How to Rerieve All Alerts on lists and libraries in a site collection

$SPSiteCollection = Get-SPSite "<List URl>"
$AlertsCollection=@()
foreach($SpWeb in $SPSiteCollection.AllWebs)
{
foreach($alert in $SpWeb.Alerts)
{
$oAlert = New-Object PSObject
Add-Member -InputObject $ouser -MemberType NoteProperty -Name UserName -Value ""
Add-Member -InputObject $ouser -MemberType NoteProperty -Name ListURL -Value ""
Add-Member -InputObject $ouser -MemberType NoteProperty -Name AlertTitle -Value ""
$oAlert.UserName  = $alert.user
$oAlert.ListUrl =  $alert.ListUrl
$oAlert.AlertTitle = $alert.title
$AlertsCollection +=$ouser
}
}
$AlertsCollection |  select UserName,ListUrl,Alerttitle | OUT-GridView