This is the 12932nd most frequent Russian word.
ливневый
"Ливневый" means "related to heavy rain or downpours."
In this sentence, 'ливневый' describes the type of rain, implying it's intense and sudden.
Сегодня утром прошел сильный ливневый дождь.
This morning there was a heavy rainstorm.
Here, 'ливневый' refers to the drainage system dealing with stormwater or rainwater flows.
Просистема ливневых стоков требует ремонта.
The rainwater drainage system needs repair.
In this instance, 'ливневый' modifies 'коллектор' to denote equipment related to managing rainwater.