18 SEWER DESIGN 



the city was $16,900, the different parts of the survey were 

 divided up into triangulation, n per cent; precise levelling, 

 1 6 per cent; topography, 36 per cent; and office work, 37 per 

 cent. The average cost in toto is given as $724.50 per square 

 mile, or $1.13 per acre.* 



In the Trans. Am. Soc. C.E., Vol. XXX, p. 611, are given 

 a number of instances of the cost of topographical surveys in 

 different parts of the world, most of them, however, covering 

 larger areas and using other methods than those required for 

 the survey of towns. A letter is quoted from Mr. J. C. Olmstead 

 to the effect that for the purposes of landscape architecture 

 the ordinary cost of suitable survey will range from $2.50 to 

 $20 per acre, being generally about $5 per acre. 



The following summary, Table I, is taken from an article t on 

 the cost of survey of a 4ooo-acre tract near Chicago, and is as 

 complete in all details as would be needed for any sewer-survey. 

 The article gives an admirable description of the various ele- 

 ments entering the cost and their effect upon the accuracy and 

 total cost of the survey. 



In connection with the New York State Canals, extensive 

 surveys were made in 1899, under the direction of the U. S. 

 Deep Waterways Commission. Along the Mohawk Valley 

 from Albany to Herkimer about 47,000 acres were surveyed 

 and mapped to a scale of 200 feet to an inch, with 2-foot con- 

 tours. The average cost was 86 cents per acre. A large amount 

 of detail was included, especially at the cities and villages along 

 the route. 



Borings were made by driving a casing and washing out the 

 material inside by forcing water down through a smaller 

 interior pipe. The average cost of 55,521 lineal feet of penetra- 

 tion, about 2 per cent being in river bottom, and the average 

 depth of hole being 29.5 feet, was 54 cents per vertical foot.J: 



* Jour. Ass'n Eng. Soc., Vol. XII, p. i. 

 t Trans. Ass'n Civ. Engrs. of Cornell University, 1898, p. 68. 

 I For detailed descriptions and costs of surveys in Croton Drainage Area, 

 see Engineering News, Vol. LXII, p. 428. 



