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APPROVE PILOT STUDY OF CALCIUM NITRATE (BIOXIDE) TO CONTROL ODOR AND CORROSION FOR CITY SEWER INFRASTRUCTURE, APPROVE FINDINGS AND APPROVE AGREEMENT WITH EVOQUA WATER TECHNOLOGIES LLC
recommended action
RECOMMENDATION
It is recommended that the City Council approve a motion to:
1. Approve pilot study of calcium nitrate (Bioxide) to control odor and corrosion for city sewer infrastructure.
2. Approve findings to support and justify an exception to the competitive bidding process.
3. Authorize the City Manager to execute an agreement with Evoqua Water Technologies LLC, of Sarasota, Florida, for the purchase of equipment and calcium nitrate (Bioxide®) in an amount not to exceed $125,000 through a cooperative purchase agreement with Dublin San Ramon Services District.
It is further recommended that the City Manager be authorized to take appropriate and necessary actions to carry out the purpose and intent of this motion.
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Summary
The Municipal Utilities Department (MUD), Collections Division monitors hydrogen sulfide gas (H2S) levels in the City’s gravity sewer collection system. H2S is a byproduct of sewage that, in addition to creating unpleasant odors, is hazardous to the collection systems infrastructure and the environment. Sanitary Sewer Collection System 3 is experiencing high levels of H2S, requiring treatment to mitigate the harmful effects. Evoqua Water Technologies LLC (Evoqua) proposed recommendations for the supply of product, equipment, and services to disperse calcium nitrate (Bioxide®) from the Sanguinetti Sanitary Pump Station to control hydrogen sulfide in Sanitary Sewer Collection System 3 (Attachment A). It is anticipated that the pilot study to disperse the Bioxide® to control hydrogen sulfide gas in Sanitary Sewer Collection System 3 will continue for a period of 9 to 12 months to determine the optimum dosage and effectiveness of this chemical treatment. Thereafter, MUD will return to the City Council with a progress report and recommendations, which could include the purchase of Bioxide® from the BACC in fiscal year 2017-2018.
The selection of Evoqua to conduct a pilot study for odor control and to prevent corrosion of infrastructure is based on their expertise with the use of Bioxide® and availability of a cooperative purchasing agreement through the Bay Area Chemical Consortium (BACC), of which MUD is a participating member (Attachment B). Because this is a pilot program, the exact cost of services by Evoqua is not known, and the agreement is written not to exceed $125,000 as a result.
DISCUSSION
Background
Per Occupational Safety and Health Administration (OSHA) Factsheet, “hydrogen sulfide is a colorless, flammable, extremely hazardous gas with a ‘rotten egg’ smell. In a sewage conveyance system, hydrogen sulfide is produced by bacterial breakdown of organic materials and human and animal waste”. Hydrogen sulfide (H2S) has a permissible exposure limit of 10 parts per million (ppm) with a ceiling of 50 ppm. H2S level at or above 100 ppm is considered an immediate danger to health and safety. H2S also converts to sulfuric acid, which is extremely corrosive to sanitary sewer pipes and manholes.
Routine H2S monitoring indicates average H2S levels in System 3 are 200 to 300 parts per million (ppm) with the peak measurements exceeding 1,000 ppm. Thus, Sanitary Sewer Collection chemical treatment in this sewer collection system is proposed to mitigate the harmful and damaging effects. Previously, MUD piloted an H2S study in Sewer Collection System 7 & 8 utilizing a different product, sodium hydroxide. The pilot was effective in the gravity System 7 & 8; however, the characteristics of the product are not compatible with the mechanical/pressurized nature of System 3. Due to the different system characteristics between System 7 & 8 and System 3, Calcium nitrate (Bioxide®) is the preferred treatment method based on its ability to limit H2S in the gravity sewer collection system and is non-hazardous.
In an effort to reduce the cost of chemicals for water and wastewater treatment, the City joined the BACC in 2013. The BACC is a group of 49 public agencies located throughout the Central Valley and Bay Area that coordinate their chemical bids to obtain the best possible bulk bid prices. DSRSD, the coordinating Agency for BACC, coordinated all bid specification preparations and advertisements in 2016. The MUD participated in the preparation of the bid specifications and was able to select specific chemicals required at the Regional Wastewater Control Facility (RWCF), the Delta Water Treatment Plant (DWTP), and the sanitary sewer collection system. All agencies participating in the BACC reserve the right to purchase any volume of the chemical listed, at the contract price, regardless of the stated estimates of quantities.
Present Situation
The MUD will use two existing chemical tanks that are compatible for storing calcium nitrate at the Sanguinetti Sanitary Pump Station site. Evoqua will supply an Underwriter Laboratory (UL) approved dosing chemical control feed system at a cost of $25,150. The dosing chemical control system was designed by Evoqua with propriety and patented technology otherwise not commercially available. This equipment will be a capital purchase and will be the property of the City of Stockton upon installation. The cost for a one-year pilot study is estimated at approximately $125,000 (approximately $100,000 for Bioxide® at 130 gallons per day, $2.10 per gallon; and $25,150 for the dosing chemical control system).
Evoqua has over 2,000 installations across the United States of nitrate salts for use in odor control applications for municipal wastewater. MUD recommends the use of nitrate salt to control H2S downstream of the Sanguinetti Pump Station. Bioxide® is the product brand recommended as it prevents the production of H2S, thus reducing both odor and corrosion, which protects the pipe and manholes downstream of the system. Evoqua shall provide a supply of Bioxide solution in minimum 2,000 gallon loads (See Attachment B).
Findings
Stockton Municipal Code Section 3.68.070 provides for an exception to the competitive bidding requirements in cases where the City Council has approved findings that support and justify the purchase through a cooperative purchasing agreement (see Attachment C).
Proposed findings to support this purchase are as follows:
1. High levels of hydrogen sulfide gas can pose a health and safety risk, and lead to premature infrastructure failure.
2. This pilot study is an urgent matter due to high hydrogen sulfide readings with peaks (over 1,000 ppm) and averages (200-300 ppm) in this sewer system.
3. The DSRSD formally conducted a competitive bid process for the supply and delivery of calcium nitrate to its Bay Area Chemical Consortium (BACC) member agencies.
4. The bid specifications used by the DSRSD have been assessed as compatible with the City of Stockton standards and requirements.
5. The DSRSD determined the calcium nitrate bid submitted by Evoqua was found to be compliant with the bid specifications and Evoqua was eligible for award of contracts to BACC member agencies for the supply and delivery of calcium nitrate.
6. Evoqua agreed to supply the product, equipment, and services for the chemical application of Bioxide® for odor control downstream of the Sanguinetti Sanitary Pump Station to the City of Stockton Municipal Utilities Department through an Agreement for the Purchase of Goods and Services and utilizing the BACC cooperative purchase agreement for calcium nitrate under the same terms and conditions provided to the DSRSD.
7. Contracting for odor control treatment services and equipment purchases through a cooperative purchase agreement best serves the City and is in the public interest by saving the time, expense on larger scale chemical purchases, and City resources of duplicating a competitive bid process.
Therefore, staff recommends the City Council approve these findings as an exception to the competitive bid process and authorize purchase of calcium nitrate (Bioxide) for injection at the Sanguinetti Sanitary Pump Station to control odor and corrosion in Sanitary Sewer Collection System 3 in an amount not to exceed $125,000.
FINANCIAL SUMMARY
There are sufficient funds for FY 2016-17 in the Wastewater Operating Expense Account 431-4332-571 to enter into this purchase agreement with Evoqua Water Technologies LLC, of Sarasota, Florida in the amount not to exceed $125,000.
There is no impact to the City’s General Fund or to any other unrestricted fund as a result of taking the recommended actions.
Attachment A - Evoqua Proposal
Attachment B - Cooperative Service Contract
Attachment C - Agreement - Evoqua Water Technologies
Attachment D - Notice of Intent