HomeMy WebLinkAboutW-2024-0935_OSHKOSH_ATF Sodium hydroxide chemical feed pump_REVIEW
October 31, 2024
DIANE BARTLETT CLERK
CITY OF OSHKOSH
215 CHURCH AVE
PO BOX 1130
OSHKOSH WI 54903-1130
Project Number:
PWSID#:
DNR Region:
County:
W-2024-0935
47104574
NER
Winnebago
SUBJECT: AFTER-THE-FACT WATER SYSTEM FACILITIES PLAN AND SPECIFICATION REVIEW
Dear Ms. Bartlett:
The Wisconsin Department of Natural Resources (department), Division of Environmental Management, Bureau
of Drinking Water and Groundwater has reviewed the after-the-fact submittal for sodium hydroxide chemical feed
pumps installed without prior department review and approval. The plans and specifications are being placed on
file without approval.
Water system name: Oshkosh Waterworks
Date received: 10/28/2024
Engineering firm: Donohue & Associates, Inc.
Professional Engineer: Susan Wojtkiewicz, P.E.
Regional DNR Contact: Jamie Douglas, 3369 West Brewster Street, Appleton WI 54914-1602, (920) 362-6629,
jamie.douglas@wisconsin.gov
DNR Plan Reviewer: Ken Scherer, 101 South Webster Street, Madison, WI 53703, (715) 520-3981,
kenneth.scherer@wisconsin.gov
Project description: On behalf of the City of Oshkosh (City), Donahue & Associates, Inc. has submitted plans
and specifications for after-the-fact review for the installation of sodium hydroxide chemical feed pumps at the
water treatment plant (WTP) without prior department review and approval.
Background: The original plans and specifications for modification of the corrosion control treatment (CCT)
chemical feed systems at the WTP were reviewed and approved under department project number W-2023-0590
and approval letter dated August 11, 2023. The originally proposed chemical feed pumps were replaced with
pumps of a different capacity without prior department review and approval.
Sodium hydroxide chemical feed system modifications: The two existing sodium hydroxide chemical feed pumps
located within the chemical feed building were replaced with two sets of new chemical feed pumps. Two new
Milton Roy Model No. MRB - GLOBAL MROY A, maximum 148.8 gallons per day, electronic positive
displacement chemical feed pumps and two new Milton Roy Model No. MRB - GLOBAL MROY B, maximum
2,040 gallons per day, electronic positive displacement chemical feed pumps are used to feed a solution of
ANSI/NSF 60 certified 30% active liquid sodium hydroxide (caustic soda) into the existing meter vault located
between the CT/backwash supply tank and the clearwells for pH adjustment and distribution system corrosion
State of Wisconsin
DEPARTMENT OF NATURAL RESOURCES
101 S. Webster Street
Box 7921
Madison WI 53707-7921
Project Number: W-2024-0935 Page 2 of 3
control purposes. The existing chemical injection locations in the meter vault are not always under positive
pressure and are not located in the bottom half of the piping. These issues have been identified in the past and the
department understands that it will be addressed and corrected in a future WTP renovation project. Two sets of
pumps are proposed because of the large WTP flow and finished water pH fluctuations requiring the operators to
monitor pH continuously and manually adjust feed rates as needed. At the minimum 6.5 million gallons per day
(MGD) WTP flow rate and the minimum 1.8 mg/L dose rate, the anticipated chemical feed pump settings will be
20% of the overall capacity of the pump. The minimum anticipated sodium hydroxide chemical feed rate will be
1.2 gallons per hour and the estimated daily use will be 29 gallons per day based on 24 hours of operation. At the
maximum 13.7 MGD WTP flow rate and the 32.2 mg/L maximum dose rate, the anticipated chemical feed pump
setting will be 53% of the overall capacity of the pump. The maximum anticipated sodium hydroxide chemical
feed rate will be 45 gallons per hour and the estimated daily use will be 1,085 gallons per day based on 24 hours
of operation. See Condition No. 1.
The chemical feed pumps will be flow paced by a control loop using 4 to 20 mA signals from multiple flow
meters, including four flow meters on the GAC contactor effluents. Back-pressure valves, pressure gauges, and
pressure relief valves will be installed in the chemical feed pumps discharge piping. The chemical feed pumps
will take suction from the existing 245-gallon polyethylene chemical solution day tank. The bulk tank will be
provided with new 3-inch diameter CPVC fill lines extending from the existing fill location to the tank.
The chemical feed pumps will connect to new sodium hydroxide feed pump discharge lines within the WTP
building and the existing chemical injectors within the existing meter vault. Reportedly, the WTP discharge
piping includes an existing entry point sample faucet.
After-the-fact review: The department will allow the replacement chemical feed pumps to remain in service
subject to the conditions of department project number W-2023-0590 and approval letter dated August 11, 2023
and the following conditions related to Chapters NR 810 & 811, Wis. Adm. Code:
1. Feeders shall be able to supply, at all times, the necessary amounts of chemical at an accurate rate,
throughout the range of feed. All positive displacement diaphragm metering pumps shall be operated at a
minimum speed setting of 12 strokes per minute. For positive displacement diaphragm metering pumps
with an adjustable stroke length the pumps shall be operated at a minimum of 20 percent of the maximum
stroke length. (s. NR 811.39(2)(c), Wis. Adm. Code)
2. The electrical outlet for any chemical feed pump shall be clearly marked. (s. NR 811.39 (4)(b)). The
outlet shall be located to allow the chemical pump feed line to be as short as possible in length of run. (s.
NR 811.39(7)(a), Wis. Adm. Code)
3. A permanent sign identifying the chemical tank contents shall be posted adjacent to or on chemical
storage tanks. (s. NR 811.40(1)(0), Wis. Adm. Code)
4. Compliance with local, state, and federal safety codes, including department of safety and professional
services and OSHA codes, for other applicable chemical safety and handling requirements is required. (s.
NR 811.40(1)(p), Wis. Adm. Code)
5. Where the eyes or body of any person may be exposed to injurious corrosive materials, suitable facilities
for quick drenching or flushing of the eyes and body shall be provided as required in s. SPS 332.15. (s.
NR 811.40(2)(e)1., Wis. Adm. Code)
6. Rubber gloves, protective clothing, and safety goggles that form a tight seal with the face shall be
provided for each operator who prepares chemical solutions. (s. NR 811.40(2)(e)2., Wis. Adm. Code)
Please note, in accordance with s. NR 811.08, Wis. Adm. Code, written department approval shall be obtained
prior to starting construction for all reviewable projects as defined by s. NR 108.03 (1), Wis. Adm. Code.
Project Number: W-2024-0935 Page 3 of 3
This is to notify you that future construction or modification of water system improvements or components
without first obtaining the required written approval of the department may result in enforcement action being
taken by the department.
Review constraints: The project was reviewed in accordance with ss. 281.34 and 281.41, Wis. Stats. for
compliance with Chapters NR 108, NR 810, NR 811 and NR 820, Wis. Adm. Code. This review is based upon
the representation that the information submitted to the department is complete and accurately represents the
project being reviewed.
STATE OF WISCONSIN
DEPARTMENT OF NATURAL RESOURCES
Sincerely,
Ken W. Scherer, P.E.
Public Water Engineering Section
Bureau of Drinking Water and Groundwater
cc: Brad Rokus – City of Oshkosh
Susan Wojtkiewicz, P.E. – Donohue & Associates, Inc.
Jamie Douglas – DNR, Green Bay
JaNelle Merry – DNR, Green Bay
Ann Hirekatur – DNR, Madison DG/5
Sam Munk – DNR, Madison DG/5
PSC – Madison