Ann: Quarterly Activities Report, page-12

it appears the two ponds were deliberately different:

Brine addition and monitoring of two pilot evaporation ponds continued during the quarter to assess evaporation and brine seepage rates for two different pond construction methods at the LD site.... ​

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Pond 2 (230 m2) was effectively a fully (membrane) lined pond for which seepage was expected to be negligible and was in fact so.....​

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Pond 1 (400 m2) was partially lined and significant seepage occurred from this pond. However the seepage rate from Pond 1 is decreasing with time and valuable design data has been derived from the trial.​

as for the clean-out, this brought a positive result:

The clean out of the two 1 km trenches during the period had important ramifications for the LD project in the context of potential Acid Sulfate Soil (ASS) generation within the LD Playa​

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The clean out of the two 1 km trenches during the period had important ramifications for the LD project in the context of potential Acid Sulfate Soil (ASS) generation within the LD Playa...​

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Comprehensive analysis of brines and sediments removed from the trenches after a period of inactivity and lake surface flooding showed no discernible generation of Monosulfidic Black Oozes (MBO’s) or evidence of acid generation (ASS) effects.​

Volatile sulfur and heavy metal ion levels were generally below laboratory detection levels. Brines extracted were near neutral in pH and had significant Acid Neutralizing Capacity (ANC). The outcome of the test program is regarded as very encouraging as ASS generation can be a significant environmental problem in inland lakes and waterways.​