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A septic tank and drainfield combination is a fairly common type of on-site sewage facility in the Western world. OSSFs account for approximately 25% of all domestic wastewater treatment in the US. Onsite sewage facilities may also be based on small-scale aerobic and biofilter units, membrane bioreactors or sequencing batch reactors.
The decision to build a combined sewer system or two separate systems is mainly based on the need for sewage treatment and the cost of providing treatment during heavy rain events. Many cities with combined sewer systems built their systems prior to installing sewage treatment plants, and have not subsequently replaced those sewer systems. [2]
These stages increase the initial cost of the aerobic system, and also the maintenance requirements over the passive septic system. Unlike many other biofilters, aerobic treatment systems require a constant supply of electricity to drive the air pump increasing overall system costs. The disinfectant tablets must be periodically replaced, as ...
A cost estimator will typically use estimating software to estimate their bid price for a project, which will ultimately become part of a resulting construction contract. Some architects, engineers, construction managers, and others may also use cost estimating software to prepare cost estimates for purposes other than bidding such as budgeting ...
A pivot table in BOEMax, a Basis of Estimate software package. To create a BOE companies, throughout the past few decades, have used spreadsheet programs and skilled cost analysts to enter thousands of lines of data and create complex algorithms to calculate the costs. These positions require a high level of skill to ensure accuracy and ...
A cost estimate is the approximation of the cost of a program, project, or operation. The cost estimate is the product of the cost estimating process. The cost estimate has a single total value and may have identifiable component values. A problem with a cost overrun can be avoided with a credible, reliable, and accurate cost estimate. A cost ...
For example, it is estimated that 500 million m 3 of contaminated water per year can leak into soil and ground-water in Germany. [4] The rehabilitation and replacement of damaged sewers is very costly. Annual rehabilitation costs for Los Angeles County are about €400 million, [5] and in Germany, these costs are estimated to be €100 million. [6]
The most basic element of a cost estimate and therefore the cost database is the estimate line item or work item. [3] An example is "Concrete, 4000 psi (30 MPa)," which is the description of the item. In the cost database, an item is a row or record in a table (of items) and the description is a column or field for that record.