BID 2022-106 - Clarifying Questions 1.pdf

INVITATION TO BID #2022-106

FISCHER’S FOREST PARK:

LARGE ONSITE SEWAGE SYSTEM TREATMENT PROCESS UPGRADE

RESPONSE TO CLARIFYING QUESTIONS #1

January 26, 2023

Note that these are questions submitted by interested firms to the above referenced solicitation.

The below answers are for clarification purposes only and in no way alter or amend the BID as published.

1. How is the contractor intended to cover the drip tuning? Are they expected to import dirt or sand?

Answer: Drip tubing is to be installed into the native soil using a drip tube laying machine that is compatible with the tubing specified in the bid package documents. No importation of cover material is anticipated. Protecting and maintaining the integrity of the native soil is critical to the proposed treatment design and no substitutions or deviations will be allowed, including surface scarification or tilling as that will compromise the soil structure intended to receive treated effluent. If installation is delayed until drier summer months, hardened soils may make installation in one pass difficult due to tube laying shank refusal/increased resistance. For this scenario, previous installation in substantially similar soils have successfully installed drip tubing by making a first pass of a tractor mounted tube laying machine without tubing and shanks set to 75% of target burial depth. A second pass with tubing is then made and the resistance is adequately reduced from the first pass.

2. Does the manhole need to be field fit?

Answer: Field fitting is intended to pertain to the pipe connections from existing infrastructure to new infrastructure at indicated tie-in points using means to provide a water-tight connection with appropriate material as specified in the bid documents or Onsite Wastewater Treatment System Rules and Construction Standards (Oregon Administrative Rules [OAR], Chapter 340, Divisions 71 and 73), as approved by the designer/owner. Close attention to grades and relative elevations is critical to make sure there is adequate fall where gravity flow is required. The final location of some items is not critical. Certain items, such as the east septic tank and corresponding new manhole, will need to be installed at elevations and locations suitable to tie into existing pipe systems and not compromise the existing system’s functionality. Although elevations for the east septic tanks are given in the bid documents, the final elevation may need to be adjusted based on the actual depth of the existing 4” gravity effluent sewer line. Similarly, the final elevation of other structures, such as the recirculation tanks, may not need to meet the design elevations exactly so long as the relative elevation changes between the tanks, advanced treatment units, flow splitter basin, and dosing tank conversion remains the same as shown in the bid documents. For proposed substantial deviations from the provided bid documents, the designer is to be notified prior to construction.

3. Is the contractor responsible for designing bypass pumping?

Answer: The Contractor must install the new system components in a manner to maintain functional operation of the existing system during construction. Bypass pumping may be needed if the Contractor is unable to maintain normal system operations, existing components are damaged, and/or to facilitate parts of construction. The method and extent of bypass pumping is considered means & methods and, pending approval from the designer/owner, up to the Contractor.

The Contractor will need to pump and manage the level of the dosing tank or other septic tanks as needed to serve as storage while making connections or fixing broken pipes. Upon commissioning of the system, a final tie-into plumbing connection of the converted dosing tank into the new treatment system and dripfield will occur, followed by decommissioning of existing components as described in the plans. The Contractor shall make arrangements to pump and haul sewage or effluent to a local Publicly Owned Treatment Works or Wastewater Treatment Facility licensed to receive the material.