Environmental Health & Safety

Blow Down Management Policy


January 2010

 

Scope:

In accordance with Amherst College Plans, Policies and Standard Operating Guidelines, the Amherst College Environmental Health & Safety Committee and the Environmental Compliance Committee have instituted this Boiler Plant / Cooling Tower Blow Down Management Plan for water discharge into the sanitary sewer system.

Purpose:

The Blow Down Management Plan is a standard operating guideline that was developed by Amherst College in cooperation with the Town of Amherst, Department of Public Works and the Water Treatment Facility. At the recommendation of the town, Amherst College has opted to test waste water at the point of discharge from all cooling towers and the boiler plant. Provided the results of each sample remain below required reporting levels, the Town of Amherst, at the discretion of the water superintendent will furnish the College with a letter that indicates that discharge permits for Amherst College will not be necessary. With the exception of the material that may be discharged into the sanitary sewer from the blow down, Amherst College has and will continue to prohibit the disposal of any hazardous material or waste into either the sanitary sewer or storm water system.
  • See Sink Notice Placard identified in the Environmental section of the Environmental Health & Safety Polices and Procedures table of contents.

Applicability:

The College through an independent, accredited laboratory will perform The Boiler Plant and Cooling Tower Blow Down tests at least twice per year. The samples (tests) will occur at the same time each year or as determined by the water superintendent for the Town. The samples will be taken from the Boiler Plant and Merrill Science Center Cooling Tower every 3 months (January, April, July and October) and from the other seven cooling towers twice annually (January and July). In order to negate the need for a discharge permit, Amherst College will sample the waste water leaving the cooling towers and boiler plant for the following:
  1. Biochemical Oxygen Demand or BOD: < 5mg/Liter
  2. pH: Between 6.8 and 8.5
  3. Settable Solids or SS < 1mg/Liter
  4. Total Suspended Solids or TSS < 3mg/Liter

Boiler Plant Water Testing Procedures

In accordance with the Betz-Dearborn Water Management System, the Amherst College Boiler Plant Supervisor shall personally conduct or verify that periodic tests to control limits for the boiler / condensate are being performed. Boiler Plant personnel shall check water samples for Alkalinity, Conductivity, Hardness, pH, Phosphates and Sulfites in an effort to keep potential problems in check.
  • A copy of the Betz-Dearborn Water Treatment Test Procedure has been incorporated into this policy for future reference.
Test Control Limits System
Alkalinity 400 - 600 ppm Boiler
Conductivity 1500 - 2000 umhos/cm Boiler
Hardness <2 ppm Make-Up Water
pH 8.0 - 8.6 Condensate
Phosphate 30 - 60 ppm Boiler
Sulfite 30 - 60 ppm Boiler

 

A. Boiler Plant Blow Downs

Blow Downs into the sanitary sewer system occur:

  • During each 8 hour shift (3 times per day)
  • Discharge approximately 10 seconds each
In an effort to better understand what we are discharging, and to verify proper concentrations below the regulatory requirements, Amherst College has, in addition to following manufacturer specifications opted to test the water from the Boiler Plant blow down at the point of discharge four times per year, as indicated above. From the Boiler Plant, through an accredited, independent testing laboratory, Amherst College Physical Plant will test the discharged water in January, April, July and October for;
Test Limit
Alkalinity 0
Ammonia 0
Biochemical Oxygen Demand <5 mg/L
Calcium 0
Chloride 250
Conductivity 0
Copper 1.0
Dissolved Solids 0-500
Fecal Coliform 0/100 mL
Hardness 0
Iron 0.3
Magnesium 0
Manganese 0.05
Nitrate 10.0
Nitrite 1.0
pH 6.5-8.5
Potassium 0
Sediment (-) or (+)
Settable Solid < 1 mg/L
Sodium 20.0
Sulfate 250

The above water testing shall be conducted by the accredited, independent laboratory of;

Quabbin Analytical Laboratory

4 Stadler Street
Belchertown, MA 01007
Phone: (413) 323-7134

B. Water Softener Procedures

Water contains impurities that are either dissolved or suspended. “Hard water” holds higher concentrations of calcium and magnesium salts that are dissolved in the water. If used for boiler water, hard water will form scale inside the boiler tubes as the calcium and magnesium salts come out of solution at high temperatures. This causes hard scale to form, which impedes heat transfer from the tube to the water. The tube will overheat and eventually rupture. In an effort to prevent the “hard” water from passing through the boiler tubes, Boiler Plant personnel allow the water to enter a tank of water softener containing sodium zeolite. The Zeolite material exchanges calcium and magnesium ions for sodium ions, which will not damage the boiler or boiler tubes. In order to charge the Zeolite, Boiler Plant staff mix the water with sodium chloride (99.5%). They pump the Sodium Chloride from the brine tank into the top of the tank where it flows down through the bed and charges the material with sodium. When the desired level of sodium brine is placed into the tank, they rinse the Zeolite down to remove any excess sodium. Water is put into the top of the tank, flows through the bed and out into the sewer. The discharged water will be higher in sodium, because the excess was removed from the Zeolite material.

  • The rinse activity takes approximately 2 hours, and the water is tested until it becomes soft and then it is put into service.
  • The above process continues until the Zeolite bed is no longer able replace the calcium and magnesium with sodium. Information provided to Amherst College by the Town of Amherst and the Amherst Environmental Laboratory indicate that the discharge of sodium into the sanitary sewer system is not a monitored or permitted.

Cooling Tower Water Testing Procedures

A. Water Sample Testing

Water samples for Amherst College Cooling Towers are taken three times per week by Mechanical Shop Staff . The tests are performed:

  • Monday
  • Wednesday
  • Friday
  • Corrosive Resistant Apron
  • Corrosive Resistant Gloves
  • Splash Goggles and
  • Face Shield
B. Reasons for Water Testing
  • To determine chemical concentration being added to the water
  • To evaluate the biocides
  • To determine possible discharge into the sanitary sewer as required by the Town of Amherst.
C. GE Betz Water Treatment System

Amherst College Physical Plant currently uses the GE Betz Water Treatment System for our cooling towers. Material Safety Data Sheets for these systems are maintained in close proximity to the individual testing sites and within the Amherst College Physical Plant, Adjacent to the Campus Police Department. They are available for review and copy 24 hours per day.

The company and address for the water treatment system is:

GE Betz Water Management, Inc.

, MA
Telephone: ( )
Fax: ( )

D. Water Treatment Monitoring

The Liquitron DC 1000 monitors the water treatment systems.

  • When the monitor indicates a reading of 800, a blow down occurs.
  • The blow down can take between 1 and 60 minutes to complete.
  • When the monitor level is reduced from 800 to 600, the blow down will stop
E. Water Treatment Additives

The water treatment system is augmented by the following chemicals, which are added on an as needed basis. The Betz-Dearborn water treatment materials that are added include:

  • Air Con CX
  • AL-15
  • Algaecide DM
    Air Con CX is added to the system every day, as needed
  • AL-15 and the Algaecide DM are alternated weekly.
The water treatment chemicals referenced above are stand alone containers that automatically inject the proper amount of chemicals to control algae and other water borne hazards such as Legionella.
  • Air Con CX 15 gallons
  • AL-15 5 gallons
  • Algaecide DM 5 gallons
    The water treatment chemicals are in see-through containers that are inspected daily to verify that the proper amounts are being added.
  • If to much is being added, Physical Plant staff cut it back
  • If insufficient, Physical Plant staff add more
Water analysis is performed 3 days a week.
  • Monday, Wednesday and Friday
Biocides are checked using Betz-Dearborn Water Testing Equipment
  • Algae growth is monitored
  • The sample must be checked within 48 hours or the test is void
  • If the growth of algae is limited, the test passes
  • Take a pre-specified amount of water into a test tube that is provided at the Betz-Dearborn station.
  • Add (1) level scoop of molybdate reagent
  • Add (5-7) drops of hydrochloric acid (HCl)


In an effort to better understand what we are discharging, and to verify proper concentrations below the regulatory requirements, Amherst College will test cooling tower blow downs at the point of discharge from Merrill Science Center / Life Sciences four times per year and all other cooling towers, twice annually. The tests will be performed by an accredited, independent testing laboratory, referenced below. Amherst College Physical Plant will test the discharged water from Merrill Science in March, July and October for:

Test Limit
Alkalinity 0
Ammonia 0
Biochemical Oxygen Demand < 5mg/L
Calcium 0
Chloride 250
Conductivity 0
Copper 1.0
Dissolved Solids 0 - 500
Fecal Coliforms 0/100 mL
Hardness 0
Iron 0.3
Magnesium 00
Manganese 0.05
Nitrate 10.0
Nitrite 1.0
pH 6.5 - 8.5
Potassium 0
Settlement (-) or (+)
Settable Solids < 1 mg/L
Sodium 20.0
Sulfate 250

The water samples taken from the other cooling towers in January and July will be tested for:

  1. Biochemical Oxygen Demand or BOD: < 5mg/Liter
  2. pH: Between 6.8 and 8.5
  3. Settable Solids or SS < 1mg/Liter
  4. Total Suspended Solids or TSS < 3mg/Liter
Quabbin Analytical Laboratory

4 Stadler Street
Belchertown, MA 01007
Phone: (413) 323-7134