WESTPORT — If lifelong resident Martin Costa can help it, there will be tons of green COW t-shirts all over Westport on May 22. But these t-shirts won’t be used to celebrate the town’s agricultural heritage. They instead will stand for a growing movement — Clean Our Westport safety t-shirts for those who will be cleaning up litter. Costa, the retired owner of Westport Camping Grounds, has always had a love for the outdoors and spent decades cleaning up the 33-acre Westport Camping Grounds on Old County Road. “The snow has melted and in my excitement to get outdoors, I am disgusted by all the street-side litter that was hiding under the snow,” Costa said in a recent Facebook post. “It’s time for another Westport street clean up day.”