Við skilum spilliefni inn í hvert sinn sem við heimsækjum gámasvæðið.

Skila inn is a verb + particle combination meaning hand in, turn in, or submit. In the dictionary, you learn it as skila inn, but in a finite sentence the particle is often separated from the verb, so Við skilum spilliefni inn is completely normal.

So here inn belongs with skilum, not with í hvert sinn. The sequence inn í is just accidental here; it does not mean into in this sentence.

Because the subject is við, meaning we. The form skilum is the 1st person plural present of skila.

So:

• ég skila = I hand in
• við skilum = we hand in

The same thing happens later with heimsækjum: við heimsækjum = we visit.

The verb skila normally takes the thing being returned or handed in in the dative: að skila einhverju.

In this sentence, spilliefni is that thing. The reason the form does not visibly change is that spilliefni is a neuter -i noun whose singular form is the same in several cases, including the dative. So the case is there grammatically, even though the word looks unchanged.

In usage like this, spilliefni is often best understood as a collective or mass noun, similar to English hazardous waste. The sentence is talking about that category of material, not about counting separate items one by one.

So even if English learners expect a plural idea, Icelandic often uses spilliefni as a general label for the material.

Í hvert sinn sem means every time that, each time that, or simply whenever.

The noun sinn here means time or occasion. Hvert is the form of hver that matches sinn in this expression. You can think of the whole phrase as a fixed time expression meaning on each occasion that.

Sem introduces the subordinate clause við heimsækjum gámasvæðið. It links that clause to the time expression before it.

So:

• í hvert sinn sem við heimsækjum gámasvæðið
• = every time that we visit the recycling area

In English, this that/when is often omitted, but Icelandic keeps sem.

The sentence has two clauses, and each clause has its own subject:

• Við skilum spilliefni inn = We hand in hazardous waste
• sem við heimsækjum gámasvæðið = when we visit the recycling area

The second við is the pronoun we because it is followed by the finite verb heimsækjum. If við were the preposition meaning with/by/at, it would be followed by a noun phrase, not by a finite verb like that.

Because heimsækja means to visit and is a transitive verb. It takes a direct object, just like English visit does.

So Icelandic says:

• heimsækja gámasvæðið = visit the recycling area

You do not need á, til, or another preposition here.

Gámasvæðið is a compound noun built from gámur (container) and svæði (area, site). It refers to a container area, often something like a recycling or waste drop-off site.

The ending -ið is the suffixed definite article, so:

• gámasvæði = a container area
• gámasvæðið = the container area

In Icelandic, main clauses usually follow the verb-second pattern, but subordinate clauses introduced by words like sem usually do not. That is why the subordinate clause has the neutral order við heimsækjum rather than moving the verb forward.

Compare:

• Við skilum spilliefni inn.
  Main clause

• ... sem við heimsækjum gámasvæðið.
  Subordinate clause

Yes. Alltaf þegar við heimsækjum gámasvæðið can also mean whenever we visit the recycling area.

The difference is mostly one of style and nuance:

• í hvert sinn sem = a bit more explicit, sometimes slightly more formal or emphatic
• alltaf þegar = very natural too, often a bit more conversational

Both are good Icelandic.