when a lawn has been watered with effluent, we

encourage people not to let their children play on the

lawn until the water has soaked into the ground.  There

is always a chance that a child could get his hands wet,

put it in his mouth and get an
upset stomach."

If the NRC report found that 25 groups of both

viruses and bacteria in the effluent may contaminate the

ground water, what makes Cockcroft think the worse thing

that could happen to a child is an upset stomach?

And if the clean effluent could contaminate ground

water, why would the EPA allow "clean" sludge with

extremely high levels of toxic and hazardous substances

(3,000 ppm for chromium is an example) and 98 percent

water to be dumped within 30 feet of a lake or river?

Yet, the same sludge with less liquid can not be put in

part 503 landfill, because it may contaminate the

groundwater.  According to the EPA's preamble to the 503

regulation, "Sewage sludge with a high (in this case,

high is 600 ppm of Chromium) concentration of certain

organic or metal pollutants may pose human health

problems when disposed of in sludge only landfills

(often referred to as monofills) {part 503, surface

disposal}, or simply left on the land surface, if the

pollutants leach from the sludge into ground water.

Therefore the pollutant concentrations may need to be

limited or other measures such as impermeable liners

must be taken to ensure that ground water is not

contaminated." (FR. 58, 9259)

Furthermore, why didn't the NRC report question the

EPA for raising the pollutant limits for
lead from those

in the proposed part 503 of 300 ppm, the acceptable risk

level for children, to 840 ppm?  According to the NRC

the EPA risk assessment standards were the

primary purpose of the study.

Furthermore, the NRC report did not address what

will happen to crop safety when the land loading limits

are reached for any one of the pollutants in sludge.

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Review of National Academy of Science's (NAS) 1996 literary review report by
its National Research Council (NRC) Committee :

"Use of Reclaimed Water and  Sludge in Food Crop Production"