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HomeMy WebLinkAbout11284RESOLUTION NO. 11284 A RESOLUTION APPROVING REVISIONS TO THE SANITARY SEWER DESIGN CRITERIA AND POLICIES MANUAL FOR THE CITY OF PUEBLO BE IT RESOLVED BY THE CITY COUNCIL OF PUEBLO, COLORADO, that: SECTION 1 Upon commendation by the City Engineer, the Council does hereby approve the revisions to sections 4.14 and 4.17 of the Sanitary Sewer Design Criteria and Policies Manual for the City of Pueblo, Colorado as shown on the documents attached hereto. SECTION 2_ After adoption of this Resolution, a true copy of the Sanitary Sewer Design Criteria and Policies Manual for the City of Pueblo, as revised, shall be maintained on file in the office of the City Clerk for public inspection. Copies shall be made available through the City's Department of Public Works for purchase by the public at a moderate price. SECTION 3_ This Resolution shall become effective upon final passage and approval; however, the revision to the Sanitary Sewer Design Criteria and Policies Manual for the City of Pueblo adopted hereby shall become effective thirty days after passage of this Resolution. INTRODUCED April 28, 2008 BY Judy Weaver Councilperson AP PROVE LA HL- ATTEST ED BY: Cff. � y PPI`81f I T' i I AGENDA ITEM # I- DATE: APRIL 28, 2008 DEPARTMENT: WASTEWATER DIRECTOR — GENE MICHAEL TITLE A RESOLUTION APPROVING REVISIONS TO THE SANITARY SEWER DESIGN CRITERIA AND POLICIES MANUAL FOR THE CITY OF PUEBLO ISSUE Should the City Council approve various revisions to the Sanitary Sewer Design Criteria and Policies Manual for the City of Pueblo RECOMMENDATION Approval of this Resolution BACKGROUND The City's Sanitary Sewer Design Criteria and Policies Manual, which was adopted by City Council in May of 1999 and revised in December 2003, May 2006, and June 2007, governs the design of sanitary sewers, master planning for development, and operation and maintenance of sanitary sewers. Certain modifications are necessary to protect the City of Pueblo's sanitary sewer system from hydrogen sulfide production. A summary of the key elements of this revision follows: 1. Chapter 4, Section 4.14 — Hydrogen Sulfide Production The modification of this section will require an epoxy lining for manholes or other structures designated by the Wastewater Department to protect against corrosion. 2. Chapter 4, Section 4.17 — Epoxy Coating The addition of this section will give basic specifications for the epoxy coating that is required to be put on the interior surface of structures designated by the Wastewater Department. FINANCIAL IMPACT The proposed revisions will have no impact on City costs. However, construction costs for private developers will increase in some cases. unless deemed unnecessary by the City as determined on a case by -case basis. In the absence of impervious soils, caissons shall extend twenty feet below the invert of the sewer main. 4.13 RAILWAY AND HIGHWAY CROSSINGS Design of crossings shall conform to the requirements of the Railroad Company or the Colorado Department of Transportation. 4.14 HYDROGEN SULFIDE PRODUCTION [(FORCE MAINS AND INVERTED SIPHONS)] Short and long term hydrogen sulfide production effects within any Sanitary Sewer System should be addressed by the designer particularly with respect to identifying and pinpointing those locations where high generation potential is likely. The effect of deterioration caused by hydrogen sulfide must be assessed in designing pipelines to ensure that a fifty (50) year operational life is provided by the design. The following settings have the potential to generate high levels of hydrogen sulfide: Areas of high - turbulence in the stream -flow which generate disagreeable and unacceptable levels of hydrogen sulfide gas. 2. Areas where sulfide levels equal or exceed 1 mg/liter and rates of flow are low without benefit of daily cleansing/oxidation velocities, or where detention creates a loss of free oxygen levels below 50% of normal. 3. In areas where stream temperatures rise above the normal within the sewer line environment due to highly thermal discharge points or sources. Design approaches which [should be considered] will be required in avoiding or reduction of corrosive or malodorous gas and in providing for greater pipeline and manhole design life are: Use of pipe material which does not react to acid attack (e.g. PVC). 2. For pipe sizes greater than 27 ", use a pipe material only as approved by Director of Public Works. 3. Treatment of flows with chlorine, lime, iron or zinc salts, hydrogen peroxide or nitrate chemical compounds in sufficient quantities to eliminate dissolved sulfide based upon a periodic maintenance schedule for the length of pipeline affected. Providing a coating or sleeve inside the pipeline with a material which is non - reactive to hydrogen sulfide (beware of fabrication faults however, which may accentuate sulfide concentrative deterioration). 5. Epoxy lining of manholes or other structures constructed on backbone systems. 32 6. Increasing the size of pipe above the "otherwise appropriate design', even though the larger pipe is seemingly oversized for the design flow. This design measure is intended to increase the wastewater surface area leading to greater reservation and less sulfide generation. Also, the perimeter of the sewer (and thus "dry" surface area) increases with increasing pipe size leading to less wall penetration from a given amount of acid. 4.15 CONCRETE PROTECTION IN HIGH- SULFATE SOILS High- sulfate soils are common throughout Pueblo. To protect concrete installations from corrosion in high- sulfate soils, all concrete mixes must comply with the specifications presented in Article 4 of the Standard Construction Specifications and Standard Details for the City of Pueblo, Colorado, February 26, 2001, and as same may be amended. 4.16 PROTECTING EXISTING SEWER SYSTEM DURING CONSTRUCTION New sewer mains shall remain functionally disconnected from the existing sanitary sewer system during construction to prevent dirt and debris from entering the existing sewer system. Connection of new sanitary sewer mains to the existing sewer system shall be made at an existing manhole where feasible. Where a sanitary sewer main is connected to the existing system between existing manholes, a new manhole shall be constructed at the point of connection. The connection of all new sanitary sewer mains to the existing sanitary sewer system shall be accomplished in such a manner that all existing services are maintained, and that no refuse, concrete, asphalt or other extraneous matter enter the existing sewer. The Wastewater Department shall install a debris trap in the sanitary sewer system at the connection manhole or at another appropriate location to prevent the introduction of construction debris, refuse, concrete, asphalt, or other extraneous matter into the sanitary sewer collection system. The debris trap shall be inserted prior to commencement of new sanitary sewer construction, or as soon thereafter as feasible. All inspections required for acceptance of a new sewer in Article 12 of the most recent version of the Standard Construction Specifications and Standard Details for the City of Pueblo, Colorado shall be completed, and the street overlying the new sanitary sewer shall be paved, prior to the new sanitary sewer being accepted by the City and placed in operation. Following completion of paving, the new sanitary sewer shall be flushed and inspected again to ensure that is free from construction- related debris. The developer or contractor shall be required to clean the new sewer as needed to ensure that all construction- related debris is removed prior to removing the debris trap and allowing the new sanitary sewer to be placed in operation. During construction it shall be the sole responsibility of the developer or contractor to ensure that any liquid and debris from the new sewer system is removed from any accumulation point or from the ground, and disposed of in a manner that complies with all federal, state and local environmental and community health regulations. The developer or contractor shall ensure that water debris from the new sanitary sewer construction do not cause or contribute to a nuisance condition. 33 4.17 EPDXY COATING The interior surface of the manholes on backbone systems will be lined with a 100% solid self - priming, ultra -high build epoxy applied to a minimum thickness of 100 mils with an airless spray gun applicator. Protective lining shall completely cover all manhole bases including inverts Epoxy coating shall conform to the following performance testing DESCRIPTION METHOD RESULTS Flexural Strength ASTM D790 13 000 psi Compressive Strength ASTM D695 18,000 psi Tensile Strength ASTM D638 7,600 psi Tensile Ultimate Elongation ASTM D638 1.5% Hardness, Shore D ASTM D2240 88 Water Vapor Transmission ASTM D 1653 Method B 3 8 ig ns /sp m per 24hrs Taber Abrasion, CS 17 Wheel ASTM D4060. 1000g load/1000 cycles <112mg loss Temperature Resistance ASTM D4541, Concrete 200 deg F 34