TABLE OF CONTENTS An existing secondary treatment plant located in the eastern United States treats an average daily flow rate of 250,000 gallons per day. The facility is required to upgrade to meet an effluent limitation of 10 mg/l BOD 5 and 10 mg/l suspended solids. The possibility of using existing facilities followed by spray irrigation is to be investigated. Based on a preliminary survey, four possible spray irrigation sites shown in Table 5.1 will be evaluated.
Describe a possible treatment scheme using spray irrigation.
Determine the land area required for the spray irrigation system.
Describe briefly the feasibility of using each site for spray irrigation based on the information provided.
| Potential Site No. | Land Area (acres) | Pumping Distance (feet) | Pumping Head (feet) | Dwellings Near Site | Average Ground Surface Slope |
|---|---|---|---|---|---|
| 1 | 150 | 1,000 | 120 | Several | 5 10% |
| 2 | 175 | 8,000 | 175 | Few | 5% |
| 3 | 200 | 15,000 | 110 | Few | 8 10% |
| 4 | 35 | 3,500 | 210 | Very Few | 10% |
| Potential Site No. | Type of Ground Cover | Existing Drainage | Soil Permeability |
|---|---|---|---|
| 1 | Woodland | Fair to Poor | Slow to Moderately Slow |
| 2 | Open Field | Good to Moderate | Moderately Rapid |
| 3 | Orchard and Open Field | Good to Moderate | Moderately Slow to Moderate |
| 4 | Open Field, Agriculture Use | Good | Moderate to Moderately Rapid |
A possible land application treatment scheme would include existing facilities, disinfection, holding pond, wastewater pumping and distribution capabilities, and spray irrigation site. A holding pond with a maximum 60 to 90 day detention time may be recommended in the eastern United States...
