Section Env-Ws 382.24 - Alternate Minimum TOC Removal, Step 2 Requirements(a) A system owner using enhanced coagulation may submit to the department a written request for approval of alternative minimum TOC removal, Step 2, requirements.(b) The written request shall include:(2) The system EPA number; and(3) Results of bench-or pilot-scale testing.(c) The department shall use the bench-scale or pilot-scale testing results to determine the alternate enhanced coagulation level. For purposes of this section, "alternate enhanced coagulation level" means coagulation at a coagulant dose and pH as determined by the method described in (g) and (h) of this section such that an incremental addition of 10 mg/L of alum, as aluminum, or an equivalent amount of ferric salt, results in a TOC removal of less than or equal to 0.3 mg/ L.(d) The percent removal of TOC at the point determined in (c) above on the TOC removal versus coagulant dose curve shall be the minimum TOC removal required for the system.(e) This minimum requirement shall supersede the minimum TOC removal required by Table 382-3.(f) Failure to achieve department-set alternative minimum TOC removal levels shall be a violation of Env-Ws 300.(g) Bench- or pilot-scale testing of enhanced coagulation shall be conducted by using representative water samples and adding 10 mg/L increments of alum, as aluminum, or equivalent amounts of ferric salt, until the pH is reduced to a level less than or equal to the enhanced coagulation Step 2 target pH shown in Table 382-4 below: Table 382-4
ENHANCED COAGULATION STEP 2 TARGET pH
| Alkalinity (mg/L as CaCO3) | Target pH |
| 0-60 | 5.5 |
| 61-120 | 6.3 |
| 121-240 | 7.0 |
| >240 | 7.5 |
(h) For waters with alkalinities of less than 60 mg/L for which addition of small amounts of alum or equivalent addition of iron coagulant lowers the pH below 5.5 before significant TOC removal occurs, the system shall add necessary chemicals to maintain the pH between 5.3 and 5.7 in samples until the TOC removal of 0.3 mg/L per 10 mg/L alum added, as aluminum, or equivalent addition of iron coagulant, is reached.(i) The system owner may operate at any coagulant dose or pH necessary, consistent with Env-Ws 300, to achieve the minimum TOC percent removal under Env-Ws 382.23(i).(j) If the TOC removal is consistently less than 0.3 mg/L of TOC per 10 mg/L of incremental alum dose, as aluminum, at all dosages of alum, or equivalent addition of iron coagulant, the water shall be deemed to contain TOC not amenable to enhanced coagulation.(k) A system owner in (j) above, may submit to the department a written request for a waiver of enhanced coagulation requirements.(l) The written request shall include:(2) The system EPA number; and(3) The results of bench-test studies or pilot-test studies described in (g) and (h) above.(m) The department shall approve the waiver of enhanced coagulation requirements if the department determines that the water contains TOC not amenable to enhanced coagulation. For purposes of this section, "not amenable to enhanced coagulation" means that the TOC removal is reliably and consistently less than 0.3 mg/L of TOC per 10 mg/L of incremental alum dose at all dosages of alum.N.H. Code Admin. R. Env-Ws 382.24
(See third Revision Note at chapter heading Env-Ws 300); #7735, eff 8-2-02; amd by #8351, eff 5-14-05