in the experimental installation of reinforced concrete sills and abut- 

 ments in Carp Creek (Unit 2). Had this additional construction been 

 omitted, reinstallation costs would have been approximately $1,000. 



The figures presented above are broken down in Table 13 where 

 they are presented by operational units. An operational un.t is any 

 weir and trap or group of such structures which, when geography and 

 work load are considered can be most economically and efficiently oper- 

 ated by a single crew of men. Unit crews consist of night and day 

 shifts of one to four men per shift depending on the season aid the size 

 of the unit. 



The expenditures indicated here for individual operational units 

 are believed to be representative of the costs of installing and operat- 

 ing such units (comprised of one or more mechnical control devices) 

 in any other similar areas in the Lake Huron and Lake Michigan basins. 

 Gross costs in other unit geographic areas such as Control Zone H-1 

 will vaiy widely from the costs indicated for that Zone depending on 

 the number of large, permanent- type weirs and traps required, the extent 

 of the area (control zone), and the dispersion of all required control 

 structures within the area. Operating unit costs in Control Zone H-1 

 will not apply, for example, in the Lake Superior basin where the 

 accessibility of most streams requiring control devices is very poor. 

 No data are available concerning installation and operating costs in 

 streams in the more remote and wild areas bordering on that lake. 



Figure 5. --Portable -type weir and trap in Carp Creek, 

 Presque Isle County, Mich. , after installa- 

 tion of permanent sills, trap base, and 

 abutments of concrete. 



34 



