APPENDIX F 



SETTLING PONDS AND WASTEWATER TREATMENT 



WASTEWATER TREATMENT 



The Federa I -St ate effluent guidelines indicate that total suspended 

 solids (TSS) is the main effluent parameter that must be monitored during 

 mining and processing of construction sand and gravel (Hall and Kosakowski 

 1976). The present EPA requirement is that the TSS of a gravel mining effluent 

 should not exceed 50 mg/Jl at any time. In order to accomplish this final 

 concentration, a series of settling ponds and often a coagulant are normally 

 required. Specific needs will vary according to the amount of washing neces- 

 sary and the soil characteristics of the material. In a washing operation, 

 wash water can usually be recycled without need for discharge. In this case 

 the amount of settling required will depend on the need of the operator for 

 clean water. Generally, recycled water with a TSS of less than 200 mg/e, is 

 suitable for reuse. 



Specific details on how to design and operate settling ponds are dis- 

 cussed in Monroe (1973) and this document should be referenced if additional 

 information is needed. Following is a brief synopsis of his major recommenda- 

 t ions. 



Settling Ponds - pond with an outlet 



A. Used to clarify water for reuse or effluent discharge. 



B. Cross-sectional area of the pond must be large so horizontal velocity 

 is very slow. 



C. Water must enter pond over most of the width to make the entire pond 

 effective (e.g., to avoid short circuiting, channel formation). 



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