08/1491 - MCU - Detached House [As Published] · 132008.1491

48 Runoff Controt

It is recommended a runoff diversion drain be constructed to divert runoff water away from untreated
excavated soil and excavation areas should these lie within a runoff pathway. The drain should be checked
daily to ensure it is servicable.

49 Ponded Water

If stormwater becomes ponded in bunded or disturbed areas affected by the presence of acid sulfate soil
then the pH should be checked prior to any off-site discharge. The pH should lie in the range of 5.5-8.5.
lf the pH is less than 5.5 then then pH can be raised by adding builders lime (staked lime or calcium
hydroxide). The builders fime is more soluble than agricultural lime but agricultural lime can be used if
necessary. The lime should be added in doses, mixed and the pH measured. The pH is likely to resist
change until it rises towards a value of 5.5. After this it will often rise quickly with small additions of lime.
The mixed water will be turbid but should settle overnight. it is preferable to allow the sediment to settle
prior to any discharge. If discharge of turbid water is necessary then sediment can be removed by filtration
through sand filter tanks or by stow overland flow across grassed areas.

Water quality should conform to the following criteria prior to discharge:

pH §.5-8.5

dissolved oxygen >=80% saturation
turbidity <100 NTU
suspended solids <25 mg/L
dissolved aluminium <0.1 mg/L
dissolved iron <1 mg/L

4.10 Groundwater

No groundwater analytical information is available.

441i Management of Groundwater

Geotechnical studies of the site have revealed the presence of groundwater and strata likely to provide a
significant groundwater flow. In the event of groundwater being encountered the management plan will
follow the actions described for "Ponded Water" in section 4.9. All water is to be pH tested prior to any
discharge.

 

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