104 



DAVID G. CARGO 



complex. Althougli final evaluation is not 

 yet possible, we feel that the general result 

 of our efforts has been encouraging, 



I am indebted to many persons of this 

 and other institutions who have assisted us 

 in various ways during the designing and 

 installation of these systems. Particular 

 credit is due Dr. L. E. Cronin, Director of 

 the Natural Resources Institute, for his 

 efforts and perseverance in planning for 

 this invaluable and necessary tool for 

 research. 



THE WHARF SYSTEM 



The wharf system is a simple, straight- 

 through system utilizing plastic piping 

 and a hard-rubber centrifugal pump. 

 Flowing at 80 gallons per minute, the 

 water, after passing through the pump, 

 flows up a continuously rising supply pipe 

 provided with petcocks at frequent inter- 

 vals. This rising supply was designed to 

 insure that the pipe remains full despite 

 the level of use. This feature has been 

 found to be very efficient (fig. 1). 



The rather rapid flow through the sys- 

 tem forced us to provide the terminus with 

 a throttling-type valve to provide in- 

 creased pressure when needed. This valve 

 was required because, when a petcock was 

 opened, the rapid flow aspirated air into 

 the system instead of allowing water to 

 flow from the petcock. This valve induces 

 sufficient back pressure to overcome this 

 aspiratory tendency. We feel that this 

 valve is a necessary component. 



We have found that this system remains 

 virtually free of internal fouling of all 

 types except bacterial. During the warm 

 parts of the year, external fouling requires 

 a cleaning of the foot valve and strainer 

 every 10 days to 2 weeks. During the 

 colder periods of the year, this schedule 

 may be extended considerably. Our treat- 

 ment involves raising the intake head and 

 scraping and scrubbing the external foul- 

 ing. We then drain the line and flush it 

 thoroughly with hot (130° to 150° F.) 

 fresh water. This hot water is allowed 

 to remain in the line until it has cooled 

 (about 2 hours). The fresh water is then 

 pumped out after the head has been re- 

 turned to the normal pumping position in 

 the water. This schedule has been 

 markedly satisfactory throughout the 3 

 years of operation. Occasionally, the 

 motor of the pump is greased sparingly. 

 The pump has required no maintenance 

 or lubrication since installation. 



The main features of this system are in- 

 stalled in a special room which has been 

 designed for the handling of samples — 

 washing, sorting, holding, etc. Incor- 

 porated in the construction of the building 

 are underfloor drains, and future expan- 

 sion of the utility is provided by pipe car- 

 riers extended to the outside of the walls 

 so that this same system can be used to 

 supply outside tanks if needed at some 

 future date. 



intake 



"^ 



discharge 



(X 



foot valve 



centrifugal pump 



•priming valve 



Figure 1. — Wharf system. 



petcocks 



throttling valve 



