A lot of the rapidly growing waste has been dumped at the Levin landfill near Hōkio Beach.
There have now been six fatal crashes on the North Island this weekend.
Police confirmed they are responding to the incident.
Kāpiti Coast Airport was still closed on Monday morning, after an online threat shut it down Sunday.
An update on when it will reopen is expected on Monday.
"Investigators believe all of these incidents are linked."
Police believe the assaults are related.
"If they do decide to close the airport they will have a huge fight on their hands."
"It takes that 'love local' message everyone's getting a step further."