Program Dell PowerConnect 6248P to handle another DHCP subnet from DHCP server

A client we just took on has a stack of 4 Dell switches the DHCP server is running out of DHCP leases the scope is 10.0.0.0/24 i created a superscope on the DHCP server adding 10.0.8.0/21, the DHCP server will hand out leases in my new scope but the devices with a lease on that range will not have internet connection. They can communicate between the two subnets though. Im thinking i have to create a VLAN on the dell switch in order to allow it to service these DHCP requests? the switch is on 10.0.0.254 and is the gateway for the orginial subnet, i know i need to create a virtual gateway on the 10.0.8.0 subnet. I can paste configs but this whole system was long configured before we took this client on.