7 Del. Admin. Code § 7103-68.0
Current through Register Vol. 28, No. 4, October 1, 2024
Section 7103-68.0 - Table 303-1 Assessment Criteria For Inorganic Constituents in WasteWater Applied to Land (U.S. EPA, 1976 and 1981)68.1| Potential Problem and Constituent | No Problem | Increasing Problem | Severe |
| pH (std. units) | 5.5 - 8.4 | | <5.0 <9.0 |
| Sodium Adsorption Ratioa | < 5.0 | 5.0-9.0 | > 9.0 |
| Electrical Conductivityb (mmho/cm @ 25oC) | < 2-4 | 4-8 | 8->12 |
| Bicarbonate (meq/L) (mg/L as CaCO3) | 1.5 < 150 | 1.5-8.5 150-850 | >8.54 > 850 |
| Chloride (meq/L) (mg/L) | < 3.0 < 100 | > 3.0 > 100 | > 10 > 350 |
| Fluoride (mg/L) | < 1.8 | | |
| Ammonia (mg/L as N) | > 5.0 | 5.0 - 30 | > 30 |
| Sodium (meq/L) (mg/L) | <3.0 <70 | >3.0 >70 | 9.0 210 |
| Trace Metals (mg/L): | | | |
| Aluinum | <10 | | |
| Arsenic | <0.2 | | |
| Beryllium | <0.2 | | |
| Boron | <0.5 | 0.5-2.0 | >2.0 |
| Cadmium | <0.02 | | |
| Chromium | <0.2 | | |
| Cobalt | <0.1 | | |
| Copper | <0.4 | | |
| Iron | <10 | | |
| Lead | <10 | | |
| Lithium | <2.5 | | |
| Manganese | <0.4 | | |
| Molybdenum | <0.02 | | |
| Nickel | <0.4 | | |
| Selenium | <0.04 | | |
| Zinc | <4.0 | | |
aSodium Adsorption Ratio - Na+1
SQR [(Ca+2+ Mg+2)/2 ]
Where, Na+1 Ca+2 and Mg+2 in the wastewater are expressed in milliequivalents per liter (meq/L). SQR represents 'square root of'.
bSeverity of problem related to salt tolerance of the crop.
68.2 Values of saturated vertical hydraulic conductivity must be modified by an appropriate safety factor to determine design percolation. The safety factor reflects the influence of several elements including: the fact that long periods of saturation are undesirable, the uncertainty of test values, the drainage characteristics of the land treatment site, the variation of permeability within and between different soil series, the rooting habits of the vegetation, soil reaeration factors, and potential long- term changes in soil permeability due to wastewater application.68.3 The Department requires that the design percolation rate at land treatment sites with seasonal high groundwater at depths greater than 5 feet (after consideration of mounding due to wastewater irrigation(c) be no more than 10 percent of the mean saturated hydraulic conductivity of the most limiting layer within the first five feet from the surface. Sites with seasonal high groundwater less than 5 feet deep shall be evaluated as to need for the drainage improvements before they are utilized for slow rate land treatment. The design percolation at such sites is a function of the design of the drainage system and the hydraulic conductivity of the most limiting layer above the drain depth.68.4 The percentage reduction in mean hydraulic conductivity to specify the design percolation rate should be reduced for variable or poorly defined soil conditions. The percentage to be used is a judgement made by the designer after consideration of all site physical, climate, and vegetation management factors. Refer to the EPA Process Design Manual (EPA 1981) for additional discussion of design percolation rate selection.7 Del. Admin. Code § 7103-68.0