Attachment 12 2025 NPDES ANNUAL BIOSOLIDS REPORT

INTERNATIONAL BOUNDARY AND WATER COMMISSION

UNITED STATES AND MEXICO

UNITED STATES SECTION

SOUTH BAY INTERNATIONAL

WASTEWATER TREATMENT

PLANT

Prepared By:

2025 ANNUAL BIOSOLIDS REPORT

February 10, 2026

Ms. Emily Allen
International Boundary and Water Commission
2995 Clearwater Way,
San Diego, CA 92154
Subject: 2025 IBWC SBIWTP Biosolids Report
Dear Ms. Allen:
I am pleased to provide the attached 2025 IBWC SBIWTP Biosolids Report for your review. I believe this report to be complete and accurate in all details. Should you require additional information or further copies of the report, please do not hesitate to ask.
Regards,

Jacob Schmidt
Jacob Schmidt
Plant Superintendent

January 2025

Stabilized Biosolids

Dried Sludge

USST Raw Sludge

Analyte

pH

%Total Solids

%Total Solids

%Total Solids

Method

EPA 9045

EPA 2540 G

EPA 2540 G

EPA 2540 G

MDL

0.1

0.01

0.01

0.01

Date and Time Sampled

Truck#

Test#

01/01/2025 0:00:00

4697

01-01

6.78

21.1

01/02/2025 0:00:00

01-02

6.83

19.1

19.5

01/03/2025 0:00:00

01-03

6.84

18.2

18.2

01/04/2025 0:00:00

01-04

6.79

19.5

01/05/2025 0:00:00

01-05

6.73

18.5

17.6

01/06/2025 0:00:00

01-06

6.83

19.4

19.5

01/07/2025 0:00:00

01-07

6.94

19.1

18.9

01/08/2025 0:00:00

01-08

6.87

20.2

20.3

01/09/2025 0:00:00

01-09

6.83

18.5

18.2

01/10/2025 0:00:00

01-10

6.71

18.7

01/11/2025 0:00:00

01-11

6.78

18.2

19.4

01/12/2025 0:00:00

01-12

6.7

18.4

19.6

01/13/2025 0:00:00

01-13

6.73

21.9

21.7

01/14/2025 0:00:00

01-14

6.77

21.5

21.8

01/15/2025 0:00:00

01-15

6.75

20.6

20.8

01/16/2025 0:00:00

01-16

6.75

21.3

21.6

01/17/2025 0:00:00

01-17

6.79

24.4

23.1

01/18/2025 0:00:00

01-18

6.82

19.6

19.9

01/19/2025 0:00:00

01-19

6.87

18.1

01/20/2025 0:00:00

01-20

6.87

20.3

01/21/2025 0:00:00

01-21

6.79

19.4

01/22/2025 0:00:00

01-22

6.83

23.5

22.8

01/23/2025 0:00:00

01-23

6.76

22.5

22.1

01/24/2025 0:00:00

01-24

6.74

19.9

19.4

01/25/2025 0:00:00

01-25

6.81

18.7

01/26/2025 0:00:00

01-26

6.74

18.5

18.7

01/27/2025 0:00:00

01-27

6.78

23.8

23.2

01/28/2025 0:00:00

01-28

6.89

26.8

26.2

01/29/2025 0:00:00

01-29

6.94

26.8

01/30/2025 0:00:00

01-30

6.9

25.1

26.7

01/31/2025 0:00:00

01-31

6.84

19.8

22.7

4.10

3.86

4.92

5.38

January 2025

Date Sampled:

01/06/2025

01/06/25
Dried Solids

Constituent

Test method

RL

Units

Stabilized Solids

pH

EPA 9045

0.10

pH

6.83

6.8

Percent Total Solids

EPA 2540G

0.01

%

19.4

19.5

Percent Total Volatile Solids

EPA 2540G

0.01

%

14.60%

14.7

Coliform-Fecal

SM 9221

1000

MPN/g

1600000

-

"Dry Weight"

Coliform-Total
Antimony
Antimony STLC
Arsenic
Arsenic STLC
Barium
Barium STLC
Beryllium
Beryllium STLC
Cadmium
Cadmium STLC

SM9221

1000

MPN/g

>1600000

-

EPA 3050/6010D

mg/kg

ND

ND

EPA 6010D

-

mg/L

-

-

EPA 3050/6010D

mg/kg

ND

ND

EPA 6010D