-12- 



Town's share of this will be only five percent, or $1.15 per wet ton. The 

 Town's estimated cost per pile is itemized in Table 4. 



Although total cost of the system will be about $28.50 per wet ton, 

 spreading the cost across the State and United States tax bases means that 

 actual cost to the town is quite low. Obviously, the actual costs depend 

 upon location and conditions, so not every town could depend upon being 

 able to compost at this cost, nor upon receiving such a large percentage 

 of Federal and State Funds. Durham's costs will also increase over the 

 lifetime of the plant, since the largest variable cost is labor, which will 

 undoubtedly increase over the period. . 



Durham's plans for the new system include purchase of a wood chipper 

 with an automatic feed. This is felt to be a safer design, eliminating 

 the hazards encountered with the older chipper. This chipper should hold 

 the cost of wood chips to about $1.50 per yard. 



Finally, indications are that there might be a market for the screened 

 compost, and a nominal charge for the material might further decrease the 

 composting costs. This is particularly true if current University of New 

 Hampshire experiments using compost for production of turf and ornamentals 

 prove feasible on a commercial basis. 



IS COMPOSTING SAFE? 



The primary areas of concern associated with sludge composting are 

 heavy metal concentrations and the potential for pathogen survival. Both 

 of these areas have been the subject of much study in the past few years. 



The major subjects of concern amon^ the metals are cadmium, copper, 

 zinc, lead, nickel, chromium, and boron. Once such metals are added to 



