68 



TYPE D 



Ihitreated piles encased in reinforced concrete, deposited inside a 

 wooden cylinder, first c<5st SI. 85 per square foot 



Interest on investment, at 5% SO . 0925 



Maintenance, at 1% 0.0185 



Insurance 



Sinking fund payment . 0387 



Depreciation reserve . 0445 



Loss of revenue . 0063 



Total annual cost per square foot 5>0 . 2005 



TYPE E 



Untreated piles surrounded by pre-cast reinforced shells driven 

 into the bottom, first cost S2.25 per square foot 



Interest on investment, at 5% SO . 1 125 



Maintenance, at 1% 0.0225 



Insurance 



Sinking fund payment 0.0471 



Depreciation reserve . 0542 



Loss of revenue . 0063 



Total annual cost per square foot SO . 2426 



TYPE F 



Untreated piles encased in plain concrete poured above water and lowered into place, 



first cost SI -40 per square foot. (Derived from the cost of a creosoted pile pier by 



deducting the difference in cost of creosoted and untreated piles and adding the cost 



of the concrete protection, assumed at 60 per cent of the present price.) 



Interest on investment, at 5% SO. 0700 



Maintenance, at 3% 0. 0420 



Insurance 



Sinking fund payment . 0293 



Depreciation reserve . 3373 



Loss of revenue . 0063 



Total annual cost per square foot SO . 1813 



LIFE OF DIFFERENT TYPES FOR EQUAL ANNUAL COST 



Annual cost of T>-pe A, SO. 1568 per square foot 

 Life assumed for Type A, 25 years 



TYPE B 



Maintenance and interest SO . 1200 



Annual payments, reserve funds . 0368 



Required at end of life: 



Sinking fund 2 . 0000 



Depreciation reserve 2 . 4000 



Loss of re\enue . 3000 



Total required $4 . 7000 



Life necessary to produce this sum at S*-}, 41.0 years. 



