Site Audit

Larger sites such as schools, strata managed facilities and government departments require a quote for approval before undertaking works over a certain value.

Lake Gwelup’s site audit included the following tests:

• Catch cups to measure sprinkler uniformity and distribution,
• Pressure and flow tested each zone
• Preliminary water titrations
• Inspection of irrigation and bore infrastructure

Findings

These are extracts from the report:

• No drawing available to show pipework and location of solenoid valves or sprinklers.
• No solenoids could be found in the oval.
• Some sprinklers are buried too deep and sprinkler water jet is not able to wet up as the turf obstructs the range.
• Low water pressure

ZONE 1

• Excellent uniformity with no dead sections of lawn
• 72% Distribution uniformity
• 76% Coverage uniformity

ZONE 2

• Sprinkler pressure weak – was in a deficit of 250 kPa
• 15 Sprinklers all under performing

ZONE 3

• Very low uniformity with several dead sections of lawn
• 58% Distribution uniformity
• 20% Coverage uniformity
• Sprinkler pressure in 280 kPa deficit

ZONE 4

• Green “doughnutting’ of grass from low distribution uniformity
• 18 Sprinklers with a pressure deficit of 240 kPa.
• Many sprinklers are buried too deep 

Solution

With the goal of raising sprinkler distribution and coverage to above 70% we completed the following works:

1. Locating soleneoid valves
   There were no irrigation drawings identifying each zone so we tested each zone and located each solenoid. Based on this we marked out a revised irrigation layout.
2. Added a new station
   We added a new station and split an existing zone into two resulting in increased water pressure to fewer sprinklers per zone. This is a standard procedure for commercial and residential projects and can be adjusted to work both ways  – in high and low pressure systems.
3. Raised or replaced sprinklers
   29 Sprinklers were raised because they were sitting too low and it was reducing sprinker distribution and coverage.

Outcome

It took about 100 cumulative man hours to identify and rectify Lake Gwelup Primary School’s low pressure problem. The irrigation system now has over 70% sprinkler distribution and coverage uniformity that will help the grounds thrive especially in summer. 

We confidently handed the upgraded irrigation system back to the school’s head groundsman.

With older systems typical of established schools we recommend moving to an organic fertiliser program. By applying liquid soluble fertilisers periodically the soil moves from a nutrient deficit state to a rich nutritious environment.

Traditional fertilisers are a short term fix for turf and gardens whereas organic fertilisers are additive in nature and stimuluate natural – long term soil improvement. 

Whilst we didn’t do this next step with Lake Gwelup Primary School, we highly recommend it for 90% of sites.