Underground Stormwater Treatment Bunker is listed at 8 Lawrence Crescent in Manurewa, Auckland. It is a stormwater treatment facility rather than a park, and the directory gives no other description of it.
The linked website is for a stormwater equipment maker, which is a different business and is not used. The directory holds no details of what the site offers to visitors, its access, parking or opening hours, and no visitor comments beyond the rating. It gives no figures for other places nearby either, so we can say no more about it than its street and suburb.