If you want to read your whole file into an array anyway, you can use <FILE> in list context to get the whole file in one go. Use map to translate each line into the desired array reference.

my @sandGrid = map { chomp; [ split '', $_ ] } <FILE>;
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In the end it does the same thing as a loop but in a more compact way. Whether this suits your style you need to decide yourself.

Either way, it is always useful to use Data::Dumper to inspect what you've got:

use Data::Dumper;

...

print Dumper \@sandGrid;
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