Leak at base of external svp

Is the soil pipe U.P.V.C or old cast? if cast then its likely you are experiencing a common problem were the mortar around the base were it connects to the earthenware has crumbled it is repairable by placing a new band seal around the cast and earthenware pipe depending on the severity of the damage. A drain camera would identify what is required

If the there is a leak on this then just concreting will not help as it sounds like the svp has cracked and will need replacing to gain the correct seal.