with SampleData as ( -- this cte simply provides the sample data for the query
select
    strval
from
    (values ('0008.22816'),('069.3142'))dt(strval))
select
    strval,
    right('0000000' + substring(strval,1,charindex('.',strval) - 1), 7) +
    '.' +
    right('0000000' + substring(strval,charindex('.',strval) + 1,len(strval) - charindex('.',strval)), 7)
from
    SampleData;

DECLARE @Tab TABLE
( 
  Value DECIMAL (14,7)
)

INSERT INTO @Tab (Value)
          SELECT 0008.22816 -->> 0000008.0022816
UNION ALL SELECT 069.3142 -->> 0000069.0003142

SELECT T.Value
      ,OtrApp.ConvVal
      ,[7.7 Format]= RIGHT(('0000000'+CrsApp.Whole) , 7) + '.' + RIGHT (('0000000'+CrsApp.Frac) , 7)
FROM   @Tab T
OUTER APPLY ( SELECT CONVERT(VARCHAR(15),T.Value)) OtrApp (ConvVal)
CROSS APPLY (SELECT  LEFT (OtrApp.ConvVal , CHARINDEX('.',OtrApp.ConvVal)-1)
                    ,STUFF(OtrApp.ConvVal,1,CHARINDEX('.',OtrApp.ConvVal),'')
             ) CrsApp (Whole,Frac)

with t(v) as ( select '0008.22816' union all select '069.3142' )
select
	[formattted] =
		replace(str(parsename(t.v,2),7),' ','0') + '.' +
		replace(str(parsename(t.v,1),7),' ','0'),
	* 
from t

DECLARE
    @S VARCHAR(50)
   ,@Split CHAR(1)
   ,@X XML
   ,@strNewValue VARCHAR(50)
 

SET @S = 0008.22816 -->> 0000008.0022816
SET @S = 069.3142   -->> 0000069.0003142

SET @Split = '.'

--split the two parts into separate elements using the XML reader
SELECT @X = CONVERT(XML,'<root><s>' + REPLACE(@S,@Split,'</s><s>')+'</s></root>')

SELECT
    --recombine the elements
    @strNewValue = COALESCE(@strNewValue + @Split,'')
    + CAST(Result.PaddedValue AS VARCHAR(MAX))
FROM
	(
	SELECT
		--add the padding
		REPLICATE('0',7-LEN(CAST(Value AS INT)))+Value AS PaddedValue
	FROM
		(
		--make some table rows
		SELECT T.c.value('.','VARCHAR(MAX)') AS [Value] FROM @X.nodes('/root/s') T (c)
		) Element
	) Result

SELECT
    @strNewValue AS NewValue