MARBLEHEAD – The Smart Growth Committee showed 40 local residents some architects’ concept drawings for two Chapter 40R mixed-use developments that will add to the town’s stock of affordable housing.Peter Pitman, working for George Wattendorf, the owner of the former YMCA on Pleasant Street, described his vision for a four-story building with indoor parking on the first floor and 17 units of housing upstairs, 11 two-bedroom units and six one-bedroom units. The design offered 29 parking spaces indoors and outside. The “Y” will be torn down and replaced. The lot measures one-third of an acre.The original concept included underground parking, commercial units on the first floor and 20 units upstairs. The underground parking was eliminated due to neighborhood concerns about drainage and the commercial use was dropped after real estate people told the owner of the property there were already too many vacant small business spaces downtown.Architects Hubert Murray and Joseph Sirkovich presented their ideas for the former General Glover Restaurant property in Vinnin Square, which is partly in Swampscott, partly in Marblehead and partly in Salem. The Marblehead portion of the site is 1.56 acres. The site contains four acres.Murray, who has been working with the committee, offered three mixed-use options in five buildings, two in Marblehead and three in Swampscott. Each had several retail units on the Marblehead side. The first had 80 one-, two- and three-bedroom units and 160 parking spaces. The second had 80 two-bedroom units and 160 parking spaces. The third had 88 units and 172 parking spaces.Sirkovich’s designs, drawn several years ago for the Athanas family which owns the Glover property, featured underground parking and four residential buildings with 120 units, clustered around a a circular park area.In each case 20 percent of the units will be affordable, with preference given to town employees.Residents expressed concerns about both proposals, especially plans for the “Y” site,A committee handout indicated that a 40B development, which bypasses local zoning bylaws, could create as many as 23-53 housing units at the “Y” and as many as 109-249 units at the Glover site.Committee members pointed out that Smart Growth is a way of increasing the town’s amount of affordable housing without allowing developers to circumvent town bylaws. Chapter 40R offers communities a bonus of $3,000 per unit when building permits are issued, a priority on state capital funding for any needed improvements and a payment for school costs for any school-age children living in the new units.