Date: Fri, 30 Oct 2020 21:05:03 +1100 (AEDT) Message-ID: <1842787741.69633.1604052303031@VPS1162916> Subject: Exported From Confluence MIME-Version: 1.0 Content-Type: multipart/related; boundary="----=_Part_69632_1283434131.1604052303031" ------=_Part_69632_1283434131.1604052303031 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Content-Location: file:///C:/exported.html Ponds and Sedimentation Basins (Costing)

# Ponds and Sedimentation Basins (Costing)

The process for undertaking a life cycle costing analysis for po= nds and sediment basins is the same as described in Life-Cycle Costing - Constructed Wetlands and Life-Cycle Costing - Bio= retention Systems.

The origin of all of the =E2=80=98expected=E2=80=99 values and algorithm= s in MUSIC=E2=80=99s costing module, as well as the statistical operations = used to generate =E2=80=98upper=E2=80=99 and =E2=80=98lower=E2=80=99 estima= tes for ponds and sediment basins are explained in Table 1.

## Tip Box<= /h2> Worked Example -<= /p> To Manually Adjust the Estimate of V for Sediment Basins = and PondsOne of the alternative algorithms in Table 7-4. allows users to es= timate the typical annual maintenance cost using the size attribute V, where V is the volume of material removed from the basin / po= nd (in m3/year). Currently, MUSIC calculates V by addin= g the estimated volume of gross pollutants, coarse sediment and total suspe= nded solids (TSS) that are trapped in the basin / pond per year. A worked example is given below showing how to manually calculate = an estimate of V that includes TSS, coarse sediment and/or gross p= ollutants. For example, an estimate may be required of the volume of only t= rapped coarse sediment and TSS, as these materials could potentially be reu= sed. Consider an urban catchment in Melbourne 20 ha in size with 50% im= pervious area that generates stormwater that is to be treated by a 194 m2 sediment basin (sized to trap 80% of the TSS load). The load of trapped TSS is calculated by right-clicking on the bas= in=E2=80=99s treatment node icon and examining the Statistics =C2=BB M= ean Annual Loads section of MUSIC. In this example, the inflow load is 11,7= 00 (kg/year) and the outflow load is 2,340 kg/year, so the trapped load is = 9,360 kg/year. Using a mass to volume conversion factor of 1,800 kg/m3= for sediment, this equates to a volume of 5.20 m3/year. Using the same procedure for gross pollutants, the inflow load is = 2,550 kg/year and the outflow load is 0 kg/year (as MUSIC assumes 100% is c= aptured). Using a mass to volume conversion factor of 260 kg/m3 = for gross pollutants, this equates to a volume of 9.81 m3/year.<= /span> For coarse sediment, it is known that in gross pollutant traps tha= t capture nearly all coarse sediment and gross pollutants, approximately 29= % of the volume is sediment (on average). So the load of coarse sediment (m= 3/year) =3D the volume of trapped gross pollutants (i.e. 9.81 m3= /year) =E2=80=A2 0.4085 =3D 4.01 m3/year. Now the three elements of the total trapped volume are known, the = user can choose which of these should be added to estimate V.

Table 1 Summary of cos= t-related relationships for ponds and sediment basins.

Element of Life= Cycle Costing Model

Default Option = for Estimation in MUSIC

Alternative(s)<= /p>

Notes

Life cycle

50 years (From collected survey data, n =3D 3)

No alternative in music.

One could convincingly argue the life cycle i= s infinite for well-maintained ponds / basins, but we need to set the LC to= a finite number to calculate a life cycle cost.

Upper and lowe= r estimates derived using a 84th and 16th percentile, respectively.

Total acquisition cost (TAC)

TAC (\$2004) =3D 685.1=E2=80=A2(A)0.7893

R2 =3D 0.99; p < 0.01; n =3D 4

Where: A =3D surface ar= ea of treatment zone in m2

No alternative size / cost relationships in M= USIC.

For literature values, see Taylor (2005b) =E2=80=93 included in= Appendix H.

Upper and lower estimates derived using a 68%= (or 1 standard deviation) prediction interval for the regression.

No= te that a linear equation (TAC =3D 96.15=E2=80=A2(A) + 16,200)= produced a slightly higher R2 value, but due to th= e behaviour of the relationship when the treatment device size is small, th= e power relationship was preferred.

Typical annual maintenance (TAM) cost

&nbs= p;

TAM (\$2004) =3D 185.4=E2=80=A2(A)0.4780<= /sup>

R2 =3D 0.92; p =3D 0.04;&nbs= p;n =3D 4

Where: A =3D surface area of the basin/pond i= n m2

TAM (\$2004) =3D 698.3=E2=80=A2(A)0.7766<= /sup>

R2 =3D 0.72; p < 0.01;&nb= sp;n =3D 57

Where: V =3D average annual volume= of removed material in m3 (were =E2=80=9Cremoved m= aterial=E2=80=9D includes trapped gross pollutants, coarse sediment and TSS= ).

For literature values, see Taylor (2005b)

Upper and lower estimates derived using a 68%= (or 1 standard deviation) prediction interval for the regression.

Warning: The alternative cost / size relation= ship is based on an =E2=80=9Copen gross pollutant trap=E2=80=9D data set, a= s these treatment devices are essentially a pond / basin with a trash rack.= In addition, currently music estimates V using the=20 combined estimated volume of gross pollutants, coarse sediment= and TSS that are trapped in the basin / pond. To adjust this=20 manually (i.e. to include only one or two of these three eleme= nts), use the procedure provided in the tip box within this section.

Estimates from the North American and Australian literature (see T= aylor, 2005b) suggest that ponds typically cost ~3% - 6% of the constructio= n cost to maintain per year (equates to ~5.5% of the TAC, based on the CRCC= H data set for sediment basins and ponds). Note however that the CRCCH data= set for these types of device does not support the hypothesis that a stron= g correlation exists between TAM and TAC (albeit based on limited data).

Annualised renewal / adaptation= cost (RC)

RC (\$2004) =3D 1.4% of TAC p.a.=

n =3D 4

No alternative size / cost rela= tionships in MUSIC.

For literature values, see Taylor (2005b)

Upper and lower estimates deriv= ed using a 84th and 16th percentile, respectively.

Renewal period

1 year

(Default position = due to lack of high quality data supporting an alternative per= iod)

10 years

There is weak evidence= that major renewal / adaptation costs occur every 10 years on average (e.g= . costs associated with access ramps, re-contouring), but this is likely to= vary significantly on a site-by-site basis.

Decommissioning cost (DC) =

DC (\$2004) =3D 38% of TAC

n =3D 3

No alternative size / cost relatio= nships in MUSIC.

General caveats / notes for thi= s type of device

* There are several estimates o= f capital and maintenance costs reported in the literature for sediment pon= ds and basins (see Taylor, 2005b or Appendix H: Costing information for a summary).&nbs= p;