Copper Analysis (With Clean Data)

ATTACHMENT D(1)

Copper Pooled Data Analysis

1. Basis statistics of pooled data.

The following is a basic statistics of all available copper data (time period varies between 1998-2002) from 10 POTWs with activated sludge system, which are Burlingame, CCCSD, Millbrae, North San Mateo, Rodeo, S.F. Airport, City of San Mateo, SBSA, South SF, and SVCSD. Data from SBSA and SVCSD are monthly averages if more than 1 sample is available in a month.

Descriptive Statistics: Copper (ug/L)

Variable N Mean Median TrMean StDev SE Mean

Copper 394 8.972 8.000 8.389 5.306 0.267

Variable Minimum Maximum Q1 Q3

Copper 1.200 47.000 6.000 10.500

Descriptive Statistics: Copper (ug/L) by Discharger

Variable Discharger N Mean Median TrMean StDev

Copper Burlingame 55 9.205 8.000 8.476 5.684

CCCSD 37 5.457 5.500 5.476 1.290

Millbrae 43 11.73 10.00 10.65 7.90

N. SanMateo 16 10.150 10.000 10.100 2.062

Rodeo 25 4.988 5.000 4.987 1.735

S.F. Air 40 8.890 7.750 8.386 5.311

SanMateo 39 7.392 6.300 7.117 3.208

SBSA 44 10.793 10.650 10.899 2.644

So. SF 53 10.90 9.70 9.83 7.32

Sonoma 42 8.069 7.600 7.919 2.455

Variable Discharger SE Mean Minimum Maximum Q1 Q3

Copper Burlingame 0.766 3.000 45.000 6.800 10.000

CCCSD 0.212 2.000 8.000 4.650 6.400

Millbrae 1.20 3.00 42.00 7.10 13.00

N. SanMateo 0.516 5.000 16.000 10.000 10.300

Rodeo 0.347 2.000 8.000 3.300 6.500

S.F. Air 0.840 1.200 32.000 5.750 11.075

SanMateo 0.514 2.900 19.000 5.200 9.000

SBSA 0.399 4.000 15.020 9.521 12.750

So. SF 1.00 1.60 47.00 7.35 12.00

Sonoma 0.379 3.360 18.950 6.570 9.496

2. Box plot of the copper effluent concentration by discharger.

3. Probability distribution analysis using Mini Tab.

99.87th percentile = 33.8 ug/L

4. Summary:

The performance based effluent limit derived from 10 POTWs with activated sludge treatment system is 34 ug/L, and is used as the monthly average interim limit.

Napa SD Permit Amendment, Tentative Order 1 8/27/2002