How will the testing laboratories handle the new 24-hour MassDEP requirements under Tier 1?
PWS should educate their laboratories about the new requirements. However, the requirement is for PWS to issue PN no later than 24 hours after learning of a violation. Certified laboratories are required under 310 CMR 42.13(4) to notify their clients of the results of all samples that exceed any established MCLs or reportable concentrations within 24 hours of obtaining valid data. Due to the range of acceptable holding times (the time between collection and analysis) and the time necessary to validate results, the total timeline between sample collection and the public notification (PN) may exceed 24 hours. When a threat to public health is suspected, PWS should request rush analytical services. MassDEP will take this matter under advisement and notify PWS and certified labs on any further clarifications.
