ERC calculator petroleum and gas - Module 12 transcript

Watch the video Petroleum and gas ERC calculator training – Module 12 – Water storage to learn about entering data into the Water Storage and Water Storage User Build sheets and work through examples.

Welcome back to the training for the 2022 edition of the estimated rehabilitation cost calculator for petroleum and gas. This is Module 12. This module will work through entering data into the Water Storage and Water Storage User Build input sheets.

The Water Storage input sheet uses the same by area rates as the Main sheet. The default view of this sheet shows the range of options across the drop-down menus in columns E through H. For example the first twelve rows show the 0 to 50 megalitre size with selections for contaminated or clean, lined or unlined, and the three land types. The key utility of this sheet is that it allows a listing of all dams and ponds either individually or by group so the user and the department can clearly see the disturbance footprint assigned to each. Further, as the calculation is by area, it improves alignment with other spatial data.

The user selects whether the dam or pond is contaminated or clean, the size or capacity in megalitres, whether the dam or pond is in pasture, native, or arid land, whether it is lined or unlined, and whether it is regulated or non-regulated. The selections except for regulated/non-regulated, determine the per area rate applied to the row. The user then enters the number of dams and ponds in that category or row. The entry to this column must be a whole number, that is no decimals, and the calculator will communicate an error if a whole number is not entered. The user then enters the disturbance area for the dams and ponds in that row. For clarity, if more than one dam or pond is entered to a row, the user must enter the sum of the disturbance areas for each dam or pond. The area is the crest area of the structure. The per area rate is multiplied by the total disturbance area to get the total cost for each dam or pond in the category.

The number of dams and ponds in the category is for information only and does not feature in the calculation. It is not mandatory to enter the number but will assist the department to understand what is being costed. The regulated/non-regulated selection also does not feature in the calculation. Whether a dam is regulated or non-regulated is dependent upon the consequence category for the structure. Further information can be found in department's guidance document Structures which are dams or levees constructed as part of environmentally relevant activities (ESR/2016/1934). This regulated or non-regulated selection provides information needed by the department to reconcile spatial data, assist in assessment and compliance, and improve overall data and reporting of authorised water storages. The selection should be consistent with any regulated dam register required to be kept as part of the environmental authority.

The selection of contaminated or clean contents is a decision for the user. Generally, dams and ponds such as interceptors receiving oily water should be considered contaminated. The difference between contaminated and clean is the assumed sediment thickness which can be seen in the Assumptions sheet. A lined dam is assumed to have a plastic liner like high density polyethylene. Clay lined dams without a plastic liner are considered unlined.

For large dams where the land type may change, the user may need to split the disturbance between two land categories. The number of dam or ponds in each category, for example 0 to <= 50 megalitres contaminated, lined, pasture, are summed on the right hand side of the sheet and multiplied by the associated rate to get a total cost for the category. The cost for all categories is summed and displayed at the top of the sheet and reported to the Water Storage input sheet row in the Main sheet. The Water Storage input sheet rates do not include an allowance for water management, and this must be entered into the Main sheet if applicable. Entry to this sheet starts as usual with the map ID and then the name of the dam or pond or group of dams or ponds. The user then works across the drop-down menu columns selecting the item that best represents the item being costed. Remember, the number of dams and ponds in the category or row does not feature in the calculation but provides context for the reviewer. Further, if more than one dam or pond is entered to a row, the user must enter the sum of the disturbance areas for each dam or pond. We will work through an example with one row of a group of dams or ponds and three individual line items.

After entering the map ID we enter the name. For this first row, we are assuming there are five small ponds in an area. For a group entry to be made, the pond characteristics must be similar and fit within the drop-down categories. Our five ponds are ponds associated with drilling supply water and clean, so we select clean from the first drop-down menu. The next selection is the capacity. The capacities can be different as long as they all fall within the capacity range selected for that row. Our five ponds have crest capacities of 1, 1.5, 2, 3.5, and 4 megalitres so they all fit within the zero to fifty megalitre section. The land in which they are situated is pasture so we select pasture in the land type column, and the ponds are lined to conserve water so we select lined in the lined column. The ponds are also non-regulated. We enter five into the number column. Three of the ponds have a crest area of 10 by 10 metres and the other two are 20 by 20 metres. We can enter the calculation for the total disturbance area to the cell to make it easier for us and to show the reviewer how the number was arrived at. So in this case, we enter brackets as we will divide by ten thousand to convert to hectares, three by ten by ten plus two by twenty by twenty, close brackets and then divide by ten thousand to get hectares. That’s it for this row and you can see the total disturbance area for the group of ponds is allocated to the zero to less than or equal to fifty megalitres, clean, lined, pasture column.

The next three entries will be individual dams. They are called Ochre 1, 2, and 3. We can enter all the names first. Ochre 1 is a lined evaporation pond containing clean water with a capacity of two thousand megalitres and crest area of thirty hectares in an arid environment. It is non-regulated. Ochre 2 is a lined process water pond receiving oily water of ten megalitres capacity and crest area of thirty by thirty metres (or 0.09 hectares) in an arid environment. It is regulated. Ochre 3 is a lined brine pond of two hundred megalitre capacity and a crest area of seven hectares in an arid environment. It is also regulated. On the right you can see how the calculator has allocated the quantities and at the bottom how the areas are multiplied by the per hectare rates. The total is shown at the top and reported to the Main sheet.

The Water Storage User Build sheet allows the user to construct a rate by defining specific items to the dams or ponds. The sheet has similar selections to the Water Storage user input sheet but allows the user more flexibility on specific items such as sediment thickness and liner area. The sheet uses the same underlying default rates as the Main sheet and the Water Storage user input sheet.

The sheet requires the user to input or select the dam or pond type, for example interceptor, oily/water, raw/produced water, brine, evaporation etc. The user also selects whether the structure is regulated or non-regulated, the number of structures in each category, the land type, the crest area, whether the structure is lined or unlined, the width, height and slope of walls, and the number of dams to share upfront cost.

The user must enter these elements for the calculation to work correctly and for the department to have sufficient information for review. The key elements required for the calculation to work are indicated by 'Key Input' in the row beneath the header, and the department will query the user if any of these are absent.

The user has the option to override defaults and calculated values for the following:

Liner area. If the user does not enter a liner area the calculation assumes a multiplier as shown within the formula cell. The calculation checks the liner section and sets the liner area to zero if unlined is selected. If the user enters a liner area less than the crest area, the cell in the 'Liner Warning' column turns red and displays an 'E'. If this was not an error, the user must provide justification.

User entered area of the wall. The area is calculated based on the dimension values already entered, however the user can over-ride this in this cell. The volume of dirt in bunds column will then use this value instead of the calculated value.

Bund wall perimeter. If the user does not enter a perimeter, the calculation simply calculates the average length of a wall and multiplies it by four.

Sediment thickness. If the user does not enter a sediment thickness, the calculation uses the default as shown in the Assumption sheet and linked to by a hyperlink in that column.

Growth media area. If the user does not enter a growth media area, the calculation assumes the entire crest area will receive growth media and be revegetated. If the user selects arid in the land type selection, the growth media area is automatically set to zero.

Growth media thickness. If the user does not enter a growth media thickness, the calculation uses the default as shown in the Assumption sheet and linked by a hyperlink in that column.

Area to investigate. If the user does not enter an area to investigate area, the calculation assumes the entire crest area will be investigated. In some cases, the user may determine that investigation is not required, in which case, justification must be provided.

The user can select the haulage distance and fleet size for sediment removal, dozer push in walls, and growth media. Further information on fleet selection is included in the user guide. The rate associated with each selection is sourced from the Subrates sheet which can be accessed by the hyperlinks.

The capacity or volume of the dam or pond in megalitres serves to indicate the cost in dollars per megalitre on the right-hand side of the table and is not mandatory to enter.

The calculator calculates the sum for each sub-activity, for example application of growth media associated with the structure, and adds these together to reach a total cost. The total for the structure is multiplied by the total number of structures in that category to obtain the total for the row. It is important that the entries made in each row are by a dam or pond, which is different to the Water Storage sheet where the total area for all the structures in that row are entered.

The 'number of dams to share upfront cost' column associated with land investigation acknowledges that one-off type costs associated with the investigation, for example preparation of health and safety and work plans, is typically shared among items that can be reasonably assumed to be visited in one investigation campaign. Omitting this entry is a common cause of error in this calculation.

An example of its use is where a single dam or pond is entered to a row and it is the only dam or pond in that area that will be investigated. In this case the entry will be one, indicating that the full one-off costs are applied to that dam or pond.

Another example is five dams of similar characteristics and in the same local area are added to a row. In this case it is reasonable to enter five indicating that the one-off costs will be split between all the dams.

Another example is where four dams of similar characteristics are entered to the row but are separated by hundreds of kilometres. In this case it may be reasonable to enter 2 indicating that two separate investigation campaigns will be undertaken.

Let's go through an example. As always, the map ID and name are entered first. Our example is one dam called Ochre 4. It is an evaporation pond with a crest capacity of one thousand megalitres and is a regulated structure. We enter one in the number of structures column and select native as this dam is in an area of native grasses. The crest area is 30 hectares and it is lined with a total liner area as per the drawings of 34 hectares. You can see the calculator assumes a liner area equal to the crest area multiplied by 1.2 to account for slopes unless the user overrides this. As an example if we entered 29 hectares for the liner area we see an error is communicated. Let's change it back to 34 and continue on. The next section is for pushing in the dam or pond walls which is basically an earthmoving activity. From the drawings we know the wall height is four metres, the wall width at the top is two metres, and the slope of the wall is one in three. You can see the cross-sectional area calculated based on these inputs. We accept this calculation rather than enter a specific cross-sectional area as it looks correct based on our other inputs. The calculator outputs a linear length of bund walls but we know from the drawings the actual length is 2,005 metres so we enter this to the user entered linear length of bunds cell to override the calculator. The calculator calculates the volume of soil in the bunds and this value will be used with the rates determined by selections made later in the row.

The next section is about the sediment of the dam. For this example, we are assuming we don't know the sediment depth so we accept the default thickness and subsequent calculation of sediment volume. As for the bund soil volume, this value will be used with the rates determined by selections made later in the row.

The next section is the application of growth media, and the calculated area and default thickness of 150 mm are appropriate for this dam. Consequently we accept the calculated volume for growth media which again will be used with the rates determined by selections made later in the row.

The next section is for land investigations. In this case we determined that an investigation is required so we accept the default area to investigate produced by the calculator.

The next columns are for fleet size and distance selections for each of the rehabilitation activities. There is further information on these items in the user guide and if the user is unsure they can leave the default selections. In general larger dams are likely to use larger fleets and have longer distances to transport quantities such as sediment. In this example we will be transporting sediment on average 2 kilometres and will be using a medium fleet. The walls will be pushed in with a maximum push length of 40 metres and using a large D10 dozer. The distance between source and average placement for growth media is 2 kilometres and we will be using the same fleet as for the sediment. In the unit rates section you can see the rates determined by the selections made by the user, and then the next section shows the results for multiplication of these by the corresponding quantities.

The final section shows the total cost for the dam and the total cost for all the dams in the row, and cost rates dollar per megalitre and per unit area. The cost rates are for context only and show an error message if the user has neglected to enter the required information, though the volume entry is not mandatory. The land investigation column indicates if the user has not entered the number of dams to share upfront cost item. The totals for each row are summed, reported to the top of the sheet, and then reported to the water storage user defined row in the Main sheet.

As always, for more information or specific instructions, please consult the user guide which is also available on the Business Queensland website, below the download for the calculator. See you in the next module.

Watch the video: Module 12 – Water storage.