NR 252.0365(3)(a)1.
1. The concentration value that corresponds to an instrument signal or noise ratio in the range of 2.5 to 5. If the criteria for qualitative identification of the analyte is based upon pattern recognition techniques, the least abundant signal necessary to achieve identification shall be considered in making the estimate.
NR 252.0365(3)(a)2.
2. The concentration value that corresponds to 3 times the standard deviation of replicate instrumental measurements for the analyte in reagent water.
NR 252.0365(3)(a)3.
3. The concentration value that corresponds to the region of the standard curve where there is a significant change in sensitivity at low analyte concentrations, such as a break in the slope of the standard curve.
NR 252.0365(3)(a)4.
4. The concentration value that corresponds to known instrumental limitations.
NR 252.0365(3)(b)
(b) Prepare reagent or blank water that is as free of analyte as possible. Reagent or interference free water is defined as a water sample in which analyte and interferent concentrations are not detected at the method detection limit of each analyte of interest. Interferences are defined as systematic errors in the measured analytical signal of an established procedure caused by the presence of interfering species or interferent. The interferent concentration is presupposed to be normally distributed in representative samples of a given matrix.
NR 252.0365(3)(c)1.1. If the MDL is to be determined in reagent or blank water, prepare a laboratory standard such as an analyte in reagent water at a concentration which is at least equal to or in the same concentration range as the estimated MDL. It is recommended to be between one and 5 times the estimated MDL. Proceed to
par. (d).
NR 252.0365(3)(c)2.
2. If the MDL is to be determined in another sample matrix, analyze the sample. If the measured level of the analyte is in the recommended range of one to 5 times the estimated MDL, proceed to
par. (d).
NR 252.0365(3)(c)3.
3. If the measured concentration of analyte is less than the estimated MDL, add a known amount of analyte to bring the concentration of analyte to between one and 5 times the MDL. In the case where an interference is coanalyzed with the analyte and the measured level of analyte is greater than 5 times the estimated MDL, there are 2 options:
NR 252.0365(3)(c)3.b.
b. The sample may be used as is for determining the MDL if the analyte level does not exceed 10 times the MDL of the analyte in reagent water. The variance of the analytical method changes as the analyte concentration increases from the MDL, hence the MDL determined under these circumstances may not truly reflect method variance at lower analyte concentrations.
NR 252.0365(3)(d)1.1. Take a minimum of 7 aliquots of the sample to be used to calculate the MDL and process each through the entire analytical method. Make all computations according to the defined method with final results in the method reporting units. If blank measurements are required to calculate the measured level of analyte, obtain separate blank measurements for each sample aliquot analyzed. The average blank measurement is subtracted from the respective sample measurements.
NR 252.0365(3)(d)2.
2. It may be economically and technically desirable to evaluate the estimated MDL before proceeding with
subd.1. This will prevent repeating this entire procedure when the costs of analyses are high and insure that the procedure is being conducted at the correct concentration. It is quite possible that an incorrect MDL can be calculated from data obtained at many times the real MDL even though the background concentration of analyte is less than 5 times the calculated MDL. To insure that the estimate of the MDL is a good estimate, it is necessary to determine that a lower concentration of analyte will not result in a significantly lower MDL. Take 2 aliquots of the sample to be used to calculate the MDL and process each through the entire method, including blank measurements as described in
subd.1. Evaluate these data:
NR 252.0365(3)(d)2.a.
a. If these measurements indicate the sample is in the desirable range for determining the MDL, take 5 additional aliquots and proceed. Use all 7 measurements to calculate the MDL.
NR 252.0365(3)(d)2.b.
b. If these measurements indicate the sample is not in the correct range, reestimate the MDL, obtain new sample as in
par. (c) and repeat either
subd.1. or
2.
NR 252.0365(3)(e)
(e) Calculate the variance (S
2) and standard deviation (S) of the replicate measurements, as follows:
n n
S2 = 1 [S xi2 - (
S xi)2/n
n-1 i=1 i=1
s+(s2) 0.5
where: the xi, i = 1 to n are the analytical results in the final method reporting units obtained from the n sample aliquots and
n
S xi2
i=1
refers to the sum of the X values from i = 1 to n.
MDL = t(n-1, 1-a = .99) (S)
where:
MDL=the method detection
t (n-1, 1-a=.99)=the students' t value appropriate for a 99% confidence level and a standard deviation estimate with n-1 degrees of freedom as given in subd. 2.
S=standard deviation of the replicate analyses.
NR 252.0365(3)(f)2.
2. The 95% confidence limits for the MDL derived in
subd. 1. are computed according to the following equations derived from percentiles of the chi square over degrees of freedom distribution (X2/df) and calculated as follows:
MDLLCL=0.69 MDL
MDLUCL=1.92 MDL where MDLLCL and MDLUCL are the lower and upper 95% confidence limits respectively based on 7 aliquots.
NR 252.0365(3)(g)1.1. Optional iterative procedure to verify the reasonableness of the estimated MDL and calculated MDL of subsequent MDL determinations.
NR 252.0365(3)(g)2.
2. If this is the initial attempt to compute MDL based on the estimated MDL in
par. (a), take the MDL as calculated in
par. (f), spike in the matrix at the calculated MDL and proceed through the procedure starting with
par. (d)1.
NR 252.0365(3)(g)3.
3. If the current MDL determination is an iteration of the MDL procedure for which the spiking level does not permit qualitative identification, report the MDL as that concentration between the current spike level and the previous spike level which allows qualitative identification.
NR 252.0365(3)(g)4.
4. If the current MDL determination is an iteration of the MDL procedure and the spiking level allows qualitative identification, use S
2 from the current MDL calculation and S
2 from the previous MDL calculation to compute the F ratio.
if S2
A < 3.05
S2B
then compute the spooled standard deviation by the following equation:
spooled = [ 6SA2+ 6SB
2 ]0.5
____________
12
if S2
A > 3.05
S2B
respike at the last calculated MDL and process the samples through the procedure starting with par. (d).
NR 252.0365(3)(g)5.
5. Use the
Spooled as calculated in
subd. 3. to compute the final MDL according to the following equation:
MDL=2.681 (Spooled)
where 2.681 is equal to t (12, 1-a=.99)
NR 252.0365(3)(g)6.
6. The 95% confidence limits for MDL derived in
subd. 4. are computed according to the following equations derived from percentiles of the chi squared over degrees of freedom distribution.
MDLLCL=0.72 MDL
MDLUCL=1.65 MDL
where LCL and UCL are the lower and upper 95% confidence limits respectively based on 14 aliquots.
NR 252.0365(4)
(4) Reporting. The analytical method used shall be specifically identified by number or title and the MDL for each analyte expressed in the appropriate method reporting units. If the analytical method permits options which affect the method detection limit, these conditions shall be specified with the MDL value. The sample matrix used to determine the MDL shall also be identified with the MDL value. Report the mean analyte level with the MDL. If a laboratory standard or a sample that contained a known amount analyte was used for this determination, report the mean recovery and indicate if the MDL determination was iterated. If the level of the analyte in the sample matrix exceeds 10 times the MDL of the analyte in reagent water, do not report a value for the MDL.
NR 252.0365(5)
(5) Reference. Glaser, J.A., Foerst, D.L., McKee, G.D., Quave, S.A., and Budde, W.L., “Trace Analysis for Wastewaters," Environmental Science and Technology, 15, 1426 (1981).
NR 252.0365 History
History: Cr. Register, May, 2001, No. 545, eff. 6-1-01. NR 252.04
NR 252.04 Applicability of sulfide pretreatment standards. NR 252.04(1)(1) A POTW receiving wastewater from a facility subject to this chapter may require more stringent pretreatment standards for sulfide than those established by this chapter without EPA approval.
NR 252.04(2)
(2) The pretreatment standards for sulfide established by this chapter will not apply if the POTW receiving wastewater from a facility subject to this chapter certifies in writing with explanation of relevant factors considered, in accordance with the provisions of
sub. (3) that the discharge of sulfide from the facility does not interfere with the operation of the POTW. In making this determination, the POTW shall consider all relevant factors including but not limited to the following:
NR 252.04(2)(a)
(a) The presence and characteristics of other industrial wastewaters which can increase or decrease sulfide concentrations, pH, or both.
NR 252.04(2)(b)
(b) The characteristics of the sewer/interceptor collection system which either minimize or enhance opportunities for release of hydrogen sulfide gas.
NR 252.04(2)(c)
(c) The characteristics of the receiving POTW's headworks, preliminary and primary treatment systems, and sludge holding and dewatering facilities which either minimize or enhance opportunities for release of hydrogen sulfide gas.
NR 252.04(3)(a)(a) On October 13, 1983, a POTW which intends to certify that the sulfide pretreatment standard does not apply shall publish, in a local newspaper with the largest circulation, a notice that presents the findings supporting this determination consistent with
sub. (1). Allowance for public hearing of these findings shall be provided. The POTW shall identify all existing facilities to which the sulfide pretreatment standard otherwise established by this chapter would not apply.
NR 252.04(3)(b)
(b) On January 11, 1984, a POTW which intends to certify that the sulfide pretreatment standard does not apply shall file a written certification with the Regional Water Management Division Director, Environmental Protection Agency, in the appropriate regional office. This certification shall include the findings supporting this determination and the results of public comments, and public hearing if held.
NR 252.04(3)(c)
(c) On February 10, 1984, EPA shall acknowledge to the POTW receipt of any certification submitted under
pars. (a) and
(b), and shall indicate to the POTW the adequacy of the submission based upon a review of the factors set forth in
sub. (2).
NR 252.04(3)(d)
(d) Within 30 days of the date of receipt of adequate submissions under
pars. (a) to
(c), EPA shall publish a notice in the federal register identifying those facilities to which the sulfide pretreatment standards of this part do not apply.
NR 252.04(3)(e)
(e) A POTW may certify that the sulfide pretreatment standards of this chapter do not apply to a new source planning to discharge into the POTW. This certification shall be submitted prior to the commencement of discharge, and shall conform at a minimum with criteria in
sub. (2) and the general procedures and intervals of time contained in
pars. (a) to
(d).
NR 252.04(4)
(4) Applicability of sulfide pretreatment standards. NR 252.04(4)(a)(a) If, after EPA and the POTW have determined in accordance with this section that the sulfide pretreatment standards of this chapter are not applicable to specified facilities, a POTW then determines that there have been changed circumstances which justify application of the sulfide pretreatment standards, the POTW shall revoke the certification submitted under
sub. (3). Circumstances include, but not are not limited to, changes in the factors specified in
sub. (2). The POTW and EPA shall then adhere to the general procedures and time intervals contained in
sub. (3) in order to determine whether the sulfide pretreatment standards contained in this chapter are applicable.
NR 252.04(4)(b)
(b) If pursuant to
par. (a) the sulfide pretreatment standards of this chapter are applicable to a specified facility, the indirect discharger shall comply with the sulfide pretreatment standards no later than 18 months from the date of publication of the federal register notice identifying the facility.
NR 252.04(4)(c)
(c) At any time after October 13, 1983, if a POTW determines that there have been changed circumstances which include, but are not limited to, changes in the factors specified in
sub. (2), it may initiate proceedings contained in
sub. (3) to determine that the sulfide pretreatment standards of this section shall not be applicable. The POTW and EPA shall follow the procedures and time intervals contained in
sub. (3) to make this determination. A final determination that the sulfide pretreatment standards are not applicable shall be made prior to the discharge of sulfide not in accordance with the standards set forth in this chapter.
NR 252.04 History
History: Cr.
Register, October, 1986, No. 370, eff. 11-1-86;
cr. (4), Register, May, 2001, No. 545, eff. 6-1-01.
NR 252.05
NR 252.05 Compliance date for pretreatment standards for existing sources (PSES). Existing sources subject to PSES shall comply by November 25, 1985.
NR 252.05 History
History: Cr.
Register, October, 1986, No. 370, eff. 11-1-86.
NR 252.06
NR 252.06 Monitoring requirements. Compliance with monthly average discharge limitations is required regardless of the number of samples analyzed and averaged.
NR 252.06 History
History: Cr.
Register, October, 1986, No. 370, eff. 11-1-86.
NR 252.10
NR 252.10 Applicability; description of the hair pulp, chrome tan, retan-wet finishing subcategory. The provisions of this subcategory are applicable to process wastewater discharges resulting from any tannery which, either exclusively or in addition to other unhairing and tanning operation, processes raw or cured cattle or cattle-like hides into finished leather by chemically dissolving the hide hair, chrome tanning, and retan-wet finishing.
NR 252.10 History
History: Cr.
Register, October, 1986, No. 370, eff. 11-1-86.
NR 252.11
NR 252.11 Effluent limitations representing the degree of effluent reduction attainable by the application of the best practicable control technology currently available (BPT). Except as provided in
40 CFR 125.30-
125.32, any existing point source subject to this subcategory shall achieve the following effluent limitations representing the degree of effluent reduction attainable by the application of the best practicable control technology currently available (BPT):
-
See PDF for table 
NR 252.11 Note
1Within the range 6.0 to 9.0.
NR 252.11 History
History: Cr.
Register, October, 1986, No. 370, eff. 11-1-86;
am. Table, Register, May, 2001, No. 545, eff. 6-1-01.
NR 252.12
NR 252.12 Effluent limitations representing the degree of effluent reduction attainable by the application of the best conventional pollutant control technology (BCT). Except as provided in
40 CFR 125.30-
125.32, any existing point source subject to this subcategory shall achieve the following effluent limitations representing the degree of effluent reduction attainable by the application of the best conventional pollutant control technology (BCT): The effluent limitations are those for BOD
5, TSS, oil and grease, and pH contained in
s. NR 252.11.
