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of municipal sewage sludge, what should be the concern about agricultural 

 or land application of these materials. In my view, following similar logic the 

 concern should be greater about land disposal. Why? Studies of digested sludge 

 discharge to the ocean through well-designed systems, such as for the City of 

 Los Angeles (a 7 mile 290 foot deep outfall), indicate that very little sludge 

 solids are found near the outfall site. Most of the solids are very fine particles 

 in the micron size range and are mixed and transported over large distances. 

 These solids settle slowly over large areas — theoretically and ultimately over a 

 major fraction of the ocean bottom. This area can be expected to be a substantial 

 fraction of the entire land surface; hence, the concentration of sludge solids 

 (grams/meter'') can be exi>ected to be very low. This neglects the continuous 

 covering of these solids by the normal oceanic sedimentation i)rocesses of which 

 the sewage sludge component is only a very minor part. In time as the result 

 of sediment deposition, a substantial portion of the sludge solids are removed 

 from contact with the water, biota, and ultimately, man. One can therefore 

 hypothesize that the ecological effects would be very minor. 



What happens if sludge disposal is practiced on agricultural land as advocated 

 strongly by the "organic farmer?" If the sludge contains appreciable toxicants, 

 these materials are concentrated in the surface mantle to a degree far greater 

 than in the ocean. This is due to the fact that the mass rate of application to 

 land surfaces (grams solids/meter^-year) is much greater than to the ocean 

 because of the very limited land area for agricultural application of sludge 

 solids — at least compared to the distribution on the ocean floor. Also agricul- 

 tural tillage practice retains the solids and toxicants (if any) in the surface 

 soil mantle where it has more direct contact with plants, animals, and ultimately 

 man, than in the ocean. Thus, which disposal method has least cost and minimal 

 ecological consequences and health risks? I contend that well-engineered digested 

 sewage sludge solids disposal to the ocean, including effective initial dispersion 

 of the solids has less ecological consequences and health risks than disposal 

 on land. From an ecological and cost standpoint, incineration and disposal of a 

 fraction of the problem to the atmosphere has not been considered and it isn't 

 considered seriously in California. 



Specification of a blanket waste treatment method policy for all coastal waste 

 dischargers poses a similar dilemma in achieving optimum benefits for each 

 doller spent for ecological improvement. The recent EPA requirement of second- 

 ary treatment for all waste discharges whether it be to the open ocean or Podunk 

 Creek poses real cost-consequence problems. As mentioned previously, essen- 

 tially all of the major Southern California waste dischargers employ today only 

 primary treatment with effective long deep outfall disi)ersion systems. Secondary 

 treatment is defined by EPA as 85 percent removal of biochemical oxygen demand 

 (BOD) or 30 mg/1 of BOD and suspended solids (SS) in the effluent, which- 

 ever is more restrictive. It is recognized that secondary treatment may also 

 increase slightly the removal of heavy metals and toxicants over that removed 

 by primary treatment ; however, the increased removal is minor and the cost is 

 great. Also, secondary treatment generally doubles the actual unit cost ( $/million 

 gallons treated) of primary treatment, and what are the benefits? As has been 

 demonstrated in Southern California practice, BOD (oxygen demand) and SS 

 (suspended solids) concentrations are not problems of consequence in well- 

 designed marine municipal waste disposal systems. This stems from the fact 

 that open ocean disposal accomplishes high dilution of the waste with ocean 

 water-dilution in excess of 100 to 1. This dilution results in concentrations of 

 these constituents in the ocean/wastewater mixture at the outlet equivalent to 

 removals of about 99 percent by treatment without dilution. Regretfully, the 

 secondary treatment, minimum dilution system was tried in California in the 

 early 19.50's. it failed, and the current reduced treatment-high dilution systems 

 were designed, built and have operated most satisfactorily to date as docu- 

 mented by the SCCWRP report (3). 



A possible and likely negative result from a blanket secondary treatment 

 requirement for all coastal cities is its impact on the development of regional 

 waste management systems. If all cities are required to have .'secondary treat- 

 ment regardless of receiving water conditions (including effective dilution on 

 water quality), what incentive will there be for a city located at the upstream 

 (head) of an estuary to move their secondary treated waste discharge location 

 downstream at added expense simply to increase the physical dilution of their 

 waste? Or similarly, why should a city transport its waste out of the estuary, 



