Liang - Vallco impact during heavy rain

From: Liang C

Date: Mon, Nov 16, 2015 at 8:59 AM
Subject: Comment on Vallco EIR - impact of heavy rain
To: "City of Cupertino Planning Dept." <planning@cupertino.org>

RE: Comment on Vallco EIR

Although it doesn't rain much in Silicon Valley, during rainy season, there might be heavy rain, which results in flooding in different areas of the City.

The Hills at Vallco will cover the entire 52-acre of the site with concrete. When it rains heavily, all of the rainwater from the 52-acre would accumulate and it may become a torrent.

Please study the rainwater collection system to see if the capacity is sufficient to cover the heavy rainfall. In case of even heavier rain, please study the impact of an overflow from rain water collection system.

Since the rooftop has varying height from 114 feet to 65 feet at street level, please study the impact of heavy rainwater overflow that might cause more slippery road condition on Wolfe Road and other impacted roads.

On the greenroof slope at west side, which goes from street level to 45 feet and then 65 feet in a short distance, please study the impact of heavy rainwater overflow onto the Perimeter Road.

Please study the safety of bike paths during heavy rain. Is any bike path in danger of being flooded with rainwater on its way to drainage system.

Please study the impact of traffic condition during heavy rain when most people won't bike or walk or even take bus to work, since most bus stops do not have anything to protect waiting passengers from rain.